Carbon catalysts, electrodes, and batteries

Abstract

Provided are carbon catalysts, electrodes, and batteries each having high catalytic activity and high durability. The carbon catalyst has an L / La ratio of 18 or more, the L / La ratio being the ratio of an average carbon mesh size L obtained by a temperature-programmed desorption analysis capable of raising a temperature to 1,600°C to a grain size La obtained from a diffraction peak in the vicinity of a diffraction angle (2θ) of 43° in an X-ray diffraction pattern obtained by powder X-ray diffractometry, and a ratio of a halogen atom concentration (atom %) obtained by X-ray photoelectron spectroscopy to a carbon atom concentration (atom %) is 0.0005 or more.

Description

Technical Field

[0001] This invention relates to carbon catalysts, electrodes, and batteries. Background Technology

[0002] Patent Document 1 describes a carbonaceous material having the following crystal structure, wherein: [The crystal structure is determined by wide-angle X-ray analysis]. <002> The spacing is 3.40 Å to 3.60 Å; the grain size along its c-axis is 15 Å to 150 Å; and the grain size along its a-axis is 25 Å to 75 Å. The carbonaceous material is characterized by a spectrum measured by laser Raman spectroscopy at an excitation wavelength of 532 nm, where the spacing is 1,360 cm⁻¹. -1 Near peak intensity (ID) at 1,580 cm⁻¹ -1 The intensity ratio (ID / IG) of the nearby peak intensity (IG) is 0.2 to 2.0; and the Ti content obtained by ICP atomic emission spectroscopy is 0.1 wt% to 30 wt%. Reference List Patent documents

[0003] [PTL 1] JP 2018-123447 A Invention Summary Technical issues

[0004] To date, it has been difficult to obtain carbon catalysts that simultaneously possess high catalytic activity and high durability.

[0005] The present invention was made in view of the above-mentioned problems, and one of the objects of the present invention is to provide carbon catalysts, electrodes and batteries that each have both high catalytic activity and high durability. Solution to the problem

[0006] [1] A carbon catalyst according to an embodiment of the present invention for solving the above-mentioned problems has an L / La ratio of 18 or greater, and has a ratio of halogen atom concentration (atomic %) to carbon atom concentration (atomic %) obtained by X-ray photoelectron spectroscopy of 0.0005 or greater, wherein the L / La ratio is the ratio of the average carbon network size L obtained by temperature-programmed desorption analysis capable of reaching 1,600 °C to the grain size La obtained by the diffraction peak near a diffraction angle (2θ) in the X-ray diffraction pattern obtained by powder X-ray diffraction using CuKα rays. According to the present invention, a carbon catalyst having both high catalytic activity and high durability is provided.

[0007] [2] In the carbon catalyst according to item [1] above, the average carbon network size L may be 5 nm or greater. [3] In the carbon catalyst according to item [1] or [2] above, the grain size La may be 10.00 nm or less.

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

[0009] [6] The percentage of the area of ​​the quaternary ammonium nitrogen atom peak of the carbon catalyst according to any one of the above items [1] to [5] relative to the total area of ​​the following four nitrogen atom peaks may be 0.1% or greater, which is obtained by peak separation of the N1s spectrum in the spectrum obtained by X-ray photoelectron spectroscopy into four nitrogen atom peaks: (1) pyridine nitrogen atom peak with a peak apex in the range of 398.5 ± 0.3 eV and a full width at half maximum (WHM) of 1.4 eV; (2) pyrrole / pyridone nitrogen atom peak with a peak apex in the range of 400.5 ± 0.3 eV and a full width at half maximum (WHM) of 1.4 eV; (3) quaternary ammonium nitrogen atom peak with a peak apex in the range of 401.5 ± 0.3 eV and a full width at half maximum (WHM) of 1.4 eV; and (4) oxidized nitrogen atom peak with a peak apex in the range of 402.5 ± 0.3 eV and a full width at half maximum (WHM) of 2.0 eV. [7] The carbon catalyst according to any one of the above items [1] to [6] can have a 50m obtained by nitrogen adsorption method. 2 / g or greater BET specific surface area.

[0010] [8] An electrode according to one embodiment of the present invention for solving the above problems comprises a carbon catalyst of any one of the above items [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-mentioned problems includes the electrodes of item [8] above. According to the present invention, a battery having both high catalytic activity and high durability is provided. Beneficial effects of the present invention

[0012] According to the present invention, carbon catalysts, electrodes, and batteries, each possessing both high catalytic activity and high durability, are provided. Attached Figure Description

[0013] Figure 1 This is an explanatory diagram of the halo-benzene model regarding the average carbon mesh size L. Figure 2 This is an explanatory diagram illustrating an example of the evaluation results of the properties of a carbon catalyst according to an embodiment of the present invention. Description of the implementation plan

[0014] One embodiment of the present invention will now be described. The present invention is not limited to the examples described in the embodiment.

[0015] The carbon catalyst according to one embodiment of the present invention (hereinafter referred to as "the catalyst of the present invention") is a carbon material exhibiting catalytic activity. The catalyst of the present invention primarily comprises carbon. Specifically, the carbon content of the catalyst of the present invention 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 of the present invention 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 of the present invention can be specified by freely combining any of the above lower limits and any of the above upper limits. The carbon content of the carbon catalyst is obtained by elemental analysis (combustion method).

[0016] The catalyst of the present invention exhibits catalytic activity on its own. That is, the catalyst of the present invention exhibits catalytic activity without the presence of any noble metal supported thereon. The catalytic activity to be exhibited by the catalyst of the present invention is, for example, reduction reaction catalytic activity and / or oxidation reaction catalytic activity, more specifically, oxygen reduction reaction catalytic activity and / or hydrogen oxidation reaction catalytic activity, and the catalyst of the present invention can at least exhibit oxygen reduction reaction catalytic activity.

[0017] The inventors of this invention have conducted in-depth research on techniques for obtaining carbon catalysts with both high catalytic activity and high durability, and have therefore uniquely discovered that carbon catalysts with a relatively large L / La ratio and including halogen atoms introduced therein, in addition to high catalytic activity, also exhibit high durability. The relatively large L / La ratio is the ratio of the average carbon network size L to the grain size La of the carbon structure of the carbon catalyst. Therefore, the inventors have completed this invention.

[0018] In other words, the catalyst of the present invention has an L / La ratio of 18 or greater, which is the ratio of the average carbon network size L obtained by temperature-programmed desorption analysis capable of heating to 1,600 °C to the grain size La obtained by the diffraction peak near the 43° diffraction angle (2θ) in the X-ray diffraction pattern obtained by powder X-ray diffraction using CuKα rays.

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

[0020] There is no particular upper limit to the L / La ratio of the catalyst of the present invention, as long as the effects of the present invention are obtained. However, the upper limit can 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 catalyst of the present invention can be specified by freely combining any of the above lower limit values ​​and any of the above upper limit values.

[0021] The L / La ratio contributes to improving the catalytic activity and durability of the catalyst of the present invention. In other words, for example, a carbon structure with a relatively large L / La ratio contributes to the effective improvement of the catalytic activity and durability of the catalyst of the present invention due to the increase in the curved portions of the carbon network surface that serves as the catalytic active site, and / or the reduction in the edge sites of the carbon network surface that serve as the catalytic active site, which can also serve as the starting point of degradation.

[0022] The average carbon network size L is obtained by temperature-programmed desorption analysis (hereinafter referred to as "high-temperature TPD") capable of reaching temperatures up to 1,600°C. In other words, in embodiments of the present invention, the total amount of carbon edge sites on the carbon catalyst is calculated using a temperature-programmed desorption analyzer capable of reaching temperatures up to 1,600°C (hereinafter referred to as "high-temperature TPD analyzer") based on the quantitative determination of desorbed gases during high-temperature TPD of the carbon catalyst, and the average carbon network size L determined from this amount is obtained using... Figure 1 The calculations were performed using the benzene model shown. Figure 1 In the equation shown, a0 represents the lattice constant of the graphite crystal along the a-axis, which is 0.2461 nm.

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

[0024] The average carbon network size L of the catalyst of the present invention can be, for example, 5,000 nm or less, 2,000 nm or less, 1,000 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 network size L of the catalyst of the present invention can be specified by freely combining any of the above lower limit values ​​and any of the above upper limit values.

[0025] The average carbon network size L contributes to improving the catalytic activity and durability of the catalyst of the present invention. In other words, for example, carbon structures with a relatively large average carbon network size L contribute to effective improvement in durability due to the reduction of edge sites on their carbon network, which can serve as the starting point of degradation.

[0026] The grain size La was obtained from the diffraction peak near the 43° diffraction angle (2θ) in the X-ray diffraction pattern of the carbon catalyst obtained by powder X-ray diffraction using CuKα rays. In this paper, when the carbon catalyst has the following structure, i.e., in the grains forming curved carbon network surfaces that contribute to its catalytic activity, the carbon hexagonal network surfaces are connected and extended along their a-axis direction, then the diffraction peak f appears in the X-ray diffraction pattern of the carbon catalyst using CuKα rays. 10 The diffraction peak f 10 It is a carbon (10) diffraction line, with its peak apex near a diffraction angle (2θ) of 43° (e.g., in the range above 35° to below 60°). Diffraction peak f 10 A diffraction peak is defined, for example, as having a diffraction angle (2θ) of 43.5° ± 1.0° and a full width at half maximum (FWHM) of 7.5° ± 6.5°.

[0027] When the carbon catalyst contains iron, diffraction peaks originating from iron may also appear near a diffraction angle of 43° (2θ). That is, in this case, the diffraction peak f, which is a diffraction line originating from iron, Fe The above diffraction peaks f in the diffraction lines of carbon structures derived from carbon catalysts 10 Mixing. In view of the foregoing, for iron-containing carbon catalysts, the diffraction peak near a diffraction angle of 43° (2θ) is separated into two diffraction peaks by this peak separation in the X-ray diffraction pattern performed in the examples described later, namely f 10 peak and f Fe peak.

[0028] By analyzing the diffraction peak f 10 Calculate the grain size La. That is, by analyzing the diffraction peaks f. 10Substituting the Bragg angle and half-width at half-maximum (WHM) into the following Scherrer equation, we can calculate the grain size La (nm): La = Kλ / (βcosθ). In the Scherrer equation, K represents the Scherrer constant (0.94), λ represents the wavelength of CuKα rays (0.15418 nm), β represents the full width at half-maximum (WHM) in radians, and θ represents the Bragg angle in radians.

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

[0030] The crystallite size La of the catalyst of the present invention can be, for example, 0.50 nm or greater, 0.70 nm or greater, 1.00 nm or greater, 1.10 nm or greater, 1.20 nm or greater, 1.30 nm or greater, 1.40 nm or greater, 1.50 nm or greater, or 1.60 nm or greater. The crystallite size La of the catalyst of the present invention can be specified by freely combining any of the above lower limit values ​​and any of the above upper limit values.

[0031] The grain size La contributes to improving the catalytic activity of the catalyst of the present invention. That is, for example, a carbon structure with a relatively large average carbon network surface size L and a relatively small grain size La contributes to the effective improvement of catalytic activity due to the increase in the curved portions of the carbon network surface that serve as catalytic active sites.

[0032] The grain size Lc was obtained from the diffraction peaks near the 26° diffraction angle (2θ) in the X-ray diffraction pattern of the carbon catalyst obtained by powder X-ray diffraction using CuKα rays. Specifically, the grain size Lc was determined by the diffraction peak f. 002 Obtain the diffraction peak f 002 The (002) diffraction line of carbon with a peak near a diffraction angle 2θ of 26° (e.g., in the range above 24.0° to below 26.5°) is shown in the X-ray diffraction pattern obtained by powder X-ray diffraction using CuKα rays. The diffraction peak f 002 A diffraction peak is defined as, for example, a diffraction angle (2θ) of 25.0° or greater and 26.5° or less, and a full width at half maximum (FWHM) of 0.05° or greater and 20° or less.

[0033] By analyzing the diffraction peak f002 Calculate the grain size Lc. In other words, by analyzing the diffraction peaks f... 002 Substituting the Bragg angle and full width at half maximum (FWHM) into the following Scherrer equation, we can calculate the grain size Lc (nm): Lc = Kλ / (βcosθ). In the Scherrer equation, K represents the Scherrer constant (0.94), λ represents the wavelength of CuKα rays (0.15418 nm), β represents the full width at half maximum (in radians), and θ represents the Bragg angle (in radians).

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

[0035] The crystallite size Lc of the catalyst of the present invention can be, for example, 0.50 nm or greater, 0.70 nm or greater, 0.80 nm or greater, 0.90 nm or greater, 1.00 nm or greater, or 1.10 nm or greater. The crystallite size Lc of the catalyst of the present invention can be specified by freely combining any of the above lower limit values ​​and any of the above upper limit values.

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

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

[0038] There is no particular upper limit to the halogen / C ratio of the catalyst of the present invention, as long as the effects of the present invention are obtained. However, the upper limit 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 catalyst of the present invention can be specified by freely combining any of the above lower limit values ​​and any of the above upper limit values.

[0039] The halogen atoms in the catalyst of this invention are not particularly limited, as long as the effects of this invention are achieved. However, the halogen atoms are preferably selected from one or more of the following: fluorine atoms; chlorine atoms; bromine atoms; and iodine atoms. In the embodiments described later, chlorine atoms are used as halogen atoms. However, regardless of whether they are chlorine atoms, halogen atoms share the following common characteristics: each atom has seven valence electrons in its outermost shell and forms single bonds with carbon atoms at the edge sites of the carbon network in the carbon structure of the carbon catalyst to form a closed shell structure.

[0040] The halogen / C ratio of the catalyst of the present invention is calculated by dividing the halogen atom concentration (atomic%) of the catalyst of the present invention obtained by XPS by its carbon atom concentration (atomic%). In this respect, when the catalyst of the present invention contains two or more halogen atoms, the halogen atom concentration (atomic%) of the catalyst of the present invention is the total concentration (atomic%) of said two or more halogen atoms obtained by XPS.

[0041] The halogen / C ratio contributes to improving the catalytic activity and durability of the catalyst of the present invention. That is, for example, increasing the halogen / C ratio in the carbon structure contributes to the effective improvement of its durability, due to the increase in edge sites bonded to halogen atoms at the edge sites of the carbon network in the carbon structure.

[0042] In this paper, the amount of halogen atoms introduced into the carbon structure is related to the amount of edge sites in the carbon structure. That is, in the case of a carbon structure, for example, with a relatively large average carbon network size L, the number of edge sites in the carbon network is small. Therefore, the halogen / C ratio of the carbon catalyst is not very large.

[0043] There is no particular limitation on the concentration of halogen atoms obtained by the catalyst of the present invention through its XPS, as long as the effect of the present invention is obtained. However, the concentration may be, for example, 0.10 (atomic %) or greater, and preferably 0.20 (atomic %) or greater, more preferably 0.30 (atomic %) or greater, even more preferably 0.40 (atomic %) or greater, even more preferably 0.50 (atomic %) or greater, even more preferably 0.60 (atomic %) or greater, even more preferably 0.70 (atomic %) or greater, even more preferably 0.80 (atomic %) or greater, even more preferably 0.90 (atomic %) or greater, even more preferably 1.00 (atomic %) or greater, even more preferably 1.05 (v) or greater, even more preferably 1.10 (atomic %) or greater, even more preferably 1.15 (atomic %) or greater, even more preferably 1.20 (atomic %) or greater, even more preferably 1.25 (atomic %) or greater, and particularly preferably 1.30 (atomic %) or greater.

[0044] The halogen atom concentration of the catalyst of the present invention obtained by XPS can 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 of the present invention obtained by XPS can be specified by freely combining any of the above lower limit values ​​and any of the above upper limit values.

[0045] The halogen atom concentration obtained by XPS contributes to improving the durability of the catalyst of the present invention. That is, for example, an increase in the halogen atom concentration in the carbon structure of a carbon catalyst contributes to an effective improvement in its durability due to the increase in edge sites bonded to halogen atoms at the edge sites of the carbon network in the carbon structure.

[0046] As mentioned above, the amount of halogen atoms introduced into the carbon structure is related to the amount of edge sites in the carbon structure. Therefore, in the case of a carbon structure, for example, with a relatively large average carbon network size L, the number of edge sites in the carbon network is small. Consequently, the halogen atom concentration in the carbon catalyst does not become very high.

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

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

[0049] The N / C ratio of the catalyst of the present invention can 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 catalyst of the present invention can be specified by freely combining any of the above lower limit values ​​and any of the above upper limit values.

[0050] The N / C ratio contributes to improving the catalytic activity and durability of the catalyst of the present invention. That is, for example, increasing the N / C ratio in the carbon structure of a carbon catalyst contributes to the effective improvement of its catalytic activity due to the increase in catalytic active sites derived from nitrogen atoms in the carbon structure.

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

[0052] The nitrogen atom concentration obtained by XPS of the catalyst of the present invention can 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 obtained by XPS of the catalyst of the present invention can be specified by freely combining any of the above lower limit values ​​and any of the above upper limit values.

[0053] The nitrogen atom concentration obtained through XPS helps to improve the catalytic activity and durability of the catalyst of the present invention. That is, for example, an increase in the nitrogen atom concentration in the carbon structure of a carbon catalyst contributes to an effective improvement in its catalytic activity due to the increase in catalytic active sites derived from nitrogen atoms in the carbon structure.

[0054] The area of ​​the quaternary ammonium nitrogen atom peak of the catalyst of the present invention is 0.1% or greater relative to the total area of ​​the following four nitrogen atom peaks (i.e., the sum of the areas of the pyridine nitrogen atom peak, the pyrrole / pyridone nitrogen atom peak, the quaternary ammonium nitrogen atom peak and the oxidized nitrogen atom peak). The percentage of quaternary ammonium nitrogen was obtained by peak separation of the N1s spectrum obtained by XPS into the following four nitrogen atom peaks: (1) a pyridine nitrogen atom peak with a peak apex in the range of 398.5 ± 0.3 eV and a full width at half maximum (WHM) of 1.4 eV (the peak originating from pyridine nitrogen atoms); (2) a pyrrole / pyridone nitrogen atom peak with a peak apex in the range of 400.5 ± 0.3 eV and a full width at half maximum (WHM) of 1.4 eV (the peak originating from pyrrole nitrogen atoms and pyridone nitrogen atoms); (3) a quaternary ammonium nitrogen atom peak with a peak apex in the range of 401.5 ± 0.3 eV and a full width at half maximum (WHM) of 1.4 eV (the peak originating from quaternary ammonium nitrogen atoms); and (4) an oxidized nitrogen atom peak with a peak apex in the range of 402.5 ± 0.3 eV and a full width at half maximum (WHM) of 2.0 eV (the peak originating from oxidized nitrogen atoms).

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

[0056] The percentage of quaternary ammonium nitrogen in the catalyst of the present invention can 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 percentage of quaternary ammonium nitrogen in the catalyst of the present invention can be specified by freely combining any of the above lower limits and any of the above upper limits.

[0057] In this paper, pyridine nitrogen atoms, pyrrole / pyridone nitrogen atoms, and oxidized nitrogen atoms are mainly located at the edge sites of the carbon network in the carbon structure of the carbon catalyst, while quaternary ammonium nitrogen atoms are located inside the carbon network.

[0058] The percentage of quaternary ammonium nitrogen contributes to improving the catalytic activity and durability of the catalyst of the present invention. That is, for example, increasing the percentage of quaternary ammonium nitrogen in the carbon structure contributes to the effective improvement of catalytic activity because the quaternary ammonium nitrogen atoms doped into the carbon network facets of the carbon structure lead to an increase in the electron density of the curved portions of the carbon network facets.

[0059] The percentage of the area of ​​the pyridine nitrogen atom peak of the catalyst of the present invention relative to the total area of ​​the four nitrogen atom peaks (1) to (4) (hereinafter referred to as "pyridine nitrogen percentage") can be 50.0% or less, which is obtained by performing peak separation of the N1s spectrum obtained by XPS into four nitrogen atom peaks.

[0060] In this case, the percentage of pyridine nitrogen in the catalyst of the present invention is 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 percentage of pyridine nitrogen in the catalyst of the present invention can be, for example, 1.0% or greater, 3.0% or greater, 5.0% or greater, 7.0% or greater, 9.0% or greater, or 10.0% or greater. The percentage of pyridine nitrogen in the catalyst of the present invention can be specified by freely combining any of the above lower limits and any of the above upper limits.

[0062] The catalyst of the present invention may have 70.0% or less of the area of ​​the pyrrole / pyridone type nitrogen atom peak relative to the total area of ​​the four nitrogen atom peaks (1) to (4) (hereinafter referred to as "pyrrole / pyridone type nitrogen percentage"), which is obtained by peak separation of the N1s spectrum obtained by XPS into four nitrogen atom peaks.

[0063] In this case, the pyrrole / pyridone nitrogen percentage of the catalyst of the present invention 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 nitrogen percentage of the catalyst of the present invention can 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 nitrogen percentage of the catalyst of the present invention can be specified by freely combining any of the above lower limits and any of the above upper limits.

[0065] The percentage of the area of ​​the oxidized nitrogen atom peak of the catalyst of the present invention relative to the total area of ​​the four nitrogen atom peaks (1) to (4) (hereinafter referred to as "oxidized nitrogen percentage") can be 1.0% or greater. The oxidized nitrogen percentage is obtained by performing peak separation of the N1s spectrum in the spectrum obtained by XPS into four nitrogen atom peaks.

[0066] In this case, the percentage of oxidized nitrogen in the catalyst of the present invention is 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 percentage of oxidized nitrogen in the catalyst of the present invention 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 percentage of oxidized nitrogen in the catalyst of the present invention may be specified by freely combining any of the above lower limits and any of the above upper limits.

[0068] The concentration of carbon atoms obtained by the catalyst of the present invention through its XPS is not particularly limited, as long as the effects of the present invention are achieved. However, the concentration may be, for example, 50.0 (atomic %) or more, preferably 60.0 (atomic %) or more, more preferably 70.0 (atomic %) or more, 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 catalyst of the present invention obtained by XPS can 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 catalyst of the present invention obtained by XPS can be specified by freely combining any of the above lower limit values ​​and any of the above upper limit values.

[0070] The catalyst of the present invention may contain oxygen atoms. In this case, the oxygen atom concentration obtained by the catalyst of the present invention through its 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 atom concentration of the catalyst of the present invention obtained by XPS can 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 atom concentration of the catalyst of the present invention obtained by XPS can be specified by freely combining any of the above lower limit values ​​and any of the above upper limit values.

[0072] The BET specific surface area of ​​the catalyst of the present invention obtained by nitrogen adsorption is not particularly limited, as long as the effects of the present invention are obtained. However, a BET specific surface area of, for example, 50 m² is preferred. 2 / g or greater, more preferably 100m 2 / g or greater, more preferably 200m 2 / g or greater, and more preferably 300m 2 / g or greater, more preferably 400m 2 / g or greater, more preferably 450m 2 / g or greater, more preferably 500m 2 / g or greater, particularly preferably 550m 2 / g or larger.

[0073] The BET specific surface area of ​​the catalyst of the present invention can be, for example, 4,000 m². 2 / g or less, 3,000m 2 / g or less, 3,500m 2 / g or less, 2,000m 2 / g or less, 1,500m 2 / g or less, 1,000m 2 / g or less, 900m 2 / g or less, or 800m 2 / g or less. The BET specific surface area of ​​the catalyst of the present invention can be specified by freely combining any of the above lower limit values ​​and any of the above upper limit values.

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

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

[0076] There are no particular limitations on the non-precious metals in the catalyst of this invention, as long as the effects of this invention are achieved. However, the non-precious metal can be, for example, any non-precious metal belonging to any one of Groups 2 to 14 of the periodic table, and preferably any non-precious metal belonging to any one of the third to fifth periods of Groups 2 to 14 of the periodic table, and more preferably any non-precious metal belonging to any one of the third and fourth periods of Groups 2 to 14 of the periodic table.

[0077] Specifically, the non-precious metal in the catalyst of the present invention is more preferably selected from one or more of the following: 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 selected from one or more of the following: Cu, Zn, and Sn.

[0078] The catalyst of the present invention may contain non-precious metals from the raw materials used for carbonization in its production. That is, as described below, the method for producing the catalyst of the present invention may include carbonizing a raw material containing non-precious metals. In this case, the catalyst of the present invention contains non-precious metals because the raw material used for carbonization initially contained non-precious metals.

[0079] Specifically, the catalyst of the present invention contains non-precious metals within the framework that forms the porous structure of the catalyst. That is, even when the catalyst of the present invention is a carbonized material produced by a carbonization followed by metal removal process as described later, the non-precious metals from the raw materials used for carbonization remain within the framework of the catalyst of the present invention. In this respect, the weight of the non-precious metals within the framework of the catalyst of the present invention can be greater than the weight of the non-precious metals on the surface of the framework of the catalyst of the present invention.

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

[0081] The content of non-precious metals in the catalyst of the present invention (or the total content of multiple non-precious metals when the catalyst of the present invention contains multiple non-precious metals) is not particularly limited, as long as the effects of the present invention are obtained. However, the content may be, for example, 50 ppm or more, 100 ppm or more, 500 ppm or more, 1,000 ppm or more, 5,000 ppm or more, 10,000 ppm or more, 50,000 ppm or more, or 100,000 ppm or more.

[0082] The content of non-precious metals in the catalyst of the present invention can 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 content of non-precious metals in the catalyst of the present invention can be specified by freely combining any of the above lower limits and any of the above upper limits. 1 ppm represents 0.0001% by weight. The content of non-precious metals is obtained by inductively coupled plasma (ICP) atomic emission spectrometry.

[0083] The concentration of non-precious metal atoms obtained by XPS of the catalyst of the present invention (which is the sum of the atomic concentrations of the multiple non-precious metals when the catalyst of the present invention contains multiple non-precious metals) can be, for example, 0.001 (atomic %) or greater, 0.005 (atomic %) or greater, or 0.010 (atomic %) or greater.

[0084] The non-precious metal atomic concentration of the catalyst of the present invention obtained by XPS can 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-precious metal atomic concentration of the catalyst of the present invention obtained by XPS can be specified by freely combining any of the above lower limits and any of the above upper limits.

[0085] The non-precious metals in the catalyst of the present invention contribute to improving the catalytic activity of the catalyst in its production method. That is, for example, when the catalyst of the present invention contains non-precious metals from the feedstock used for carbonization, a specific carbon structure including catalytically active sites can be effectively formed by carbonization in the presence of non-precious metals.

[0086] However, the catalytic activity of the catalyst of the present invention can be primarily based on the catalytically active sites in its carbon structure, rather than on the non-precious metals derived from its feedstock. This is supported by the fact that even when the catalyst of the present invention, containing non-precious metals from the feedstock used for carbonization, undergoes a metal removal treatment to reduce the non-precious metal content, the catalytic activity of the catalyst of the present invention is not significantly reduced after the metal removal treatment compared to 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 catalyst of the present invention, the content of metals other than Fe, Cu, Zn, and Sn, or the content of metals other than Cu, Zn, and Sn can 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 content of non-precious metals is obtained by inductively coupled plasma (ICP) atomic emission spectrometry.

[0088] The catalyst of the present invention may be free of any precious metals. That is, as described above, the catalyst of the present invention exhibits catalytic activity even without the presence of precious metals supported thereon, therefore it is not required that the catalyst include precious metals. However, the catalyst of the present invention can be used as a carbon support for supporting metal catalysts such as precious metals.

[0089] There are no particular limitations on the method for preparing the catalyst of the present invention, as long as the catalyst of the present invention having the above-described characteristics is obtained by the method. However, the method is preferably a method including, for example, the following steps: carbonizing a raw material containing organic matter; and subjecting the carbonized material obtained by carbonization to halogen introduction treatment.

[0090] There are no particular restrictions on the organic matter in the raw materials, as long as the organic matter can be carbonized. The organic compounds in the organic matter can be polymers (e.g., thermosetting resins and / or thermoplastic resins), and / or can be organic compounds with a small molecular weight.

[0091] The organic material is preferably a nitrogen-containing organic material. Nitrogen-containing organic materials include, for example, nitrogen-containing organic compounds. There are no particular limitations on the nitrogen-containing organic compounds, as long as the organic compound contains nitrogen atoms in its molecule. There are no particular limitations on the nitrogen atom content in the nitrogen-containing organic compound, as long as the effects of the present invention are obtained. For example, nitrogen-containing organic compounds in which the nitrogen atom content falls within the range suitable for obtaining the catalyst of the present invention having the above-described properties can be appropriately selected and used.

[0092] Specific examples of organic substances may include one or more selected from the group consisting of: quinoxaline (e.g., 2-hydroxyquinoxaline); phenanthroline (e.g., 1,10-phenanthroline); alginate (e.g., ammonium alginate); polyacrylonitrile; polyacrylonitrile-polyacrylic acid copolymer; polyacrylonitrile-polymethyl acrylate copolymer; polyacrylonitrile-polymethacrylic acid copolymer; polyacrylonitrile-polymethyl methacrylate copolymer; polyacrylonitrile-polymethyl methacrylate copolymer; phenolic resin; polyfurfuryl alcohol; furan; furan resin; phenol-formaldehyde resin; melamine; melamine resin; epoxy resin; nitrogen-containing chelating resin (e.g., one or more substances selected from: polyamine resin; iminodiacetic acid resin; aminophosphate resin; and aminomethylphosphonic acid resin); polyamide-imide resin; pyrrole; polypyrrole; polyvinylpyrrole; 3-methylpolypyrrole; acrylonitrile; polyvinylidene chloride; thiazolinone Fern; Oxazole; Thiazole; Pyrazole; Vinylpyridine; Polyvinylpyridine; Pyridazine; Pyrimidine; Piperazine; Pyran; Morpholine; Imidazole; 1-Methylimidazole; 2-Methylimidazole; Aniline; Polyaniline; Succinate dihydrazide; Adipic acid dihydrazide; Polysulfone; Polyaminobismaleimide; Polyimide; Polyvinyl alcohol; Polyvinyl butyral; Benzimidazole; Polybenzimidazole; Polyamide; Polyester; Polylactic acid; Polyether; Polyetheretherketone; Cellulose; Carboxymethyl cellulose; Lignin; Butylene; chitosan; pitch; silk; wool; polyamino acids; nucleic acids; DNA; RNA; hydrazine; acylhydrazine; urea; salen; polycarbazole; polybismaleimide; triazine; polyacrylic acid; polyacrylate; polymethacrylate; polymethacrylate; polymethacrylic acid; polyurethane; polyamide amine; polycarbodiimide; naphthalene; naphthalene analogs; anthracene; anthracene analogs; hydroxybenzene; hydroxybenzene analogs; carbazole; quinoline; cyanuric acid; naphthoic acid; methylene blue; and phthalocyanine.

[0093] Carbonization is performed by heating the raw material at a temperature at which the organic matter in the raw material is carbonized. There are no particular limitations on the carbonization temperature, as long as the raw material is carbonized at that temperature. The carbonization temperature can 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 can be, for example, 3,000°C or lower, preferably 2,500°C or lower, more preferably 2,000°C or lower, even more preferably 1,500°C or lower, and particularly preferably 1,200°C or lower. The carbonization temperature can be specified by freely combining any of the above lower and upper limits. There is no particular limitation on the heating rate to the carbonization temperature, and it can 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 nitrogen.

[0095] Halogen introduction treatment is a process used to introduce halogen atoms into the carbon structure of a carbide material obtained by carbonization. Specifically, halogen introduction treatment is performed, for example, by contacting the carbide 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 halogen introduction treatment is achieved. However, this content is preferably, for example, 1% by volume or more, more preferably 5% by volume or more, and particularly preferably 10% by volume or more. The gas mixed with the halogen gas in the halogen-containing gas is not particularly limited, as long as the effect of halogen introduction treatment is achieved. However, the gas is preferably an inert gas (e.g., argon and / or nitrogen). The heating temperature in the halogen introduction treatment is not particularly limited, as long as the effect of halogen introduction treatment is achieved. However, the temperature is preferably, for example, 100°C or higher, more preferably 300°C or higher, more preferably 500°C or higher, and particularly preferably 600°C or higher.

[0096] The preferred method for producing the catalyst of the present invention includes, for example, the following steps: carbonizing a raw material containing organic matter and non-precious metals; and subjecting the carbonized material obtained by carbonization to a halogen introduction treatment. In this case, the method for producing the catalyst of the present invention may include the following steps: carbonizing a raw material containing organic matter and non-precious metals; subjecting the carbonized material obtained by carbonization to a metal removal treatment; and subjecting the carbonized material to a halogen introduction treatment after the metal removal treatment. The metal removal treatment is a treatment used to reduce the amount of non-precious metals derived from the raw material in the carbonized material. Specifically, the metal removal treatment is preferably, for example, acid washing and / or electrolytic treatment.

[0097] An electrode according to an embodiment of the present invention (hereinafter referred to as "the electrode of the present invention") comprises the catalyst of the present invention. That is, the electrode of the present invention may comprise an electrode substrate and the catalyst of the present invention supported on the electrode substrate. The electrode of the present invention is preferably a battery electrode. Specifically, the electrode of the present invention is preferably an electrode for, for example, fuel cells (e.g., polymer electrolyte fuel cells or microbial fuel cells), air batteries, water electrolyzers (e.g., polymer electrolyte water electrolyzers), redox flow batteries, or halogen batteries.

[0098] The electrode of the present invention can be a cathode or an anode, but is preferably a cathode. That is, the electrode of the present invention is the cathode or anode of a fuel cell, an air battery, a water electrolyzer, a redox flow cell, or a halogen battery, preferably a cathode.

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

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

[0101] Next, specific embodiments according to the present invention will be described. Example

[0102] [Example 1] 1.0 g of 2-hydroxyquinoxaline was dissolved in 20 mL of acetone, and then 25.95 g of tin(II) chloride (SnCl2) was added. The mixture was then mixed in a mortar until homogeneous. Thus, the raw material for carbonization was obtained.

[0103] Then, carbonization is carried out. That is, the obtained raw material is loaded into the HB tube and its temperature is raised to 650°C in a Siliconit furnace under a nitrogen atmosphere at a rate of 50°C / min, and then the raw material is held at 650°C for 30 minutes to carbonize.

[0104] Subsequently, the carbonized material obtained through carbonization is subjected to a pulverization process. Specifically, silicon nitride balls with a diameter of 10 mm are placed in a planetary ball mill (P-7, manufactured by Fritsch Japan Co., Ltd.), and the carbonized material is pulverized using the planetary ball mill.

[0105] In addition, the carbide material undergoes a metal removal treatment. Specifically, 100 mL of concentrated hydrochloric acid is added to the pulverized carbide material, and the mixture is heated to 80°C and stirred for 2 hours. Afterward, the solution containing the carbide material is filtered through a filter membrane, and the carbide material is washed with distilled water until the filtrate becomes neutral. The collected carbide material is then dried under vacuum.

[0106] Next, the carbide material is heat-treated. Specifically, the carbide material, which has undergone metal removal, is loaded into a quartz tube and heated in an imaging furnace under a nitrogen atmosphere, held at 1,000°C for 30 minutes for heat treatment. This yields a carbon catalyst.

[0107] In addition, the carbon catalyst was subjected to halogen introduction treatment. That is, the carbon catalyst obtained as described above was loaded into a quartz tube and heated to 600°C in an imaging furnace in a chlorine atmosphere (a mixture of 10 vol% chlorine and 90 vol% argon) at a heating rate of 50°C / min, and then the carbon catalyst was held at 600°C for 30 minutes.

[0108] The chlorine atmosphere was then switched to an argon atmosphere (100% by volume), while the temperature was maintained at 600°C. The carbon catalyst was then held in the argon atmosphere at 600°C for 10 minutes. Thus, the carbon catalyst of Example 1 was obtained.

[0109] [Example 2] The carbon catalyst was obtained in the same manner as in Example 1 above, except that 1.0 g of 1,10-phenanthroline was used instead of 2-hydroxyquinoxaline for the raw materials used for carbonization, and the amount of tin(II) chloride (SnCl2) added was changed to 21.04 g.

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

[0111] [Example 3] The carbon catalyst was obtained in the same manner as in Example 1 above, except that 5.0 g of ammonium alginate was used instead of 2-hydroxyquinoxaline for the raw materials used for carbonization, and the amount of tin(II) chloride (SnCl2) added was changed to 4.91 g.

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

[0113] [Example 4] The carbon catalyst was obtained in the same manner as in Example 3 above, except that 3.53 g of zinc(II) chloride (ZnCl2) was used instead of tin(II) chloride (SnCl2) for the raw materials used for carbonization.

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

[0115] [Example C1] 0.5 g of polyacrylonitrile was dissolved in 200 mL of dimethylformamide, and 25.34 g of (II) copper chloride (CuCl2) was further added to prepare a homogeneous solution. The solution was dried under vacuum at 80 °C for 1 day to provide raw materials for carbonization.

[0116] Then, carbonization is carried out. That is, the obtained raw material is loaded into the HB tube and its temperature is raised to 800°C in the Siliconit furnace at a rate of 50°C / min under a nitrogen atmosphere, and then the raw material is held at 800°C for 30 minutes to carry out carbonization.

[0117] Subsequently, the carbonized material obtained through carbonization is subjected to a pulverization process. Specifically, silicon nitride balls with a diameter of 10 mm are placed in a planetary ball mill (P-7, manufactured by Fritsch Japan Co., Ltd.), and the carbonized material is pulverized using the planetary ball mill.

[0118] In addition, the carbide material undergoes a metal removal treatment. Specifically, 100 mL of concentrated nitric acid is added to the pulverized carbide material, and the mixture is heated to 80°C and stirred for 2 hours. Afterward, the solution containing the carbide material is filtered through a filter membrane, and the carbide material is washed with distilled water until the filtrate becomes neutral. The collected carbide material is then dried under vacuum.

[0119] Next, the carbide material is heat-treated. Specifically, the carbide material, which has undergone metal removal, is loaded into a quartz tube, heated in an imaging furnace under a nitrogen atmosphere, and held at 800°C for 30 minutes for heat treatment. Thus, a carbon catalyst is obtained.

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

[0121] [Example C2] 3.0 g of phthalocyanine was dispersed in 30 mL of acetone, and then 15.68 g of copper(II) chloride (CuCl2) and 0.145 g of ferric chloride (III) hexahydrate (FeCl3∙6H2O) were added. The mixture was then mortared and mixed until homogeneous. Thus, the raw material for carbonization was obtained.

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

[0123] In addition, the carbide material undergoes a metal removal treatment. Specifically, 100 mL of concentrated nitric acid is added to the pulverized carbide material, and the mixture is heated to 80°C and stirred for 2 hours. Afterward, the solution containing the carbide material is filtered through a filter membrane, and the carbide material is washed with distilled water until the filtrate becomes neutral. The collected carbide material is then dried under vacuum.

[0124] Next, the carbide material is heat-treated. Specifically, the carbide material, which has undergone metal removal, is loaded into a quartz tube, heated in an imaging furnace under a nitrogen atmosphere, and held at 600°C for 30 minutes for heat treatment. Thus, a carbon catalyst is obtained.

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

[0126] [Example C3] 2.0 g of phthalocyanine was dispersed in 20 mL of acetone, and then 14.74 g of tin(II) chloride (SnCl2) was added. The mixture was then mortared and mixed until homogeneous. Thus, the raw material for carbonization was obtained.

[0127] Then, the carbonization of the raw materials, the crushing of the carbonized material obtained by carbonization, and the metal removal treatment of the carbonized material after crushing are carried out in the same manner as in Example 1 above.

[0128] Next, the carbide material is heat-treated. Specifically, the carbide material, which has undergone metal removal, is loaded into a quartz tube, heated in an imaging furnace under a nitrogen atmosphere, and held at 600°C for 30 minutes for heat treatment. Thus, a carbon catalyst is obtained.

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

[0130] Powder X-ray Diffraction Powder X-ray diffraction (XRD) measurements of the carbon catalyst were performed using an X-ray diffractometer (XRD-6100, manufactured by Rigaku Corporation). Cuk α rays were used as the incident X-rays, and the voltage and current applied to the X-ray tube were set to 40 kV and 15 mA, respectively. The measurement angle range (2θ) was set from 5° to 90°. The grain sizes Lc and La were obtained by analyzing the powder X-ray diffraction patterns obtained from the XRD measurements of the carbon catalyst, as described below.

[0131] That is, when the carbon catalyst has a laminated structure extending along its c-axis in the grains forming the carbon network, a diffraction peak f appears in the X-ray diffraction pattern of the carbon catalyst when CuKα rays are used. 002 This is a (002) diffraction line where carbon has a peak near a diffraction angle (2θ) of 26° (e.g., in the range of 24.0° or greater to 26.5° or less). In this embodiment, the diffraction peak f 002 A diffraction peak is defined as having a diffraction angle (2θ) greater than or equal to 25.0° and less than or equal to 26.5° and a full width at half maximum (FWHM) greater than or equal to 0.05° and less than or equal to 20°.

[0132] Then, by analyzing f 002 Calculate the grain size Lc. That is, first, perform X-ray diffraction analysis on the obtained X-ray diffraction pattern with respect to the Lorentz factor (L), polarization factor (P), absorption factor (A), and atomic scattering factor of carbon (f). c Intensity correction is performed first, followed by background correction. Specifically, intensity correction is performed by dividing the diffraction intensity at each measurement angle by a correction factor calculated from the following equation: Correction factor = L * P * A * f c 2 There are no particular limitations on the method used for background correction, as long as the baselines can be aligned with each other. However, in this embodiment, background correction is performed by determining an approximate straight line (linear function) from the interval data from the peak start point to the peak end point; and subtracting the value of this approximate straight line from each diffraction intensity.

[0133] Next, by adjusting the diffraction peak f in the obtained corrected X-ray diffraction pattern... 002 Substituting the Bragg angle and full width at half maximum (FWHM) into the following Scherrer equation, we can calculate the grain size Lc: Lc = Kλ / (βcosθ). In the Scherrer equation, K represents the Scherrer constant (0.94), λ represents the wavelength of CuKα rays (0.15418 nm), β represents the full width at half maximum (in radians), and θ represents the Bragg angle (in radians).

[0134] When the carbon catalyst has a stacked structure in the grains forming the carbon network, with the carbon hexagonal network extending along its a-axis, a diffraction peak f appears in the X-ray diffraction pattern of the carbon catalyst using CuKα rays. 10 diffraction peak f 10 It is a (10) diffraction line with a peak near a diffraction angle of 43° (2θ) (e.g., in the range of 35° or greater to 60° or less).

[0135] In this paper, when the carbon catalyst contains iron, diffraction peaks originating from iron can also appear near a diffraction angle of 43° (2θ). That is, in this case, the diffraction peak f, as a diffraction line originating from iron, is...Fe The (10) diffraction lines of the aforementioned carbon are mixed in the diffraction lines derived from the carbon structure of the carbon catalyst. In view of the foregoing, for iron-containing carbon catalysts, the diffraction peak near the 43° diffraction angle (2θ) is separated into two diffraction peaks by peak separation in the X-ray diffraction pattern, namely peak f. 10 Hefeng f Fe .

[0136] Peak separation is performed by approximating overlapping diffraction peaks by superimposing them onto the Voigt fundamental waveform. The background-corrected X-ray diffraction pattern is optimized and fitted using peak intensity, peak full width at half maximum (FWHM), and peak position as parameters for the Voigt function used for each component. The method used for background correction is not particularly limited, as long as the baselines can be aligned with each other. However, in this embodiment, background correction is performed by determining an approximate straight line (linear function) from the interval data from the peak initiation point to the peak termination point; and subtracting the value of this approximate straight line from each diffraction intensity.

[0137] More specifically, peak separation is performed through the following procedure. In the X-ray diffraction pattern obtained using CuKα rays after background correction as described above, the diffraction peak with a apex near the 43° diffraction angle 2θ is approximated by superimposing it onto the Voigt basic waveform, optimizing its peak intensity, full width at half maximum (FWHM), and peak position. Furthermore, curve fitting is performed on each of the two overlapping diffraction peaks.

[0138] Curve fitting was performed to minimize the sum of squared residuals. In this paper, the term "squared residual" refers to the square of the residual at each measured diffraction angle, and the term "sum of squared residuals" refers to the sum of these squared residuals. The term "residual" refers to the intensity of the diffraction peak with a apex near a diffraction angle of 43° 2θ in an X-ray diffraction pattern using CuKα rays, compared to the intensity of the two diffraction peaks obtained by separation. 10 and f Fe The difference between the sum of their intensities.

[0139] Regarding iron-containing carbon catalysts, two diffraction peaks were obtained through this peak separation method. 10 and f Fe Specifically, the diffraction peak f 10 The diffraction peak is defined as having a diffraction angle (2θ) of 43.5° ± 1.0° and a full width at half maximum (FWHM) of 7.5° ± 6.5°. The diffraction peak f... Fe A diffraction peak is defined as having a diffraction angle (2θ) of 44.0°±1.0° and a full width at half maximum (FWHM) of 0.5°±0.3°.

[0140] Regarding iron-free carbon catalysts, diffraction peak f10 It is defined as a diffraction peak with a diffraction angle (2θ) of 43.5°±1.0° and a full width at half maximum (WHM) of 7.5°±6.5° in the X-ray diffraction pattern of CuKα rays used in carbon catalysts.

[0141] Then, by analyzing the obtained diffraction peak f 10 To calculate the grain size La. That is, by analyzing the diffraction peaks f 10 Substituting the Bragg angle and half-width at half-maximum (WHM) into the following Scherrer equation, we can calculate the grain size La: La = Kλ / (βcosθ). In the Scherrer equation, K represents the Scherrer constant (0.94), λ represents the wavelength of CuKα rays (0.15418 nm), β represents the full width at half-maximum (WHM) in radians, and θ represents the Bragg angle in radians.

[0142] [Programmed Temperature Desorption Analysis] Temperature-programmed desorption (TPD) analysis was performed on the carbon catalysts of each embodiment using a temperature-programmed desorption analyzer (high-temperature TPD analyzer) capable of raising the temperature to 1,600°C. The high-temperature TPD analyzer is a device that uses high-frequency electromagnetic induction heating to heat the graphite crucible used as the host to be heated to 1,600°C or higher. Details of the high-temperature TPD analyzer are described in the journal Carbon (Takafumi Ishi, Susumu Kashihara, Yasuto Hoshikawa, Jun-ichi Ozaki, Naokatsu Kannari, Kazuyuki Takai, Toshiaki Enoki, Takashi Kyotani, Carbon, Volume 80, December 2014, pages 135-145).

[0143] The carbon catalyst was placed in a high-temperature TPD analyzer. At 5 × 10⁻⁶... -5 The carbon catalyst was heated under a high vacuum of Pa or lower, and the desorbed gas was measured using a quadrupole mass spectrometer (QMS).

[0144] Specifically, first, a graphite crucible was filled with 1 mg of carbon catalyst and placed in a quartz reaction tube connected to a high-temperature TPD analyzer. Then, the analyzer was evacuated using a turbomolecular pump until the pressure reached 5 × 10⁻⁶. -5Pa. Then, the temperature was increased from room temperature to 1,600°C at a rate of 10°C / min. During the temperature increase, the desorbed gas was detected, and the correlation between temperature (horizontal axis) and detection intensity (vertical axis) was recorded. The amount of desorbed gas was then determined. That is, the integral value (detection intensity area) of the detection intensity of the gas from the initial room temperature of the heat treatment to the measured temperature (1,600°C) was calculated.

[0145] On the other hand, a calibration curve showing the correlation between the amount of gas desorption and the detection intensity area was prepared using a predetermined amount of standard gas. When analyzing the desorbed gas from the sample using QMS, the fragment intensity ratio of various gaseous substances (H2, H2O, CO, CO2, N2, HCN, O2, CH4, C2H6, C3H6, and C3H8) was studied and used in the qualitative analysis of the desorbed gas to clearly distinguish gaseous substances of the same mass in the desorbed gas (substances with a mass number of 28 can be CO, N2, C2H4, etc.). Then, the amount of gas desorbed (released) from the carbon catalyst was determined based on the detection intensity area obtained through this measurement, as well as the calibration curve and the fragment intensity ratio. To verify the adequacy of the formed calibration curve, measurements were performed on a Ketjen black EC600JD (Lion Specialty Chemicals Co., Ltd.), and it was found that the amount of edge hydrogen fell within the range of 1,000 μmol / g to 1,500 μmol / g.

[0146] In this paper, the actual size of the carbon network forming carbon can be evaluated based on the average carbon network size L determined by the amount of carbon edge sites. In an embodiment of the invention, the total amount of carbon edge sites in the carbon catalyst is calculated based on the quantitative determination of desorbed gas during high-temperature TPD of the carbon catalyst, and using... Figure 1 The halo-benzene model shown calculates the average carbon network surface size L determined by this quantity. Figure 1 In the equation shown, a0 represents the lattice constant of the graphite crystal along the a-axis, which is 0.2461 nm.

[0147] It is known that the phenolic hydroxyl group of oxygen-containing compounds decomposes into carbon monoxide upon heating, leaving hydrogen atoms originating from the hydroxyl group at the carbon edge site. Therefore, the amount of hydrogen measured by high-temperature TPD can include the contribution of hydrogen originating from the phenolic hydroxyl group.

[0148] Both ethers (-O) and phenolic hydroxyl groups (-OH) are functional groups that desorb CO around 700 °C. After the phenolic hydroxyl group has desorbed CO, the H group remains at an edge position. Therefore, phenolic hydroxyl groups desorb CO at 1,000 °C or higher, followed by H2 desorption. The difference between phenolic hydroxyl groups and ethers is that phenolic hydroxyl groups desorb two gaseous substances (CO and H2) from a single functional group. Ethers and phenolic hydroxyl groups cannot be distinguished based on CO desorption observed by TPD analysis.

[0149] Therefore, to accurately calculate the total number of edge sites, both ethers and phenolic hydroxyl groups need to be considered. Given the above, in high-temperature TPD, it is assumed that ethers (-O-) desorb as CO. Meanwhile, although phenolic hydroxyl groups (-OH) actually desorb as both CO and H2, the number of edge sites is overestimated when both gases are considered simultaneously. Therefore, it is assumed that phenolic hydroxyl groups (-OH) desorb as H2. The total number of edge sites (N) of the carbon catalyst... 边缘 The possible values ​​of ) are calculated by the following two equations.

[0150] That is, the lower limit N of the total number of marginal sites. 边缘 (Min) is calculated by the following equation: N 边缘 (Min)[μmol / g] = CO2[μmol / g] + H2[μmol / g]×2 + N2[μmol / g]×2 + HCN[μmol / g]×2. The upper limit N of the total amount at the edge sites. 边缘 (Max) is calculated by the following equation: N 边缘 (Max)[μmol / g] = CO[μmol / g] + CO2[μmol / g] + H2[μmol / g]×2 + N2[μmol / g]×2 + HCN[μmol / g]×2. In the equation, CO[μmol / g], CO2[μmol / g], H2[μmol / g], N2[μmol / g], and HCN[μmol / g] are the amounts of desorbed gases—carbon monoxide, carbon dioxide, hydrogen, nitrogen, and hydrogen cyanide—determined by high-temperature TPD, respectively.

[0151] On the other hand, the average carbon network size L is determined by the following equation using the atomic weight of carbon (12 g / mol) and the lattice constant of graphite crystal in the a-axis direction (0.2461 nm): L[nm] = 2 × 1 / 12 × 0.2461 / N 边缘 [mol / g]. In this paper, the maximum value "L(Max)" and the minimum value "L(Min)" of L are calculated by the following two equations: "L(Max)" [nm] = 2 × 1 / 12 × 0.2461 / N 边缘 (Min) [mol / g]; and “L(Min)” [nm] = 2 × 1 / 12 × 0.2461 / N 边缘(Max) [mol / g].

[0152] As described above, since ethers and phenolic hydroxyl groups cannot be distinguished, two values, a maximum and a minimum, are calculated for the average carbon network size L. Although "L(Max)" is the value for the case where only phenolic hydroxyl groups are present, and "L(Min)" is the value for the case where only ethers are present, actual carbon materials are unlikely to have only one of phenolic hydroxyl groups or ethers. Therefore, in embodiments of the present invention, the average carbon network size L of the carbon catalyst is defined as the median value "L(av.)" of "L(Max)" and "L(Min)". That is, "L(av.)" is calculated by dividing the sum of "L(Min)" (obtained as the minimum possible value of the average carbon network size L) and "L(Max)" (obtained as the maximum possible value) by 2. "L(av.)" is obtained as the average carbon network size L of the carbon catalyst.

[0153] X-ray photoelectron spectroscopy (XPS) The photoelectron spectra of the core levels of carbon, nitrogen, oxygen, chlorine, and metal atoms derived from the raw materials (metal atoms in the carbonized raw materials used to produce the carbon catalyst) on the surface of each embodiment were measured using an X-ray photoelectron spectrometer (AXIS NOVA, manufactured by Kratos Analytical Limited). AlKα rays (10 mA, 15 kV, pass energy: 40 eV) were used as the X-ray source. The resulting photoelectron spectra were corrected for binding energies so that the peak of the C1s peak originating from the 1s orbital of the carbon atom was located at 284.5 eV.

[0154] In XPS wide-scan analysis, the atomic concentrations (atomic %) of carbon, nitrogen, oxygen, chlorine, and metal atoms derived from the raw materials on the carbon catalyst surface were determined based on the peak area and detection sensitivity factor in the photoelectron spectroscopy. The N / C ratio was then calculated by dividing the nitrogen atomic concentration (atomic %) by the carbon atomic concentration (atomic %). The Cl / C ratio, as the halogen / C ratio, was calculated by dividing the chlorine atomic concentration (atomic %) by the carbon atomic concentration (atomic %). The atomic concentration (atomic %) calculations were performed under the assumption that the carbon catalyst contains carbon, nitrogen, oxygen, chlorine, and metal atoms derived from the raw materials. The background for quantitative calculations was determined using the Shirley method.

[0155] Furthermore, peak separation of the N1s spectrum was performed in the obtained XPS spectrum. That is, the N1s spectrum with peaks in the range of 389 eV or greater to 410 eV or less was separated into: (1) a peak with a peak in the range of 398.5 ± 0.3 eV and a full width at half maximum (WHM) of 1.4 eV (pyridine nitrogen atom peak); (2) a peak with a peak in the range of 400.5 ± 0.3 eV and a full width at half maximum (WHM) of 1.4 eV (pyrrole / pyridone nitrogen atom peak); (3) a peak with a peak in the range of 401.5 ± 0.3 eV and a full width at half maximum (WHM) of 1.4 eV (quaternary ammonium nitrogen atom peak); and (4) a peak with a peak in the range of 402.5 ± 0.3 eV and a full width at half maximum (WHM) of 2.0 eV (oxidized nitrogen atom peak).

[0156] Specifically, the separation of the N1s spectrum is performed by approximating overlapping peaks through the superposition of Gaussian-Lorentz fundamental waveforms. The energy spectrum, subjected to energy value correction and intensity correction (described later), is optimized using peak intensity and peak position as parameters, serving as the Gaussian-Lorentz functions for each component, and peak separation is performed by curve fitting each of the aforementioned four overlapping peaks in the N1s spectrum. Curve fitting is performed to minimize the sum of squared residuals. In this paper, the term "squared residual" refers to the square of the residual at each measured energy value, and the term "sum of squared residuals" refers to the sum of these squared residuals. The term "residual" refers to the difference between the intensity of the N1s spectrum in the corrected energy spectrum and the sum of the intensities of the four separated peaks.

[0157] Regarding correction, firstly, energy correction is performed on the XPS spectra obtained through XPS measurements. Measurements of carbon atoms originating from C1s are used for energy correction. When the normal value (284.5 eV) of the C1s peak peak deviates from the measured peak peak, the value obtained by subtracting the measured C1s peak value from the normal value is added to the binding energy of the N1s spectrum. Next, intensity correction is performed. Intensity correction is performed by subtracting the background intensity determined by the Shirley method from the spectral intensity obtained through energy correction. Peak separation is then performed using the spectrum obtained through this correction.

[0158] Then, calculate the percentage (%) of the area of ​​each of the four peaks obtained through peak separation (i.e., pyridine nitrogen peak, pyrrole / pyridone nitrogen peak, quaternary ammonium nitrogen peak, and oxidized nitrogen peak) to the total area of ​​the four peaks.

[0159] [Specific surface area] The specific surface area of ​​the carbon catalyst in each embodiment was measured by nitrogen adsorption using a specific surface area-pore distribution measuring device (BELSORP MINI X, manufactured by MicrotracBEL Corp.). Specifically, firstly, 0.03 g of carbon catalyst was heated at 200 °C and 6.7 × 10⁻⁶ ppm. -2The carbon catalyst was held at 2 Pa for 2 hours to remove water adsorbed onto it. Next, a nitrogen adsorption isotherm at 77 K was obtained using the BET method. The nitrogen adsorption isotherm at 77 K was obtained by measuring the change in the amount of nitrogen adsorbed onto the carbon catalyst in relation to the pressure change of nitrogen gas at 77 K. Then, the BET specific surface area (m²) of the carbon catalyst obtained using the nitrogen adsorption method was obtained from the nitrogen adsorption isotherm at 77 K. 2 / g).

[0160] [Evaluation of catalytic activity and durability] The catalytic activity of each 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-channel electrochemical analyzer (CHI700C manufactured by ALS Co., Ltd.).

[0161] First, a rotating ring-disc electrode apparatus with a three-electrode system including working electrodes for each carbon catalyst was fabricated. Specifically, 5 mg of carbon catalyst, 50 μL of 5% NAFION (trademark) (manufactured by Sigma-Aldrich, NAFION perfluorinated ion exchange resin, 5% solution (product number: 510211)), 400 μL of water, and 100 μL of isopropanol were mixed to prepare a slurry. Next, the slurry was sonicated for 10 minutes and then homogenized for 2 minutes. Then, the resulting slurry was coated onto the working electrode (a ring-disc electrode for RRDE-3A manufactured by BAS Inc., carbon ring-gold disk electrode, disk diameter: 4 mm), such that the carbon catalyst content per unit electrode area was 0.2 mg / cm². 2 Then it is dried to produce a working electrode containing the carbon catalyst supported thereon.

[0162] Carbon electrode (glass carbon rod manufactured by BAS Inc.) A 2mm × 100mm electrode was used as the counter electrode, and a reversible hydrogen electrode (RHE) (a storage-type reversible hydrogen electrode manufactured by EC Frontier Co., Ltd.) was used as the reference electrode. Thus, a rotating ring-disc electrode apparatus comprising a working electrode with a carbon catalyst, a carbon electrode used as the counter electrode, and a reversible hydrogen electrode (RHE) used as the reference electrode was obtained. A 0.05 M sulfuric acid aqueous solution was used as the electrolyte.

[0163] Then, the catalytic activity of each carbon catalyst was measured using the aforementioned rotating ring-disc electrode apparatus. Specifically, linear sweep voltammetry (N2-LSV) and linear sweep voltammetry (O2-LSV) were performed using the rotating ring-disc electrode apparatus, which has a three-electrode system including the working electrode of each carbon catalyst.

[0164] In N2-LSV, nitrogen bubbling is first performed for 10 minutes to remove oxygen from the electrolyte. Afterward, the electrode is rotated at 1,600 rpm, and the current density at a scan rate of 20 mV / s during potential scanning is recorded as a function of potential (N2-LSV function).

[0165] Following the N2-LSV described above, in the O2-LSV, oxygen was first bubbled for 10 minutes to saturate the electrolyte with oxygen. Afterward, the electrode was rotated at 1,600 rpm, and the current density at a scan rate of 20 mV / s during potential scanning was recorded as a function of potential (O2-LSV function).

[0166] Then, the oxygen reduction voltammogram is obtained by subtracting the N2-LSV function from the O2-LSV function, which was obtained as described above. In the resulting oxygen reduction voltammogram, the positive and negative signs are placed before the numerical values, so that the reduction current has a negative value and the oxidation current has a positive value.

[0167] From the oxygen reduction voltammetry obtained therefrom, the value was recorded at -10 μA / cm. 2 The voltage at which the reduction current flows (oxygen reduction initiation potential E) O2 (V vs. NHE) serves as an indicator of the catalytic activity of each carbon catalyst.

[0168] The durability of the carbon catalyst was evaluated similarly using a rotating ring-disk electrode apparatus and a dual electrochemical analyzer. Specifically, firstly, oxygen reduction voltammetry was obtained in the same manner as the catalytic activity evaluation described above. Then, from the obtained oxygen reduction voltammetry, the current density (current density before degradation) at 0.3 V (vs. NHE) was recorded (mA / cm²). 2 (), which serves as an indicator of the number of catalytic active sites in the carbon catalyst before the degradation acceleration test.

[0169] Subsequently, accelerated degradation tests were continuously performed using the aforementioned working electrode for measuring the current density before degradation. Specifically, a cyclic voltammetry (start-stop test) was conducted for 100 cycles at 0.5 V / s under a nitrogen atmosphere, in the range of 1.0 V to 1.5 V.

[0170] In addition, after the above start-up-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 the measurement of the current density before degradation. Then, the current density (mA / cm²) at 0.3 V (vs. NHE) was recorded from the obtained oxygen reduction voltammogram. 2 (Deteriorated current density) serves as an indicator of the number of catalytically active sites on the carbon catalyst after accelerated degradation testing. Durability (%) is calculated by dividing the resulting deteriorated current density by the pre-deteriorated current density and multiplying the result by 100.

[0171] [result] Figure 2 The evaluation results of the properties of the carbon catalysts in each embodiment are shown. For example... Figure 2 As shown, the catalytic activity (E) of each carbon catalyst in Examples 1 to 4 is... O2 (V vs. NHE) showed higher catalytic activity than each carbon catalyst in Examples C2 and C3. In these examples, the catalytic activity of each carbon catalyst in Examples 2 through 4 was higher than that of each carbon catalyst in Examples C1 through C3. In particular, the carbon catalyst of Example 2 exhibited significantly higher catalytic activity.

[0172] The durability (%) of each carbon catalyst in Examples 1 to 4 was significantly higher than that of each carbon catalyst in Examples C1 to C3. That is, the carbon catalysts in Examples 1 to 4 each have high catalytic activity and high durability.

[0173] The carbon catalysts of Examples 1 to 4 each have a significantly larger L / La ratio than the carbon catalysts of Examples C1 to C3. In this study, the grain size La of the carbon catalysts of Examples 1 to 4 is not significantly different from that of the carbon catalysts of Examples C1 to C3. In contrast, the average carbon network size L of each carbon catalyst of Examples 1 to 4 is significantly larger than that of the carbon catalysts of Examples C1 to C3. The grain size Lc of the carbon catalysts of Examples 1 to 4 is not significantly different from that of the carbon catalysts of Examples C1 to C3. The carbon catalyst of Example C1 has a significantly larger BET specific surface area, and the carbon catalyst of Example 1 has the smallest BET specific surface area.

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

[0175] In contrast, the chlorine atom concentration (Cl (atomic %)) of each carbon catalyst in Examples 1 to 4 is less than that of the carbon catalysts in Examples C1 to C3. In this regard, it is conceivable that the average carbon network size L of each carbon structure in the carbon catalysts of Examples 1 to 4 is greater than that of the carbon network size L of the carbon catalysts in Examples C1 to C3, and the number of edge sites on their carbon network is smaller. Therefore, the amount of chlorine atoms introduced into the edge sites of each carbon catalyst in Examples 1 to 4 becomes less than the amount of chlorine atoms in the edge sites of the carbon catalysts in Examples C1 to C3.

[0176] The nitrogen atom concentration (N (atomic %)) of each carbon catalyst in Examples 1 to 4 is less than that of the carbon catalysts in Examples C1 to C3. This difference is believed to be caused by differences in the following: the carbonization temperature during the production of the carbon catalyst; and the amount of nitrogen atoms in the carbonization feedstock used in the production.

[0177] The N / C ratio and Cl / C ratio of each carbon catalyst in Examples 1 to 4 are smaller than those of the carbon catalysts in Examples C1 to C3 because the nitrogen atom concentration (N (atomic %)) and chlorine atom concentration (Cl (atomic %)) of each carbon catalyst in Examples 1 to 4 are smaller, as stated above.

[0178] Regarding the type of nitrogen atoms in the carbon catalyst, although the carbon catalysts of Examples 1 to 4 each contain quaternary ammonium nitrogen atoms, the carbon catalysts of Examples C1 to C3 each do not contain any quaternary ammonium nitrogen atoms. Specifically, the percentage of quaternary ammonium nitrogen in each carbon catalyst of Examples 1 to 4 (“Quaternary Ammonium Percentage (%)” in the chart) is 7.0% or greater, which is the percentage of its quaternary ammonium nitrogen atom concentration (atomic %) to its nitrogen atom concentration (total nitrogen atom concentration) (N (atomic %)).

[0179] Meanwhile, the percentage of pyridine nitrogen in each of the carbon catalysts in Examples 1 to 4 (“Pyridine percentage (%)” in the chart) is less than the percentage of pyridine nitrogen in the carbon catalysts in Examples C1 to C3, which is the percentage of its pyridine nitrogen atom concentration (atoms) to its nitrogen atom concentration (N (atoms)).

[0180] It is conceivable that the differences in the percentage of quaternary ammonium nitrogen atoms and the percentage of pyridine nitrogen atoms are caused by the fact that the carbon structures in the carbon catalysts of Examples 1 to 4 each have relatively large L / La ratios.

Claims

1. A carbon catalyst, wherein the L / La ratio of the carbon catalyst is 18 or greater, the L / La ratio being the ratio of the average carbon network size L obtained by temperature-programmed desorption analysis capable of reaching 1,600 °C to the grain size La obtained by the diffraction peak near a diffraction angle (2θ) in an X-ray diffraction pattern obtained by powder X-ray diffraction using CuKα rays, and wherein the ratio of the halogen atom concentration (atomic%) to the carbon atom concentration (atomic%) of the carbon catalyst obtained by X-ray photoelectron spectroscopy is 0.0005 or greater.

2. The carbon catalyst according to claim 1, wherein the average carbon network size L is 5 nm or greater.

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

4. The carbon catalyst according to claim 1, wherein the carbon catalyst comprises nitrogen atoms.

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

6. The carbon catalyst according to claim 1, wherein the area of ​​the quaternary ammonium nitrogen atom peak of the carbon catalyst is 0.1% or greater relative to the total area of ​​the following four nitrogen atom peaks, said percentage being obtained by peak separation of the N1s spectrum obtained by X-ray photoelectron spectroscopy into said four nitrogen atom peaks: (1) It has a pyridine-type nitrogen atom peak with a peak in the range of 398.5±0.3 eV and a full width at half maximum of 1.4 eV; (2) It has a pyrrole / pyridinone type nitrogen atom peak with a peak in the range of 400.5±0.3 eV and a full width at half maximum of 1.4 eV; (3) A quaternary ammonium nitrogen atom peak with a peak in the range of 401.5 ± 0.3 eV and a full width at half maximum (WHM) of 1.4 eV; and (4) It has an oxide nitrogen atom peak with a peak in the range of 402.5±0.3 eV and a full width at half maximum of 2.0 eV.

7. The carbon catalyst according to claim 1, wherein the BET specific surface area of ​​the carbon catalyst obtained by nitrogen adsorption is 50 m². 2 / g or larger.

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

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

Images