Carbon materials, catalysts, dispersions, electrodes, batteries, and electrolysis apparatus

Abstract

Provided is a carbon material containing at least carbon, nitrogen, and bromine as constituent elements, wherein the bromine content measured by combustion ion chromatography is 50-100,000 mass ppm, and the atomic number Cxps of carbon atoms and the atomic number Nxps of nitrogen atoms determined by x-ray photoelectron spectroscopy satisfy 0.005 ≤ Nxps / Cxps ≤ 0.300.

Description

[Technical Field]

[0001] This disclosure relates to carbon materials, catalysts, dispersions, electrodes, batteries, and electrolysis apparatus. [Background technology]

[0002] Carbon materials are used in a wide range of applications due to their properties such as high electrical conductivity, high thermal conductivity, low thermal expansion coefficient, lightness, and heat resistance. In recent years, the use of nitrogen-containing carbon materials as catalysts (oxygen reduction catalysts) for the positive electrodes of fuel cells and air batteries has been investigated (see Patent Document 1). Furthermore, nitrogen-containing carbon materials may possess carbon dioxide reduction activity or nitrogen reduction activity, and are attracting attention as catalysts (carbon dioxide reduction catalysts or nitrogen reduction catalysts) for the cathodes of electrolysis devices (see Non-Patent Documents 1 and 2). [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2012-101155 [Patent Document 2] International Publication No. 2021 / 220495 [Non-patent literature]

[0004] [Non-Patent Document 1] Angew.Chem.Int.Ed., 2015, 54, 10758-10762 [Non-Patent Document 2] Nature Communications, 2019, 10, 341-348 [Overview of the project] [Problems that the invention aims to solve]

[0005] One aspect of this disclosure aims to provide novel carbon materials that can be used as electrode catalysts. [Means for solving the problem]

[0006] Some aspects of this disclosure provide the following [1] to

[21] .

[0007] [1] A carbon material containing at least carbon, nitrogen, and bromine as constituent elements, The bromine content, as measured by combustion ion chromatography, is 50 to 100,000 ppm by mass. The number of carbon atoms (C) quantified by X-ray photoelectron spectroscopy. xps and the number of atoms of nitrogen atoms N xps And, 0.005≦N xps / C xps A carbon material that satisfies the condition ≤ 0.300.

[0008] [2] The carbon material according to [1], comprising at least one metallic element selected from the group consisting of Fe, Co, Ni, Cu, and Zn as a constituent element.

[0009] [3] The carbon material according to [2], wherein the total content of the metal element, as measured by inductively coupled plasma atomic emission spectroscopy, is 0.005 to 20% by mass.

[0010] [4] The carbon material according to [2] or [3], wherein the Fe element content, as measured by inductively coupled plasma atomic emission spectrometry, is 1 to 60,000 ppm by mass.

[0011] [5] The carbon material described in [2], wherein the Zn element content, as measured by inductively coupled plasma atomic emission spectroscopy, is 1 to 60,000 ppm by mass.

[0012] [6] A carbon material according to any one of [1] to [5], wherein the N1s spectrum measured by X-ray photoelectron spectroscopy satisfies the following conditions: peak intensity I1 at 398.5 ± 0.5 eV and peak intensity I2 at 401.2 ± 0.5 eV are equal to 0.7 ≤ I2 / I1 ≤ 3.0.

[0013] [7] The number of carbon atoms C quantified by CHN elemental analysis using the combustion method CHN and the number of nitrogen atoms N C HN satisfy 0.005 ≦ N CHN / C CHN ≦ 0.300, the carbon material according to any one of [1] to [6].

[0014] [8] The carbon material according to any one of [1] to [7], which is a powdery material having porosity.

[0015] [9] The specific surface area measured by the BET single-point method is 100 to 2000 m 2 / g, the carbon material according to [8].

[0016]

[10] Having micropores with a pore diameter of less than 2 nm, the total volume of the micropores measured by the nitrogen gas adsorption method is 0.03 to 3.00 cm 3 / g, the carbon material according to [8] or [9].

[0017]

[11] Having mesopores with a pore diameter of 2 to 50 nm, the total volume of the mesopores measured by the nitrogen gas adsorption method is 0.3 to 4.0 cm 3 / g, the carbon material according to any one of [8] to

[10] .

[0018]

[12] The conductivity is 0.01 to 50 S / cm, the carbon material according to any one of [1] to

[11] .

[0019]

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

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

[0020]

[14] The carbon material according to

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

[0021]

[15] The carbon material according to

[13] or

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

[0022]

[16] A catalyst comprising a carbon material as described in any of [1] to

[15] .

[0023]

[17] A dispersion containing a carbon material described in any of [1] to

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

[0024]

[18] A dispersion according to

[17] , containing a polymer electrolyte.

[0025]

[19] An electrode comprising an electrode catalyst layer containing a carbon material as described in any of [1] to

[15] .

[0026]

[20] A battery having the electrodes described in

[19] .

[0027] [twenty one] An electrolysis apparatus having electrodes as described in

[19] . [Effects of the Invention]

[0028] According to one aspect of this disclosure, it is possible to provide novel carbon materials that can be used as electrode catalysts. [Modes for carrying out the invention]

[0029] In this specification, numerical ranges indicated using "~" represent a range that includes the numbers before and after "~" as the minimum and maximum values, respectively. Furthermore, unless otherwise explicitly stated, the units of the numbers before and after "~" are the same. In numerical ranges described in stages within this specification, the upper or lower limit of one stage of the range may be replaced with the upper or lower limit of another stage. Also, in numerical ranges described within this specification, the upper or lower limit of that range may be replaced with the values ​​shown in the examples (experimental examples). Additionally, individually described upper and lower limits can be combined in any way.

[0030] Preferred embodiments of this disclosure are described below. However, this disclosure is not limited to the embodiments described below.

[0031] (Carbon materials) One embodiment of the present disclosure contains at least carbon (C), nitrogen (N), and bromine (Br) as constituent elements, with a bromine content of 50 to 100,000 ppm by mass as measured by combustion ion chromatography (CIC), and the number of carbon atoms of C as quantified by X-ray photoelectron spectroscopy (XPS). xps and the number of atoms of nitrogen atoms N xps And, 0.005≦N xps / C xps It is a carbon material that satisfies ≤0.300. Bromine content and elemental composition ratio N xps / C xps The specific measurement method is described in the Examples (Experimental Examples). Hereafter in this specification, N xps / C xps This refers to the number of carbon atoms (C) quantified by XPS. xps and the number of atoms of nitrogen atoms N xps It means the ratio of.

[0032] The above carbon material exhibits excellent oxygen reduction activity and can therefore be used as a catalyst for oxygen reduction reactions (oxygen reduction catalyst). For example, it can be used as an electrode catalyst, such as a positive electrode catalyst for fuel cells and air batteries, or a cathode catalyst for oxygen electrolysis devices. The above carbon material also tends to exhibit carbon dioxide reduction activity and nitrogen reduction activity. Therefore, the above carbon material may also be usable as a catalyst for carbon dioxide reduction reactions (carbon dioxide reduction catalyst) and a catalyst for nitrogen reduction reactions (nitrogen reduction catalyst). Specific applications include, for example, cathode catalysts for carbon dioxide electrolysis devices and nitrogen electrolysis devices. The oxygen reduction activity, carbon dioxide reduction activity, and nitrogen reduction activity of the carbon material can be confirmed by the method described in the Examples (Experimental Examples).

[0033] Carbon materials are materials that primarily contain carbon (C), with a carbon content of 60% by mass or more. The carbon content in carbon materials can be measured by CHN elemental analysis using the combustion method. The carbon content in carbon materials may be 70% by mass or more, or 80% by mass or more.

[0034] The above bromine content may be 500 ppm by mass or more or 2000 ppm by mass or more, or 50000 ppm by mass or less or 20000 ppm by mass or less, from the viewpoint of obtaining better oxygen reduction activity.

[0035] N xps / C xps From the viewpoint of obtaining superior oxygen reduction activity, the value may be 0.010 or higher or 0.050 or higher, or 0.220 or lower or 0.140 or lower.

[0036] In the N1s spectrum measured by the above XPS, the peak intensity I1 at 398.5±0.5eV and the peak intensity I2 at 401.2±0.5eV may satisfy the condition 0.7≦I2 / I1≦3.0. In this case, superior oxygen reduction activity tends to be obtained. The reason for this is presumed to be as follows: First, in the above N1s spectrum, the peak located at 398.5±0.5eV is attributed to pyridine nitrogen, and the peak located at 401.2±0.5eV is attributed to quaternary nitrogen. Therefore, the intensity ratio of the two peaks corresponds to the ratio of the amount of quaternary nitrogen to the amount of pyridine nitrogen contained in the carbon material. It is presumed that nitrogen in the carbon material forms active sites for oxygen reduction, and it is presumed that when the amount of pyridine nitrogen and quaternary nitrogen are within a predetermined range, the balance of the amount of active sites is good, and superior oxygen reduction activity is obtained. The above peak intensity ratio I2 / I1 may be 1.0 or higher or 1.4 or higher, or 2.0 or lower or 1.5 or lower, from the viewpoint of obtaining even better oxygen reduction activity.

[0037] From the viewpoint of improving catalytic activity and conductivity, carbon materials are quantified by CHN elemental analysis using the combustion method, specifically the number of carbon atoms (C). CHN and the number of atoms of nitrogen atoms N CHN And, 0.005≦N CHN / C CHN It may also satisfy ≤0.300. Hereinafter, in this specification, N CHN / C CHN This refers to the number of carbon atoms (C) quantified by CHN elemental analysis. CHN and the number of atoms of nitrogen atoms N CHN It means the ratio of.

[0038] N CHN / C CHN From the viewpoint of further improving catalytic activity, the value may be 0.05 or higher, or 0.08 or higher. CHN / C CHN From the viewpoint of conductivity, it may be 0.2 or less, or 0.16 or less.

[0039] In carbon materials, N XPS / CXPS and N CHN / C CHN The ratio is not particularly limited, but for example, [N XPS / C XPS ] / [N CHN / C CHN [N] may be 0.7 or greater, or 0.8 or greater. XPS / C XPS ] / [N CHN / C CHN When [N] is within the above range, the catalyst activity will be superior. This is presumed to be due to the following reason. Generally, the detection depth in XPS measurement is known to be about 10 nm from the sample surface. That is, XPS measurement measures atoms present in the region (hereinafter referred to as the "surface layer") that is within a range of about 10 nm from the sample surface. Therefore, [N XPS / C XPS ] / [N CHN / C CHN A value of 0.7 or higher indicates that many nitrogen atoms are present on the surface of the sample. Since nitrogen atoms are also active sites, it is presumed that a higher concentration of nitrogen atoms on the surface of the sample leads to superior catalyst activity.

[0040] The carbon material may further contain metallic elements. Examples of metallic elements include 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), and Au (gold). The carbon material may contain one or more metallic elements. The metallic elements may, for example, be elements derived from the central metal contained in the phthalocyanine compound that serves as the raw material for the carbon material.

[0041] In one embodiment, the carbon material may contain Zn as a constituent element. In this case, it tends to exhibit superior oxygen reduction activity, carbon dioxide reduction activity, and nitrogen reduction activity.

[0042] In another embodiment, the carbon material may 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 the adsorption of gases (oxygen, carbon dioxide, nitrogen) onto the surface of the carbon material. When the carbon material contains the above metal element M1, it tends to have superior oxygen reduction activity, carbon dioxide reduction activity, and nitrogen reduction activity. This tendency is particularly pronounced when metal element M1 is the element Fe, and even more pronounced when the carbon material contains the above metal element M1 (especially the element Fe) and the element Zn.

[0043] The total content of metal elements may 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 oxygen reduction activity, carbon dioxide reduction activity and nitrogen reduction activity. The total content of metal elements may 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 viewpoint of further improving oxygen reduction activity, carbon dioxide reduction activity and nitrogen reduction activity. From the above viewpoint, the total content of metal elements may be, for example, 0.005 to 20% by mass.

[0044] The total content of metal element M1 may be 0.005% by mass or more, 0.03% by mass or more, 0.05% by mass or more, or 1% by mass or more, from the viewpoint of further improving oxygen reduction activity, carbon dioxide reduction activity and nitrogen reduction activity. The total content of metal element M1 may 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 viewpoint of further improving oxygen reduction activity, carbon dioxide reduction activity and nitrogen reduction activity. From the above viewpoint, the total content of metal element M1 may be, for example, 0.005 to 20% by mass.

[0045] From the viewpoint of further improving oxygen reduction activity, carbon dioxide reduction activity, and nitrogen reduction activity, the Zn element content may be 1 ppm by mass or more, and may be 100 ppm by mass or more, 1,000 ppm by mass or more, or 10,000 ppm by mass or more. From the viewpoint of further improving oxygen reduction activity, carbon dioxide reduction activity, and nitrogen reduction activity, the Zn element content may be 60,000 ppm by mass or less, and may be 45,000 ppm by mass or less, or 30,000 ppm by mass or less. From the above viewpoint, the Zn element content may be, for example, 1 to 60,000 ppm by mass.

[0046] The Fe element content may be 1 ppm by mass or more, 100 ppm by mass or more, or 500 ppm by mass or more, from the viewpoint of further improving oxygen reduction activity, carbon dioxide reduction activity and nitrogen reduction activity. The Fe element content may be 60,000 ppm by mass or less, 2,500 ppm by mass or less, 1,500 ppm by mass or less, or 1,000 ppm by mass or less, from the viewpoint of further improving the durability of the carbon material under acidic conditions. From the above viewpoint, the Fe element content may be, for example, 1 to 60,000 ppm by mass.

[0047] The above-mentioned content of metal elements (total content of metal elements, total content of metal element M1, content of element Zn, and content of element Fe) is based on the total mass of the carbon material and is measured by inductively coupled plasma-optical emission spectroscopy (ICP-OES). The specific method for measuring metal elements by ICP-OES is described in the Examples (Experimental Examples).

[0048] The carbon material may further contain chlorine (Cl) as a constituent element. From the viewpoint of obtaining better oxygen reduction activity, the chlorine content in the carbon material may be 30,000 ppm by mass or less, and may also be 10,000 ppm by mass or less, 5,000 ppm by mass or less, 1,000 ppm by mass or less, 500 ppm by mass or less, or 100 ppm by mass or less. The above chlorine content may be 0 ppm by mass or 10 ppm by mass or more. The above chlorine content is measured by combustion ion chromatography (CIC), similar to the above bromine content.

[0049] The carbon material may be in powder form, for example. The median diameter of the carbon material may be, for example, 0.01 to 50 μm, or 0.01 to 10 μm. The median diameter of the carbon material is the D50 particle size measured by a laser diffraction particle size distribution analyzer equipped with an airflow dry disperser.

[0050] The average particle size of the carbon material may be, for example, 0.01 to 1 μm, 0.35 μm or less, 0.1 μm or less, or 0.05 μm or more. In particular, when the average particle size of the carbon material is 0.01 to 0.35 μm, it tends to be easier to obtain better oxygen reduction activity. The average particle size is the average particle size of the primary particles (average primary particle size), which can be calculated from the average value of 40 primary particles constituting the aggregate on a two-dimensional image after ultrasonically dispersing the sample in cyclohexane and then photographing it with a microscope.

[0051] Carbon materials may be porous. That is, carbon materials may be porous carbon materials (for example, powdered porous carbon materials). According to IUPAC classification criteria, the pores in porous carbon materials can be classified into micropores (diameter less than 2 nm), mesopores (diameter 2 to 50 nm), and macropores (diameter greater than 50 nm). Among these, carbon materials with micropores and mesopores tend to have superior oxygen reduction activity, carbon dioxide reduction activity, and nitrogen reduction activity. The reason for this is not clear, but it is presumed that fine pores such as micropores and mesopores create a reaction field suitable for reduction reactions. That is, it is presumed that the gases (oxygen, carbon dioxide, nitrogen) that are reactants penetrate into the fine pores and diffuse into the carbon material, and that ions and water, which mediate other reactants such as protons, also penetrate the carbon material more easily, thereby facilitating the progress of reduction reactions.

[0052] The total volume of micropores is set at 0.03 cm³ from the viewpoint of easily obtaining the effect of improving oxygen reduction activity, carbon dioxide reduction activity, and nitrogen reduction activity. 3 It may be 0.10 cm or more, and 3 / g or more or 0.20cm 3 The concentration may be greater than or equal to / g. The total volume of micropores should be 3.00 cm³ from the viewpoint of facilitating the adsorption of reactive gases (oxygen, carbon dioxide, nitrogen) onto the carbon material surface. 3 It may be less than or equal to / g, and 1.00cm 3 / g or less or 0.50cm 3 It may be less than / g. From these viewpoints, the total volume of micropores is, for example, 0.03 to 3.00 cm³. 3 The value may be / g. The total volume of the above micropores is the sum of the volumes of all micropores in the carbon material and is measured by the nitrogen gas adsorption method. Specifically, it can be calculated by performing a nitrogen adsorption / desorption test using the BELSORP-max automatic specific surface area / pore distribution analyzer manufactured by Microtrac-Bel Corporation and using the MP (Micropore analysis) method with analysis software.

[0053] The total volume of mesopores is set at 0.3 cm, from the viewpoint of easily obtaining improvements in oxygen reduction activity, carbon dioxide reduction activity, and nitrogen reduction activity. 3 It may be 0.4cm or more, and may be 0.4g or more. 3 / g or more or 0.5cm 3 The concentration may be greater than or equal to / g. The total volume of the mesopores is 4.0 cm², from the viewpoint of facilitating the adsorption of the reactant gases (oxygen, carbon dioxide, nitrogen) onto the carbon material surface. 3 It may be less than or equal to / g, and 1.5cm 3 / g or less or 1.0cm 3 It may be less than / g. From these viewpoints, the total volume of the mesopores is, for example, 0.3 to 4.0 cm³. 3 The value may be / g. The total volume of mesopores is the sum of the volumes of all mesopores in the carbon material and is measured by nitrogen gas adsorption. Specifically, a nitrogen adsorption / desorption test is performed using the BELSORP-max automatic specific surface area / pore distribution analyzer manufactured by Microtrac-Bel Corporation, and the volume can be calculated using the BJH (Barrett-Joyner-Halenda) method with analysis software.

[0054] The carbon material may have macropores. The total volume of the macropores is, for example, 0.001 to 1 cm³. 3 / g is acceptable.

[0055] Porous carbon materials tend to have a relatively large specific surface area. Since the specific surface area increases with the number of fine pores, a larger specific surface area in a carbon material tends to result in superior oxygen reduction activity, carbon dioxide reduction activity, and nitrogen reduction activity. The specific surface area of ​​a carbon material measured by the BET single-point method (BET specific surface area) is, for example, 100 m². 2 / g or more, 200m 2 / g or more or 300m 2 It may be 1 / g or more. The above BET specific surface area is set to 2000m from the viewpoint of making it easier for the reactant gases (oxygen, carbon dioxide, nitrogen) to adsorb onto the carbon material surface. 2 It may be less than or equal to / g, and 1500m 2 / g or less or 1000m 2It may be less than / g. From these viewpoints, the BET specific surface area is, for example, 100 to 2000 m². 2 / g is acceptable.

[0056] The carbon material may be electrically conductive. Specifically, the conductivity of the carbon material may be 0.01 S / cm or higher. The conductivity may be 0.10 S / cm or higher or 1.00 S / cm or higher. From the viewpoint of improving the reaction efficiency at the electrodes, the conductivity may be between 0.01 and 50 S / cm. From a similar viewpoint, the conductivity may be 20 S / cm or lower or 10 S / cm or lower. The conductivity is a value measured, for example, by powder resistance measurement. Specific measurement conditions are shown in the Examples (Experimental Examples).

[0057] The above carbon material can be obtained by calcining a raw material (hereinafter also referred to as the "calcination raw material") containing a phthalocyanine compound having bromine (Br) as a substituent (hereinafter also referred to as the "first compound"). In other words, the above carbon material may be a calcined product of the above calcination raw material.

[0058] Phthalocyanine compounds have a structure represented by, for example, the following formula (1) or formula (2).

[0059] [ka]

[0060] [ka]

[0061] X in equations (1) and (2) 1 ~X 16 Each of these independently represents either a hydrogen atom or a halogen atom. However, in the first compound, X in formulas (1) and (2) above represents... 1 ~X 16 At least one of them is a bromine atom.

[0062] In formula (2), M represents the central metal. Examples of central metals (M) include Fe, Co, Ni, Cu, and Zn. Phthalocyanine compounds containing a central metal are sometimes called "iron phthalocyanine" (central metal: Fe), "zinc phthalocyanine" (central metal: Zn), etc., using a prefix corresponding to the type of central metal.

[0063] The first compound does not necessarily have to contain the central metal (M), but if the first compound contains the central metal (M), a carbon material with superior oxygen reduction activity, carbon dioxide reduction activity, and nitrogen reduction activity is more likely to be obtained. Furthermore, if the first compound contains Zn as the central metal, that is, if the calcination raw material contains zinc phthalocyanine with bromine as a substituent, a carbon material with even superior oxygen reduction activity, carbon dioxide reduction activity, and nitrogen reduction activity is more likely to be obtained.

[0064] The halogen atom may consist solely of a bromine atom, or it may be a combination of a bromine atom and other halogen atoms (fluorine, chlorine, and iodine atoms). The halogen atom may contain both a bromine atom and a chlorine atom.

[0065] The calcination raw material is a plurality of compounds having a structure represented by formula (1) or formula (2) above (for example, X 1 ~X 16 It may contain multiple types of compounds of different kinds.

[0066] The average number of bromine atoms in the first compound, i.e., the average number of bromine atoms in the first compound (number of bromine atoms per molecule), is greater than 0 and may be 4 or more (e.g., 4 to 16), 5 or more, 8 or more, or 11 or more, and may be 15 or less, or 13 or less. When the average number of bromine atoms in the first compound is within the above range, the total volume of micropores is 0.03 to 3.00 cm³. 3 The volume is / g, and the total volume of the mesopores is 0.3-4.0 cm³. 3 The value is / g, and the BET specific surface area is 100-2000m². 2Carbon materials with a peak intensity ratio of I2 / g are easily obtained. The reason for this is not clear, but it is thought that the above-mentioned micropores and mesopores are formed when some of the bromine atoms are removed during calcination, and that carbon materials with the above-mentioned surface properties are obtained in proportion to the number of bromine atoms. Furthermore, although the reason is not clear, it has been found that the amount of pyridine-type nitrogen and quaternary-type nitrogen in the calcined product differs depending on the number of bromine atoms in the first compound, and when using zinc phthalocyanine with the above-mentioned number of bromine atoms, carbon materials with the above-mentioned peak intensity ratio I2 / I1 of 0.7 to 3.0 are easily obtained. This tendency is particularly pronounced when the calcination raw material contains zinc phthalocyanine as the first compound.

[0067] The average number of chlorine atoms in the first compound, that is, the average number of chlorine atoms in the first compound (number of chlorine atoms per molecule), may be greater than 0 and 11 or less, and may be 0.1 or more, 0.5 or more, or 1 or more, and may be 3 or less, or 2 or less.

[0068] The average halogen number of the first compound, that is, the average of the total number of halogen atoms in the first compound (total number of halogen atoms per molecule), is greater than 0 and may be between 8 and 16, may be 11 or more, and may be 15 or less or 14 or less.

[0069] 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 (such as the JMS-S3000 manufactured by JEOL Ltd.). Specifically, the number of each halogen atom can be calculated as a relative value per central metal element from the mass ratio of the central metal element to each halogen atom in the first compound.

[0070] The first compound may be, for example, in powder form. The average particle size (average value of the major axis of the primary particles) of the powder made from the first compound may be 300 nm or less (e.g., 10 to 300 nm), 200 nm or less (e.g., 10 to 200 nm), 100 nm or less (e.g., 10 to 100 nm), 70 nm or less (e.g., 10 to 70 nm), 60 nm or less (e.g., 10 to 60 nm), or 40 nm or less (e.g., 10 to 40 nm), or 40 nm or more (e.g., 40 to 200 nm) or 70 nm or more (e.g., 70 to 200 nm). The average aspect ratio of the powder made from the first compound may be, for example, 1.0 to 3.0. Powders having such average particle size and average aspect ratio can be produced, for example, by the method described in International Publication No. 2021 / 220495, etc.

[0071] The calcination raw material may consist only of the first compound, or it may further contain components other than the first compound. From the viewpoint of making it easier to obtain carbon materials with superior oxygen reduction activity, carbon dioxide reduction activity, and nitrogen reduction activity, the content of the first compound in the calcination raw material may be 50% by mass or more, 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 may be 100% by mass, 99% by mass or less, or 95% by mass or less, based on the total mass of the calcination raw material.

[0072] The calcination raw material may further contain a compound (hereinafter also referred to as the "second 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, in addition to the first compound. Among these, when 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 with superior oxygen reduction activity, carbon dioxide reduction activity, and nitrogen reduction activity is more likely to be obtained. This tendency is particularly pronounced when the central metal of the first compound is Zn, and even more pronounced when the central metal of the second compound is Fe. The second compound is a different compound from the first compound, for example, a compound that does not contain bromine (Br). The second compound may be used alone or in combination of multiple types.

[0073] In the second compound described above, the metal element may be a metal element included as the central metal of a phthalocyanine compound or a porphyrin compound. That is, the second compound may be a phthalocyanine compound without bromine as a substituent, or a porphyrin compound without bromine as a substituent. In this case, the phthalocyanine compound and the porphyrin compound may have halogen elements other than bromine (fluorine, chlorine, or iodine) as substituents.

[0074] The second compound may be a metal salt containing the above-mentioned metal element. Examples of metal salts include sulfates, nitrates, carbonates, phosphates, chromates, metal porphyrin complexes, metal phthalocyanine complexes, alkali metal salts, alkaline earth metal salts, earth metal salts, transition metal salts, ammonium salts, hydrogenates, oxoates, and the like.

[0075] Specific examples of the second compound include metal phthalocyanines such as iron phthalocyanine, cobalt phthalocyanine, nickel phthalocyanine, copper phthalocyanine, and aluminum chloride phthalocyanine, and chlorinated compounds obtained by substituting some of the hydrogen atoms of these with chlorine atoms (X in formula (2) above). 1 ~X16 Examples include iron tetraphenylporphyrin chloride, tris(dibenzoylmethanato)ferrous sulfate (e.g., iron(II) sulfate heptahydrate), and iron chloride (e.g., iron(III) chloride hexahydrate, iron(II) chloride tetrahydrate).

[0076] The second compound is, for example, in powder form. The finer the powder made from the second compound, the finer the calcined product becomes, and the easier it is to obtain superior oxygen reduction activity, carbon dioxide reduction activity, and nitrogen reduction activity. From this viewpoint, the average particle size (average value of the major axis of the primary particles) of the powder made from the second compound may be 5000 nm or less (for example, 10 to 5000 nm), 500 nm or less, or 200 nm or less, or 30 nm or more, or 50 nm or more.

[0077] The content of the second compound in the calcination raw material determines the content of metal elements and nitrogen (e.g., N) in the calcined product (carbon material) obtained after calcination. xps / C xps Since the peak intensity ratio (I2 / I1) and the proportion of pores (micropores and mesopores) can vary, the content of the second compound may be appropriately set to obtain the carbon material described above, taking these variations into consideration.

[0078] From the viewpoint of making it easier to obtain carbon materials with superior oxygen reduction activity, carbon dioxide reduction activity, and nitrogen reduction activity, the content of the second compound in the calcined raw material may 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 making it easier to obtain carbon materials with superior oxygen reduction activity, carbon dioxide reduction activity, and nitrogen reduction activity, the content of the second compound in the calcined raw material may 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 calcined raw material may be, for example, 0.1 to 35% by mass, based on the total amount of the first compound and the second compound.

[0079] In addition to the above, the calcination raw materials may further contain organic compounds that do not contain the above metal elements. Examples of organic compounds include phenolic resins, polyfurfuryl alcohol, furan, furan resin, phenol-formaldehyde resin, epoxy resin, polyvinylidene chloride, polythiophene, polysulfone, polyvinyl alcohol, polyvinyl butyral, polyester, polylactic acid, polyether, polyetheretherketone, cellulose, carboxymethylcellulose, lignin, pitch, polycarbazole, polyacrylic acid, polyacrylic acid ester, polymethacrylic acid ester, and polymethacrylic acid. The calcination raw materials may also contain carbon materials such as graphite, activated carbon, amorphous carbon, carbon black, coal, charcoal, coke, carbon nanotubes, fullerene, and graphene.

[0080] The atmospheric gas used during firing may be an inert gas, an oxidizing gas, a reducing gas, or a mixture thereof. Examples of inert gases include argon, helium, and nitrogen. Examples of oxidizing gases include carbon dioxide. Examples of reducing gases include hydrogen and ammonia. From the viewpoint of the porosity of the resulting carbon material, the atmospheric gas may contain at least one selected from the group consisting of nitrogen, ammonia, and carbon dioxide. For example, if the specific surface area is to be improved, an ammonia-containing gas may be used. Mixing ammonia with helium tends to improve the total volume of either mesopores or micropores. The concentration of ammonia in the ammonia-containing gas may be, for example, 0.1 to 50 volume percent.

[0081] The firing temperature should be any temperature that can carbonize the raw material, for example, 600°C or higher. The firing temperature may also be 800°C or higher, or 900°C or higher. Higher firing temperatures tend to yield carbon materials with lower amounts of elements other than carbon (nitrogen, halogens, metallics, etc.), and tend to result in larger total volumes of micropores and mesopores. From the viewpoint of suppressing high crystallinity of the carbon material, the firing temperature may be, for example, 1500°C or lower. From these viewpoints, the firing temperature may be, for example, 600 to 1500°C. The firing time may be, for example, 0.5 to 6 hours. Firing may be carried out by a single heat treatment, or by two or more heat treatments. For example, the raw material may be fired by heat treatment at a temperature below 600°C followed by heat treatment at a temperature of 600°C or higher.

[0082] When performing heat treatment in two or more stages, the second stage may be carried out under a different atmosphere than the first stage. By using a different gas atmosphere for the second stage, the specific surface area, the total volume of mesopores and micropores, etc., can be easily controlled.

[0083] In one embodiment of this disclosure, the obtained calcined product may be washed. That is, the calcined product of the calcined raw materials constituting the carbon material may be a calcined product after washing. The washing method is not particularly limited and examples include washing with water, washing with acid, washing with alkali, etc. The washing method may be washing with acid from the viewpoint of controlling the content of metal elements. Examples of acids include hydrochloric acid and sulfuric acid.

[0084] (catalyst) Another embodiment of the present disclosure is a catalyst (e.g., an electrode catalyst) containing the carbon material of the above embodiment. The catalyst of the embodiment may be an oxygen reduction catalyst, a carbon dioxide reduction catalyst, or a nitrogen reduction catalyst. The oxygen reduction catalyst may be a two-electron reduction catalyst that catalyzes the two-electron reduction reaction of oxygen, or a four-electron reduction catalyst that catalyzes the four-electron reduction reaction of oxygen. Since the carbon material of the above embodiment exhibits catalytic activity as an oxygen reduction catalyst under both acidic and basic conditions, the oxygen reduction catalyst of this embodiment can be used under both acidic and basic conditions.

[0085] (dispersion) Another embodiment of the present disclosure is a dispersion containing the carbon material of the above embodiment and a dispersion medium for the carbon material. This dispersion is used for the formation of an electrode catalyst layer, etc. That is, one aspect of the dispersion is an ink composition for forming an electrode catalyst layer.

[0086] As described above, the carbon material of the above embodiment can function as an oxygen reduction catalyst, a carbon dioxide reduction catalyst, or a nitrogen reduction catalyst. Therefore, the dispersion is useful for forming an electrode catalyst layer for an oxygen reduction electrode (e.g., a positive electrode catalyst layer for fuel cells, air batteries, etc., and a cathode catalyst layer for oxygen electrolyzers), an electrode catalyst layer for a carbon dioxide reduction electrode (e.g., a cathode catalyst layer for carbon dioxide electrolyzers), or an electrode catalyst layer for a nitrogen reduction electrode (e.g., a cathode catalyst layer for nitrogen electrolyzers).

[0087] As the dispersion medium, known dispersion media used for forming electrode catalyst layers in the above-mentioned batteries and electrolysis apparatus can be used. For example, water, lower alcohols (methanol, ethanol, isopropyl alcohol, n-propyl alcohol, etc.) and mixtures thereof can be used. The content of the dispersion medium may be adjusted as appropriate so that the viscosity of the dispersion is suitable for the coating apparatus. The content of the dispersion medium in the dispersion may be, for example, 60 to 99.5% by mass based on the total mass of the dispersion.

[0088] The dispersion may consist only of a carbon material and a dispersion medium, but it may also contain known materials used for forming the electrode catalyst layer of the battery or electrolysis apparatus. The dispersion may further contain, for example, a binder for the carbon material. Known organic polymer compounds can be used as the binder, and polymer electrolytes may be used from the viewpoint of forming ion conduction paths. Examples of polymer electrolytes include perfluorosulfonic acid polymers such as Nafion®.

[0089] If the dispersion contains solids other than carbon materials (e.g., the binder mentioned above), the carbon material content may be 40 to 80% by mass, based on the total amount of solids in the dispersion. The binder content may be 20 to 60% by mass, based on the total amount of solids in the dispersion. If the dispersion contains a polymer electrolyte, the polymer electrolyte content may be 20 to 60% by mass, based on the total amount of solids in the dispersion. The total amount of solids refers to the sum of components other than the dispersion medium contained in the dispersion.

[0090] The dispersion may further contain carbon materials other than the carbon materials of the above embodiments. The content of carbon materials other than the carbon materials of the above embodiments may be 40% by mass or less, based on the total amount of all carbon materials.

[0091] (electrode) Another embodiment of the present disclosure is an electrode comprising an electrode catalyst layer containing the carbon material of the above embodiment. This electrode may be an oxygen reduction electrode (e.g., the positive electrode of a fuel cell or air battery, or the cathode of an oxygen electrolyzer), a carbon dioxide reduction electrode (e.g., the cathode of a carbon dioxide electrolyzer), or a nitrogen reduction electrode (e.g., the cathode of a nitrogen electrolyzer). The configuration of the electrode other than the electrode catalyst layer may be a configuration that is conventionally known with respect to oxygen reduction electrodes, carbon dioxide reduction electrodes, nitrogen reduction electrodes, etc. The electrode of one embodiment may further comprise, for example, a gas diffusion layer, a microporous layer, etc.

[0092] The electrode catalyst layer may consist solely of carbon material, but may also contain components other than carbon material depending on its application. Examples of components other than carbon material include binders such as the polymer electrolytes mentioned above. The range of carbon material, binder, and polymer electrolyte content in the electrode catalyst layer (based on the total mass of the electrode catalyst layer) may be the same as the range of carbon material, binder, and polymer electrolyte content in the dispersion liquid of the above embodiment (based on the total amount of solids in the dispersion liquid).

[0093] The electrode catalyst layer described above can be formed using the dispersion of the above embodiment. For example, the electrode catalyst layer may be obtained by coating the dispersion onto a support and drying it. The coating method is not particularly limited, and general methods such as bar coaters, spray coaters, and screen printers can be used.

[0094] The above electrode may be part of a membrane electrode assembly (MEA) that constitutes a fuel cell. The MEA comprises, 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 of the positive electrode catalyst layer and the negative electrode catalyst layer opposite to the electrolyte membrane side.

[0095] (battery) Another embodiment of the present disclosure is a battery comprising the electrodes of the above embodiment. This battery is, for example, a battery comprising the electrodes of the above embodiment as an oxygen reduction electrode (positive electrode), and may be a fuel cell or an air battery. Examples of fuel cells include polymer electrolyte fuel cells (PEFCs), phosphate fuel cells (PAFCs), alkaline fuel cells (AFCs), molten carbonate fuel cells (MCFCs), solid electrolyte fuel cells (SOFCs), and microbial fuel cells (MFCs). The battery configuration other than the positive electrode may adopt configurations that are conventionally known with respect to fuel cells, air batteries, etc. The battery of one embodiment may be, for example, a fuel cell comprising a membrane-electrode assembly (MEA) including the above electrodes.

[0096] (Electrolysis device) Another embodiment of this disclosure is an electrolysis apparatus equipped with the electrodes of the above embodiment. This electrolysis apparatus may be an electrolysis apparatus (oxygen electrolysis apparatus) equipped with the electrodes of the above embodiment as the oxygen reduction electrode (cathode), an electrolysis apparatus (carbon dioxide electrolysis apparatus) equipped with the electrodes of the above embodiment as the carbon dioxide reduction electrode (cathode), or an electrolysis apparatus (nitrogen electrolysis apparatus) equipped with the electrodes of the above embodiment as the nitrogen reduction electrode (cathode). An oxygen electrolysis apparatus can also be called a hydrogen peroxide synthesis apparatus because it synthesizes hydrogen peroxide in conjunction with the decomposition of oxygen. The configuration of the battery other than the cathode can be a configuration that is conventionally known with respect to oxygen electrolysis apparatuses, carbon dioxide electrolysis apparatuses, nitrogen electrolysis apparatuses, etc. [Examples]

[0097] The contents of this disclosure will be explained in more detail below using experimental examples, but this disclosure is not limited to the following experimental examples.

[0098] <Method for measuring halogen count> The halogen counts (average bromine count and average chlorine count) of the materials used in the experimental examples were determined by mass spectrometry using a JEOL Ltd. JMS-S3000.

[0099] <Method for measuring average particle size> The average particle size (average primary particle size) of the material used in the experimental example was calculated from the average value of 40 primary particles constituting the aggregates in the two-dimensional image obtained by ultrasonically dispersing the material in cyclohexane and then photographing it with a microscope.

[0100] <Experimental Example 1> As raw material powder A, CI Pigment Green 58 (zinc phthalocyanine with bromine and chlorine substituents, average bromine number: 11-16, average chlorine number: 0-5, average particle size: 10-60 nm) manufactured by DIC Corporation was prepared. Next, 1.0 g of raw material powder A was placed on a calcination boat (CC brand Nikkatoh SSA-S 5B; alumina 99.6%) and set in the center of a quartz reaction tube. After purging the air remaining in the tube by flowing nitrogen at 500 ml / min for 20 minutes, the temperature was raised to 600°C (calcination temperature) at 10°C / min under a nitrogen flow (500 ml / min) in a tubular furnace and held for 2 hours. After that, it was cooled to room temperature under a nitrogen flow, and the carbon material, which was the calcined product of raw material powder A, was removed.

[0101] <Experimental Example 2> The carbon material was prepared in the same manner as in Experimental Example 1, except that the firing temperature was changed from 600°C to 900°C.

[0102] <Experimental Example 3> Raw material mixture A was prepared by mixing raw material powder A and iron phthalocyanine (labeled "FePc" in Table 1, manufactured by Tokyo Chemical Industry Co., Ltd., iron(II) phthalocyanine, product code: P0774, average particle size: 110 nm, the same applies hereafter) in a mass ratio of 10:1. Carbon materials were prepared in the same manner as in Experimental Example 1, except that the obtained raw material mixture A was used in place of raw material powder A.

[0103] <Experimental Example 4> The carbon material was prepared in the same manner as in Experimental Example 3, except that the firing temperature was changed from 600°C to 900°C.

[0104] <Experimental Example 5> Raw material mixture B was prepared by mixing raw material powder A and iron phthalocyanine in a mass ratio of 500:1. A carbon material was prepared in the same manner as in Experimental Example 2, except that the obtained raw material mixture B was used in place of raw material powder A.

[0105] <Experimental Example 6> Raw material mixture C was prepared by mixing raw material powder A and iron phthalocyanine in a mass ratio of 2:1. A carbon material was prepared in the same manner as in Experimental Example 2, except that the obtained raw material mixture C was used in place of raw material powder A.

[0106] <Experimental Example 7> Raw material mixture D was prepared by mixing raw material powder A and iron(II) sulfate heptahydrate ("FeSO4" in Table 1, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd., average particle size: 430 nm) in a mass ratio of raw material powder A to iron(II) sulfate of 10:1. A carbon material was prepared in the same manner as in Experimental Example 2, except that the obtained raw material mixture D was used in place of raw material powder A.

[0107] <Experimental Example 8> As raw material powder B, CI Pigment Green 59 (zinc phthalocyanine with bromine and chlorine substituents, average bromine number: 8-13, average chlorine number: 0-5, average particle size: 10-60 nm) manufactured by DIC Corporation was prepared. Next, carbon materials were prepared in the same manner as in Experimental Example 5, except that raw material powder B was used instead of raw material powder A.

[0108] <Experimental Example 9> The carbon material was prepared 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 raw material powder A.

[0109] <Experimental Example 10> A carbon material was prepared in the same manner as in Experimental Example 2, except that iron phthalocyanine was used instead of raw material powder A.

[0110] <Experimental Example 11> The carbon material was prepared in the same manner as in Experimental Example 2, except that a mixed gas of ammonia and helium (ammonia concentration: 1 vol%) was used as the flowing gas instead of nitrogen.

[0111] <Experimental Example 12> A carbon material was produced in the same manner as in Experimental Example 2, except that a mixed gas of ammonia and helium (ammonia concentration: 10% by volume) was used as the flowing gas instead of nitrogen.

[0112] <Experimental Example 13> 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 raw material powder A, and carbon dioxide was used as the flowing gas instead of nitrogen.

[0113] <Experimental Example 14> A carbon material was produced in the same manner as in Experimental Example 4, except that a mixed gas of ammonia and helium (ammonia concentration: 10% by volume) was used as the flowing gas instead of nitrogen.

[0114] <0000,553><Experimental Example 15> 0.5 g of the carbon material obtained in Experimental Example 4 and 50 ml of 1 mol / L hydrochloric acid were placed in a 110 ml vial, stirred at 70 °C for 1 hour, and then filtered and washed with water. After repeating the same operation two more times, the obtained residue was dried in an oven at 90 °C overnight to produce a carbon material.

[0115] <Experimental Example 16> A carbon material was produced in the same manner as in Experimental Example 15, except that the carbon material obtained in Experimental Example 8 was used instead of the carbon material obtained in Experimental Example 4.

[0116] <Analysis> The composition analysis and physical property analysis of the carbon materials obtained in the above Experimental Examples 1 to 16 were performed. In the following description, the sample means the carbon material to be analyzed.

[0117] (Composition Analysis 1: Measurement of Elemental Composition Ratio N xps / C xps and Peak Intensity Ratio I2 / I1) The elemental composition ratio N of nitrogen (N) and carbon (C) in the sample xps / C xpsThe elemental composition ratio was determined by X-ray photoelectron spectroscopy (XPS). Specifically, first, the sample was packed into a Thermo Fisher Scientific powder sample holder so that the sample surface was flat, and XPS measurements (narrow scan measurements for each element) were performed using a Thermo Fisher Scientific K-Alpha model to obtain the spectra of nitrogen (N1s) and carbon (C1s). Next, the baseline was determined for each element's peak using the Shirley method, and the peak area was derived. Specifically, for each element's spectrum, the baseline was subtracted using the Shirley method from the average value up to 1.0 eV on the smaller side and the average value up to 1.0 eV on the larger side from the end position of the bond energy where the signal is detected. The peak area was then determined by the integral of the difference between the peak intensity and the baseline. In X-ray photoelectron spectroscopy, the peak area correlates with the content of each element, so by comparing the peak areas of each element, the elemental composition ratio N xps / C xps The following was calculated. The results are shown in Table 1. The above operations and calculations were performed using Avantage, the measurement and analysis software included with the Thermo Fisher Scientific K-Alpha model. The measurement conditions for XPS are shown below. [Measurement conditions] • Excitation X-ray source: Al-Kα rays with monochromator (hν = 1486.6 eV) • Neutralization of static charge: Yes • Charging correction: None • Photoelectron escape angle (inclination of the detector relative to the sample surface): 90° • Current: 6mA Voltage: 12kV • Measurement diameter: 400 μm Data: 0.1 eV / step • C1s spectrum measurement range: 279 eV to 298 eV • N1s spectrum measurement range: 392eV to 410eV

[0118] Also, the N1s spectrum obtained above was peak-separated within the binding energy ranges of the peak tops of 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 determined from the intensity I1 of the peak of N1-type nitrogen and the intensity I2 of the peak of N2-type nitrogen. The results are shown in Table 1.

[0119] (Composition Analysis 2: Measurement of Elemental Composition Ratio N CHN / C CHN ) The elemental composition ratio N CHN / C CHN between nitrogen (N) and carbon (C) in the sample was determined by CHN elemental analysis using a combustion method based on the Pregl-Dumas method. Specifically, first, the sample was completely combusted and gasified in a high-temperature furnace using MICRO CODER JM10 (manufactured by J Science Lab Co., Ltd.). By introducing the gas into a thermal conductivity detector, the mass concentrations of nitrogen (N) and carbon (C) were measured, and these values were divided by the atomic weights and their ratio was taken to obtain the elemental composition ratio N CHN / C CHN .

[0120] (Composition Analysis 3: Measurement of Bromine Content and Chlorine Content) The bromine content (the content ratio of total bromine in the sample) and chlorine content (the content ratio of total chlorine in the sample) in the sample were measured by combustion ion chromatography (CIC). Specifically, first, after weighing the sample, it was combusted using an automatic sample combustion device, and the generated gas was collected in 5 mL of an absorption solution (hydrogen peroxide solution). This absorption solution was adjusted to 15 mL with ultrapure water, and quantitative analysis was performed by ion chromatography. In the quantitative analysis, after approximating the calibration curves of Br-ions and Cl-ions by measuring standard substances, the bromine content (mass ppm) and chlorine content (mass ppm) in the sample were quantified by measuring the sample. The results are shown in Table 1. The calculation formula is as follows. <00时590>· Bromine content [mass ppm] = (Br area in the measurement solution - intercept of the calibration curve) / slope of the calibration curve × volume of the absorption solution [mL] × dilution factor [times] / (sample collection amount [mg] / 1000) <着000100>面積 - 検量線切片) / 検量線の傾き×吸収液量[mL]×希釈率[倍] / (試料採取量[mg] / 1000) • Chlorine content [mass ppm] = (Cl in the measurement solution) - (Area - Calibration Curve Intersection) / Slope of Calibration Curve × Volume of Absorbent Solution [mL] × Dilution Ratio [times] / (Sample Amount [mg] / 1000) (*The measurement solution is a 25 μL injection sample.)

[0121] The details of the analytical instrument and measurement conditions used for quantitative analysis are shown below. [Analyzer] • Automatic sample combustion device: Mitsubishi Chemical Analytech Co., Ltd. "AQF-2100H" • Ion chromatograph: Thermo Fisher Scientific "ICS-6000" [Measurement conditions for automatic sample combustion device] ·Temperature; Inlet900℃, Outlet1000℃ • Gas flow rates: Oxygen 400 mL / min, Argon 200 mL / min, Argon water supply unit 100 mL / min [Measurement conditions for ion chromatography] • Separation column: Thermo Fisher Scientific IonPac AS19 • Guard column; Thermo Fisher Scientific IonPac AS19 • Removal system; AERS-500 (external mode) • Detector; electrical conductivity detector • Eluent: Potassium hydroxide aqueous solution (using ECG III eluent generator) ·Eluent flow rate; 1mL / min • Sample injection volume: 25 μL

[0122] (Composition analysis 4: Measurement of zinc and iron content) 0.25 g of the sample and 8 mL of nitric acid were placed in a 110 mL polytetrafluoroethylene sealed container (iPrep, manufactured by CEM, USA, specifically for use with the MARS6 microwave decomposition system) for use with the CEM, USA microwave decomposition system. The sealed container was then set in the microwave decomposition system and pretreated at 250°C for 20 minutes to decompose the sample. The extracted solution was diluted 100, 1000, and 100,000 times with ultrapure water to prepare the measurement solution. Nitric acid was added to the ICP emission spectrometry standard solution (a mixture of 23 elements) to prepare calibration curve preparation samples at seven different concentrations: 0, 5, 10, 50, 100, 500, and 3000 ppb. The calibration curve preparation samples were measured using a high-frequency inductively coupled plasma emission spectrometer (Optima 8300, manufactured by PerkinElmer Japan), and calibration curves for the iron and zinc content were created. Subsequently, the iron and zinc content was calculated by measuring the measurement solution consisting of the aforementioned sample decomposition products. The results are shown in Table 1.

[0123] (Physical property analysis 1: Measurement of BET specific surface area) The BET specific surface area of ​​the sample was measured by nitrogen adsorption. The measurement was performed using a fully automated specific surface area analyzer, Macsorb HMmodel-1208 (manufactured by Mountec Co., Ltd.), in accordance with the "Method for measuring gas adsorption amount by single-point method" specified in Annex 2 of Japanese Industrial Standard JIS Z 8830-1990. The results are shown in Table 1.

[0124] (Physical property analysis 2: Measurement of pore volume) Carbon material was placed in a sample tube and pretreated under reduced pressure (10⁻² kPa or less) at 100°C for 2 hours using a BELPREP vac II (Microtrac-Bell). Then, the sample tube was attached to a BELSORP-max, and nitrogen gas was adsorbed and desorbed at -196°C while varying the relative pressure. The resulting adsorption / desorption isotherms were analyzed using analysis software (Microtrac-Bell, software name "BELMaster"). The total volume of mesopores was calculated according to the BJH method, and the total volume of micropores was calculated according to the MP method. The results are shown in Table 1.

[0125] (Physical property analysis 3: Measurement of electrical conductivity) The conductivity [S / cm] of a sample was measured using an automated powder resistance measurement system (MCP-PD600, manufactured by Nitto Seiko Analytech Co., Ltd.). The automated powder resistance measurement system used consisted of a low-resistance probe unit, an automated hydraulic pump, a main control unit, and a low-resistivity meter Loresta GX (MCP-T700, manufactured by Nitto Seiko Analytech Co., Ltd.). After placing a carbon material into the low-resistance probe unit, the volume resistivity [Ω·cm] was measured when a load of 12kN was applied, and the reciprocal of this was taken as the conductivity [S / cm]. The results are shown in Table 1.

[0126] [Table 1]

[0127] <Rating> (Evaluation of oxygen reduction activity) [Acidic conditions] The oxygen reduction activity of the carbon materials in Experimental Examples 1-16 under acidic conditions was evaluated using the following method. As a reference example, the oxygen reduction activity of platinum-supported carbon (product name: TEC10E10E, manufactured by Tanaka Kikinzoku Kogyo Co., Ltd.), which is conventionally used as a catalyst for oxygen reduction electrodes in fuel cells, was also evaluated.

[0128] First, 4.1 mg of 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; catalog number 510211) were measured into a vial and mixed by irradiating with ultrasound for 5 minutes to obtain a dispersion. 4 μL of the dispersion was dropped onto the disk portion of a platinum ring GC disk electrode (RRDE) (BAS, catalog number 012613, ring outer diameter: 7.0 mm, ring inner diameter: 5.0 mm, disk outer diameter: 4.0 mm), and allowed to stand for about 10 minutes to dry. This was repeated a total of two times, and a total of 8 μL of the dispersion was applied to the catalytic electrode for measurement (disk electrode area: 0.126 cm²). 2 Catalyst load: 123 μg / cm³ 2 ) was obtained.

[0129] Next, the oxygen reduction activity of the catalytic electrode was evaluated using a three-electrode electrochemical cell method, with an Ag / AgCl electrode (BAS Corporation; part number 012167) as the reference electrode and a Pt coil electrode (BAS Corporation; part number 012961) as the counter electrode. Specifically, first, the measurement system was stabilized by cycling through the range of -0.1 to 0.7 V (vs. Ag / AgCl) in a 0.1 M HClO4 aqueous solution saturated with nitrogen (N2) at a scanning speed of 100 mV / s. Next, linear sweep voltammetry (LSV) measurements were performed in a 0.1 M HClO4 aqueous solution saturated with oxygen (O2) while rotating the catalytic electrode at 1600 rpm. The LSV measurement was performed by scanning from noble potential to base potential at 10 mV / s in the range of -0.1 to 0.7 V (vs. Ag / AgCl).

[0130] The voltammogram obtained by measurement with an Ag / AgCl electrode is converted to an RHE reference using the following formula (a), and the disk current value I at 0.2V (vs. RHE) is obtained. Disk , and reaction initiation potential E onset We found that in equation (a) below, E observed This is the potential relative to the Ag / AgCl electrode, and E 0 Ag / AgCl The ratio was set to 0.195, and the pH was set to 1.0. E RHE =E 0 Ag / AgCl +0.0590 pH+E observed ...(a)

[0131] In this evaluation, 0.1 mA / cm 2 The potential at which the reduction current flows is defined as the reaction initiation potential, and the disk current value at 0.2V (vs. RHE) is I Disk -1.5mA / cm 2 The following conditions are met, and if the reaction initiation potential is 0.5V or higher, the carbon material is judged to have oxygen reduction activity under acidic conditions, and the disk current value at 0.2V (vs. RHE) I Disk -4.0mA / cm 2 The following conditions were observed, and it was determined that the carbon material possessed excellent oxygen reduction activity under acidic conditions when the reaction initiation potential was 0.7V or higher. The results are shown in Table 2.

[0132] [Table 2]

[0133] [Basic conditions] The oxygen reduction activity of carbon materials in Experimental Examples 1-8 and 11-16 under basic conditions was evaluated in the same manner as the measurement method under acidic conditions described above, except that a 0.1 M KOH aqueous solution was used instead of a 0.1 M HClO4 aqueous solution, and the range was changed from -0.1 to 0.7 V (vs. Ag / AgCl) to -0.7 to 0.1 V (vs. Ag / AgCl). However, the value substituted for pH in the above formula (a) to convert the voltammogram to the RHE standard was set to 13.

[0134] In this evaluation, 0.1 mA / cm 2 The potential at which the reduction current flows is defined as the reaction initiation potential, and the disk current value at 0.4V (vs. RHE) is I Disk -2.0mA / cm 2 The following conditions are met, and if the reaction initiation potential is 0.7V or higher, the carbon material is judged to have oxygen reduction activity under basic conditions, and the disk current value at 0.4V (vs. RHE) is I Disk -3.5mA / cm 2 The following conditions were observed, and it was determined that the carbon material possessed excellent oxygen reduction activity under basic conditions when the reaction initiation potential was 0.85V or higher. The results are shown in Table 3.

[0135] [Table 3]

[0136] (Evaluation of carbon dioxide reduction activity) The carbon dioxide reduction activity of the carbon materials in Experimental Examples 1-16 was evaluated using the following method.

[0137] First, a catalytic electrode for measurement was prepared in the same manner as for evaluating oxygen reduction activity. Next, using an Ag / AgCl electrode (BAS Corporation; product number 012167) as the reference electrode and a Pt coil electrode (BAS Corporation; product number 012961) as the counter electrode, the carbon dioxide reduction activity of the catalytic electrode for measurement was evaluated using a three-electrode electrochemical cell method. Specifically, first, the measurement system was stabilized by cycling in the range of -1.8 to -0.7 V (vs. Ag / AgCl) at a scanning speed of 100 mV / s in a 0.5 M KHCO3 (potassium bicarbonate) aqueous solution saturated with argon (Ar), and then a voltammogram was obtained by performing LSV measurement while rotating the catalytic electrode for measurement at 1600 rpm. Next, a voltammogram was obtained by performing LSV measurement in a 0.5 M KHCO3 aqueous solution saturated with carbon dioxide (CO2), while rotating the catalytic electrode for measurement at 1600 rpm. LSV measurements were performed by scanning the range from -0.8 to -0.1 V (vs. RHE) from noble potential to base potential at 5 mV / s. The voltammogram of the carbon dioxide reduction reaction was obtained by subtracting the voltammogram under argon saturation from the voltammogram under carbon dioxide saturation. The obtained voltammogram was converted to an RHE standard using equation (a) above to determine the current value at -0.7 V (vs. RHE). However, the value substituted for pH in equation (a) above to convert the voltammogram to an RHE standard was set to 8.36. In the voltammogram of the carbon dioxide reduction reaction, a larger negative current value indicates higher carbon dioxide reduction activity.

[0138] In this evaluation, the current value at -0.7V (vs. RHE) in the voltammogram of the carbon dioxide reduction reaction was -0.05 mA / cm². 2 The carbon material is judged to have carbon dioxide reduction activity (evaluation A or B) if the following conditions are met: the current value at -0.7V (vs. RHE) in the voltammogram of the carbon dioxide reduction reaction is -0.4mA / cm². 2 If the value was less than [value missing], the carbon material was judged to have excellent carbon dioxide reduction activity (evaluation A). The evaluation results are shown in Table 4. Experiments in which the carbon material was judged to have no carbon dioxide reduction activity were evaluated as C.

[0139] (Evaluation of nitrogen reduction activity) The nitrogen reduction activity of the carbon materials in Experimental Examples 1-16 was evaluated using the following method.

[0140] First, a catalytic electrode for measurement was prepared in the same manner as for evaluating oxygen reduction activity. Next, using an Ag / AgCl electrode (BAS Corporation; product number 012167) as the reference electrode and a Pt coil electrode (BAS Corporation; product number 012961) as the counter electrode, the nitrogen reduction activity of the catalytic electrode for measurement was evaluated using a three-electrode electrochemical cell method. Specifically, first, the measurement system was stabilized by cycling in the range of -1.7 to -0.5 V (vs. Ag / AgCl) at a scanning speed of 100 mV / s in a 0.1 M Na2SO4 (sodium sulfate) aqueous solution saturated with argon (Ar), and then a voltammogram was obtained by performing LSV measurement while rotating the catalytic electrode for measurement at 1600 rpm. Next, a voltammogram was obtained by performing LSV measurement in a 0.1 M Na2SO4 aqueous solution saturated with nitrogen (N2), while rotating the catalytic electrode for measurement at 1600 rpm. LSV measurements were performed by scanning the range from -0.8 to 0V (vs. RHE) from noble potential to base potential at 5mV / s. The voltammogram of the nitrogen reduction reaction was obtained by subtracting the voltammogram under argon saturation from the voltammogram under nitrogen saturation. The obtained voltammogram was converted to an RHE standard using equation (a) above to determine the current value at -0.8V (vs. RHE). However, the value substituted for pH in equation (a) above to convert the voltammogram to an RHE standard was set to 5.8. In the voltammogram of the nitrogen reduction reaction, a larger negative current value indicates higher nitrogen reduction activity.

[0141] In this evaluation, the current value at -0.8V (vs. RHE) in the voltammogram of the nitrogen reduction reaction was -0.02 mA / cm². 2 The carbon material is judged to have nitrogen reduction activity (evaluation A or B) if the following conditions are met: the current value at -0.8V (vs. RHE) in the voltammogram of the nitrogen reduction reaction is -0.3mA / cm². 2 If the value was less than [value], the carbon material was judged to have excellent nitrogen reduction activity (evaluation A). The results are shown in Table 4. Experiments in which the carbon material was judged to have no nitrogen reduction activity were evaluated as C.

[0142] Table 4

Claims

1. A porous powdered carbon material, It contains at least carbon, nitrogen, and bromine as constituent elements, and at least one metallic element selected from the group consisting of Fe, Co, Ni, Cu, and Zn. The bromine content, as measured by combustion ion chromatography, is 50 to 100,000 ppm by mass. The chlorine content, as measured by combustion ion chromatography, is between 0 and 30,000 ppm by mass. The Zn content, as measured by inductively coupled plasma atomic emission spectroscopy, is 1 to 60,000 ppm by mass. The number of carbon atoms (C) quantified by X-ray photoelectron spectroscopy. ｘｐｓ and the number of nitrogen atoms N ｘｐｓ And, 0.005 ≤ N ｘｐｓ / C ｘｐｓ Satisfying ≤ 0.300, In the N1s spectrum measured 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. The number of carbon atoms (C CHN) and the number of nitrogen atoms (N CHN), quantified by elemental analysis of CHN using the combustion method, satisfy the condition 0.005 ≤ N CHN / C CHN ≤ 0.

300. [N XPS / C XPS] / [N CHN / C CHN] is 0.7 or higher, The specific surface area measured by the BET single-point method is 100 to 2000 m² / g. It has micropores with a pore diameter of less than 2 nm and mesopores with a pore diameter of 2 to 50 nm. The total volume of the micropores, as measured by the nitrogen gas adsorption method, is 0.03 to 3.00 cm³ / g. A carbon material having a total volume of mesopores measured by nitrogen gas adsorption, which is 0.3 to 4.0 cm³ / g.

2. The carbon material according to claim 1, wherein the total content of the metal element, as measured by inductively coupled plasma atomic emission spectroscopy, is 0.005 to 20% by mass.

3. The carbon material according to claim 1, wherein the Fe element content, as measured by inductively coupled plasma atomic emission spectroscopy, is 1 to 60,000 ppm by mass.

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

5. It is a calcined product of a raw material containing a phthalocyanine compound having bromine as a substituent, The carbon material according to claim 1, wherein the phthalocyanine compound contains Zn as the central metal.

6. The carbon material according to claim 5, wherein the raw material further contains a compound comprising at least one metal element selected from the group consisting of Fe, Co, Ni, Cu, Al, and Zn.

7. A catalyst comprising the carbon material described in any one of claims 1 to 6.

8. A dispersion comprising a carbon material according to any one of claims 1 to 6 and a dispersion medium for the carbon material.

9. The dispersion according to claim 8, comprising a polymer electrolyte.

10. An electrode comprising an electrode catalyst layer containing the carbon material described in any one of claims 1 to 6.

11. A battery comprising the electrode described in claim 10.

12. An electrolysis apparatus comprising the electrodes described in claim 10.

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