Methods of flash-within-flash joule heating and systems thereof

Abstract

Methods of flash-within-flash (FWF) Joule heating and the systems thereof. The FWF Joule heating process subjects outer feedstock in an outer vessel to a flash Joule heating process, whereby the flash Joule heating process upon the outer feedstock results in the conversion of inner feedstock within an inner vessel (which inner vessel is within the outer vessel) to a converted material.

Description

Attorney Docket No.: 072174-05601 METHODS OF FLASH-WITHIN-FLASH JOULE HEATING AND SYSTEMS THEREOF CROSS-REFERENCED TO RELATED PATENT APPLICATIONS

[0001] The application claims priority to U.S. Patent Appl. Serial No. 63 / 520,553, to James Mitchell Tour, et al., entitled “Methods Of Flash-Within-Flash Joule Heating And Compositions Thereof,” filed August 18, 2023, which patent application is commonly owned by the owner of the present invention and is incorporated herein in its entirety. TECHNICAL FIELD

[0002] The present invention relates to methods of flash Joule heating (FJH) and systems thereof, including, particularly, methods of flash-within-flash Joule heating and the systems thereof. GOVERNMENT INTEREST

[0003] 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. ERDC W912HZ-21-2-0050 and W912HZ-24-2-0027, awarded by the United States Engineer Research and Development Center for the United States Army Corp of Engineers. The United States government has certain rights in the invention. BACKGROUND

[0004] The next generation of synthesis protocols must meet three main criteria to afford minimal environmental impact: reduced use of solvents and water, improved energy efficiency, and scalability. [Raabe 2023; Aykol 2021]. These requirements are often hard to achieve using equilibrium states of thermodynamics since many synthetic processes require high temperatures (>600 °C) or extended reaction times ranging from hours to days. Recent non- equilibrium syntheses that use rapid thermal shock via ultrafast resistive Joule heating have surfaced as more promising methods to produce specific products, including ceramics [Wang C 2022; Deng II 2022], metastable materials [Zheng 2023; Chen II 2021], and value-addedAttorney Docket No.: 072174-05601 chemicals and materials [Luong 2020; Deng I 2022; Wyss 2022; Wyss 2023; Yao 2018; Chen 2016]. These established methods are conducted in milliseconds to minutes, thereby showing substantial reductions in energy use. However, these protocols often need to meet specific electrical conductivity requirements, thereby limiting the reagents that can be used. To bypass this limitation, the introduction of conductive additives or substrate is necessary, which results in impurities and difficulty in obtaining standalone products. Furthermore, the incorporation of volatile reagents such as chalcogens (e.g., S and Se) is difficult to realize due to the intensive heat caused by resistive heating, constraining these elemental incorporations.

[0005] A limitation of FJH is the difficulty in producing amorphous carbon as the major product (<90%) from various carbon-based feedstocks including municipal solid waste. Unlike turbostratic graphene, amorphous carbon does not exhibit crystallinity and has ubiquitous use in air and water filters, cosmetics, ink, and composites. The category of amorphous carbon encompasses materials such as (activated) charcoal, activated carbon, biochar, and combinations and mixtures thereof. Since FJH converts these carbon feedstocks into turbostratic graphene during the reaction, obtaining amorphous carbon materials and derivatives (e.g., heteroatom-doped amorphous carbon) is difficult.

[0006] Accordingly, conventional flash Joule heating (FJH) cannot generally be used to produce inorganic compounds. Instead, inorganic compounds are generally produced by methods such as chemical vapor deposition, flux growth, arc melting, hydrothermal synthesis, among others. These methods typically involve a trade-off between crystalline quality, speed of synthesis, and scalability. For example, chemical vapor deposition can produce high quality crystalline materials, but it struggles to do so at gram scale and larger in under 1 hour. Likewise, flux growth can produce high quality, gram-scale inorganic crystals, but synthesis times ranges from several hours to weeks for many compounds. Conventional flash Joule heating has been demonstrated to perform multigram-scale reactions in seconds with high crystalline quality,Attorney Docket No.: 072174-05601 though it has been, until now, significantly limited in the variety of inorganic compounds that it can be used to produce due to the carbide formation, carbon contamination and unsuitable resistivities. SUMMARY OF THE INVENTION

[0007] The present invention relates to methods of flash Joule heating and systems thereof, including, particularly, methods of flash-within-flash (FWF) Joule heating and the systems thereof.

[0008] In general, in one embodiment, the invention features a method that includes providing an inner feedstock within an inner vessel. The method further includes providing an outer feedstock within an outer vessel. The inner vessel is within the outer vessel in a flash Joule heating apparatus. The method further includes applying one or more voltage pulses, alternating current (AC), direct current (DC), or a combination thereof across the outer feedstock to subject the outer feedstock to a flash Joule heating process, whereby the flash Joule heating process upon the outer feedstock results in the conversion of the inner feedstock to a converted material.

[0009] Implementations of the invention can include one or more of the following features:

[0010] The method can be performed in a continuous process in the voltage is supplied to the outer feedstock being flash Joule heated.

[0011] The flash Joule heating process upon the outer feedstock can provide conduction heating and / or radiative heating to the inner feedstock that result in the conversion of the inner feedstock to the converted material.

[0012] The flash Joule heating process upon the outer feedstock can provide conduction heating to the inner feedstock that result in the conversion of the inner feedstock to the converted material.

[0013] The flash Joule heating process upon the outer feedstock can provide radiative heatingAttorney Docket No.: 072174-05601 to the inner feedstock that result in the conversion of the inner feedstock to the converted material.

[0014] The flash Joule heating process upon the outer feedstock can provide both conductive heating and radiative heating to the inner feedstock that result in the conversion of the inner feedstock to the converted material.

[0015] The converted materials can be a 3-dimensional material.

[0016] The converted material can be a 2-dimensional material.

[0017] The converted materials can be a 1-dimensional material.

[0018] The converted materials can be amorphous material.

[0019] The converted material can be selected from the group consisting of FeS2, CoS2, CoSxSey, CoSe, NiS2, NiSe2, Cu9S5, NbSe2, MoSe2, TiSe2, In2Se3, SnS2, SnSxSey, SnSe2, WSe2, WS2, Bi2S3, BixSySez, Bi2Se3, TiN, LaBO3, Cu2Se, Cu0.87Se, and combinations and mixtures thereof.

[0020] The converted material can include chalcogenide, metal, and / or alloys.

[0021] The reactor can be used to extract metals out of ores and minerals.

[0022] The reactor can be used to extract metals from electronic waste sources.

[0023] The converted materials can include amorphous carbon and derivates thereof.

[0024] The outer feedstock can be selected from the group consisting of graphene, flash graphene, turbostratic graphene, anthracite coal, coconut shell-derived carbon, higher temperature-treated biochar, activated charcoal, calcined petroleum coke, metallurgical coke, coke, shungite, carbon nanotubes, asphaltenes, acetylene black, carbon black, ash, carbon fiber, graphite, and combinations and mixtures thereof.

[0025] The outer feedstock can be converted to flash graphene after applying the voltage pulse across the outer feedstock to subject the outer feedstock to a flash Joule heating process.

[0026] The flash graphene can be re-used multiple times as the outer feedstock in the above-Attorney Docket No.: 072174-05601 described methods.

[0027] The method can further include removing the converted material from the inner vessel. The method can further include providing a second inner feedstock within an inner vessel. The method can further include applying one or more voltage pulses, alternating current (AC), direct current (DC), or a combination thereof across the flash graphene in the outer vessel to subject the flash graphene to a flash Joule heating process, whereby the flash Joule heating process upon the flash graphene results in the conversion of the second inner feedstock to a second converted material.

[0028] The second inner feedstock can be the same type of feedstock as the inner feedstock converted into the converted material. The second converted material can be the same type as the converted material.

[0029] The second inner feedstock can be a different type of feedstock as the inner feedstock converted into the converted material. The second converted material can be a different type from the converted material.

[0030] The step of applying the one or more voltage pulses can utilize DC voltage.

[0031] The step of applying the one or more voltage pulses can utilize pulsed DC.

[0032] The step of applying the one or more voltage pulses can utilize AC voltage.

[0033] The step of applying the one or more voltage pulses can utilize a combination of DC voltage and AC voltage.

[0034] The step of applying the one or more voltage pulses, AC, DC, or a combination thereof can include controlling the flash Joule heating process through controlled electronic modulation. The controlled electronic modulation can occur through a control selected from the group consisting of variable frequency drive (VFD), pulse width modulation (PWM), proportional–integral–derivative (PID) control, three-term control, and combinations thereof.

[0035] The controlled electronic modulation can utilize (i) DC current (ii) a uniform, non-Attorney Docket No.: 072174-05601 traveling AC current, or (iii) a combination thereof.

[0036] The method can further include applying an inner vessel current through the inner feedstock when applying the one or more voltage pulses, AC, DC, or a combination thereof across the outer feedstock.

[0037] The applying of the current through the inner feedstock can be independently controlled when applying the one or more voltage pulses, AC, DC, or a combination thereof across the outer feedstock.

[0038] A separate tube can be made of graphite foil rolled into a cylinder that can be used as the heating element that is external to the inner quartz tube.

[0039] A graphite tube can be used as both the heating and the feedstock-holding tube.

[0040] A gap or physical separation can exist between the graphite tube and the inner tube to inhibit the conductive heating of the inner tube and promote radiation as the primary heating mechanism.

[0041] The entire system can be enclosed by a quartz tube.

[0042] Inert gas can be flown through this gap to permit convective, conductive, and / or a combination thereof heating.

[0043] Reactive gas can be flown into the chamber with the feedstock to assist in chemical synthesis or decomposition.

[0044] The reactive gas can be chlorine gas.

[0045] Reactive gas can be flown into the chamber with the feedstock to assist in chemical synthesis or decomposition of ores.

[0046] The separate tube can be reused multiple times.

[0047] The separate tube can be made of graphite. (Since graphite is stable when heated electrically, it can be reused many times).

[0048] The system can be arranged in a pattern of concentric tubes, alternating between heatingAttorney Docket No.: 072174-05601 tubes and feedstock-holding tubes.

[0049] The tubes can have a cylindrical shape.

[0050] The tubes can have a non-cylindrical shape.

[0051] The non-cylindrical shape can be a half-.

[0052] In general, in another embodiment, the invention features an apparatus that includes an inner vessel operable for receiving an inner feedstock. The apparatus further includes an outer vessel operable for receiving an outer feedstock. The outer vessel is a non-conductive vessel operable for constraining the outer feedstock or a conductive vessel operable to be directly flash Joule heated. The apparatus further includes electrodes that are operable for applying a voltage pulse, AC, DC, or a combination thereof across the outer feedstock constrained within the outer vessel to subject the outer feedstock to a flash Joule heating process, wherein the flash Joule heating process upon the outer feedstock results in the conversion of the inner feedstock to a converted material.

[0053] Implementations of the invention can include one or more of the following features:

[0054] The outer vessel can be a non-conductive vessel operable for constraining the outer feedstock.

[0055] The outer vessel can be a conductive vessel operable to be directly flash Joule heated.

[0056] The apparatus is operable for performing a continuous process in which the voltage is supplied to the outer feedstock being flash Joule heated.

[0057] The converted materials can be a 3-dimensional material.

[0058] The converted material can be a 2-dimensional material.

[0059] The converted materials can be a 1-dimensional material.

[0060] The converted materials can be amorphous material.

[0061] The converted material can be selected from the group consisting of FeS2, CoS2, CoSxSey, CoSe, NiS2, NiSe2, Cu9S5, NbSe2, MoSe2, TiSe2, In2Se3, SnS2, SnSxSey, SnSe2, WSe2,Attorney Docket No.: 072174-05601 WS2, Bi2S3, BixSySez, Bi2Se3, TiN, LaBO3, Cu2Se, Cu0.87Se, and combinations and mixtures thereof.

[0062] The converted material can include chalcogenide, metal, and / or alloys.

[0063] The reactor can be used to extract metals out of ores and minerals.

[0064] The reactor can be used to extract metals from electronic waste sources.

[0065] The outer feedstock can be selected from the group consisting of graphene, flash graphene, turbostratic graphene, anthracite coal, coconut shell-derived carbon, higher temperature-treated biochar, activated charcoal, calcined petroleum coke, metallurgical coke, coke, shungite, carbon nanotubes, asphaltenes, acetylene black, carbon black, ash, carbon fiber, graphite, and combinations and mixtures thereof.

[0066] The outer feedstock can be converted to flash graphene after applying the voltage pulse, AC, DC, or a combination thereof across the outer feedstock to subject the outer feedstock to a flash Joule heating process.

[0067] The outer feedstock is not graphite.

[0068] The electrodes can be connected to a DC voltage source.

[0069] The electrodes can be connected to a pulsed DC source.

[0070] The electrodes can be connected to an AC voltage source.

[0071] The electrodes can be connected to a DC voltage source and an AC voltage source.

[0072] The apparatus can further include a controller that controls the flash Joule heating process applied by the electrodes through controlled electronic modulation. The controller can be selected from the group consisting of variable frequency drive (VFD) controllers, pulse width modulation (PWM) controllers, proportional–integral–derivative (PID) control controllers, three-term control controllers, and combinations thereof.

[0073] The controlled electronic modulation operably utilizes (i) DC current (ii) a uniform, non-traveling AC current, or (iii) a combination thereof.Attorney Docket No.: 072174-05601

[0074] The apparatus can further include inner vessel electrodes that are operable for applying an inner vessel current through the inner feedstock when applying the one or more voltage pulses, AC, DC, or a combination thereof across the outer feedstock.

[0075] The inner vessel electrodes are operable to be independently controlled when applying the one or more voltage pulses, AC, DC, or a combination thereof across the outer feedstock.

[0076] The apparatus can further include a controller that independently controls the application of the current through the inner feedstock when applying the one or more voltage pulses, AC, DC, or a combination thereof across the outer feedstock.

[0077] A separate tube can be made of graphite foil rolled into a cylinder that can be used as the heating element that is external to the inner quartz tube.

[0078] A graphite tube can be used as both the heating and the feedstock-holding tube.

[0079] A gap or physical separation can exist between the graphite tube and the inner tube to inhibit the conductive heating of the inner tube and promote radiation as the primary heating mechanism.

[0080] The entire system can be enclosed by a quartz tube.

[0081] Inert gas can be flown through this gap to permit convective, conductive, and / or a combination thereof heating.

[0082] Reactive gas can be flown into the chamber with the feedstock to assist in chemical synthesis or decomposition.

[0083] The reactive gas can be chlorine gas.

[0084] Reactive gas can be flown into the chamber with the feedstock to assist in chemical synthesis or decomposition of ores.

[0085] The separate tube can be reused multiple times.

[0086] The separate tube can be made of graphite.

[0087] The system can be arranged in a pattern of concentric tubes, alternating between heatingAttorney Docket No.: 072174-05601 tubes and feedstock-holding tubes.

[0088] The tubes can have a cylindrical shape.

[0089] The tubes can have a non-cylindrical shape.

[0090] The non-cylindrical shape can be a half-pipe.

[0091] The graphite foil can be clamped to a copper or brass tube to provide electrical contact, while also providing access for insertion of quartz tube that holds the material to be flash heated.

[0092] A graphite cylinder can be used. The graphite cylinder can have a section to be heated with a reduced outer diameter or longer length to increase the resistance in the section.

[0093] Support rods can connect the clamps to keep the structure rigid and minimize strain on the graphite heating element.

[0094] Quartz cylinders or rods can be used to define the distance between the clamps, which can withstand heat and do not undergo thermal expansion when heated to reduce strain on the graphite foil cylinder.

[0095] Metal rods and springs can be used as tension elements, mounted in an insulating sleeve to prevent electrical conduction between the clamps.

[0096] The assembly can be enclosed in an outer cylinder that is purged with inert gas or is evacuated to prevent oxidation of the electrically heated graphite tube.

[0097] The outer cylinder can be a quartz or borosilicate tube.

[0098] The outer cylinder can be a metal tube that can be pressurized.

[0099] A radiation shield can be placed around the tubular graphite heater to reflect outgoing radiation back onto this heater element, and thereby reduce the electrical energy needed to maintain the temperature.

[0100] The radiation shield can include one of more of copper, nickel, molybdenum, and aluminum.Attorney Docket No.: 072174-05601

[0101] A gold coating can be used to enhance reflectivity.

[0102] End caps can be PTFE or other insulating material that holds and seals the copper or brass tubes.

[0103] Water cooling can be added to the copper or brass tubes.

[0104] Heat from the graphite tube can be transmitted by radiation, convection, and conduction through the small gap when an inert gas is present.

[0105] The enclosure can be evacuated and heat transfer into the inner quartz tube occurs by radiation.

[0106] A small opening or slot can be made in the graphite tube to provide an observation port for the inner quartz tube and sample.

[0107] There can be no electrical connection between the graphite tube and the material inside the quartz tube to allow external heating and electrical fields to be applied independently.

[0108] In general, in another embodiment, the invention features an apparatus that includes an inner vessel operable for receiving a feedstock. The apparatus further includes an outer vessel operable to provide a protective atmosphere or vacuum for the resistive heater. The apparatus further includes a resistive heater within the outer vessel. The apparatus further includes electrodes that are operable to provide AC or DC current to the resistive heater. The apparatus further includes plugs in the inner vessel to contain the feedstock therein.

[0109] Implementations of the invention can include one or more of the following features:

[0110] The inner vessel can be a transparent inner vessel. The resistive heater can be a tubular resistive heater. The resistive heater can be concentric within the outer vessel. The electrodes can be tubular electrodes.

[0111] The inner vessel can be a fused quartz tube.

[0112] The inner vessel can be a transparent fused quartz tube.

[0113] The resistive heater can be a rolled-up graphite foil.Attorney Docket No.: 072174-05601

[0114] The resistive heater can be a graphite tube.

[0115] The resistive heater can be a graphite tube thinned in the center.

[0116] The outer vessel can be a fused quartz tube.

[0117] The outer vessel can be a fused quartz tube enclosed with PTFE endcaps and O-ring seals.

[0118] The outer vessel can be a metal tube.

[0119] The outer vessel can be a metal tube operable for withstanding pressure.

[0120] The electrodes can include a metal selected from the group consisting of copper, brass, nickel, and combinations thereof.

[0121] The electrodes can be selected from the group consisting of copper electrodes, brass electrodes, nickel electrodes, and combinations thereof.

[0122] The apparatus can further includes graphite foil clamped to the electrodes.

[0123] The apparatus can further include a rigid support structure of tubes or rods that minimizes strain on the resistive heater.

[0124] The tubes or rods can be quartz tubes or rods.

[0125] The resistive heater can include graphite foil.

[0126] The resistive heater can be a graphite tube.

[0127] The resistive heater can be electrically heated by applying one or more voltage pulses, alternating current (AC), direct current (DC), or a combination thereof.

[0128] The application one or more voltage pulses, alternating current (AC), direct current (DC), or a combination thereof can provide radiant heat transfer to the feedstock inside the inner vessel.

[0129] The plugs in the inner vessel can be conductive.

[0130] The plugs in the inner vessel can be connected to a high voltage power supply.

[0131] The plugs in the inner vessel can be connected by wires to a high voltage power supply.Attorney Docket No.: 072174-05601

[0132] The plugs in the inner tube can be porous.

[0133] The plugs in the inner tube can be porous to allow for gases to enter or exit.

[0134] The apparatus is operable for one or more voltage pulses, alternating current (AC), direct current (DC), or a combination thereof to be applied to the feedstock in the inner vessel. BRIEF DESCRIPTION OF THE DRAWINGS

[0135] FIG.1A-1D show flash-within-flash (FWF) Joule system protocols operated in the heat conduction mode in embodiments of the present invention. FIG. 1A shows a schematic description of FWF (Type 1). FIG.1B shows the current and temperature profile of a 340 V FWF reaction. FIG. 1C shows a schematic description of a multiple FWF reaction (Type 2) for allowing further (and possibly full) conversion of unreacted precursors. FIG.1D shows a schematic description of anion-exchange FWF reaction (Type 3) for bypassing unexpected (and / or undesired) side reactions.

[0136] FIG.2 shows a circuit diagram of a capacitor bank discharge system that can be used in a FWF process.

[0137] FIGS.3A-3F shows the FWF system protocols operated in the radiative heating mode. FIG. 3A shows a scheme that describes a graphite tube heater, longitudinal section, tube support of a device that allows radiative FWF heating. FIG.3B shows a scheme of a sectional view of the graphite tube heater, longitudinal section, tube support of FIG.3A. FIG.3C shows a scheme that describes a graphite tube heater, longitudinal section, tube support of a further device that allows radiative FWF heating. FIG.3D shows a scheme of a sectional view of the graphite tube heater, longitudinal section, tube support of FIG.3D. FIG.3E shows a scheme that describes the graphite tubular heater of FIG. 3C with independent electric field / current. FIG.3F shows the scheme of a rigid graphite tube that can be used in embodiments.

[0138] FIG.4 shows a scheme of an embodiment of the FWF, showing the FWF reaction can be divided conceptually between the inner and outer tubes.Attorney Docket No.: 072174-05601

[0139] FIGS. 5A-5F show internal tube temperature measurement for FWF. FIG. 5A is a schematic description of the temperature measurement for a normal FWF reaction. FIG.5B is a schematic description of the temperature measurement of skewed internal tube to decipher internal temperature during the reaction. FIG. 5C shows the infrared thermometer with an alignment laser was focused onto the sample area to read the time-dependent temperature change during the FWF reaction. FIGS. 5D-5F show the reaction dynamics during the FWF reaction.

[0140] FIGS. 6A-6D show gram scalability of FWF. FIG. 6A is a photograph of 1.11 g of WSe2powder in an analytical balance obtained from the gram-scale reaction. Scale bar, 10 cm. FIG.6B is XRD spectrum of WSe2made through a gram-scale reaction. A reference spectrum is also provided (below) in FIG.6B. FIG.6C is Se 3d XPS spectrum of WSe2powder made through a gram-scale reaction. FIG.6D is W 4f XPS spectrum of WSe2powder made through a gram-scale reaction.

[0141] FIGS. 7A-7H show diverse reactions and products from FWF. FIG. 7A is a list of representative elements used for the FWF reactions. The small subsets indicate the corresponding anion constituents used to make the inorganic compounds. FIG.7B is a list of all the final products with respect to the initial flashing voltage and corresponding energy input. All the syntheses used Type 1 reactions for FWF unless otherwise specified. FIGS.7C-7E are ADF-STEM images and EDX mapping of (C) SnS2, (D) SnSe2, and (E) Se-doped SnS2(denoted as SnSxSey), to show reagent-dependent tunability and doping (substitution) capability. FIGS. 7F-7H are ADF-STEM images and EDX mapping of semiconducting materials (F) MoSe2(n-type), (G) WSe2(p-type), and (H) α-In2Se3(n-type, ferroelectric).

[0142] FIGS. 8A-8D show selected area electron diffraction (SAED) patterns of SnS2, α- In2Se3, MoSe2, and WSe2flakes. FIG.8A shows SAED of SnS2. FIG.8B shows SAED of α- In2Se3. FIG. 8C shows SAED of MoSe2. FIG. 8D shows SAED of WSe2. All the materialsAttorney Docket No.: 072174-05601 showed a single-crystalline nature in each flake.

[0143] FIGS.9A-9B show XRD and Raman spectra for doping capability in Sn-based TMDs. FIG.9A shows XRD spectrum of SnS2, Se-doped SnS2(denoted as SnSxSey), and SnSe2. FIG. 9B shows Raman spectrum of SnS2, Se-doped SnS2(denoted as SnSxSey), and SnSe2with pictures of corresponding powders as subsets.

[0144] FIGS. 10A-10H show electrical properties characterization of FWF products. FIG. 10A shows a device schematic showing experimental FET device geometry. Schematics of crystal structure of the MoSe2, WSe2and α-In2Se3are shown in the dashed box. FIG. 10B shows cross-sectional ADF-STEM images of MoSe2, WSe2and α-In2Se3in their respective FET devices. FIGS.10C-10E show the representative transfer curves (gate-voltage (VG)–drain current (ID) characteristics under constant drain voltage (VD)) for n-type MoSe2, p-type WSe2and ferroelectric α-In2Se3under different VD(VD= 0.1 V and 1 V, respectively). The insets show the optical images of FET devices. Scale bar, 10 μm. FIGS. 10F-10G show the representative output curves (VD–IDcharacteristics under constant VG) for n-type MoSe2and p- type WSe2 FET devices from VG= −40 V to VG= 40 V, respectively. FIG. 10H shows endurance characteristics of ferroelectric In2Se3FET device for 1,000 cycles. The operation voltages are VG= −40 V (for SET) and VG= 40 V (for RESET), and read voltage is VD= 1 V.

[0145] FIGS.11A-11B shows a comparative analysis of tribological performance. FIG.11A shows time-dependent coefficient of friction (COF) change for 120,000 measurements of reference alumina, commercial MoSe2, and FWF MoSe2. Moving-average trend lines for the reference alumina, commercial MoSe2, and FWF MoSe2under 1 N are shown concurrently. FIG.11B shows force-dependent COF change for reference alumina, commercial MoSe2and FWF MoSe2.

[0146] FIGS.12A-12F are S / TEM images and SAED patterns for commercial (A-C) MoSe2and (D-F) FWF MoSe2. FIG.12A shows a TEM image of commercial MoSe2with ~20 nm ofAttorney Docket No.: 072174-05601 amorphous layer at the edge of the flake. FIG. 12B shows a TEM image of another area of commercial MoSe2with ~10 nm amorphous layer at the edge of the flake. FIG.12C shows the SAED pattern of commercial MoSe2indicating polycrystallinity and amorphous constituents. FIG.12D shows a TEM image of FWF MoSe2with little to no amorphous layer at the edge of the flake. FIG.12E shows an ADF-STEM atomic resolution image of MoSe2indicating sharp, well-defined crystalline structure at the edge of the flake. FIG. 12F shows SAED pattern of FWF MoSe2.

[0147] FIGS.13A-13D show comprehensive life cycle assessment for FWF. FIG.13A shows cumulative energy demand analysis. FIG. 13B shows global warming potential analysis. FIGS. 13C-13D show (C) cumulative water use analysis and (D) preliminary estimated product cost (techno-economic analysis), respectively of FWF compared with autoclave (Mg- assisted) and CVT syntheses for producing 100 g of MoSe2. CO2e, CO equivalent. DETAILED DESCRIPTION

[0148] The present invention relates to methods of flash Joule heating and systems thereof, including, particularly, methods of flash-within-flash (FWF) Joule heating and the systems thereof.

[0149] A general, non-equilibrium FWF Joule heating synthesis protocol has been discovered that has an ultrafast heat conduction mechanism that provides a rapid synthesis of various compounds in second. In this FWF process, a flash Joule heating reaction can be performed wherein the target feedstock is placed in a small reaction vessel that is inside a larger reaction vessel, placed among typical carbon-based flashing feedstock. This allows the inner, target feedstock to react without contamination by the outer, flashing feedstock and without any constraints on the resistivity of the target feedstock.

[0150] FWF overcomes the limitations of traditional equilibrium-based large-scale synthesis methods, enabling faster reaction rates and reduced reliance on solvents, water, and energy.Attorney Docket No.: 072174-05601 FWF additionally offers a versatile, efficient, and scalable protocol for producing a wide range of inorganic compounds with exceptional control over synthesis parameters to produce phase- selective and single-crystalline bulk powders. FWF demonstrates flexibility in materials modification through doping and gram scalability and provides for environmentally friendly access to designed inorganic materials with enormous cost savings. Moreover, diverse applications can be realized with FWF materials, such as, for example, MoSe2outperforming commercially available MoSe2in tribological performance.

[0151] FWF heating processes are further distinguished from FJH processes by two distinctive methods of heating: conductive heating and radiative heating. While FJH depends on the direct current flow into the material to induce resistive heating within the sample, FWF relies on heat transfer methods. Heat conduction generally dominates when there is a medium for heat transfer. When the FWF process takes place under ambient conditions, in pressurized systems, in direct contact with the materials being flash Joule heated, or conducted for a short period of time, the major heat transfer method is the heat conduction.

[0152] On the other hand, when the FWF process occurs under vacuum, not in direct contact with the material being flash Joule heated, or conducted for a long period, the radiative heating method dominates, as there is no medium through which heat can travel. The radiation includes infrared to ultraviolet wavelengths, depending on the temperature of the materials being flash Joule heated.

[0153] Another heating aspect could arise from exothermic or endothermic reactions within the inner vessel. The inner tube can have a higher (or lower) temperature than the outer material being flash Joule heated when the inner reaction is exothermic (or endothermic). Flash-Within-Flash Joule Heating (FWF) Process

[0154] FIG. 1A shows a schematic description of FWF utilized in an embodiment of the present invention. As shown in pre-process schematic 100, the FWF process involves using aAttorney Docket No.: 072174-05601 system with two vessels (typically quartz vessels): an outer flashing vessel 103 filled with an inexpensive conductive feedstock 105, such as metallurgical coke, and an inner, semi-closed reactor 108 that contains the target reagents 107 (the precursors). Pre-process schematic 100 shows the system can further include copper wool plugs 104 (or graphite disks) that can come in contact with the conductive feedstock 105 and electrodes 106 (graphite, copper, or any conductive refractory material).

[0155] As shown in during-process schematic 101, during the FWF process, the system is in an ambient atmosphere and flash Joule heating (FJH) is applied to the outer vessel. The FJH process is conducted through the custom-made capacitor banks discharge system. FIG. 2. [Deng II 2022]. Current 109 passes through conductive feedstock 105 in the outer vessel 103, leading to resistive Joule heating and the generation of high temperatures of ~2000 °C as measured by an infrared camera equipped with an alignment laser, FIG.1B. FIG.1B shows current profile 121 and temperature profile 122 of a 340 V FWF reaction. Dashed boxes 123- 125 indicate, respectively, 10%, 20%, and 50% duty cycle regions.

[0156] The intense heat 110 produced in the outer vessel 103’s conductive feedstock 105 then transfers to the inner vessel 108 through thermal conduction, allowing for ultrafast heating of reagents 107 in the inner tube 108. The voltage used to synthesize materials can be varied, such as in ranges from 220 V to 340 V in embodiments discussed and described herein. To minimize the risk of explosion and possible damage to the custom-built capacitor banks during the reaction, the current flow was regulated using a pulsated duty cycle. This technique evenly distributes the current flow and corresponding resistive heating across the sample during the 5- second reaction duration that was utilized. The pulsated discharge through duty cycles also allows continuous change in temperature, pressure, and volume to trigger the non-equilibrium, kinetically controlled reaction while forming specific targeted products 111 in the inner vessel 108, as shown in post-process schematic 102. [Dong 2022]. Concurrently, the conductiveAttorney Docket No.: 072174-05601 feedstock 105 outer vessel 103 (which was metallurgical coke) turns into turbostratic graphene to give additional value-added chemicals in a single reaction. The entire process can take place in just under 5 s, highlighting the ultrafast kinetics of FWF.

[0157] There is no requirement for the inner vessel to contain conductive material. By this process, for example, crystal growth of several transition metal dichalcogenides can be achieved. These target products in the inner tube are distinguished from the conductive carbon reactants in the outer tube, which again can be converted to other products, such as turbostratic flash graphene.

[0158] In embodiments, parameters for FWF Joule heating can include the following: a. The outer feedstock responsible for the Joule heating is resistive enough for current to heat the sample while being conductive enough for the current to flow through, generally 1-10 Ohm. b. The outer feedstock is in electrical contact with the outer electrodes so that current can flow through the outer tube from one side to another. c. There are no limitations on the resistivity of the target feedstock in the inner tube. d. The inner feedstock can be, but does not necessarily have to be, in electrical contact with the outer feedstock. The caps in the inner vessel can permit electrical current through the inner vessel if they are electrically conducting, as with copper or graphite or both. Or the caps in the inner vessel can restrict electrical current through the inner vessel, as with ceramic caps. e. The inner reaction vessel can be composed of fused quartz due to its chemical inertness, high thermal shock resistance, and high electrical resistivity. (In the examples herein, a fused quartz inner reaction vessel was utilized). Alternatively, or additionally, the inner reaction vessel could be, or couldAttorney Docket No.: 072174-05601 include, ceramic or concrete. f. This method allows for the formation of products that are not normally formed or produced in high yields by conventional flash Joule heating. g. The chemical products of these reactions are generally oxidative products. h. The method can be used for synthesizing single crystalline material comparable in quality to crystals produced via chemical vapor deposition. i. When a conductive carbon feedstock is used in the outer vessel, this carbon is converted into high quality turbostratic flash graphene and it can be re- used many times as the outer vessel’s feedstock contents. j. A mass ratio of around 8:1 of outer feedstock-to-inner reactant can be used for these reactions. k. The reaction energy input per gram of inner feedstock can be around 48 kJ / g to 90 kJ / g. l. These reactions can be done under vacuum, or under ambient atmospheric conditions or done under other gases inside the inner or inner plus outer reaction vessels.

[0159] The set-up for the FWF process is complementary to the systems and methods for the synthesis of graphene by flash Joule heating disclosed and described in Tour ’967 PCT Application. The FWF method has been used with a pulse-width-modulated DC electrical pulse the discharge of a capacitor bank and can also be done with unmodulated DC, AC pulses, or a combination thereof. These reactions have been scaled up to 1 gram of target product within the inner vessel and can be envisions to scale far beyond that, from kilograms to tens or hundreds of kilograms.

[0160] FIGS.3A-3F show the FWF system protocols operated in the radiative heating mode. The radiative heating is dominant when the FWF process occurs under vacuum, not in directAttorney Docket No.: 072174-05601 contact with the material being flash Joule heated, or conducted for a long period of time. For these reaction environments, the radiative heating method dominates, as there is no medium through which heat can travel. The radiation includes infrared to ultraviolet wavelengths, depending on the temperature of the materials being flash Joule heated.

[0161] FIG. 3A shows the scheme that describes a graphite tube heater 300 (longitudinal section, tube support) of a device that allows radiative FWF heating. The viewpoint of the graphite tube heater 300 is longitudinal. The heating element is rolled graphite foil (graphite double layer 312 and graphite single layer 313). The holder that is responsible for keeping the apparatus rigid is composed of three quartz tube (covered with Cu foil), namely outer quartz tube 303 (which can have a 63 mm ID), quartz tube sample holder 315 (which can have an 8 mm ID and 12 mm OD), and a third quartz tube (not shown). Other features of graphite tube heater 300 include water cooling 301, end plugs 302 (such as PTFE end plugs), nuts 304, springs 305, bushings 306 (such as ceramic bushings), shaft clamps 307, quartz tube support spacers 308 (which can be covered with Cu foil), threaded / tension rods 309 (such as 6-32 threaded / tension rod), radiation reflectors 310, shims 311 (such as Cu shim), tubes 314 (such as Cu or brass tubes with 5 / 8” OD), N2316, viewpoint in reflector 317, O-rings 318, and vacuum 319. Springs 305 can maintain constant compression, shaft clamps 307 are two-part shaft clamps that had ¾” ID and 2” OD, the graphite sheets can 0.005” thick and narrowed in the middle to provide a single tubular layer. FIG.3A also does not show the wire connections that would be at the copper tube ends of graphite tube heater 300.

[0162] FIG.3B shows the scheme of a sectional view of graphite tube heater 300, which allows the evaporation and deposition of materials onto the desired substrate of choice (metal or insulating materials). The viewpoint of graphite tube heater 300 is sectional and shows further features of split sleeve 325 (such as split Cu sleeve), deposit plate 329 (such as deposit Al or CU plate), and evaporating plate 330 (such as evaporating carbon / graphite plate). Clamps andAttorney Docket No.: 072174-05601 electrodes are shown dashed in graphite tube heater 300.

[0163] To change the length of graphite tube heater 300, tubular spacers 308 and threaded / tension rods 309 would need to be cut to the appropriate lengths.

[0164] FIG. 3C shows the scheme of a graphite tube heater 340 (longitudinal section, tube support) that describes the device that allows radiative FWF heating. Similar to FIG.3A, the viewpoint of the graphite tube heater 340 is longitudinal. The heating element rolled graphite foil (graphite double layer 312 and graphite single layer 313) with four rods 343 (such as quartz rods 4 mm) as the support holders (two of which are shown in FIG.3C). Features of graphite tube heater 340 are similar to graphite tube heater 300 with O-ring retainer 341 also shown.

[0165] FIG.3D shows the scheme of a sectional view of graphite tube heater 340 that allows the evaporation and deposition of materials onto the desired substrate of choice (metal or insulating materials) with four rods 343 as support holders. The viewpoint of graphite tube heater 340 is sectional. Also shown is wrap and spacer 351 (such as Cu foil wrap and spacer).

[0166] Graphite tube heater 340 provides for an easier adjustment of length; however, it can be more fragile.

[0167] Graphite tube heaters 300 and 340 have radiation reflectors 310 to reduce losses from outgoing radiation.

[0168] In embodiments, the inner feedstock is non-conductive and conductive material cannot be easily added to the inner feedstock (as this would affect the resultant product). In such instance, the heat comes from the FJH process occurring in the outer vessel. In such circumstances, the plugs of the inner vessel do not need to be conductive; for example, the plugs of the inner vessel can be ceramic. However, there are embodiments in which it would be advantageous for the inner vessel to have plugs that are conductive electrodes on each end. For instance, the inner feedstock is itself conductive or becomes conductive during the FJH process. In such circumstances, the embodiments would have a current passing through theAttorney Docket No.: 072174-05601 inner feedstock in the inner vessel, which can lower the activation energy of the desired thermal process occurring within the inner vessel.

[0169] FIG.3E shows the scheme of graphite tube heater 360, which is graphite tube heater 340 having independent electric field / current to provide current passing through the inner feedstock in the inner vessel during the FJH process. As shown in FIG.3E, a resistive or non- conducting sample 363 is placed inside the inner quartz tube. Electrodes 369 connected to wires 361 are placed on each end of sample 370. Wires 361 are resistant to heat (such as nickel, tungsten, or carbon rods). Wires 361 are insulated outside the quartz tube. Wires 361 are connected to a high voltage power supply, AC or DC 365. Wires 368 that provide the high current needed to heat the tubular graphite heater are clamped with a cable clamp 367 onto the copper (or brass) tube 314. Wires 368 are connected to a welding power supply or a power supply that can provide high current 366. The end of the quartz sample holding tube can be sealed with plugs / fittings 364 (which fittings can allow for gas entry and collection). Tubular graphite radiative heater 360 can be operated separately from the HV power supply 365. This allows fully independent control for heating the sample, and the electrical field or current applied directly to the sample 363.

[0170] By providing fittings that can allow for gas entry and collection, a gas, such as chlorine, can be introduced into the sample 363 in the inner tube. Thus, graphite tube heater 360 can be used to extract metals out of ores and minerals, such as extraction of lithium from spodumene, by Joule heating or electrothermal chlorination. [Tour ’556 Application].

[0171] Graphite tube heater 360 can also be used, for example, to extract / remove (a) metals from waste, such as electronic waste, such as printed circuit boards, or industrial waste, such as coal fly ash or bauxite residue (such metals can be metals that are essential for the electronics industry, such as rare earth elements, gallium, tantalum, indium or germanium); (b) metals from waste batteries, such as lithium, cobalt, nickel or manganese; and (c) iron from bauxiteAttorney Docket No.: 072174-05601 residue so that the remaining aluminum can be further purified.

[0172] FIG.3F shows the scheme with a rigid graphite tube 370 as the heating element with the thinner graphite serving as the heating zone due to the resistance difference. Rigid graphite 370 is machined to be thinner in the center. For example, for a rigid graphite tube 380 having a longitudinal length 375 of 3.8” (with an ID 372 of 0.5” and an OD 374 of 1”), a middle section length 373 can be 1.4” with an annulus length 372 of about 0.03” (i.e., the outer diameter of the middle section is about 0.53”). Such rigid graphite tube 370 will have a higher resistance in the middle section, which is where the heating will occur. Rigid graphite tube 370 can be used in [lace of the rolled graphite foil in graphite tube heaters 300, 340, and 360. Larger shaft clamps can also be used to accommodate the larger end diameter.

[0173] A workflow of the flash Joule heating process for a representative FWF reaction is shown in FIG.4 and is further summarized as follows: a. In step 401, the reactants are mixed and measured. For instance, target reactant feedstock was mixed in a mortar and pestle with the desired weight ratio. The total mass of this mixture was approximately 500 mg. b. In step 402, the reactants are filled in the inner vessel and cap. For instance, the reactant feedstock mixture was placed in a small quartz tube. The tube was capped at both ends with an inert material. i. The quartz tube was generally 4 cm long with an inner diameter of 8 mm and an outer diameter of 10 mm. Thus, the width of the walls of the tube was only 1 mm. The caps were typically made of a cylinder of graphite, oftentimes in contact with copper thread rolled into a cylinder, referred to as a spacer. The copper thread may extend out of the tube better electrical contact in the inner sample was desired. The caps can also be made of insulating ceramic material.Attorney Docket No.: 072174-05601 c. In step 403, the conductive feedstock is measured. For instance, a carbon feedstock was selected such that the resistance across the main reaction vessel was 1-10 Ω. Small chunks of metallurgical coke, measured out to 4-5 grams (mostly 5 grams) was used for almost all of the representatively synthesis discussed herein unless otherwise specified). Again, metallurgical coke is a common feedstock for FWF. i. In such testing, the metallurgical coke used was obtained from SunCoke. It was then ground and sieved between 0.30 and 0.84 mm in size. Note that this was finer than the metallurgical coke used for conventional flash Joule heating when making graphene. d. In step 404, the outer tube is filled with the inner tube (with the reactants) and the conductive feedstock and capped. For instance, a quartz tube was selected and capped at one end with a graphite electrode. A copper spacer was often placed on the inside of the graphite electrode. The outer tube was filled with about 1 / 3 of the selected metallurgical coke. The filled inner reaction tube was then placed inside the outer tube on top of the conductive feedstock (metallurgical coke). The rest of the metallurgical was then poured around the inner tube so that metallurgical coke surrounded the inner tube on all sides. The outer tube was then capped with a second graphite electrode and an optional copper spacer. The tube was then compressed longitudinally to improve electrical contact. i. The outer tube generally had a length of 10 cm with an inner diameter of 16 mm and an outer diameter of 20 mm. The inner tube was typically in the exact center of the outer tube. The resistance of these nested tubes was generally around 2-5 Ω when measured across the twoAttorney Docket No.: 072174-05601 outer graphite electrodes. e. In step 405, the FWF process is performed. For instance, DC flash Joule heating was then performed on the nested tubes. The current flowed from one of the outer graphite electrodes, through the metallurgical coke in the outer tube, to the other graphite electrode. For this size of reaction, energy from 24-45 kJ was typically used. The flash was performed using a pulse width modulated DC signal with a 3-step duty cycle pattern of 10% for 1 s, 20% for 0.5 s, and 50% for 5 s. f. In step 406, the target produced is removed from the inner tube, and in step 407, the products are removed from the outer tube. Internal Tube Temperature and Reaction Dynamics

[0174] The internal tube temperature measurement has import in understanding the synthesis environment and dynamics, i.e., the synthesis-temperature-composition relationship can be utilized to further optimize the FWF process. The measurement of the internal tube temperature was attempted by moving the inner tube to the surface of the outer tube, prior to performing the model FWF reaction of converting tin(II) chloride dihydrate salt (SnCl2·2H2O) and sulfur into tin disulfide. FIGS. 5A-5F. The configuration shown in FIG. 5A allows taking the temperature of the outer tube and was described above (FIG.1B). The configuration shown in FIG. 5B allows the infrared thermometer equipped with an alignment laser to measure the internal tube temperature during the FWF process. (For both temperature measurements of FIGS.5A-5B, the laser-assisted thermometer is located 10 cm above the sample. The current flow could be different between the two configurations as the resistance might differ by packing of the metallurgical coke for the right configuration when compared to the left configuration. Yet, the total energy input remains constant). See also FIG. 5C. The samples in both configurations exhibited similar resistance of 1.5 Ω to have a good comparison between theAttorney Docket No.: 072174-05601 modified and normal FWF processes. The internal tube exhibited a much higher maximum temperature (~2550 °C) than the outer tube (~2000 °C). This unexpected result led to an investigation as what other heat sources were contributing to higher internal tube temperature.

[0175] To be precise in describing the internal tube temperature, total heatwas as described as a function of three critical heating sources: Stefan-Boltzmann radiative heating (Erad), thermal conduction heating from external FJH reaction (ETCH), and heat of reaction (EΔH). Equations (1)-(4) with parameters below were used for calculating the heat source that contributed to the internal tube temperature.where A = 0.003 m2; e = 0.7; σ = 5.67×10-8W / m2∙K4; k = 1.4 W / m∙K (thermal conductivity of quartz at 25 °C. ^^^^ ^^^^ = ^^^^2^^^^2∗ ^^^^ ^^^^2(2) where c2= 0.4 J / g∙K; m2– 0002 kg.where P chosen so that the integral of^^^^ ^^^^ over time is 1, 2, 3, 5, or 10 kJ; to= 1.5 s; c = s.

[0176] It was calculated that the radiative heating contribution would be minimal due to the short reaction time, which suggested that the heat of reaction (EΔH) would be the major contributor in making the internal tube temperature higher than the external tube. The exact measurement of ΔH was not possible since enthalpy is a state function and can only be measured when the reaction is in equilibrium. Yet, the total amount of heat released and the heat release rate during the reaction was inferred by calculating the enthalpy of the reaction at the given temperature and measuring the time-dependent internal tube temperature change,Attorney Docket No.: 072174-05601 respectively, for the reaction of interest. For example, the enthalpy of reaction for synthesizing SnS2at 2000 °C is approximately ~-410 kJ / mol. Since the total amount of SnCl2·2H2O that was used for this reaction was 1.0 g, the maximum heat that the inner reactants can release was 1.8 kJ. The time required for this reaction to go to completion can be inferred when the heating ceases. As the heat release ceased after 0.4 s into the FWF process, the heat release rate for this reaction was calculated to be 4.5 kJ·s-1. Utilizing Equations (1)-(4), by solving the differential equation, the simulated temperature profiles described the internal tube temperature. As shown, when the reaction heat release is 2 kJ, the temperature profile is similar (~2500 °C) to the observed temperature of ~2550 °C. FIG.5B. This result indicated that the heat released during the reaction significantly affected the outcome and varied across different FWF reactions conducted as discussed and described herein. Therefore, careful consideration of the specific reaction of interest was required to accurately describe the internal tube temperature. FWF Reaction Types

[0177] The FWF process can be further fine-tuned in other ways. For instance, by adapting different reaction designs, certain issues, such as slow rates and side reactions, can be mitigated, thereby producing materials that have been difficult to prepare by other methods. One type, which is referred herein as the “Type 1 reaction,” is shown in the schematics shown in FIG. 1A, as discussed above.

[0178] Another type, which is referred herein as the “Type 2 reaction” is shown in FIG. 1C includes flashing 2 to 5 times in succession, addressing the issue of partial conversion. FIG. 1C shows pre-process schematic 131 with target reagents 133 (the precursors) and the post- process schematic 132 with targets products 135 after 2-5 times sequential reaction 134. For example, the initial attempt for converting tungstic acid (WO3·H2O) to WS2did not result in full conversion, as shown by the presence of unreacted precursors in the XRD analysis. ThisAttorney Docket No.: 072174-05601 was believed to be attributed to the slow reaction rate. However, upon performing sequential FWF reactions, a near full conversion was achieved. XRD data illustrated that the signal of the starting WO3decreased with each subsequent reaction, suggesting nearly complete conversion of WO3to WS2over three FWF reaction cycles.

[0179] Another type, which is referred herein as the “Type 3 reaction” is shown in FIG. 1D that is an anion-exchange reaction, which can also address reactions that pose difficulties due to unexpected side reactions. FIG.1D shows pre-process schematic 141 with target reagents 143 (the precursors, which are metal precursors with SeS2) and the post-process schematic 142 with targets products 145 (anion exchange product) after the anion-exchange reaction 144 (facilitated with S or Se). For example, the side reaction of Bi(NO3)3·5H2O with Se leads to the evolution of a brown gas (all reactions were conducted in a well-ventilated fume hood). After performing FWF with these solid precursors, the resultant product was a mixture of BiSeO2and BiSeO5, indicating that the gas evolution was due to an unexpected oxidative reaction. This unwanted oxidation reaction was successfully bypassed by using the Type 3 reaction. Bi2Se3was synthesized using Bi(NO3)3·5H2O and SeS2, which initially yielded Bi2SxSey. This intermediate was then treated with Se to facilitate anion-exchange reactions. Similarly, by changing the added chalcogen to S, Bi2S3was afforded. The X-ray diffraction (XRD) analysis indicates that the full conversion occurred to produce either pure Bi2S3or pure Bi2Se3, as desired. Representative Synthesis Methods

[0180] All reagents used in these representative synthesis methods were used as received from the manufacturers unless otherwise specified. All reactions were conducted using the Type 1 reaction unless otherwise specified. SnS2

[0181] 0.25 g of SnCl2∙2H2O (Alfa Aesar, Reagent Grade) was ground with 0.25 g of sulfurAttorney Docket No.: 072174-05601(Millipore-Sigma) using a mortar and pestle. The resultant powder wasplaced inside the 8 mmquartz tube with graphite spacer and extruding copper wires at each end of the tube. The tube was then placed inside the 15 mm quartz tube, which was subsequently filled with 5.0 g of metallurgical coke. These tubes were flash-joule-heated at 340 V. The resultant powder was collected without further purification or washing. SnSxSey

[0182] 0.25 g of SnCl2∙2H2O was ground with 0.48 g of selenium sulfide using a mortar andpestle. The resultantpowder was placed inside the 8 mm quartz tube with graphite spacer andextruding copper wires at each end of the tube. This tube was then placed inside the 15 mm quartz tube, which was subsequently filled with 5.0 g of metallurgical coke. These tubes were flash-joule-heated at 340 V. The resultant powder was collected without further purification or washing. SnSe2

[0183] 0.25 g of SnCl2∙2H2O was ground with 0.26 g of selenium using a mortar and pestle.The resultant powderwas placed inside the 8 mm quartz tube with graphite spacer andextruding copper wires at each end of the tube. This tube was then placed inside the 15 mm quartz tube, which was subsequently filled with 5.0 g of metallurgical coke. These tubes were flash-joule-heated at 340 V. The resultant powder was collected without further purification or washing. SnSe2-gram scale

[0184] 1.0 g of SnCl2∙2H2O was ground with 1.05 g of sulfur using a mortar and pestle. Theresultant powder wasplaced inside the 8 mm quartz tube with graphite spacer and extrudingcopper wires at each end of the tube. This tube was then placed inside the 15 mm quartz tube, which was subsequently filled with 5.0 g of metallurgical coke. These tubes were flash-joule-heated at 340 V. The resultant powder was collected without further purificationAttorney Docket No.: 072174-05601 or washing. Bi2S3-Type 1

[0185] 0.25 g of Bi(NO3)3∙5H2O (Millipore-Sigma) was ground with 1.0 g of sulfur using amortar and pestle. The resultant powderwas placed inside the 8 mm quartz tube with graphitespacer and extruding copper wires at each end of the tube. This tube was then placed inside the 15 mm quartz tube, which was subsequently filled with 5.0 g of metallurgical coke. These tubes were flash-joule-heated at 300 V. The resultant powder was collected without further purification or washing. It should be noted that the material synthesis can be done both through a direct flash (Type 1) or anion-exchange flash (Type 3). BixSySez

[0186] 0.25 g of Bi(NO3)3∙5H2O was ground with 0.25 g of selenium sulfide (Millipore-Sigma)using a mortar and pestle. The resultantpowder was placed inside the 8 mm quartz tube withgraphite spacer and extruding copper wires at each end of the tube. This tube was then placed inside the 15 mm quartz tube, which is subsequently filled with 5.0 g of metallurgical coke. These tubes were flash-joule-heated at 340 V. The resultant powder was collected without further purification or washing. Bi2S3-anion exchange route (Type 3)

[0187] 0.25 g of as-prepared Bi2SxSeywas mixed with 1.0 g of S using a mortar and pestle. The resultant powder was placed inside the 8 mm quartz tube with graphite spacer and extruding copper wires at each end of the tube. This tube was then placed inside the 15 mm quartz tube, which was subsequently filled with 5.0 g of metallurgical coke. These tubes were flash-Joule-heated at 340 V. The resultant powder was collected without further purification or washing. Bi2Se3-anion exchange route (Type 3)

[0188] Bi(NO3)3∙5H2O (Millipore-Sigma) immediately forms brown gas upon mixture with SeAttorney Docket No.: 072174-05601 (Millipore-Sigma). Thus, the anion-exchange route was applied rather than the direct synthesis route for Bi2Se3.FIG.1D.0.25 g of as-prepared Bi2SxSeywas mixed with 1.0 g of Se using a mortar and pestle. The resultant powder was placed inside the 8 mm quartz tube with graphite spacer and extruding copper wires at each end of the tube. This tube was then placed inside the 15 mm quartz tube, which was subsequently filled with 5.0 g of metallurgical coke. These tubes were flash-Joule-heated at 300 V. The resultant powder was collected without further purification or washing. NiS2

[0189] 0.25 g of Ni metal powder (Millipore-Sigma, <150 µm particle size) was ground with 1.0 g of sulfur using a mortar and pestle. The resultant powder was placed inside the 8 mm quartz tube with graphite spacer and extruding copper wires at each end of the tube. This tube was then placed inside the 15 mm quartz tube, which was subsequently filled with 5.0 g of metallurgical coke. These tubes were flash-Joule-heated at 220 V. The resultant powder was collected without further purification or washing. A minute amount of NiS was detected in the XRD spectrum. NiSe2

[0190] 0.25 g of Ni metal powder (was ground with 1.0 g of Se using a mortar and pestle. The resultant powder was placed inside the 8 mm quartz tube with graphite spacer and extruding copper wires at each end of the tube. This tube was then placed inside the 15 mm quartz tube, which was subsequently filled with 5.0 g of metallurgical coke. These tubes were flash-Joule- heated at 340 V. The resultant powder was collected without further purification or washing. CoS2

[0191] 0.25 g of Co(II,III) oxide (Millipore-Sigma, <50 nm particle size) was ground with 1.0 g of sulfur using a mortar and pestle. The resultant powder was placed inside the 8 mm quartz tube with graphite spacer and extruding copper wires at each end of the tube. This tube wasAttorney Docket No.: 072174-05601 then placed inside the 15 mm quartz tube, which was subsequently filled with 5.0 g of metallurgical coke. These tubes were flash-joule-heated at 340 V. The resultant powder was collected without further purification or washing. CoSxSey

[0192] 0.25 g of Co(II,III) oxide was ground with 1.0 g of selenium sulfide using a mortar and pestle. The resultant powder was placed inside the 8 mm quartz tube with graphite spacer and extruding copper wires at each end of the tube. This tube was then placed inside the 15 mm quartz tube, which was subsequently filled with 5.0 g of metallurgical coke. These tubes were flash-joule-heated at 340 V. The resultant powder was collected without further purification or washing. CoSe

[0193] 0.25 g of Co powder (Millipore-Sigma, -100 mesh) was ground with 1.0 g of selenium using a mortar and pestle. The resultant powder was placed inside the 8 mm quartz tube with graphite spacer and extruding copper wires at each end of the tube. This tube was then placed inside the 15 mm quartz tube, which is subsequently filled with 5.0 g of metallurgical coke. These tubes were flash-joule-heated at 300 V. The resultant powder was collected without further purification or washing. MoSe2

[0194] 0.25 g of Mo metal powder (Alfa Aesar, APS 3-7 micron) was ground with 1.0 g of selenium using a mortar and pestle. The resultant powder was placed inside the 8 mm quartz tube with graphite spacer and extruding copper wires at each end of the tube. This tube was then placed inside the 15 mm quartz tube, which was subsequently filled with 5.0 g of metallurgical coke. These tubes were flash-joule-heated at 300 V. The resultant powder was collected without further purification or washing.Attorney Docket No.: 072174-05601 WSe2

[0195] 0.25 g of W metal powder (Alfa Aesar, APS 1-5 micron) was ground with 1.0 g of selenium using a mortar and pestle. The resultant powder was placed inside the 8 mm quartz tube with graphite spacer and extruding copper wires at each end of the tube. This tube was then placed inside the 15 mm quartz tube, which was subsequently filled with 5.0 g of metallurgical coke. These tubes were flash-joule-heated at 300 V. The resultant powder was collected without further purification or washing. WSe2-gram scale

[0196] 1.0 g of W metal powder was ground with 1.3 g of Se using a mortar and pestle. The resultant powder was placed inside the 8 mm quartz tube with graphite spacer and extruding copper wires at each end of the tube. This tube was then placed inside the 15 mm quartz tube, which was subsequently filled with 5.0 g of metallurgical coke. These tubes were flash-Joule- heated at 340 V. Due to the rapid volume expansion and outgassing of Se during the reaction, achieving 100% recovery of powder was not possible. The remnant powder inside the inner tube was collected without further purification or washing. The collected powder was weighted; the recovery rate was 59% where the conversion rate was ~100%. See FIGS.5A-5D. NbSe2

[0197] 0.25 g of Nb metal powder (Thermo Scientific, -325 mesh) was ground with 0.67 g ofselenium using a mortar and pestle. For Nb, the molarratio between Nb and Se has import sinceNb further reacts with Se to produce Nb2Se9. The resultant powderwas placed inside the 8 mmquartz tube with graphite spacer and extruding copper wires at each end of the tube. This tube was then placed inside the 15 mm quartz tube, which was subsequently filled with 5.0 g of metallurgical coke. These tubes were flash-joule-heated at 300 V. The resultant powder was collected without further purification or washing. A small amount of unreacted Nb was detected in the XRD spectrum.Attorney Docket No.: 072174-05601 FeS2

[0198] 0.25 g of Fe2O3∙xH2O (Millipore-Sigma, catalyst grade, 30-50 mesh) was ground with1.0 g of sulfur using a mortar and pestle. The resultant powder wasplaced inside the 8 mmquartz tube with graphite spacer and extruding copper wires at each end of the tube. This tube was then placed inside the 15 mm quartz tube, which was subsequently filled with 5.0 g of metallurgical coke. These tubes were flash-joule-heated at 220 V. The resultant powder was collected without further purification or washing. The resultant powder XPS indicated that a significant oxygen concentration was detected, suggesting that further modification such as Type 2 reaction may be required to prepare cleaner material. α-In2Se3(alpha-phase In2Se3)

[0199] 0.42 g of In metal tear-drop shot was mixed with 0.84 g of Se. The resultant mixture was placed inside the 8 mm quartz tube with graphite spacer and extruding copper wires at each end of the tube. This tube was then placed inside the 15 mm quartz tube, which was subsequently filled with 5.0 g of metallurgical coke. The tubes were flash-Joule-heated at 300 V. The resultant powder was collected without further purification or washing. TiSe2

[0200] 0.25 g of Ti metal powder (Johnson Matthey Catalog Company, -325 mesh) was ground with 1.0 g of Se using a mortar and pestle. The resultant powder was placed inside the 8 mm quartz tube with graphite spacer and extruding copper wires at each end of the tube. This tube was then placed inside the 15 mm quartz tube, which was subsequently filled with 5.0 g of metallurgical coke. These tubes were flash-Joule-heated at 300 V. The resultant powder was collected without further purification or washing. Cu0.87Se

[0201] 0.25 g of Cu metal powder was ground with 1.0 g of selenium using a mortar and pestle. The resultant powder was placed inside the 8 mm quartz tube with graphite spacer andAttorney Docket No.: 072174-05601 extruding copper wires at each end of the tube. This tube was then placed inside the 15 mm quartz tube, which was subsequently filled with 5.0 g of metallurgical coke. These tubes were flash-joule-heated at 300 V. The resultant powder was collected without further purification or washing. Cu9S5

[0202] 0.25 g of Cu metal powder was ground with 1.0 g of sulfur using a mortar and pestle. The resultant powder was placed inside the 8 mm quartz tube with graphite spacer and extruding copper wires at each end of the tube. This tube was then placed inside the 15 mm quartz tube, which was subsequently filled with 5.0 g of metallurgical coke. These tubes were flash-joule-heated at 300 V. The resultant powder was collected without further purification or washing. Cu2Se-byproduct

[0203] The reaction of flash-within-flash results in outgassing of selenium gas to the outer tube for the reaction that was conducted with more than 1 g of selenium powder inside the inner tube. This high flux of outgassing caused the copper wool (acting as the spacer) to react with the selenium gas. The resultant crystal was grinded, and powder was collected without further purification or washing. TiN

[0204] 0.25 g of Ti metal powder (Johnson Matthey Catalog Company, -325 mesh) was ground with 1.0 g of selenium using a mortar and pestle. The resultant powder was placed inside the 8 mm quartz tube with graphite spacer and extruding copper wires at each end of the tube. This tube was then placed inside the 15 mm quartz tube, which was subsequently filled with 5.0 g of metallurgical coke. These tubes were flash-joule-heated at 340 V. The resultant powder was collected without further purification or washing.Attorney Docket No.: 072174-05601 LaBO3

[0205] 0.25 g of La(NO3)3·6H2O powder (Millipore-Sigma) was ground with 0.5 g ofamorphous boron using a mortar and pestle. Theresultant powder was placed inside the 8mm quartz tube with graphite spacer and extruding copper wires at each end of the tube. This tube was then placed inside the 15 mm quartz tube, which was subsequently filled with 5.0 g of metallurgical coke. These tubes were flash-joule-heated at 340 V. The resultant powder was collected without further purification or washing. WS2*-multiple flashes (Type 2)

[0206] 0.25 g of WO3·H2O (Millipore-Sigma) was mixed with 1.0 g of S using a mortar and pestle. The resultant powder was placed inside the 8 mm quartz tube with graphite spacer and extruding copper wires at each end of the tube. This tube was then placed inside the 15 mm quartz tube, which was subsequently filled with 5.0 g of metallurgical coke. These tubes were flash-Joule-heated at 340 V. Due to the incomplete conversion and significant remnant of initial precursor, the reaction was conducted two more times with the as-synthesized powder and 1.0 g of sulfur (three in total) to convert initial tungstic acid to WS2. A minute amount of tungstic acid was observed. Product and Doping / Substitution Capability

[0207] The FWF method can be used for the general synthesis of various compounds. As discussed above, by controlling the voltages and reagents alone, 10 TMDs, 3 Group-XIV dichalcogenides, and 9 non-TMD materials have been prepared as representative examples. FIG.7A; TABLE I.Attorney Docket No.: 072174-05601 TABLE I Final Products Obtained From FWF Reactions Distinguished By Transition Metal Dichalcogenides (TMD) And Non-TMD Materials

[0208] XRD, XPS and / or (scanning) transmission electron microscopy (S / TEM) characterizations indicate successful synthesis, highlighting the consistent production of desired products. Diverse solid-state reagents can be employed including metal powders (e.g., Ni, Mo, W), metal chlorides (e.g., SnCl2·2H2O), metal oxides (e.g., cobalt(II, III) oxide, iron oxide hydrate), metal nitrates (e.g., Bi(NO3)3·5H2O), and hydrated salts as the precursors. The voltage for each reaction was optimized to produce the desired final product. FIG. 7B. The initial input voltage was directly related to the input energy, i.e., the total amount of energy delivered to the reaction can be calculated by using the below equation: 1 ^^^^ ^^^^ ^^^^ ^^^^ ^^^^ ^^^^ ^^^^ ^^^^ ^^^^ ^^^^ ^^^^ ^^^^ ^^^^ =^^^^ 2^^^^ ^^^^2 ^^^^^^^^ ^^^^ ^^^^ ^^^^ ^^^^ ^^^^ ^^^^ ^^^^ ^^^^ ^^^^ ^^^^ ^^^^ ^^^^ ^^^^ ^^^^ ^^^^ ^^^^ ^^^^(5) where C is the capacitance (624 mF), and V is the flashing voltage. For example, when flashing at 340 V with 5 g of metcoke, the total amount of energy delivered is ~7.2 kJ·g-1. Since the current does not flow through the inner tube, the inner tube mass contribution is negligible.

[0209] The corresponding energy in kJ per gram of metallurgical coke is also denoted. The internal tube temperature, however, should be calculated and measured to describe the total heat released and heat release rate, respectively, similarly to our method described above. This versatile synthesis technique overcomes not only the conductivity requirements of carbothermic, thermal shock methods including FJH, but also limitations of other synthesis protocols such as hydrothermal synthesis where solubility and type of initial precursors playAttorney Docket No.: 072174-05601 critical roles in forming the product of interest. [Joo 2011]. Even though most of the compounds synthesized in this experiment focused on the sulfides, selenides, and layered materials [Du 2020; Feng 2022], the formation of titanium nitride (TiN) and lanthanum borate (LaBO3) was demonstrated suggesting that FWF could serve as a general method for synthesizing a wide variety of inorganic compounds.

[0210] Doping (substitution) of various compounds using FWF is also possible by simply changing the initial precursor. Three different chalcogen-based reagents, S, SeS2, and Se, were used as the corresponding anions in the Sn-based system to observe reagent-dependent tunability and doping capabilities. See FIGS.7C-7E. As shown in annular dark field scanning transmission electron microscopy (ADF-STEM) and energy dispersive X-ray spectrometry (EDX), the atomic resolution images of SnS2(FIG.7C) and SnSe2(FIG.7D) indicate that the syntheses of these compounds were successful; EDX also showed similar results with the ADF- STEM imaging detecting Sn and S or Se, respectively. Remarkably, by simply substituting the initial precursor to SeS2, Se-doped SnS2(denoted as SnSxSey) was formed (FIG.7E). The EDX spectrum indicated the uniform distribution of Se with high crystallinity as observed in the ADF-STEM image. Due to the 2:1 ratio between S and Se, the Raman spectrum and XRD of SnSxSeyexhibits similar features as the SnS2. Additionally, all S / TEM (scanning / transmission electron microscopy) analyzed flakes exhibited single-crystalline orientation (FIGS.8A-8D), further showcasing the ability of FWF to produce phase-selective and single-crystalline bulk powders, a result rarely observed in other non-equilibrium methods.

[0211] As shown in inset picture 901 of FIG. 9B, for SnSe2, a small amount of SnO2was formed on the surface confirmed by XRD spectra shown in FIG.9A (also confirmed by EDX mapping (see FIG.7D)). As further shown in the inset pictures 901-903 of FIG.9B, the color of the powders dramatically changed from yellow (SnS2) to red (SnSxSey), indicating that doping and misalignment result in the bandgap shift in the material. [Chen 2011; Choi 2018].Attorney Docket No.: 072174-05601 This provides a simple and fast method to dope other atoms into the system, indicating doping procedure for applications in electronics [Shi 2020], catalysis [Dou 2020], and energy storage. [Zhu L 2023; Zhu W 2023]. Electron Microscopy Characterization & Electrical Properties of FWF Materials

[0212] FWF allows phase-controlled material synthesis. ADF-STEM images of MoSe2and WSe2(FIGS. 7F-7G) indicated that these materials exhibit hexagonal atomic configuration along with 2H-phase and AB stacking, presenting their energy favorable structure in the analyzed flake. [Förg 2021]. In contrast to the previous FJH method that produced metastable flash graphene with turbostratic configuration [Luong 2020], the FWF does not involve electric current passing through the sample during synthesis. This might account for the highly regular order in stacking. For In2Se3, as shown by ADF-STEM image (FIG.7H) and XRD, only alpha phase (α-In2Se3) was present in the flakes, indicating that the presently optimized FWF was a selective process. [Han 2023].

[0213] Understanding the electrical properties of FWF products has import since these synthesized materials can be widely adopted in numerous semiconductor applications. MoSe2, WSe2, and α-In2Se3flakes were targeted as representative because they exhibit n-type semiconductor, p-type semiconductor, and n-type ferroelectric behaviors, respectively. To characterize the electrical properties, FWF materials were mechanically exfoliated, and field- effect transistor (FET) devices 1000 were fabricated by conventional photolithographic methods on a SiO2 / Si substrate 1001. FIG.10A.

[0214] For the fabrication of the device 1000 shown in the schematic of FIG.10A, the MoSe21007, WSe21008, and α-In2Se31009 (both FWF α-In2Se3and commercial single crystal α- In2Se3purchased from 2D Semiconductors®) samples were prepared using the typical mechanical exfoliation method on SiO2(285 nm) / Si substrate, respectively. The thickness of their layers was verified by optical contrast, following which the cross-sectional TEM was usedAttorney Docket No.: 072174-05601 to determine the thickness of them. To make the electrical contact, a conventional photolithography was used to make the source 1003 and drain 1002 patterns where the channel length is 3 μm, and 50 nm of Au metal was deposited by an electron beam evaporator under a pressure of ~10-8Torr and deposition rate of 2.0 Å·s-1. To remove the residual photoresist, the sample was immersed in acetone bath for 6 h ~ 12 h, and then the solution was gently blown by N2gas. Finally, to enhance the interfacial contact properties between metal / 2D materials, the fabricated devices were stored for 6 h ~ 12 h under vacuum (~ 10-3Torr) conditions. Drain voltage (VD) 1004, gate voltage (VG) 1005, and source electrode ground 1006 are further shown in the schematic of device 1000 shown in FIG 10A.

[0215] Cross-sectional ADF-STEM and energy dispersive X-ray spectrometry (EDX) analyses were performed to obtain atomic resolution images of the devices along with their constituents (images 1011-1013 in FIG. 10B for MoSe2, WSe2and α-In2Se3, respectively) showing the layered structure, clean interfaces, and homogeneous atomic distribution.

[0216] To verify the electrical characteristics of as-synthesized materials, the transfer and output curves were investigated. For MoSe2, the transfer curve displayed an ON-current when a positive gate bias was applied regardless of drain voltages. FIG.10C (with plots 1021-1022 for VD= 0.1 V and 1 V, respectively, with insert 1023 showing the optical images of this FET device). In addition, the output curve showed higher drain current when the gate bias was positive (FIG.10F, with plots 1059, 1053, 1052, and 1051 for VD= -40V, 20V, 30V, and 40V, respectively), indicative of its n-type characteristics. [Jung 2015]. Conversely, for WSe2, the transfer curve exhibited an ON-current when a negative gate bias was applied regardless of drain voltages. FIG. 10D (with plots 1031-1032 for VD= 0.1 V and 1 V, respectively, with insert 933 showing the optical images of this FET device). Similarly, the output curve showed higher current when the gate bias was negative ((FIG.10G, with plots 1063, 1065, 1066, 1067, 1068, and 1051 for VD= 20V, 0V, -10V, -20V, -30V, and -40V, respectively), indicating typicalAttorney Docket No.: 072174-05601 p-type characteristics. [Kim 2023]. This showed that the FWF technique can generate n-type and p-type semiconducting flakes, achieving an ON / OFF ratio of 1.1 × 106and mobility of 6.81 cm2·V-1·s-1for MoSe2. For WSe2, an ON / OFF ratio of 1.74 × 104and mobility of 2.96 cm2·V-1·s-1were achieved.

[0217] In the case of α-In2Se3(FIG. 10E with plots 1041-1042 for VD= 0.1 V and 1 V, respectively, with insert 1043 showing the optical images of this FET device), the transfer curve demonstrated an ON-current with a positive gate bias, which is typical n-type semiconducting behavior. However, the curve also exhibited a clockwise hysteresis loop due to the ferroelectric characteristics of α-In2Se3. [Si 2019]. The endurance test was further conducted to observe the SET / RESET characteristic of α-In2Se3. During the endurance test the following sequence was repeated 1000 times: The gate voltage of -40 V with pulse width of 1 s was applied to make the SET state, and the channel current was subsequently measured by drain voltage of 1 V. After that, the gate voltage of +40 V with pulse width of 1 s was applied to make the RESET state, and the channel current was subsequently measured by drain voltage of 1 V.

[0218] As shown in FIG.10H, no degradation of performance was observed for 1,000 cycles with an ON / OFF ratio of ~102, suggesting a high durability that is comparable to chemical- vapor-deposition-grown α-In2Se3. [Si 2019]. The results show that the non-equilibrium FWF produced materials exhibit outstanding electrical properties that could facilitate the development of various devices with two-dimensional materials and promote fundamental research of these materials, now easily accessible in gram-scale with lowered cost (as set forth further below).

[0219] The comparison between commercially available single crystal α-In2Se3and the FWF α-In2Se3was done to demonstrate the comparability of performance between two materials. Since device geometries and pre / post treatment must be identical for valid comparisons, theAttorney Docket No.: 072174-05601 present FWF α-In2Se3device was compared to a commercial single crystal α-In2Se3(2D Semiconductors®) device fabricated under identical conditions. The output and transfer curve exhibited the expected higher drain current and clockwise hysteresis loop along with ON- current when the gate bias was positive, indicating ferroelectric, n-type semiconductor performance. The endurance test was also performed showing the SET / RESET characteristics. When compared to FWF, transfer curve, output curve, and endurance performance are all comparable between FWF materials and commercially available single crystals.

[0220] Previously reported works are summarized in TABLE II. A straight comparison between reported works and the devices disclosed and taught herein for MoSe2, WSe2, and α- In2Se3are not reliable due to differing geometries and fabrication protocols. Thus, providing the device performance comparison between the commercially available α-In2Se3single crystal and our FWF α-In2Se3was necessary to show the electronic similarities. TABLE II Comparison Of Performance And Device Parameters Between Previously Reported Works And HereinAttorney Docket No.: 072174-05601Tribology and Coefficient of Friction Comparison

[0221] A comparative analysis of coefficient of friction (COF) was made between the commercially available MoSe2and FWF MoSe2to demonstrate superior and stable tribological performance. For the tribology performance measurements, the samples were prepared by coating alumina substrates with commercial MoSe2powder (Millipore-Sigma) and FWF MoSe2powder. The powder was directly applied onto the substrates and meticulously spread by rubbing it against the surface for 5 min in a circular motion to disrupt heterogeneity and achieve the incorporation of the additive as a coating. To evaluate the tribological properties of the samples in sliding reciprocating motion, a tribometer with a ball-on-flat configuration was used. In this testing, a 6 mm diameter chrome steel 52100 ball was slid against a rectangular flat alumina sample under different load conditions: 1 N, 5 N, and 10 N, at a frequency of 3 Hz for 10 min. The coefficient of friction was measured and reported as a function of time, with a sampling rate of 100 data points per second. The mass of the coating was 0.2 g.

[0222] FIG.11A shows time-dependent COF change for 120,000 measurements of reference alumina (blurred squares 1101), commercial MoSe2(blurred circles 1102), and FWF MoSe2(blurred triangles 1103). Moving-average trend lines for the reference alumina (line 1104), commercial MoSe2(line 1105) and FWF MoSe2(line 1106) under 1 N are shown concurrently. As shown in FIG. 11A, in the initial stages of the test, the COF for commercial MoSe2and FWF MoSe2were effectively indistinguishable. However, after 2 min into operation, aAttorney Docket No.: 072174-05601 noticeable increase in COF for commercially available MoSe2was observed.

[0223] Similarly, FWF MoSe2outperformed commercially available MoSe2under different loads. FIG. 11B (bars 1011-1013 for alumina, commercial MoSe2, and FWF MoSe2, respectively). The coefficient of friction exhibited a reduction of 69%, 20%, and 41% at applied loads of 1 N, 5 N, and 10 N, respectively. These results reveal that the commercially available MoSe2film degraded and / or abraded at a faster rate than the FWF MoSe2film, indicating that the quality of the initial powders differed.

[0224] The EDX analysis on these two flakes was conducted to investigate the impurity concentration. Both materials exhibited no distinguishable impurity concentration, indicating that the impurities are not the source of the performance difference. The low concentration of oxygen impurities in FWF MoSe2can be attributed to the efficient outgassing. A careful mathematical model was built to describe the behavior of oxygen defects in MoSe2when exposed to extreme heat generated during the FWF process.

[0225] To study the degassing through density function theory (DFT) calculations [Dudarev 1998], the formation energy of O substitution of Se in the MoSe2crystal structure was calculated with the following equation:where ^^^^O−subis the DFT total energy of the 4×4 MoSe2supercell with two O atoms substituting two Se atoms, ^^^^ = 32 is total number of MoSe2units in the supercell, ^^^^MoSe2is the DFT energy per units in the defect-free MoSe2 crystal (layered structure, space group C1, lattice constants: a = b = 3.314 Å, c = 13.842 Å), ^^^^Mois the DFT energy per Mo atom in the BCC crystal of Mo metal, and ^^^^O2is the DFT energy of a free O2molecule.

[0226] The chemical potential of O2gas as a function of pressure p and temperature T was calculated following the equation [Reuter 2001]:Attorney Docket No.: 072174-05601 where the ^^^^0= 1 ^^^^ ^^^^ ^^^^, and the entropy ^^^^( ^^^^, ^^^^0) and enthalpy ^^^^( ^^^^, ^^^^0) are taken from the thermochemical tables. [Chase 1975].

[0227] The DFT methods were used as they are implemented in the Vienna Ab-initio Simulation Package (VASP). [Kresse 1996]. A plane wave expansion up to 500 eV was employed in combination with an all-electron-like projector augmented wave (PAW) potential. [Blöchl 1994]. Exchange-correlation was treated within the generalized gradient approximation (GGA) using the functional parameterized by Perdew-Burke-Ernserhof. [Perdew 1996]. The periodic condition was applied to the supercell or unit cell of crystal structures, with Brillouin zone integration converging over Monkhorst-Pack type meshes. [Monkhorst 1976]. In structure optimization using the conjugate-gradient algorithm as implemented in VASP, both the positions of atoms and the unit cells were fully relaxed so that the maximum force on each atom is smaller than 0.01 eV / Å.

[0228] The governing equation described the formation energy of oxygen defects in MoSe2relative to a free oxygen molecule. This equation depends on the internal pressure and temperature. The free energy became positive around at ~2000 K regardless of pressure, indicating that oxygen defects were effectively eliminated during the synthesis. The minute oxygen signal in EDX can be attributed to adsorbed air and possible self-limiting native oxide layer formation.

[0229] The source of difference between two materials is demonstrated at the edge of the flake where commercially available MoSe2showed an ~10 nm thick amorphous layer. FIGS.12A- 12B. In comparison, FWF MoSe2showed little to no amorphous edges, and ADF-STEM atomic resolution image indicates well-defined crystalline edges. FIGS. 12D-12E. The selected area electron diffraction (SAED) pattern depicted the presence of polycrystalline and amorphous constituents in commercial MoSe2(FIG. 12C), whereas single crystallinity is observed for FWF MoSe2(FIG.12F).Attorney Docket No.: 072174-05601

[0230] This superior and stable performance was due to the single-crystalline nature of FWF MoSe2, resulting in an overall lower coefficient of friction and enhanced tribological performance. [Liu 2018; Lee 2010; Huang 2018]. Due to the well-defined lamellar orientation of the FWF MoSe2coating material, these sheets can easily slide atop one another, thereby reducing resistance to motion, and consequently the coefficient of friction. Gram Scalability of FWF

[0231] An exceptional advantage of the FWF method is its scalability to gram-scale production without complications. Such high scalability is rarely observed in laboratory chemical syntheses, which often require additional engineering, apparatus setup, and / or alternative synthesis routes to ensure complete conversion of the materials. [Li 2021]. In contrast, FWF can be easily scaled by adjusting the voltage to accommodate the increase in reactant mass.

[0232] Further, the semi-closed inner reactor allows efficient outgassing, playing a critical role in allowing the incorporation of highly volatile reagents like chalcogens. Furthermore, outgassing prohibits oxygen infiltration and prevents cracking of the inner tube. As discussed and described above (WSe2-gram scale), scalability of FWF was shown by synthesizing WSe2from W and Se precursors and successfully achieved facile gram-scale production. See FIGS. 6A-6D. FIG.6A shows 1.11 g of WSe2that was synthesized in a single reaction. XRD analysis (FIG.6B) and X-ray photoelectron spectroscopy (XPS) spectra (FIGS.6C-6D) show highly pure, crystalline WSe2with no discernible byproduct or remnant of initial precursors. This representative WSe2-gram scale FWF synthesis reveals the remarkable scalability of the FWF process. Life Cycle Assessments (LCA) of FWF

[0233] Life-cycle assessments (LCA) of nanomaterials and not-yet industrialized processes can be difficult due to a large variety of field inhomogeneity and variety of product classes. For example, TMDs can be synthesized by a variety of different methods including modifiedAttorney Docket No.: 072174-05601 chemical vapor transport (CVT) or deposition processes, as well as flux growth methods. To ease direct comparison of the FWF method, only synthesis methods that result in similar products were considered. Thus, methods capable of producing single-crystal, multi-layered, low-defect density MoSe2, and not methods that produce single-layer, highly defective, or polycrystalline layers were considered. Very small production scales exist for most TMDs that cannot be exfoliated from naturally occurring minerals, such as MoS2and WS2. Resultingly, these other TMD products have high economic value but minimal market size, largely limited to academic use. A functional unit of 100 g of small, crystalline, MoSe2was used as this can be considered lab scale and allowed for comparison between published synthetic methods, while minimizing the impact of assumptions related to the hypothetical pilot-scale production. The FWF reaction pathway was compared to a molten Mg autoclave reaction and a CVT flux growth method. It should be noted that CVT flux growth can grow larger crystals than molten Mg and FWF reaction pathways.

[0234] The comprehensive life cycle assessment was conducted to compare the sustainability of FWF with the Mg-assisted autoclave synthesis [Upadhyay 2021] and chemical vapor transport (CVT) method [Ubaldini 2014] for synthesizing 100 g of MoSe2. [Hellweg 2014]. These two methods were chosen because the final product exhibits similar characteristics such as multilayers and high crystallinity. The cradle-to-gate LCA categorized the cumulative energy demand (FIG.13A), global warming potential (FIG.13B), and cumulative water usage (FIG. 13C). The LCA demonstrated that the FWF synthesis of MoSe2used 56%-83% less energy, produced 71%-94% less greenhouse gases, and consumed 90%-97% less water, compared to autoclave and CVT methods, respectively. A preliminary production cost (FIG. 13D) was afforded by a techno-economic assessment (TEA). The preliminary TEA indicated that, even without the sale of flash graphene, FWF provides significant cost savings in the preparation of inorganic materials, making it an attractive option for manufacturing.Attorney Docket No.: 072174-05601 Applications and Uses

[0235] FWF Joule heating techniques—non-equilibrium, ultrafast heat conduction methods— can be utilized to prepare various materials, including, for example, transition metal dichalcogenides (TMDs), Group-XIV dichalcogenides, and other non-TMD materials, each in under 5 seconds while in ambient conditions. FWF achieves enormous advantages in facile gram scalability and in sustainable manufacturing criteria when compared to other synthesis methods. Also, FWF allows the production of phase-selective and single-crystalline bulk powders, a phenomenon rarely observed by any other synthesis method. Furthermore, FWF MoSe2outperformed commercially available MoSe2in tribology, showcasing the quality of FWF materials. The capability for atom substitution and doping further shows the versatility of FWF as a general bulk inorganic materials synthesis protocol. Hence, FWF Joule heating techniques advance inorganic materials production while maintaining environmental consciousness by providing sustainable manufacturing that prioritizes energy efficiency, minimal water use, scalability, and the ability to generate diverse materials.

[0236] FWF also is able to achieve the production of amorphous carbon (examples listed above) due to the absence of current flowing directly through the material. This has been one of the major hurdles that FJH could not achieve.

[0237] Embodiments of the present invention thus permit the rapid synthesis of gram-scale crystalline transition metal dichalcogenides, which cannot normally be performed simultaneously with this quality and speed. Industrially, this could be scaled to kilogram and multikilogram scale syntheses in seconds per batch. Battery performance using SnS2as the anode has been successfully demonstrated. As shown, the capacity retention rate is almost 99% after three initial cycles, a very high number. With further optimization of conductivity (e.g., doping), the battery performance can be boosted that has higher capacity than a graphite anode.Attorney Docket No.: 072174-05601

[0238] The applicability of these products in semiconducting devices, and here specifically as transistors, has also been demonstrated.

[0239] The products of the processes of embodiments of the present invention can also be used in other optical and electronic devices.

[0240] Pulse schemes for applying the voltage pulses that control the flash Joule heating mechanism through controlled electronic modulation can be useful in some embodiments. Such pulse schemes can include variable frequency drive (VFD), pulse width modulation (PWM), proportional–integral–derivative (PID) control, three-term control, and combinations thereof. Such controlled electronic modulation are discuss in Tour ’193 PCT Application, which is incorporated herein in its entirety.

[0241] Accordingly, the processes of embodiments of the present invention are faster, more energy efficient, and less expensive than other methods in producing gram-scale transition metal dichalcogenides. The crystallinity of the products are comparable to that produced via chemical vapor deposition, which requires minutes to hours to perform.

[0242] These process are also kinetically, rather than thermodynamically driven, allowing the formation of products that are unable to be synthesized through many other methods. Compared to conventional flash Joule heating, this method allows for the formation of products that cannot normally be formed.

[0243] While embodiments of the invention have been shown and described, modifications thereof can be made by one skilled in the art without departing from the spirit and teachings of the invention. The embodiments described and the examples provided herein are exemplary only 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 invention. The scope of protection is not limited by the description set out above, but is only limited by the claims which follow, that scope including all equivalents of the subject matter of the claims.Attorney Docket No.: 072174-05601

[0244] The disclosures of all patents, patent applications, and publications cited herein are hereby incorporated herein by reference in their entirety, to the extent that they provide exemplary, procedural, or other details supplementary to those set forth herein.

[0245] Amounts and other numerical data may be presented herein in a range format. It is to 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 explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. For example, a numerical range of approximately 1 to approximately 4.5 should be interpreted to include not only the explicitly recited limits of 1 to approximately 4.5, but also to include individual numerals such as 2, 3, 4, and sub-ranges such as 1 to 3, 2 to 4, etc. The same principle applies to ranges reciting only one numerical value, such as “less than approximately 4.5,” which should be interpreted to include all of the above-recited values and ranges. Further, such an interpretation should apply regardless of the breadth of the range or the characteristic being described.

[0246] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to 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 now described.

[0247] Following long-standing patent law convention, the terms “a” and “an” mean “one or more” when used in this application, including the claims.

[0248] Unless otherwise indicated, all numbers expressing quantities of ingredients, reaction conditions, and so forth 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,Attorney Docket No.: 072174-05601 the numerical parameters set forth in this specification and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by the presently disclosed subject matter.

[0249] As used herein, the term “about” and “substantially” when referring to a value or to an amount of mass, weight, time, volume, concentration or percentage is meant to encompass variations 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% from the specified amount, as such variations are appropriate to perform the disclosed method.

[0250] As used herein, the term “substantially perpendicular” and “substantially parallel” is meant to encompass variations of in some embodiments within ±10° of the perpendicular and parallel directions, respectively, in some embodiments within ±5° of the perpendicular and parallel directions, respectively, in some embodiments within ±1° of the perpendicular and parallel directions, respectively, and in some embodiments within ±0.5° of the perpendicular and parallel directions, respectively.

[0251] As used herein, the term “and / or” when used in the context of a listing of entities, refers to the entities being present singly or in combination. Thus, for example, the phrase “A, B, C, and / or D” includes A, B, C, and D individually, but also includes any and all combinations and subcombinations of A, B, C, and D. REFERENCES

[0252] PCT Application No. PCT / US2019 / 047967, filed on August 23, 2019, entitled “Flash Joule Heating Synthesis Method And Compositions Thereof,” to J.M Tour et al. (“Tour ’967 PCT Application”).

[0253] PCT Application No. PCT / US2024 / 010193, filed on January 3, 2024, entitled “Methods For Controlled Joule Heating Of Materials For Gas Desorption And Systems ForAttorney Docket No.: 072174-05601 Performing Same,” to J.M Tour et al. (“Tour ’193 PCT Application”), which claims priority to U.S. Patent Application No. 63 / 437,021, filed January 4, 2023, entitled “Methods For Controlled Joule Heating Of Materials For Gas Desorption And Systems For Performing Same,” to J.M. Tour, et al.

[0254] U.S. Patent Appl. Serial No. 63 / 669,556, filed July 10, 2024, entitled “Systems And Methods For Extraction Of Lithium From Spodumene,” to J.M. Tour et al. (“Tour ’556 Application”).

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Claims

Attorney Docket No.: 072174-05601 WHAT IS CLAIMED IS:

1. A method comprising: (a) providing an inner feedstock within an inner vessel; (b) providing an outer feedstock within an outer vessel, wherein the inner vessel is within the outer vessel in a flash Joule heating apparatus; and (c) applying one or more voltage pulses, alternating current (AC), direct current (DC), or a combination thereof across the outer feedstock to subject the outer feedstock to a flash Joule heating process, whereby the flash Joule heating process upon the outer feedstock results in the conversion of the inner feedstock to a converted material.

2. The method of Claim 1, wherein the flash Joule heating process upon the outer feedstock provides conduction heating and / or radiative heating to the inner feedstock that result in the conversion of the inner feedstock to the converted material.

3. The method of Claim 1, wherein the converted material is a 2-dimensional material.

4. The method of Claim 1, wherein the converted material is selected from the group consisting of FeS2, CoS2, CoSxSey, CoSe, NiS2, NiSe2, Cu9S5, NbSe2, MoSe2, TiSe2, In2Se3, SnS2, SnSxSey, SnSe2, WSe2, WS2, Bi2S3, BixSySez, Bi2Se3, TiN, LaBO3, Cu2Se, Cu0.87Se, and combinations and mixtures thereof.

5. The method of Claim 1, wherein the converted material comprises chalcogenide, metal, and / or alloys.Attorney Docket No.: 072174-05601 6. The method of Claim 1, wherein the outer feedstock is selected from the group consisting of graphene, flash graphene, turbostratic graphene, anthracite coal, coconut shell- derived carbon, higher temperature-treated biochar, activated charcoal, calcined petroleum coke, metallurgical coke, coke, shungite, carbon nanotubes, asphaltenes, acetylene black, carbon black, ash, carbon fiber, graphite, and combinations and mixtures thereof.

7. The method of Claim 1, wherein the outer feedstock converts to flash graphene after applying the voltage pulse across the outer feedstock to subject the outer feedstock to a flash Joule heating process.

8. The method of Claim 7, wherein the flash graphene is re-used multiple times as the outer feedstock in the method of Claim 1.

9. The method of Claim 7 further comprising: (a) removing the converted material from the inner vessel; (b) providing a second inner feedstock within an inner vessel; and (c) applying one or more voltage pulses, AC, DC, or a combination thereof across the flash graphene in the outer vessel to subject the flash graphene to a flash Joule heating process, whereby the flash Joule heating process upon the flash graphene results in the conversion of the second inner feedstock to a second converted material.

10. The method of Claim 9, wherein (a) the second inner feedstock is a same type of feedstock as the inner feedstock converted into the converted material; andAttorney Docket No.: 072174-05601 (b) the second converted material is a same type as the converted material.

11. The method of Claim 9, wherein (a) the second inner feedstock is a different type of feedstock as the inner feedstock converted into the converted material; and (b) the second converted material is a different type from the converted material.

12. The method of Claim 1, wherein the step of applying the one or more voltage pulses utilizes DC voltage.

13. The method of Claim 1, wherein the step of applying the one or more voltage pulses utilizes pulsed DC.

14. The method of Claim 1, wherein the step of applying the one or more voltage pulses utilizes AC voltage.

15. The method of Claim 1, wherein the step of applying the one or more voltage pulses utilizes a combination of DC voltage and AC voltage.

16. The method of Claim 1, wherein (a) the step of applying the one or more voltage pulses, AC, DC, or a combination thereof comprises controlling the flash Joule heating process through controlled electronic modulation, and (b) the controlled electronic modulation occurs through a control selected from the group consisting of variable frequency drive (VFD), pulse width modulationAttorney Docket No.: 072174-05601 (PWM), proportional–integral–derivative (PID) control, three-term control, and combinations thereof.

17. The method of Claim 16, wherein the controlled electronic modulation utilizes (i) DC current (ii) a uniform, non-traveling AC current, or (iii) a combination thereof.

18. The method of Claim 1 further comprising applying an inner vessel current through the inner feedstock when applying the one or more voltage pulses, AC, DC, or a combination thereof across the outer feedstock.

19. An apparatus comprising: (a) an inner vessel operable for receiving an inner feedstock; (b) an outer vessel operable for receiving an outer feedstock, wherein the outer vessel is (i) a non-conductive vessel operable for constraining the outer feedstock or (ii) a conductive vessel operable to be directly flash Joule heated; and (c) electrodes that are operable for applying a voltage pulse, alternating current (AC), direct current (DC), or a combination thereof across the outer feedstock constrained within the outer vessel to subject the outer feedstock to a flash Joule heating process, wherein the flash Joule heating process upon the outer feedstock results in the conversion of the inner feedstock to a converted material.

20. The apparatus of Claim 19, wherein the converted material is a 2-dimensional material.Attorney Docket No.: 072174-05601 21. The apparatus of Claim 19, wherein the converted material is selected from the group consisting of FeS2, CoS2, CoSxSey, CoSe, NiS2, NiSe2, Cu9S5, NbSe2, MoSe2, TiSe2, In2Se3, SnS2, SnSxSey, SnSe2, WSe2, WS2, Bi2S3, BixSySez, Bi2Se3, TiN, LaBO3, Cu2Se, Cu0.87Se, and combinations and mixtures thereof.

22. The apparatus of Claim 19, wherein the converted material comprises chalcogenide, metal, and / or alloys.

23. The apparatus of Claim 19, wherein the outer feedstock is selected from the group consisting of graphene, flash graphene, turbostratic graphene, anthracite coal, coconut shell- derived carbon, higher temperature-treated biochar, activated charcoal, calcined petroleum coke, metallurgical coke, coke, shungite, carbon nanotubes, asphaltenes, acetylene black, carbon black, ash, carbon fiber, graphite, and combinations and mixtures thereof.

24. The apparatus of Claim 19, wherein the outer feedstock converts to flash graphene after applying the voltage pulse, AC, DC, or a combination thereof across the outer feedstock to subject the outer feedstock to a flash Joule heating process.

25. The apparatus of Claim 19 further comprising a controller that controls the flash Joule heating process applied by the electrodes through controlled electronic modulation, wherein (a) the controller is selected from the group consisting of variable frequency drive (VFD) controllers, pulse width modulation (PWM) controllers, proportional– integral–derivative (PID) control controllers, three-term control controllers, and combinations thereof.Attorney Docket No.: 072174-05601 26. The apparatus of Claim 19, wherein the controlled electronic modulation operably utilizes (i) DC current (ii) a uniform, non-traveling AC current, or (iii) a combination thereof.

27. The apparatus of Claim 19 further comprising inner vessel electrodes that are operable for applying an inner vessel current through the inner feedstock when applying the one or more voltage pulses, AC, DC, or a combination thereof across the outer feedstock.

28. An apparatus comprising: (a) an inner vessel operable for receiving a feedstock; (b) an outer vessel operable to provide a protective atmosphere or vacuum for a resistive heater; (c) the resistive heater within the outer vessel; (d) electrodes that are operable to provide AC or DC current to the resistive heater; and (e) plugs in the inner vessel to contain the feedstock therein.

29. The apparatus of Claim 28, wherein (a) the inner vessel is a transparent inner vessel; (b) the resistive heater is a tubular resistive heater; (c) the resistive heater is concentric within the outer vessel; and (c) the electrodes are tubular electrodes.

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