Carbon catalyst, electrode, and battery

Abstract

The present invention provides: a carbon catalyst which has both high catalytic activity and high durability; an electrode; and a battery. The carbon catalyst has an L / La ratio of 18 or more, the L / La ratio being the ratio of the average carbon mesh surface size L, which is obtained by programmed-temperature desorption analysis in which the temperature can be increased to 1600°C, to the crystallite size La, which is obtained from a diffraction peak near a diffraction angle (2θ) of 43° in an X-ray diffraction pattern obtained by means of powder X-ray diffraction using a CuKα ray, and a ratio of the halogen atom concentration (atom%) to the carbon atom concentration (atom%) of 0.0005 or more as obtained by X-ray photoelectron spectroscopy.

Description

Carbon catalysts, electrodes and batteries

[0001] The present invention relates to a carbon catalyst, an electrode, and a battery.

[0002] Patent Document 1 describes a crystal structure in which the <002> interplanar spacing determined by wide-angle X-ray analysis is 3.40 to 3.60 Å, the size of the crystallites in the c-axis direction is 15 to 150 Å, and the size of the crystallites in the a-axis direction is 25 to 75 Å, and in the spectrum determined by laser Raman spectroscopy with an excitation wavelength of 532 nm, －１ Peak intensity (ID) near 1580 cm －１ The carbonaceous material is characterized in that the intensity ratio (ID / IG) of the peak intensity (IG) near the peak intensity (ID) is 0.2 to 2.0, and the Ti content obtained by ICP emission spectrometry is 0.1 to 30 wt %.

[0003] Japanese Patent Application Laid-Open No. 2018-123447

[0004] On the other hand, it has been difficult to obtain a carbon catalyst that combines high catalytic activity and high durability.

[0005] The present invention has been made in view of the above-mentioned problems, and one of its objects is to provide a carbon catalyst, an electrode, and a battery that have both high catalytic activity and high durability.

[0006] [1] A carbon catalyst according to one embodiment of the present invention for solving the above problems has an L / La ratio of 18 or more, which is a ratio of an average carbon network plane size L obtained by thermal desorption analysis capable of raising the temperature up to 1600°C to a crystallite size La obtained from a diffraction peak at a diffraction angle (2θ) of around 43° in an X-ray diffraction diagram obtained by powder X-ray diffraction using CuKα rays, and has a ratio of a halogen atom concentration (atomic %) to a carbon atom concentration (atomic %) obtained by X-ray photoelectron spectroscopy of 0.0005 or more. According to the present invention, a carbon catalyst having both high catalytic activity and high durability is provided.

[0007] [2] The carbon catalyst according to [1] may have an average carbon mesh plane size L of 5 nm or more. [3] The carbon catalyst according to [1] or [2] may have a crystallite size La of 10.00 nm or less.

[0008] [4] The carbon catalyst according to any one of [1] to [3] may contain nitrogen atoms. [5] The carbon catalyst according to any one of [1] to [4] may have a ratio of the nitrogen atom concentration (atomic %) to the carbon atom concentration (atomic %) obtained by X-ray photoelectron spectroscopy of 0.0005 or more.

[0009] [6] In the carbon catalyst according to any one of [1] to [5] above, a ratio of an area of ​​the quaternary nitrogen atomic peak to a total area of ​​the four nitrogen atomic peaks obtained by peak separation of an N1s spectrum in a spectrum obtained by X-ray photoelectron spectroscopy into the following four nitrogen atomic peaks: (1) a pyridine-type nitrogen atomic peak having a peak top in a range of 398.5±0.3 eV and a full width at half maximum of 1.4 eV; (2) a pyrrole-pyridone-type nitrogen atomic peak having a peak top in a range of 400.5±0.3 eV and a full width at half maximum of 1.4 eV; (3) a quaternary nitrogen atomic peak having a peak top in a range of 401.5±0.3 eV and a full width at half maximum of 1.4 eV; and (4) an oxidized nitrogen atomic peak having a peak top in a range of 402.5±0.3 eV and a full width at half maximum of 2.0 eV may be 0.1% or more. [7] The carbon catalyst according to any one of [1] to [6] has a BET specific surface area obtained by a nitrogen adsorption method of 50 m ２ / g or more.

[0010] [8] An electrode according to one embodiment of the present invention for solving the above problems includes the carbon catalyst according to any one of [1] to [7]. According to the present invention, an electrode having both high catalytic activity and high durability is provided.

[0011] [9] A battery according to one embodiment of the present invention for solving the above problems includes the electrode according to [8]. According to the present invention, a battery having both high catalytic activity and high durability is provided.

[0012] According to the present invention, a carbon catalyst, an electrode, and a battery that combine high catalytic activity and high durability are provided.

[0013] Fig. 10 is an explanatory diagram of a coronene model relating to an average carbon net plane size L. Fig. 11 is an explanatory diagram showing an example of a result of evaluating the characteristics of a carbon catalyst in an example according to the present embodiment.

[0014] An embodiment of the present invention will be described below, but the present invention is not limited to the example shown in this embodiment.

[0015] The carbon catalyst according to this embodiment (hereinafter referred to as "the catalyst") is a carbon material that exhibits catalytic activity. The catalyst is mainly composed of carbon. Specifically, the carbon content of the catalyst may be, for example, 70% by weight or more, preferably 75% by weight or more, more preferably 80% by weight or more, even more preferably 83% by weight or more, and particularly preferably 85% by weight or more. The carbon content of the catalyst may be, for example, 99% by weight or less, 95% by weight or less, or 93% by weight or less. The carbon content of the catalyst may be specified by any combination of any of the above-mentioned lower limit values ​​and any of the above-mentioned upper limit values. The carbon content of the carbon catalyst is obtained by elemental analysis (combustion method).

[0016] The present catalyst exhibits catalytic activity by itself. That is, the present catalyst exhibits catalytic activity without, for example, supporting a noble metal. The catalytic activity exhibited by the present catalyst is, for example, catalytic activity for a reduction reaction and / or catalytic activity for an oxidation reaction, more specifically, catalytic activity for an oxygen reduction reaction and / or catalytic activity for a hydrogen oxidation reaction, and is at least catalytic activity for an oxygen reduction reaction.

[0017] The inventors of the present invention have conducted extensive research into technical means for obtaining a carbon catalyst that combines high catalytic activity with high durability. As a result, they have independently found that a carbon catalyst having a relatively large L / La ratio, which is the ratio of an average carbon network plane size L to a crystallite size La of its carbon structure, and into which halogen atoms have been introduced, has high durability in addition to high catalytic activity, and have completed the present invention.

[0018] That is, the present catalyst has an L / La ratio of 18 or more, which is the ratio of the average carbon network plane size L obtained by thermal desorption analysis capable of heating up to 1600°C to the crystallite size La obtained from a diffraction peak at a diffraction angle (2θ) of around 43° in an X-ray diffraction pattern obtained by powder X-ray diffraction using CuKα rays.

[0019] The L / La ratio of the present catalyst is, for example, preferably 19 or more, more preferably 20 or more, even more preferably 21 or more, even more preferably 22 or more, even more preferably 23 or more, even more preferably 24 or more, even more preferably 25 or more, even more preferably 26 or more, even more preferably 27 or more, even more preferably 28 or more, and particularly preferably 29 or more.

[0020] The upper limit of the L / La ratio of the present catalyst is not particularly limited as long as the effects of the present invention can be obtained, and may be, for example, 12,500 or less, 10,000 or less, 5,000 or less, 1,000 or less, 700 or less, 500 or less, 300 or less, 200 or less, 100 or less, 50 or less, or 40 or less. The L / La ratio of the present catalyst may be specified by any combination of any of the above-mentioned lower limit values ​​and any of the above-mentioned upper limit values.

[0021] The L / La ratio contributes to improving the catalytic activity and durability of the present catalyst. That is, for example, a carbon structure having a relatively large L / La ratio contributes to effectively improving the catalytic activity and durability of the present catalyst by increasing the curved portions of the carbon net plane that serve as catalytic active sites and / or reducing edge sites of the carbon net plane that serve as catalytic active sites but can also serve as starting points for deterioration.

[0022] The average carbon network plane size L is obtained by a temperature-programmed desorption (TPD) analysis (hereinafter referred to as "high-temperature TPD") capable of raising the temperature up to 1600°C. That is, in this embodiment, the total amount of carbon edge sites of the carbon catalyst is calculated from the desorbed gas quantification result of the high-temperature TPD of the carbon catalyst using a temperature-programmed desorption analyzer (hereinafter referred to as "high-temperature TPD device") capable of raising the temperature up to 1600°C, and the average carbon network plane size L obtained from the amount is calculated using the coronene model shown in FIG. 1. ０ represents the lattice constant of 0.2461 nm in the a-axis direction of graphite crystal.

[0023] The average carbon mesh plane size L of the present catalyst is not particularly limited as long as the effects of the present invention can be obtained, but may be, for example, 5 nm or more, more preferably 10 nm or more, even more preferably 15 nm or more, even more preferably 20 nm or more, even more preferably 25 nm or more, even more preferably 30 nm or more, even more preferably 32 nm or more, even more preferably 35 nm or more, even more preferably 37 nm or more, even more preferably 40 nm or more, even more preferably 43 nm or more, even more preferably 46 nm or more, and particularly preferably 49 nm or more.

[0024] The average carbon net surface size L of the present catalyst may be, for example, 5000 nm or less, 2000 nm or less, 1000 nm or less, 500 nm or less, 400 nm or less, 300 nm or less, 200 nm or less, 100 nm or less, 90 nm or less, 80 nm or less, 70 nm or less, or 60 nm or less. The average carbon net surface size L of the present catalyst may be specified by any combination of any of the above-mentioned lower limit values ​​and any of the above-mentioned upper limit values.

[0025] The average carbon net plane size L contributes to improving the catalytic activity and durability of the present catalyst. That is, for example, a carbon structure having a relatively large average carbon net plane size L contributes to effectively improving durability by reducing edge sites of the carbon net plane that can be the starting point of deterioration.

[0026] The crystallite size La can be obtained from a diffraction peak at a diffraction angle (2θ) of about 43° in an X-ray diffraction diagram obtained by powder X-ray diffraction using CuKα radiation. Here, when a carbon catalyst has a structure in which hexagonal carbon network planes extending in the a-axis direction are connected among crystallites constituting curved carbon network planes that contribute to its catalytic activity, a diffraction peak f which is a carbon (10) diffraction line having a peak top at a diffraction angle (2θ) of about 43° (for example, in a range of 35° to 60°) in an X-ray diffraction diagram using CuKα radiation of the carbon catalyst can be obtained from a diffraction peak f １０ This diffraction peak f １０ is defined as a diffraction peak having a diffraction angle (2θ) of 43.5°±1.0° and a full width at half maximum of 7.5°±6.5°, for example.

[0027] In addition, when the carbon catalyst contains iron, a diffraction peak derived from iron may also appear at a diffraction angle (2θ) of about 43°. That is, in this case, the diffraction line derived from the carbon structure includes the above-mentioned diffraction peak f １０ Diffraction peak f Ｆｅ Therefore, for the carbon catalyst containing iron, by peak separation of the X-ray diffraction pattern as performed in the examples described later, the diffraction peak at a diffraction angle (2θ) of about 43° is separated into two diffraction peaks, namely, １０ and f Ｆｅ and separate into.

[0028] The crystallite size La is determined by the diffraction peak f １０ That is, the crystallite size La (nm) is calculated by analyzing the diffraction peak f １０The Bragg angle and full width at half maximum of the spectrum are substituted into the following Scherrer formula: La = Kλ / (β cos θ), where K is the Scherrer constant (0.94), λ is the wavelength of CuKα radiation (0.15418 nm), β is the full width at half maximum (radian), and θ is the Bragg angle (radian).

[0029] The crystallite size La of the present catalyst is not particularly limited as long as the effects of the present invention can be obtained, but for example, it may be 10.00 nm or less, preferably 5.00 nm or less, more preferably 4.00 nm or less, even more preferably 3.00 nm or less, even more preferably 2.50 nm or less, even more preferably 2.30 nm or less, even more preferably 2.00 nm or less, even more preferably 1.90 nm or less, even more preferably 1.80 nm or less, even more preferably 1.70 nm or less, even more preferably 1.60 nm or less, and particularly preferably 1.50 nm or less.

[0030] The crystallite size La of the present catalyst may be, for example, 0.50 nm or more, 0.70 nm or more, 1.00 nm or more, 1.10 nm or more, 1.20 nm or more, 1.30 nm or more, 1.40 nm or more, 1.50 nm or more, or 1.60 nm or more. The crystallite size La of the present catalyst may be specified by any combination of any of the above-mentioned lower limit values ​​and any of the above-mentioned upper limit values.

[0031] The crystallite size La contributes to improving the catalytic activity of the present catalyst. That is, for example, a carbon structure having a relatively large average carbon net plane size L and a relatively small crystallite size La contributes to effectively improving the catalytic activity by increasing the curved portions of the carbon net plane that become catalytic active sites.

[0032] The crystallite size Lc can be obtained from a diffraction peak at a diffraction angle (2θ) of about 26° in an X-ray diffraction pattern obtained by powder X-ray diffraction using CuKα radiation. Specifically, the crystallite size Lc can be obtained from a diffraction peak f which is a (002) diffraction line of carbon having a peak top at a diffraction angle 2θ of about 26° (for example, in the range of 24.0° to 26.5°) in an X-ray diffraction pattern obtained by powder X-ray diffraction using CuKα radiation. ００２ This diffraction peak f ００２ is defined as a diffraction peak having a diffraction angle (2θ) of 25.0° or more and 26.5° or less and a full width at half maximum of 0.05° or more and 20° or less.

[0033] The crystallite size Lc is determined by the diffraction peak f ００２ That is, the crystallite size Lc (nm) is calculated by analyzing the diffraction peak f ００２ It is calculated by substituting the Bragg angle and full width at half maximum of the above into the following Scherrer formula: Lc = Kλ / (β cos θ), where K is the Scherrer constant (0.94), λ is the wavelength of CuKα radiation (0.15418 nm), β is the full width at half maximum (radian), and θ is the Bragg angle (radian).

[0034] The crystallite size Lc of the present catalyst is not particularly limited as long as the effects of the present invention are obtained, but for example, it may be 10.00 nm or less, preferably 5.00 nm or less, more preferably 4.00 nm or less, even more preferably 3.00 nm or less, even more preferably 2.50 nm or less, even more preferably 2.00 nm or less, even more preferably 1.80 nm or less, even more preferably 1.50 nm or less, even more preferably 1.40 nm or less, even more preferably 1.30 nm or less, and particularly preferably 1.25 nm or less.

[0035] The crystallite size Lc of the catalyst of the present invention may be, for example, 0.50 nm or more, 0.70 nm or more, 0.80 nm or more, 0.90 nm or more, 1.00 nm or more, or 1.10 nm or more. The crystallite size Lc of the catalyst of the present invention may be specified by any combination of any of the above-mentioned lower limit values ​​and any of the above-mentioned upper limit values.

[0036] The catalyst contains halogen atoms, i.e., the ratio of the halogen atom concentration (atomic %) to the carbon atom concentration (atomic %) (hereinafter referred to as the "halogen / C ratio") obtained by X-ray photoelectron spectroscopy (hereinafter referred to as "XPS") is 0.0005 or more.

[0037] The halogen / C ratio of the present catalyst is, for example, preferably 0.0010 or more, more preferably 0.0030 or more, even more preferably 0.0050 or more, even more preferably 0.0080 or more, even more preferably 0.0100 or more, even more preferably 0.0110 or more, even more preferably 0.0120 or more, even more preferably 0.0130 or more, even more preferably 0.0140 or more, and particularly preferably 0.0145 or more.

[0038] The upper limit of the halogen / C ratio of the present catalyst is not particularly limited as long as the effects of the present invention can be obtained, but may be, for example, 0.1000 or less, 0.0700 or less, 0.0500 or less, 0.0450 or less, 0.0400 or less, 0.0350 or less, 0.0300 or less, 0.0250 or less, 0.0200 or less, 0.0190 or less, 0.0180 or less, 0.0170 or less, or 0.0160 or less. The halogen / C ratio of the present catalyst may be specified by any combination of any of the above-mentioned lower limit values ​​and any of the above-mentioned upper limit values.

[0039] The halogen atom contained in the catalyst is not particularly limited as long as the effects of the present invention can be obtained, but is preferably at least one selected from the group consisting of a fluorine atom, a chlorine atom, a bromine atom, and an iodine atom. Although a chlorine atom is used as the halogen atom in the examples described below, halogen atoms are not limited to chlorine atoms and have a common feature in that they have seven valence electrons in their outermost shells and form single bonds with carbon atoms present at edge sites of the carbon net plane contained in the carbon structure, thereby forming a closed shell structure.

[0040] The halogen / C ratio of the catalyst is calculated by dividing the halogen atom concentration (atomic %) obtained by XPS of the catalyst by the carbon atom concentration (atomic %). In this regard, when the catalyst contains two or more types of halogen atoms, the halogen atom concentration (atomic %) of the catalyst is the sum of the concentrations (atomic %) of the two or more types of halogen atoms obtained by XPS.

[0041] The halogen / C ratio contributes to improving the catalytic activity and durability of the catalyst. That is, for example, an increase in the halogen / C ratio in the carbon structure contributes to effectively improving durability by increasing the number of edge sites to which halogen atoms are bonded among the edge sites of the carbon net plane contained in the carbon structure.

[0042] Here, the amount of halogen atoms introduced into the carbon structure is related to the amount of edge sites contained in the carbon structure, i.e., for example, a carbon structure having a relatively large average carbon lattice plane size L has few edge sites of the carbon lattice plane contained in the carbon structure, and therefore the halogen / C ratio does not become very large.

[0043] The halogen atom concentration of the catalyst obtained by XPS is not particularly limited as long as the effects of the present invention can be obtained, but may be, for example, 0.10 (atomic %) or more, preferably 0.20 (atomic %) or more, more preferably 0.30 (atomic %) or more, even more preferably 0.40 (atomic %) or more, still more preferably 0.50 (atomic %) or more, still more preferably 0.60 (atomic %) or more, still more preferably 0.70 (atomic %) or more, still more preferably 0.80 (atomic %) or more, still more preferably 0.90 (atomic %) or more, still more preferably 1.00 (atomic %) or more, still more preferably 1.05 (atomic %) or more, still more preferably 1.10 (atomic %) or more, still more preferably 1.15 (atomic %) or more, still more preferably 1.20 (atomic %) or more, still more preferably 1.25 (atomic %) or more, and particularly preferably 1.30 (atomic %) or more.

[0044] The halogen atom concentration of the catalyst obtained by XPS may be, for example, 15.00 (atomic%) or less, 10.00 (atomic%) or less, 7.00 (atomic%) or less, 5.00 (atomic%) or less, 3.50 (atomic%) or less, 3.00 (atomic%) or less, 2.50 (atomic%) or less, 2.00 (atomic%) or less, 1.70 (atomic%) or less, or 1.50 (atomic%) or less. The halogen atom concentration of the catalyst obtained by XPS may be specified by any combination of any of the above-mentioned lower limit values ​​and any of the above-mentioned upper limit values.

[0045] The halogen atom concentration obtained by XPS contributes to improving the durability of the present catalyst. That is, for example, an increase in the halogen atom concentration in the carbon structure contributes to an effective improvement in durability by increasing the number of edge sites to which halogen atoms are bonded among the edge sites of the carbon net plane contained in the carbon structure.

[0046] As described above, the amount of halogen atoms introduced into a carbon structure is related to the amount of edge sites contained in the carbon structure. For example, a carbon structure having a relatively large average carbon mesh plane size L has a small number of edge sites of the carbon mesh plane contained in the carbon structure, and therefore the halogen atom concentration does not become very large.

[0047] The catalyst preferably contains nitrogen atoms. That is, the catalyst preferably contains nitrogen atoms doped into the carbon structure. Specifically, the catalyst may have a ratio of the nitrogen atom concentration (atomic %) to the carbon atom concentration (atomic %) obtained by XPS (hereinafter referred to as the "N / C ratio") of 0.0005 or more.

[0048] In this case, the N / C ratio of the present catalyst is, for example, preferably 0.0010 or more, more preferably 0.0050 or more, even more preferably 0.0100 or more, even more preferably 0.0130 or more, even more preferably 0.0150 or more, and particularly preferably 0.0170 or more.

[0049] The N / C ratio of the present catalyst may be, for example, 0.3000 or less, 0.2000 or less, 0.1000 or less, 0.0700 or less, 0.0500 or less, or 0.0400 or less. The N / C ratio of the present catalyst may be specified by any combination of any of the above-mentioned lower limit values ​​and any of the above-mentioned upper limit values.

[0050] The N / C ratio contributes to improving the catalytic activity and durability of the catalyst, i.e., for example, an increase in the N / C ratio in the carbon structure contributes to an effective improvement in catalytic activity by increasing the catalytic active sites derived from the nitrogen atoms contained in the carbon structure.

[0051] The nitrogen atom concentration of the catalyst obtained by XPS is not particularly limited as long as the effects of the present invention can be obtained, but may be, for example, 0.05 (atomic %) or more, preferably 0.10 (atomic %) or more, more preferably 0.30 (atomic %) or more, even more preferably 0.50 (atomic %) or more, even more preferably 0.70 (atomic %) or more, even more preferably 1.00 (atomic %) or more, even more preferably 1.10 (atomic %) or more, even more preferably 1.20 (atomic %) or more, even more preferably 1.30 (atomic %) or more, even more preferably 1.40 (atomic %) or more, even more preferably 1.50 (atomic %) or more, even more preferably 1.60 (atomic %) or more, even more preferably 1.70 (atomic %) or more, and particularly preferably 1.80 (atomic %) or more.

[0052] The nitrogen atom concentration of the present catalyst obtained by XPS may be, for example, 30.00 (atomic%) or less, 25.00 (atomic%) or less, 20.00 (atomic%) or less, 15.00 (atomic%) or less, 10.00 (atomic%) or less, 7.00 (atomic%) or less, 5.00 (atomic%) or less, 4.00 (atomic%) or less, or 3.00 (atomic%) or less. The nitrogen atom concentration of the present catalyst obtained by XPS may be specified by any combination of any of the above-mentioned lower limit values ​​and any of the above-mentioned upper limit values.

[0053] The nitrogen atom concentration obtained by XPS contributes to improving the catalytic activity and durability of the present catalyst. That is, for example, an increase in the nitrogen atom concentration in the carbon structure contributes to an effective improvement in catalytic activity by increasing the catalytic active sites derived from the nitrogen atoms contained in the carbon structure.

[0054] The catalyst has the following four nitrogen atom peaks in the N1s spectrum obtained by XPS: (1) a pyridine-type nitrogen atom peak (a peak derived from a pyridine-type nitrogen atom) having a peak top in the range of 398.5±0.3 eV and a full width at half maximum of 1.4 eV; (2) a pyrrole-pyridone-type nitrogen atom peak (a peak derived from a pyrrole-type nitrogen atom and a pyridone-type nitrogen atom) having a peak top in the range of 400.5±0.3 eV and a full width at half maximum of 1.4 eV; (3) a quaternary-type nitrogen atom peak (a quaternary-type nitrogen atom) having a peak top in the range of 401.5±0.3 eV and a full width at half maximum of 1.4 eV. and (4) an oxidized nitrogen atom peak (a peak derived from an oxidized nitrogen atom) having a peak top in the range of 402.5±0.3 eV and a full width at half maximum of 2.0 eV, the ratio of the area of ​​the quaternary nitrogen atom peak to the total area of ​​the four nitrogen atom peaks (i.e., the total area of ​​the pyridine-type nitrogen atom peak, the pyrrole / pyridone-type nitrogen atom peak, the quaternary nitrogen atom peak, and the oxidized nitrogen atom peak) obtained by peak separation into the above four nitrogen atom peaks (hereinafter referred to as "quaternary nitrogen ratio") may be 0.1% or more.

[0055] In this case, the quaternary nitrogen ratio of the present catalyst is, for example, preferably 1.0% or more, more preferably 2.0% or more, even more preferably 3.0% or more, even more preferably 4.0% or more, even more preferably 5.0% or more, even more preferably 6.0% or more, even more preferably 7.0% or more, even more preferably 8.0% or more, even more preferably 10.0% or more, even more preferably 12.0% or more, even more preferably 14.0% or more, even more preferably 16.0% or more, even more preferably 18.0% or more, and particularly preferably 20.0% or more.

[0056] The quaternary nitrogen ratio of the present catalyst may be, for example, 70.0% or less, 60.0% or less, 50.0% or less, 45.0% or less, 40.0% or less, 35.0% or less, or 30.0% or less. The quaternary nitrogen ratio of the present catalyst may be specified by any combination of any of the above-mentioned lower limit values ​​and any of the above-mentioned upper limit values.

[0057] Here, pyridine-type nitrogen atoms, pyrrole / pyridone-type nitrogen atoms, and oxidized nitrogen atoms are mainly present at edge sites of the carbon network plane contained in the carbon structure, whereas quaternary-type nitrogen atoms are present within the carbon network plane.

[0058] The proportion of quaternary nitrogen contributes to improving the catalytic activity and durability of the catalyst. That is, for example, an increase in the proportion of quaternary nitrogen in the carbon structure contributes to effectively improving the catalytic activity by increasing the electron density at the curved portions of the carbon network plane due to the quaternary nitrogen atoms doped into the carbon network plane contained in the carbon structure.

[0059] The catalyst may have a ratio of the area of ​​the pyridine-type nitrogen atom peak to the total area of ​​the four nitrogen atom peaks (1) to (4) obtained by peak separation of the N1s spectrum in the spectrum obtained by XPS (hereinafter referred to as the "pyridine-type nitrogen ratio") of 50.0% or less.

[0060] In this case, the pyridine nitrogen content of the catalyst is, for example, preferably 45.0% or less, more preferably 40.0% or less, even more preferably 35.0% or less, and particularly preferably 30.0% or less.

[0061] The pyridine-type nitrogen ratio of the present catalyst may be, for example, 1.0% or more, 3.0% or more, 5.0% or more, 7.0% or more, 9.0% or more, or 10.0% or more. The pyridine-type nitrogen ratio of the present catalyst may be specified by any combination of any of the above-mentioned lower limit values ​​and any of the above-mentioned upper limit values.

[0062] The catalyst may have a ratio of the area of ​​the pyrrole / pyridone type nitrogen atom peak to the total area of ​​the four nitrogen atom peaks (1) to (4) obtained by peak separation of the N1s spectrum in the spectrum obtained by XPS (hereinafter referred to as the "pyrrole / pyridone type nitrogen ratio") of 70.0% or less.

[0063] In this case, the pyrrole / pyridone type nitrogen ratio of the present catalyst may be, for example, 65.0% or less, 60.0% or less, 55.0% or less, 50.0% or less, 45.0% or less, 40.0% or less, or 35.0% or less.

[0064] The pyrrole / pyridone type nitrogen ratio of the present catalyst may be, for example, 1.0% or more, 5.0% or more, 10.0% or more, 15.0% or more, 20.0% or more, 25.0% or more, or 30.0% or more. The pyrrole / pyridone type nitrogen ratio of the present catalyst may be specified by any combination of any of the above-mentioned lower limit values ​​and any of the above-mentioned upper limit values.

[0065] The catalyst may have a ratio of the area of ​​the oxidized nitrogen atom peak to the total area of ​​the four nitrogen atom peaks (1) to (4), which is obtained by peak separation of the N1s spectrum in the spectrum obtained by XPS (hereinafter referred to as "oxidized nitrogen ratio") of 1.0% or more.

[0066] In this case, the proportion of oxidized nitrogen in the present catalyst is, for example, preferably 5.0% or more, more preferably 10.0% or more, even more preferably 15.0% or more, and particularly preferably 18.0% or more.

[0067] The oxidized nitrogen ratio of the present catalyst may be, for example, 50.0% or less, 45.0% or less, 40.0% or less, 35.0% or less, 30.0% or less, or 25.0% or less. The oxidized nitrogen ratio of the present catalyst may be specified by any combination of any of the above-mentioned lower limit values ​​and any of the above-mentioned upper limit values.

[0068] The carbon atom concentration of the present catalyst obtained by XPS is not particularly limited as long as the effects of the present invention can be obtained, but may be, for example, 50.0 (atomic %) or more, preferably 60.0 (atomic %) or more, more preferably 70.0 (atomic %) or more, still more preferably 75.0 (atomic %) or more, even more preferably 80.0 (atomic %) or more, and particularly preferably 85.0 (atomic %) or more.

[0069] The carbon atom concentration of the present catalyst obtained by XPS may be, for example, 99.0 (atomic%) or less, 98.0 (atomic%) or less, 97.0 (atomic%) or less, 96.0 (atomic%) or less, 95.0 (atomic%) or less, 94.0 (atomic%) or less, or 93.0 (atomic%) or less. The carbon atom concentration of the present catalyst obtained by XPS may be specified by any combination of any of the above-mentioned lower limit values ​​and any of the above-mentioned upper limit values.

[0070] The catalyst may contain oxygen atoms. In this case, the oxygen atom concentration of the catalyst obtained by XPS may be, for example, 1.0 (atomic %) or more, 2.0 (atomic %) or more, 3.0 (atomic %) or more, 4.0 (atomic %) or more, or 5.0 (atomic %) or more.

[0071] The oxygen atomic concentration of the catalyst obtained by XPS may be, for example, 35.0 (atomic%) or less, 30.0 (atomic%) or less, 25.0 (atomic%) or less, 20.0 (atomic%) or less, 15.0 (atomic%) or less, or 10.0 (atomic%) or less. The oxygen atomic concentration of the catalyst obtained by XPS may be specified by any combination of any of the above-mentioned lower limit values ​​and any of the above-mentioned upper limit values.

[0072] The BET specific surface area of ​​the catalyst obtained by the nitrogen adsorption method is not particularly limited as long as the effects of the present invention can be obtained. For example, ２ / g or more, and ２ / g or more is more preferable, and 200m ２ / g or more is more preferable, and 300m ２ / g or more is more preferable, and 400m ２ / g or more is more preferable, and 450m ２ / g or more is more preferable, and 500m ２ / g or more is more preferable, and 550m ２ It is particularly preferable that the SiO2 content is 1 / g or more.

[0073] The BET specific surface area of ​​the catalyst is, for example, 4000 m ２ / g or less, and ２ / g or less, and ２ / g or less, and ２ / g or less, and ２ / g or less, and ２ / g or less, and ２ / g or less, and ２ The BET specific surface area of ​​the present catalyst may be specified by any combination of any of the above-mentioned lower limit values ​​and any of the above-mentioned upper limit values.

[0074] The BET specific surface area contributes to improving the catalytic activity and durability of the present catalyst. That is, for example, an increase in the BET specific surface area improves the contact efficiency between the carbon structure contained in the carbon catalyst and the reactive active material, thereby contributing to improving the catalytic activity.

[0075] The present catalyst may contain a metal (hereinafter referred to as a "non-noble metal") other than a noble metal (i.e., ruthenium (Ru), palladium (Pd), rhodium (Rh), silver (Ag), osmium (Os), iridium (Ir), platinum (Pt), and gold (Au)).

[0076] The non-noble metal contained in the present catalyst is not particularly limited as long as the effects of the present invention can be obtained. For example, the non-noble metal may be a non-noble metal belonging to Groups 2 to 14 of the periodic table, preferably a non-noble metal belonging to Periods 3 to 5 of Groups 2 to 14 of the periodic table, and more preferably a non-noble metal belonging to Periods 3 to 4 of Groups 2 to 14 of the periodic table.

[0077] Specifically, the non-precious metal contained in the present catalyst is more preferably one or more selected from the group consisting of magnesium (Mg), aluminum (Al), calcium (Ca), titanium (Ti), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), yttrium (Y), zirconium (Zr), niobium (Nb), molybdenum (Mo), and tin (Sn), and particularly preferably one or more selected from the group consisting of Cu, Zn, and Sn.

[0078] The present catalyst may contain a non-precious metal derived from a raw material for carbonization in its production. That is, as described below, the production method of the present catalyst may include carbonization of a raw material containing a non-precious metal, and in this case, the present catalyst contains the non-precious metal due to the non-precious metal being contained in the raw material for carbonization.

[0079] Specifically, the catalyst contains a non-precious metal inside the skeleton that constitutes its porous structure. That is, even when the catalyst is a carbonized material produced by carbonization followed by a metal removal treatment (described later), the non-precious metal derived from the raw material for carbonization remains inside the skeleton of the catalyst. In this regard, the weight of the non-precious metal contained inside the skeleton of the catalyst may be greater than the weight of the non-precious metal contained on the surface of the skeleton of the catalyst.

[0080] The non-precious metals within the framework of the catalyst can be detected, for example, by subjecting the framework to a surface etching treatment and analyzing the cross section exposed by the etching treatment. That is, in this case, when one particle of the catalyst is etched, the non-precious metals are detected on the cross section of the particle exposed by the etching treatment. The non-precious metals contained in the catalyst can be detected, for example, by inductively coupled plasma (ICP) atomic emission spectrometry of the catalyst.

[0081] The content of non-precious metals in the present catalyst (when the present catalyst contains multiple types of non-precious metals, the total content of the multiple types of non-precious metals) is not particularly limited as long as the effects of the present invention are obtained, but may be, for example, 50 ppm or more, 100 ppm or more, 500 ppm or more, 1000 ppm or more, 5000 ppm or more, 10,000 ppm or more, 50,000 ppm or more, or 100,000 ppm or more.

[0082] The non-precious metal content of the catalyst may be, for example, 500,000 ppm or less, 400,000 ppm or less, 300,000 ppm or less, 200,000 ppm or less, 100,000 ppm or less, 50,000 ppm or less, or 30,000 ppm or less. The non-precious metal content of the catalyst may be specified by any combination of the above-mentioned lower limit value and any of the above-mentioned upper limit value. Note that 1 ppm means 0.0001 wt%. The non-precious metal content is measured by inductively coupled plasma (ICP) atomic emission spectroscopy.

[0083] The non-precious metal atomic concentration of the present catalyst obtained by XPS (when the present catalyst contains multiple types of non-precious metals, the total atomic concentration of the multiple types of non-precious metals) may be, for example, 0.001 (atomic %) or more, 0.005 (atomic %) or more, or 0.010 (atomic %) or more.

[0084] The non-noble metal atom concentration of the catalyst obtained by XPS may be, for example, 30.000 (atomic%) or less, 25.000 (atomic%) or less, 20.000 (atomic%) or less, 15.000 (atomic%) or less, 10.000 (atomic%) or less, 5.000 (atomic%) or less, 2.000 (atomic%) or less, 1.000 (atomic%) or less, 0.500 (atomic%) or less, 0.100 (atomic%) or less, 0.050 (atomic%) or less, 0.030 (atomic%) or less, or 0.020 (atomic%) or less. The non-noble metal atom concentration of the catalyst obtained by XPS may be specified by any combination of any of the above-mentioned lower limit values ​​and any of the above-mentioned upper limit values.

[0085] The non-precious metal contained in the present catalyst contributes to improving the catalytic activity of the present catalyst during its production process. That is, for example, when the present catalyst contains a non-precious metal derived from a raw material for carbonization, by performing the carbonization in the presence of the non-precious metal, a unique carbon structure containing catalytic active sites can be effectively formed.

[0086] However, the catalytic activity of this catalyst is thought to be mainly due to the catalytic active sites contained in the carbon structure rather than the non-precious metals derived from the raw material. This is supported by the fact that even when this catalyst, which contains non-precious metals derived from the raw material for carbonization, is subjected to a metal removal treatment to reduce the content of the non-precious metals, the catalytic activity of this catalyst after the metal removal treatment does not decrease significantly compared to that before the metal removal treatment.

[0087] The content of metals other than Mg, Al, Ca, Ti, Mn, Fe, Co, Ni, Cu, Zn, Y, Zr, Nb, Mo, and Sn in the present catalyst, the content of metals other than Fe, Cu, Zn, and Sn, or the content of metals other than Cu, Zn, and Sn may be, for example, 30,000 ppm or less, 25,000 ppm or less, 20,000 ppm or less, 15,000 ppm or less, 10,000 ppm or less, 5,000 ppm or less, 3,000 ppm or less, 2,000 ppm or less, 1,000 ppm or less, 500 ppm or less, 300 ppm or less, 200 ppm or less, 100 ppm or less, or 50 ppm or less. The non-noble metal content is obtained by inductively coupled plasma (ICP) optical emission spectroscopy.

[0088] The present catalyst may not contain a precious metal. That is, as described above, the present catalyst itself exhibits catalytic activity without supporting a precious metal, and therefore does not need to contain a precious metal. However, the present catalyst may also be used as a carbon support for supporting a metal catalyst such as a precious metal.

[0089] The method for producing the present catalyst is not particularly limited as long as it is a method that can obtain the present catalyst having the above-mentioned properties. For example, it is preferable that the method includes carbonizing a raw material containing an organic substance and subjecting the carbonized material obtained by the carbonization to a halogen introduction treatment.

[0090] The organic matter contained in the raw material is not particularly limited as long as it can be carbonized. The organic compound contained in the organic matter may be a polymer (e.g., a thermosetting resin and / or a thermoplastic resin) and / or an organic compound with a smaller molecular weight.

[0091] The organic substance is preferably a nitrogen-containing organic substance. The nitrogen-containing organic substance includes, for example, a nitrogen-containing organic compound. The nitrogen-containing organic compound is not particularly limited as long as it is an organic compound containing a nitrogen atom in its molecule. The content of nitrogen atoms in the nitrogen-containing organic compound is not particularly limited as long as the effects of the present invention can be obtained. For example, a nitrogen-containing organic compound whose nitrogen atom content is within a range suitable for obtaining the present catalyst having the above-mentioned properties can be appropriately selected and used.

[0092] Specific examples of organic substances include quinoxaline (for example, 2-hydroxyquinoxaline), phenanthroline (for example, 1,10 phenanthroline), alginate (for example, ammonium alginate), polyacrylonitrile, polyacrylonitrile-polyacrylic acid copolymer, polyacrylonitrile-polymethyl acrylate copolymer, polyacrylonitrile-polymethacrylic acid copolymer, polyacrylonitrile-polymethacrylic acid-polymethallylsulfonic acid copolymer, polyacrylonitrile-polymethyl methacrylate copolymer, pheno resin, polyfurfuryl alcohol, furan, furan resin, phenol formaldehyde resin, melamine, melamine resin, epoxy resin, nitrogen-containing chelate resin (for example, one or more selected from the group consisting of polyamine type, iminodiacetic acid type, aminophosphoric acid type, and aminomethylphosphonic acid type), polyamideimide resin, pyrrole, polypyrrole, polyvinylpyrrole, 3-methylpolypyrrole, acrylonitrile, polyvinylidene chloride, thiophene, oxazole, thiazole, pyrazole, vinylpyridine, polyvinylpyridine, pyridazine, Pyrimidine, piperazine, pyran, morpholine, imidazole, 1-methylimidazole, 2-methylimidazole, aniline, polyaniline, succinic acid dihydrazide, adipic acid dihydrazide, polysulfone, polyaminobismaleimide, polyimide, polyvinyl alcohol, polyvinyl butyral, benzimidazole, polybenzimidazole, polyamide, polyester, polylactic acid, polyether, polyether ether ketone, cellulose, carboxymethyl cellulose, lignin, chitin, chitosan, pitch, silk, wool, polyamide The organic solvent may be one or more selected from the group consisting of carboxylic acids, nucleic acids, DNA, RNA, hydrazine, hydrazide, urea, salen, polycarbazole, polybismaleimide, triazine, polyacrylic acid, polyacrylic acid ester, polymethacrylic acid ester, polymethacrylic acid, polyurethane, polyamidoamine, polycarbodiimide, naphthalene, naphthalene analogs, anthracene, anthracene analogs, hydroxybenzene, hydroxybenzene analogs, carbazole, quinoline, cyanuric acid, naphthoic acid, methylene blue, and phthalocyanine.

[0093] Carbonization is carried out by heating the raw material at a temperature at which the organic matter contained in the raw material is carbonized. The carbonization temperature is not particularly limited as long as it is a temperature at which the raw material is carbonized, and may be, for example, 400°C or higher, preferably 500°C or higher, more preferably 550°C or higher, even more preferably 600°C or higher, and particularly preferably 620°C or higher.

[0094] The carbonization temperature may be, for example, 3000°C or lower, preferably 2500°C or lower, more preferably 2000°C or lower, even more preferably 1500°C or lower, and particularly preferably 1200°C or lower. The carbonization temperature may be specified by any combination of any of the above-mentioned lower limit values ​​and any of the above-mentioned upper limit values. The rate of temperature rise up to the carbonization temperature is not particularly limited, and may be, for example, 0.5°C / min or higher and 300°C / min or lower. Carbonization is preferably carried out in an inert atmosphere such as a nitrogen atmosphere.

[0095] The halogen introduction treatment is a treatment for introducing halogen atoms into the carbon structure of the carbonized material obtained by carbonization. Specifically, the halogen introduction treatment is carried out, for example, by contacting the carbonized material with a halogen-containing gas while heating it. The content of the halogen gas in the halogen-containing gas is not particularly limited as long as the effect of the halogen introduction treatment is obtained, but for example, it is preferably 1 vol %, more preferably 5 vol % or more, and particularly preferably 10 vol %. The gas mixed with the halogen gas in the halogen-containing gas is not particularly limited as long as the effect of the halogen introduction treatment is obtained, but is preferably an inert gas (e.g., argon gas and / or nitrogen gas). The heating temperature in the halogen introduction treatment is not particularly limited as long as the effect of the halogen introduction treatment is obtained, but for example, it is preferably 100°C or higher, more preferably 300°C or higher, even more preferably 500°C or higher, and particularly preferably 600°C or higher.

[0096] The method for producing the catalyst of the present invention is preferably a method including, for example, carbonizing a raw material containing an organic substance and a non-precious metal, and subjecting the carbonized material obtained by the carbonization to a halogen introduction treatment. In this case, the method for producing the catalyst of the present invention may be a method including carbonizing a raw material containing an organic substance and a non-precious metal, subjecting the carbonized material obtained by the carbonization to a metal removal treatment, and subjecting the carbonized material after the metal removal treatment to a halogen introduction treatment. The metal removal treatment is a treatment that reduces the amount of non-precious metals derived from the raw material contained in the carbonized material. Specifically, the metal removal treatment is preferably, for example, an acid washing treatment and / or an electrolytic treatment.

[0097] The electrode according to this embodiment (hereinafter referred to as "the electrode") contains the catalyst. That is, the electrode may include, for example, an electrode substrate and the catalyst supported on the electrode substrate. The electrode is preferably a battery electrode. Specifically, the electrode is preferably an electrode of, for example, a fuel cell (e.g., a polymer electrolyte fuel cell, a microbial fuel cell), an air battery, a water electrolyzer (e.g., a polymer electrolyte water electrolyzer), a redox flow battery, or a halogen battery.

[0098] The electrode may be either a cathode or an anode, but is preferably a cathode, i.e., the electrode is the cathode or anode, preferably a cathode, of a fuel cell, air cell, water electrolyzer, redox flow battery, or halogen battery.

[0099] The battery according to this embodiment (hereinafter referred to as "this battery") includes this electrode. Specifically, this battery is preferably a fuel cell (e.g., a polymer electrolyte fuel cell, a microbial fuel cell), an air battery, a redox flow battery, or a halogen battery that includes this electrode. This battery preferably has a membrane electrode assembly (MEA) that includes this electrode.

[0100] The present battery is a battery having the present electrode as a cathode or an anode, preferably a battery having the present electrode as a cathode. That is, the present battery is a fuel cell, air battery, redox flow battery, or halogen battery having the present electrode as a cathode or an anode, preferably a fuel cell, air battery, redox flow battery, or halogen battery having the present electrode as a cathode.

[0101] Next, a specific example according to this embodiment will be described.

[0102] [Example 1] 1.0 g of 2-hydroxyquinoxaline was dissolved in 20 mL of acetone, and tin (II) chloride (SnCl ２ 25.95 g of ) was added and mixed in a mortar to make a uniform mixture, thereby obtaining a raw material for carbonization.

[0103] The obtained raw material was then carbonized by placing it in an HB tube, heating it in a silicon furnace in a nitrogen atmosphere at a rate of 50°C / min up to 650°C, and holding the raw material at 650°C for 30 minutes.

[0104] Next, the carbonized material obtained by carbonization was subjected to a pulverization treatment. That is, silicon nitride balls with a diameter of 10 mm were set in a planetary ball mill (P-7, manufactured by Fritsch Japan Co., Ltd.), and the carbonized material was pulverized by the planetary ball mill.

[0105] Furthermore, the carbonized material was subjected to a metal removal treatment. Specifically, 100 mL of concentrated hydrochloric acid was added to the pulverized carbonized material, and the mixture was heated to 80°C and stirred for 2 hours. Thereafter, the solution containing the carbonized material was filtered using a filter membrane and washed with distilled water until the filtrate became neutral. The recovered carbonized material was vacuum dried.

[0106] Thereafter, the carbonized material was subjected to a heat treatment. That is, the carbonized material from which the metal removal treatment had been performed was placed in a quartz tube, and the heat treatment was performed by heating in an image furnace in a nitrogen atmosphere and maintaining the temperature at 1000°C for 30 minutes, thereby obtaining a carbon catalyst.

[0107] Furthermore, the carbon catalyst was subjected to a halogen introduction treatment. That is, the carbon catalyst obtained as described above was placed in a quartz tube, and the temperature was increased to 600°C at a temperature increase rate of 50°C / min in a chlorine atmosphere (a mixed gas of 10% by volume of chlorine gas and 90% by volume of argon gas) in an image furnace, and the carbon catalyst was maintained at 600°C for 30 minutes.

[0108] Thereafter, while the temperature was maintained at 600° C., the chlorine atmosphere was switched to an argon atmosphere (100% by volume of argon gas), and the carbon catalyst was maintained in the argon atmosphere at 600° C. for 10 minutes. In this way, the carbon catalyst of Example 1 was obtained.

[0109] [Example 2] As for the raw material for carbonization, 1.0 g of 1,10-phenanthroline was used instead of 2-hydroxyquinoxaline, and tin (II) chloride (SnCl ２ A carbon catalyst was obtained in the same manner as in Example 1 above, except that the amount of 21.04 g of 2-methyl-2-propanol was changed to 21.04 g.

[0110] Furthermore, the carbon catalyst thus obtained was subjected to the same halogen introduction treatment as in Example 1 above, thereby obtaining a carbon catalyst of Example 2.

[0111] [Example 3] As for the raw material for carbonization, 5.0 g of ammonium alginate was used instead of 2-hydroxyquinoxaline, and tin (II) chloride (SnCl ２ A carbon catalyst was obtained in the same manner as in Example 1 above, except that the amount of 2.2g ...

[0112] Furthermore, the carbon catalyst thus obtained was subjected to the same halogen introduction treatment as in Example 1 above, thereby obtaining the carbon catalyst of Example 3.

[0113] [Example 4] For the raw material of carbonization, tin (II) chloride (SnCl ２ ) instead of zinc (II) chloride (ZnCl ２ A carbon catalyst was obtained in the same manner as in Example 3 above, except that 3.53 g of 1,2-dichloro-2,4 ...

[0114] Furthermore, the carbon catalyst thus obtained was subjected to the same halogen introduction treatment as in Example 1 above, thereby obtaining a carbon catalyst of Example 4.

[0115] [Example C1] 0.5 g of polyacrylonitrile was dissolved in 200 mL of dimethylformamide, and copper (II) chloride (CuCl ２ 25.34 g of methyl cellulose was added to prepare a homogeneous solution. This solution was dried in vacuum at 80° C. for 24 hours to obtain a raw material for carbonization.

[0116] The obtained raw material was then placed in an HB tube, heated to 800°C at a rate of 50°C / min in a nitrogen atmosphere in a silicon furnace, and held at 800°C for 30 minutes, thereby carbonizing the raw material.

[0117] Next, the carbonized material obtained by carbonization was subjected to a pulverization treatment. That is, silicon nitride balls with a diameter of 10 mm were set in a planetary ball mill (P-7, manufactured by Fritsch Japan Co., Ltd.), and the carbonized material was pulverized by the planetary ball mill.

[0118] Furthermore, the carbonized material was subjected to a metal removal treatment. Specifically, 100 mL of concentrated nitric acid was added to the pulverized carbonized material, and the mixture was heated to 80°C and stirred for 2 hours. Thereafter, the solution containing the carbonized material was filtered using a filter membrane and washed with distilled water until the filtrate became neutral. The recovered carbonized material was vacuum dried.

[0119] Thereafter, the carbonized material was subjected to a heat treatment. That is, the carbonized material that had been subjected to the metal removal treatment was placed in a quartz tube, and the heat treatment was carried out by heating in an image furnace in a nitrogen atmosphere and maintaining the temperature at 800°C for 30 minutes, thereby obtaining a carbon catalyst.

[0120] Furthermore, the carbon catalyst thus obtained was subjected to the same halogen introduction treatment as in Example 1 above, to obtain the carbon catalyst of Example C1.

[0121] [Example C2] 3.0 g of phthalocyanine was dispersed in 30 mL of acetone, and copper (II) chloride (CuCl ２ ) 15.68 g and iron (III) chloride hexahydrate (FeCl ３ ・6H ２ 0) was added and mixed in a mortar to be uniform, to obtain a raw material for carbonization.

[0122] Then, in the same manner as in Example 1 described above, the raw material was carbonized, and the carbonized material obtained by the carbonization was pulverized.

[0123] Furthermore, the carbonized material was subjected to a metal removal treatment. Specifically, 100 mL of concentrated nitric acid was added to the pulverized carbonized material, and the mixture was heated to 80°C and stirred for 2 hours. Thereafter, the solution containing the carbonized material was filtered using a filter membrane and washed with distilled water until the filtrate became neutral. The recovered carbonized material was vacuum dried.

[0124] Thereafter, the carbonized material was subjected to a heat treatment. That is, the carbonized material that had been subjected to the metal removal treatment was placed in a quartz tube, and the heat treatment was carried out by heating in an image furnace in a nitrogen atmosphere and maintaining the temperature at 600°C for 30 minutes, thereby obtaining a carbon catalyst.

[0125] Furthermore, the carbon catalyst thus obtained was subjected to the same halogen introduction treatment as in Example 1 above, to obtain the carbon catalyst of Example C2.

[0126] [Example C3] 2.0 g of phthalocyanine was dispersed in 20 mL of acetone, and tin (II) chloride (SnCl ２ ) was added and mixed in a mortar to be uniform, to obtain a raw material for carbonization.

[0127] Then, in the same manner as in Example 1 described above, the raw material was carbonized, the carbonized material obtained by the carbonization was pulverized, and the metal was removed from the pulverized carbonized material.

[0128] Thereafter, the carbonized material was subjected to a heat treatment. That is, the carbonized material that had been subjected to the metal removal treatment was placed in a quartz tube, and the heat treatment was carried out by heating in an image furnace in a nitrogen atmosphere and maintaining the temperature at 600°C for 30 minutes, thereby obtaining a carbon catalyst.

[0129] Furthermore, the carbon catalyst thus obtained was subjected to the same halogen introduction treatment as in Example 1 above, to obtain the carbon catalyst of Example C3.

[0130] [Powder X-ray Diffraction] Powder X-ray diffraction (XRD) measurement of the carbon catalyst was carried out using an X-ray diffractometer (XRD-6100, manufactured by Rigaku Corporation). CuKα rays were used as incident X-rays, the voltage and current applied to the X-ray tube were set to 40 kV and 15 mA, respectively, and the measurement angle range (2θ) was set to the range of 5° to 90°. The crystallite sizes Lc and La were obtained by analyzing the powder X-ray diffraction diagram obtained by the XRD measurement of the carbon catalyst as follows.

[0131] That is, when a carbon catalyst has a stacked structure of carbon network planes extending in the c-axis direction among crystallites constituting the carbon network planes, a diffraction peak f f , which is a (002) diffraction line of carbon and has a peak top at a diffraction angle (2θ) of around 26° (for example, within a range of 24.0° or more and 26.5° or less), is formed in an X-ray diffraction pattern of the carbon catalyst using CuKα rays. ００２ In this embodiment, the diffraction peak f ００２ was defined as a diffraction peak whose diffraction angle (2θ) was 25.0° or more and 26.5° or less and whose full width at half maximum was 0.05° or more and 20° or less.

[0132] And this f ００２ The crystallite size Lc was calculated by analyzing the obtained X-ray diffraction diagram. That is, first, the Lorentz factor (L), the polarization factor (P), the absorption factor (A), and the carbon atomic scattering factor (f ｃ After intensity correction for the α-value (α), background correction was performed. Specifically, the correction factor was calculated by the following formula: correction factor = L*P*A*f ｃ ２ Intensity correction was performed by dividing the diffraction intensity at each measurement angle by . The method for background correction is not particularly limited as long as it can align the baseline, but in this example, background correction was performed by finding an approximate line (linear function) from the data in the section from the start of the peak to the end of the peak, and subtracting the value of the approximate line from each diffraction intensity.

[0133] Next, in the obtained corrected X-ray diffraction pattern, the diffraction peak f ００２The crystallite size Lc was calculated by substituting the Bragg angle and full width at half maximum into the following Scherrer formula: Lc = Kλ / (β cos θ), where K is the Scherrer constant (0.94), λ is the wavelength of CuKα radiation (0.15418 nm), β is the full width at half maximum (radian), and θ is the Bragg angle (radian).

[0134] Furthermore, when a carbon catalyst has a structure in which, among the crystallites constituting the carbon network plane, hexagonal carbon network planes extending in the a-axis direction are connected, in an X-ray diffraction diagram of the carbon catalyst using CuKα rays, a diffraction peak f which is a (10) diffraction line of carbon and has a peak top at a diffraction angle (2θ) of around 43° (for example, in a range of 35° or more and 60° or less) is formed. １０ appears.

[0135] Here, when the carbon catalyst contains iron, a diffraction peak derived from iron may also appear at a diffraction angle (2θ) of about 43°. That is, in this case, the diffraction peak derived from the carbon structure includes the (10) diffraction peak of carbon and a diffraction peak f Ｆｅ Therefore, for the carbon catalyst containing iron, the diffraction peak at a diffraction angle (2θ) of about 43° is separated into two diffraction peaks, namely, f １０ and f Ｆｅ and separated into

[0136] Peak separation was performed by approximating overlapping diffraction peaks by superimposing Voigt-type fundamental waveforms. Fitting was performed on the background-corrected X-ray diffraction pattern by optimizing the peak intensity, full width at half maximum, and peak position of each component of the Voigt function as parameters. The background correction method is not particularly limited as long as it can align the baseline. In this example, background correction was performed by determining an approximate straight line (linear function) from the data in the section from the peak start to the peak end, and subtracting the value of the approximate straight line from each diffraction intensity.

[0137] More specifically, this peak separation was performed by the following procedure: In the X-ray diffraction pattern using CuKα radiation after the background correction, a diffraction peak having a peak top at a diffraction angle 2θ of approximately 43° was approximated by superimposing Voigt-type fundamental waveforms, and the peak intensity, full width at half maximum, and peak position were optimized, and each of the two overlapping diffraction peaks included in the diffraction peak was subjected to curve fitting, thereby performing peak separation.

[0138] The curve fitting was performed so that the sum of squared residuals was minimized. Here, the squared residuals are the squares of the residuals at each measured diffraction angle, and the sum of squared residuals is the sum of these squared residuals. The residual is the intensity of the diffraction peak having a peak top at a diffraction angle 2θ of around 43° in the X-ray diffraction pattern using CuKα radiation, and the intensity of the two diffraction peaks f obtained by separating them. １０ and f Ｆｅ is the difference between the sum of the intensities of

[0139] For the iron-containing carbon catalyst, such peak separation results in two diffraction peaks f １０ and f Ｆｅ Specifically, the diffraction peak f １０ was defined as a diffraction peak having a diffraction angle (2θ) of 43.5°±1.0° and a full width at half maximum of 7.5°±6.5°. Ｆｅ was defined as the diffraction peak whose diffraction angle (2θ) was 44.0°±1.0° and whose full width at half maximum was 0.5°±0.3°.

[0140] In addition, for the carbon catalyst that does not contain iron, in the X-ray diffraction diagram of the carbon catalyst using CuKα rays, a diffraction peak f １０ was defined as the diffraction peak whose diffraction angle (2θ) was 43.5°±1.0° and whose full width at half maximum was 7.5°±6.5°.

[0141] The obtained diffraction peak f １０ The crystallite size La was calculated by analyzing the diffraction peak f １０The Bragg angle and full width at half maximum of the spectrum were substituted into the following Scherrer equation: La = Kλ / (β cos θ), where K is the Scherrer constant (0.94), λ is the wavelength of CuKα radiation (0.15418 nm), β is the full width at half maximum (radian), and θ is the Bragg angle (radian).

[0142] [Temperature Programmed Desorption Analysis] Temperature programmed desorption analysis (high-temperature TPD) of the carbon catalyst of each example was performed using a temperature programmed desorption analyzer (high-temperature TPD apparatus) capable of heating up to 1600° C. The high-temperature TPD apparatus is an apparatus capable of heating a graphite crucible, which is a heated body, to a high temperature of 1600° C. or higher by high-frequency electromagnetic induction heating. Details of this high-temperature TPD device are described in Carbon magazine (Takafumi Ishi, SuSumu Kashihara, Yasuto Hoshikawa, Jun-ichi Ozaki, Naokatsu Kannari, Kazuki Takai, Toshiaki Enoki, Takashi Kyotoni, Carbon, Volume 80, December 2014, Pages 135-145).

[0143] A carbon catalyst was placed in this high-temperature TPD device, and 5 × 10 －５ The carbon catalyst was heated under a high vacuum of 100 Pa or less, and the desorbed gas was measured with a quadrupole mass spectrometer (QMS).

[0144] Specifically, 1 mg of the carbon catalyst was first filled into a graphite crucible and set in a quartz reaction tube attached to a high-temperature TPD device. Next, the inside of the device was evacuated with a turbomolecular pump until the pressure reached 5×10. －５ After evacuation to a pressure of 0.01 Pa, the temperature was increased from room temperature to 1600°C at a rate of 10°C / min. During this temperature increase, desorbed gas was detected, and the correlation between temperature (horizontal axis) and detected intensity (vertical axis) was recorded. The amount of desorbed gas was then calculated. That is, the integrated value of the detected intensity (detected intensity area) of the gas from room temperature, where the heat treatment was started, to the temperature (1600°C) to be quantified was calculated.

[0145] On the other hand, a calibration curve showing the correlation between the amount of gas desorbed and the detection intensity area was created using a predetermined amount of standard gas. When analyzing the gas desorbed from the sample by QMS, the gas species with the same mass (CO, N for mass number 28) contained in the desorbed gas were analyzed. ２ , C ２ H ４ In order to strictly distinguish between various gas species (H ２ , H ２ O, CO, CO ２ , N ２ , HCN, O ２ , C.H. ４ , C ２ H ６ , C ３ H ６ , C ３ H ８ ) and examined the fragment intensity ratio, which was used for the qualitative characterization of the desorbed gas. Then, based on the detection intensity area obtained by the measurement, the calibration curve, and the fragment intensity ratio, the amount of gas desorbed (released) from the carbon catalyst was quantified. Furthermore, in order to confirm the validity of the created calibration curve, measurements were performed on Ketjen Black EC600JD (Lion Specialty Chemicals Co. Ltd.), and it was confirmed that the amount of edge hydrogen was within the range of 1000 μmol / g to 1500 μmol / g.

[0146] Here, the actual size of the carbon net planes constituting the carbon can be evaluated from the average carbon net plane size L obtained from the amount of carbon edge sites. In this embodiment, the total amount of carbon edge sites was calculated from the results of quantifying the desorbed gas in high-temperature TPD of the carbon catalyst, and the average carbon net plane size L obtained from this amount was calculated using the coronene model shown in FIG. 1. a in the formula shown in FIG. ０ represents the lattice constant of 0.2461 nm in the a-axis direction of graphite crystal.

[0147] Furthermore, it is known that phenolic hydroxyl groups among oxygen-containing compounds decompose to carbon monoxide upon heating, leaving hydrogen atoms derived from the hydroxyl groups at carbon edge sites. Therefore, the amount of hydrogen determined by high-temperature TPD may include the contribution of hydrogen derived from the phenolic hydroxyl groups.

[0148] In addition, both ether (-O-) and phenolic hydroxyl group (-OH) are functional groups that are eliminated as CO at around 700°C. After the phenolic hydroxyl group is eliminated as CO, H remains at the edge site. Therefore, for the phenolic hydroxyl group, after CO is eliminated, H is released at a temperature of 1000°C or higher. ２ In addition, the phenolic hydroxyl group can release two types of gases (CO and H) from one functional group. ２ It is not possible to distinguish between ethers and phenolic hydroxyl groups based on the CO elimination observed in TPD analysis.

[0149] Therefore, in order to accurately calculate the total amount of edge sites, it is necessary to consider the ether and phenolic hydroxyl groups. Therefore, it is assumed that the ether (-O-) is eliminated as CO in the high-temperature TPD. On the other hand, the phenolic hydroxyl group (-OH) is actually CO and H. ２ However, if both gases are considered at the same time, the number of edge sites will be overestimated. Therefore, the phenolic hydroxyl group (-OH) is H ２ From the following two equations, the total amount of edge sites of the carbon catalyst (N ｅｄｇｅ ) was calculated.

[0150] That is, the lower limit N of the total amount of edge sites ｅｄｇｅ (Min) was calculated by the following formula: N ｅｄｇｅ (Min) [μmol / g]=CO ２ [μmol / g] + H ２ [μmol / g]×2+N ２ [μmol / g] × 2 + HCN [μmol / g] × 2. In addition, the upper limit of the total amount of edge sites N ｅｄｇｅ (Max) was calculated by the following formula: N ｅｄｇｅ (Max) [μmol / g] = CO [μmol / g] + CO ２ [μmol / g] + H ２ [μmol / g]×2+N ２ [μmol / g] × 2 + HCN [μmol / g] × 2. Note that CO [μmol / g] and CO ２ [μmol / g], H ２[μmol / g], N ２ [μmol / g] and HCN [μmol / g] are the amounts of desorbed gases of carbon monoxide, carbon dioxide, hydrogen, nitrogen, and hydrogen cyanide, respectively, determined by high-temperature TPD.

[0151] On the other hand, the average carbon lattice plane size L is calculated by the following formula using the atomic weight of carbon atoms of 12 g / mol and the lattice constant of the graphite crystal in the a-axis direction of 0.2461 nm: L [nm] = 2 × 1 / 12 × 0.2461 / N ｅｄｇｅ [mol / g]. Here, the maximum value of L, "L(Max)", and the minimum value of L, "L(Min)", are calculated by the following two formulas: "L(Max)" [nm] = 2 × 1 / 12 × 0.2461 / N ｅｄｇｅ (Min) [mol / g];, "L (Min)" [nm] = 2 x 1 / 12 x 0.2461 / N ｅｄｇｅ (Max) [mol / g].

[0152] As described above, because it is difficult to separate the ether and the phenolic hydroxyl group, two values, a maximum value and a minimum value, are calculated for the average carbon network surface size L. However, "L(Max)" is the value when only phenolic hydroxyl groups are present, and "L(Min)" is the value when only ethers are present. However, in an actual carbon material, it is unlikely that only one of these two groups will be present. Therefore, in this embodiment, the average carbon network surface size L of the carbon catalyst is defined as "L(av.)," the median value between "L(Max)" and "L(Min)." That is, "L(av.)" was calculated by dividing the sum of "L(Min)," which was obtained as the minimum possible value of the average carbon network surface size L, and "L(Max)," which was obtained as the maximum possible value, by 2. Then, this "L(av.)" was obtained as the average carbon network surface size L of the carbon catalyst.

[0153] [X-ray Photoelectron Spectroscopy (XPS)] An X-ray photoelectron spectrometer (AXIS NOVA, manufactured by KRATOS) was used to measure photoelectron spectra from the core levels of carbon atoms, nitrogen atoms, oxygen atoms, chlorine atoms, and raw material-derived metal atoms (metal atoms contained in the carbonized raw material used to produce the carbon catalyst) on the surface of the carbon catalyst of each example. AlKα rays (10 mA, 15 kV, pass energy 40 eV) were used as the X-ray source. In the obtained photoelectron spectra, the binding energy was corrected so that the peak top of the C1s peak derived from the carbon is orbital was located at 284.5 eV.

[0154] In the XPS wide scan analysis, the atomic concentrations (atomic %) of carbon atoms, nitrogen atoms, oxygen atoms, chlorine atoms, and metal atoms derived from the raw materials on the surface of the carbon catalyst were determined from the peak areas and detection sensitivity coefficients in the photoelectron spectrum. The N / C ratio was calculated by dividing the nitrogen atomic concentration (atomic %) by the carbon atom concentration (atomic %). Furthermore, the Cl / C ratio, which is the halogen / C ratio, was calculated by dividing the chlorine atomic concentration (atomic %) by the carbon atom concentration (atomic %). The atomic concentrations (atomic %) were calculated assuming that the carbon catalyst contained carbon atoms, nitrogen atoms, oxygen atoms, chlorine atoms, and metal atoms derived from the raw materials. The background in the quantitative calculation was determined by the Shirley method.

[0155] Furthermore, peak separation of the N1s spectrum was performed on the obtained XPS spectrum. That is, the N1s spectrum having a peak top in the range of 389 eV to 410 eV was separated into (1) a peak having a peak top in the range of 398.5±0.3 eV and a full width at half maximum of 1.4 eV (pyridine-type nitrogen atom peak), (2) a peak having a peak top in the range of 400.5±0.3 eV and a full width at half maximum of 1.4 eV (pyrrole-pyridone-type nitrogen atom peak), (3) a peak having a peak top in the range of 401.5±0.3 eV and a full width at half maximum of 1.4 eV (quaternary-type nitrogen atom peak), and (4) a peak having a peak top in the range of 402.5±0.3 eV and a full width at half maximum of 2.0 eV (oxidized nitrogen atom peak).

[0156] Specifically, the N1s spectrum was separated by approximating the overlapping peaks with a superposition of Gaussian-Lorentzian fundamental waveforms. For the spectrum that underwent energy value correction and intensity correction (described below), the peak intensities and peak positions of the Gaussian-Lorentzian functions for each component were optimized as parameters, and the four overlapping peaks contained in the N1s spectrum were curve-fitted to separate the peaks. The curve fitting was performed to minimize the sum of squared residuals. Here, the squared residual is the square of the residual at each measured energy value, and the sum of squared residuals is the sum of these squared residuals. The residual is the difference between the intensity of the N1s spectrum in the corrected spectrum and the sum of the intensities of the four separated peaks.

[0157] Regarding the correction, first, the energy value was corrected for the XPS spectrum obtained by XPS measurement. The measurement results of carbon atoms derived from C1s were used for the energy value correction. When the normal value (284.5 eV) of the peak top of the C1s peak deviated from the measured peak top of the C1s peak, the measured C1s peak value was subtracted from the normal value, and the obtained value was added to the binding energy value of the N1s spectrum. Next, intensity correction was performed. The intensity correction was performed by subtracting the background intensity determined by the Shirley method from the intensity of the spectrum obtained by the energy value correction. Peak separation was performed using the spectrum obtained by such correction.

[0158] The ratio (%) of the area of ​​each peak to the total area of ​​the four peaks obtained by peak separation, i.e., the pyridine nitrogen peak, the pyrrole / pyridone nitrogen peak, the quaternary nitrogen peak, and the oxidized nitrogen peak, was then calculated.

[0159] [Specific Surface Area] The specific surface area of ​​the carbon catalyst of each example was measured by a nitrogen adsorption method using a specific surface area / pore distribution measuring device (BELSORP MINI X, manufactured by Microtrac BEL Co., Ltd.). That is, first, 0.03 g of the carbon catalyst was heated at 200° C. and 6.7×10 －２The carbon catalyst was held at 77 Pa for 2 hours to remove moisture adsorbed on the carbon catalyst. Next, a nitrogen adsorption isotherm at 77 K was obtained by the BET method. This nitrogen adsorption isotherm at 77 K was obtained by measuring the change in the amount of nitrogen adsorbed on the carbon catalyst with the change in the pressure of nitrogen gas at a temperature of 77 K. Then, the BET specific surface area (m ２ / g).

[0160] [Evaluation of Catalytic Activity and Durability] The catalytic activity of the carbon catalyst was evaluated using a rotating ring-disk electrode apparatus (RRDE-3A rotating ring-disk electrode apparatus ver. 1.2, manufactured by BAS Inc.) and a dual electrochemical analyzer (CHI700C, manufactured by ALS Corporation).

[0161] That is, first, a three-electrode rotating ring-disk electrode device having a working electrode containing a carbon catalyst was fabricated. Specifically, 5 mg of the carbon catalyst, 50 μL of 5% Nafion® (manufactured by Sigma-Aldrich, Nafion perfluorinated ion exchange resin, 5% solution (product number: 510211)), 400 μL of water, and 100 μL of isopropyl alcohol were mixed to prepare a slurry. Next, this slurry was subjected to ultrasonic treatment for 10 minutes, and then to homogenization for 2 minutes. The obtained slurry was then mixed with a 1000-kJ / cm2 electrode to prepare a 1000-kJ / cm2 electrode with a carbon catalyst content of 0.2 mg / cm2 per unit area. ２ The solution was applied to a working electrode (RRDE-3A ring-disk electrode, carbon ring-gold disk electrode, disk diameter 4 mm, manufactured by BAS Inc.) so that the solution satisfies the following formula: and then dried, thereby producing a working electrode on which the carbon catalyst was supported.

[0162] A carbon electrode (glass-like carbon round rod, φ2 mm × 100 mm, manufactured by BAS Co., Ltd.) was used as the counter electrode, and a reversible hydrogen electrode (RHE) (reservoir-type reversible hydrogen electrode, manufactured by EC Frontier Co., Ltd.) was used as the reference electrode. In this way, a rotating ring-disk electrode device was obtained, which had a working electrode containing a carbon catalyst, a carbon electrode as the counter electrode, and a reversible hydrogen electrode (RHE) as the reference electrode. A 0.05 M aqueous sulfuric acid solution was used as the electrolyte.

[0163] Then, the catalytic activity of the carbon catalyst was measured using the rotating ring-disk electrode device. That is, the catalytic activity was measured by linear sweep voltammetry (N ２ -LSV) and linear sweep voltammetry under oxygen atmosphere (O ２ -LSV) and were carried out.

[0164] N ２ In the LSV, nitrogen bubbling was first performed for 10 minutes to remove oxygen from the electrolyte. Then, the electrode was rotated at a rotation speed of 1600 rpm, and the current density was recorded as a function of potential when the potential was swept at a sweep rate of 20 mV / sec (N ２ -LSV function).

[0165] O ２ In -LSV, first, the above N ２ After the LSV, oxygen bubbling was performed for 10 minutes to fill the electrolyte with saturated oxygen. Then, the electrode was rotated at a rotation speed of 1600 rpm, and the current density was recorded as a function of potential when the potential was swept at a sweep rate of 20 mV / sec (O ２ -LSV function).

[0166] Then, the O obtained as described above ２ -LSV function to N ２ The oxygen reduction voltammogram was obtained by subtracting the -LSV function. In the obtained oxygen reduction voltammogram, the values ​​were assigned signs so that the reduction current was negative and the oxidation current was positive.

[0167] From the oxygen reduction voltammogram thus obtained, an index showing the catalytic activity of the carbon catalyst itself was calculated as −10 μA / cm ２ The voltage when the reduction current flows (oxygen reduction onset potential EO ２ ) (V vs. NHE) was recorded.

[0168] The durability of the carbon catalyst was also evaluated using a rotating ring-disk electrode apparatus and a dual electrochemical analyzer. That is, first, an oxygen reduction voltammogram was obtained in the same manner as in the evaluation of catalytic activity described above. Then, from the obtained oxygen reduction voltammogram, the current density (current density before degradation) (mA / cm) at 0.3 V (vs. NHE) was calculated as an index showing the amount of catalytic active sites of the carbon catalyst before the accelerated degradation test. ２ ) was recorded.

[0169] Subsequently, an accelerated degradation test was carried out using the working electrode used for the measurement of the pre-degradation current density described above: cyclic voltammetry was carried out in a range of 1.0 V to 1.5 V at 0.5 V / s for 100 cycles in a nitrogen atmosphere using a three-electrode rotating ring-disk electrode device (start-stop test).

[0170] Furthermore, after the start-stop test, nitrogen bubbling was performed for 10 minutes to remove oxygen from the electrolyte, and an oxygen reduction voltammogram was obtained in the same manner as in the measurement of the current density before degradation described above. From the obtained oxygen reduction voltammogram, the current density (current density after degradation) (mA / cm) at 0.3 V (vs. NHE) was determined as an index showing the amount of catalytic active sites of the carbon catalyst after the accelerated degradation test. ２ The current density after degradation thus obtained was divided by the current density before degradation, and the obtained value was multiplied by 100 to calculate durability (%).

[0171] [Results] Figure 2 shows the results of evaluating the characteristics of the carbon catalysts of each example. As shown in Figure 2, the catalytic activity (E Ｏ２ The catalytic activity (V vs. NHE) was higher than that of the carbon catalysts of Examples C2 and C3. Among them, the catalytic activities of the carbon catalysts of Examples 2 to 4 were higher than those of the carbon catalysts of Examples C1 to C3, and the carbon catalyst of Example 2 in particular had a significantly higher catalytic activity.

[0172] Furthermore, the durability (%) of the carbon catalysts of Examples 1 to 4 was significantly higher than that of the carbon catalysts of Examples C1 to C3. That is, the carbon catalysts of Examples 1 to 4 had both high catalytic activity and high durability.

[0173] The carbon catalysts of Examples 1 to 4 had significantly larger L / La ratios than those of the carbon catalysts of Examples C1 to C3. The crystallite sizes La of the carbon catalysts of Examples 1 to 4 were not significantly different from those of the carbon catalysts of Examples C1 to C3. In contrast, the average carbon mesh plane sizes L of the carbon catalysts of Examples 1 to 4 were significantly larger than those of the carbon catalysts of Examples C1 to C3. The crystallite sizes Lc of the carbon catalysts of Examples 1 to 4 were not significantly different from those of the carbon catalysts of Examples C1 to C3. The BET specific surface area of ​​the carbon catalyst of Example C1 was significantly larger, and that of the carbon catalyst of Example 1 was the smallest.

[0174] The carbon atom concentration (C (atm %)), oxygen atom concentration (O (atm %)), and metal atom concentration (Metal (atm %)) measured by XPS were not significantly different between the carbon catalysts of Examples 1 to 4 and the carbon catalysts of Examples C1 to C3.

[0175] In contrast, the chlorine atom concentrations (Cl (atm %)) of the carbon catalysts of Examples 1 to 4 were lower than those of the carbon catalysts of Examples C1 to C3. In this regard, it is considered that the carbon structures included in the carbon catalysts of Examples 1 to 4 have larger average carbon network plane sizes L and fewer edge sites of the carbon network planes than those of the carbon catalysts of Examples C1 to C3, and therefore the amounts of chlorine atoms introduced into the edge sites of the carbon catalysts of Examples 1 to 4 were also lower than those of the carbon catalysts of Examples C1 to C3.

[0176] The nitrogen atom concentrations (N (atm %)) of the carbon catalysts of Examples 1 to 4 were lower than those of the carbon catalysts of Examples C1 to C3. This difference was considered to be due to differences in the carbonization temperature during production of the carbon catalysts and the amounts of nitrogen atoms contained in the carbonization raw materials used in the production.

[0177] As described above, the N / C ratio and the Cl / C ratio of the carbon catalysts of Examples 1 to 4 were smaller than those of the carbon catalysts of Examples C1 to C3, due to the fact that the nitrogen atom concentrations (N (atm %)) and chlorine atom concentrations (Cl (atm %)) of the carbon catalysts of Examples 1 to 4 were small.

[0178] Regarding the types of nitrogen atoms contained in the carbon catalysts, the carbon catalysts of Examples 1 to 4 contained quaternary nitrogen atoms, whereas the carbon catalysts of Examples C1 to C3 did not contain quaternary nitrogen atoms. Specifically, the quaternary nitrogen proportion ("Quaternary proportion (%)" in the figure), which is the ratio of the quaternary nitrogen atom concentration (atm %) to the nitrogen atom concentration (total nitrogen atom concentration) (N (atm %)) of the carbon catalysts of Examples 1 to 4, was 7.0% or more.

[0179] On the other hand, the pyridine-type nitrogen ratio ("Pyridine ratio (%)" in the figure), which is the ratio of the pyridine-type nitrogen atom concentration (atm %) to the nitrogen atom concentration (N (atm %)), of the carbon catalysts of Examples 1 to 4 was smaller than that of the carbon catalysts of Examples C1 to C3.

[0180] The difference in the proportion of quaternary nitrogen atoms and the proportion of pyridine nitrogen atoms was considered to be due to the fact that the carbon structures contained in the carbon catalysts of Examples 1 to 4 had relatively large L / La ratios.

Claims

1. A carbon catalyst in which the L / La ratio, which is the ratio of the average carbon net plane size L obtained by thermal desorption analysis capable of heating up to 1600°C to the crystallite size La obtained from a diffraction peak at a diffraction angle (2θ) of about 43° in an X-ray diffraction pattern obtained by powder X-ray diffraction using CuKα rays, is 18 or more, and the ratio of the halogen atom concentration (atomic %) to the carbon atom concentration (atomic %) obtained by X-ray photoelectron spectroscopy is 0.0005 or more.

2. The carbon catalyst according to claim 1, wherein the average carbon net plane size L is 5 nm or more.

3. The carbon catalyst according to claim 1, wherein the crystallite size La is 10.00 nm or less.

4. The carbon catalyst according to claim 1, containing a nitrogen atom.

5. The carbon catalyst according to claim 1, wherein the ratio of the nitrogen atom concentration (atomic %) to the carbon atom concentration (atomic %) obtained by X-ray photoelectron spectroscopy is 0.0005 or more.

6. The carbon catalyst according to claim 1, wherein a ratio of an area of ​​the quaternary type nitrogen atom peak to a total area of ​​the four nitrogen atom peaks obtained by peak separation of an N1s spectrum in a spectrum obtained by X-ray photoelectron spectroscopy into the following four nitrogen atom peaks: (1) a pyridine type nitrogen atom peak having a peak top in a range of 398.5±0.3 eV and a full width at half maximum of 1.4 eV; (2) a pyrrole / pyridone type nitrogen atom peak having a peak top in a range of 400.5±0.3 eV and a full width at half maximum of 1.4 eV; (3) a quaternary type nitrogen atom peak having a peak top in a range of 401.5±0.3 eV and a full width at half maximum of 1.4 eV; and (4) an oxidized type nitrogen atom peak having a peak top in a range of 402.5±0.3 eV and a full width at half maximum of 2.0 eV is 0.1% or more.

7. The BET specific surface area obtained by the nitrogen adsorption method is 50 m ２ The carbon catalyst according to claim 1 , wherein the carbon content is 1 / g or more.

8. An electrode comprising the carbon catalyst according to any one of claims 1 to 7.

9. A battery comprising the electrode according to claim 8.

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