Flash Joule Heating for the Production of 1D Carbon and / or Boron Nitride Nanomaterials

Abstract

Flash Joule heating (FJH) for the production of one-dimensional (1D) carbon and / or boron nitride nanomaterials, as well as 1D materials integrated with 0D, 1D, 2D, and 3D nanomaterials, composites, nanostructures, networks, and mixtures thereof. Materials produced by such FJH include 1D carbon and hybrid nanomaterials, boron nitride nanotubes (BNNTs), turbostratic boron-carbon-nitrogen (BCN), doped (substituted) graphene, and heteroatom-doped (substituted) reflashed graphene.

Description

Related Applications

[0001] Cross-reference to related patent applications This application claims priority to U.S. patent application Ser. No. 63 / 341,934, entitled "Flash Joule Heating For Production Of 1D Carbon And / Or Boron Nitride Nanomaterials, 1D Materials Integrated With 0D, 1D, 2D, And 3D Nanomaterials, Composites, Nanostructures, Networks, Or Mixtures Thereof," filed May 13, 2022, which is commonly owned with the owner of the present invention. This patent application is incorporated herein in its entirety. [Technical Field]

[0002]

[0002] The present invention relates to flash joule heating for the production of 1D materials integrated with 1D carbon and / or boron nitride nanomaterials, 0D, 1D, 2D, and 3D nanomaterials, composites, nanostructures, networks, doped or substituted materials, and mixtures thereof.

[0003] STATEMENT REGARDING FEDERALLY FUNDED RESEARCH This invention was made with government support under Grant No. FA9550-22-1-0526 awarded by the United States Air Force Office of Scientific Research, and Grant No. FE0031794 awarded by the National Science Foundation (Graduate Research Fellowship), and U.S. Army Corp. of Engineers, ERDC No. W912HZ-21-2-0050. The U.S. Government has certain rights in this invention.

[0004] STATEMENT REGARDING FEDERALLY FUNDED RESEARCH This invention was made with government support under Grant No. FA9550-22-1-0526 awarded by the Air Force Office of Scientific Research, Grant No. FE0031794 awarded by the National Science Foundation, and Grant No. W912HZ-21-2-0050 awarded by the U.S. Army Corps of Engineers. The government has certain rights in this invention. [Background technology]

[0005]

[0005] One-dimensional (1D) carbon materials One-dimensional (1D) carbon materials have received considerable research and attention since their discovery in the late 20th century [Ajayan 2001; Rathinavel 2021; Ruiz-Cornejo 2020; Yang 2015]. While carbon nanotubes provide the most widely recognized example of such 1D materials, many subclasses and different morphologies have been characterized [Shi 2019; Kou 2017]. Examples of these 1D carbon nanomaterials include both single-walled and multi-walled carbon nanotubes (CNTs), as well as ribbon- and plate-like carbon nanofibers, bamboo-like carbon nanotubes, cup-stacked carbon nanofibers, and many others [Feng 2014; Jai 2017; Liu 2021; Wang 2019]. 1D materials are widely used in composites, coatings, sensors, electrochemical energy storage, and electrocatalysis, taking advantage of their strength, conductivity, low density, broadband electromagnetic absorption, high surface area, and chemical robustness [Restivo 2020; Kumar 2021; Kour 2020; Wu 2021]. Due to their widespread utility and scientific interest, identifying new methods for synthesizing 1D carbon materials remains crucial. Most synthetic strategies for forming 1D carbon materials, such as arc discharge, laser ablation, chemical vapor deposition, plasma torch, and high partial pressure carbon monoxide, involve mobilization of carbon atoms in a feedstock on the surface of a catalytic metal, which then grows into a graphitic 1D form [Xu 2019]. These current methods often result in a mixture of 1D materials and amorphous carbon, which requires separation, and 1D material synthesis often suffers from low production rates below 1 g / h. [Lee S 2021;McLean 2021;Rao 2018].

[0006]

[0006] In recent years, research has focused on converting waste plastics into higher-value carbon nanomaterials, driven by the low cost and high availability of feedstock materials [Yaqoob 2022; Wang 2020; Williams 2021]. However, these methods often use a two-step chemical vapor deposition pyrolysis process: in the first step, the plastic is decomposed into volatile hydrocarbons at temperatures of 700–900°C for 0.5–2 hours under an inert atmosphere [Zhuo 2014; Sharma 2020]. In the second step, the hydrocarbon gas is then grown into 1D materials on complex transition metal catalysts at similarly high temperatures for several hours, again under an inert atmosphere [Wang 2022; Bazargan 2012; Gong 2013]. Growth catalysts typically require dedicated synthesis or templating methods, which are time-, energy-, and resource-intensive. [Jie 2020;Ahamed 2020;Jia 2022].

[0007]

[0007] Furthermore, many of these methods use a 1:1 ratio of waste plastic to growing metal complex, which means that it is expected to require the production of one ton of metal complex for every ton of processed waste plastic, which is expected to hinder widespread implementation and economic viability [Cai 2021]. To the applicant's knowledge, the production of complex carbon hybrid materials from waste plastic has not yet been demonstrated. Current methods for producing carbon nanomaterials from waste plastic are hindered by long reaction durations and high resource consumption, large amounts of metal complex additives, and minimal scalability of chemical vapor deposition techniques.

[0008]

[0008] Flash Joule Heating (FJH) synthesis In recent years, flash Joule heating (FJH) has been promoted as an efficient method for the solvent-free synthesis of various carbonaceous and inorganic nanomaterials [Luong 2020; Wyss I 2022; Yao 2016; Deng 2022; Guo 2022]. Specifically, FJH has provided a facile method for upcycling low-value waste materials into high-value nanomaterials [Algozeeb 2020; Wyss I 2021; Advincula 2021; Wyss II 2021]. In the case of FJH synthesis of graphene, electrical energy and resistance are rapidly enhanced to generate high temperatures, and the short duration of FJH (0.05–1 s) restricts rotational motion, resulting in the formation of turbostratic or rotationally misaligned graphene. Temperatures exceeding 3,100 K are reached within a few milliseconds, resulting in the formation of highly ordered sp-bonded amorphous carbon nanotubes. 2 Reassembly into hybridized sheets is possible. [Wyss I 2022]. Flash graphene sheets form via a "mobile carbon" mechanism, where the temperature generated by high-resistance junctions within the sample allows for annealing and the formation of crystallized nanoparticles. [Stanford 2020]. The capacitance density of the reaction can also be controlled; reaction conditions can be controlled; increasing the charge per unit mass shifts the nucleation process from a diffusion-controlled kinetic-limited reaction. [Algozeeb 2020; Beckham 2022].

[0009]

[0009] Boron nitride nanotubes (BNNTs) Boron nitride (BN) is a highly attractive III-V compound due to its excellent properties, such as high thermal conductivity [Terao 2010; Zeng 2017], stability [Zhu I 2005; Lee 2016], excellent mechanical strength [Chen 2017; Lahiri 2010], and insulating performance [Zh 2009]. The two most studied BN allotropes are one-dimensional (1D) boron nitride nanotubes (BNNTs) and two-dimensional (2D) hexagonal BN (h-BN). BNNTs are considered structural analogs of carbon nanotubes (CNTs), in which carbon atoms are replaced by alternating boron and nitrogen atoms. This substitution enhances the nanotubes' oxidation resistance in air and leads to stronger interactions with polymers compared to carbon nanotubes [Huang 2011; Chen 2015].

[0010]

[0010] In 1994, Rubio et al. theoretically predicted the existence of BNNTs [Ruio 1994], which were later synthesized by Chopra et al. in 1995 using an arc discharge method [Chopra 1995]. Subsequently, BNNTs were synthesized using various methods, such as laser ablation [Yu 1998; Kim 2019; Bae 2022], ball milling combined with annealing [Chen 1999; Kim 2011; Zhuang 2016], template-assisted synthesis [Tay 2015; Wang 2008], chemical vapor deposition (CVD) [Pakdel 2012; Lourie 2000; Kim J 2018], and thermal plasma [Kim 2020; Fathalizadeh 2014].

[0011] The preparation method directly determines the length, diameter, and purity of BNNTs, which play an important role in their applications. CVD is widely regarded as the most promising method for producing high-quality BNNTs. This technology operates via the vapor-liquid-solid (VLS) growth mechanism [Zhi II 2005]. The yield and shape of BNNTs are highly dependent on device design, gas flow, precursors, and catalysts. However, CVD technology is still limited in its ability to produce BNNTs on a large scale. Methods using ball milling and annealing have been recognized for their ability to produce BNNTs in high yields at low cost. BNNTs prepared by this method primarily have a bamboo-like structure. Laser ablation and thermal plasma are suitable for preparing BNNTs at high production rates. Laser or high-temperature plasma is used as a heat source to provide high energy so that the surface temperature of the precursor quickly rises, gasifies, and produces thin-walled BNNTs. The reaction mechanism remains unclear, and a purification process is needed to remove these impurities, such as B and h-BN.

[0012]

[0012] Turbostratic boron-carbon-nitrogen (BCN) Regular layered materials typically have distinct thermodynamically favored stacking orders under standard temperature and pressure conditions [Luong 2020; Stanford 2020]. The stacking order is determined by various noncovalent interactions, such as van der Waals, London, and Kieson interactions [Smith 2011]. Deviations from these stacking morphologies result in the formation of turbostratic crystal lattices with inherently increased interlayer distances and weakened coupling interactions between adjacent layers [Advincula 2021; Algozeeb 2020], thereby introducing the unique optical, electrical, and magnetic properties of turbostratic materials and broadening their applications [Wyss I 2021; Chen II 2021].

[0013]

[0013] A major concern with the synthesis of turbostratic materials is the unfavorable formation energy and spontaneous relaxation to the thermodynamically favored stacking order: if a sustained heat source is provided, products with the thermodynamically most stable layered order will dominate, making the turbostratic structure difficult to access. [2,8~10] [Stanford 2020; Ba 2017; Song 2010; Xu D 2018] Therefore, most bottom-up methods for preparing layered materials cannot be employed for the synthesis of turbostratic materials due to insufficient relaxation energy barriers (<4 kJ / mol) [Rydberg 2003] and limited cooling rates (<10 K / sec) [Chilkoor 2020; Wang 2017]. The construction of regular in-plane configurations usually involves the formation of self-confined monolayers or well-ordered multilayer structures.

[0014] Previous studies have demonstrated that the formation of turbostratic structures can be induced by low-temperature (approximately 500 K) heat treatment or bias-assisted hot-filament chemical vapor deposition (CVD), but these products typically have a semicrystalline in-plane configuration with hybrid nanocrystalline and amorphous domains [Kakiagea 2013; Ahn 2000]. The semicrystalline in-plane structure can prevent the precise stacking of individual layers, thereby inducing the formation of turbostratic stacked structures. In addition, guest intercalation methods using ionic liquids [Lian 2009] and chemical functionalization [Cao 2022] have been used to stabilize turbostratic materials. These methods are believed to be due to the modification of interlayer interactions, such as hydrogen bonding and π-π stacking, between adjacent basal planes. Therefore, the direct synthesis of turbostratic materials with high in-plane crystallinity remains challenging when attempting to explore the unique properties caused by the weak coupling between adjacent layers.

[0015] For multicomponent systems, semicrystalline in-plane structures are common when starting from gaseous precursors, such as binary compounds of boron and nitrogen [Demirci 2020] and ternary compounds of boron, carbon, and nitrogen (BCN) [Ahn 2000; Puyoo 2017]. These reactive precursors, such as BCl3 and NH3 [Puyoo 2017] or ammonia borane (BH3NH3) [Zhong 2017], achieve rapid conversion, leading to the formation of amorphous products with numerous structural defects. Although the in-plane crystallinity of the products can be improved by controlling the annealing time and temperature, the thermodynamic limitations of these traditional bottom-up methods and the metastable nature of turbostratic materials with high in-plane crystallinity ultimately result in the formation of either semicrystalline structures or well-ordered stacked structures [Chilkoor 2020; Ahn 2000]. [Luong 2020;Stanford 2020].

[0016] Turbostratic disorder in 2D materials has mismatch between layers. The lack of alignment increases the inherent interlayer distance and weakens the optical and electronic interactions between adjacent layers. This introduces properties different from structures with well-ordered crystal lattices and strong coupling interactions. However, the straightforward and rapid synthesis of turbostratic materials remains challenging due to their thermodynamically metastable properties.

[0017]

[0017] Doped graphene Graphene is a 2D material with exceptional mechanical strength, electrical conductivity, and other desirable chemical properties. [Ye 2019]. To chemically modify graphene and tune its chemical, physical, and optical properties, it is often doped with non-carbon atoms (or the term "substituted" may be used if the replaced or added atoms can be greater than 5 wt%). [Wang 2014; Xu H 2018; Agnoli 2016]. These atoms may be arranged in the graphene crystal lattice, most commonly with atomic radii similar to those of carbon atoms, or may be added above and below the graphene crystal lattice, as in the case of the addition of fluorine atoms. The resulting crystal lattice often consists of heteroatoms up to a few percent in atomic ratio. In 2020, a prominent technique for mass-producing graphene, known as flash Joule heating (FJH), was unveiled, in which amorphous carbon compounds can be transformed into turbostratic graphene using electrical pulses. [Luong 2020]. Amorphous carbon can be obtained from various sources, such as coal products, waste plastics [Wyss II 2022; Wyss III 2022; Wyss I 2021], and rubber waste [Advincula 2021]. In 2022, a paper was published demonstrating the creation of heteroatom-doped flash graphene by mixing amorphous carbon feedstock with organic feedstocks containing non-carbon atoms, such as melamine or boric acid, and then flashing these feedstocks together [Chen 2022]. In this previously reported technique, the organic heteroatom feedstock is destroyed along with the amorphous carbon feedstock. During subsequent graphene formation, the non-carbon heteroatoms pre-existing in these feedstocks are themselves positioned within or on and under the graphene structure, resulting in doped graphene. The amount of non-carbon heteroatoms present in the graphene crystal lattice is described in terms of a doping percentage, which is the percentage of atoms in the graphene crystal lattice that are composed of non-carbon atoms.According to this method, in various tests using sulfur, nitrogen, boron, and fluorine atoms, doping percentages of up to 7.4% were achieved in the graphene crystal lattice with a single dopant flash, and slightly higher doping rates were achieved by using combinations of these dopants simultaneously. [Prior art documents] [Non-patent literature]

[0018] [Non-Patent Document 1] Ajayan, PM, et al., in Carbon Nanotub. Synth. Struct. Prop. Appl. (Eds.: MS Dresselhaus, G. Dresselhaus, P. Avouris), Springer, Berlin, Heidelberg, 2001, pp. 391-425 [Non-patent document 2] Rathinavel, S., et al., Mater. Sci. Eng. B, 2021, 268, 115095 [Non-patent document 3] Ruiz-Cornejo, JC, et al., Rev. Chem. Eng., 2020, 36, 493 [Non-patent document 4] Yang,W., et al., J. Am.Chem. Soc., 2015, 137, 1436 [Non-patent document 5] Shi, C., et al., Small,2019, 15, 1902348 [Non-patent document 6] Kou, L., et al., Nano-Micro Lett.,2017, 9, 51 [Non-Patent Document 7] Feng, L., et al., Materials, 2014, 7, 3919 [Non-patent document 8] Jia, Z., et al., Catalysts, 2017, 7,256

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[0019] The present invention relates to flash Joule heating (FJH) for the production of one-dimensional (1D) carbon and / or boron nitride nanomaterials, as well as 1D materials integrated with 0D, 1D, 2D, and 3D nanomaterials, composites, nanostructures, networks, and mixtures thereof. Materials produced by such FJH include 1D carbon and hybrid nanomaterials, boron nitride nanotubes (BNNTs), turbostratic boron-carbon-nitrogen (BCN), doped (substituted) graphene, and heteroatom-doped (substituted) reflashed graphene.

[0020] In general, in one embodiment, the invention features a method that includes flash joule heating a mixture of a material and a catalyst to form a one-dimensional structure. Implementations of the invention may include one or more of the following features.

[0021]

[0021] Flash Joule heating may be a process that involves applying a voltage across a mixture, whereby a current is passed through the mixture to form a one-dimensional structure. The voltage may be applied in one or more voltage pulses. The duration of each of the one or more voltage pulses may be over a period of time.

[0022]

[0022] The material may be a carbon material that is not substantially graphene.

[0023] The one-dimensional structures may be graphitic 1D and / or hybrid material nanomaterials.

[0023]

[0024] The method may further comprise forming a morphology of the one-dimensional structure together with one or more other dimensional structures selected from the group consisting of zero-dimensional structures, two-dimensional structures, and mixtures thereof.

[0024]

[0025] The one-dimensional structure and one or more other dimensional structures may be linked by covalent or non-covalent bonds.

[0026] The one-dimensional structure and one or more other dimensional structures may be connected to form a three-dimensional network.

[0025]

[0027] The material may be a carbon material containing a polymer.

[0028] The mixture may be formed by loading particles of catalyst onto the polymer via surface wetting.

[0026]

[0029] The mixture may be formed by loading particles of catalyst into the polymer via melt mixing.

[0030] The material may be a carbonaceous waste material.

[0027]

[0031] The catalyst may be selected from the group consisting of iron(II) chloride, nickel(II) chloride, cobalt(II) chloride, and ferrocene.

[0032] The catalyst may be selected from the group consisting of any transition or main group metal or transition or main group metal complex, salt, oxide, halide, or combination thereof.

[0028]

[0033] The mixture may further include a conductive carbon additive.

[0034] The conductive carbon additive can be selected from the group consisting of graphene, flash graphene, turbostratic graphene, anthracite, coconut shell-derived carbon, higher temperature processed biochar, activated carbon, calcined petroleum coke, metallurgical coke, coke, shungite, carbon nanotubes, asphaltenes, acetylene black, carbon black, ash, carbon fiber, and mixtures thereof.

[0029]

[0035] The conductive carbon additive may include carbon black and / or metallurgical coke.

[0036] The method may further include separating at least a portion of the conductive carbon additive from the formed one-dimensional structure after flash Joule heating.

[0030]

[0037] The separating step may be based on the particle size of the conductive carbon additive and the size of the formed one-dimensional structures.

[0038] The separating step may include sieving to separate the small one-dimensional structures from the larger particle size conductive carbon additive.

[0031]

[0039] After the separating step, the percent yield of the one-dimensional structures formed by the method may be at least 80%.

[0040] After the separating step, the yield percentage of the one-dimensional structure formed by this method may be 80% to 90%.

[0032]

[0041] The percent yield of one-dimensional structures formed by this method may be at least 65%.

[0042] The percent yield of one-dimensional structures formed by this method may be at least 80%.

[0043] In general, in another embodiment, the invention features a one-dimensional structure made by any of the methods described above.

[0033]

[0044] Implementations of the invention may include one or more of the following features:

[0045] The one-dimensional structure may be in the form of either a nanostructure or a microstructure, wherein the length of the one-dimensional structure is at least three times the width of the one-dimensional structure.

[0034]

[0046] The one-dimensional structure does not have to be a single atomic sheet thick.

[0047] In general, in another embodiment, the invention features a composite material that includes any of the one-dimensional structures described above.

[0035]

[0048] Implementations of the invention may include one or more of the following features:

[0049] The composite material may include a one-dimensional structure and a vinyl ester.

[0050] The composite material may be a one-dimensional structure reinforced vinyl ester resin nanocomposite.

[0036]

[0051] In general, in another embodiment, the invention features a structure or network made by any of the methods described above.

[0052] Implementations of the invention may include one or more of the following features:

[0053] The one-dimensional structure of the structure or network may be in the form of either a nanostructure or a microstructure, wherein the length of said one-dimensional structure is at least three times the width of said one-dimensional structure.

[0037]

[0054] The one-dimensional structure of the structure or network need not be a single atomic sheet thick.

[0055] In general, in another embodiment, the invention features a method that includes flash joule heating a mixture to form boron nitride nanotubes, the mixture including (i) a boron-containing material, (ii) a nitrogen-containing material, and (iii) a catalyst.

[0038]

[0056] Implementations of the invention may include one or more of the following features:

[0057] Flash Joule heating may be a process that includes applying a voltage across the mixture, whereby a current is passed through the mixture to form boron nitride nanotubes. The voltage may be applied in one or more voltage pulses. The duration of each of the one or more voltage pulses may be for a period of time.

[0039]

[0058] The boron-containing material and the nitrogen-containing material may be different materials.

[0059] The material containing boron and the material containing nitrogen are the same material.

[0060] The same material may be ammonia borane.

[0040]

[0061] The catalyst may be Ni(acac)2 and / or Fe(acac)3.

[0062] The catalyst may contain Ni and / or Fe.

[0041]

[0063] The mixture may further include a conductive carbon source.

[0064] The conductive carbon source can be selected from the group consisting of graphene, flash graphene, turbostratic graphene, anthracite, coconut shell-derived carbon, higher temperature processed biochar, activated carbon, calcined petroleum coke, metallurgical coke, coke, shungite, carbon nanotubes, asphaltenes, acetylene black, carbon black, ash, carbon fiber, and mixtures thereof.

[0042]

[0065] The conductive carbon source may include carbon black and / or metallurgical coke.

[0066] The mixture may contain (i) a material containing boron and a material containing nitrogen, and (b) a conductive carbon source in a weight ratio of 1:2 to 2:1.

[0043]

[0067] The method may further comprise separating at least a portion of the conductive carbon source from the formed boron nitride nanotubes after the flash Joule heating.

[0068] The separating step may be based on the particle size of the conductive carbon source and the size of the boron nitride nanotubes formed.

[0044]

[0069] The separating step may include sieving to separate the smaller boron nitride nanotubes from the larger particle size conductive carbon source.

[0070] After the separating step, the percent yield of boron nitride nanotubes formed by the method may be at least 45%.

[0045]

[0071] After the separating step, the percent yield of the one-dimensional structures formed by the method may be at least 60%.

[0072] The percent yield of boron nitride nanotubes formed by this method may be at least 45%.

[0046]

[0073] The percent yield of boron nitride nanotubes formed by this method may be at least 60%.

[0074] The products of this method may include boron nitride nanotubes and sheet-like structures.

[0047]

[0075] At least 30% of the product of the method may be boron nitride nanotubes.

[0076] In general, in another embodiment, the invention features a composition that includes boron nitride nanotubes made by any of the methods described above.

[0048]

[0077] In general, in another embodiment, the invention features a method that includes flash joule heating a mixture to form a turbostratic nanomaterial that includes (a) boron, (b) nitrogen, and (c) a third element selected from the group consisting of carbon, tungsten, or iron, where the mixture includes (i) a material that includes boron, (ii) a material that includes nitrogen, and (iii) a material that includes the third element.

[0049]

[0078] Implementations of the invention may include one or more of the following features:

[0079] Flash Joule heating may be a process that includes applying a voltage across the mixture, whereby a current is passed through the mixture to form a turbostratic nanomaterial. The voltage may be applied in one or more voltage pulses. The duration of each of the one or more voltage pulses may be for a period of time.

[0050]

[0080] The third element may be carbon and the turbostratic nanomaterial may be turbostratic BCN.

[0081] The third element may be tungsten and the turbostratic nanomaterial may be turbostratic BN-W.

[0051]

[0082] The third element may be iron and the turbostratic nanomaterial may be turbostratic BN-Fe.

[0083] The mixture may include (i) a material containing boron and a material containing nitrogen, and (b) a material containing a third element, in a weight ratio of greater than 4:1.

[0052]

[0084] The mixture contains (i) a material containing boron and a material containing nitrogen, and (b) a material containing a third element in a weight ratio of 1:2 to 2:1.

[0085] The percent yield of the turbostratic nanomaterial formed by the method may be at least 20%.

[0053]

[0086] The percent yield of the turbostratic nanomaterial formed by the method may be at least 30%.

[0087] In general, in another embodiment, the invention features a composition that includes a turbostratic nanomaterial that includes (a) boron, (b) nitrogen, and (c) a third element selected from the group consisting of carbon, tungsten, and iron, made by any of the methods described above.

[0054]

[0088] In general, in another embodiment, the invention features a method of forming doped or substituted graphene. The method includes performing a first flash Joule heating process using a first mixture to form a first formed graphene. The first mixture includes (i) a substantially non-graphene carbon source and (ii) a catalyst. The method further includes mixing one or more heteroatom doping compounds with the first formed graphene to form a second mixture. The method further includes performing a second flash Joule heating process using the second mixture to form the doped or substituted graphene.

[0055]

[0089] Implementations of the invention may include one or more of the following features:

[0090] The first flash joule heating process may include applying a first voltage across the first mixture, whereby a first current is passed through the first mixture to form first formed graphene. The first voltage may be applied in one or more first voltage pulses. The duration of each of the one or more first voltage pulses may be for a period of a first duration. The second flash joule heating process may include applying a second voltage across the second mixture, whereby a second current is passed through the second mixture to form doped or substituted graphene. The second voltage may be applied in one or more second voltage pulses. The duration of each of the one or more second voltage pulses may be for a period of a second duration.

[0056]

[0091] The first formed graphene may be a one-dimensional structure.

[0092] The one-dimensional structures may be formed by any of the methods described above.

[0093] The first formed graphene may be perforated or wrinkled graphene.

[0057]

[0094] The first formed graphene may be turbostratic graphene.

[0095] The carbon material may include a polymer.

[0096] The carbon material may be a carbon-containing waste material.

[0058]

[0097] The carbon material may be a plastic.

[0098] The carbon material can be selected from the group consisting of graphene, flash graphene, turbostratic graphene, anthracite, coconut shell-derived carbon, higher temperature processed biochar, activated carbon, calcined petroleum coke, metallurgical coke, coke, shungite, carbon nanotubes, asphaltenes, acetylene black, carbon black, ash, carbon fiber, and mixtures thereof.

[0059]

[0099] The conductive carbon material may include metallurgical coke and / or bituminous activated carbon.

[0100] The catalyst may be selected from the group consisting of iron(II) chloride, nickel(II) chloride, cobalt(II) chloride, and ferrocene.

[0060]

[0101] The catalyst may be selected from the group consisting of any transition or main group metal or transition or main group metal complex, salt, oxide, halide, or combination thereof.

[0061]

[0102] The method may further include separating at least a portion of the carbon material from the first formed graphene after the first flash Joule heating process.

[0062]

[0103] The separating step may be based on the particle size of the carbon material and the size of the first formed graphenes.

[0104] The separating step may include sieving to separate the smaller first formed graphenes from the larger particle size carbon material.

[0063]

[0105] The step of mixing to form a second mixture may comprise mixing exactly one heteroatom doping compound with said first formed graphene.

[0106] The step of mixing to form a second mixture may include mixing two or more heteroatom doping compounds with the first formed graphene.

[0064]

[0107] The one or more heteroatom doping compounds may each contain at least one heteroatom selected from the group consisting of boron, nitrogen, sulfur, and fluorine.

[0065]

[0108] The one or more heteroatom doping compounds may each be selected from the group consisting of boric acid, melamine resin, polyphenylene sulfide, and perfluorooctanoic acid.

[0066]

[0109] The one or more heteroatom doping compounds may include an organic powder having a low melting point.

[0110] The ratio of (i) one or more heteroatom doping compounds to (ii) the first formed graphene may be 1:8 to 1:2 by weight.

[0067]

[0111] The second flash joule heating process may be carried out under an argon atmosphere.

[0112] The carbon source may have a large particle size.

[0068]

[0113] The second flash joule heating process can be performed using a first second flash joule heating voltage and a second flash joule heating voltage, and the second second flash joule heating voltage can be greater than the first second flash joule heating voltage.

[0069]

[0114] The second second flash joule heating voltage may be at least twice the first second flash joule heating voltage.

[0115] The second second flash joule heating voltage may be at least five times the first second flash joule heating voltage.

[0070]

[0116] The second flash joule heating process can be performed using pulse width modulated DC electrical pulses from the discharge of a capacitor bank.

[0117] The second flash joule heating process can be carried out using modulated or unmodulated AC and DC current sources.

[0071]

[0118] The first flash joule heating process can be carried out in a first cylindrical reactor having a first diameter. The second flash joule heating process can be carried out in a second cylindrical reactor having a second diameter. The first diameter can be larger than the second reactor.

[0072]

[0119] Doped or substituted graphene may include heteroatoms doped into the graphene crystal lattice.

[0120] Doped or substituted graphene may include heteroatoms above or below the graphene crystal lattice.

[0073]

[0121] Doped or substituted graphene may contain heteroatoms doped into the graphene crystal lattice, or may contain heteroatoms above or below the graphene crystal lattice.

[0074]

[0122] The doping ratio of the doped or substituted graphene may be at least 10%.

[0123] The doping ratio of the doped or substituted graphene may be at least 20%.

[0075]

[0124] In general, in another embodiment, the invention features doped or substituted graphene made by any of the methods described above.

[0125] In general, in another embodiment, the invention features a method that includes incorporating any of the doped or substituted graphenes described above into concrete to increase the mechanical strength of the concrete.

[0076]

[0126] In general, in another embodiment, the invention features concrete that includes any of the doped or substituted graphenes described above.

[0127] In general, in another embodiment, the invention features a method that includes incorporating any of the doped or substituted graphenes described above into an epoxy to increase the mechanical strength of concrete.

[0077]

[0128] In general, in another embodiment, the invention features an epoxy that includes any of the doped or substituted graphenes described above.

[0129] In general, in another embodiment, the invention features a battery having a battery electrode that includes any of the doped or substituted graphenes described above. [Brief explanation of the drawings]

[0078] [Figure 1-1]

[0130] Figures 1A–1F illustrate the preparation of flash 1D materials (F1DMs). Figure 1A is a schematic of the FJH process for forming F1DMs and representative scanning electron microscope (SEM) images showing carbon-rich F1DM-rich regions of the sample. Figures 1B–1C are SEM images of F1DM-rich regions within the sample, demonstrating the entangled arrangement of the produced 1D materials. TEM images of various F1DM morphologies, including ribbon-shaped nanofibers (Figure 1D), bamboo-like nanofibers (Figure 1E), and multi-walled nanotubes (Figure 1F). Lattice fringes are highlighted with yellow lines to guide the eye, and the average layer spacing for each morphology is also provided. The fast Fourier transform of Figure 1F is shown in the inset, demonstrating the prominent (002) interference fringes of the nanotubes. Scale bars in the images correspond to (i) 5 μm in Figure 1A, (ii) 3 μm in Figure 1B, (iii) 300 nm in Figure 1C, and (iv) 10 nm in Figures 1D–1F. [Figure 1-2]Figures 1A-1F illustrate the preparation of flash 1D materials (F1DMs). Figure 1A is a schematic of the FJH process for forming F1DMs and a representative scanning electron microscope (SEM) image showing the carbon-F1DM-rich region of the sample. Figures 1B-1C are SEM images of the F1DM-rich region within the sample, demonstrating the entangled arrangement of the produced 1D material. TEM images of various F1DM morphologies, including ribbon-shaped nanofibers (Figure 1D), bamboo-like nanofibers (Figure 1E), and multi-walled nanotubes (Figure 1F). Lattice fringes are highlighted with yellow lines to guide the eye, and the average layer spacing for each morphology is also provided. The fast Fourier transform of Figure 1F is shown in the inset, demonstrating the prominent (002) interference fringes of the nanotubes. Scale bars in the images correspond to (i) 5 μm in Figure 1A, (ii) 3 μm in Figure 1B, (iii) 300 nm in Figure 1C, and (iv) 10 nm in Figures 1D–1F. [Figure 1-3] Figures 1A-1F illustrate the preparation of flash 1D materials (F1DMs). Figure 1A is a schematic of the FJH process for forming F1DMs and a representative scanning electron microscope (SEM) image showing the carbon-F1DM-rich region of the sample. Figures 1B-1C are SEM images of the F1DM-rich region within the sample, demonstrating the entangled arrangement of the produced 1D material. TEM images of various F1DM morphologies, including ribbon-shaped nanofibers (Figure 1D), bamboo-like nanofibers (Figure 1E), and multi-walled nanotubes (Figure 1F). Lattice fringes are highlighted with yellow lines to guide the eye, and the average layer spacing for each morphology is also provided. The fast Fourier transform of Figure 1F is shown in the inset, demonstrating the prominent (002) interference fringes of the nanotubes. Scale bars in the images correspond to (i) 5 μm in Figure 1A, (ii) 3 μm in Figure 1B, (iii) 300 nm in Figure 1C, and (iv) 10 nm in Figures 1D–1F. [Figure 1-4]Figures 1A-1F illustrate the preparation of flash 1D materials (F1DMs). Figure 1A is a schematic of the FJH process for forming F1DMs and a representative scanning electron microscope (SEM) image showing the carbon-F1DM-rich region of the sample. Figures 1B-1C are SEM images of the F1DM-rich region within the sample, demonstrating the entangled arrangement of the produced 1D material. TEM images of various F1DM morphologies, including ribbon-shaped nanofibers (Figure 1D), bamboo-like nanofibers (Figure 1E), and multi-walled nanotubes (Figure 1F). Lattice fringes are highlighted with yellow lines to guide the eye, and the average layer spacing for each morphology is also provided. The fast Fourier transform of Figure 1F is shown in the inset, demonstrating the prominent (002) interference fringes of the nanotubes. Scale bars in the images correspond to (i) 5 μm in Figure 1A, (ii) 3 μm in Figure 1B, (iii) 300 nm in Figure 1C, and (iv) 10 nm in Figures 1D–1F. [Figure 2-1]

[0131] Figures 2A-2F show the characterization of F1DM synthesized from virgin HDPE powder. Figure 2A shows a representative high-resolution magnified Raman spectrum of a sample of F1DM compared to a control sample in which no metals were incorporated but all FJH parameters were the same. [Figure 2-2] Figure 2B shows the Raman spectrum of the F1DM sample compared to the control sample, showing the average Raman spectrum from a 36 μm2 area and the absence of radial breathing mode peaks in the control sample. Figure 2C shows the Raman spectrum of the M, TS1, and TS2 peaks in the high-resolution F1DM sample compared to the control sample, showing the presence of the M peak only in the F1DM sample. [Figure 2-3] FIG. 2D is a powder XRD comparing F1DM with a control sample in which no starting material and no metal catalyst were used but all other parameters were identical. [Figure 2-4]Figure 2E is a powder XRD spectrum comparing the (002) peak of the F1DM and control samples, showing the multi-Lorentzian peaks of F1DM. Figure 2F is a powder XRD spectrum showing the (101) and (100) peak areas, showing the enhanced (101) peak in the F1DM sample. [Figure 3-1]

[0132] Figures 3A-3F show the characterization of F1DM synthesized from post-consumer mixed waste plastics. Figure 3A is a Raman spectrum showing F1DM derived from mixed waste plastics characterized by a large-area Raman average spectrum. Figure 3B is a powder XRD comparing the waste plastics to the synthesized F1DM. Figure 3C is a survey and high-resolution XPS. Figure 3D is an SEM image showing the morphology of F1DM derived from waste plastics. [Figure 3-2] Figure 3E and Figure 3F are SEM images showing the morphology of F1DM derived from waste plastic. [Figure 4-1]

[0133] Figures 4A-4I show electron microscope images showing regions of 1D and 2D morphologies colocalized to form a graphitic hybrid material and molecular dynamics models. Figures 4A-4D are SEM images showing the colocalization and coalescence of 1D and 2D graphitic materials, with the 2D morphologies attached to the edges of the 1D morphologies. Figure 4B is an SEM image showing the colocalization and coalescence of 1D and 2D graphitic materials, with the 2D morphologies attached to the edges of the 1D morphologies. Figure 4C is an SEM image showing the colocalization and coalescence of 1D and 2D graphitic materials, with the 2D morphologies attached to the edges of the 1D morphologies. [Figure 4-2] Figure 4D is an SEM image showing the colocalization and fusion of 1D and 2D graphitic materials, with 2D forms attached to the edges of the 1D forms. Figure 4E is a TEM image showing an area of ​​colocalization of bamboo-like carbon nanofibers and graphene sheet edges. Figure 4F is a high-resolution TEM image of the area highlighted in Figure 4F. [Figure 4-3]Figure 4G is a TEM image of bamboo-like nanofibers integrated with graphene flakes. Figure 4H is an atomic resolution TEM image of the highlighted area in Figure 4G. Figure 4I is a fast Fourier transform (FFT) showing AB stacking in the hybrid material shown in Figure 4H. Scale bars in the images correspond to (i) 20 μm in Figure 4A, (ii) 3 μm in Figures 4B-4C, (iii) 1 μm in Figure 4D, (iv) 20 nm in Figures 4E-4F, (v) 100 nm in Figure 4G, and (vi) 20 Å in Figure 4H. [Figure 5-1]

[0134] Figures 5A-5I show quantitative analysis of size and morphology control via FJH parameter tuning. Figures 5A-5D are confidence interval plots examining the effect of (a) catalyst species, (b) catalyst concentration in the wetting solution, (c) peak voltage during FJH, and (d) capacitance density applied during FJH, respectively, on the diameter of F1DMs, as determined by SEM images. The mean diameter is indicated by dots, and the 95% confidence interval is indicated by error bars. The lines connecting the means of each sample are provided to guide the eye. [Figure 5-2] Figure 5B shows confidence interval plots examining the effect of (a) catalyst species, (b) catalyst concentration in the wetting solution, (c) peak voltage during FJH, and (d) capacitance density applied during FJH on the diameter of F1DMs, as determined by SEM images. The mean diameter is indicated by dots, and the 95% confidence interval is indicated by error bars. The lines connecting the means of each sample are provided to guide the eye. [Figure 5-3] Figure 5C shows confidence interval plots examining the effect of (a) catalyst species, (b) catalyst concentration in the wetting solution, (c) peak voltage during FJH, and (d) capacitance density applied during FJH on the diameter of F1DMs, as determined by SEM images. The mean diameter is indicated by dots, and the 95% confidence interval is indicated by error bars. The lines connecting the means of each sample are provided to guide the eye. [Figure 5-4]Figure 5D shows confidence interval plots examining the effect of (a) catalyst species, (b) catalyst concentration in the wetting solution, (c) peak voltage during FJH, and (d) capacitance density applied during FJH on the diameter of F1DMs, as determined by SEM images. The mean diameter is indicated by dots, and the 95% confidence interval is indicated by error bars. The lines connecting the means of each sample are provided to guide the eye. [Figure 5-5] Figure 5E and Figures 5E-5H are stacked column plots examining the effect of (e) catalyst species, (f) catalyst concentration in the wetting solution, (g) discharge voltage applied during FJH, and (h) capacitance density applied during FJH, respectively, on the morphology of the F1DM, as determined by SEM images. [Figure 5-6] Figure 5F is a stacked column plot examining the effect of (e) catalyst species, (f) catalyst concentration in the wetting solution, (g) discharge voltage applied during FJH, and (h) capacitance density applied during FJH on the morphology of the F1DM, as determined by SEM images. [Figure 5-7] Figure 5G is a stacked column plot examining the effect of (e) catalyst species, (f) catalyst concentration in the wetting solution, (g) discharge voltage applied during FJH, and (h) capacitance density applied during FJH on the morphology of the F1DM, as determined by SEM images. [Figure 5-8] Figure 5H is a stacked column plot examining the effect of (e) catalyst species, (f) catalyst concentration in the wetting solution, (g) discharge voltage applied during FJH, and (h) capacitance density applied during FJH on the morphology of the F1DM, as determined by SEM images. [Figure 5-9]Figure 5I is a stacked column plot examining the morphological composition of the samples used in the vinyl ester composites: a sample obtained after sieving; and a sample obtained from blending two replicates. Each data point in Figures 5A-5D represents 120 individual carbon nanofibers or nanotubes from six randomly selected regions of the sample to ensure accurate averages were obtained. In Figures 5E-5I, 108 randomly selected regions (12 images, each divided into nine equal-area regions) for each sample were imaged and assigned a predominant morphology of either 1D, 2D, or hybrid. The parameters optimized to maximize the occupancy of 1D and hybrid morphologies were 0.1 g / ml Fe(III), a discharge of 200 V, and a capacitance density of 1.46 mF / mg. [Figure 6-1]

[0135] Figures 6A-6D show atomistic simulations of amorphous carbon in contact with Ni nanoparticles and annealed at 3000 K. Figure 6A shows the configuration after the initial pre-annealing. Figure 6B shows the final structure, demonstrating carbon interactions and the initiation of carbon fiber formation via catalytic graphitization. [Figure 6-2] FIG. 6C shows the graphitization levels of total carbon and Ni-affected carbon. [Figure 6-3] FIG. 6D shows the percentage of carbon affected by Ni particles over the course of the simulation. [Figure 7-1]

[0136] Figures 7A-7F show a quantitative comparison of F1DM's utility in composites and sustainability with commercial alternatives. Figures 7A-7B show the mechanical analysis of vinyl ester nanocomposites reinforced with F1DM: (a) bulk-scale compression tests compared to commercial multi-walled carbon nanotubes (MWCNTs), and (b) tensile tests compared to pure matrix materials, respectively. [Figure 7-2]Figures 7A-7B show the mechanical analysis of vinyl ester nanocomposites reinforced with F1DM: (a) bulk-scale compression tests compared to commercial multi-walled carbon nanotubes (MWCNTs), and (b) tensile tests compared to pure matrix material, respectively. [Figure 7-3] Figure 7C shows the (c) cumulative energy demand, (d) global warming potential, and (e) cumulative water use associated with the F1DM synthesis of F1DM via surface wetting or melt-mixing catalyst loading strategies, respectively, compared to the FJH synthesis of 2D flash graphene, which does not require a metal catalyst. [Figure 7-4] Figure 7D shows the (c) cumulative energy demand, (d) global warming potential, and (e) cumulative water use associated with the F1DM synthesis of F1DM via surface wetting or melt-mixing catalyst loading strategies, respectively, compared to the FJH synthesis of 2D flash graphene, which does not require a metal catalyst. [Figure 7-5] Figure 7E shows the (c) cumulative energy demand, (d) global warming potential, and (e) cumulative water use associated with the F1DM synthesis of F1DM via surface wetting or melt-mixing catalyst loading strategies, respectively, compared to the FJH synthesis of 2D flash graphene, which does not require a metal catalyst. [Figure 7-6] Figure 7F shows a comparison of the two FJH syntheses of the F1DM strategies considered in the life cycle assessment compared to life cycle assessments in the literature examining the synthesis of carbon nanotubes or nanofibers. [Figure 8-1]

[0137] Figures 8A-8G show mechanical testing of F1DM and vinyl ester epoxy composites compared to commercial MWCNTs (5% CheapTubes) with a diameter of 50 nm obtained from CheapTubes, as well as 2D flash graphene synthesized by FJH. Figure 8A shows a nanoscale compression test. Figure 8B shows a nanoscale compression test. Figure 8C shows a nanoscale compression test. [Figure 8-2]Figure 8D shows a macroscale compression test. Figure 8E shows a macroscale compression test. [Figure 8-3] Figure 8F shows a macroscale tensile test. Figure 8G shows a macroscale tensile test. [Figure 9-1]

[0138] Figures 9A-9D show representative stress-strain curves for the mechanical tests shown in Figures 8A-8G. Figure 9A shows a nanoscale compression test. [Figure 9-2] Figure 9B shows a macro-scale compression test; [Figure 9-3] FIG. 9C shows a macroscale compression test. [Figure 9-4] FIG. 9D shows a macroscale tensile test. [Figure 10-1]

[0139] Figures 10A-10C are schemes for the life cycle inventory of the FH scenarios considered for synthesizing FIDM compared to the predominant industrial methods. Figure 10A shows the scheme for a common commercial method. [Figure 10-2] FIG. 10B shows the scheme for melt mixing of F1DM and FJH. [Figure 10-3] FIG. 10C shows the scheme for surface wetting of F1DM and FJH. [Figure 11-1]

[0140] 11A-11E show the synthesis of boron nitride nanotubes (BNNTs) by flash Joule heating. Figure 11A is a schematic of the FJH device and BNNT production from an ammonia borane (AB) precursor. [Figure 11-2] FIG. 11B is the temperature measurement curve of the sample during the FJH process. [Figure 11-3] FIG. 11C is the conversion of AB in the melt mixing and FJH process. [Figure 11-4] FIG. 11D is a photograph of a flash device using quartz and polyetheretherketone (PEEK) tubing. [Figure 11-5]FIG. 11E is a photograph of a flash device using quartz and polyetheretherketone (PEEK) tubing. [Figure 12-1]

[0141] Figures 12A-12D show the characterization of BNNTs synthesized by FJH: Figure 12A is the FTIR spectrum of the AB precursor and flashed product. [Figure 12-2] FIG. 12B is a Raman spectrum of the AB precursor and the flashed product. [Figure 12-3] FIG. 12C is the XRD pattern of the AB precursor and the flashed product. [Figure 12-4] FIG. 12D is the B1s spectrum of the AB precursor and the flashed product. [Figure 13-1]

[0142] 13A-13I are SEM images of BNNT product formation. 13A-13C are SEM images of BNNT formation in a quartz tube. 13B is an SEM image of BNNT formation in a quartz tube. 13C is an SEM image of BNNT formation in a quartz tube. 13D is an SEM image of BNNT formation in a PEEK tube. 13E is an SEM image of BNNT formation in a PEEK tube. 13F is an SEM image of BNNT formation in a PEEK tube. [Figure 13-2] Figure 13G is a low-magnification SEM image of a tube-rich region, Figure 13H is a low-magnification SEM image of a sheet-rich region, and Figure 13I is an SEM image of BN sheet formation in a quartz tube. [Figure 14-1]

[0143] Figures 14A-14K are images of BNNTs in the flushed product. Figures 14A-14E are TEM images of BNNTs and BN sheets formed in a quartz tube. Figure 14B is a TEM image of BNNTs and BN sheets formed in a quartz tube. Figure 14C is a TEM image of BNNTs and BN sheets formed in a quartz tube. Figure 14D is a TEM image of BNNTs and BN sheets formed in a quartz tube. Figure 14E is a TEM image of BNNTs and BN sheets formed in a quartz tube. [Figure 14-2] FIG. 14F is a HAADF-STEM image and the corresponding elemental distribution of the BNNTs. [Figure 14-3] Figures 14G-14H are HAADF-STEM images and the corresponding elemental distributions of the BN sheet. Figure 14H is a HAADF-STEM image and the corresponding elemental distributions of the BN sheet. [Figure 14-4] Figure 14I shows a TEM image of the catalyst particles, and Figures 14J-14K show HAADF-STEM images and the corresponding elemental distributions of the bamboo-like structures of BNNTs. [Figure 14-5] FIG. 14K is a HAADF-STEM image and the corresponding elemental distribution of the bamboo-like structure of BNNTs. [Figure 15-1]

[0144] Figures 15A-15D show the total solid-phase synthesis of f-BCN by flash Joule heating. Figure 15A is a schematic of f-BCN formation from BH3NH3 and carbon via FJH. [Figure 15-2] FIG. 15B shows real-time temperature measurements from a sample during the FJH process. [Figure 15-3] FIG. 15C is a time-temperature-transformation diagram showing the dynamic formation of turbostratic structures using ultrafast cooling (>103 K / sec). [Figure 15-4] Figure 15D shows the potential energy profiles of h-BN sheets of various sizes (per atom) along the rotational minimum energy path of stacking from AA' to AB. [Figure 16-1]

[0145] Figures 16A-16J show the spectroscopic analysis and crystal structure of f-BN. Figure 16A shows the FTIR spectra of BH3NH3, f-BN, and commercial h-BN. [Figure 16-2] Figure 16B shows the Raman spectra of BH3NH3 and f-BN. [Figure 16-3] Figure 16C is a representative high-resolution Raman spectrum reporting the E2g peak positions of f-BN and commercial h-BN. [Figure 16-4]Figure 16D shows a statistical study of E2g peak positions for f-BN and commercial h-BN. Sample size N=100. [Figure 16-5] FIG. 16E is a scheme showing the structures of h-BN and t-BN. [Figure 16-6] FIG. 16F shows the XRD spectra of f-BN and commercial h-BN. [Figure 16-7] Figures 16G-16H are high-resolution XPS spectra of commercial h-BN and f-BN. Figure 16G is the B1s spectrum. [Figure 16-8] Figure 16H is the N1s spectrum. [Figure 16-9] Figure 16I is an HR-TEM image of the f-BN sheet. [Figure 16-10] Figure 16J shows the BF-STEM, HAADF-STEM images and the corresponding elemental distribution of the f-BN sheet. [Figure 17-1]

[0146] Figures 17A-17I show mechanical peel testing of f-BN. Figure 17A shows SEM images showing tape peel results for (a) f-BN and (b) commercial h-BN, respectively. [Figure 17-2] Figure 17B shows SEM images showing tape peeling results for (a) f-BN and (b) commercial h-BN, respectively. [Figure 17-3] Figure 17C shows the particle size distribution of f-BN and commercial h-BN by tape peeling method. Sample number N=100. [Figure 17-4] FIG. 17D shows SEM images showing the results of unidirectional mechanical shearing of (d) f-BN and (e) commercial h-BN, respectively. [Figure 17-5] Figure 17E shows SEM images showing the results of unidirectional mechanical shearing of (d) f-BN and (e) commercial h-BN, respectively. [Figure 17-6] Figure 17F shows the particle size distribution of f-BN by unidirectional mechanical shearing method and commercial h-BN. Sample number N=100. [Figure 17-7]Figure 17G shows TEM images of (g) f-BN and (h) commercial h-BN after bath sonication, respectively, both placed on top of a lacy carbon grid. [Figure 17-8] Figure 17H ​​shows TEM images of (g) f-BN and (h) commercial h-BN after bath sonication, respectively, both placed on top of a lacy carbon grid. [Figure 17-9] Figure 17I shows the layer number distribution of f-BN after bath ultrasonic treatment. Sample number N=16. [Figure 18-1]

[0147] Figures 18A-18D show electrochemical corrosion resistance tests of f-BN composites. Figure 18A shows (a) Bode plots and (b) Tafel plots of the electrochemical analysis of bare Cu, Cu-PVA, Cu-PVA-h-BN, and Cu-PVA-f-BN in 3.5 wt% NaCl (aq), respectively. [Figure 18-2] FIG. 18B shows (a) Bode plots and (b) Tafel plots of the electrochemical analysis of bare Cu, Cu-PVA, Cu-PVA-h-BN, and Cu-PVA-f-BN in 3.5 wt % NaCl (aq), respectively. [Figure 18-3] FIG. 18C shows (c) Bode plots and (d) Tafel plots of the electrochemical analysis of bare Cu, Cu-PVA, Cu-PVA-h-BN, and Cu-PVA-f-BN in 0.5 M H2SO4, respectively. [Figure 18-4] FIG. 18D shows (c) Bode plots and (d) Tafel plots of the electrochemical analysis of bare Cu, Cu-PVA, Cu-PVA-h-BN, and Cu-PVA-f-BN in 0.5 M H2SO4, respectively. [Figure 19-1]

[0148] Figures 19A-19D show electrochemical LPR tests of different coating materials in 3.5 wt% NaCl (aq): (a) bare Cu, (b) Cu-PVA, (c) Cu-PVA-h-BN, and (d) Cu-PVA-f-BN, respectively. [Figure 19-2]19A-19D show the electrochemical LPR tests of different coating materials in 3.5 wt% NaCl (aq): (a) bare Cu, (b) Cu-PVA, (c) Cu-PVA-h-BN, and (d) Cu-PVA-f-BN, respectively. [Figure 20-1]

[0149] Figures 20A-20H show the characterization of f-BCN with different chemical compositions: Figure 20A is a schematic diagram of f-BCN with varying atomic ratios. [Figure 20-2] FIG. 20B shows the elemental distribution of different f-BCN samples. [Figure 20-3] FIG. 20C shows the valence band maximum (VBM) of different f-BCN samples. [Figure 20-4] FIG. 20D shows the interlayer spacing and surface area of ​​different f-BCN samples. [Figure 20-5] FIG. 20E shows the TEM image and Moiré pattern of f-BCN-30. [Figure 20-6] FIG. 20F shows the corresponding FFT results. [Figure 20-7] Figure 20G is an HR-TEM image showing the in-plane crystallinity of f-BCN-30. [Figure 20-8] Figure 20H shows HAADF-STEM, BF-STEM images, and the corresponding elemental distribution of f-BCN-30 sheets. The scale bar is 20 nm. [Figure 21]

[0150] FIG. 21 shows the boron-carbon-nitrogen ternary phase diagram before heat treatment. [Figure 22]

[0151] Figures 22A-22B show a schematic diagram of the general workflow of the synthesis process of heteroatom-doped reflashed graphene (FG) from (a) metallurgical coke (MC) and (b) bituminous activated carbon (BAC), respectively, by flash Joule heating (FJH). [Figure 23]

[0152] FIG. 23 shows a schematic diagram of a flushing vessel used in one embodiment of the present invention. [Figure 24]

[0153] Figures 24A-24B show a schematic diagram of the input and output of the flushing vessel. The reflash doping process consists of two separate flushing reactions (shown in Figures 24A-24B, respectively). [Figure 25-1]

[0154] Figures 25A-25C show spectroscopic analysis of N-doped BAC flash graphene. Figure 25A shows the average of 100 Raman spectra (with standard deviation). Figure 25B shows a high-resolution Raman spectrum exhibiting TS1 and TS2 peaks, which are positive indicators of turbostraticity. Figure 25C shows an XPS spectrum in which the nitrogen peaks are deconvoluted based on their bond type. Here, the nitrogen content was measured to be greater than 5%. [Figure 25-2]

[0154] Figures 25A-25C show spectroscopic analysis of N-doped BAC flash graphene. Figure 25A shows the average of 100 Raman spectra (with standard deviation). Figure 25B shows a high-resolution Raman spectrum exhibiting TS1 and TS2 peaks, which are positive indicators of turbostraticity. Figure 25C shows an XPS spectrum in which the nitrogen peaks are deconvoluted based on their bond type. Here, the nitrogen content was measured to be greater than 5%. [Figure 26]

[0155] Figure 26A shows an SEM image and EDX elemental analysis of N-doped flash graphene, Figure 26B shows an SEM image and EDX elemental analysis of N-doped flash graphene, and Figure 26C shows an SEM image and EDX elemental analysis of N-doped flash graphene. [Figure 27]

[0156] Figures 27A-27B show spectroscopic analysis of N-doped MC reflashed graphene. Figure 27A shows the average of 100 Raman spectra (with standard deviation). Figure 27B shows the B XPS spectrum in which the nitrogen peaks are deconvoluted based on their bond type. [Figure 28]

[0157] FIG. 28 shows a summary of the reflash doping results. DETAILED DESCRIPTION OF THE INVENTION

[0079]

[0158] The present invention relates to flash joule heating (FJH) for the production of one-dimensional (1D) carbon and / or boron nitride nanomaterials, as well as 1D materials integrated with 0D, 1D, 2D, and 3D nanomaterials, composites, nanostructures, networks, and mixtures thereof. Materials produced by such FJH include 1D carbon and hybrid nanomaterials, boron nitride nanotubes (BNNTs), turbostratic boron-carbon-nitrogen (BCN), heteroatom-doped (substituted) graphene, and heteroatom-doped (substituted) reflashed graphene.

[0080] Synthesis of one-dimensional (1D) carbon and hybrid nanomaterials by FJH

[0159] In embodiments, the present invention relates to the conversion of plastics into 1D and hybrid graphitic 1D / 2D materials with controllable morphologies. The process utilizes in situ catalysis, allowing for directional control over the assembly of mobile carbon in FJH. The produced F1DMs demonstrate excellent mechanical behavior in vinyl ester composites due to their hybrid morphology, demonstrating the value and utility of upcycled products from waste plastics. Furthermore, FJHs offer considerable advantages over classical 1D synthesis when analyzed using a life cycle assessment from a production-to-use perspective.

[0081]

[0160] Graphitic one-dimensional (1D) and hybrid nanomaterials represent a powerful solution for composite and electronic applications due to their excellent properties, but large-scale synthesis of hybrid materials has yet to be realized. This scalable process produces graphitic 1D materials from polymers using flash Joule heating (FJH). This avoids lengthy chemical vapor deposition and does not require solvents or water. Flash 1D materials (F1DM) synthesized using various earth-abundant catalysts have controllable diameters and morphologies by adjusting the parameters. Furthermore, this process can be modified to form hybrid materials in which F1DM is bonded to turbostratic graphene. In nanocomposites, F1DM outperforms commercially available carbon nanotubes. Compared to current 1D material synthesis strategies using life cycle assessment (LCA), FJH synthesis represents an 86–92% reduction in cumulative energy demand and a 92–94% reduction in global warming potential. FJH offers a cost-effective and sustainable route for upcycling waste plastics into useful 1D and hybrid nanomaterials.

[0082] Synthesis of F1DM

[0161] Recently, flash Joule heating (FJH) has been identified as an efficient method for the solvent-free synthesis of carbonaceous and inorganic nanomaterials, where electrical energy and resistance are driven to rapidly (0.05–3 seconds) generate high temperatures (approximately 3,000 K), thereby enabling the solvent-free upcycling of low-value waste materials into high-value products [Luong 2020; Yao 2016; Xie 2018]. Graphite 1D and hybrid nanomaterials are often grown via the deposition of mobile carbon onto metal nanoparticles, and FJH is known to efficiently produce mobile carbon, which has motivated research into the growth of 1D nanomaterials using FJH.

[0083]

[0162] Introducing low concentrations of simple, earth-abundant transition metal salts into a carbonaceous polymer feedstock leads to the in situ catalytic growth of graphitic 1D materials during the FJH process. See the schematic diagram shown in Figure 1A. Iron(II) chloride, nickel(II) chloride, cobalt(II) chloride, and ferrocene were used as growth catalysts. The polymer feedstock was chosen due to the abundance and low cost of waste plastics and the resulting yield of F1DM. The resistivity of the reaction mixture was easily controlled by adjusting the amount of conductive carbon additives, such as carbon black or metallurgical coke. The high resistivity of the plastic precursor allows for many high-resistance junctions between particles in the sample, resulting in high overall and local temperatures. The FJH systems (and parameters) that can be utilized may be based on the systems described and illustrated in Tour Patent Application No. 2021 / 0206642 (hereinafter No. 642) and Tour PCT Application No. WO2022 / 067111 (hereinafter No. 111), with modifications discussed below.

[0084]

[0163] Polymer feedstock may be loaded with catalyst particles via surface wetting or melt mixing. For surface wetting, the polymer may be sonicated in an aqueous alcohol solution containing 0.1 g / ml of salt, then filtered and dried to coat the polymer surface with a small amount of catalyst. For solvent-free catalyst loading, melt mixing can be used, in which a metal complex such as ferrocene and a polymer with a similar melting point are mechanically mixed in the molten state without the use of a solvent. Scanning electron microscope (SEM) images (SEM image 102 in Figure 1A and SEM images in Figures 1B-1C) show that fibers of various diameters are formed during the FJH process. A typical aspect ratio of 330 was observed, but this may be an underestimate, as the entire entangled length often cannot be continuously tracked.

[0085]

[0164] In one embodiment, F1DM was synthesized using a flash Joule-heated reactor as described in Tour's '642 and Tour's '111 PCT applications. Specifically, catalyst-loaded polymer feedstocks were prepared by surface wetting or melt mixing. Regarding the surface wetting method, a solution of an 80 / 20 v / v mixture of water and ethanol was prepared, and the selected salt was dissolved in the solution. For example, a solution of FeCl3 at a concentration of 0.1 g / ml. Five grams of raw or waste polymer with a particle size of less than 0.1 mm was then immersed in the solution and sonicated for 15 minutes. The polymer containing the salt solution was vacuum filtered to remove excess salt solution. The polymer was dried at room temperature overnight to obtain the catalyst-loaded polymer. This results in a slight color change depending on the salt used.

[0086]

[0165] Regarding the melt mixing method: Ferrocene was used as a catalyst due to its low melting point of 173°C. The heater in the melt mixer was set to 175°C. A mixture of 4.95g of HDPE and 0.05g of ferrocene was melt mixed until homogeneous using the heated zone melt mixer of a Braebender 350-E. The melt mixture was then cooled to room temperature and ground to a fine powder using an electric hammer mill.

[0087]

[0166] The catalyst-loaded polymer resulting from surface wetting or melt mixing was then mixed with the conductive additive. Amorphous carbon black (Cabot) was used for all samples herein except where specified, where metallurgical coke has been used as a cheaper alternative.

[0088]

[0167] When amorphous carbon black was used as a conductive additive, 20 wt% of it was ground with a polymer loaded with 80 wt% catalyst. Due to its small particle size, the amorphous carbon black evenly coated the polymer. Carbon black, despite its higher cost compared to waste plastic, is an alternative feedstock to metallurgical coke, a coal-derived product that costs $150 / ton, and this also proved effective.

[0089]

[0168] Because metallurgical coke has a larger particle size of approximately 150 μm, a higher weight percentage must be used to achieve similar final sample conductivity. For use as a conductive additive, 40 wt% was used and mixed with a 60 wt% catalyst-loaded polymer. The particle size of both the polymer and the conductive additive can affect the ratio of polymer feed to conductive additive. The conductive additive and polymer were mixed manually using a mortar and pestle. 0.20 g of the homogeneous mixture was then loaded into an 8 mm inner diameter quartz tube, and the sample was compressed in the quartz tube with a graphite electrode to contain the powder.

[0090]

[0169] The sample was then loaded into the FJH reactor and a capacitor was connected to allow discharge through the resistive sample. An initial sample resistance of 6-8 Ω was used for the samples described herein. The sample was sealed in a vacuum desiccator at approximately 20 mmHg to promote outgassing of heteroatoms and volatiles. An FJH current discharge pulse of the desired voltage was then fully discharged through the sample using the desired capacitance, lasting 1-3 seconds depending on the voltage and capacitance, with higher capacitance resulting in longer durations. The circuit was fully closed for 5 seconds, with a typical discharge lasting only 1-3 seconds. The voltage on the capacitor was allowed to fully discharge; this may require multiple discharges. A bright flash can be observed from the sample due to the production of blackbody radiation.

[0091]

[0170] After FJH, the sample resistance decreased to 0.6–1 Ω. The F1DM was removed from the quartz tube, ground using a mortar and pestle, and characterized without further purification. The yield of F1DM ranges from 40–60 wt% of the reactant recovered as graphite product, depending on the parameters, polymer type, particle size, and amount of conductive additive used.

[0092]

[0171] Quantitatively distinguishing between graphitic carbon forms can be a challenging task, as 1D and 2D forms appear nearly identical in common analytical techniques such as XPS and TGA, while Raman and powder XRD reveal only minor differences. Because the morphologies obtained during FJH are combined, extensive SEM imaging was used to determine the morphological occupancy of each sample. Because 1D and 2D forms can appear similar at low magnification, 108 different images of each sample across nine different regions were examined and the predominant morphology (1D, 2D, or hybrid) was assigned. This allows for quantitative determination of the morphological percentage in area percent. Area percent is used herein when discussing the morphology yield of F1DM. A maximum of approximately 65% ​​of the solid product is 1D morphology, with the remainder comprising 2D turbostratic graphene. Figures 1D-1F show high-resolution TEM images of ribbon-like carbon nanofibers, graphitic bamboo-like carbon, and multiwalled carbon nanotubes. Bamboo-like carbon nanofibers, with many layers stacked in a cup-like fashion, comprise the predominant FIDM morphology. The 2D morphology present was observed through TEM imaging. Graphene nanoribbons, which may result from the unwinding of carbon nanotubes at high temperatures, were also observed through TEM imaging.

[0093] F1DM characterization

[0172] F1DM was characterized using Raman spectral mapping, which demonstrated highly graphitic features over a large area. When F1DM was compared to a control sample containing no metal but with all other conditions identical, both samples yielded a product with 97-98% graphite features. The graphite content was determined by three different characterization methods, including Raman spectroscopy, TGA, and high-resolution XPS. Large-area Raman mapping was performed on a 4 mm 2 This was done by collecting 100 unique spectra over an area of ​​1000 m2, then processing them using a MatLab script to characterize the spectra. In this case, an I2D / IG ratio >0.3 indicates graphiticity. TGA may also be used, where amorphous carbon decomposes below 550°C, and graphitization can be determined by measuring the thermally stable mass at this temperature in an air atmosphere. High-resolution XPS and fitting of the C1s peak allow for the determination of graphite characteristics, and the more accurate C KLL XPS method can also determine graphite content.

[0094]

[0173] High-resolution long-term exposure scans revealed the presence of radial breathing mode peaks in the F1DM sample. This indicates the presence of carbon nanotubes in the F1DM sample but not in the metal-free control sample. Figure 2A (plots 201-202 for the control (no catalyst) and F1DM, respectively); Figure 2B (plots 211-212 for the control (no catalyst) and F1DM, respectively). By varying the Raman excitation wavelength, different radial breathing mode peaks can be observed. Low-intensity M, TS1, and TS2 peaks can also be observed. Figure 2C (plots 221-222 for the control (no catalyst) and F1DM, respectively).

[0095]

[0174] The M peak is at 1750 cm -1 The TS1 and TS2 peaks are located at 1875 cm, respectively. -1 and 2050 cm-1 The M peaks were arranged in a direction parallel to the axial direction, indicating disordered turbostratic stacking. [Merlen 2017; Chen I 2021]. The presence of both the M and TS peaks indicated the presence of both aligned and misaligned stacking of graphitic domains. The presence of the M peak was unexpected because flash graphene is turbostratic. [Luong 2020; Wyss I 2022]. Catalytically synthesized plate- and ribbon-like carbon nanofibers often demonstrate rotationally ordered AB stacking, which may be indicative of the presence of the M peak, further indicating the presence of bulk nanofiber morphology in F1DM. [Carozo 2011; Brar 2002].

[0096]

[0175] Powder X-ray diffraction (XRD) was used to characterize the bulk F1DM product. Figure 2D (plots 231–233 for the starting material, control (no catalyst), and F1DM, respectively) shows a broad, intense, multi-Lorentzian (002) peak, indicative of a graphitic structure. The F1DM (002) peak is fitted by two distinct Lorentzians occurring at 26.46° and 26.11°. See Figure 2E (plots 241–242 for the control (no catalyst) and F1DM, respectively). The (002) peak of the catalyst-free control sample is fitted with a single Lorentzian centered at 26.12°. Graphitic 1D materials, such as MWCNTs and CNFs, have diffraction patterns nearly identical to those of 2D graphene because they share the same unit cell. The only difference is the layer spacing of turbostratic graphene (0.35 nm) compared to that of graphitic 1D material (0.34 nm), which is reflected by the position of the (002) peak. A lattice spacing of 0.350 nm corresponds to a diffraction peak at 26.1°, while a decrease in the lattice spacing is expected to result in a shift of the diffraction peak to higher angles. Fitting the F1DM (002) peak with two separate Lorentzian functions indicates that both 1D material and turbostratic graphene are present in the sample, whereas the single peak in the control sample corresponds only to turbostratic graphene. It is also known that the position of the (002) peak depends on the diameter of the carbon nanotube or nanofiber, and that the position of the (002) peak can be fitted by multiple subpeaks [Singh 2010].

[0097]

[0176] Furthermore, as can be observed in large diameter carbon nanotubes, an enhanced (101) peak at 45.3° is also observed in F1DM but not in the catalyst-free control (Figure 2F, plots 251-252 for control (no catalyst) and F1DM, respectively). [Singh 2010] X-ray photoelectron spectroscopy (XPS) was used to determine the elemental content and bonding of F1DM (Figure 10a). During FJH, the high-boiling carbon content of the plastic is enriched to 97.8% in the graphitic product. High-resolution spectra of the C1s transition reveal minimal oxygen content and a π-π transition located at 291 eV. * The D parameter of the starting polymer is 12.8 eV, which increases to 20.2 eV after FJH, which corresponds to the sp 3 Mixed to SP 2 Thermogravimetric analysis of F1DM under air atmosphere shows a high decomposition temperature of 630°C, which confirms the characteristics of bulk graphite.

[0098]

[0177] The detection limit of an XPS survey scan is typically 0.5–1.0 at%. Therefore, with concentrations determined by ICP-MS of up to 0.3 wt%, one would not expect to detect any signal in an XPS survey scan. Furthermore, the penetration depth of XPS detection is only 1–2 nanometers. It is possible that iron photoelectrons were not detected because TEM imaging indicates that iron resides in nanoparticles beneath the many layers of carbon in graphite.

[0099]

[0178] In contrast, iron is solubilized after sample digestion to prepare it for ICP-MS testing, resulting in a lower detection limit for ICP-MS. Inductively coupled plasma mass spectrometry (ICP-MS) analysis revealed that F1DM formed using a surface wetting method with 0.1 g / ml FeCl3 on virgin high-density polyethylene (HDPE) feedstock showed an Fe content of only 0.3 wt% in the starting material, which decreased to 0.06 wt% during FJH. The reduction in catalyst content during the FJH process could be attributed to sublimation of metal ions and gas evolution at high temperatures [Deng 2021]. The catalyst content could be further reduced to <10 ppm by washing with 1 M HCl.

[0100] F1DM from virgin, post-consumer mixed plastics

[0179] 27 million tons of mixed waste plastics are landfilled annually. We converted post-consumer mixed waste plastics into F1DM by grinding, surface wetting, and FJH. Figures 3A-3F show that mixed waste plastics composed of HDPE, low-density polyethylene (LDPE), polypropylene (PP), polystyrene (PS), and polyethylene terephthalate (PET) can be easily upcycled into F1DM by a 3-second long FJH pulse. Figure 3A is a Raman spectrum showing F1DM derived from mixed waste plastics characterized by a large-area Raman average spectrum (plot 301), and the inset shows the radial breathing mode (plot 302). Figure 3B is a powder XRD comparing the waste plastic (plot 311) with the synthesized F1DM (plot 312). Figure 3C is a survey and high-resolution XPS (plots 321-322). Figures 3D-3F are SEM images showing the morphology of F1DM derived from waste plastics.

[0101]

[0180] Other recent studies have described the synthesis of graphitic 1D materials from waste plastics [Williams 2021; Wang 2022; Jie 2020]. However, these methods often rely on a two-step, two-hour pyrolysis followed by a catalyst-assisted chemical vapor deposition process, have not been shown to be compatible with mixed waste plastic streams, and can result in mixtures consisting of approximately 30 wt% amorphous carbon or a significant excess of catalyst, which must be further removed [Tripathi 2017; Wu 2016].

[0102]

[0181] The mixed waste plastic mixture used consisted of 42% HDPE, 20% PP, 20% LDPE, 10% PS, and 8% PET, mimicking the composition of terrestrial plastic waste. Pyrolysis and FJH or PET are known to result in lower carbon yields and lower yields of 1D graphitic materials [Algozeeb 202; Yao 2022]. The conversion of polystyrene was further investigated because some studies have reported that aromatic structures result in thicker CNTs [Yao 2022]. This trend was also observed for F1DM. For the waste-derived F1DM, a radial breathing mode (Figure 3A) can be observed, as determined by powder XRD (Figure 3B) and TGA. The complete conversion of the waste plastic to a graphitic structure is also observed. In Figure 3B, an enhanced (101) peak can also be observed, confirming the presence of bulk F1DM from the mixed waste plastic.

[0103]

[0182] The high elemental purity in the produced F1DM can be further studied by XPS (Figure 3C, which shows a 2% increase in oxygen content compared to HDPE-derived F1DM, despite the inclusion of PET, which is 25 wt% oxygen). Additives such as colorants, plasticizers, adhesives, or residual waste from the primary use of the plastic are considered impurities.

[0104]

[0183] TGA and XRD (Figure 3B) of the mixed waste plastics show no substantial metal impurities, as indicated by the low residual TGA mass and minimal unidentified XRD peaks. The atomic carbon in these impurities can be converted to graphene, while heteroatoms such as oxygen, metals, or halides are sublimated and removed. The morphology of the F1DM, including the hybrid morphology, can be observed by SEM imaging, as shown in Figures 3D-3F.

[0105]

[0184] The particle size of the waste polymer feedstock has been shown to affect the results of FJH [Algozeeb 2020], with finer particle sizes allowing for higher catalyst loadings and higher surface areas of high-resistance junctions, improving F1DM yield. Therefore, the F1DM yield in post-consumer polymer samples can be further increased by improving grinding. While the mixed waste plastics were ground as finely as possible with the hammer mill used, industrial scaling would allow for smaller particles, resulting in a larger F1DM surface.

[0106]

[0185] Many types of polymers exist, and the high melting temperatures of some may not allow catalysts to be introduced via melt mixing. To demonstrate the generality of the process, polyurethane, a thermosetting polymer, was converted to F1DM via a simple surface wetting technique. F1DM synthesized from these waste polyurethanes demonstrated similar properties and morphologies to those derived from virgin HDPE. The polyurethane-derived F1DM exhibited slightly increased oxygen (2.3%) and nitrogen (1.4%) content, indicating the formation of heteroatom-doped 1D and hybrid morphologies via FJH, which has already been demonstrated with FJH graphene [Chen 2022].

[0107] Controllable Hybrid and F1DM Forms

[0186] 1D and 2D hybrid materials, such as graphene for rebar applications, are desirable due to their novel mechanical and electronic properties [Vedhanarayanan 2018; Yan 2014]. However, these materials are synthesized almost exclusively via multi-step chemical vapor deposition methods, which are costly and low-yield [Xia 2017; Zhao 2012]. FJH produced regions of 2D graphene morphology, F1DM morphology, and commonly observable regions of colocalization and fusion between 1D and 2D morphologies. Figures 4A-4I.

[0108]

[0187] SEM imaging demonstrates F1DMs with edges decorated with 2D graphene sheets, with 1D forms sometimes extending edge-to-edge across the entire 2D graphene (Figures 4A and 4C-4D). A region of the sample (Figure 4B) also displayed the coalescence of 1D forms into larger diameter 1D material, followed by a network of 2D graphitic forms. TEM imaging (Figures 4E-4I) demonstrates the colocalization of F1DMs and graphene. Figure 4F is a high-resolution TEM image of the highlighted region 441 in Figure 4F. The circled region 442 highlights the lattice fringes between the bamboo-like carbon nanofibers and graphene sheets, indicating that they are part of the same crystal lattice. Figure 4H is an atomic resolution TEM image of the highlighted region 461 in Figure 4G, showing the hexagonal arrangement of carbon atoms in the graphene sheets, uninterrupted at the junction between the 1D and 2D forms.

[0109]

[0188] High-resolution imaging (Figures 4E-4G) showed that the lattice fringes and edges were uninterrupted from the outer walls of the nanofibers to the larger graphene sheets, indicating van der Waals interactions connecting the 1D and 2D domains together. Atomic-resolved TEM imaging (Figure 4H) revealed that the hexagonal sp 2The hybridized graphene sheets were revealed to be uninterrupted across the edges at the junctions between the 1D and 2D morphologies, suggesting a covalently linked hybrid material. Fast Fourier transform (FFT) (Figure 4I) indicates AB stacked graphene, and the M peaks in XRD and Raman spectroscopy (Figures 2A-2F) suggest that the hybrid material may exhibit a reduced crystal lattice spacing.

[0110]

[0189] FJH parameters such as discharge voltage, catalyst type, loading, and capacitance density can affect the product morphology. Capacitance density is defined herein as the system capacitance per unit mass reacted [Beckham 2022]. SEM analysis revealed that catalyst loading and type affected the diameter of the F1DM produced (Figures 5A-5B), with decreasing catalyst loading producing thinner 1D materials. Fe(III) produced the thinnest F1DM, while Co(II) produced the thickest.

[0111]

[0190] It is well known that the type of catalyst can have a substantial impact on the size of the CNTs produced, as different metals have different catalytic graphitization rates and carbon solubility [Yuan 2008; Thambiliyagodage 2018; Hunter 2022]. Consistent with this specification, many literature reports suggest that iron is more effective than cobalt or nickel in some cases due to these effects. FJH parameters, such as capacitance density and pulse voltage, are directly correlated with the capacitive current via equation (1) and affect the diameter of the F1DM (Figures 5C-5D). In the following equations, I, C, V, and t correspond to current, capacitance, voltage, and time, respectively. I = C d(V) / d(t) (1)

[0191] Interestingly, capacitance and pulsed voltage discharge produced opposite trends in F1DM diameter, even though both contributed additional charge to the reaction. However, because the capacitor discharge rate was not uniform, doubling the capacitance would not be expected to double the current, but instead would double the discharge time. The time required for the capacitor to discharge can be determined by using equation (2), where R represents resistance. t = C * R * log(V) (2)

[0192] Increased peak discharge voltage allows for increased instantaneous current discharge through the sample, resulting in higher overall power and heating rates. The nonmonotonic correlation of capacitance density and discharge voltage with diameter was unexpected but was thought to indicate a shift in mechanism. This has previously been observed in machine learning-guided partial dependence analyses of FJH studies, which found that increasing current density results in a shift from reaction-limited to diffusion-controlled kinetics [Stanford 2020; Beckham 2022]. This shift in growth kinetics is common in crystalline materials and can be observed here as well [Carroll 2018; Viswanatha 2007]. Representative SEM images of F1DM with parameter variations demonstrated that F1DM formation is parameter-sensitive, allowing for control of product morphology.

[0112]

[0193] Qualitative analysis also demonstrated that catalyst type, loading, capacitance density, and discharge voltage can be used to control the morphological composition of F1DM (Figures 5E-5H). The use of Ni(II) resulted in the highest occupancy of 2D material, while Co(II) produced the most hybrid material. As catalyst loading decreased, the amount of hybrid and 1D forms produced also decreased, likely due to a lower density of catalytic sites for mobile carbon deposition (Figure 5F). As the power input to the system via applied voltage or capacitance density increased, the amount of 1D and hybrid material increased. The diameter of the F1DM product positively correlated with the amount of hybrid forms present. Optimized reaction parameters yielded 68% 1D / hybrid forms (Figure 5I). Using iterative mixing or sieving, the yield of F1DM was further increased to 90%.

[0113]

[0194] When the catalyst is loaded onto or into the plastic and the conductive CB reaches a lower temperature, only the polymer feedstock forms the F1DM form, while the conductive additive is thought to form the 2D form. The conductive additive may be essential for the FJH process to reduce the sample's resistance and enable high-power discharge. To increase the yield of the 1D form, iterative mixing can be used. In this case, in a second FJH reaction, the F1DM product (50 / 50 1D and 2D forms) is used as the conductive additive, increasing the 1D occupancy to approximately 75% without degrading quality. The use of larger particle-size conductive additives, such as metallurgical coke, allows for the use of simple sieving to separate the smaller F1DM product from the larger particle-size conductive additive. Sieving or iterative mixing allows for the production of F1DM composed of 80-90% 1D and hybrid forms without the use of solvents or centrifugation-based separation methods.

[0114] Mechanism of F1DM formation

[0195] Catalyst-loaded conductive additives do not result in the formation of F1DM, but do surface-modify the 2D graphene morphology with metal nanoparticles. The highly resistive junctions and volatile decomposition imparted by the plastic feedstock may be essential for F1DM formation. These junctions are thought to form hot spots that facilitate F1DM nucleation. To further analyze this effect, homogeneous samples with similar overall resistivity and density were tested and evaluated. Ash obtained from industrial pyrolysis of plastic waste has a similar resistivity of 7 Ω to the carbon-doped F1DM feedstock, but is homogeneous. Metal salts were introduced into the pyrolysis ash using surface wetting, and the sample was subjected to FJH using the same parameters used to form F1DM. No 1D morphology was observed by SEM and TEM imaging, indicating that resistive junctions at the plastic surface are necessary for the formation of 1D morphology.

[0115]

[0196] To further determine whether resistive junctions are the mechanistic cause of F1DM formation, we replicated this process using sand (silica) instead of plastic. All parameters remained identical, including wetting the sand surface to introduce the catalyst, mixing with the carbon black conductive additive, and FJH setup. After FJH, the samples were ground and sieved to remove residual inert silica. Results showed graphitization of the carbon black, along with minor SiC formation, with <20 area% of the carbon converted to F1DM, while the remainder was converted to 2D graphene form.

[0116]

[0197] This study demonstrated that resistive junctions may be necessary for the formation of F1DM, but carbon from plastics may also be important for producing large quantities of F1DM. Recent studies have shown that carbonization in the presence of carbon black or other conductive amorphous carbons can result in the formation of turbostratic carbon nanoparticles without metal catalysts [Jia 2022]. Amorphous carbon can be converted to graphene sheets as a minor by-product during CNT formation [Gog 2013]. This further supports the observation that 2D graphene sheets have been produced from carbon black.

[0117]

[0198] TEM images revealed the presence of metal nanoparticles in the base of the plastic-derived F1DM. The lattice spacing matched that of the metal oxides in the original catalyst used, indicating that during the FJH process, high temperatures lead to the decomposition of metal salts, thereby forming nanoparticles that facilitate the deposition of mobile carbon, which then nucleate and form thermodynamically favorable graphitic domains that extend into the F1DM. At lower catalyst loading concentrations, fewer or smaller nanoparticles are expected to form, resulting in the formation of 2D graphene morphology, which explains why the morphology and diameter of the F1DM change with catalyst concentration.

[0118]

[0199] Similarly, the type of salt catalyst is expected to determine the decomposition temperature at which catalytic nanoparticles form and the rate of nanoparticle formation, which will affect F1DM formation. Because both metal and metal oxide nanoparticles are known to catalyze the growth of CNF and CNT materials, it is unclear whether the nanoparticles formed in situ during the FJH reaction are metal or metal oxide. The catalytically active species is thought to be a neutral metal species, which is then converted to the oxide when the sample is removed from the FJH reactor and exposed to air. Because metal or metal oxide catalytic nanoparticles are formed in situ during the FJH reaction, it is expected that there is no need to add costly catalysts, such as noble metal nanoparticles often used in CVD processes, to the reaction scheme.

[0119]

[0200] To better understand the relationship between catalyst concentration and F1DM diameter, TEM imaging was used to determine the change in catalytic nanoparticle size as catalyst concentration increased. These results showed that decreasing catalyst loading concentration resulted in a decrease in catalytic nanoparticle size and a decrease in F1DM diameter. At high metal salt loadings, some catalytic nanoparticles were visible even without the surrounding F1DM coating. This indicated that the catalyst concentration in the wetting solution controlled the size and abundance of the nanoparticles formed.

[0120]

[0201] Catalysis of Fe, Ni, and Co particles in the synthesis of 1D carbon structures is commonly considered under CVD conditions, where the carbon-containing feedstock material deposits on the surface of nanoparticles, diffuses through the particles, and is incorporated into the growing graphitic domains [Fouquet 2012]. Most previous studies have focused on carbon nanotube formation from gaseous sources, while catalytic graphitization of amorphous carbon remains unexplored [Wang 2007]. Previous studies have demonstrated that premature termination of the FJH reaction results in a carbonized product with significant amorphous content and significant graphitic crystal lattice disorder, suggesting the presence of an amorphous intermediate between the polymer and the graphitic product [Algozeeb 2020]. Furthermore, the resulting morphology was not exclusively 1D, as is typically obtained from the catalytic pyrolysis of plastics, but rather a hybrid morphology, elucidating the possibility of a different mechanism. The solid amorphous intermediate can be converted to a 1D graphitic product on catalytic nanoparticles.

[0121]

[0202] To investigate the effect of metal inclusion within the FJH setup, the behavior of amorphous carbon domains in contact with Ni nanoparticles (Figure 6A) was examined via molecular dynamics. Figure 6A shows the configuration after an initial pre-annealing, already showing that some carbon atoms of the amorphous carbon 602 have dissolved within the Ni nanoparticles 601. The system was heated and maintained at 3000 K for 4 nsec to simulate the high temperatures of the FJH. The amorphous carbon underwent thermal and catalytic graphitization, both promoted by the high FJH temperature. Catalytic graphitization involves the dissolution of carbon atoms from both the amorphous and already partially graphitized domains into the Ni particles, which then deposit on the surface, forming large 1D or hybrid graphitic domains (Figure 6B). Figure 6B shows the final structure and indicates the initiation of carbon fiber formation via carbon interaction and catalytic graphitization, as indicated by arrow 613.

[0122]

[0203] The large size of the catalytic nanoparticles (450 Ni atoms) resulted in a carbon product with a large diameter, which differs from existing literature results [Chiang 2009]. By analyzing the graphitization kinetics, we determined that this catalytic process promoted the conversion of amorphous carbon (Figures 6C-6D), and that the curvature and size of the metal nanoparticles favored the formation of 1D and hybrid morphologies. Figure 6C (Ni-affected and total plots 621-622, respectively) shows the graphitization levels of total carbon and Ni-affected carbon, demonstrating the catalytic effect that Ni atoms have on the graphitization of affected carbon atoms. Figure 6D shows the percentage of carbon affected by Ni particles over the simulation, demonstrating the interaction of mobile carbon with the Ni catalyst even over short simulated timescales.

[0123] Usefulness in nanocomposites

[0204] Due to their high tensile strength, thermal and electrical conductivity, and low density, both 1D and 2D graphite morphologies can be utilized in composite materials. Hybrid materials can offer superior mechanical properties because the 2D morphology increases adhesion at the interface between the nanomaterial and the matrix.

[0124]

[0205] F1DM is highly dispersible in 1% Pluronic surfactant aqueous media, allowing concentrations up to 1.63 mg / ml. Various amounts of ground F1DM powder were weighed into centrifuge tubes, and solvent was added to obtain an initial loading concentration (approximately 1 mg of F1DM powder per ml of solvent). The tubes were then sonicated for 10 minutes in a cup horn sonicator (Cole-Parmer Qsonica 448) and centrifuged for 5 minutes at 550 relative centrifugal force to remove larger aggregates. After centrifugation, the supernatant was decanted and diluted 100-fold, as graphene concentrations lead to very high absorbance. The absorbance of the solution was measured at 660 nm. Beer's law was used to calculate the absorbance of 66 L g -1 cm -1 The concentration was determined using an extinction coefficient of .

[0125]

[0206] Seven grams of F1DM was produced to test loadings of 0.5, 2, and 5 wt%. F1DM was readily dispersible in the vinyl ester matrix material after brief cup horn sonication. Vinyl ester (VE) resin was obtained from Fiberglass Supply Depot and used as received. Methyl ethyl ketone peroxide (MEKP) was obtained from Fiberglass Supply Depot and used as received as a catalyst / curing agent for the resin. F1DM / VE composites were prepared by combining 5.0 g of vinyl ester with 20–200 mg of F1DM, depending on the desired loading, in a 20 mL scintillation vial. The solution was then mixed at 300 rpm for 30 minutes using a magnetic stirrer. After stirring, the solution was mixed and sheared at approximately 10,000 rpm for 5 minutes using a Cole-Parmer homogenizer (Tissue Tearor 986370-07 homogenizer; 120 VAC, 1.2 A). Five drops (approximately 0.15 g) of MEKP were then added to the solution while stirring with a magnetic stir bar at 300 rpm for 5 minutes. The solution was then poured into a PDMS mold coated with a release agent and allowed to cure overnight.

[0126]

[0207] Nanocomposites of vinyl ester resin reinforced with F1DM were tested using nanoindentation and demonstrated a dramatic increase in compressive modulus even at 0.5 wt%, resulting in a 21% increase. Macroscale mechanical testing showed substantial improvements under tension and compression (Figures 7A-7B), with F1DM composites exhibiting 92%, 130%, and 48% increases in tensile strength and 174%, 304%, and 63% increases in toughness at 0.5, 2, and 5 wt%, respectively.

[0127]

[0208] The decrease in mechanical properties as the loading increases from 2% to 5% is likely the result of F1DM aggregation in the vinyl ester matrix material. It is well known that nanocomposites do not exhibit a linear increase in mechanical properties with increasing reinforcement loading, but typically have an optimal maximum at loadings below 5% [Medupin 2019; Roy 2018]. The interphase properties of polymer nanocomposites are complex and directly affect macroscale mechanical properties, which may depend on the surface area, aspect ratio, and dispersibility of the nanomaterial, the viscosity of the matrix material, and the interfacial interactions between the phases [Ashraf 2018; Zare 2016].

[0128]

[0209] The properties of vinyl ester loaded with F1DM were compared to those of commercially available carbon nanotube-loaded vinyl ester composites prepared using conventional methods (Figure 7A). F1DM outperformed the commercial nanotubes tested in nanoindentation and macroscale compression tests (Figure 7A), which may be due to the hybrid morphology and high graphite purity, while F1DM improves the properties of the pure vinyl ester matrix material (Figure 7B).

[0129]

[0210] To demonstrate the advantages of F1DM over graphene produced by catalyst-free FJH, the best-performing sample (5% F1DM) was compared to a similarly prepared sample containing 2D graphene produced by 5% FJH. Figures 8A-8G and 9A-9D show that F1DM outperforms graphene produced by flash Joule heating in nanoindentation tests. Figures 8A-8C show nanoscale compression tests, Figures 8D-8E show macroscale compression tests, and Figures 8F-8G show macroscale tensile tests. Figure 9A (plots 901-905 for blank, 0.5% F1DM, 2% F1DM, 5% F1DM, and 5% CT, respectively) shows nanoscale compression tests. Figure 9B (multiple plots 911-913 of pure VE, 0.5% CHEEPTUBE in VE, and 0.5% F1DM in VE, respectively) and Figure 9C (multiple plots 921-923 of pure VE, 2% CHEEPTUBE in VE, and 2% F1DM in VE, respectively) show macroscale compression tests, and Figure 9D (multiple plots 931-934 of 0% F1DM in VE, 0.5% F1DM in VE, 2% F1DM in VE, and 5% F1DM in VE, respectively) show macroscale tensile tests.

[0130]

[0211] The superiority of F1DM over graphene produced by flash Joule heating in nanoindentation tests can be attributed to the hybrid morphology of F1DM, which improves the matrix penetration and strain propagation properties of vinyl esters. Therefore, the F1DM hybrid morphology is shown to be mechanically superior to both 1D and 2D graphitic carbon nanomaterials as additives in vinyl esters.

[0131]

[0212] 1D graphite nanomaterials are well known for their conductivity, a property that is often exploited in nanocomposites. Accordingly, the conductivity of the produced F1DM / vinyl esters was measured as shown in Table I, demonstrating an increase in conductivity with increasing loading; however, commercial MWCNTs are superior to F1DM as a conductive additive. This may be a result of the longer aspect ratio of commercial MWCNTs compared to F1DM.

[0132] [Table 1]

[0133] Life cycle assessment from production to use

[0213] Because the impacts of application and removal are expected to vary negligibly based on the synthesis method of graphitic 1D materials, a life cycle assessment from production to use was performed to examine the FJH method of F1DM synthesis.

[0134]

[0214] Regarding the scope, goal, functional unit, and inventory of the life cycle assessment, a production-to-use life cycle assessment is a systematic analysis of the demand and impacts associated with a product, from the raw materials required for synthesis to the processing and manufacturing of the product, without examining the final end-use application of the waste or the disposal of the product. The specific goal of the life cycle assessment herein was to evaluate the demand and environmental impacts resulting from FJH production of F1DM for comparison with literature benchmarks studying the production of graphite 1D materials synthesized using other methods. The system is considered here to cover three major processes: raw material production, reaction feed preparation, and FJH reaction. Raw material transportation is not considered here, and the process is assumed to be at a laboratory scale. The functional unit considered here is 1 kg of high-purity graphite 1D material powder with a graphite content of >95%, as this is the purity level typically sold for gram-scale or larger applications, such as composites or coatings. The environmental impacts of waste polyethylene production were not considered here; however, costs associated with the collection and separation of post-consumer waste polyethylene were included. [Martin-Lara 2022]. The direct energy input for the FJH process was experimentally measured and the cumulative demand and impacts were calculated using Argonne National Laboratory's GREET life cycle assessment.

[0135]

[0215] The surface wetting method used raw HDPE powder wetted with 4 L of an 80 / 20 v / v water / EtOH solution per kg of polymer. This was bath sonicated for 15 minutes, and 75% of the solution was recovered by centrifugation. The polymer mixture was air-dried and mixed with 20 wt% carbon black using a ball mill. The salt-loaded polymer and conductive additive mixture was then subjected to FJH and used without further purification to obtain 1 kg of a hybrid form of F1DM with a carbon and graphite content of >95%. Alternatively, the melt mixing method considered waste polyethylene containing iron acetylacetonate at a loading of 0.25 wt%. The homogeneous melt mixture was cooled, ground to a 1 mm particle size using an electric hammer mill, and then mixed with 33 wt% metallurgical coke (particle size 3 mm) to obtain a conductive mixture. The mixture was then FJH'd, extruded through a quartz tube, and sieved to separate the F1DM from the metallurgical coke, yielding a highly pure 1D form with a carbon and graphite content of over 95%. Given that all utilized databases (e.g., GREET, SimaPro, Ecoinvent, and Gabi) followed International Organization for Standardization best practice, direct comparison of our life cycle assessment with other literature values ​​was possible.

[0136]

[0216] A general scheme and life cycle inventory for the industrial synthesis of nanotubes is shown in Figures 10A-10C. Figure 10A shows the scheme for a general commercial process, Figure 10B shows the scheme for melt blending and FJH for F1DM, and Figure 10C shows the scheme for surface wetting and FJH for F1DM. This life cycle assessment considered two different synthesis scenarios: melt blending of waste polymers and surface wetting of virgin polymers, to determine cumulative energy demand, global warming potential, and cumulative water use (Figures 7C-7E).

[0137]

[0217] The F1DM synthesis was compared with FJH2D graphene synthesis from post-consumer waste plastics, which does not require catalyst loading. [Wyss II 2022]. The F1DM synthesis using surface wetting consumed 683 MJ and 185 L of water and produced 27 kg of CO2 equivalents per kg of graphite product. Most of the impact was attributed to the raw polymer and conductive additives. When considering the melt-mixing scenario, the process used 395 MJ and 111 L of water but produced 26 kg of CO2 equivalents per kg of graphite product. Impacts resulting from the synthesis of waste polyethylene were ignored, but collection and separation costs were considered. In the waste polymer melt-mixing scenario, most of the impact was attributed to FJH.

[0138]

[0218] Comparing the FJH synthesis of graphitic 1D and hybrid materials to the literature was complicated by the wide variety of morphologies produced. Single-walled nanotubes were not considered comparable products; only multi-walled nanotubes or nanofibers were compared. Comparing the FJH synthesis of F1DM to an International Organization for Standardization-compliant life cycle assessment of graphitic 1D materials demonstrated a reduction in both energy use and global warming potential to synthesize 1 kg of graphitic 1D material. Figure 7F shows a comparison of the FJH synthesis of two F1DM strategies considered in the life cycle assessment compared to a literature life cycle assessment examining the synthesis of carbon nanotubes or nanofibers. Table II provides values ​​and references for the plotted data in Figure 7F, comparing the cumulative energy demand (CED) and global warming potential (GWP) of the F1DM strategy (which are within ellipse 701) with a literature life cycle assessment (LCA) examining the synthesis of MWCNTs and CNFs (which are within block 702). The units of CED are MJ / kg, while the units of GWP are g of CO2 equivalents per kg of product.

[0139] [Table 2]

[0140]

[0219] The literature average production-to-use energy demand to form 1 kg of graphite 1D material is 4,855 MJ, while the average global warming potential is 355 kg CO2 equivalents, with the FJH pathway representing an 86-92% reduction in cumulative energy demand and a 92-94% reduction in global warming potential.

[0141] More adaptability

[0220] FJH can rapidly and controllably synthesize a variety of valuable graphitic 1D or hybrid materials with proven value in an inexpensive, sustainable, and efficient manner using simple, earth-abundant salts and waste plastics. Furthermore, FJH can be doped or functionalized.

[0142] Boron nitride nanotube (BNNT) synthesis by FJH

[0221] In an embodiment, the present invention further relates to the synthesis of BNNTs by using the flash joule heating (FJH) process. The process is carried out in the solid phase under moderate reaction pressure (1 atm Ar) and temperature (approximately 1800 K), and no solvent is used. Ammonia borane (AB) and nickel(II) bis(acetylacetonate) (Ni(acac)2) can be used as the precursor and catalyst, respectively. The products, primarily BNNTs and h-BN, can be directly separated from the conductive additive after synthesis.

[0143]

[0222] Boron nitride nanotubes (BNNTs), known as structural analogs of carbon nanotubes (CNTs), have attracted significant attention due to their excellent intrinsic properties and wide range of applications. Despite their potential, rapid synthesis of BNNTs with high yield and quality remains challenging, limiting their practical application. Using an all-solid-phase catalytic flash Joule heating method (a catalytic growth process), BNNTs can be synthesized in less than one second, resulting in high yield and selectivity of BNNTs and BN nanosheets. The product can be directly separated from conductive additives such as carbon or metal powders. This further provides continuous, scalable synthesis of BNNTs using the FJH method and opens up the possibility of catalytic synthesis of other materials.

[0144]

[0223] f-BCN with various chemical compositions and turbostratic characteristics can be synthesized from BH3NH3 and carbon black in less than one second using the ultrafast, solvent-free FJH method. The atomic percentage of carbon can be controlled from approximately 0% to approximately 100%, and spectroscopic analysis indicates that the VBM can be adjusted accordingly. At lower carbon percentages, f-BN becomes extremely close to t-BN in its spectroscopic characteristics. Calculations confirm the existence of a turbostratic structure, along with an energy barrier that hinders its transformation into a well-ordered counterpart. The resulting f-BCN layers with disordered orientation are easily exfoliated. Compared to commercial h-BN nanoplates, f-BCN samples demonstrate stable dispersibility in aqueous Pluronic solutions (F-127, 1 wt% in deionized water).

[0145]

[0224] Furthermore, the addition of f-BCN as a barrier filler in PVA nanocomposites shows better compatibility, imparting higher erosion protection efficiency. The turbostratic morphology of f-BCN is difficult to reproduce using common bottom-up methods such as CVD and hydrothermal processes, where the cooling rate is 100-1000 times lower than that of FJH. The FJH method offers a high-yield process for synthesizing bulk quantities of turbostratic materials.

[0146] Synthesis of BNNTs by FJH

[0225] Ammonia borane (AB) was chosen as a representative precursor for synthesizing BNNTs by FJH because its decomposition at various temperatures has been studied and provides both B and N in stoichiometric ratios. AB has been extensively studied as a monolayer h-BN precursor in CVD [Tay 2014; Stehle 2015; Koepke 2016]. Suib et al. demonstrated that the decomposition of AB resulted in semicrystalline h-BN [Frueh 2011]. Prior to h-BN growth, it is common to perform low-temperature decomposition of AB to generate polymeric radical species and borazines, which have higher reactivity in CVD. The BN bond is maintained during decomposition, but H undergoes a gradual loss. The FJH system (and parameters) that can be utilized may be based on the systems described in Tour's 642 and Tour's 111 PCT applications, with modifications as discussed below. [See also Luong 2020; Chen 2022; Deng 2022].

[0147]

[0226] In an embodiment of the present invention, a schematic diagram of the device and temperature curves are shown in Figures 11A-11B. In a typical FJH process, a mixture of AB, Fe(acac)3 / Ni(acac)2 catalyst, and metallurgical coke (metcoke) is compressed inside a quartz tube between two graphite rods. The two graphite electrodes were connected to a capacitor bank with a total capacitance of 60 mF. The current passing through the sample was then measured after rapid discharge under different voltages. The real-time temperature can be measured using an infrared sensor as plotted (Figure 11B). The heating rate can be up to 5 x 10 3K / sec. To reduce the carbon content in the product, metcoke (12–20 mesh, or 840–1680 μm) was used instead of carbon black powder as a conductive additive. The large particle size of metcoke allows for convenient separation by sieving, and the weight loss of metcoke at reaction temperatures is negligible. AB and its decomposed species are susceptible to oxidation at high temperatures. To reduce oxygen contamination, O-ring seals were used on both electrodes in the quartz tube, and Ar was used as a protective atmosphere. AB and Ni(acac)2 were mixed and heated to 110 °C to ensure uniform melt mixing (Figure 11C). Two types of tubes can be used in the FJH process (Figures 11D–11E).

[0148]

[0227] For example, in a typical experiment, ammonia borane was mixed and ground with 3 wt% Ni(acac)2 and 3 wt% Fe(acac)3 and heated to 120 °C for 10 minutes. The mixture was then mixed with metcoke in a 1:1 mass ratio. The reactants were added to a quartz tube (inner diameter 8 mm and outer diameter 12 mm). Graphite rods were used on both sides of the quartz tube as electrodes, with copper wool between the graphite rods and the electrodes. The tube was sealed with two O-rings and loaded into a jig. Ar gas (approximately 1 atm) was used as an inert atmosphere to prevent sample oxidation during the FJH reaction. A capacitor bank with a total capacitance of 60 mF was charged by a DC power supply. The discharge time was controlled by an Arduino controller relay with a programmable millisecond-level delay. The optimized conditions for BNNT synthesis were 90 V, 500 ms, twice. After the FJH reaction, the apparatus was evacuated and cooled to room temperature. The flashed product was sieved through a 40-mesh sieve (425 μm metric) to separate the metcoke and BNNT / BN product. The mass yield is about 45% of the theoretical BN yield for the quartz tube and about 60% for the PEEK tube. About 30% of the product is in the form of tubular structures, and the remainder is sheet-like structures.

[0149] Characterization of BNNTs

[0228] Spectroscopic and imaging techniques were used to confirm the formation of BNNTs in the flashed product. Figures 12A-12D. In the FTIR spectrum, the flashed product exhibited a peak at 1317 cm -1 It shows a BN stretching peak at 780 cm -1 The bending peaks of BNB are shown in Figure 12A (with plots 1201-1202 of the AB precursor and flashed product, respectively). The peaks match those in commercial h-BN. Some peaks match those of the AB precursor, indicating the presence of a small amount of AB.

[0150]

[0229] The Raman peaks of the AB precursor are absent in the flashed product. Figure 12B (with plots 1211-1212 of the AB precursor and flashed product, respectively). 2g The peak is at about 1361 cm in plot 1212. -1 This is due to the E 2g Peak (approx. 1368cm -1 ) is lower than that of the tubular structure. 2g This may be due to the hardening of the mode [Arenal 2006].

[0151]

[0230] In the XRD pattern, the AB precursor peak disappeared in the product. Figure 12C (showing the AB precursor and flushed product, respectively). In plot 1222, the peak at 26.0° corresponds to the characteristic (002) diffraction peak of BN, and the peaks at 43.4° and 44.5° correspond to the (100) and (001) diffraction peaks. The broadened peaks suggest the formation of BN sheets; the BNNTs are not highly crystallized. The BNNTs also showed a broadened (002) peak compared to h-BN materials in previous reports. [Lee J 2021; Kim H 2021]

[0152]

[0231] The B1s spectrum confirmed the purity of the BN product. Figure 12D (with plots 1231-1232 for the AB precursor and flashed product, respectively) shows that AB absorbs water quickly in air, so slight oxidation may be observed in the AB precursor (approximately 10%). In the flashed product, only BN bonds are present, with no obvious B-O and B-C bonds formed. The B / N ratio is approximately 1.06.

[0153]

[0232] The formed BNNT structures can be seen in SEM images (Figures 13A-13I). BNNTs were found in both the quartz tube (Figures 13A-13C) and the PEEK tube (Figures 13D-13F), demonstrating that tube growth is independent of an external container. Multiwalled BNNTs exhibited both hollow and solid morphologies in the samples. However, the tubular structures formed in the PEEK tube exhibited a higher hollow fraction, which may be due to the higher pressure that can be maintained in the PEEK tube. High pressure promotes selectivity for BNNTs to BN sheets and BNNT crystallinity [Bae 2022]. The length and diameter of the BNNTs were 20-50 μm and 50-100 nm, respectively. This was observed with approximately 30% selectivity in the flushed product, with the remainder of the product being sheet-like BN structures (Figures 13H-13I).

[0154]

[0233] Two types of BNNT morphologies could be distinguished in the TEM images. The tubes without obvious hollow structures exhibited diameters of 30–50 nm, while the hollow tubes exhibited diameters of 50–100 nm. TEM analysis showed the presence of crystalline domains in the outer regions of the BNNTs. The layer spacing of 0.353 nm was slightly larger than that of crystallized h-BN (0.333 nm). This result is in good agreement with the broadened (002) and shifted peaks in the XRD patterns. The increased lattice spacing is expected to shift the diffraction peaks to higher angles.

[0155]

[0234] Figures 14A-14B also show BN sheets (lateral size of approximately 100 nm). The obvious edge interference fringes suggest the excellent crystallinity of the few-layer BN nanosheets. Bright-field (BF) and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) images, along with elemental mapping, show the presence of B and N in the BNNTs and BN nanosheets (Figures 13G-13I), which is consistent with the XPS results.

[0156] catalysis

[0235] Catalysis techniques at FJH are discussed above with respect to the synthesis of 1D carbon materials. The use of suitable catalysts allows for enhanced reaction rate and selectivity. Various types of catalysts were used during synthesis to investigate catalytic decomposition and catalytic action in the BNNT growth process. No obvious tubular structure formation was observed during reactions using metal borides, metal chlorides, or metal powders as catalysts, suggesting that catalysis may be different in the CVD method from the BNNT growth process.

[0157]

[0236] The combined Ni(acac)2 / Fe(acac)3 catalyst was found to show enhanced selectivity for sheet versus tubular structures. Elemental mapping of HAADF-STEM images confirmed the presence of the Ni / Fe catalyst (Figure 14K). The primary decomposition products of Fe(acac)3 at approximately 400°C are Fe2O3 / Fe3O4. [Kim H 2021; Toyos-Rodriguez]

[0158]

[0237] Metal oxide particles can be found at the head of the BNNTs. The growth mode follows the typical VLS mechanism in CVD. The growth mechanism of BNNTs during the FJH process is believed to be as follows: active BN species are first formed, which evaporate during a rapid dehydrogenation process over 200 °C, followed by the decomposition of Ni(acac)2 / Fe(acac)3 into metal oxide particles at approximately 400 °C. The final dehydrogenation step from NHBH(s) to BN(s) requires high temperatures exceeding 1200 K [Demirci 2020]. Semicrystalline h-BN was found to form at approximately 1500 K [Frueh 2011], and the h-BN morphology resembles BN sheets in our flashed product. BNNTs begin to grow in the temperature window of 1500–1800 K. The rapid dehydrogenation and high local BN species concentration allow for selectivity to BNNTs instead of h-BN. A comparison of FJH-synthesized BNNTs with other BNNT synthesis methods is listed in Table III. The FJH method reduces the cost of producing BNNTs on a large scale by reducing the reaction temperature, pressure, and duration.

[0159] [Table 3]

[0160] Turbostratic boron-carbon-nitrogen (BCN) synthesis by FJH

[0238] In an embodiment, the present invention further relates to the synthesis of BCN with turbostratic structure and high in-plane crystallinity via an all-solid-state flash joule heating (FJH) system, which involves short pulses of high electrical energy followed by rapid cooling (10 s), all in less than 1 s. 3 ~10 4 Starting with BH3NH3 and carbon black, the FJH-product is termed flash BCN (f-BCN-x, where x is the percentage of carbon in the reactants). Other conductive powder additives, such as iron and tungsten, can also be used to replace carbon black.

[0161]

[0239] The atomic percentage of carbon can be controlled from approximately 0% to approximately 100% by varying the carbon content in the reactants, as determined via X-ray photoelectron spectroscopy (XPS). At lower carbon percentages, closely spaced spectroscopic features are observed relative to those of pure turbostratic h-BN (t-BN).

[0162]

[0240] f-BCN possesses a turbostratic arrangement, which facilitates its delamination by various mechanical methods, such as adhesive tape peeling, unidirectional mechanical shearing, and bath sonication. Computational results indicate the existence of an energy barrier to convert the turbostratic structure to its well-ordered counterpart.

[0163]

[0241] Hexagonal boron nitride (h-BN) and graphene are two common layered materials whose interlayer interaction is about 26 meV / atom (about 2.5 kJ / mol) [Rydberg 2003], while the in-plane binding energy is about 450 kJ / mol, which is more than two orders of magnitude larger than the interlayer interaction. Therefore, the formation of turbostratic materials with high in-plane crystallinity can be controlled by thermal annealing followed by an ultrafast cooling process. Thermal annealing facilitates the formation of an ordered in-plane structure. [2] , the ultrafast cooling process preserves the locally poorly aligned stacking order rather than the global energy minimum. This can be extended to doped graphene as well.

[21] .

[0164]

[0242] Compared to commercial h-BN and graphene, f-BCN has better transient stability when dispersed in aqueous Pluronic solutions (F-127, 1 wt% in deionized water). Polyvinyl alcohol (PVA) nanocomposites containing 10 wt% f-BCN coated on copper foil impart improved corrosion resistance when exposed to 0.5 M sulfuric acid or 3.5 wt% saline solutions.

[0165] Synthesis of f-BCN

[0243] 15A illustrates an ultrafast, all-solid-phase preparation process based on FJH for synthesizing f-BCN in less than one second. As previously discussed herein, FJH systems (and parameters) that can be utilized may be based on the systems described in Tour's '642 and Tour's '111 PCT applications, with modifications as discussed below.

[0166]

[0244] In a typical flash process, a mixture of BH3NH3 and commercial carbon black is slightly compressed inside a quartz tube between two copper electrodes. BH3NH3 is chosen as the reactant because it serves as both a boron and nitrogen source and has preformed BN bonds in the precursor. Carbon black simultaneously acts as a carbon source and a conductive agent during the reaction. A capacitor bank in the circuit is used to provide electrical heating energy to the reactants.

[0167]

[0245] By varying the carbon content in the mixture, the FJH process can be used to synthesize f-BCN with various compositions and turbostratic structures. During a typical flash reaction with a voltage of 150 V and a sample resistance of approximately 40 Ω, the current passing through the sample reaches approximately 15 A during a discharge time of approximately 600 ms. The total electrical energy is 3.1 kJ / g, and the energy cost to convert one ton of BH3NH3 precursor into flash product is currently approximately $19. The real-time temperature can be measured using an infrared sensor, as plotted in Figure 15B. The temperature reaches approximately 1220 K within approximately 600 ms, with a ramp rate during the heating phase estimated at approximately 1300 K / s, followed by a rapid cooling rate of approximately 1600 K / s.

[0168]

[0246] Other carbon-free conductive additives, such as tungsten and iron, were also tested, resulting in flash products named f-BN-W and f-BN-Fe, respectively. Specifically, the iron powder could be collected by a magnet and reused. This resulted in the formation of BN without any obvious carbon signal.

[0169]

[0247] Because of the potential catalytic effect of Cu during the reaction, a graphite spacer was used as an alternative to the Cu wool plug. The diameter of the graphite spacer was approximately 1 mm smaller than that of the quartz tube to facilitate gas generation and avoid tube explosion. BN was prepared using such a graphite spacer.

[0170]

[0248] Previous pyrolytic dehydrogenation analyses have reported that there are three pyrolytic steps to form BN-based structures from the BH3NH3 precursor [Frueh 2011], and that the overall reaction is highly exothermic (-171 kJ / mol). Although the third step, dehydrogenation of NHBH(s) to BN(s), has a high reaction rate barrier and requires higher temperatures, typically 1200-1400 K, this drives the reaction to completion [Demirci 2020; Frueh 2011]. The thermochemical equation is shown in Equation (3): BH3NH3(s)=3H2(g)+BN(s) Δ f H θ =-171.1kj / mol (3)

[0171]

[0249] There are three stepwise pyrolysis steps (shown in Eqs. (4)-(6)) to form BN crystals from the BH3NH3 precursor [Frueh 2011], and the overall reaction is highly exothermic. The third step in Eq. (6), the dehydrogenation of NHBH(s) to BN(s), is the rate-limiting step and requires higher temperatures, typically 1200-1400 K. BH3NH3(s)=H2(g)+H2B=NH2(s)(343K~373K)(4) H2B=NH2(s)=H2(g)+HBNH(g)(393K~403K)(5) HBNH(g)=H2(g)+BN(s)(1200K~1400K)(6).

[0172]

[0250] Compared to other bottom-up methods such as CVD [Xu D 2018; Tan 2015] and hydrothermal methods [Ding 2021; Ding 2019], which involve much slower cooling rates, typically below 10 K / s, resulting in the formation of well-ordered stacked morphologies, the FJH method has a 100–1000 times faster cooling rate, producing turbostratic BCN (t-BCN), as shown in Figure 15C. Simulations performed using the finite element method (FEM) show that the temperatures reached in the bulk of the sample are sufficient to promote the third decomposition step because the time scale of uniform energy input is relatively short compared to that of thermal diffusion.

[0173]

[0251] Nudged elastic band (NEB) simulations were performed to study the thermodynamic stability of the in-plane rotation by using h-BN as an example. Figure 15D (1.3 × 1.3 nm, respectively) 2 , 1.7×1.7nm 2 , 2.0×2.2nm 2 , 2.5×2.6nm 2 , 4.3×4.5nm 2 , 5.6×5.8nm 2 , and 6.8 × 6.9 nm 2 Plots 1501-1507 in Fig. 15 show the potential energy profiles of h-BN sheets with different sizes along the rotational minimum energy path from AA' to AB stacking. All potential energies were normalized by the total number of atoms in the small h-BN sheet and are relative to the most stable AA' stacking mode. Calculations show that (1) t-BN is generally about 0.5 kJ / mol higher in energy than AA' stacked h-BN. The energy difference can be larger when the h-BN sheets are very small; (2) the smallest h-BN sheet (1.3 × 1.3 nm) 2(3) Except for (3), all other energy profiles show an energy barrier for realignment from turbostratic (rotation angle ≠ 0° or 60°) stacking to AA' or AB stacking. This realignment energy barrier explains the metastable nature of t-BN; (4) the slope of the energy profile near 0° is steeper for larger h-BN sheets. This is because, even with a small rotation angle, larger h-BN sheets have more opportunities for interlayer misalignment (e.g., N on N or B on B, leading to large electrostatic repulsion). The realignment energy barrier per atom is nearly independent of size (approximately 0.054 kJ / mol = 0.56 eV for AA' and approximately 0.039 kJ / mol = 0.40 eV for AB), as listed in Table IV. (In other words, the realignment energy barrier for the entire h-BN sheet is proportional to the total number of atoms and the sheet area.) Therefore, the formation of BN-based turbostratic structures is kinetically possible and can be achieved by the FJH method using ultrafast heating and cooling processes.

[0174] [Table 4]

[0175] Spectroscopic analysis and crystal structure of f-BCN

[0252] When a mixture of BH3NH3 and 20 wt% carbon black was used as reactants, the flash product exhibited spectroscopic features similar to h-BN. Therefore, f-BCN-20 (or any f-BCN-x, where x is less than or equal to 20) is also referred to as flash BN (f-BN) in this context. BH3NH3 and f-BN can be analyzed by Fourier transform infrared spectroscopy (FTIR); note that there were no interfering peaks of carbon black or flash graphene (FG) in the IR [Luong 2020]. As shown in Figure 16A, there were no obvious NH or BH stretching bands in the f-BN product (with plots 1601–1603 for BH3NH3, f-BN, and h-BN, respectively), indicating complete conversion of BH3NH3 [Frueh 2011]. The f-BN product exhibits the BN stretching peak (E 1u Maud, approximately 1353cm -1 ) and the bending peak of BNB (A 2u Maud, approximately 782cm -1 ) [Zou 2019], which is similar to the spectrum of commercial h-BN. -1 The shoulder peak at is due to the BC band.

[0176]

[0253] The FTIR results are consistent with the Raman spectra in Figure 16B (with plots 1611-1612 for BHNH and f-BN, respectively). -1 There are many Raman peaks for BH3NH3 at 1000 MHz, whereas these peaks are absent in f-BN and the characteristic E 2g The E peak appears in the Raman spectrum compared to bulk h-BN. 2g The peak shows a blue shift as the number of layers decreases, indicating shorter BN bonds and E 2g Approximately 4cm for hardening of the mode -1 A blue shift of 100% was observed [Gorbachev 2011;Cai 2017].

[0177]

[0254] From the representative high-resolution Raman spectra shown in Figure 16C (with plots 1621-1622 for f-BN and h-BN, respectively), the characteristic E 2g Approximately 3cm from the peak -1 blueshift and lower integrated intensity I(E 2g ) were found, which resembled the characteristics of few-layer h-BN sheets and showed weak coupling interactions between adjacent layers [Gorbachev 2011].

[0178]

[0255] In Figure 16D, E of 100 different spots in f-BN and h-BN 2g The peak positions were studied (circles 1631-1632 for f-BN and h-BN, respectively). Commercial h-BN belongs to bulk h-BN, and its E 2g Peak is 1365.3cm -1 It is a face-centered lattice with a limited distribution (approximately 0.2 cm -1 , red shaded area). f-BN has a higher average E 2g Peak (approx. 1368.7cm -1 ) and a wider distribution (approximately 2.6 cm -1 ), and about 72% of the area has E, which indicates the general decoupling behavior in f-BN samples. 2g A blue shift of the peak was observed.

[0179]

[0256] The scheme depicted in Figure 16E shows a normal in-plane crystal lattice constant of about 0.25 nm and a layer spacing of about 0.33 nm in well-aligned h-BN crystal 1641. Random translation and rotation of the individual sheets was observed in t-BN crystal 1642, which has a larger average interlayer distance.

[0180]

[0257] In Figure 16F (with circles 1651-1652 for f-BN and h-BN, respectively), the turbostratic nature of the f-BN sample was further investigated by X-ray diffraction (XRD). The (002) diffraction peak became broader but less intense and shifted to a lower angle from approximately 26.7° to 26.1°, indicating an approximately 2.3% expansion of the layer spacing. In f-BN, the (100) and (101) peaks merged into a broad (10) peak, and long-range-order diffraction peaks such as (110) and (004) were absent. These results confirm the absence of basal plane ordering and the presence of turbostratic structure. [Alkoy 1997; Thomas 1963; Gladkaya 1986]

[0181]

[0258] Elemental analysis performed by XPS showed a B to N atomic ratio of about 1.05 and the presence of 6.7 wt% C. See Table V.

[0182] [Table 5]

[0183]

[0259] High-resolution B1s and N1s spectra showed that typical BN bonds (approximately 190.5 eV) and N-B bonds (approximately 398.2 eV) were dominant. Figure 16G (with plots 1661–1662 for f-BN and h-BN, respectively); Figure 16H (with plots 1671–1672 for f-BN and h-BN, respectively) [Ba 2017; Hu 2019]. A small B-C peak (approximately 187.3 eV) was observed, which coincided with the B-C band shown in the FTIR spectra in Figure 16A. The valence band of f-BN showed a valence band maximum (VBM) of -3.10 eV, which is slightly downshifted compared to the value of commercial h-BN (-2.70 eV). This downshift is caused by the introduction of several O and C atoms into f-CN. The UV-vis spectra of commercial h-BN and f-BN showed an optical band gap of approximately 6.0 eV (Figure S10, Supporting Information). [Ba 2017] Therefore, FJH synthesis may be an effective method for tailoring VBM by introducing heteroatoms.

[0184]

[0260] The Brunauer-Emmett-Teller (BET) method is used to measure the specific surface area of ​​f-BN (approximately 143 m 2 / g) is commercial h-BN (approximately 22m 2 / g), which is about 7 times larger. The larger surface area of ​​f-BN could be a result of the smaller flake size and average number of layers. The larger nanopore distribution could result from the gaps between the smaller flakes. On the other hand, the commercial h-BN sample consisted of thick microplates with more than 10 layers and a well-ordered structure.

[0185]

[0261] The f-BN sheets can reach a maximum lateral size of approximately 4.3 μm and have a wrinkled structure. High-resolution transmission electron microscopy (HR-TEM) analysis showed two stacked f-BN layers. The corresponding fast Fourier transform (FFT) pattern showed the presence of two sets of six-fold diffraction patterns close to each other with a rotational mismatch of approximately 12°, which is attributed to the turbostratic structure of f-BN. Figure 16I (inset 1681) shows the FFT pattern; the scale bar is 5 nm. -1 (It is).

[0186]

[0262] Polycrystalline materials are composed of many crystalline domains of various sizes and orientations, which also produce multiple sets of diffraction patterns. In the case of polycrystalline films, in-plane crystal boundaries separate the individual domains in real space, and the film exhibits multiple sets of diffraction patterns in reciprocal space. Turbostratic materials are solids in which the basal planes are misaligned. Each individual sheet has its own translation and rotation direction in real space and exhibits one set of diffraction patterns in reciprocal space. Therefore, the diffraction pattern of a polycrystalline film arises from the in-plane domains, while the diffraction pattern of a turbostratic material arises from the out-of-plane domains (each individual sheet).

[0187]

[0263] This means that there are several solutions to distinguish between polycrystalline and turbostratic materials by TEM: (1) An inverse Fourier transform can be performed on each set of diffraction patterns in reciprocal space, and the reconstructed image in real space reflects the relative associations between the different sets of spots. Specifically, if the reconstructed image shows crystalline structures from different regions of the same sheet, it belongs to a polycrystalline material; otherwise, it is a turbostratic material. (2) HR-TEM can be performed from the top surface. Moiré patterns can be observed in turbostratic materials, but not in polycrystalline materials. There are many different types of moiré patterns. A moiré pattern produced by a single rotational stacking defect is the simplest type, with a period λ and a rotation angle Θ. With more than two rotation directions, more complex moiré patterns may be observed. (3) Fourier transforms can be performed at different locations on the sample in the same image, and the resulting diffraction patterns can be compared in reciprocal space. Specifically, if all diffraction patterns are not the same (orientation and number of spots), it belongs to a polycrystalline material; otherwise, it is a turbostratic material.

[0188]

[0264] Solutions (2) and (3) were used to demonstrate the turbostratic structure of the flash samples.

[0265] To identify the turbostratic structure [Ci 2010; Warner 2009], atomic HR-TEM imaging was performed from the top surface. In-plane moiré patterns were observed in the few-layer region. Clear interference fringes and FFT patterns indicated that the flash product had excellent crystallinity. FFT patterns were compared at different locations on the same sheet. The consistent orientation and number of diffraction spots ruled out the possibility of polycrystalline matter in this region. Therefore, the various sets of diffraction spots were due to turbostratic structure.

[0189]

[0266] Bright-field (BF) and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) images, together with elemental mapping, showed the presence of B, N, and a small amount of C in the f-BN sheets (Figure 16J), which was consistent with the XPS results.

[0190]

[0267] Plate-like f-BN nanoplates with lateral sizes of 20–50 nm were also observed. HR-TEM images showed the crystalline nature of the f-BN nanoplates, with the majority of these nanoplates being only a few layers thick. The corresponding FFT images showed the presence of at least three sets of six-fold diffraction patterns. The estimated mass yield of f-BN was approximately 34%. The conductive carbon additive could be removed from the f-BN by heat treatment in air. However, oxidation appears to have occurred simultaneously on the surface (see Table VI). The presence of small amounts of BC and BO bonds in f-BN is theoretical, as previous studies have shown that oxidation of BC bonds begins at approximately 600 °C [Hu 2019; Li 2014].

[0191] [Table 6]

[0192] Mechanical peeling test of f-BN

[0268] The turbostratic characteristics of f-BN facilitate its delamination by various mechanical methods such as adhesive tape peeling, unidirectional mechanical shearing, and bath sonication. Table VII.

[0193] [Table 7]

[0194]

[0269] The few-layer f-BN sheets obtained by adhesive tape peeling can be distinguished by a top-view scanning electron microscope (SEM) image shown in Figure 17A. In contrast, due to the strong coupling between adjacent layers in commercial h-BN, no obvious peeling was observed in Figure 17B, and only thick nanoplates of several hundred nanometers were observed. The average lateral sizes of the f-BN obtained by the tape peeling method and the commercial h-BN were 0.40 and 0.34 μm, respectively. Figure 17C (with circles 1701 and 1702 for f-BN and h-BN, respectively) showed that the particle size distribution results indicated that the majority of the f-BN flakes had lateral sizes below 1.0 μm, making them difficult to apply to electronic devices such as field-effect transistors. [Gupta 2020]

[0195]

[0270] However, the advantages of f-BN, such as its nanoscale structure and excellent dispersibility, indicate its potential application as a nanofiller to enhance mechanical properties and improve electrochemical corrosion resistance performance, as discussed below.

[0196]

[0271] The same exfoliation phenomenon can also be observed by applying unidirectional shear force. Mechanical exfoliation of f-BN sheets is demonstrated in Figure 17D, which shows exfoliated f-BN sheets with the same edge structure (represented by the white dotted lines 1711 outlining each sheet). In Figure 17D, the direction of the unidirectional shear force is indicated by arrows 1712. Atomic force microscopy (AFM) profiles showed bilayer to few-layer structures of the exfoliated f-BN sheets. These results demonstrated effective exfoliation of f-BN. In contrast, few-layer BN sheets cannot be prepared directly from commercial h-BN by unidirectional shear under the same conditions (Figure 17E). The average lateral sizes of f-BN and commercial h-BN obtained from the mechanical shear method were 0.47 and 0.40 μm, respectively. Figure 17F (with circles 1721–1722 for f-BN and h-BN, respectively)

[0197]

[0272] Compared with commercial h-BN nanoplates with more than 10 layers, few-layer f-BN flakes with a few hundred nanometers in size and a ripple-like structure were obtained by bath sonication in ethanol without surfactants (Figures 17G-17H). The layer number distribution of f-BN obtained by bath sonication showed that approximately 80% of the f-BN sheets had 3–5 layers (Figure 17I). In some areas, small black particles could be seen, likely originating from the carbon conductive additive. HR-TEM images and corresponding FFT patterns demonstrate the high-quality turbostratic f-BN sheets and the well-ordered structure of commercial h-BN nanoplates.

[0198] Electrochemical corrosion resistance testing of F-BN composite materials

[0273] The turbostratic structure improves the dispersibility and stability of f-BN in aqueous solutions. After dispersion in a Pluronic aqueous solution (F-127) (1 wt % in deionized water), the concentration of f-BN can reach a maximum concentration of approximately 18 wt % higher than that of commercial h-BN. Nevertheless, the percentages of commercial h-BN and f-BN in solution were approximately 6% and 77%, respectively, after 21 days, indicating that the f-BN dispersion has a higher stability over time. The excellent dispersibility of f-BN makes it possible to prepare stable nanocomposites using f-BN as a compatible additive.

[0199]

[0274] Because composite reinforcement relies on interactions between the polymer and the filler surface area, a prerequisite is the dispersion and distribution of nanofillers within the polymer matrix [Luong 2020; Albdullah 2018]. PVA has been studied to test additives that reduce chemical and electrochemical metal erosion [Sarkar 2016; Owuor 2017]. Barrier films provide a tortuous diffusion path for corrosive electrolytes, slowing the metal erosion process. Similarly, they prevent the migration of metal ions, building a local Nernst potential at the polymer-metal interface. The addition of appropriate nanofillers can occupy free volume within the polymer matrix and improve the film's blocking properties [Sarkar 2016].

[0200]

[0275] Further demonstration of f-BN as a filler in PVA composites acting as an electrochemical corrosion-resistant coating is shown in Figures 18A-18D, as f-BN showed excellent dispersibility in aqueous solution.

[0201]

[0276] Prior to electrochemical testing, the coating thickness was characterized by cross-sectional SEM images. The average thickness of the coating layer was approximately 9 μm. Figures 19A-19D show electrochemical linear polarization resistance (LPR) tests of bare Cu, PVA-coated Cu (Cu-PVA), commercial h-BN and PVA composite-coated Cu (Cu-PVA-h-BN), and f-BN and PVA composite-coated Cu (Cu-PVA-f-BN) in 3.5 wt% saline solution. Cu-PVA-f-BN exhibited the highest polarization resistance (Rp), approximately 22.8 kΩ cm. 2 , which was about 47% higher than that of Cu-PVA.

[0202]

[0277] Open circuit potential (E corr ) represents the thermodynamic tendency of an electrode to lose electrons in solution [Warner 2009;Li 2014]. According to the Nernst equation, the measured potential is E corrAt lower E, the metal surface remains relatively stable. Potentiodynamic polarization measurements in Figure 18A (with plots 1801-1804 for bare Cu, Cu-PVA, Cu-PVA-h-BN, and Cu-PVA-f-BN, respectively) and Figure 18B (with plots 1811-1814 for bare Cu, Cu-PVA, Cu-PVA-h-BN, and Cu-PVA-f-BN, respectively) show that Cu-PVA-f-BN exhibits a more positive E corr (-188 mV vs. Hg / HgSO), demonstrating that the surface metal has a lower tendency to participate in the electrochemical oxidation process. Compared with pure PVA and PVA-h-BN composite coatings, the PVA-f-BN composite has a higher erosion protection efficiency (>92%) and better anti-corrosion performance, as shown in Table VIII.

[0203] [Table 8]

[0204]

[0278] The same trend of enhanced corrosion resistance is also observed in 0.5 M H2SO4, as shown in Figure 18C (with plots 1821–1824 for bare Cu, Cu-PVA, Cu-PVA-h-BN, and Cu-PVA-f-BN, respectively) and Figure 18D (with plots 1831–1834 for bare Cu, Cu-PVA, Cu-PVA-h-BN, and Cu-PVA-f-BN, respectively). Cu-PVA-f-BN exhibits the highest polarization resistance (Rp), approximately 10.0 kΩ cm. 2 This is 20 times higher than that of Cu-PVA. The erosion protection efficiency of Cu-PVA-f-BN is >97% compared to 68% for Cu-PVA-h-BN, as shown in Table IX. This further demonstrates the excellent dispersion and compatibility of f-BN in the polymer matrix.

[0205] [Table 9]

[0206]

[0279] Optical and microscopic morphology after electrochemical testing indicated that the Cu under the PVA-f-BN composite coating was least affected, and surface elemental analysis also showed no obvious oxide formation for Cu-PVA-f-BN. These results are consistent with the highest erosion protection efficiency from electrochemical testing and demonstrate one possible application of f-BN as a filler for nanocomposites.

[0207]

[0280] The mechanical properties, such as hardness and Young's modulus, of epoxy resins containing 1 wt% f-BN additive show increases of approximately 54% and 70%, respectively, compared to pure epoxy resins. These improvements cannot be achieved by replacing f-BN with an equivalent amount of commercial h-BN.

[0208] Synthesis of f-BCN with different chemical compositions

[0281] The atomic ratio of carbon can be adjusted by directly varying the weight percentage of carbon black in the reactants. When a mixture of BH3NH3 and 30 wt% carbon black is used as the reactants, the flash product is called f-BCN-30. The same naming convention is used herein for other prepared f-BCN samples. As the weight percentage of carbon increases, the atomic percentage of carbon in the flash product can be controlled from approximately 0% to approximately 100%, as determined by XPS results. Figure 20A (Illustrations 2001–2004 are for f-BN-W, f-BN, f-BCN-50, and f-BCN-100, respectively). Elemental analysis demonstrated a monotonic decrease in B and N from f-BN to f-BCN-100. Figure 20B. High-resolution XPS of the C1s spectrum indicated the presence of C-B and C-N bonds in the f-BCN sample. As the mass ratio of carbon increased, the ratios of C-B and C-N also increased. High-resolution XPS of the B1s and N1s spectra also confirmed the presence of BC and NC bonds.

[0209]

[0282] The presence of BC and NC bonds confirmed the formation of in-plane hybrid structures instead of out-of-plane stacked heterostructures, the latter of which is often more thermodynamically stable. This is due to the ultrafast heating and cooling rates (approximately 10 4 This may be due to the

[0210]

[0283] There are several possibilities for the flash product after the reaction of carbon black with BH3BH3, namely: (1) A mixture of BN and carbon black. (2) Mixtures of NC, BC, BN, and graphene or carbon black. (3) Boron-carbon-nitrogen ternary compounds and carbon black.

[0211]

[0284] High-resolution XPS results reflected the presence of BC, BN, and CN bonds, ruling out the possibility that the product was simply a mixture of BN and carbon black.

[0212]

[0285] In the case of NC and BC, two possibilities exist. First, BC and NC could be boron carbide and carbonitride. Boron carbide has a covalently bonded BC moiety at approximately 187.4 eV in the B1s spectrum, exhibiting a characteristic XRD peak (powder diffraction file 35-0798, B4C). However, deconvolution of the B1s spectrum did not reveal a peak at approximately 187.4 eV, and no characteristic XRD peaks were present, thus ruling out boron carbide as a possible candidate. Similarly, no characteristic XRD peaks for carbonitrides were present (powder diffraction file 50-1250, C3N4), thus ruling out the possibility of carbonitrides. Another possibility for BC and NC is codoped graphene, which can be considered a carbon-rich boron-carbon-nitrogen moiety.

[0213]

[0286] TEM images showed the presence of conductive carbon materials, including some graphite structures, in the flash product. Using f-BCN-30 as an example, the conductive carbon materials had an average size of approximately 25 nm, making them distinguishable from f-BCN-30. This observation indicated that the flash product contained unconverted carbon materials. Therefore, the flash product is a mixture of a boron-carbon-nitrogen ternary compound and carbon black. Due to the presence of conductive carbon materials in the product, the carbon content determined by XPS analysis may be overestimated.

[0214]

[0287] Due to the difference in thermal stability between conductive carbon materials and substitutional carbon species chemically bonded with boron and nitrogen, thermogravimetric analysis (TGA) can be used to oxidize conductive carbon materials. The first derivative of the thermogravimetric curve showed two peaks, starting at approximately 540 °C and 750 °C. The first peak is primarily due to the oxidation of the conductive carbon material. Therefore, the conductive carbon material can be removed from the flash product by controlling the temperature to approximately 675 °C under air conditioning (i.e., the carbon content of the carbon-rich boron-carbon-nitrogen ternary compound may be underestimated). XPS results of various f-BCN samples before and after heat treatment reflect the presence of substitutional carbon species, and the carbon content ratio can reach 35.7 at% in f-BCN-70 after 30 minutes of heat treatment at approximately 675 °C under air conditioning.

[0215]

[0288] The carbon ratio of the in-plane hybrid structure affects the electronic structure and changes the VBM. As the atomic ratio of carbon increases, the VBM of f-BCN changes from -3.10 eV to -1.85 eV. Figure 20C. Raman spectra of different f-BCN samples show the G peak (approximately 1580 cm). -1 , single resonance), D peak (approximately 1350 cm -1 , valley double resonance), 2D peak (approximately 2695 cm -1 , secondary zone boundary phonon), D+G peak (approx. 2930 cm -1 , scattering peak combination), 2D' (approximately 3250 cm-1 ) and G * (approx. 2450cm -1 ) [Huang 2020; Hong 2013; Yoon 2012]. As the carbon ratio in the reactants increased, the intensity of the D+G peak decreased and the 2D peak increased. The intensity ratio between the D and G peaks of f-BCN-70 was approximately 1.10, which is similar to boron and nitrogen co-doped graphene, which belongs to the carbon-rich BCN. f-BCN-100 (FG) showed a high 2D to G ratio (approximately 8) and a low D peak, which is similar to Luong 2020. The introduction of carbon into f-BCN samples also imparted magnetic properties [Sarkar 2016], which differ from commercial h-BN.

[0216]

[0289] h-BN exhibits a diamagnetic response due to the boron bonded to nitrogen, resulting in a net magnetic moment of approximately zero. However, f-BCN-50 has BC / O and N-C / O bonds, which may contribute to the net magnetic moment. f-BCN-50 exhibits a ferrimagnetic response and a small coercivity of approximately 22 Oe. The saturation magnetic moment of f-BCN-50 is 0.115 emu / g. Inductively coupled plasma mass spectrometry (ICP-MS) confirmed that contributions from magnetic metals such as Fe, Co, and Ni, as well as other d-block metals, are negligible. [Fan 2019; Zhao 2014] HNO (67-70 wt%, TraceMetal™ grade, Fisher Chemical), HCl (37 wt%, 99.99% trace metals base, Millipore-Sigma), and water (Millipore-Sigma, ACS reagents for ultratrace analysis) were used for sample digestion. All samples were digested by the dilute aqua regia method. Samples were immersed in a HNO / HCl (1 M each) solution at 85°C for 6 hours. The acidic solution was filtered to remove any undissolved particles. The solution was then diluted to the appropriate concentration range using 2 wt% HNO within the calibration curve. ICP-MS was performed using a Perkin-Elmer Nexion 300 ICP-MS system.

[0217]

[0290] The boron-carbon-nitrogen ternary phase diagram in Figure 21 shows the chemical compositions (boron, carbon, and nitrogen) of different f-BCN products before heat treatment, demonstrating the wide applicability to various BCN materials via the FJH method. In Figure 21, spheres 2101 and dots 2102 represent typical compounds and experimental results of the embodiments described herein. The atomic ratios were determined by XPS results.

[0218]

[0291] All of these f-BCN samples have turbostratic structures with larger interlayer spacings, as evidenced by XRD analysis of the (002) diffraction peak, along with a broad (10) peak, shifting to lower angles. The f-BCN layer spacings are 3–6% larger than those of commercial h-BN, with f-BCN-50 having the largest interlayer spacing, approximately 6.1% larger than that of commercial h-BN. See Figure 20D; also Table X.

[0219] [Table 10]

[0220]

[0292] The f-BCN sample has a larger surface area (approximately 310 m 2 / g), which possess mesopores in addition to abundant micropores. Figure 20D. Moiré patterns can be seen from the HR-TEM image of the f-BCN sample (Figure 20E), indicating the presence of turbostratic stacking structures. The corresponding FFT pattern reflects multiple sets of diffraction spots from the

[0002] direction. Figure 20F. Atomic-scale HR-TEM image shows complex Moiré patterns and excellent in-plane crystallinity. Figure 20G. STEM images confirm misaligned edges, and elemental mapping results demonstrate the presence of B, C, and N in the f-BCN-30 sample. Figure 20H.

[0221]

[0293] To confirm the presence of substitutional carbon species in the structure and to exclude hydrocarbon contamination that resulted in false positive carbon signals, electron energy loss spectroscopy (EELS) was performed. The C–K edge spectrum was 1s-π * and 1s-σ * The presence of these peaks indicates the presence of substituted carbon atoms in the conjugated structure and excludes the possibility that the carbon signals are simply from amorphous hydrocarbon contamination [Langenhorsta 2002;McGilvery 2012].

[0222] Heteroatom-doped (substituted) reflashed graphene

[0294] In an embodiment, the present invention further relates to utilizing already synthesized flash graphene in a flash doping process. Thus, the carbon feedstock is first flashed to convert it into turbostratic flash graphene. The flash graphene is then mixed with heteroatom doping compounds before undergoing a second flash. This new method achieves higher doping rates than those achieved by previously referenced single flash doping methods. A schematic of this process is illustrated in Figures 22A-22B.

[0223] Synthesis of heteroatom-substituted reflashed graphene by FJH

[0295] The FJH system (and parameters) that can be utilized to synthesize heteroatom-substituted reflashed graphene may be based on the systems described in Tour's '642 application and Tour's '111 PCT application, with modifications as discussed below. [See also Luong 2020; Chen 2022; Deng 2022]. Parameters / declarations for heteroatom-substituted reflashed graphene may include the following: (1) Flash graphene may be converted to doped flash graphene after already being flashed once. (2) This method can be performed to various degrees with several different carbon feedstocks, as well as several different doping compounds. (3) The doping rate can generally be maximized when the weight ratio of doping compound to flash graphene is 1:4. (4) Amorphous carbon feedstocks with lower surface areas can generally have higher doping rates. (5) Organic powders with low melting points may be the most effective doping compounds in some embodiments. (6) Performing the doping flash reaction under an argon atmosphere may be necessary in some embodiments for higher doping rates. (7) Amorphous carbon feedstocks with smaller particle sizes may, in some embodiments, be less effective for initial graphene conversion but more effective for subsequent doping. (8) In some embodiments, the doping flush can be reflashed once at about 3 kJ / g and then again at about 16 kJ / g to provide the highest doping rate. (9) This re-flash method can be performed using pulse width modulated DC electrical pulses from the discharge of a capacitor bank, and can also be performed using modulated or unmodulated AC and DC current sources.

[0224]

[0296] The synthesis of heteroatom-substituted reflashed graphene uses flash graphene instead of amorphous carbon as the initial reactant, allowing for higher doping rates to be achieved. The flash graphene used for reflashing can be flash graphene synthesized from FJH, including, but not limited to, the flash graphene described above with respect to 1D carbon nanomaterials, the flash graphene described in Tour's '642 patent, and the perforated and wrinkled flash graphene described in Tour's PCT application PCT / US / 64987.

[0225]

[0297] For example, in embodiments, a desired carbon feedstock for graphene conversion is selected. Two feedstocks for graphene discovered to achieve high doping rates are metallurgical coke (MC) and bituminous activated carbon (BAC), described herein, but this may vary, including plastic-derived flash graphene, holey, wrinkled flash graphene (HWFG), or graphene obtained from any source and any method. Figure 23 illustrates a schematic diagram of a reaction vessel for both. In Figure 23, the graphite electrode 2302, copper electrode 2301, and feedstock 2304 (in quartz tube 2303) all have sufficient electrical conductivity to allow the passage of electrical current necessary for Joule heating. Graphite and copper have sufficiently higher electrical conductivity than the feedstock so that most of the heat is dissipated in the feedstock. Copper helps provide more uniform electrical contact and more effectively maintains the smaller grain size of the feedstock.

[0226]

[0298] In an exemplary process utilizing metallurgical coke, several kilograms of metallurgical coke chunks were obtained from Suncoke. The metallurgical coke was then ground and sieved to a particle size diameter of 0.84 to 1.68 mm. The coke was then placed in a fused quartz tube with an inner diameter of 16 mm and a length of approximately 10 cm, and the tube was closed at either end by two graphite electrodes. The sample was then compressed to reach 1.3 Ω. The metallurgical coke was reacted in this vessel via flash Joule heating with a batch size of 5.7 g at 7.5 kJ / g using a pulse-width modulated signal divided into three duty cycles: 10% for 1 second, 20% for 0.5 seconds, and 50% for 5 seconds. The resulting flash graphene was determined to be approximately 99% converted to turbostratic flash graphene via Raman spectroscopy.

[0227]

[0299] In an exemplary process utilizing bituminous activated carbon, bituminous activated carbon was obtained already with a particle size of approximately 1-2 mm in diameter. This was then loaded into a flushing vessel in 4.2 gram batches, compressed to 1.0 Ω, and flushed at 7.5 kJ / g using the same duty cycle pattern used for the metallurgical coke. Graphene conversion was also measured to be approximately 99%.

[0228]

[0300] Once the flash graphene was produced, it was initially in the form of granules that were too large for effective mixing, so it was placed between steel balls in a planetary ball mill for 60 minutes to reduce its size to granules less than 0.2 mm in diameter.

[0229]

[0301] Subsequently, a heteroatom compound or a combination of different compounds (for co-doping) was then mixed with flash graphene in a 1:4 weight ratio in 200 mg batches using a mortar and pestle. Boric acid was used for boron doping, melamine resin for nitrogen doping, polyphenylene sulfide for sulfur doping, and perfluorooctanoic acid for fluorine doping. These compounds were selected for testing as described herein based on their low decomposition temperatures and high doping rates compared to other tested doping compounds. However, there are no specific limitations on the dopant materials that can be used, and the dopants used in the present invention are not limited to the dopants selected for testing.

[0230]

[0302] 200 mg of this mixture was then loaded into a quartz tube approximately 4 cm long and 8 mm inside diameter. Fine copper wool was then wrapped around either end of small electrodes approximately 8 mm in diameter and 4 mm thick, making electrical contact with the feed material. Small graphite cylinders approximately 8 mm in diameter and 8 mm long were then placed on either end of the quartz tube, making electrical contact with the copper electrodes. The resulting container was placed between two electrodes attached to a flash joule heating system and compressed until a resistance of less than 5 Ω was measured. The container was then placed under an argon atmosphere.

[0231]

[0303] Flash Joule heating was then performed in two stages to maximize yield. The first pretreatment flash was performed at approximately 3.1 kJ / g, and the second primary flash was performed at approximately 15.6 kJ / g. The flash reaction was performed using a pulse-width modulated discharge with a three-step duty cycle pattern of 10% for 1 second, 20% for 0.5 seconds, and 50% for 5 seconds. The difference between this flash and the one performed in Step 1 is illustrated in Figures 24A-24B.

[0232] Characterization of heteroatom-substituted reflashed graphene

[0304] Using standard characterization tools, we verified both that the resulting product was converted to graphene and that the graphene was doped with heteroatoms. Figures 25A-25C show Raman and X-ray photoelectron spectroscopy (XPS) analyses of reflashed graphene derived from N-doped BAC. As illustrated in Figure 25A, the presence of D, G, and 2D Raman peaks, as well as the relative height of the 2D peak to that of the G peak, indicate that this sample was converted to high-quality graphene (a high 2D peak is a positive indicator of graphene). Figure 25B demonstrates the presence of TS1 and TS2 Raman peaks, further indicating that the stacking of graphene layers is indeed turbostratic (disordered). In Figure 25C, nitrogen doping in the graphene crystal lattice is demonstrated (with plots 2501-2504 for N1a, graphite, pyrrole, and pyridine, respectively), which further details the chemical bonding characteristics of the nitrogen bonds. From this XPS spectroscopic analysis, it was calculated that the percentage of N doping in this sample was about 5%, which means that 5% of the atoms present in the sample were nitrogen.

[0233]

[0305] The morphology and elemental composition of the product were further verified using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX), as shown in Figures 26A-26C, which revealed reflashed graphene derived from N-doped BAC. EDX analysis demonstrated that N atoms were uniformly distributed across the entire surface of the graphene (carbon) sample. The color fading around the sample's edges was attributed to the sample being out of focus and outside the center. Using these methods, it was established that the product, confirmed to be graphene via Raman spectroscopy, is composed primarily of C but also exhibits N atoms near the surface. This analysis, in addition to the XPS analysis, served as confirmation of the presence of nitrogen in the product.

[0234]

[0306] Figures 27A-27B demonstrate the analysis of reflashed graphene from N-doped MC. The graphene characteristics of the product were again confirmed by Raman spectroscopy (again, the high 2D peak is a positive indicator of graphene), and XPS spectroscopy in Figure 27B (with plots 2701-2703 for N1a, graphite, and pyrrole, respectively) confirmed that this sample had a particularly high doping ratio of nearly 28%.

[0235]

[0307] In tested embodiments, the results of the best doping rates achieved are summarized in Figure 28, which includes results from co-doping experiments during which several different heteroatoms are doped into the graphene crystal lattice at once. (The right portion of Figure 28 (marked "BACFG") shows the co-doping of multiple different types of heteroatoms.) In tested embodiments, the doping reaction was generally more successful with flash graphene derived from metallurgical coke than with flash graphene derived from bituminous activated carbon.

[0236] Purpose

[0308] There are a variety of applications for this process and the resulting products. The present method overcomes the difficulty of effectively achieving high doping rates well above 10% in heteroatom-doped graphene. In addition, the process is easily scalable and can be used to produce doped graphene in bulk. Additionally, the low cost of the feed materials required to produce this heteroatom-doped graphene allows this method to effectively compete with other methods of producing doped graphene.

[0237]

[0309] Further potential applications of the resulting heteroatom-substituted reflashed graphene include its use as a concrete and epoxy additive to increase mechanical strength, as well as in battery electrode materials to increase performance.

[0238]

[0310] Furthermore, the ability to dope graphene using a variety of heteroatom compounds also offers the opportunity to upcycle organic waste sources into heteroatom-substituted reflashed graphene via FJH (as discussed above).

[0239]

[0311] While embodiments of the present invention have been shown and described, modifications thereof may be made by those skilled in the art without departing from the spirit and teachings of the present invention. The described embodiments and examples provided herein are merely illustrative and are not intended to be limiting. Many variations and modifications of the invention disclosed herein are possible and are within the scope of the present invention. The scope of protection is not limited by the above description, but is limited only by the claims set forth below, which scope includes all equivalents of the subject matter of the claims.

[0240]

[0312] The disclosures of all patents, patent applications, and publications cited herein, to the extent that they provide exemplary, procedural, or other details supplementary to those set forth herein, are hereby incorporated by reference in their entireties.

[0241]

[0313] Quantities and other numerical data may be presented herein in range format. It will be understood that such range format is used merely for convenience and brevity and should be interpreted flexibly to include not only the numerical values ​​expressly recited as the limits of the range, but also all individual numerical values ​​or subranges subsumed within that range, as if each such numerical value and subrange were expressly recited. For example, a numerical range of approximately 1 to approximately 4.5 should be interpreted not only to include the explicitly recited limits of 1, approximately 4.5, but also to include individual numbers such as 2, 3, 4, etc., and subranges such as 1-3, 2-4, etc. The same principle applies to ranges reciting only a single numerical value, such as "less than approximately 4.5," which should be interpreted to include all of the recited values ​​and ranges. Furthermore, such interpretation should apply regardless of the breadth of the range or characteristic described.

[0242]

[0314] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the presently disclosed subject matter belongs. Although any methods, devices, and materials similar or equivalent to those described herein can be used in the practice or testing of the presently disclosed subject matter, representative methods, devices, and materials are described herein.

[0243]

[0315] Following long-standing patent law convention, the terms "a" and "an" mean "one or more" when used in this application, including the claims.

[0244]

[0316] Unless otherwise indicated, all numbers expressing quantities of ingredients, reaction conditions, and the like used in the specification and claims are to be understood as being modified in all instances by the term "about." Accordingly, unless indicated to the contrary, the numerical parameters set forth in the specification and appended claims are approximations that may vary depending upon the desired properties sought to be obtained by the presently disclosed subject matter.

[0245]

[0317] As used herein, the terms "about" and "substantially," when referring to a value or amount of mass, weight, time, volume, concentration, or percentage, are meant to encompass variations from the specified amount of, in some embodiments, ±20%, in some embodiments ±10%, in some embodiments ±5%, in some embodiments ±1%, in some embodiments ±0.5%, and in some embodiments ±0.1%, as variations are appropriate for practicing the disclosed methods.

[0246]

[0318] As used herein, the terms "substantially perpendicular" and "substantially parallel" include, in some embodiments, meaning a variation within ±10° of each of the perpendicular and parallel directions, in some embodiments within ±5° of each of the perpendicular and parallel directions, in some embodiments within ±1° of each of the perpendicular and parallel directions, and in some embodiments within ±0.5° of each of the perpendicular and parallel directions.

[0247]

[0319] As used herein, the term "and / or," when used in the context of a list of entities, refers to the entities being present either singly or in combination. Thus, for example, the phrase "A, B, C, and / or D" includes A, B, C, and D individually, but also any and all combinations and subcombinations of A, B, C, and D.

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Explanation of Symbols

[0249] 101 Schematic Diagram 102 SEM Image 601 Ni Nanoparticles 602 Amorphous Carbon 613 Arrow 2301 copper electrode 2302 Electrode 2303 Quartz Tube 2304 Supply Materials

Claims

1. A method comprising the step of flash-heating a mixture of materials and a catalyst to form a one-dimensional structure.

2. (a) The flash Joule heating is a process that includes applying a voltage across the mixture so that a current passes through the mixture and the one-dimensional structure is formed; (b) The voltage is applied in one or more voltage pulses; (c) The method according to claim 1, wherein the duration of each of the one or more voltage pulses is over the duration period.

3. The method according to claim 1 or 2, wherein the one-dimensional structure is a nanomaterial of graphite 1D and / or a hybrid material.

4. The method according to claim 1 or 2, further comprising the step of forming a one-dimensional structure with one or more other dimensional structures selected from the group consisting of zero-dimensional structures, two-dimensional structures, and mixtures thereof.

5. The method according to claim 4, wherein the one-dimensional structure and the one or more other-dimensional structures are joined by covalent or non-covalent bonds.

6. The method according to claim 5, wherein the one-dimensional structure and the one or more other-dimensional structures are connected to form a three-dimensional network.

7. The method according to claim 1 or 2, wherein the material is a carbon material containing a polymer.

8. The method according to claim 7, wherein the mixture is formed by loading catalyst particles onto the polymer via surface wetting.

9. The method according to claim 7, wherein the mixture is formed by loading catalyst particles into the polymer via melt mixing.

10. The method according to claim 1 or 2, wherein the material is carbon-containing waste.

11. The method according to claim 1 or 2, wherein the catalyst is selected from the group consisting of iron(II) chloride, nickel(II) chloride, cobalt(II) chloride, and ferrocene.

12. The method according to claim 1 or 2, wherein the catalyst is selected from the group consisting of any transition metal or main group metal, or complexes, salts, oxides, halides, or combinations thereof of a transition metal or main group metal.

13. The method according to claim 1 or 2, wherein the mixture further comprises a conductive carbon additive.

14. The method according to claim 13, wherein the conductive carbon additive is selected from the group consisting of graphene, flash graphene, randomly layered graphene, anthracite, carbon derived from coconut shells, biochar processed at higher temperatures, activated carbon, calcined petroleum coke, metallurgical coke, coke, shungite, carbon nanotubes, asphaltene, acetylene black, carbon black, ash, carbon fibers, and mixtures thereof.

15. The method according to claim 13 or 14, further comprising the step of separating at least a portion of the conductive carbon additive from the one-dimensional structure formed after the flash Joule heating.

16. The method according to claim 15, wherein the separation step is based on the particle size of the conductive carbon additive and the size of the formed one-dimensional structure.

17. The method according to claim 16, wherein the separation step includes sieving to separate smaller one-dimensional structures from larger-particle conductive carbon additives.

18. The method according to claim 1 or 2, wherein the yield percentage of the one-dimensional structure formed by the method is at least 65%.

19. A method comprising the step of flash-heating a mixture to form boron nitride nanotubes, wherein the mixture comprises (i) a boron-containing material, (ii) a nitrogen-containing material, and (iii) a catalyst.

20. (a) The flash Joule heating is a process that includes applying a voltage across the mixture so that an electric current passes through the mixture and the boron nitride nanotubes are formed; (b) The voltage is applied in one or more voltage pulses; (c) The method according to claim 19, wherein the duration of each of the one or more voltage pulses is over a period of duration.

21. The method according to claim 19 or 20, wherein the boron-containing material and the nitrogen-containing material are different materials.

22. The method according to claim 19 or 20, wherein the boron-containing material and the nitrogen-containing material are the same material.

23. The method according to claim 22, wherein the same material is ammonia borane.

24. The catalyst is Ni(acac) ２ and / or Fe(acac) ３ The method according to claim 19 or 20.

25. The method according to claim 19 or 20, wherein the catalyst comprises Ni and / or Fe.

26. The method according to claim 19 or 20, wherein the mixture further comprises a conductive carbon source.

27. The method according to claim 26, wherein the yield percentage of boron nitride nanotubes formed by the above method is at least 45%.

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