Method for producing platinum-supporting single crystal spherical carbon nanoparticles

Abstract

The present invention pertains to a method for producing platinum-supporting single crystal spherical carbon nanoparticles in which platinum particles are supported on the surfaces of single crystal spherical carbon nanoparticles, the present invention relates to a method for producing spherical single-crystal carbon nanoparticles, which comprises mixing a starting material solution of spherical single-crystal carbon nanoparticles containing a halocarbon with a reduction solution of platinum-supported spherical single-crystal carbon nanoparticles containing negative ions of an aromatic compound generated from lithium, sodium or potassium and the aromatic compound to produce spherical single-crystal carbon nanoparticles, and then continuously producing spherical single-crystal carbon nanoparticles. Platinum-supporting single crystal spherical carbon nanoparticles are produced by adding a platinum starting material solution containing a platinum halide to the obtained mixture. The platinum-supporting single-crystal spherical carbon nanoparticles produced by this production method do not have toxicity to organisms, can be filled with an electrode material or the like for a solar cell or a secondary ion battery at a high density, and can be used as a negative electrode for a lithium ion battery, a fuel cell catalyst, or an electrode material for a solar cell, having improved low conductivity.

Description

Technical Field

[0001] The invention relates to a method for preparing platinum-supported single-crystal spherical carbon nanoparticles. Background Art

[0002] Carbon nanoparticles are nanoparticles composed of carbon atoms. Those with a particle size of less than 10 nanometers are also called carbon quantum dots. Known quantum dots include those made of metal elements such as CdSe and CdTe that exhibit fluorescence. However, these quantum dots are not suitable for use in the human body, leading to the search for alternative materials.

[0003] It is known that carbon nanoparticles can be produced using either a top-down or bottom-up method. Top-down methods for producing carbon nanoparticles include methods that use laser ablation, arc discharge, or electrochemical methods to produce carbon nanoparticles from carbon materials of at least micrometer size, such as graphite, carbon nanotubes, and diamond. In contrast, bottom-up methods for producing carbon nanoparticles include methods known as hydrothermal methods, which involve heat treatment of pure water or an organic solvent under high-temperature and high-pressure conditions, and methods using chemical vapor deposition (CVD).

[0004] When carbon nanoparticles are used for drug delivery in the human body, they need to be hydrophilized. Therefore, the hydrophilization of the carbon nanoparticle surface is performed using an oxidizing agent, for example, after an oxidation reaction is carried out in the atmosphere or after a surfactant is mixed and dispersed in an aqueous solution. Furthermore, the hydrophilization of carbon nanoparticles in aqueous solutions containing surfactants requires a cleaning process to remove the treated surfactant, making this complex process a challenge.

[0005] Claim 1 of Patent Document 1 describes a carbon nanoparticle phosphor containing carbon atoms, oxygen atoms, nitrogen atoms, and, if necessary, hydrogen atoms. Due to the presence of CN and CO bonds, the carbon nanoparticle phosphor can be dispersed in an aqueous solution. Claim 9 discloses that the carbon nanoparticle phosphor is produced by a method comprising the steps of hydrothermal synthesis of a solution prepared by dissolving an organic substance selected from the group consisting of citric acid, benzoic acid, glucose, fructose, and sucrose, an amine, and one or more selected from an inorganic acid and acetic acid in a water-soluble solvent. However, no structural information regarding the carbon nanoparticle phosphor, namely, the spatial lattice, or the platinum-supported carbon nanoparticle phosphor is disclosed.

[0006] Patent Document 2 describes a carbon composite for an oxygen reduction catalyst containing nanosheet-shaped graphene oxide or its reduced product and carbon quantum dots (Claim 1). It also describes that the carbon quantum dots can be obtained by a conventional hydrothermal reaction, for example, by heating an aqueous solution containing a carbon source compound such as citric acid and a nitrogen source compound such as ethylenediamine at a temperature above the boiling point of water (Claim 6,

[0031] , etc.). However, there is no disclosure of single-crystalline, spherical carbon quantum dots or of platinum-supported carbon quantum dots.

[0007] Patent Document 3 describes a method for producing luminescent nanocarbon, comprising a reaction step of reacting a raw material solution containing a carbon source compound and a nitrogen source compound using a solvothermal synthesis method or the like (Claim 1,

[0013] ). The luminescent nanocarbon is produced using the same hydrothermal synthesis method as the method of Patent Document 1. However, there is no disclosure of single-crystal, spherical luminescent nanocarbon or platinum-supported luminescent nanocarbon.

[0008] Patent Document 4 describes a method for forming carbon dots, comprising the following steps: (a) mixing carbon powder with sulfuric acid and nitric acid to form a carbon powder mixture; (b) heating the carbon powder mixture under reflux to form a reflux carbon powder mixture; (c) cooling the reflux carbon powder mixture; and (d) neutralizing the reflux carbon powder mixture to form a neutralized carbon powder mixture containing soluble carbon dots (Claim 1,

[0036] ). The use of an acid in step (a) oxidizes the carbon powder to a quantum size of 1.5 to 6 nm (

[0037] ,

[0038] ). The carbon dots prepared by this formation method have abundant carboxyl groups on their surface, which can have negative charges (

[0048] ). The abundant carboxyl groups on the surface of the carbon dots distinguish them from the platinum-supported single-crystalline spherical carbon nanoparticles of the present invention. Furthermore, Patent Document 4 does not disclose that the carbon dots are single-crystalline, spherical, or that they support platinum.

[0009] Patent Document 5, filed by the applicant of the present application, describes a method for producing semiconductor microparticles using a fluid processing device having relatively rotating processing surfaces that can be approached and separated (Claim 1). Specific examples of semiconductor elements are also described (

[0037] ). However, there is no description of a specific embodiment in which the semiconductor element is carbon. Even based on Patent Document 5, the platinum-supported single-crystalline spherical carbon nanoparticles of the present invention cannot be obtained. Furthermore, Patent Document 5 does not disclose single crystals, spherical shapes, or platinum support.

[0010] Patent Document 6, filed by the applicant of the present application, describes a method for producing metal-supported carbon particles using a fluid processing device having relatively rotating processing surfaces that can be approached and separated (

[0221] to

[0263] ). For example, in Example B1, platinum-supported carbon black is produced by reacting a liquid containing a reducing agent mixed with carbon black with a dinitrodiamine platinum nitrate solution. However, the carbon black is used directly as a raw material, and there is no disclosure that the carbon particles are single crystal and spherical.

[0011] Patent Document 7 describes a fuel cell including a surface nanostructure 3 having catalyst nanoparticles 4 and carbon nanoparticles 5 composed of platinum (Claim 1, Figure 1 However, there is no disclosure that the carbon nanoparticles are single crystal and spherical.

[0012] Non-Patent Document 1 describes the synthesis of amine-terminated carbon quantum dots by reducing carbon tetrachloride with a hydride reducing agent such as lithium aluminum hydride, followed by reaction with an arylamine in the presence of a platinum catalyst. The carbon quantum dots described in Non-Patent Document 1 differ from the platinum-supported single-crystalline spherical carbon nanoparticles of the present invention because they have NH2 groups on their surfaces. Furthermore, Non-Patent Document 1 does not disclose single-crystalline, spherical carbon quantum dots or platinum-supported carbon quantum dots.

[0013] Prior art literature Patent Literature Patent Document 1: WO2018 / 163955 Patent Document 2: Japanese Patent Application Laid-Open No. 2019-155349 Patent Document 3: Japanese Patent Application Laid-Open No. 2021-183548 Patent Document 4: Japanese Patent Application No. 2019-511442 Patent Document 5: Japanese Patent No. 4458202 Patent Document 6: Japanese Patent No. 5500597 Patent Document 7: WO2009 / 128203 Non-patent literature Non-patent literature 1: Journal of Materials Chemistry, Volume 2, pp. 6025-6031 (2014) Summary of the Invention Problems to be solved by the invention The present invention aims to provide a method for producing carbon nanoparticles that can be used as a non-toxic catalyst and electrode material, improve the conductivity of the electrode material of a secondary battery, and be packed at a higher density.

[0014] Means used to solve problems The present inventors conducted intensive research to solve the above-mentioned problems and found that platinum-supported single-crystalline spherical carbon nanoparticles can be produced by using a reducing agent containing anions of aromatic compounds generated by mixing lithium, sodium or potassium with aromatic compounds, reacting it with a solution containing a carbon halide, and then continuously reacting it with a solution containing a platinum halide. It was also found that the produced platinum-supported single-crystalline spherical carbon nanoparticles can be used as electrodes for batteries to improve the conductivity of conventional carbon nanoparticles, thereby increasing the battery filling density and can also be used as a non-toxic catalyst, thereby completing the present invention.

[0015] That is, the present invention is as follows.

[0016] [1] A method for producing platinum-supported single-crystalline spherical carbon nanoparticles, wherein the platinum-supported single-crystalline spherical carbon nanoparticles have platinum particles supported on the surface of the single-crystalline spherical carbon nanoparticles, the method comprising: The single-crystal spherical carbon nanoparticle raw material solution containing a halogenated carbon and a platinum-supported single-crystal spherical carbon nanoparticle reducing solution containing anions of the aromatic compound generated from lithium, sodium or potassium and the aromatic compound are mixed to produce the single-crystal spherical carbon nanoparticles. Then, a platinum raw material solution containing platinum halide is continuously added to the obtained mixture to produce platinum-supported single-crystal spherical carbon nanoparticles.

[0017] [2] The manufacturing method according to [1], using the perimeter Z and area S of the projected image of the single-crystal spherical carbon nanoparticles observed by transmission electron microscopy, is calculated using the mathematical formula: 4πS / Z 2 The calculated average value of the circularity was 0.80 or more.

[0018] [3] The production method according to [1] or [2], wherein the average particle size of the single-crystal spherical carbon nanoparticles is 1 nm to 200 nm.

[0019] [4] The production method according to any one of [1] to [3], wherein the single-crystal spherical carbon nanoparticle raw material solution and the platinum-supported single-crystal spherical carbon nanoparticle reduction solution are mixed using the following apparatus to produce single-crystal spherical carbon nanoparticles, Then, a platinum raw material solution containing platinum halide is continuously added to the obtained mixture to produce platinum-supported single-crystal spherical carbon nanoparticles. The device comprises: a fluid pressure applying mechanism for applying pressure to a fluid to be processed; at least two processing parts, a first processing part and a second processing part, wherein the second processing part can be relatively close to or separated from the first processing part; and a rotation driving mechanism for rotating the first processing part and the second processing part relative to each other. At least two processing surfaces, a first processing surface and a second processing surface, are provided at positions facing each other in each of the processing parts. Each of the processing surfaces constitutes a part of a sealed flow path for a pressurized processed fluid to flow. Between the two processing surfaces, two or more processed fluids, at least one of which contains a reactant, are mixed and reacted. In the first processing part and the second processing part, at least the second processing part has a pressure-bearing surface, and at least a part of the pressure-bearing surface is composed of the second processing surface. The pressure-bearing surface is subjected to the pressure applied by the fluid pressure applying mechanism to the processed fluid, thereby generating a force that moves the second processing surface in a direction away from the first processing surface, thereby being able to approach or separate. By allowing the processed fluid to be pressurized to pass between the relatively rotating first processing surface and the second processing surface, the processed fluid forms a thin film fluid, and further has another inlet path independent of the flow path between each processing surface for the processed fluid to flow. At least either one of the first processing surface and the second processing surface has at least one opening connected to the another inlet path. By introducing at least one processed fluid sent from the another inlet path between the two processing surfaces, the reactant contained in at least any one of the processed fluids and the processed fluid different from the processed fluid are mixed in the thin film fluid.

[0020] [5] According to the manufacturing method described in [4], the opening is provided at a position downstream of a point where the flow of the processed fluid passing between the two processing surfaces becomes laminar.

[0021] [6] The production method according to any one of [1] to [5], wherein the molar ratio of the lithium, sodium or potassium to the carbon halide is 7:1 to 4:1.

[0022] [7] The production method according to any one of [1] to [6], wherein the aromatic compound is at least one selected from the group consisting of biphenyl, naphthalene, 1,2-dihydronaphthalene, anthracene, phenanthrene, and pyrene.

[0023] [8] According to the production method described in [7], when the aromatic compound is biphenyl, naphthalene or anthracene, in the IR absorption spectrum of the platinum-supported single-crystal spherical carbon nanoparticle reduction solution, the -1 ~1100cm -1 The wavenumber range shows the absorption peak.

[0024] [9] The production method according to any one of [1] to [8], wherein the aromatic compound is biphenyl, naphthalene or anthracene, in the platinum-supported single-crystal spherical carbon nanoparticle reduction solution 7In the Li-NMR spectrum, a peak due to chemical shift appears at 2 ppm or higher.

[0025]

[10] The production method according to any one of [1] to [9], in which the aromatic compound is biphenyl, naphthalene or anthracene, in the platinum-supported single-crystal spherical carbon nanoparticle reduction solution 1 The H-NMR spectrum showed at least four peaks due to chemical shifts from 5.5 ppm to 6.5 ppm.

[0026]

[11] According to the production method described in any one of [1] to

[10] , the solvent contained in the platinum-supported single-crystal spherical carbon nanoparticle reduction solution is tetrahydrofuran, 2-methyltetrahydrofuran, or dimethoxyethane with a residual water content of 10 ppm or less.

[0027]

[12] According to the production method described in any one of [1] to

[11] , the solvent contained in the platinum-supported single-crystal spherical carbon nanoparticle reduction solution is tetrahydrofuran containing a phenolic polymerization inhibitor, a residual water content of less than 10 ppm, and a residual oxygen concentration of less than 0.1 ppm.

[0028]

[13] According to the manufacturing method described in any one of [1] to

[12] , the solvent contained in the raw material liquid of the platinum-supported single-crystal spherical carbon nanoparticles is tetrahydrofuran, 2-methyltetrahydrofuran or dimethoxyethane with a residual water content of less than 10 ppm and a residual oxygen concentration of less than 0.1 ppm.

[0029]

[14] The production method according to any one of [1] to

[13] , wherein the carbon halide is carbon tetrachloride, carbon tetrabromide or carbon tetraiodide.

[0030]

[15] The production method according to any one of [1] to

[14] , wherein the platinum halide is hexachloroplatinic acid (IV) hexahydrate or platinum (IV) chloride.

[0031]

[16] The production method according to any one of [1] to

[15] , wherein the single-crystal spherical carbon nanoparticles are hexagonal.

[0032]

[17] The production method according to any one of [1] to

[16] , wherein the platinum-supported single-crystal spherical carbon nanoparticles have an IR absorption spectrum at 2800 cm -1 ~3000cm -1 The wavenumber range shows the absorption peak, for 900cm -1 ~1900cm -1 The 1000 cm -1 ~1100cm -1 The absorption peak area relative to 900 cm -1 ~1900cm-1 The total area of ​​the wavenumber range is less than 15%.

[0033]

[18] The production method according to any one of [1] to

[17] , wherein the platinum-supported single-crystal spherical carbon nanoparticles have an IR absorption spectrum of 900 cm -1 ~1900cm -1 The 1300 cm -1 ~1400cm -1 The absorption peak area relative to 900 cm -1 ~1900cm -1 The total area of ​​the wavenumber range is less than 10%.

[0034]

[19] According to the production method described in any one of [1] to

[18] , the platinum-supported single-crystal spherical carbon nanoparticles produce maximum fluorescence in the wavelength range of 400nm to 500nm in the fluorescence spectrum with an excitation wavelength of 240nm.

[0035]

[20] A platinum-supported single-crystal spherical carbon nanoparticle, wherein platinum is supported on the surface of the single-crystal spherical carbon nanoparticle with an average particle size of 1 nm to 30 nm.

[0036] Effects of the Invention According to the manufacture method of the present invention, it is possible to manufacture platinum particle-supported single crystal spherical carbon nanoparticles. The platinum-supported single crystal spherical carbon nanoparticles manufactured with the manufacture method of the present invention are owing to being supported by platinum particles with excellent electrical conductivity, and therefore can improve the electrical conductivity of carbon nanoparticles. In addition, owing to not having the toxicity to organisms possessed by compound semiconductors formed by cadmium, selenium, tellurium, etc., there is no need to reclaim them after being used as catalysts or battery materials. Further, owing to being spherical, it is possible to fill the electrode materials of solar cells or secondary ion batteries with high density, and can be used as the negative pole of lithium ion batteries, fuel cell catalysts, and electrode materials of solar cells. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 The IR absorption spectrum of naphthalene anions in a reducing solution of platinum particle-supported single-crystalline spherical carbon nanoparticles is shown.

[0038] Figure 2 The reduction solution of platinum particle-supported single-crystal spherical carbon nanoparticles is shown. 1 H-NMR spectrum.

[0039] Figure 3 The reduction solution of platinum particle-supported single-crystal spherical carbon nanoparticles is shown. 7 Li-NMR spectroscopy.

[0040] Figure 4TEM observation images of platinum-supported single-crystalline spherical carbon nanoparticles produced in Example 1-1 are shown.

[0041] Figure 5 Shown are TEM observation images of platinum supported on the platinum-supported single-crystalline spherical carbon nanoparticles produced in Example 1-1 and the measured values ​​of the length of the five-plane spacing.

[0042] Figure 6 Shown are STEM observation images of the platinum-supported single-crystalline spherical carbon nanoparticles produced in Example 1-2 and line analysis of platinum by STEM-EDS.

[0043] Figure 7 The IR spectrum and waveform separation spectrum (2800 cm -1 ~3000cm -1 ).

[0044] Figure 8 The IR spectrum and waveform separation spectrum (900 cm-1) of the platinum-supported single-crystal spherical carbon nanoparticles prepared in Example 1-1 are shown. -1 ~1900cm -1 ).

[0045] Figure 9 The fluorescence spectrum of the platinum-supported single-crystalline spherical carbon nanoparticles produced in Example 1-2 is shown.

[0046] Figure 10 The X-ray diffraction patterns of the platinum-supported single-crystalline spherical carbon nanoparticles produced in Example 1-4 are shown.

[0047] Figure 11 Shown are STEM observation images of the platinum-supported single-crystalline spherical carbon nanoparticles produced in Example 3-1 and surface analysis of platinum by STEM-EDS. DETAILED DESCRIPTION

[0048] The following describes embodiments of the present invention. However, the present invention is not limited to the embodiments described below. Furthermore, although the present invention is described as an example of a fluorescent light-emitting material, the uses of the platinum-supported single-crystal spherical carbon nanoparticles produced by the production method of the present invention are not limited to this application.

[0049] 1. Platinum-supported single-crystal spherical carbon nanoparticles The platinum-supported single-crystalline spherical carbon nanoparticles manufactured by the manufacturing method of the present invention have platinum particles supported on the surface of the single-crystalline spherical carbon nanoparticles. The single-crystalline spherical carbon nanoparticles contained in the platinum-supported single-crystalline spherical carbon nanoparticles are single crystals and spherical. The average particle size of the single-crystalline spherical carbon nanoparticles is preferably 1nm to 200nm. When the average particle size is greater than 200nm, it is difficult to perform high-density filling when the platinum-supported single-crystalline spherical carbon nanoparticles are used as negative electrode materials for secondary batteries. The single-crystalline spherical carbon nanoparticles are hexagonal. The spatial lattice of the hexagonal crystal can adopt a simple lattice and a rhombohedral lattice structure. The single-crystalline spherical carbon nanoparticles are spherical or approximately spherical. Preferably, the perimeter (Z) and area (S) of the projected image of the single-crystalline spherical carbon nanoparticles observed by a transmission electron microscope are used, and the mathematical formula is: 4πS / Z 2 The calculated average value of the circularity is 0.85 or greater, more preferably 0.90 or greater, and even more preferably 0.95 or greater. When utilizing fluorescence from platinum-supported single-crystalline spherical carbon nanoparticles, the average particle size of the single-crystalline spherical carbon nanoparticles is preferably 1.2 nm to 10 nm, more preferably 1.5 nm to 7 nm, and even more preferably 2 nm to 5 nm.

[0050] The average particle size of the platinum particles is, for example, 1 nm to 10 nm, preferably 1.5 nm to 5 nm, more preferably 1 nm to 3 nm, and even more preferably 0.2 nm to 2 nm.

[0051] Carbon has various structures and is also known to have sp 2 The C=C bond formed by the carbon atoms of the hybrid orbital is the structure of the basic graphene layer, the graphite in which the graphene layers are stacked in the c-axis direction, or the carbon nanotube. However, since they do not have a band gap, the excited electrons generated by the excitation light and the electron holes after the excited electrons are separated, that is, the holes, immediately recombine and no fluorescence is generated. Therefore, the sp 2 Carbon atoms with hybrid orbitals need to be able to generate a band gap in some way. One method for this is to place sp atoms in the graphene layer. 2 The bonding region of the carbon atom of the hybrid orbital is cut off, and an sp-type hybrid orbital generated by bonding with a carbon atom or an element other than a carbon atom is introduced. 3 Hybrid orbitals of carbon atoms. 3 The bonding of carbon atoms in hybrid orbitals can generate C-H bonds or C-O bonds by bonding hydrogen or oxygen at the ends of the graphene layer. Therefore, it is preferred that the carbon particles have a structure in which graphene layers constituting single-crystal spherical carbon nanoparticles are stacked, C-H bonds are present within the graphene layers, and C-O bonds are present at the ends of the graphene layers. The surface functional groups of single-crystal spherical carbon nanoparticles can be detected, for example, by the 2800 cm-1 wavelength attributable to the stretching vibration of the C-H bonds in the IR absorption spectrum.-1 ~2950cm -1 The wavenumber region of 1000 cm-1 and the stretching vibration of CO bond -1 ~1100cm -1 The platinum-supported single-crystal spherical carbon nanoparticles of Example 1-1 are as follows. Figure 7 and Figure 8 As described in , after waveform separation at 2932cm -1 and 2957cm -1 、2856cm -1 and 2871cm -1 There is an absorption peak generated by the C-H bond, and another peak at 1056 cm -1 The presence of an absorption peak due to a CO bond confirms the presence of sp 3 The hybridization of orbitals of carbon atoms causes structural changes that contribute to the generation of the band gap.

[0052] Preferred examples of platinum-supported single-crystal spherical carbon nanoparticles include platinum-supported single-crystal spherical carbon particles having an IR absorption spectrum of 900 cm -1 ~1900cm -1 The 1000 cm -1 ~1100cm -1 The area of ​​the absorption peak (stretching vibration of CO bond) relative to 900 cm -1 ~1900cm -1 The total area of ​​the wavenumber range is 15% or less (ratio of CO bonds), more preferably 2% or more and 15% or less, further preferably 2% or more and 10% or less, and even more preferably 2% or more and 8.5% or less.

[0053] Preferred examples of platinum-supported single-crystal spherical carbon nanoparticles include spherical carbon nanoparticles that emit maximum fluorescence within a wavelength range of 400 nm to 600 nm in a fluorescence spectrum.

[0054] Preferred examples of platinum-supported single-crystal spherical carbon nanoparticles include platinum-supported single-crystal spherical carbon nanoparticles having an IR absorption spectrum of 900 cm -1 ~1900cm -1 The 1300 cm -1 ~1400cm -1 The absorption peak area relative to 900 cm -1 ~1900cm -1 The total area of ​​the wavenumber range is 10% or less (ratio of CN bonds), more preferably 8% or less, and further preferably 6.5% or less.

[0055] It is known that the fluorescence of carbon nanoparticles occurs through the following three different mechanisms.

[0056] (A) By importing the sp 3 The fluorescence color is controlled by changing the electron energy band gap, a key physical factor, by adjusting the particle size of carbon nanoparticles containing hybrid orbital carbon atoms (known as the quantum effect). (B) By treating the surface of carbon nanoparticles with various chemical substances, various substituents such as alkyl or amino groups with different molecular chain lengths are chemically bonded to the surface of the carbon nanoparticles, and the fluorescence color is controlled via the surface substituents. (C) Controlling the fluorescence color by utilizing chemical factors generated by changes in the composition of oxygen or nitrogen contained in carbon nanoparticles The platinum-supported single-crystalline spherical carbon nanoparticles of the present invention produce fluorescence through the synergistic action of the three mechanisms (A) to (C) above: (A) the quantum effect mechanism and (C) the oxygen-mediated mechanism. This mechanism differs from the amino-terminated carbon nanoparticles described in Non-Patent Document 1, which utilize both the (A) quantum effect mechanism and the (B) surface modification mechanism. The platinum-supported single-crystalline spherical carbon nanoparticles of the present invention preferably exhibit maximum fluorescence within a wavelength range of 400 to 600 nm.

[0057] 2. Method for producing platinum-supported single-crystalline spherical carbon nanoparticles The present invention provides a method for producing platinum-supported single-crystalline spherical carbon nanoparticles, wherein the platinum-supported single-crystalline spherical carbon nanoparticles have platinum particles supported on their surfaces. The method comprises: mixing a single-crystalline spherical carbon nanoparticle raw material solution (Solution B) containing a carbon halide with a platinum-supported single-crystalline spherical carbon nanoparticle reducing solution (Solution A) containing anions of the aromatic compound generated from lithium, sodium, or potassium and an aromatic compound to produce the single-crystalline spherical carbon nanoparticles; and then continuously adding a platinum raw material solution (Solution C) containing a platinum halide to the resulting mixture to produce the platinum-supported single-crystalline spherical carbon nanoparticles. For example, the single-crystalline spherical carbon nanoparticle raw material solution (Solution B) and the platinum raw material solution (Solution C) are mixed with the platinum-supported single-crystalline spherical carbon nanoparticle reducing solution (Solution A) in a thin film fluid formed between two processing surfaces that are disposed oppositely, are accessible and separable, and at least one of which rotates relative to the other, thereby continuously producing the platinum-supported single-crystalline spherical carbon nanoparticles.

[0058] (Single-crystal spherical carbon nanoparticle raw material solution (Solution B)) The raw material for the single-crystal spherical carbon nanoparticles is not particularly limited as long as it can precipitate single-crystal spherical carbon nanoparticles by reduction. Preferred raw materials include carbon tetrahalides, more preferably carbon tetrachloride, carbon tetrabromide, and carbon tetraiodide. Further preferred raw materials include carbon tetrachloride and carbon tetrabromide.

[0059] (Platinum raw material solution (Solution C)) The raw material for the platinum particles supported on the single-crystal spherical carbon nanoparticles is not particularly limited as long as it can support the platinum particles on the surface of the single-crystal spherical carbon nanoparticles through reduction. Preferred raw materials include platinum halides, with chloroplatinic acid (IV) hexahydrate (H2PtCl6･6H2O) and platinum (IV) chloride (PtCl4) being particularly preferred.

[0060] (Solvent) The solvents for the platinum-supported single-crystalline spherical carbon nanoparticle reduction solution (Solution A), the single-crystalline spherical carbon nanoparticle raw material solution (Solution B), and the platinum raw material solution (Solution C) are not particularly limited, as long as they can dissolve the single-crystalline spherical carbon nanoparticle raw material and the platinum raw material, reduce the platinum raw material and support the platinum particles on the single-crystalline spherical carbon nanoparticles, do not interfere with the reduction reaction, and are inactive. Preferred solvents include ethers, more preferably tetrahydrofuran (THF), 2-methyltetrahydrofuran, 1,2-dimethoxyethane (DME), or mixtures thereof, and even more preferably THF or 2-methyltetrahydrofuran.

[0061] (Residual moisture / residual oxygen in solvent) It is preferred to use a solvent with a residual water content of 10 ppm or less in the platinum-supported single-crystalline spherical carbon nanoparticle reducing solution (Solution A), the single-crystalline spherical carbon nanoparticle raw material solution (Solution B), and the platinum raw material solution (Solution C). This is because when producing single-crystalline spherical carbon nanoparticles through a reduction reaction in a solvent, if the residual water content exceeds 10 ppm, oxidation of the graphene layers becomes significant, causing distortion of the graphite structure formed by stacking the graphene layers in the c-axis direction. This prevents the graphene layers from stacking, resulting in the failure to form single-crystalline spherical carbon nanoparticles. The residual oxygen concentration in the solvent used in the present invention is preferably less than 0.1 ppm.

[0062] (Platinum-supported single-crystal spherical carbon nanoparticle reduction solution (Solution A)) The reducing species contained in the platinum-supported single-crystalline spherical carbon nanoparticle reducing solution is not particularly limited as long as it is a raw material and a platinum raw material capable of reducing the single-crystalline spherical carbon nanoparticles contained in the platinum-supported single-crystalline spherical carbon nanoparticle raw material solution and precipitating the platinum particles as platinum-supported single-crystalline spherical carbon nanoparticles. Examples of the reducing species include combinations of metallic lithium, sodium, or potassium and aromatic compounds, and more preferably combinations of metallic lithium and aromatic compounds.

[0063] Examples of aromatic compounds include those that can transfer a single electron from metallic lithium to the aromatic compound, generating a lithium cation and an aromatic anion. The aromatic anion to which the single electron has been transferred is an anion radical because it has a single electron in the lowest unoccupied molecular orbital (LUMO) of the aromatic compound. For example, if carbon tetrachloride is used as the raw material for single-crystal spherical carbon nanoparticles, the reduction potential of carbon tetrachloride is -1.9 V. Therefore, in order to reduce carbon tetrachloride to carbon nanoparticles, the potential of the aromatic anion must be below -1.9 V. The potential here refers to the value relative to silver (Ag) / silver chloride (AgCl), which serves as a reference electrode. Examples of aromatic compounds with a potential lower than -1.9 V include naphthalene (-2.53 V), biphenyl (-2.68 V), 1,2-dihydronaphthalene (-2.57 V), phenanthrene (-2.49 V), anthracene (-2.04 V), pyrene (-2.13 V), or mixtures thereof, with naphthalene and biphenyl being preferred. On the other hand, tetracene (-1.55 V) and azulene (-1.62 V) are not suitable for reduction with carbon tetrachloride.

[0064] The molar ratio of metallic lithium, sodium or potassium to the aromatic compound is, for example, 1:1 to 1:5, preferably 1:1 to 1:1.5, and more preferably 1:1 to 1:1.2.

[0065] The molar ratio of metallic lithium, sodium, or potassium to the raw material of single-crystalline spherical carbon nanoparticles can be, for example, 10:1 to 1.2:1, preferably 7:1 to 1.5:1, and more preferably 5:1 to 3:1. It is preferable to use metallic lithium, sodium, or potassium in excess relative to the raw material of the single-crystalline spherical carbon nanoparticles. Using an excess amount allows the production of platinum-supported single-crystalline spherical carbon nanoparticles. When metallic lithium, sodium, or potassium is used in an amount less than three-quarters of the raw material of the single-crystalline spherical carbon nanoparticles, the particles are not completely reduced, resulting in residual halogen atoms from the raw material in the single-crystalline spherical carbon nanoparticles, which are not spherical. Examples of solvents for the reduction solution of platinum-supported single-crystalline spherical carbon nanoparticles include the solvents described above for the raw material solution of the single-crystalline spherical carbon nanoparticles. The concentration of metallic lithium, sodium, or potassium in the reduction solution of platinum-supported single-crystalline spherical carbon nanoparticles is not particularly limited but can be determined based on the molar ratio of metallic lithium, sodium, or potassium to the raw material of the single-crystalline spherical carbon nanoparticles described above.

[0066] (Storage of reducing fluid at low temperature) Alkali metals can be dissolved in ether organic solvents in the presence of aromatic compounds, but the reducing power is obtained by the electrons generated by the dissolution of the alkali metal moving to the LUMO of the aromatic compound to form an aromatic compound anion. If the structure of the reducing solution that generates the reducing power is described as metallic lithium for the alkali metal, naphthalene (NPT) for the aromatic compound, and THF for the solvent, it is preferred that the lithium cation (Li + ) and naphthalene anion (NPT･ - ) is directly bonded by Coulomb force without solvent (Li + ･NPT･ - ), the structure of the solvent THF between the lithium cation and the naphthalene anion (Li + ･THF･NPT･ - When the solution is stored at a temperature above 25°C, the lithium cation (Li + ) and naphthalene anion (NPT･ - ) are solvated separately, and the solvated structures (Li + ･THF･THF･NPT･ - ) are bonded by Coulomb force, which leads to a problem of reduced power. Therefore, in the production method based on the present invention, the temperature of the reduction solution after the production of platinum-supported single-crystal spherical carbon nanoparticles is controlled to be less than 10°C, and the reduction solution is controlled to be based on naphthalene anion (NPT･ - ) and lithium cations (Li + ) can exist stably, thereby maintaining the reducing force.

[0067] (solvation at low temperatures) The reducing power is highest when the alkali metal cations and aromatic compound anions are directly bonded without a solvent. Maintaining this state can suppress the particle size distribution of carbon nanoparticles. When the reducing solution is stored at temperatures above 25°C, the probability of solvent molecules intervening between these anions increases. When the solution is prepared in a state where the ions are directly bonded to each other by Coulombic forces and reach equilibrium, and then stored at low temperatures, it is difficult for solvent molecules to overcome the Coulombic forces between the alkali metal cations and aromatic compound anions and penetrate between them. Therefore, the storage temperature after preparation is crucial.

[0068] (Solvent reduction inhibition) Storing the reducing solution at low temperatures is necessary to maintain the high reducing power and the resulting size distribution of the platinum-supported single-crystalline spherical carbon nanoparticles, as described above. Furthermore, if aromatic anions with high reducing power are present in the solvent, low-temperature storage is also preferred for the stability of the solvent after the reducing solution is prepared. If the reducing solution is stored at a high temperature, using a cyclic ether such as THF as the solvent will cause a reduction polymerization reaction of the THF due to the aromatic anions. If a polymer is produced by the polymerization of a cyclic ether such as THF, the THF ring-opened compound generated by the reduction of the halocarbon will be mixed with the single-crystalline spherical carbon nanoparticles. Therefore, it is preferable to suppress the polymerization reaction. Examples of THF polymerization inhibitors include phenolic polymerization inhibitors added to suppress the formation of peroxides of cyclic ethers such as THF, with BHT (2,6-di-tert-butyl-4-methylphenol) being a preferred example. Furthermore, using a solvent more stable than THF, such as 2-methyltetrahydrofuran, can further stabilize the solvent.

[0069] (Method for producing platinum-supported single-crystalline spherical carbon nanoparticles: Apparatus) The platinum-supported single-crystalline spherical carbon nanoparticles of the present invention can be produced, for example, by mixing a single-crystalline spherical carbon nanoparticle raw material liquid (liquid B) with a platinum-supported single-crystalline spherical carbon nanoparticle reduction liquid (liquid A) in a thin film fluid formed between two processing surfaces that are arranged oppositely, are accessible and separable, and at least one of which rotates relative to the other, and then continuously mixing with a liquid containing a platinum raw material (liquid C).

[0070] As an apparatus used in the manufacturing method of the present invention, for example, a fluid treatment apparatus described in Japanese Patent Application Laid-Open No. 2009-112892 proposed by the applicant of the present application can be cited. The apparatus comprises: a stirring tank having an inner peripheral surface with a circular cross-section; and a stirring tool attached to the inner peripheral surface of the stirring tank with a small gap therebetween, the stirring tank having at least two fluid inlets and at least one fluid outlet, a first treated fluid containing one of the reactants in the treated fluid is introduced into the stirring tank from one of the fluid inlets, and a second treated fluid containing one of the reactants different from the reactants is introduced into the stirring tank from another of the fluid inlets through a flow path different from the first treated fluid. The treated fluid is formed into a thin film state by rotating at high speed at least one of the stirring tank and the stirring tool relative to the other, and the reactants contained in at least the first treated fluid and the second treated fluid react with each other in the thin film. In addition, an apparatus based on the same principle as the fluid treatment apparatus described in Patent Documents 6 and 7 can be cited.

[0071] Single-crystalline spherical carbon nanoparticles are preferably produced by mixing a single-crystalline spherical carbon nanoparticle raw material solution (Solution B) and a platinum-supported single-crystalline spherical carbon nanoparticle reducing solution (Solution A) in the thin film fluid. Single-crystalline spherical carbon nanoparticles are produced through a two-stage process: first, graphene layers, which serve as the cores of the single-crystalline spherical carbon nanoparticles, are generated. These layers are then stacked to form the single-crystalline spherical carbon nanoparticles. Furthermore, platinum-supported single-crystalline spherical carbon nanoparticles can be produced by mixing a platinum raw material solution (Solution C). When producing platinum-supported single-crystalline spherical carbon nanoparticles, using Solution A at a temperature below 20°C and mixing Solution B to initiate the reduction reaction reduces the frequency of nuclei generated for the growth of single-crystalline spherical carbon nanoparticles, thereby suppressing the frequency of contact between the graphene layers, the cores of the single-crystalline spherical carbon nanoparticles. By controlling the nucleation rate of the single-crystalline spherical carbon nanoparticles, the platinum-supported single-crystalline spherical carbon nanoparticles can be miniaturized.

[0072] In the production of platinum-supported single-crystalline spherical carbon nanoparticles, when carbon tetrachloride, carbon tetrabromide, or carbon tetraiodide is used as a raw material for the single-crystalline spherical carbon nanoparticles and reduced with a platinum-supported single-crystalline spherical carbon nanoparticle reducing solution to produce the single-crystalline spherical carbon nanoparticles, lithium chloride, lithium bromide, or lithium iodide is produced as a byproduct. Due to their high solubility in ethereal solvents, these byproducts have the advantage of being easily separated from the platinum-supported single-crystalline spherical carbon nanoparticles by centrifugation.

[0073] 3. Application of Platinum-supported Single Crystal Spherical Carbon Nanoparticles The platinum-supported single-crystal spherical carbon nanoparticles produced by the production method of the present invention can be used as, for example, non-toxic catalysts, light-emitting elements, fluorescent luminescent materials, negative electrodes of lithium-ion batteries, electrode materials for solar cells, fuel cell catalysts, and materials for bonding semiconductor devices to substrates.

[0074] [Example] Hereinafter, the present invention will be further described with reference to examples, but the present invention is not limited to these examples.

[0075] (Preparation of samples for transmission electron microscopy (TEM) observation) The platinum-supported single-crystalline spherical carbon nanoparticles obtained in the Examples and Comparative Examples were dispersed in THF at a concentration of approximately 0.001% in a container. The container containing the resulting dispersion was placed in an argon atmosphere glove box, where the dispersion was dropwise added to a carbon support film and dried to prepare a sample for TEM observation.

[0076] (TEM observation) TEM observation of platinum-supported single-crystalline spherical carbon nanoparticles was performed using a transmission electron microscope JEM-2100 (manufactured by JEOL Ltd.). The aforementioned TEM observation sample was used. Observation conditions included an accelerating voltage of 200 kV and an observation magnification of 10,000 times or greater. The particle size was calculated based on the distance between the maximum peripheries of the platinum-supported single-crystalline spherical carbon nanoparticles observed by TEM. The average value (average particle size) of the results of the particle size measurements for 50 particles was calculated.

[0077] (Scanning transmission electron microscope and energy dispersive X-ray analyzer: STEM-EDS analysis) The element distribution and quantification of platinum-supported single-crystalline spherical carbon nanoparticles were determined by STEM-EDS analysis using an energy dispersive X-ray analyzer, a Centurio (manufactured by JEOL Ltd.), and a JEM-ARM200F (manufactured by JEOL Ltd.). Observation conditions were an accelerating voltage of 200 kV, an observation magnification of 50,000x or greater, and a beam diameter of 0.2 nm.

[0078] (Infrared (IR) absorption spectrum) The IR absorption spectrum of platinum-supported single-crystal spherical carbon nanoparticles was measured using the attenuated total reflectance (ATR) method using a Fourier transform infrared spectrophotometer FT / IR-6600 (manufactured by JASCO Corporation) and the ATR PRO470-H accessory of the FT / IR-6600. The measurement conditions were a resolution of 4.0 cm -1 The cumulative number of measurements was 128. The diamond prism used was a PKS-D1F wide-area (refractive index 2.4) and the incident angle was set to 45°. Infrared (IR) absorption spectra of the reducing solution (lithium metal dissolved in THF) and the platinum-supported single-crystalline spherical carbon nanoparticles produced in the Examples and Comparative Examples are shown as IR spectra. Waveform separation was performed using the spectrum analysis program included with the FT / IR-6600 control software, and curve fitting was performed to achieve a residual sum of squares of 0.05 or less.

[0079] (Confirmation of the formation of aromatic compound anions based on IR spectroscopy) As an example of an aromatic compound, the case of naphthalene is described. Metallic lithium is added to a THF solution in which naphthalene is dissolved, thereby generating a naphthalene anion as a reducing species, and its generation is confirmed by IR absorption spectroscopy. For the measurement sample, a reducing solution is dripped onto a potassium bromide (KBr) plate in an argon environment glove box, and after covering the dripping liquid with another KBr plate, it is held with MagHoldIR (manufactured by JASCO Engineering). After being taken out of the argon environment glove box, it is immediately measured using a Fourier transform infrared spectrophotometer FT / IR-6600 (manufactured by JASCO Corporation) by the transmission method. The measurement conditions are a resolution of 4.0 cm -1 , the cumulative number of times is set to 8 times.

[0080] (Confirmation of the formation of aromatic compound anions based on NMR spectroscopy) As an example of the formation of anions in aromatic compounds, naphthalene is used as an example. The formation of naphthalene anions can be determined by the chemical shift of nuclear magnetic resonance (NMR). 1 In H-NMR, hydrogen atoms bonded to carbon atoms of naphthalene are divided into H α and H β The two can be judged by the changes in the chemical shifts they represent. Since the naphthalene anion accepts the electrons generated by the dissolution of metallic lithium, it is necessary to evaluate the bonding state with the lithium cation. This can be done by 7 Li-NMR was used to evaluate the lithium cations. The sample was filled with a reducing solution in a quartz sample tube in an argon glove box, sealed, and then taken out. The sample was measured using a 400MHz NMR ECS-400 (manufactured by JEOL Ltd.). 7 Li-NMR spectrum measurements and hydrogen atoms 1 H-NMR spectrum measurements were performed at room temperature with a sample rotation frequency of 15 Hz. Since the state in the reduction reaction solution was measured directly, deuterated solvents were not used, and the software No-DNMR (Ver. 5) (manufactured by JEOL Ltd.) was used to perform the measurement using only the reduction solution. When THF was used as the solvent, the NMR spectrum measurements using this software were automatically extracted from the THF NMR spectrum and used as a reference. 1 H-NMR spectrum measurement. 7 In Li-NMR, lithium chloride (LiCl) is mixed in a reducing solution as a reference substance for measurement.

[0081] (fluorescence spectrum) The fluorescence spectrum of platinum-supported single-crystalline spherical carbon nanoparticles was measured using a spectrofluorometer FT-6500 (manufactured by JASCO Corporation). The sample solution used was the aforementioned sample solution for TEM observation. The sample solution, dispersed in THF, was placed in a quartz cell (optical path length: 1 cm) in an argon atmosphere glove box. The top was sealed and removed from the glove box for measurement. The measurement conditions were an excitation bandwidth of 3 nm, a fluorescence bandwidth of 3 nm, a response time of 0.1 seconds, a scan rate of 100 nm / min, and a data acquisition interval of 0.5 nm.

[0082] (roundness) The roundness, which is an index for evaluating the sphericity of platinum-supported single-crystalline spherical carbon nanoparticles, is calculated as follows. Regarding the roundness of platinum-supported single-crystalline spherical carbon nanoparticles, the image obtained by TEM observation is approximated as an ellipse using TEM imaging software iTEM (manufactured by Olympus Soft Imaging Solutions GmbH). Next, based on the analysis results of the TEM image analysis software, the major diameter (D), perimeter (Z), and area (S) of the projected image of the platinum-supported spherical carbon nanoparticles, i.e., the ellipse, are calculated. 4πS / Z is calculated using the perimeter (Z) and area (S) values. 2 As the roundness, the closer the roundness value is to 1, the closer the particle is to a sphere, and when the particle shape is a perfect sphere, the roundness is 1 at the maximum.

[0083] The average value of the major diameter (D) of the ellipse was calculated as the average particle diameter. The measurement was performed on 50 independent platinum-supported spherical carbon nanoparticles.

[0084] (X-ray diffraction (XRD)) XRD measurements were performed using a powder X-ray diffractometer, EMPYREAN (manufactured by Spectris Corporation, Malvern Panalytical Division). The measurement conditions were: a measurement range of 10 to 100° (2θ), a Cu counter cathode, a tube voltage of 45 kV, a tube current of 40 mA, and a scan rate of 0.013° / min.

[0085] Example 1 In Example 1, a THF solution containing metallic lithium dissolved in a naphthalene-dissolved THF solution (platinum-supported single-crystalline spherical carbon nanoparticle reduction solution (Solution A)) was used to reduce a THF solution containing carbon tetrachloride (CCl4), a raw material for single-crystalline spherical carbon nanoparticles (Single-crystalline spherical carbon nanoparticle raw material solution (Solution B)). This reduced solution produced single-crystalline spherical carbon nanoparticles. This solution was then continuously mixed with a THF solution containing chloroplatinic acid (IV) hexahydrate (Platinum raw material solution (Solution C)). This allowed the continuous production of platinum-supported single-crystalline spherical carbon nanoparticles without exposure to the atmosphere. Table 1 shows the components of Examples 1-1 to 1-4.

[0086] [Table 1]

[0087] The solvent used in Example 1 was ultra-dehydrated tetrahydrofuran (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) with a residual moisture content of less than 10 ppm. A platinum-supported single-crystalline spherical carbon nanoparticle reduction solution (Solution A), a single-crystalline spherical carbon nanoparticle raw material solution (Solution B), and a platinum raw material solution (Solution C) were prepared in an argon atmosphere glove box. Specifically, the platinum-supported single-crystalline spherical carbon nanoparticle reduction solution (Solution A) was prepared by dissolving metallic lithium to a concentration of 0.0515 mol / L in a THF solution containing naphthalene dissolved at a temperature of 20°C using a coated glass magnetic stirrer. The single-crystalline spherical carbon nanoparticle raw material solution (Solution B) was prepared by dissolving carbon tetrachloride, the single-crystalline spherical carbon nanoparticle raw material, in THF and stirring for at least 60 minutes using a coated glass magnetic stirrer. The platinum raw material solution (Solution C) was prepared by dissolving the platinum raw material, chloroplatinic acid (IV) hexahydrate, in THF and stirring for at least 60 minutes using a Teflon-coated magnetic stirrer. Regarding the chemical formulas or substances indicated by abbreviations in Table 1, CCl4 is carbon tetrachloride (manufactured by Kanto Chemical Co., Ltd.), Li is metallic lithium (manufactured by Kishida Chemical Co., Ltd.), and C 10 H8 is naphthalene (manufactured by Kanto Chemical Co., Ltd.), and H2PtCl6･6H2O is chloroplatinic acid (IV) hexahydrate (manufactured by Kishida Chemical Co., Ltd.).

[0088] The formation of naphthalene anions in solution A was confirmed by IR spectroscopy. Figure 1 c shows the result of subtracting the IR absorption spectrum of THF as a solvent from the IR absorption spectrum of a THF solution in which only naphthalene was dissolved. Figure 1 b shows the result of subtracting the IR absorption spectrum of the solvent, THF, from the IR absorption spectrum of the naphthalene THF solution in which metallic lithium was dissolved. Figure 1 a is to make Figure 1 c of 1508cm -1 The intensity of the IR absorption spectrum is related to Figure 1 b's 1508cm -1 The absorbance is consistent and corrected Figure 1 The intensity of the IR absorption spectrum of c, and from Figure 1 b The IR absorption spectrum is subtracted Figure 1 The results were obtained by measuring the IR absorption spectrum of c. Figure 1 1488cm confirmed in a -1 and 1183cm -1 The peak indicates that electrons generated by the dissolution of metallic lithium move to the LUMO of naphthalene to generate naphthalene anions.

[0089] The particle size of the produced single crystal spherical carbon particles will be distributed according to the change of the reducing power of liquid A. Therefore, it is preferable to confirm the reducing power. -1 The absorption peak of is steep and can be measured as a single peak. Therefore, the reducing power can be clearly judged by the decrease in the intensity of this absorption peak. If the reducing power decreases, a significant decrease in the intensity of this absorption peak can be confirmed.

[0090] When biphenyl or anthracene is used as an aromatic compound, the anions of biphenyl or anthracene in solution A are at 1160 cm -1 and 1175cm -1 The reduction in the reducing power of these aromatic compounds was also determined by the intensity of their respective absorption peaks.

[0091] Figure 2 The results are shown after 24 hours of preparation of a reduction solution of metallic lithium dissolved in naphthalene THF as solution A. 1 H-NMR spectrum. When only naphthalene is dissolved in THF solvent, two chemical shifts caused by hydrogen atoms show spectral peaks at 7.42 ppm and 7.82 ppm. These are caused by the H of neutral naphthalene molecules. β and H α In contrast, in the case of the naphthalene anion that accepts electrons generated by the dissolution of metallic lithium into the LUMO, two peaks at 5.9ppm and 6.1ppm and two peaks at 6.35ppm and 6.4ppm are confirmed. - ) and lithium cations (Li + ) can be bonded via the solvent THF (NPT･ - ･THF･Li + ) and direct bonding without THF (NPT･ - ･Li + It is believed that the two peaks at 6.35 ppm and 6.4 ppm and the two peaks at 5.9 ppm and 6.1 ppm reflect the states in which the naphthalene anion and the lithium cation are bonded by Coulomb force in the presence of THF.

[0092] Figure 3 is through 7Li-NMR measurements of a naphthalene THF reduction solution containing metallic lithium dissolved in solution A revealed peaks at 1 ppm and 10 ppm 12 hours after solution preparation. After 36 hours, the independent peak at 10 ppm shifted to 4 ppm, and after 100 hours, the peak shifted to 0 ppm. Regarding the reducing power of the reduction solution confirmed at 0 ppm after 100 hours, since platinum-supported carbon nanoparticles are rarely obtained even with the dark green color indicating the presence of naphthalene anions, even if naphthalene anions are present, the 0 ppm peak is judged to be a result of Coulombic bonding between the naphthalene anions solvated in THF and the lithium cations solvated in THF (THF･NPT･ - ･THF)･(THF･Li + When lithium chloride (LiCl) is dissolved in THF as a standard substance, the narrow and sharp peaks and the broadening of the peak width at the chemical shift of 0 ppm indicate a solution structure in which naphthalene anions exist around lithium cations.

[0093] Next, the prepared platinum-supported single-crystal spherical carbon nanoparticle reduction solution (Solution A), the single-crystal spherical carbon nanoparticle raw material solution (Solution B), and the platinum raw material solution (Solution C) were mixed using the fluid processing device described in Patent Document 6 of the applicant of the present application. Here, the fluid processing device described in Patent Document 6 refers to the same publication. Figure 1 The apparatus described in (B) utilizes disks with annular openings d20 and d30 in the second and third introduction sections, i.e., concentric ring-shaped disks surrounding the central opening of processing surface 2. Specifically, while a platinum-supported single-crystalline spherical carbon nanoparticle reduction solution (Solution A) is introduced between processing surfaces 1 and 2 from the first introduction section d1 and the processing section 10 is operated at a rotational speed of 700 to 5000 rpm, a single-crystalline spherical carbon nanoparticle raw material solution (Solution B) is introduced between processing surfaces 1 and 2 from the second introduction section d2. The platinum-supported single-crystalline spherical carbon nanoparticle reduction solution and the single-crystalline spherical carbon nanoparticle raw material solution are mixed in a thin film fluid, resulting in the precipitation of single-crystalline spherical carbon nanoparticles between processing surfaces 1 and 2. Subsequently, a platinum raw material solution (Solution C) is introduced between processing surfaces 1 and 2 from the third introduction section d3 and mixed with the mixed fluid containing single-crystalline spherical carbon nanoparticles in the thin film fluid. Platinum particles are supported on the surfaces of the single-crystalline spherical carbon nanoparticles, and a discharge liquid containing the platinum-supported single-crystalline spherical carbon nanoparticles (hereinafter referred to as a dispersion liquid of platinum-supported single-crystalline spherical carbon nanoparticles) is discharged from between processing surfaces 1 and 2 of the fluid treatment device. The discharged dispersion liquid of platinum-supported single-crystalline spherical carbon nanoparticles is recovered in a beaker via a container.

[0094] Table 2 shows the operating conditions of the fluid processing device. The inlet temperatures (liquid delivery temperatures) and inlet pressures (liquid delivery pressures) of Liquids A, B, and C shown in Table 2 were measured using thermometers and pressure gauges installed in the sealed inlet passages (first inlet section d1, second inlet section d2, and third inlet section d3) connecting processing surfaces 1 and 2. The inlet temperature of Liquid A shown in Table 2 is the actual temperature of Liquid A at the inlet pressure in first inlet section d1. Similarly, the inlet temperature of Liquid B is the actual temperature of Liquid B at the inlet pressure in second inlet section d2, and the inlet temperature of Liquid C is the actual temperature of Liquid C at the inlet pressure in third inlet section d3. The inlet temperature was 20°C, and the inlet pressure was 0.1 MPaG or less.

[0095] [Table 2]

[0096] A wet cake sample was prepared from a dispersion of platinum-supported single-crystalline spherical carbon nanoparticles discharged from the fluid handling device and recovered in a beaker. The preparation method followed conventional procedures. The discharged dispersion of platinum-supported single-crystalline spherical carbon nanoparticles was recovered, and the platinum-supported single-crystalline spherical carbon nanoparticles were allowed to settle from the recovered liquid by centrifugation (30190G for 2 hours), separating the supernatant. Ultrasonic cleaning and sedimentation in THF were then repeated, and the resulting platinum-supported single-crystalline spherical carbon nanoparticles were dried at -0.10 MPaG at 25°C for 20 hours to form a dry powder.

[0097] Figure 4 The TEM observation image of the platinum-supported single-crystal spherical carbon nanoparticles produced in Example 1-1 is shown. The same result was confirmed for the platinum-supported single-crystal spherical carbon nanoparticles of Examples 1-2 to 1-4. Since the lattice fringes were observed in one direction, it was confirmed that the single-crystal spherical carbon nanoparticles were single crystals. As an example of the lattice spacing of single-crystal spherical carbon nanoparticles, the length measurement value of 1580pm of the 5-lattice plane spacing was divided by 5 to obtain 316pm. In addition, Figure 5 As shown in FIG, an example of the lattice plane spacing of the supported platinum particles is 231 pm, which is obtained by dividing the measured length value of 1155 pm of the lattice plane spacing by 5. These values ​​are respectively attributed to the carbon (003) plane and the platinum (111) plane.

[0098] Figure 6The results of superimposing the STEM observation images of the platinum-supported single-crystalline spherical carbon nanoparticles produced in Example 1-2 and the detection intensity of the platinum particles using STEM-EDS line analysis are shown. High platinum intensity was detected on the surface side of the platinum-supported spherical carbon nanoparticles, confirming that platinum particles were supported on the surface of the single-crystalline spherical carbon nanoparticles. Furthermore, platinum was also detected within the platinum-supported single-crystalline spherical carbon nanoparticles. This indicates that platinum particles of approximately 1 nm, which are finer than the approximately 3 nm particle size typically seen in platinum-supported carbon nanoparticles, are adsorbed and coated on the surface of the single-crystalline spherical carbon nanoparticles. This result indicates that, unlike conventional results in which carbon powders supporting platinum particles are coated with platinum particles and uncovered areas can be discerned, the platinum particles are more uniformly supported on the single-crystalline spherical carbon nanoparticles. This uniform support of platinum particles on the surface of the single-crystalline spherical carbon nanoparticles indicates that the single-crystalline carbon nanoparticles produced by the present invention are spherical and do not represent a state in which platinum particles are supported on agglomerated single-crystalline carbon nanoparticles.

[0099] (CH bond) Figure 7 The IR spectrum of the platinum-supported single-crystal spherical carbon nanoparticles of Example 1-1 was measured at a wave number of 2800 cm -1 ~3000cm -1 The result of the waveform separation in the region of 2856cm -1 and 2871cm -1 The absorption of 2932cm -1 and 2957cm -1 The absorption peaks are attributed to the CH3 and CH2 bonds of the C-H bonds, confirming that the platinum-supported single-crystalline spherical carbon nanoparticles are hydrogenated. This was also confirmed in Examples 1-2, 1-3, and 1-4. The values ​​in parentheses represent relative area ratios.

[0100] Figure 8 The IR spectrum of the platinum-supported single-crystal spherical carbon nanoparticles of Example 1-1 was measured with a wave number of 900 cm -1 ~1900cm -1 The peak wave number of each band after waveform separation is shown, and the relative area ratio is shown in brackets.

[0101] (CO key) Figure 8 The IR spectrum was divided into 8 parts by waveform separation, 1000 cm -1 ~1100cm -1 The absorption in the wave number region of 1056cm is attributed to the CO bond. -1The ratio of (band 8) to the total area (ratio of CO bonds) is 12.2%. The CO bond ratio is preferably 2% or more and 15% or less. This is because if it is less than 2%, the platinum-supported single-crystalline spherical carbon nanoparticles are difficult to disperse in an aqueous solution. If it exceeds 15%, the circularity of the platinum-supported single-crystalline spherical carbon nanoparticles falls below 0.80, which greatly deviates from sphericity and may result in a decrease in sphericity.

[0102] The C-O bonds of platinum-supported single-crystalline spherical carbon nanoparticles can be produced by a reduction reaction in super-dehydrated THF, where the residual water content is controlled to 10 ppm or less. The surface of the platinum-supported single-crystalline spherical carbon nanoparticles is formed by the supported platinum particles, C-O bonds, and C-H bonds, making them easily dispersible in organic solvents.

[0103] (CN key) The CN bond is generated by the reaction with the outermost surface of the graphene layer not protected by oxygen due to exposure to the atmospheric environment during the cleaning and recovery process of the platinum-supported single-crystal spherical carbon nanoparticles. The presence of the CN bond also indicates the termination of the bond defects of the single-crystal spherical carbon particles caused by nitrogen. Figure 8 In the IR spectrum, the CN bond is -1 ~1400cm -1 The wave number region has absorption, so it corresponds to the peak wave number 1371cm -1 Band 5 has a relative area ratio (ratio of CN bonds) of 6.0%. Because CN bonds, along with CO bonds, have the effect of terminating defects that break bonds between carbon atoms in the graphene layer, the CN bond ratio is preferably 10% or less. If CO bonds terminate carbon atom bond defects, the CN bonds may not be detected.

[0104] Figure 7 The CH bonds of the platinum-supported single-crystal spherical carbon nanoparticles confirmed in the IR spectrum can make the surface of the single-crystal spherical carbon nanoparticles hydrophobic, so the platinum-supported single-crystal spherical carbon nanoparticles can be well dispersed in organic solvents. Figure 8 The results confirmed that the coexistence of CO bonds enabled dispersibility in aqueous solvents.

[0105] It is known that in the case of C=C bonds, the -1 to 1690cm -1 See absorption, therefore Figure 8 The IR spectrum of 1638 cm-1, which shows the maximum intensity, was confirmed by waveform separation. -1 Band 2 can be considered to reflect the bonding state of the carbon graphite structure of the platinum-supported single-crystal spherical carbon nanoparticles.

[0106] Figure 9 The fluorescence spectrum of the platinum-supported single-crystalline spherical carbon nanoparticles of Example 1-2, confirmed at an excitation wavelength of 240 nm, was shown. The fluorescence peak wavelength was confirmed to be 420 nm, and visible fluorescence was obtained by ultraviolet light of less than 300 nm.

[0107] The change in the fluorescence peak wavelength of platinum-supported single-crystalline spherical carbon nanoparticles is explained by the quantum effect (A), one of the three mechanisms (A) to (C). Specifically, it is believed that the fluorescence peak wavelength of platinum-supported single-crystalline spherical carbon nanoparticles shifts toward shorter wavelengths due to an increase in the band gap as the particle size decreases, resulting in a shift in the fluorescence peak wavelength due to the quantum effect (A). Furthermore, the platinum-supported single-crystalline spherical carbon nanoparticles of the present invention are not surface-modified with alkyl or amino groups, and thus do not involve the surface modification mechanism (B) of the three mechanisms described above. Therefore, it is believed that fluorescence is generated by a synergistic effect between the mechanism (C) via oxygen, which is based on the bonding of oxygen to the single-crystalline spherical carbon particles, and the quantum effect (A).

[0108] Figure 10 The XRD patterns of the platinum-supported single-crystal spherical carbon particles of Examples 1 to 4 are shown. Graphite crystals have a structure in which graphene layers are stacked in the c-axis direction. The graphene layers are composed of sp 2 The C=C bonds composed of carbon atoms of hybrid orbitals form planar layers, and as a crystal system, in hexagonal graphite, simple lattices and rhombohedral lattices can be formed as space lattices. The peaks with diffraction angles 2θ of 42.2° and 44.6° appear through the simple lattice of the hexagonal structure, and the peak with a diffraction angle 2θ of 43.3° appears through the rhombohedral lattice. In single-crystal spherical carbon nanoparticles with a hexagonal structure, when the space lattice is a simple lattice, if the two-layer graphene layer is set as the A layer and the B layer, it means that a stacked structure such as ABABAB... is formed. In the rhombohedral lattice, if the three-layer graphene layer is set as the A layer, the B layer, and the C layer, it means that they form a stacked structure such as ABCABCABC... Therefore Figure 10 The presence of a diffraction peak at about 43° in 2θ obtained in the scattering spectrum indicates that the spatial lattice of the single-crystal spherical carbon nanoparticles is a rhombohedral lattice.

[0109] Table 3 shows the average particle size, average circularity, average lattice plane spacing of the graphene layer of the carbon particles, average lattice spacing of the platinum particles, the ratio of CO bonds obtained in the IR spectrum, and the fluorescence peak wavelength measured at an excitation wavelength of 240 nm of the platinum-supported single-crystalline spherical carbon nanoparticles of Examples 1-1 to 1-4.

[0110] [Table 3]

[0111] Comparative Example 1 Comparative Example 1 had the same components as Example 1 shown in Table 1, but the disc rotation speed was reduced to 600 rpm and 500 rpm, as shown in Table 4, to produce platinum-supported single-crystalline spherical carbon nanoparticles. Table 5 shows the results of the resulting platinum-supported single-crystalline spherical carbon nanoparticles. No changes in the crystal structure were observed due to the disc rotation speed being lowered to less than 700 rpm.

[0112] [Table 4]

[0113] [Table 5]

[0114] Example 2 Example 2 shows the results of platinum-supported single-crystalline spherical carbon nanoparticles produced using a platinum-supported single-crystalline spherical carbon nanoparticle reduction solution (Solution A) at 5°C and a disc rotation speed of 5000 rpm to 2100 rpm. The compositions of the platinum-supported single-crystalline spherical carbon nanoparticle reduction solution (Solution A) and the single-crystalline spherical carbon nanoparticle raw material solution (Solution B) were the same as those in Example 1, and production was carried out under the conditions shown in Table 1. Table 6 shows the production conditions for Example 2, and the results of the resulting platinum-supported single-crystalline spherical carbon nanoparticles are shown in Table 7. In the platinum-supported single-crystalline spherical carbon nanoparticles produced in Example 2, the average particle size decreased with increasing disc rotation speed.

[0115] [Table 6]

[0116] [Table 7]

[0117] Comparative Example 2 Comparative Example 2 had the same components as Example 1 shown in Table 1. However, as shown in Table 8, the disk rotation speed was reduced to 700 rpm and 500 rpm, and the temperature of the platinum-supported single-crystalline spherical carbon nanoparticle reducing solution (Solution A) was set at 5°C to produce platinum-supported single-crystalline spherical carbon nanoparticles. Table 9 shows the results of the produced platinum-supported single-crystalline spherical carbon nanoparticles. The average circularity of the platinum-supported single-crystalline spherical carbon nanoparticles produced by reducing the disk rotation speed to 700 rpm and 500 rpm and setting the solution A temperature to 5°C was less than 0.8.

[0118] [Table 8]

[0119] [Table 9]

[0120] Example 3 The compositions of Solution A, Solution B, and Solution C in Example 3 are shown in Table 10. Because the four chlorine atoms in carbon tetrachloride are bonded to carbon atoms, in order to dissociate all four chlorine atoms and reduce them to carbon particles, the ratio of metallic lithium and naphthalene in the reducing solution (Solution A) for platinum-supported single-crystalline spherical carbon nanoparticles must be 4 times the molar ratio per 1 mol of carbon tetrachloride. The compositions in Examples 1 and 2 were designed to relatively reduce the naphthalene concentration in the reaction solution during the production of platinum-supported single-crystalline spherical carbon nanoparticles. Instead of setting the molar ratio of metallic lithium to naphthalene in the reducing solution to 1 / 8 molar ratio per 1 mol of carbon tetrachloride, the flow rate of Solution A during production was increased to 8 times the molar ratio. In Example 3, on the other hand, the ratio of metallic lithium and naphthalene in the reducing solution to 4 times the molar ratio per 1 mol of carbon tetrachloride was adjusted to a 1:1 ratio between the single-crystalline spherical carbon nanoparticle raw material solution (Solution B) and the platinum-supported single-crystalline spherical carbon nanoparticle reducing solution (Solution A), and the flow rates of Solution A and Solution B were varied to produce platinum-supported single-crystalline spherical carbon nanoparticles. Table 10 shows the production components of platinum-supported single-crystal spherical carbon nanoparticles, and Table 11 shows the production conditions.

[0121] [Table 10]

[0122] [Table 11]

[0123] Figure 11 The STEM observation image and element distribution obtained by STEM-EDS of the platinum-supported single-crystalline spherical carbon nanoparticles produced in Example 3-1 are shown. These results confirm that the platinum particles are uniformly supported on the platinum-supported single-crystalline spherical carbon nanoparticles. This is different from the case where the platinum particles are randomly supported on the single-crystalline spherical carbon nanoparticles when the single-crystalline spherical carbon particle diameter is approximately 15 nm, as confirmed in Example 1-1. In Examples 3-2 and 3-3, it was also confirmed that the platinum particles are similarly uniformly supported on the single-crystalline spherical carbon nanoparticles.

[0124] According to the present invention, by producing single-crystalline spherical carbon nanoparticles in a solution and continuously producing platinum particles, the platinum particles can be loaded on the single-crystalline spherical carbon nanoparticles as nanoparticles of about 1 nm, thereby covering the surface of the single-crystalline spherical carbon nanoparticles with platinum particles using less platinum raw material. Therefore, it is believed that this is also useful from the perspective of precious metal resource protection.

[0125] Table 12 shows the results of the obtained platinum-supported single-crystal spherical carbon nanoparticles.

[0126] [Table 12]

[0127] [Industrial Applicability] According to the manufacturing method of the present invention, platinum-supported single-crystal spherical carbon nanoparticles can be manufactured. The manufactured platinum-supported single-crystal spherical carbon nanoparticles do not have the toxicity to organisms that compound semiconductors formed from cadmium, selenium, tellurium, etc. have, and therefore have the advantage of not requiring recovery after use as catalysts or electrode materials. Furthermore, due to their spherical shape, they can be filled with high-density electrode materials for solar cells or secondary ion batteries, and because they support platinum particles, they can be used as negative electrodes for lithium-ion batteries or electrode materials for solar cells to improve the conductivity of the carbon nanoparticles in contact with each other.

Claims

1. A method for producing platinum-supported single-crystalline spherical carbon nanoparticles, wherein the platinum-supported single-crystalline spherical carbon nanoparticles have platinum particles supported on the surface of the single-crystalline spherical carbon nanoparticles, wherein: The manufacturing method comprises: The single-crystal spherical carbon nanoparticle raw material solution containing a halogenated carbon and a platinum-supported single-crystal spherical carbon nanoparticle reducing solution containing anions of the aromatic compound generated from lithium, sodium or potassium and the aromatic compound are mixed to produce the single-crystal spherical carbon nanoparticles. Then, a platinum raw material solution containing a platinum halide is continuously added to the obtained mixture to produce platinum-supported single-crystal spherical carbon nanoparticles.

2. The manufacturing method according to claim 1, wherein Using the perimeter Z and area S of the projected image of the single-crystal spherical carbon nanoparticle observed by a transmission electron microscope, the mathematical formula: 4πS / Z 2 The calculated average value of the circularity was 0.80 or more.

3. The manufacturing method according to claim 1 or 2, wherein: The average particle size of the single crystal spherical carbon nanoparticles is 1 nm to 200 nm.

4. The production method according to any one of claims 1 to 3, wherein The single-crystal spherical carbon nanoparticle raw material solution and the platinum-supported single-crystal spherical carbon nanoparticle reduction solution are mixed using the following apparatus to produce single-crystal spherical carbon nanoparticles, Then, a platinum raw material solution containing platinum halide is continuously added to the obtained mixture to produce platinum-supported single-crystal spherical carbon nanoparticles. The device comprises: a fluid pressure applying mechanism for applying pressure to a fluid to be processed; at least two processing parts, a first processing part and a second processing part, wherein the second processing part can be relatively close to or separated from the first processing part; and a rotation driving mechanism for rotating the first processing part and the second processing part relative to each other. At least two processing surfaces, a first processing surface and a second processing surface, are provided at positions facing each other in each of the processing parts. Each of the processing surfaces constitutes a part of a sealed flow path for a pressurized processed fluid to flow. Between the two processing surfaces, two or more processed fluids, at least one of which contains a reactant, are mixed and reacted. In the first processing part and the second processing part, at least the second processing part has a pressure-bearing surface, and at least a part of the pressure-bearing surface is composed of the second processing surface. The pressure-bearing surface is subjected to the pressure applied by the fluid pressure applying mechanism to the processed fluid, thereby generating a force that moves the second processing surface in a direction away from the first processing surface, thereby being able to approach or separate. By allowing the processed fluid to be pressurized to pass between the relatively rotating first processing surface and the second processing surface, the processed fluid forms a thin film fluid, and further has another inlet path independent of the flow path between each processing surface for the processed fluid to flow. At least either one of the first processing surface and the second processing surface has at least one opening connected to the another inlet path. By introducing at least one processed fluid sent from the another inlet path between the two processing surfaces, the reactant contained in at least any one of the processed fluids and the processed fluid different from the processed fluid are mixed in the thin film fluid.

5. The manufacturing method according to claim 4, wherein: The opening is provided at a position downstream of a point where the flow of the fluid to be processed passing between the two processing surfaces becomes laminar flow.

6. The production method according to any one of claims 1 to 5, wherein The molar ratio of the lithium, sodium or potassium to the carbon halide is 7:1 to 4:

1.

7. The production method according to any one of claims 1 to 6, wherein The aromatic compound is at least one selected from the group consisting of biphenyl, naphthalene, 1,2-dihydronaphthalene, anthracene, phenanthrene, and pyrene.

8. The manufacturing method according to claim 7, wherein: When the aromatic compound is biphenyl, naphthalene or anthracene, in the IR absorption spectrum of the platinum-supported single-crystal spherical carbon nanoparticle reduction solution, the peak at 1200 cm -1 ~1100cm -1 The wavenumber range shows the absorption peak.

9. The production method according to any one of claims 1 to 8, wherein In the case where the aromatic compound is biphenyl, naphthalene or anthracene, in the platinum-supported single crystal spherical carbon nanoparticle reduction solution 1 The H-NMR spectrum showed at least four peaks due to chemical shifts from 5.5 ppm to 6.5 ppm.

10. The production method according to any one of claims 1 to 9, wherein In the case where the aromatic compound is biphenyl, naphthalene or anthracene, in the platinum-supported single crystal spherical carbon nanoparticle reduction solution 7 In the Li-NMR spectrum, a peak due to chemical shift appears at 2 ppm or higher.

11. The production method according to any one of claims 1 to 10, wherein The solvent contained in the platinum-supported single-crystal spherical carbon nanoparticle reduction solution is tetrahydrofuran, 2-methyltetrahydrofuran, and dimethoxyethane, each having a residual water content of 10 ppm or less.

12. The production method according to any one of claims 1 to 11, wherein The solvent contained in the platinum-supported single-crystal spherical carbon nanoparticle reduction solution is tetrahydrofuran containing a phenolic polymerization inhibitor, a residual water content of 10 ppm or less, and a residual oxygen concentration of less than 0.1 ppm.

13. The production method according to any one of claims 1 to 12, wherein The solvent contained in the raw material liquid of single-crystal spherical carbon nanoparticles is tetrahydrofuran, 2-methyltetrahydrofuran or dimethoxyethane, wherein the residual water content is less than 10 ppm and the residual oxygen concentration is less than 0.1 ppm.

14. The production method according to any one of claims 1 to 13, wherein The halocarbon is carbon tetrachloride, carbon tetrabromide or carbon tetraiodide.

15. The production method according to any one of claims 1 to 14, wherein The platinum halide is hexachloroplatinic acid (IV) hexahydrate or platinum (IV) chloride.

16. The production method according to any one of claims 1 to 15, wherein The single crystal spherical carbon nanoparticles are hexagonal crystals.

17. The production method according to any one of claims 1 to 16, wherein The platinum-supported single-crystal spherical carbon nanoparticles have an IR absorption spectrum at 2800 cm -1 ~3000cm -1 The wavenumber range shows the absorption peak, for 900cm -1 ~1900cm -1 The 1000 cm -1 ~1100cm -1 The absorption peak area relative to 900 cm -1 ~1900cm -1 The total area of ​​the wavenumber range is less than 15%.

18. The production method according to any one of claims 1 to 17, wherein The platinum-supported single-crystal spherical carbon nanoparticles have an IR absorption spectrum of 900 cm -1 ~1900cm -1 The 1300 cm -1 ~1400cm -1 The absorption peak area relative to 900 cm -1 ~1900cm -1 The total area of ​​the wavenumber range is less than 10%.

19. The production method according to any one of claims 1 to 18, wherein In the fluorescence spectrum, the platinum-supported single-crystal spherical carbon nanoparticles generate maximum fluorescence in a wavelength range of 400 nm to 500 nm with an excitation wavelength of 240 nm.

20. A platinum-supported single-crystal spherical carbon nanoparticle, wherein: Platinum is supported on the surface of single-crystal spherical carbon nanoparticles having an average particle diameter of 1 nm to 30 nm.

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