Carbon material, catalyst, dispersion liquid, electrode, battery, and electrolysis device

Abstract

A carbon material which contains at least carbon, nitrogen and bromine as constituent elements, has a bromine content of 50-100,000 ppm by mass as measured by combustion ion chromatography, and satisfies 0.005 < = Nxps / Cxps < = 0.300, the number Cxps of carbon atoms and the number Nxps of nitrogen atoms as measured by X-ray photoelectron spectroscopy.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to a carbon material, a catalyst, a dispersion liquid, an electrode, a battery, and an electrolytic device. BACKGROUND

[0002] A carbon material is used for a wide range of uses due to characteristics such as high electrical conductivity, high thermal conductivity, low thermal expansion, light weight, heat resistance, and the like. In recent years, a nitrogen-containing carbon material is being studied for use as a positive electrode catalyst (oxygen reduction catalyst) for a fuel cell and / or an air cell (see Patent Literature 1). In addition, a nitrogen-containing carbon material sometimes has carbon dioxide reduction activity and / or nitrogen reduction activity, and is also attracting attention as a cathode catalyst (carbon dioxide reduction catalyst or nitrogen reduction catalyst) in an electrolytic device (see Non-Patent Literature 1 and Non-Patent Literature 2).

[0003] Prior Art Documents

[0004] Patent Literature

[0005] Patent Literature 1: Japanese Patent Application Publication No. 2012-101155

[0006] Patent Literature 2: International Publication No. 2021 / 220495

[0007] Non-Patent Literature

[0008] Non-Patent Literature 1: Angew. Chem. Int. Ed., 2015, 54, 10758-10762

[0009] Non-Patent Literature 2: Nature Communications, 2019, 10, 341-348 SUMMARY

[0010] Problems to be Solved by the Invention

[0011] An object of one aspect of the present disclosure is to provide a novel carbon material that can be used for an electrode catalyst.

[0012] Means for Solving the Problems

[0013] Several aspects of the present disclosure provide the following [1] to

[21] . [1]

[0015] A carbon material containing at least carbon, nitrogen, and bromine as constituent elements,

[0016] a bromine content of 50 to 100,000 mass ppm as measured by combustion ion chromatography,

[0017] an atomic number C of carbon atoms quantified by X-ray photoelectron spectroscopy xps and an atomic number N of nitrogen atomsxps satisfies 0.005 ≤ N xps / C xps ≤ 0.300. [2]

[0019] The carbon material according to [1], which contains at least one metal element selected from the group consisting of Fe, Co, Ni, Cu, and Zn as a constituent element. [3]

[0021] The carbon material according to [2], wherein the total content of the metal element determined by inductively coupled plasma emission spectrometry is 0.005 to 20 mass%. [4]

[0023] The carbon material according to [2] or [3], wherein the content of the Fe element determined by inductively coupled plasma emission spectrometry is 1 to 60,000 mass ppm. [5]

[0025] The carbon material according to [2], wherein the content of the Zn element determined by inductively coupled plasma emission spectrometry is 1 to 60,000 mass ppm. [6]

[0027] The carbon material according to any one of [1] to [5], wherein, in a N1s spectrum determined by X-ray photoelectron spectroscopy, the peak intensity I1 at 398.5 ± 0.5 eV and the peak intensity I2 at 401.2 ± 0.5 eV satisfy 0.7 ≤ I2 / I1 ≤ 3.0. [7]

[0029] The carbon material according to any one of [1] to [6], wherein the number of atoms of carbon atoms C CHN and the number of atoms of nitrogen atoms N CHN satisfies 0.005 ≤ N CHN / C CHN ≤ 0.300. [8]

[0031] The carbon material according to any one of [1] to [7], which is a powdery material having porosity. [9]

[0033] The carbon material according to [8], wherein the specific surface area determined by the single-point BET method is 100 to 2,000 m 2 / g.

[10]

[0035] The carbon material according to [8] or [9] has micropores with a pore diameter of less than 2 nm,

[0036] The total volume of the micropores is 0.03 to 3.00 cm 3 / g as measured by a nitrogen adsorption method.

[11]

[0038] The carbon material according to any one of [8] to

[10] has mesopores with a pore diameter of 2 to 50 nm,

[0039] The total volume of the mesopores is 0.3 to 4.0 cm 3 / g as measured by a nitrogen adsorption method.

[12]

[0041] The carbon material according to any one of [1] to

[11] , wherein the electrical conductivity is 0.01 to 50 S / cm.

[13]

[0043] The carbon material according to any one of [1] to

[12] is a sintered product of a raw material containing a phthalocyanine compound having bromine as a substituent.

[14]

[0045] The carbon material according to

[13] , wherein the phthalocyanine compound contains Zn as a central metal.

[15]

[0047] The carbon material according to

[13] or

[14] , wherein the raw material further contains a compound containing at least one metal element selected from the group consisting of Fe, Co, Ni, Cu, Al, and Zn.

[16]

[0049] A catalyst containing the carbon material according to any one of [1] to

[15] .

[17]

[0051] A dispersion liquid containing the carbon material according to any one of [1] to

[15] and a dispersion medium of the carbon material.

[18]

[0053] The dispersion liquid according to

[17] contains a high-molecular electrolyte.

[19]

[0055] An electrode provided with an electrode catalyst layer containing the carbon material according to any one of [1] to

[15] .

[20]

[0057] A battery provided with the electrode according to

[19] .

[21]

[0059] An electrolytic device provided with the electrode of

[19] .

[0060] Effects of the Invention

[0061] According to one aspect of the present disclosure, it is possible to provide a novel carbon material that can be used for an electrode catalyst. DETAILED DESCRIPTION

[0062] In the present specification, a numerical range represented by "~" indicates a range in which the values recited before and after "~" are respectively included as the minimum value and the maximum value. In addition, except for the case where it is specifically indicated, the units of the values recited before and after "~" are the same. In the numerical range recited in stages in the present specification, the upper limit value or the lower limit value of a certain stage numerical range can be replaced with the upper limit value or the lower limit value of the numerical range of another stage. In addition, in the numerical range recited in the present specification, the upper limit value or the lower limit value of the numerical range can be replaced with the value shown in the examples (experimental examples). In addition, the upper limit value and the lower limit value recited separately can be arbitrarily combined.

[0063] Hereinafter, a preferred embodiment of the present disclosure will be described. However, the present disclosure is not limited by any of the following examples.

[0064] (Carbon material)

[0065] One embodiment of the present disclosure is a carbon material containing at least carbon (C), nitrogen (N), and bromine (Br) as constituent elements, having a bromine content of 50 to 100,000 mass ppm measured by combustion ion chromatography (CIC), and having a ratio of the number of carbon atoms C xps to the number of nitrogen atoms N xps satisfying 0.005 ≤ N xps / C xps ≤ 0.300. The specific measurement method of the bromine content and the ratio of the elements N xps / C xps is described in the examples (experimental examples). Hereinafter, in the present specification, N xps / C xps refers to the ratio of the number of carbon atoms C xps to the number of nitrogen atoms N xps quantified by XPS.

[0066] The carbon material described above exhibits excellent oxygen reduction activity, and thus can be used as a catalyst for a reduction reaction of oxygen (oxygen reduction catalyst), such as a positive electrode catalyst for a fuel cell, an air cell, and the like, and / or a cathode catalyst for an oxygen electrolysis device, and the like. The carbon material described above also has a tendency to exhibit carbon dioxide reduction activity and nitrogen reduction activity. Thus, the carbon material described above can also be used as a catalyst for a reduction reaction of carbon dioxide (carbon dioxide reduction catalyst) and a catalyst for a reduction reaction of nitrogen (nitrogen reduction catalyst). As specific uses, a cathode catalyst for a carbon dioxide electrolysis device and a nitrogen electrolysis device can be exemplified. The oxygen reduction activity, the carbon dioxide reduction activity, and the nitrogen reduction activity of the carbon material can be confirmed by the method described in the examples (experimental examples).

[0067] The carbon material is mainly a material containing carbon (C), and the content of carbon in the carbon material is 60% by mass or more. The content of carbon in the carbon material can be determined by CHN elemental analysis using a combustion method. The content of carbon in the carbon material can be 70% by mass or more or 80% by mass or more.

[0068] From the viewpoint of easily obtaining more excellent oxygen reduction activity, the content of bromine described above can be 500 ppm by mass or more or 2000 ppm by mass or more, and can be 50000 ppm by mass or less or 20000 ppm by mass or less.

[0069] From the viewpoint of easily obtaining more excellent oxygen reduction activity, the content of nitrogen described above can be 0.010% by mass or more or 0.050% by mass or more, and can be 0.220% by mass or less or 0.140% by mass or less. xps / C xps may be 0.010 or more or 0.050 or more, and can be 0.220 or less or 0.140 or less.

[0070] In the N 1s spectrum described above measured by XPS, the peak intensity I1 at 398.5 ± 0.5 eV and the peak intensity I2 at 401.2 ± 0.5 eV can satisfy 0.7 ≤ I2 / I1 ≤ 3.0. In this case, there is a tendency to obtain more excellent oxygen reduction activity. The reason is presumed as follows. First, in the N 1s spectrum described above, the peak at 398.5 ± 0.5 eV is attributed to pyridine-type nitrogen, and the peak at 401.2 ± 0.5 eV is attributed to quaternary ammonium-type nitrogen. Thus, the intensity ratio of the two peaks corresponds to the ratio of the amount of quaternary ammonium-type nitrogen to the amount of pyridine-type nitrogen contained in the carbon material. It is presumed that nitrogen in the carbon material forms active sites for oxygen reduction, and as a result, it is presumed that when the amount of pyridine-type nitrogen and the amount of quaternary ammonium-type nitrogen are within a prescribed range, the balance of the amount of active sites is good, and more excellent oxygen reduction activity can be obtained. From the viewpoint of obtaining further excellent oxygen reduction activity, the peak intensity ratio I2 / I1 described above can be 1.0 or more or 1.4 or more, and can be 2.0 or less or 1.5 or less.

[0071] From the viewpoint of further improving the catalytic activity and the conductivity, the atomic number of carbon atoms C CHN and the atomic number of nitrogen atoms N CHN may satisfy 0.005 ≤ N CHN / C CHN ≤ 0.300. Hereinafter in the present specification, N CHN / C CHN means the ratio of the atomic number of carbon atoms C CHN to the atomic number of nitrogen atoms N CHN quantified by CHN elemental analysis.

[0072] From the viewpoint of further improving the catalytic activity, N CHN / C CHN may be 0.05 or more, or 0.08 or more. From the viewpoint of the conductivity, N CHN / C CHN may be 0.2 or less, or 0.16 or less.

[0073] In the carbon material, the ratio of N XPS / C XPS to N CHN / C CHN is not particularly limited, and for example, [N XPS / C XPS ] / [N CHN / C CHN ] can be 0.7 or more, or 0.8 or more. When [N XPS / C XPS ] / [N CHN / C CHN ] is within the above range, the activity of the catalyst is more excellent. This is presumably due to the following reasons. In general, it is known that the detection depth in XPS measurement is about 10 nm from the surface of a sample. That is, in XPS measurement, atoms present in a region (hereinafter referred to as "surface layer") from the surface of the sample to a depth of about 10 nm are measured. Therefore, [N XPS / C XPS ] / [N CHN / C CHN ] of 0.7 or more indicates that a large number of nitrogen atoms exist in the surface layer of the sample. Since nitrogen atoms are also active sites, it is presumed that by the large number of nitrogen atoms existing in the surface layer of the sample, the activity of the catalyst is more excellent.

[0074] The carbon material can further contain a metal element. As the metal element, Al (aluminum), Ti (titanium), V (vanadium), Cr (chromium), Mn (manganese), Fe (iron), Co (cobalt), Ni (nickel), Cu (copper), Zn (zinc), Nb (niobium), Mo (molybdenum), Ru (ruthenium), Rh (rhodium), Pd (palladium), Ag (silver), Hf (hafnium), Ta (tantalum), W (tungsten), Re (rhenium), Os (osmium), Ir (iridium), Pt (platinum), Ga (gallium), Au (gold), and the like can be exemplified. The metal element contained in the carbon material can be one or two or more. The above metal element can be, for example, an element derived from a central metal contained in a phthalocyanine compound that is a raw material of the carbon material.

[0075] In one embodiment, the carbon material can contain Zn as a constituent element. In this case, there is a tendency that the oxygen reduction activity, the carbon dioxide reduction activity, and the nitrogen reduction activity are more excellent.

[0076] In another embodiment, the carbon material can contain at least one metal element selected from the group consisting of Fe, Co, Ni, Cu, and Zn (hereinafter referred to as "metal element M1") as a constituent element. These metal elements are elements that promote adsorption of a gas (oxygen, carbon dioxide, nitrogen) to the surface of the carbon material. In the case where the carbon material contains the above metal element M1, there is a tendency that the oxygen reduction activity, the carbon dioxide reduction activity, and the nitrogen reduction activity are more excellent. This tendency is significant in the case where the metal element M1 is an Fe element, and is more significant in the case where the carbon material contains the above metal element M1 (particularly, an Fe element) and a Zn element.

[0077] From the viewpoint of further improving the oxygen reduction activity, the carbon dioxide reduction activity, and the nitrogen reduction activity, the total content of the metal elements can be 0.005% by mass or more, 0.05% by mass or more, 0.1% by mass or more, or 1% by mass or more. From the viewpoint of further improving the oxygen reduction activity, the carbon dioxide reduction activity, and the nitrogen reduction activity, the total content of the metal elements can be 20% by mass or less, 5% by mass or less, 2% by mass or less, or 0.1% by mass or less. From the above viewpoint, the total content of the metal elements can be, for example, 0.005 to 20% by mass.

[0078] The total content of the metal element M1 can be 0.005 mass% or more, or 0.03 mass% or more, 0.05 mass% or more, or 1 mass% or more, from the viewpoint of further improving the oxygen reduction activity, the carbon dioxide reduction activity, and the nitrogen reduction activity. The total content of the metal element M1 can be 20 mass% or less, or 5 mass% or less, 2 mass% or less, or 0.1 mass% or less, from the viewpoint of further improving the oxygen reduction activity, the carbon dioxide reduction activity, and the nitrogen reduction activity. The total content of the metal element M1 can be, for example, 0.005 to 20 mass%, from the above viewpoints.

[0079] The content of the Zn element can be 1 mass ppm or more, or 100 mass ppm or more, 1000 mass ppm or more, or 10000 mass ppm or more, from the viewpoint of further improving the oxygen reduction activity, the carbon dioxide reduction activity, and the nitrogen reduction activity. The content of the Zn element can be 60000 mass ppm or less, or 45000 mass ppm or less, or 30000 mass ppm or less, from the viewpoint of further improving the oxygen reduction activity, the carbon dioxide reduction activity, and the nitrogen reduction activity. The content of the Zn element can be, for example, 1 to 60000 mass ppm, from the above viewpoints.

[0080] The content of the Fe element can be 1 mass ppm or more, or 100 mass ppm or more, or 500 mass ppm or more, from the viewpoint of further improving the oxygen reduction activity, the carbon dioxide reduction activity, and the nitrogen reduction activity. The content of the Fe element can be 60000 mass ppm or less, or 2500 mass ppm or less, 1500 mass ppm or less, or 1000 mass ppm or less, from the viewpoint of further improving the durability of the carbon material under an acidic condition. The content of the Fe element can be, for example, 1 to 60000 mass ppm, from the above viewpoints.

[0081] The content of the above metal element (the total content of the metal element, the total content of the metal element M1, the content of the Zn element, and the content of the Fe element) is a content based on the total mass of the carbon material, and is measured by inductively coupled plasma emission spectrometry (ICP-OES: Inductively Coupled Plasma-Optical Emission Spectrometer). The specific measurement method of the metal element using ICP-OES is described in the Examples (Experimental Examples).

[0082] The carbon material can further contain chlorine (Cl) as a constituent element. From the viewpoint of easily obtaining more excellent oxygen reduction activity, the chlorine content in the carbon material can be 30,000 mass ppm or less, 10,000 mass ppm or less, 5,000 mass ppm or less, 1,000 mass ppm or less, 500 mass ppm or less, or 100 mass ppm or less. The chlorine content can be 0 mass ppm or 10 mass ppm or more. The chlorine content is measured by combustion ion chromatography (CIC) as with the bromine content.

[0083] The carbon material can be, for example, in powder form. The median particle diameter of the carbon material can be, for example, 0.01 to 50 μm or 0.01 to 10 μm. The median particle diameter of the carbon material is the D50 particle diameter measured by a laser diffraction particle size distribution measuring device equipped with an air flow type dry disperser.

[0084] The average particle diameter of the carbon material can be, for example, 0.01 to 1 μm, 0.35 μm or less, or 0.1 μm or less, or 0.05 μm or more. Among them, when the average particle diameter of the carbon material is 0.01 to 0.35 μm, there is a tendency to easily obtain more excellent oxygen reduction activity. Note that the average particle diameter is the average primary particle diameter (average primary particle diameter), and can be calculated from the average of 40 primary particles constituting the aggregate on a two-dimensional image after ultrasonic dispersion of the sample in cyclohexane and imaging with a microscope.

[0085] The carbon material can have porosity. That is, the carbon material can be a porous carbon material (for example, a porous carbon material in powder form). The fine pores of the porous carbon material can be classified into micropores with a fine pore diameter (diameter) of less than 2 nm, mesopores with a fine pore diameter (diameter) of 2 to 50 nm, and macropores with a fine pore diameter (diameter) exceeding 50 nm according to the classification criteria of IUPAC. Among them, in the case where the carbon material has micropores and mesopores, there is a tendency to have more excellent oxygen reduction activity, carbon dioxide reduction activity, and nitrogen reduction activity. The reason is not clear, but it is presumed that a reaction field suitable for reduction reaction is formed by the fine pores such as micropores and mesopores. That is, it is presumed that the gas (oxygen, carbon dioxide, nitrogen) as a reaction material enters the above fine pores and diffuses into the carbon material, and the ionomer mediated by protons and / or water as other reaction materials also easily permeate into the carbon material, and thus the reduction reaction is easily performed.

[0086] From the viewpoint of easily obtaining an improvement effect of oxygen reduction activity, carbon dioxide reduction activity, and nitrogen reduction activity, the total volume of the micropores can be 0.03 cm 3 / g or more, 0.10 cm 3 / g or more, or 0.20 cm 3 / g or more. Based on the viewpoint that gases (oxygen, carbon dioxide, nitrogen) as reactants are easily adsorbed onto the surface of carbon materials, the total volume of micropores can be 3.00 cm³. 3 Below / g, it can also be 1.00cm 3 / g or less or 0.50cm 3 / g or less. Based on these points, the total volume of the micropores can, for example, be 0.03–3.00 cm³. 3 / g. The total volume of the micropores mentioned above is the sum of the volumes of all micropores within the carbon material, determined by nitrogen adsorption. Specifically, nitrogen adsorption-desorption experiments can be performed using the "BELSORP-max" automatic specific surface area / pore distribution measuring device manufactured by MicrotracBEL Co., Ltd., and the volume can be calculated using the MP (Micropore analysis) method with analytical software.

[0087] From the perspective of easily obtaining improved oxygen reduction activity, carbon dioxide reduction activity, and nitrogen reduction activity, the total volume of mesopores can be 0.3 cm³. 3 / g or above, or 0.4cm 3 / g or more or 0.5cm 3 / g or more. Based on the viewpoint that gases (oxygen, carbon dioxide, nitrogen) as reactants are easily adsorbed onto the surface of carbon materials, the total volume of mesopores can be 4.0 cm³. 3 Below / g, it can also be 1.5cm 3 / g or less or 1.0cm 3 / g or less. From these perspectives, the total volume of mesopores can, for example, be 0.3–4.0 cm³. 3 / g. The total volume of the mesopores mentioned above is the sum of the volumes of all mesopores within the carbon material, determined by nitrogen adsorption. Specifically, nitrogen adsorption-desorption tests can be performed using the "BELSORP-max" automatic specific surface area / pore distribution measuring device manufactured by MicrotracBEL Co., Ltd., and the volume can be calculated using the BJH (Barrett-Joyner-Halenda) method with analytical software.

[0088] Carbon materials can have macropores. The total volume of macropores can be, for example, 0.001 to 1 cm³. 3 / g.

[0089] Porous carbon materials tend to have relatively large specific surface areas. The more fine pores present, the larger the specific surface area, and therefore, the greater the specific surface area of ​​the carbon material, the better its oxygen reduction activity, carbon dioxide reduction activity, and nitrogen reduction activity. The specific surface area of ​​carbon materials measured by the single-point BET method (BET specific surface area) can be, for example, 100 m². 2 / g or more, or 200m2 / g or 300 m 2 / g or more. From the viewpoint that the gas (oxygen, carbon dioxide, nitrogen) as a reaction material is easily adsorbed on the surface of the carbon material, the BET specific surface area described above can be 2000 m 2 / g or less, or 1500 m 2 / g or less, or 1000 m 2 / g or less. From these viewpoints, the BET specific surface area described above can be, for example, 100 to 2000 m 2 / g.

[0090] The carbon material can have an electric conductivity. Specifically, the electric conductivity of the carbon material can be 0.01 S / cm or more. The electric conductivity described above can be 0.10 S / cm or more or 1.00 S / cm or more. From the viewpoint of improving the reaction efficiency in the electrode, the electric conductivity described above can be 0.01 to 50 S / cm. From the same viewpoint, the electric conductivity described above can be 20 S / cm or less or 10 S / cm or less. The electric conductivity described above is, for example, a value measured by powder resistance measurement. Specific measurement conditions are shown in the examples (experimental examples).

[0091] The carbon material described above can be obtained by firing a raw material (hereinafter also referred to as "firing raw material") containing a phthalocyanine compound having bromine (Br) as a substituent (hereinafter also referred to as "first compound"). In other words, the carbon material described above can be a fired product of the firing raw material described above.

[0092] The phthalocyanine compound has, for example, a structure represented by the following formula (1) or formula (2).

[0093]

[0094] X 1 to X 16 each independently represents a hydrogen atom or a halogen atom. Among them, in the first compound, at least one of X 1 to X 16 in the formula (1) and formula (2) described above is a bromine atom.

[0095] M in the formula (2) represents a central metal. As the central metal (M), Fe, Co, Ni, Cu, Zn, and the like can be given. Note that the phthalocyanine compound having a central metal is sometimes referred to as "iron phthalocyanine" (central metal: Fe), "zinc phthalocyanine" (central metal: Zn), and the like using a prefix corresponding to the kind of the central metal.

[0096] The first compound can not have the above-mentioned central metal (M), but in the case where the first compound has the above-mentioned central metal (M), a carbon material having more excellent oxygen reduction activity, carbon dioxide reduction activity, and nitrogen reduction activity is easily obtained. Furthermore, in the case where the first compound contains Zn as the central metal, that is, in the case where the calcination raw material contains a zinc phthalocyanine having bromine as a substituent, a carbon material having further excellent oxygen reduction activity, carbon dioxide reduction activity, and nitrogen reduction activity is easily obtained.

[0097] The halogen atom can be only a bromine atom, or a combination of a bromine atom and a halogen atom other than a bromine atom (a fluorine atom, a chlorine atom, and an iodine atom). The halogen atom can include a bromine atom and a chlorine atom.

[0098] The calcination raw material can contain a plurality of compounds having the structure represented by the above-mentioned formula (1) or formula (2) (for example, X 1 to X 16 of different kinds as the first compound.

[0099] The average number of bromine atoms of the first compound, that is, the average of the number of bromine atoms in the first compound (the number of bromine atoms per 1 molecule), is greater than 0, and can be 4 or more (for example, 4 to 16), 5 or more, 8 or more, or 11 or more, and can be 15 or less or 13 or less. In the case where the average of the number of bromine atoms in the first compound is in the above-mentioned range, a carbon material having a total volume of micropores of 0.03 to 3.00 cm 3 / g, a total volume of mesopores of 0.3 to 4.0 cm 3 / g, and a BET specific surface area of 100 to 2000 m 2 / g is easily obtained. The reason is not clear, but it is considered that the above-mentioned micropores and mesopores are formed when a part of the bromine atoms is removed by calcination, and that a carbon material having the above-mentioned surface properties corresponding to the number of bromine atoms is obtained. In addition, although the reason is not certain, it is known that the amounts of pyridine-type nitrogen and quaternary ammonium-type nitrogen in the calcination product differ depending on the number of bromine atoms in the first compound, and in the case where the above-mentioned zinc phthalocyanine is used, a carbon material having the above-mentioned peak intensity ratio I2 / I1 of 0.7 to 3.0 is easily obtained. This tendency is remarkable in the case where the calcination raw material contains a zinc phthalocyanine as the first compound.

[0100] The average number of chlorine atoms of the first compound, that is, the average of the number of chlorine atoms in the first compound (the number of chlorine atoms per 1 molecule), can be greater than 0 and 11 or less, and can be 0.1 or more, 0.5 or more, or 1 or more, and can be 3 or less or 2 or less.

[0101] The average number of halogen atoms in the first compound, that is, the average number of halogen atoms per 1 molecule of the first compound, is greater than 0, and can be 8 to 16, can be 11 or greater, can be 15 or less, or 14 or less.

[0102] The number of halogen atoms can be determined, for example, by mass spectrometry using a matrix-assisted laser desorption ionization time-of-flight mass spectrometer (JMS-S3000 manufactured by JEOL Ltd., or the like). Specifically, the number of halogen atoms can be calculated as a relative value per 1 central metal element, based on the mass ratio of the central metal element to each halogen atom in the first compound.

[0103] The first compound can be, for example, in the form of a powder. The average particle diameter of the powder composed of the first compound (average value of the long diameter of primary particles) can be 300 nm or less (for example, 10 to 300 nm), can be 200 nm or less (for example, 10 to 200 nm), 100 nm or less (for example, 10 to 100 nm), 70 nm or less (for example, 10 to 70 nm), 60 nm or less (for example, 10 to 60 nm), or 40 nm or less (for example, 10 to 40 nm), can be 40 nm or more (for example, 40 to 200 nm), or 70 nm or more (for example, 70 to 200 nm). The average aspect ratio of the powder composed of the first compound can be, for example, 1.0 to 3.0. The powder having such an average particle diameter and average aspect ratio can be produced, for example, by the method described in International Publication No. 2021 / 220495, or the like.

[0104] The calcination raw material can contain only the first compound, and can contain a component other than the first compound. From the viewpoint of easily obtaining a carbon material having more excellent oxygen reduction activity, carbon dioxide reduction activity, and nitrogen reduction activity, the content of the first compound in the calcination raw material can be 50% by mass or more, can be 80% by mass or more, or 90% by mass or more, based on the total mass of the calcination raw material. The content of the first compound in the calcination raw material can be 100% by mass, or can be 99% by mass or less, or 95% by mass or less, based on the total mass of the calcination raw material.

[0105] As the compound other than the first compound, a compound containing at least one metal element selected from the group consisting of Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Nb, Mo, Ru, Rh, Pd, Ag, Hf, Ta, W, Re, Os, Ir, Pt, Ga, and Au (hereinafter, also referred to as "second compound") can be contained in the calcined raw material. Among them, in the case where a compound containing at least one metal element selected from the group consisting of Fe, Co, Ni, Cu, Al, and Zn is used, a carbon material having more excellent oxygen reduction activity, carbon dioxide reduction activity, and nitrogen reduction activity is easily obtained. This tendency is remarkable in the case where the central metal of the first compound is Zn, and is more remarkable in the case where the central metal of the second compound is Fe. Note that the second compound is a compound different from the first compound, and is, for example, a compound not containing bromine (Br). One kind of the second compound can be used alone, or a plurality of kinds of the second compound can be used in combination.

[0106] In the above-described second compound, the above-described metal element can be a metal element contained as a central metal of a phthalocyanine compound or a porphyrin compound. That is, the second compound can be a phthalocyanine compound not having bromine as a substituent, or a porphyrin compound not having bromine as a substituent. In this case, the phthalocyanine compound and the porphyrin compound can have a halogen element (fluorine, chlorine, or iodine) other than bromine as a substituent.

[0107] The second compound can be a metal salt containing the above-described metal element. As the metal salt, a sulfate, a nitrate, a carbonate, a phosphate, a chromate, a metalloporphyrin complex, a metallophthalocyanine complex, an alkali metal salt, an alkaline earth metal salt, an earth metal salt, a transition metal salt, an ammonium salt, an acid salt, an oxoacid salt, or the like can be exemplified.

[0108] As specific examples of the second compound, metallophthalocyanines such as iron phthalocyanine, cobalt phthalocyanine, nickel phthalocyanine, copper phthalocyanine, and aluminum chlorophthalocyanine, and chloro compounds in which a part of hydrogen atoms of these metallophthalocyanines is substituted with a chlorine atom (a compound in which any one of X 1 ~ X 16 in the above-described formula (2) is a chlorine atom) can be exemplified. In addition, a tetraphenylporphyrin iron, a tris(dibenzoylmethyl)iron, a sulfate of iron (for example, ferrous sulfate heptahydrate), a ferric chloride, and a ferrous chloride (for example, ferric chloride hexahydrate, ferrous chloride tetrahydrate), and the like can be exemplified.

[0109] The second compound is, for example, in the form of a powder. The finer the powder of the second compound, the finer the sintered product, and the more excellent the oxygen reduction activity, carbon dioxide reduction activity, and nitrogen reduction activity. From this viewpoint, the average particle diameter (average of the length and diameter of primary particles) of the powder of the second compound can be 5,000 nm or less (for example, 10 to 5,000 nm), 500 nm or less, or 200 nm or less, or 30 nm or more, or 50 nm or more.

[0110] The content of the metal element, the amount of nitrogen (for example, N xps / C xps The peak intensity ratio I2 / I1, and the proportion of pores (micropores and mesopores) can vary, and thus the content of the second compound can be appropriately set in a manner that leads to the above-described carbon material, taking into account these variations.

[0111] From the viewpoint of easily obtaining a carbon material having more excellent oxygen reduction activity, carbon dioxide reduction activity, and nitrogen reduction activity, the content of the second compound in the sintering raw material can be 0.1% by mass or more, 1% by mass or more, or 5% by mass or more, based on the total amount of the first compound and the second compound. From the viewpoint of easily obtaining a carbon material having more excellent oxygen reduction activity, carbon dioxide reduction activity, and nitrogen reduction activity, the content of the second compound in the sintering raw material can be 35% by mass or less, 20% by mass or less, or 10% by mass or less, based on the total amount of the first compound and the second compound. From these viewpoints, the content of the second compound in the sintering raw material can be, for example, 0.1 to 35% by mass, based on the total amount of the first compound and the second compound.

[0112] The sintering raw material can further include, in addition to the above, an organic compound that does not include the above-described metal element. As the organic compound, for example, phenol formaldehyde resin, polyfurfuryl alcohol, furan, furan resin, phenol formaldehyde resin, epoxy resin, polyvinylidene chloride, polythiophene, polysulfone, polyvinyl alcohol, polyvinyl butyral, polyester, polylactic acid, polyether, polyether ether ketone, cellulose, carboxymethyl cellulose, lignin, pitch, polycarbazole, polyacrylic acid, polyacrylate, polymethacrylate, and polymethyl methacrylate, and the like can be listed. The sintering raw material can also include carbon materials such as graphite, activated carbon, amorphous carbon, carbon black, coal, charcoal, coke, carbon nanotubes, fullerene, graphene, and the like.

[0113] The atmosphere gas at the time of firing can be an inactive gas, an oxidizing gas, a reducing gas, or a mixed gas thereof. As the inactive gas, argon, helium, nitrogen, and the like can be exemplified. As the oxidizing gas, carbon dioxide and the like can be exemplified. As the reducing gas, hydrogen, ammonia, and the like can be exemplified. From the viewpoint of the porosity of the obtained carbon material, the atmosphere gas can contain at least one selected from the group consisting of nitrogen, ammonia, and carbon dioxide. For example, if the specific surface area is increased, a gas containing ammonia can be used. By mixing helium in ammonia, there is a tendency to increase the total volume of any of mesopores or micropores. The concentration of ammonia in the gas containing ammonia can be, for example, 0.1 to 50% by volume.

[0114] The firing temperature can be, for example, 600°C or higher, as long as the carbonization of the firing raw material is possible. The firing temperature can be 800°C or higher or 900°C or higher. The higher the firing temperature, the greater the tendency to obtain a carbon material having less amount of elements other than carbon (nitrogen, halogen elements, metal elements, and the like) and the greater the total volume of micropores and mesopores. From the viewpoint of suppressing the high crystallization of the carbon material, the firing temperature can be, for example, 1500°C or lower. From these viewpoints, the firing temperature can be, for example, 600 to 1500°C. The firing time can be, for example, 0.5 to 6 hours. The firing can be performed by one-stage heat treatment, or can be performed by two-stage or more heat treatment. For example, the firing of the raw material can be performed by performing heat treatment at a temperature lower than 600°C and then performing heat treatment at a temperature of 600°C or higher.

[0115] In the case where two-stage or more heat treatment is performed, the second stage can be performed under an atmosphere different from that of the first stage. By being under a gas atmosphere different from that of the first stage, the specific surface area, the total volume of mesopores / micropores, and the like can be easily controlled.

[0116] In one embodiment of the present disclosure, washing of the obtained fired product can be performed. That is, the fired product of the firing raw material constituting the carbon material can also be a fired product after washing. The washing method is not particularly limited, and for example, water washing, acid washing, alkali washing, and the like can be exemplified. From the viewpoint of controlling the content of metal elements, the washing method can be acid washing. As the acid, hydrochloric acid, sulfuric acid, and the like can be exemplified.

[0117] (Catalyst)

[0118] Another embodiment of the present disclosure is a catalyst (for example, an electrode catalyst) containing the carbon material of the above-described embodiment. The catalyst of one embodiment can be an oxygen reduction catalyst, can be a carbon dioxide reduction catalyst, or can be a nitrogen reduction catalyst. The oxygen reduction catalyst can be a two-electron reduction catalyst that catalyzes a two-electron reduction reaction of oxygen, or can be a four-electron reduction catalyst that catalyzes a four-electron reduction reaction of oxygen. Note that the carbon material of the above-described embodiment exhibits catalytic ability as an oxygen reduction catalyst both in an acidic condition and in an alkaline condition, and thus the oxygen reduction catalyst of the present embodiment can be used both in an acidic condition and in an alkaline condition.

[0119] (Dispersion)

[0120] Another embodiment of the present disclosure is a dispersion containing the carbon material of the above-described embodiment and a dispersion medium of the carbon material. The dispersion is used for formation of an electrode catalyst layer, and the like. That is, one embodiment of the dispersion is an ink composition for forming an electrode catalyst layer.

[0121] As described above, the carbon material of the above-described embodiment can function as an oxygen reduction catalyst, a carbon dioxide reduction catalyst, or a nitrogen reduction catalyst, and thus the above-described dispersion is useful for formation of an electrode catalyst layer for an oxygen reduction electrode (for example, a positive electrode catalyst layer of a fuel cell, an air cell, or the like, and a cathode catalyst layer of an oxygen electrolysis device), an electrode catalyst layer for a carbon dioxide reduction electrode (for example, a cathode catalyst layer of a carbon dioxide electrolysis device), or an electrode catalyst layer for a nitrogen reduction electrode (for example, a cathode catalyst layer of a nitrogen electrolysis device).

[0122] As the dispersion medium, a known dispersion medium used in formation of an electrode catalyst layer of the above-described battery and / or electrolysis device can be used. For example, water, a lower alcohol (methanol, ethanol, isopropanol, n-propanol, or the like), and a mixture thereof can be used. The content of the dispersion medium can be appropriately adjusted so that the viscosity of the dispersion becomes a viscosity suitable for a coating device. The content of the dispersion medium in the dispersion can be, for example, 60 to 99.5 mass% based on the total mass of the dispersion.

[0123] The dispersion can be composed only of the carbon material and the dispersion medium, but in addition thereto, a known material used in formation of an electrode catalyst layer of the above-described battery and / or electrolysis device can be included. The dispersion can further contain, for example, a binder of the carbon material. As the binder, a known organic high molecular compound can be used, and from the viewpoint of being able to form an ion conduction path, a polymer electrolyte can be used. As the polymer electrolyte, for example, a perfluorosulfonic acid polymer such as Nafion (registered trademark) can be given.

[0124] In the case where the dispersion liquid contains a solid component other than the carbon material (for example, the binder described above), the content of the carbon material can be 40 to 80% by mass, based on the total amount of the solid components in the dispersion liquid. The content of the binder in the dispersion liquid can be 20 to 60% by mass, based on the total amount of the solid components in the dispersion liquid. In the case where the dispersion liquid contains a polymer electrolyte, the content of the polymer electrolyte can be 20 to 60% by mass, based on the total amount of the solid components in the dispersion liquid. Note that the total amount of the solid components refers to the total amount of the components contained in the dispersion liquid other than the dispersion medium.

[0125] The dispersion liquid may, for example, further contain a carbon material other than the carbon material of the above-described embodiment. The content of the carbon material other than the carbon material of the above-described embodiment can be 40% by mass or less, based on the total amount of all the carbon materials.

[0126] (Electrode)

[0127] Another embodiment of the present disclosure is an electrode provided with an electrode catalyst layer containing the carbon material of the above-described embodiment. The electrode can be an oxygen reduction electrode (for example, a positive electrode of a fuel cell or an air cell, or a cathode of an oxygen electrolysis device), can be a carbon dioxide reduction electrode (for example, a cathode of a carbon dioxide electrolysis device), or can be a nitrogen reduction electrode (for example, a cathode of a nitrogen electrolysis device). The constitution of the electrode other than the electrode catalyst layer can employ a constitution conventionally known for an oxygen reduction electrode, a carbon dioxide reduction electrode, a nitrogen reduction electrode, and the like. The electrode of one embodiment may, for example, further be provided with a gas diffusion layer, a microporous layer, and the like.

[0128] The electrode catalyst layer can be constituted only of the carbon material, or can contain a component other than the carbon material depending on its use. As the component other than the carbon material, for example, a binder such as the polymer electrolyte described above can be given. The content of the carbon material, the binder, and the polymer electrolyte in the electrode catalyst layer (based on the total mass of the electrode catalyst layer) can be in the same range as the content of the carbon material, the binder, and the polymer electrolyte in the dispersion liquid of the above-described embodiment (based on the total amount of the solid components in the dispersion liquid).

[0129] The above-described electrode catalyst layer can be formed using the dispersion liquid of the above-described embodiment. For example, the above-described electrode catalyst layer can be obtained by applying the dispersion liquid to a support and drying it. The method of application is not particularly limited, and a general method such as a bar coater, a spray coater, a screen printer, or the like can be used.

[0130] The electrode described above can also be part of a membrane-electrode assembly (MEA) that constitutes a fuel cell. The MEA has, for example, a positive electrode catalyst layer and a negative electrode catalyst layer, an electrolyte membrane disposed between the positive electrode catalyst layer and the negative electrode catalyst layer, and a pair of gas diffusion layers disposed on the side opposite the electrolyte membrane side of the positive electrode catalyst layer and the negative electrode catalyst layer, respectively.

[0131] (Battery)

[0132] Another embodiment of the present disclosure is a battery that has the electrode of the above-described embodiment. The battery is, for example, a battery that has the electrode of the above-described embodiment as an oxygen reduction electrode (positive electrode), and can be a fuel cell or an air cell. As the fuel cell, there are, for example, a solid polymer fuel cell (PEFC), a phosphoric acid fuel cell (PAFC), an alkaline fuel cell (AFC), a molten carbonate fuel cell (MCFC), a solid oxide fuel cell (SOFC), a microbial fuel cell (MFC), and the like. The configuration of the battery other than the positive electrode can employ a configuration known in the art for fuel cells, air cells, and the like. The battery of one embodiment can be, for example, a fuel cell that has a membrane-electrode assembly (MEA) including the electrode described above.

[0133] (Electrolytic device)

[0134] Another embodiment of the present disclosure is an electrolytic device that has the electrode of the above-described embodiment. The electrolytic device can be an oxygen electrolytic device that has the electrode of the above-described embodiment as an oxygen reduction electrode (cathode), a carbon dioxide electrolytic device that has the electrode of the above-described embodiment as a carbon dioxide reduction electrode (cathode), or a nitrogen electrolytic device that has the electrode of the above-described embodiment as a nitrogen reduction electrode (cathode). The oxygen electrolytic device synthesizes hydrogen peroxide with the decomposition of oxygen, and thus can also be referred to as a hydrogen peroxide synthesizing device. The configuration of the battery other than the cathode can employ a configuration known in the art for oxygen electrolytic devices, carbon dioxide electrolytic devices, nitrogen electrolytic devices, and the like.

[0135] Examples

[0136] Hereinafter, the content of the present disclosure will be described in more detail using examples, but the present disclosure is not limited to the examples below.

[0137] <Method for measuring the number of halogens>

[0138] The number of halogens (average number of bromine and average number of chlorine) of the materials used in the examples was found by mass spectrometric analysis using JMS-S3000 manufactured by JEOL Ltd.

[0139] <Method for measuring average particle diameter>

[0140] The average particle diameter (average primary particle diameter) of the material used in the experimental examples was calculated from the average of 40 primary particles constituting the aggregate on a two-dimensional image, after the material was ultrasonically dispersed in cyclohexane and photographed using a microscope.

[0141] <Experimental Example 1>

[0142] As the raw material powder A, C.I. Pigment Green 58 (zinc phthalocyanine having bromine and chlorine as substituents, average number of bromine: 11 to 16, average number of chlorine: 0 to 5, average particle diameter: 10 to 60 nm) manufactured by DIC Corporation was prepared. Next, 1.0 g of the raw material powder A was placed in a sintering vessel (CC mark, SSA-S 5B manufactured by Nikka to; alumina 99.6%) disposed in the center of a quartz reaction tube. After nitrogen was flowed at 500 ml / min for 20 minutes to remove air remaining in the tube, the temperature was increased to 600°C (sintering temperature) at 10°C / min under nitrogen flow (500 ml / min) in a tubular furnace, and maintained for 2 hours. Then, after cooling to room temperature under nitrogen flow, the carbon material of the sintered product of the raw material powder A was taken out.

[0143] <Experimental Example 2>

[0144] The sintering temperature was changed from 600°C to 900°C, and otherwise, the carbon material was produced in the same manner as in Experimental Example 1.

[0145] <Experimental Example 3>

[0146] The raw material powder A was mixed with iron phthalocyanine ("FePc" in Table 1, manufactured by Tokyo Chemical Industry Co., Ltd., phthalocyanine iron (II), product number: P0774, average particle diameter: 110 nm, hereinafter the same.) at a mass ratio of 10:1, thereby preparing a raw material mixture A. The obtained raw material mixture A was used instead of the raw material powder A, and otherwise, the carbon material was produced in the same manner as in Experimental Example 1.

[0147] <Experimental Example 4>

[0148] The sintering temperature was changed from 600°C to 900°C, and otherwise, the carbon material was produced in the same manner as in Experimental Example 3.

[0149] <Experimental Example 5>

[0150] The raw material powder A was mixed with iron phthalocyanine at a mass ratio of 500:1, thereby preparing a raw material mixture B. The obtained raw material mixture B was used instead of the raw material powder A, and otherwise, the carbon material was produced in the same manner as in Experimental Example 2.

[0151] <Experimental Example 6>

[0152] A raw material mixture C was prepared by mixing the raw material powder A and iron phthalocyanine at a mass ratio of 2:1. A carbon material was produced in the same manner as in Experimental Example 2, except that the obtained raw material mixture C was used instead of the raw material powder A.

[0153] <Experimental Example 7>

[0154] A raw material mixture D was prepared by mixing the raw material powder A and ferrous sulfate heptahydrate ("FeS04" in Table 1, manufactured by FUJIFILM and LIGHT PURE CO., LTD., average particle diameter: 430 nm) in such a manner that the mass ratio of the raw material powder A to ferrous sulfate became 10:1. A carbon material was produced in the same manner as in Experimental Example 2, except that the obtained raw material mixture D was used instead of the raw material powder A.

[0155] <Experimental Example 8>

[0156] As the raw material powder B, C.I. Pigment Green 59 (zinc phthalocyanine having bromine and chlorine as substituents, average number of bromine: 8 to 13, average number of chlorine: 0 to 5, average particle diameter: 10 to 60 nm) manufactured by DIC Corporation was prepared. Next, a carbon material was produced in the same manner as in Experimental Example 5, except that the raw material powder B was used instead of the raw material powder A.

[0157] <Experimental Example 9>

[0158] A carbon material was produced in the same manner as in Experimental Example 2, except that zinc phthalocyanine ("ZnPc" in Table 1) manufactured by DIC Corporation was used instead of the raw material powder A.

[0159] <Experimental Example 10>

[0160] A carbon material was produced in the same manner as in Experimental Example 2, except that iron phthalocyanine was used instead of the raw material powder A.

[0161] <Experimental Example 11>

[0162] A carbon material was produced in the same manner as in Experimental Example 2, except that a mixed gas of ammonia gas and helium gas (ammonia gas concentration: 1 vol%) was used instead of nitrogen gas as the flowing gas.

[0163] <Experimental Example 12>

[0164] A carbon material was produced in the same manner as in Experimental Example 2, except that a mixed gas of ammonia gas and helium gas (ammonia gas concentration: 10 vol%) was used instead of nitrogen gas as the flowing gas.

[0165] <Experimental Example 13>

[0166] A carbon material was produced in the same manner as in Experimental Example 2, except that the carbon material of Experimental Example 2 was used instead of the raw material powder A, and carbon dioxide was used instead of nitrogen gas as the flowing gas.

[0167] <Experiment Example 14>

[0168] A carbon material was produced in the same manner as in Experiment Example 4, except that a mixed gas of ammonia and helium (ammonia concentration: 10 vol%) was used instead of nitrogen as the flow gas.

[0169] <Experiment Example 15>

[0170] A carbon material was produced in the same manner as in Experiment Example 15, except that the carbon material obtained in Experiment Example 4 was replaced with the carbon material obtained in Experiment Example 8.

[0171] <Experiment Example 16>

[0172] A carbon material was produced in the same manner as in Experiment Example 15, except that the carbon material obtained in Experiment Example 4 was replaced with the carbon material obtained in Experiment Example 8.

[0173] <Analysis>

[0174] The carbon materials obtained in Experiment Examples 1 to 16 were subjected to composition analysis and physical property analysis. Note that, in the following description, the sample refers to the carbon material that is the object of analysis.

[0175] (Composition analysis 1: elemental composition ratio N xps / C xps and peak intensity ratio I2 / I1)

[0176] The elemental composition ratio N xps / C xps of nitrogen (N) to carbon (C) in the sample was determined by X-ray photoelectron spectroscopy (XPS). Specifically, first, the sample was filled in a sample holder for powder measurement manufactured by Thermo Fisher Scientific Inc. in such a manner that the sample surface was flat, and XPS measurement (narrow scan measurement for each element) was performed using a K-Alpha manufactured by Thermo Fisher Scientific Inc., whereby the spectra of nitrogen (N1s) and carbon (C1s) were obtained. Next, the baseline was determined for each element peak by the Shirley method, and the peak area was derived. Specifically, in the spectrum of each element, the average value between the end position of the bond energy at which the signal was detected to the small side to 1.0 eV and the average value to the large side to 1.0 eV were plotted as the baseline by the Shirley method, and the peak area was derived from the integral value of the difference between the peak intensity and the baseline. In X-ray photoelectron spectroscopy, the peak area has a correlation with the content of each element, and therefore the elemental composition ratio N xps / Cxps The results are shown in Table 1. Note that the above operation and calculation were performed by the measurement / analysis software Avantage attached to the K-Alpha manufactured by ThermoFisher Scientific Inc. The measurement conditions of the XPS measurement are shown below.

[0177] [Measurement Conditions]

[0178] • Excitation X-ray source: Al-Ka ray (hV = 1486.6 eV) with a monochromator

[0179] • Static neutralization: Yes

[0180] • Charge correction: No

[0181] • Photoelectron take-off angle (tilt of the detector with respect to the sample surface): 90°

[0182] • Current: 6 mA

[0183] • Voltage: 12 kV

[0184] • Measurement diameter: 400 pm in diameter

[0185] • Data: 0.1 eV / step

[0186] • C1s spectrum measurement range: 279 eV or more and 298 eV or less

[0187] • N1s spectrum measurement range: 392 eV or more and 410 eV or less

[0188] In addition, the N1s spectrum obtained above was subjected to peak separation with the bond energy range of the peak top of the N1-type nitrogen, N2-type nitrogen, and N3-type nitrogen (N1-type: 398.5 ± 0.5 eV, N2-type: 401.2 ± 0.5 eV, N3-type: 403 ± 1.0 eV), and the peak intensity ratio I2 / I1 was calculated from the intensity I1 of the peak of the N1-type nitrogen and the intensity I2 of the peak of the N2-type nitrogen. The results are shown in Table 1.

[0189] (Elemental Composition Ratio N CHN / C CHN Measurement)

[0190] The elemental composition ratio N CHN / C CHNSpecifically, first, using a MICRO CODER JM10 (manufactured by J-SCIENCE LAB CO., Ltd.), the sample was completely combusted and gasified in a high-temperature furnace. By introducing the aforementioned gas into a thermal conductivity detector, the mass concentrations of nitrogen (N) and carbon (C) were measured, these values were divided by the atomic weights, and the ratios thereof were taken, whereby the elemental composition ratio N / C was calculated. CHN / C CHN .

[0191] (Composition analysis 3: Measurement of bromine content and chlorine content)

[0192] The bromine content (rate of all bromine in the sample) and the chlorine content (rate of all chlorine in the sample) in the sample were measured by combustion ion chromatography (CIC). Specifically, first, after weighing the sample, an automatic sample combustion device was used to combust it, and the generated gas was captured in an absorption liquid (hydrogen peroxide water) 5 mL. The absorption liquid was adjusted to 15 mL with ultrapure water, and quantitative analysis was performed using ion chromatography. In the quantitative analysis, after approximating the calibration curve for Br- ions and Cl- ions through the measurement of standard substances, the sample was measured, whereby the bromine content (mass ppm) and the chlorine content (mass ppm) in the sample were quantified. The results are shown in Table 1.

[0193] Note that the calculation formula is as follows.

[0194] • Bromine content [mass ppm] = (area of Br- ions in measurement solution - intercept of calibration curve) / slope of calibration curve × absorption liquid amount [mL] × dilution rate [times] / (sample collection amount [mg] / 1000) -

[0195] • Chlorine content [mass ppm] = (area of Cl- ions in measurement solution - intercept of calibration curve) / slope of calibration curve × absorption liquid amount [mL] × dilution rate [times] / (sample collection amount [mg] / 1000) -

[0196] (* The measurement solution is 25 μL of the injected sample)

[0197] The details of the analysis device and the measurement conditions used in the quantitative analysis are shown below.

[0198] [Analysis device]

[0199] • Automatic sample combustion device: "AQF-2100H" manufactured by Mitsubishi Chemical Analytech Co., Ltd.

[0200] • Ion chromatograph: "ICS-6000" manufactured by Thermo Fisher Scientific Inc.​​

[0201] [Measurement conditions of the automatic sample combustion device]

[0202] • Temperature: Inlet 900°C, Outlet 1000°C

[0203] • Gas flow rate: Oxygen 400 mL / min, Argon 200 mL / min, Argon water supply unit 100 mL / min

[0204] [Measurement conditions of the ion chromatograph]

[0205] • Separation column: IonPac AS19 manufactured by Thermo Fisher Scientific Inc.

[0206] • Guard column: IonPac AS19 manufactured by Thermo Fisher Scientific Inc.

[0207] • Removal system; AERS-500 (external mode)

[0208] • Detector: Conductivity detector

[0209] • Eluent: Potassium hydroxide aqueous solution (using an eluent generator ECG III)

[0210] • Eluent flow rate: 1 mL / min

[0211] • Sample injection amount: 25 μL

[0212] (Composition analysis 4: Measurement of zinc content and iron content)

[0213] A sample 0.25 g and nitric acid 8 mL were put in a 110 mL polytetrafluoroethylene-made closed container (MARS6 exclusive product, iPrep manufactured by CEM Corporation, USA) for a microwave decomposition system (MARS6 manufactured by CEM Corporation, USA), and the closed container was set in the microwave decomposition system, and pretreatment was performed at 250°C for 20 minutes, whereby the sample was decomposed. The extracted solution was diluted with ultrapure water to 100, 1000, 100000 times, whereby a measurement solution was prepared. In an ICP emission spectrometry standard solution (a mixture of 23 elements), nitric acid was added, and calibration curve preparation samples of 7 concentrations of 0, 5, 10, 50, 100, 500, 3000 ppb were prepared. Measurement of the calibration curve preparation samples was performed with a high-frequency inductively coupled plasma emission spectrometry device ("Optima8300" manufactured by PerkinElmer Japan), and a calibration curve with respect to the contents of iron and zinc elements was prepared. Then, by performing measurement of the measurement solution containing the aforementioned sample decomposed product, the iron content and the zinc content were calculated. The results are shown in Table 1.

[0214] (Measurement of BET specific surface area (Property analysis 1))

[0215] The BET specific surface area of the sample was measured by a nitrogen adsorption method. The measurement was performed using a full-automatic specific surface area measuring device Macsorb HM model-1208 (manufactured by Mountech Co., Ltd.) based on the "Measurement method of gas adsorption amount by single point method" prescribed in Appendix 2 of Japanese Industrial Standard JIS Z 8830-1990. The results are shown in Table 1.

[0216] (Measurement of pore volume (Property analysis 2))

[0217] The carbon material was put into a sample tube, and a pretreatment at 100°C for 2 hours under reduced pressure (10"2kPa or less) was performed using BELPREP vac II (manufactured by MicrotracBEL Co., Ltd.). Then, the sample tube was installed in BELSORP-max, and nitrogen was adsorbed and desorbed at -196°C while changing the relative pressure. The obtained adsorption and desorption isotherm was analyzed using an analysis software (manufactured by MicrotracBEL Co., Ltd., software name "BELMaster"), and the total volume of mesopores was calculated based on the BJH method, and the total volume of micropores was calculated based on the MP method. The results are shown in Table 1.

[0218] (Measurement of electrical conductivity (Property analysis 3))

[0219] The electrical conductivity [S / cm] of the sample was measured using an automatic powder resistance measuring system (MCP-PD600 type, manufactured by Nittoseiko Analytech Co., Ltd.). The automatic powder resistance measuring system used a system composed of a low-resistance probe unit, an automatic hydraulic pump, a main body control section, and a low-resistance meter Loresta GX (MCP-T700 type, manufactured by Nittoseiko Analytech Co., Ltd.). After the carbon material was put into the low-resistance probe unit, the volume resistivity [Ω·cm] at the time when a load of 12 kN was applied was measured, and the reciprocal thereof was taken as the electrical conductivity [S / cm]. The results are shown in Table 1.

[0220] [Table 1]

[0221]

[0222] [Evaluation]

[0223] (Evaluation of oxygen reduction activity)

[0224] [Acidic condition]

[0225] The oxygen reduction activity of the carbon material of Experimental Examples 1 to 16 under acidic conditions was evaluated using the following method. In addition, as a reference example, the oxygen reduction activity of a platinum-supported carbon (trade name: TEC10E10E, manufactured by Tanaka Kikinzoku Kogyo K.K.) that has been used as a catalyst for an oxygen reduction electrode of a fuel cell was also evaluated.

[0226] First, 4.1 mg of the carbon material or platinum-supported carbon, 1680 μL of IPA (isopropyl alcohol), 420 μL of ultrapure water, and 30 μL of 5% Nafion (Sigma Aldrich; product number 510211) were measured into a tube-type bottle, and mixed by irradiating ultrasonic waves for 5 minutes, thereby obtaining a dispersion liquid. Four μL of the dispersion liquid was added to the disc portion of a platinum ring GC disc electrode (RRDE) (BAS Inc.; product number 012613; outer diameter of ring portion: 7.0 mm; inner diameter of ring portion: 5.0 mm; outer diameter of disc portion: 4.0 mm), and left to stand for about 10 minutes to dry. This was performed a total of two times, and a total of 8 μL of the dispersion liquid was applied, thereby obtaining a measurement catalyst electrode (disc electrode area: 0.126 cm 2 , catalyst loading: 123 μg / cm 2 ).

[0227] Next, the oxygen reduction activity of the measurement catalyst electrode was evaluated using a three-electrode type electrochemical cell method using an Ag / AgCl electrode (BAS Inc.; product number 012167) as a reference electrode and a Pt coil electrode (BAS Inc.; product number 012961) as a counter electrode. Specifically, first, in a 0.1 M HC104 aqueous solution saturated with nitrogen gas (N2), a range of -0.1 to 0.7 V (vs. Ag / AgCl) was subjected to cyclic scanning at a scan rate of 100 mV / s, and the measurement system was stabilized. Next, in a 0.1 M HC104 aqueous solution saturated with oxygen gas (O2), linear sweep voltammetry (LSV) measurement was performed while rotating the measurement catalyst electrode at 1600 rpm. The LSV measurement was performed by scanning a range of -0.1 to 0.7 V (vs. Ag / AgCl) at 10 mV / s from a high potential to a low potential.

[0228] The voltammogram measured using the Ag / AgCl electrode was converted to an RHE reference using the following formula (a), and the disc current value I Disk at 0.2 V (vs. RHE) and the reaction onset potential E onset were calculated. In the following formula (a), E observed is the potential on the Ag / AgCl electrode reference, and E 0 Ag / AgCl is 0.195, and the pH is 1.0.

[0229] ERHE = E 0 Ag / AgCl + 0.0590 pH + E observed … (a)

[0230] In this evaluation, the potential at which a reduction current of 0.1 mA / cm 2 was passed was set as the reaction starting potential, and the disk current value I Disk at 0.2 V (vs. RHE) was -1.5 mA / cm 2 Hereinafter, in the case where the reaction starting potential was 0.5 V or more, it was judged that the carbon material had oxygen reduction activity under acidic conditions, and the disk current value I Disk at 0.2 V (vs. RHE) was -4.0 mA / cm 2 Hereinafter, in the case where the reaction starting potential was 0.7 V or more, it was judged that the carbon material had excellent oxygen reduction activity under acidic conditions. The results are shown in Table 2.

[0231] [Table 2]

[0232]

[0233] [Alkaline conditions]

[0234] Using 0.1 M KOH aqueous solution instead of 0.1 M HCIO4 aqueous solution, and changing the range of -0.1 to 0.7 V (vs. Ag / AgCI) to the range of -0.7 to 0.1 V (vs. Ag / AgCI), otherwise, the same operation as the measurement method under the above acidic conditions was performed, and the oxygen reduction activity under alkaline conditions of the carbon materials of Experimental Examples 1 to 8 and 11 to 16 was evaluated. Herein, the value of pH of the above formula (a) for converting the voltammogram to the RHE reference was 13.

[0235] In this evaluation, the potential at which a reduction current of 0.1 mA / cm 2 was passed was set as the reaction starting potential, and the disk current value I Disk at 0.4 V (vs. RHE) was -2.0 mA / cm 2 Hereinafter, in the case where the reaction starting potential was 0.7 V or more, it was judged that the carbon material had oxygen reduction activity under alkaline conditions, and the disk current value I Disk at 0.4 V (vs. RHE) was -3.5 mA / cm 2 Hereinafter, in the case where the reaction starting potential was 0.85 V or more, it was judged that the carbon material had excellent oxygen reduction activity under alkaline conditions. The results are shown in Table 3.

[0236] [Table 3]

[0237]

[0238] (Evaluation of carbon dioxide reduction activity)

[0239] The carbon dioxide reduction activity of the carbon materials of Experimental Examples 1 to 16 was evaluated by the following method.

[0240] First, a catalyst electrode for measurement was prepared in the same manner as in the evaluation of oxygen reduction activity. Next, the reference electrode was an Ag / AgCl electrode (BAS Inc.; product number 012167), the counter electrode was a Pt coil electrode (BAS Inc.; product number 012961), and the carbon dioxide reduction activity of the catalyst electrode for measurement was evaluated by a three-electrode electrochemical cell method. Specifically, first, after the measurement system was stabilized by performing cyclic voltammetry in the range of -1.8 to -0.7 V (vs. Ag / AgCl) at a scan rate of 100 mV / s in a 0.5 M KHCO3 aqueous solution saturated with argon (Ar), LSV measurement was performed while rotating the catalyst electrode for measurement at 1600 rpm, whereby a voltammogram was obtained. Next, LSV measurement was performed while rotating the catalyst electrode for measurement at 1600 rpm in a 0.5 M KHCO3 aqueous solution saturated with carbon dioxide (CO2), whereby a voltammogram was obtained. The LSV measurement was performed by scanning the range of -0.8 to -0.1 V (vs. RHE) at a rate of 5 mV / s from a high potential to a low potential. The voltammogram obtained by subtracting the voltammogram under argon saturation from the voltammogram under carbon dioxide saturation was taken as the voltammogram of the carbon dioxide reduction reaction, and the current value at -0.7 V (vs. RHE) was calculated by converting the obtained voltammogram to the RHE reference using the above-described formula (a). Here, the value of pH used in the above-described formula (a) for converting the voltammogram to the RHE reference was 8.36. The greater the current value in the negative direction in the voltammogram of the carbon dioxide reduction reaction, the higher the carbon dioxide reduction activity.

[0241] In this evaluation, the current value at -0.7 V (vs. RHE) in the voltammogram of the carbon dioxide reduction reaction was -0.05 mA / cm 2 In the following cases, the carbon material was judged to have carbon dioxide reduction activity (Evaluation A or B), and the current value at -0.7 V (vs. RHE) in the voltammogram of the carbon dioxide reduction reaction was lower than -0.4 mA / cm 2 In the following cases, the carbon material was judged to have excellent carbon dioxide reduction activity (Evaluation A). The evaluation results are shown in Table 4. Note that the evaluation results of Experimental Examples in which the carbon material was judged not to have carbon dioxide reduction activity are denoted as C.

[0242] (Evaluation of nitrogen reduction activity)

[0243] The nitrogen reduction activity of the carbon materials of Experimental Examples 1 to 16 was evaluated by the following method.

[0244] First, a catalyst electrode for measurement was prepared in the same manner as in the evaluation of the oxygen reduction activity. Next, the reference electrode used an Ag / AgCl electrode (BAS Inc.; product number 012167), the counter electrode used a Pt coil electrode (BAS Inc.; product number 012961), and the nitrogen reduction activity of the catalyst electrode for measurement was evaluated by a three-electrode electrochemical cell method. Specifically, first, after the measurement system was stabilized by performing cyclic voltammetry in the range of -1.7 to -0.5 V (vs. Ag / AgCl) at a scan rate of 100 mV / s in a 0.1 M Na2SO4 aqueous solution saturated with argon (Ar), LSV measurement was performed while rotating the catalyst electrode for measurement at 1600 rpm, whereby a voltammogram was obtained. Next, LSV measurement was performed while rotating the catalyst electrode for measurement at 1600 rpm in a 0.1 M Na2SO4 aqueous solution saturated with nitrogen (N2), whereby a voltammogram was obtained. The LSV measurement was performed by scanning the range of -0.8 to 0 V (vs. RHE) at 5 mV / s from a high potential to a low potential. The voltammogram obtained by subtracting the voltammogram under argon saturation from the voltammogram under nitrogen saturation was taken as the voltammogram of the nitrogen reduction reaction, and the current value at -0.8 V (vs. RHE) was calculated by converting the obtained voltammogram to the RHE reference using the above-described formula (a). Here, the value of the pH used in the above-described formula (a) for converting the voltammogram to the RHE reference was 5.8. The greater the current value in the negative direction in the voltammogram of the nitrogen reduction reaction, the higher the nitrogen reduction activity.

[0245] In the present evaluation, the current value at -0.8 V (vs. RHE) in the voltammogram of the nitrogen reduction reaction was -0.02 mA / cm 2 In the following cases, the carbon material was judged to have nitrogen reduction activity (Evaluation A or B), and the current value at -0.8 V (vs. RHE) in the voltammogram of the nitrogen reduction reaction was lower than -0.3 mA / cm 2 In the following cases, the carbon material was judged to have excellent nitrogen reduction activity (Evaluation A). The results are shown in Table 4. Note that the evaluation results of Experimental Examples in which the carbon material was judged not to have nitrogen reduction activity are denoted as C.

[0246] [Table 4]

[0247]

Claims

1. A carbon material, comprising at least carbon, nitrogen, and bromine as constituent elements. The bromine content, determined by combustion ion chromatography, ranges from 50 to 100,000 ppm by mass. The number of carbon atoms C measured by X-ray photoelectron spectroscopy xps And the number of nitrogen atoms N xps Satisfying 0.005≤N xps / C xps ≤0.

300.

2. The carbon material according to claim 1, wherein it contains at least one metallic element selected from the group consisting of Fe, Co, Ni, Cu and Zn as a constituent element.

3. The carbon material according to claim 2, wherein, The total content of the metal elements, determined by inductively coupled plasma atomic emission spectrometry, was 0.005–20% by mass.

4. The carbon material according to claim 2, wherein, The Fe content, determined by inductively coupled plasma atomic emission spectrometry, ranged from 1 to 60,000 ppm by mass.

5. The carbon material according to claim 2, wherein, The Zn content, determined by inductively coupled plasma atomic emission spectrometry, ranged from 1 to 60,000 ppm by mass.

6. The carbon material according to claim 1, wherein, In the N1s spectrum measured by X-ray photoelectron spectroscopy, the peak intensities I1 at 398.5±0.5 eV and I2 at 401.2±0.5 eV satisfy 0.7≤I2 / I1≤3.

0.

7. The carbon material according to claim 1, wherein, The number of carbon atoms (C) was quantified by elemental analysis of CHN using a combustion method. CHN And the number of nitrogen atoms N CHN Satisfying 0.005≤N CHN / C CHN ≤0.

300.

8. The carbon material according to claim 1, wherein it is a porous powder.

9. The carbon material according to claim 8, wherein, The specific surface area measured by the single-point BET method is 100–2000 m². 2 / g.

10. The carbon material according to claim 8, wherein it has micropores with a pore size of less than 2 nm. The total volume of the micropores, determined by nitrogen adsorption, is 0.03–3.00 cm³. 3 / g.

11. The carbon material according to claim 8, wherein it has mesopores with a fine pore size of 2-50 nm. The total volume of the mesopores, determined by nitrogen adsorption, is 0.3–4.0 cm³. 3 / g.

12. The carbon material according to claim 1, wherein, The conductivity is 0.01 to 50 S / cm.

13. The carbon material according to claim 1, wherein it is a calcined product of a raw material comprising a phthalocyanine compound having bromine as a substituent.

14. The carbon material according to claim 13, wherein, The phthalocyanine compound contains Zn as the central metal.

15. The carbon material according to claim 13, wherein, The raw material also contains a compound comprising at least one metallic element selected from the group consisting of Fe, Co, Ni, Cu, Al and Zn.

16. A catalyst comprising the carbon material according to any one of claims 1 to 15.

17. A dispersion comprising the carbon material according to any one of claims 1 to 15 and a dispersion medium for the carbon material.

18. The dispersion according to claim 17, wherein it contains a polymeric electrolyte.

19. An electrode comprising an electrode catalyst layer containing the carbon material according to any one of claims 1 to 15.

20. A battery having the electrodes of claim 19.

21. An electrolysis apparatus comprising the electrode of claim 19.

Images