Electrode catalyst for a fuel cell and method for its production, and cathode, anode and fuel cell containing the electrode catalyst

Abstract

Electrode catalyst for a fuel cell, comprising: a carbon carrier; and a catalytic metal carried on the carbon support, wherein the catalytic metal is selected from platinum or a platinum alloy, wherein the carbon support has a crystallite size of the (002) plane of carbon in a range of 5.0 nm or more, at least pores with an average radius of 1.0 nm to 2.5 nm, and a specific surface area in a range of 95 m 2 / g up to 170 m 2 / g has, and the catalytic metal has a crystallite size of the (220) plane of platinum in a range of 4.5 nm or less.

Description

BACKGROUND OF THE INVENTION 1. Field of the invention

[0001] The present invention relates to an electrode catalyst for a fuel cell and a method for its production; and to a cathode, anode and fuel cell comprising the electrode catalyst. 2. Description of the related prior art

[0002] In a fuel cell, hydrogen reacts electrochemically with oxygen to generate energy. In principle, a fuel cell produces only water as a byproduct, in addition to generating energy. Consequently, the fuel cell has gained attention as a system for generating clean energy that essentially poses no burden on the global environment.

[0003] In a fuel cell, an electromotive force is generated by supplying an anode (fuel electrode) with hydrogen-containing fuel gas and a cathode (air electrode) with oxygen-containing oxidizing gas. An oxidation reaction takes place on the anode, represented by the following formula (1), while a reduction reaction occurs on the cathode, represented by the following formula (2), resulting in an overall reaction represented by the following formula (3). Consequently, an electromotive force is supplied to an external circuit. H2→2H + +2e - (1) (1 / 2)O2+2H + +2e - →H2O (2) H2 + (1 / 2)O2 → H2O (3)

[0004] Depending on the type of electrolyte, fuel cells are classified, for example, into polymer electrolyte fuel cells (PEFC), phosphoric acid fuel cells (PAFC), molten carbonate fuel cells (MCFC), and solid oxide fuel cells (SOFC). In PEFC and PAFC fuel cells, an electrode catalyst is generally used, which comprises: a conductive support, such as a carbon support; and particles of a catalytic metal, such as platinum or a platinum alloy, which are mounted on the conductive support.

[0005] Under the operating conditions of a fuel cell, the carbon support of the electrode catalyst is electrochemically oxidized by a reaction represented by the following formula (4). Parallel to the oxidation reaction, carbon dioxide, which results from a transformation of carbon atoms forming the carbon support, is separated from the carbon support. C + 2H2O → CO2 + 4H + +4e - (4)

[0006] The oxidation-reduction potential of the reaction represented by equation (4) is approximately 0.2 V. Therefore, the reaction represented by equation (4) can proceed slowly under the operating conditions of a fuel cell. Consequently, during prolonged operation of a fuel cell, electrode thinning and a decrease in the amount of carbon in the carbon support can be observed. This electrode thinning can result in reduced fuel cell performance.

[0007] Typically, the carbon support used in the electrode catalyst has a large specific surface area, i.e., a low-crystalline graphite structure on its surface. The particles of the catalytic metal can be carried with high dispersibility on the surface with a large specific surface area. Accordingly, the mass activity of an electrode catalyst obtained as a product can be improved by using the carbon support with a large specific surface area. Furthermore, the course of the reaction represented by formula (4) is inhibited by carbon with a high-crystalline graphite structure. Therefore, a carbon support with a high-crystalline graphite structure generally exhibits high resistance to the oxidation reaction represented by formula (4).

[0008] To increase the specific surface area of ​​a carbon support, it is necessary to modify its surface structure. However, modifying the surface structure can disrupt the graphite structure on the carbon support's surface. This means that the oxidation resistance of a carbon support can decrease due to an increase in its specific surface area. Therefore, techniques for using highly crystalline carbon supports in an electrode catalyst for a fuel cell have been developed.

[0009] For example, International Publication WO 2005 / 106994 A1 describes: a cathode catalyst layer containing a cathode catalyst incorporating platinum or a platinum alloy, a conductive carbon material supporting the cathode catalyst, and a proton-conducting polymer electrolyte; and an anode catalyst layer containing an anode catalyst, a conductive carbon material supporting the anode catalyst, and a proton-conducting polymer electrolyte. This document also describes that the conductive carbon material of the cathode catalyst layer contains graphitized carbon black, and that the BET surface area of ​​the carbon black is 100 m². 2 / g up to 300 m 2 / g.

[0010] Japanese patent application publication no. 2000-268828 (JP 2000-268828 A) describes a polymer electrolyte fuel cell comprising: a gas diffusion electrode containing an electrode catalyst in which platinum or a platinum alloy is supported on a carbon substrate; and an electrolyte formed from an ion-exchange resin having an average lattice plane spacing d 002 the

[002] plane of the carbon support is 0.337 nm to 0.348 nm, a crystallite size Lc (002) The carbon support has a diameter of 3 nm to 18 nm and a specific surface area of ​​70 m². 2 / g up to 800 m 2 / g is.

[0011] Japanese patent application publication no. 2001-357857 (JP 2001-357857 A) describes a polymer electrolyte fuel cell comprising: an ion-exchange membrane; and a cathode and an anode arranged opposite each other through the ion-exchange membrane. The cathode contains an electrode catalyst in which platinum or a platinum alloy is supported on a carbon substrate; and an ion-exchange resin in which an average lattice plane spacing d, calculated from X-ray diffraction, is applied. 002 the

[002] plane of the carbon support is 0.340 nm to 0.362 nm, a crystallite size Lc of the carbon support is 0.6 nm to 4 nm and a specific surface area of ​​the carbon support is 260 m² 2 / g up to 800 m 2 / g is.

[0012] Japanese patent application publication no. 2006-179463 (JP 2006-179463 A) describes a polymer electrolyte fuel cell comprising: a solid polymer electrolyte membrane; catalyst layers arranged on both sides of the solid polymer electrolyte membrane; gas diffusion layers arranged outside the catalyst layers; and separators arranged outside the gas diffusion layers, wherein a cathode-side catalyst layer of the catalyst layers comprises: a carbon-containing carbon support in which an average lattice plane spacing d calculated by X-ray diffraction is used. 002 the

[002] plane is 0.343 nm to 0.358 nm, a crystallite size Lc is 3 nm to 10 nm and a specific surface area is 200 m² 2 / g up to 300 m 2 / g is; platinum-containing catalyst particles carried on the carbon support; and an electrolyte.

[0013] Japanese patent application publication no. 2010-102889 (JP 2010-102889 A) describes an electrode catalyst for a fuel cell in which a catalytic metal is supported on a highly crystalline carbon support with a carbon crystallinity ranging from 57% to 90%. JP 2010-102889 A specifies that the crystallite size Lc of the highly crystalline carbon is 2.3 nm or greater.

[0014] Japanese patent application publication no. 2008-41253 (JP 2008-41253 A) describes an electrode catalyst comprising: catalytic metal particles with an average crystallite size of 1 nm to 4 nm; and a carbon material supporting the catalytic metal particles, wherein the carbon material exhibits an intensity ratio R=I as measured by Raman spectroscopy D / I G a peak intensity I D the D-band to a peak intensity I G the G-band is 0.9 to 1.2.

[0015] Furthermore, US 2007 / 0 298 304 A1, JP 2010-092799 A, DE 103 46 334 A1, US 2009 / 0 208 780 A1, US 2011 / 0 014 550 A1, US 2010 / 0 297 524 A1 and DE 699 00 256 T2 disclose electrode catalysts for fuel cells from the prior art.

[0016] As described above, techniques for using a highly crystalline carbon support in an electrode catalyst for a fuel cell have been developed. However, if the crystallinity of a carbon support is improved to enhance its oxidation resistance, the specific surface area may decrease. It is established that there is a relationship between the specific surface area of ​​a carbon support and the number of catalytic metal carrier sites within the carbon support. If the specific surface area of ​​a carbon support decreases, the dispersibility of the catalytic metal carried on the carbon support may decrease. In this case, the mass activity of the resulting electrode catalyst may decrease.As described above, in an electrode catalyst for a fuel cell using a highly crystalline carbon support, there is room for improvement in performance with respect to mass activity and durability. SUMMARY OF THE INVENTION

[0017] The invention was made to provide a technique for achieving both high mass activity and high durability of an electrode catalyst for a fuel cell.

[0018] The present inventors have found that both the mass activity and the stability can be improved by causing a catalytic metal to be carried on a carbon support obtained by oxidizing a carbon support material under predetermined conditions, which completes the invention.

[0019] According to a first aspect of the invention, an electrode catalyst for a fuel cell is provided, comprising: a carbon support; and a catalytic metal carried on the carbon support, wherein the catalytic metal is selected from platinum or a platinum alloy. The carbon support has a crystallite size (Lc) of the (002) plane of carbon in a range of 5.0 nm or more, at least pores with an average radius of 1.0 nm to 2.5 nm, and a specific surface area in a range of 95 m². 2 / g up to 170 m 2 / g, and the catalytic metal exhibits a crystallite size of the (220) plane of platinum in a range of 4.5 nm or less.

[0020] An intensity ratio of a peak intensity I D the D-band to a peak intensity I G The G-band can be lower than 0.9 in a Raman spectrum of the carbon support.

[0021] The catalytic metal can be platinum and can have a CO adsorption quantity of 24 ml / g Pt or more.

[0022] The catalytic metal can be a platinum alloy and can have a CO adsorption quantity of 18 ml / g Pt or more.

[0023] The amount of carrier metal of the catalytic metal can range from 15 wt% or wt% to 35 wt% based on the total mass of the electrode catalyst.

[0024] The amount of carrier metal of the catalytic metal can be greater than or equal to 4.5 wt% and less than 15 wt% based on the total mass of the electrode catalyst.

[0025] According to a second aspect of the invention, a cathode is provided which includes the electrode catalyst described above.

[0026] According to a third aspect of the invention, an anode is provided which includes the electrode catalyst described above.

[0027] According to a fourth aspect of the invention, a fuel cell is provided which includes the cathode according to the second aspect and / or the anode according to the third aspect.

[0028] According to a fifth aspect of the invention, a method for producing the electrode catalyst according to the first aspect is provided. This method comprises: oxidizing a carbon support material by thermally oxidizing the carbon support material in a temperature range of 580°C to 650°C in the presence of oxygen or by treating the carbon support material with an oxidizing agent such that a carbon support is obtained having a crystallite size (Lc) of the (002) plane of carbon in a range of 5.0 nm or more, at least pores with an average radius of 1.0 nm to 2.5 nm, and a specific surface area in a range of 95 m². 2 / g up to 170 m 2 / g; and causing the obtained carbon support and a catalytic metal material selected from platinum and a platinum alloy to react with each other in such a way that catalytic metal is deposited onto the carbon support.

[0029] The oxidizing agent may contain potassium permanganate.

[0030] The amount of oxidizing agent can range from 2.5 mol% to 14.5 mol% based on the total number of moles of carbon atoms in the carbon support material.

[0031] According to the invention, both a high mass activity and a high durability of an electrode catalyst for a fuel cell can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Features, advantages, and the technical and industrial significance of exemplary embodiments of the invention are described below with reference to the accompanying drawings, in which the same reference numerals denote the same elements. It shows: Fig. 1A and Fig. 1B are transmission electron microscopy (TEM) images showing a surface of a carbon support material (TOCA BLACK #3855), where Fig. 1A the image is at a scale bar of 5 nm, and Fig. 1B the image is at a scale bar of 10 nm; Fig. 2A and Fig. 2B are transmission electron microscopy (TEM) images showing a surface of a carbon support material after completion of an oxidation step in a process for producing an electrode catalyst for a fuel cell according to an embodiment of the invention, wherein Fig. 2A is the TEM image showing the carbon support after carrying out the oxidation step by treatment with an oxidizing agent under the same conditions as in Examples 1-1-7, 1-1-8, 1-2-2, 1-2-5 and 1-2-7, and Fig. 2B is the TEM image showing the carbon support after carrying out the oxidation step by thermal oxidation under the same conditions as in Examples 1-1-12, 1-1-13, 1-2-10 and 1-2-11; Fig. Sections 3A to 3C show a summary of the manufacturing conditions for electrode catalysts from examples and comparative examples; Fig. Sections 4A to 4C show physical properties of electrode catalysts using examples and comparative examples; Fig. Figure 5 is a diagram showing a relationship between the specific surface area of ​​a carbon support and the CO adsorption quantity of each of the platinum-supported electrode catalysts of Examples 1-1-1 to 1-1-16 and the comparison examples 1-1-1 to 1-1-12; Fig. Figure 6 is a diagram showing a relationship between the crystallite size (Lc) of the (002) plane of carbon of a carbon support and the CO adsorption quantity of each of the platinum-supported electrode catalysts of Examples 1-1-1 to 1-1-16 and the comparison examples 1-1-1 to 1-1-12; Fig. Figure 7 is a diagram showing a relationship between the intensity ratio of a peak intensity I D the D-band to a peak intensity I G the G band in a Raman spectrum of a carbon support and the CO adsorption quantity of each of the platinum-supported electrode catalysts of Examples 1-1-1 to 1-1-16 and the comparison examples 1-1-1 to 1-1-12 shows; Fig. Figure 8 is a diagram showing a relationship between the crystallite size of the (220) plane of platinum of a catalytic metal and the CO adsorption quantity of each of the platinum-supported electrode catalysts of Examples 1-1-1 to 1-1-16 and the comparison examples 1-1-1 to 1-1-12; Fig. Figure 9 is a diagram showing a relationship between the amount of CO adsorption and the maintenance of an electrochemically active surface (ECSA) of each of the platinum-supported electrode catalysts of Examples 1-1-1 to 1-1-16 and the comparison examples 1-1-1 to 1-1-12; Fig. Figure 10 is a diagram showing a relationship between the specific surface area of ​​a carbon support and the CO adsorption quantity of each platinum alloy-supported electrode catalyst of Examples 1-2-1 to 1-2-14 and the comparison examples 1-2-1 to 1-2-5; Fig. Figure 11 is a diagram showing a relationship between the crystallite size (Lc) of the (002) plane of carbon of a carbon support and the CO adsorption quantity of each of the platinum alloy-supported electrode catalysts of Examples 1-2-1 to 1-2-14 and the comparison examples 1-2-1 to 1-2-5; Fig. Figure 12 is a diagram showing a relationship between the intensity ratio of a peak intensity I D the D-band to a peak intensity I G the G-band in a Raman spectrum of a carbon support and the CO adsorption quantity of each of the platinum alloy-supported electrode catalysts of Examples 1-2-1 to 1-2-14 and the comparison examples 1-2-1 to 1-2-5 shows; Fig. Figure 13 is a diagram showing a relationship between the crystallite size of the (220) plane of platinum of a catalytic metal and the CO adsorption quantity of each of the platinum alloy-supported electrode catalysts of Examples 1-2-1 to 1-2-14 and the comparison examples 1-2-1 to 1-2-5; Fig. Figure 14 is a diagram showing a relationship between the amount of CO adsorption and the maintenance of the ECSA of each of the platinum alloy-supported electrode catalysts of Examples 1-2-1 to 1-2-14 and the comparison examples 1-2-1 to 1-2-5; Fig. Figure 15 is a diagram showing the pore distribution of a carbon support before thermal oxidation, after thermal oxidation at 600°C, after thermal oxidation at 610°C, after thermal oxidation at 620°C and after thermal oxidation at 630°C; Fig. Figure 16 is a diagram showing a relationship between the temperature of a thermal oxidation of a carbon support material and the pore volume of a carbon support obtained as a product; Fig. Figure 17 is a diagram showing a relationship between the temperature of a thermal oxidation of a carbon carrier in air and the temperature of a 5% mass reduction determined by thermogravimetric analysis; Fig. Figure 18 is a diagram showing a relationship between the temperature of a thermal oxidation of a carbon support in air, the amount of CO adsorption and the crystallite size of the (220) plane of platinum during the preparation of each of the platinum-supported electrode catalysts of Examples 1-1-11 to 1-1-16 and the comparison examples 1-1-10 to 1-1-12; Fig. Figure 19 is a diagram showing a relationship between the temperature of a thermal oxidation of a carbon support in air, the amount of CO adsorption and the specific surface area of ​​the carbon support during the preparation of each of the platinum-supported electrode catalysts of Examples 1-1-11 to 1-1-16 and the comparison examples 1-1-10 to 1-1-12; Fig. Figure 20 is a diagram showing a relationship between the temperature of a thermal oxidation of a carbon support in air, the amount of CO adsorption and the oxygen concentration in the carbon support during the preparation of each of the platinum-supported electrode catalysts of Examples 1-1-11 to 1-1-16 and the comparison examples 1-1-10 to 1-1-12; Fig. Figure 21 is a diagram showing a relationship between the temperature of a thermal oxidation of a carbon support in air, the amount of CO adsorption and the D / G ratio of the carbon support during the preparation of each of the platinum-supported electrode catalysts of Examples 1-1-11 to 1-1-16 and the comparison examples 1-1-10 to 1-1-12; Fig. Figure 22 is a diagram showing a relationship between the K / C ratio of a carbon support during treatment with an oxidizing agent (potassium permanganate), the amount of CO adsorption and the crystallite size of the (220) plane of platinum during the preparation of each of the platinum-supported electrode catalysts of Examples 1-1-1 to 1-1-10 and the comparison example 1-1-1; Fig. Figure 23 is a diagram showing a relationship between the K / C ratio of a carbon support during treatment with an oxidizing agent (potassium permanganate), the amount of CO adsorption and the specific surface area of ​​the carbon support during the preparation of each of the platinum alloy-supported electrode catalysts of Examples 1-1-1 to 1-1-10 and the comparison example 1-1-1; Fig. Figure 24 is a diagram showing a relationship between the K / C ratio of a carbon support during treatment with an oxidizing agent (potassium permanganate), the amount of CO adsorption, and the oxygen concentration in the carbon support during the preparation of each of the platinum-supported electrode catalysts of Examples 1-1-11 to 1-1-16 and the comparison examples 1-1-10 to 1-1-12; and Fig. Figure 25 is a diagram showing a relationship between the K / C ratio of a carbon support during treatment with an oxidizing agent (potassium permanganate), the amount of CO adsorption, and the D / G ratio of the carbon support during the preparation of each of the platinum-supported electrode catalysts of Examples 1-1-11 to 1-1-16 and the comparison examples 1-1-10 to 1-1-12. DETAILED DESCRIPTION OF EXECUTION FORMS

[0033] The following section describes embodiments of the invention in detail. 1. Electrode catalyst for a fuel cell

[0034] One embodiment of the present invention relates to an electrode catalyst for a fuel cell. This electrode catalyst for a fuel cell comprises: a carbon support; and a catalytic metal supported on the carbon support, wherein the catalytic metal is selected from platinum (Pt) or a platinum alloy.

[0035] In a prior art electrode catalyst for a fuel cell, a carbon support with a large specific surface area is used to improve the mass activity (current density per unit mass of the carbon support) by causing a catalytic metal to be carried with high dispersibility on the carbon support. Generally, a graphite crystal structure forms on the surface of a carbon support ( Fig. 1A and Fig. 1B). The higher the crystallinity of graphite, the greater the thickness of a graphite crystal layer. The thickness of the graphite crystal layer is expressed by a crystallite size (Lc) of the (002) plane of carbon, which is determined not only on the basis of a transmission electron microscopy (TEM) image, but also on the basis of an X-ray diffraction (XRD) spectrum.

[0036] The crystallinity of a carbon support can be assessed based on its Raman spectrum. It is known that a peak in the Raman spectrum of a carbon support occurs in a range of 1300 cm⁻¹. -1 up to 1400 cm -1 The observed peak (hereinafter also referred to as the "D-band peak") is due to a non-graphite structure, and a peak that extends over a range of 1500 cm². -1 up to 1600 cm -1The observed G-band peak (hereinafter also referred to as the "G-band peak") is due to a graphite structure. The full width at half maximum (FWHM) of the G-band peak can vary depending on the diversity of the graphite structure. It is assumed that the lower the G-band FWHM, the purer the graphite structure. Furthermore, it is assumed that the crystallinity is higher the lower the intensity ratio (D / G ratio) of a D-band peak intensity I. D to a G-band peak intensity I G is.

[0037] In a fuel cell electrode catalyst, the Lc and G-band FWHM of a carbon support are physical properties representing a graphite structure formed on the surface of the carbon support. Conversely, the D / G ratio of a carbon support is a physical property representing the abundance ratio of a graphite structure formed within the carbon support. Under fuel cell operating conditions, a carbon support is expected to oxidize more readily in a non-graphite structure than in a graphite structure. Furthermore, a graphite structure of a carbon support is expected to oxidize more readily in a low-crystalline region. When a carbon support in a fuel cell electrode catalyst is oxidized, catalytic metal particles may migrate and / or aggregate.If the catalytic metal particles of the electrode catalyst move and / or aggregate and become coarse-grained, the mass activity of the catalytic metal can decrease.

[0038] Therefore, it is assumed that the durability (e.g., high oxidation resistance) of an electrode catalyst for a fuel cell can be improved by increasing the abundance ratio of a graphite structure and using a highly crystalline carbon support. However, a highly crystalline carbon support generally has a small specific surface area. Consequently, it is difficult to achieve both high mass activity and high durability in an electrode catalyst for a fuel cell.

[0039] The present inventors have discovered that by oxidizing a carbon support material described below during the production of an electrode catalyst for a fuel cell, a carbon support with a specific surface area, a high proportion of graphite structure, and high crystallinity of the graphite structure can be obtained. By causing a catalytic metal to be supported on a carbon support with the properties described above, an electrode catalyst for a fuel cell can be obtained in which the catalytic material is supported with high dispersibility and which exhibits high oxidation resistance.

[0040] The degree of dispersion of the catalytic metal in the electrode catalyst for a fuel cell according to the embodiment can be assessed, for example, based on the amount of carbon monoxide (CO) adsorption by the electrode catalyst. The CO adsorption capacity of the electrode catalyst for a fuel cell can be determined, for example, using the following method. A predetermined quantity of the electrode catalyst is weighed into a container. The electrode catalyst in the container is reduced in a hydrogen atmosphere.

[0041] After completion of the reduction treatment, carbon monoxide is introduced into the container in a pulse, and the CO adsorption rate of each electrode catalyst is determined. Furthermore, the oxidation resistance of the carbon support in the electrode catalyst for a fuel cell can be assessed based on the maintenance of an electrochemically active surface area (ECSA) of the electrode catalyst. The maintenance of the ECSA of the electrode catalyst for a fuel cell can be determined, for example, using a rotating disk electrode method.

[0042] The carbon support included in the electrode catalyst for a fuel cell according to the embodiment has a crystallite size (Lc) of the (002) plane of carbon in the range of 5.0 nm or more. The Lc is preferably in the range of 5.0 nm to 5.5 nm and more preferably in the range of 5.1 nm to 5.5 nm. If the Lc of the carbon support included in the electrode catalyst for a fuel cell is in the range described above, the oxidation resistance is high, and / or the electrode catalyst in which the catalytic metal is supported with high dispersibility can be obtained.

[0043] The Lc can be determined, for example, using the following procedure. An X-ray diffractometer (XRD) is used to measure the XRD spectrum of the carbon support contained in the electrode catalyst for a fuel cell. Based on the obtained XRD spectrum, the crystallite size (Lc) of the (002) plane of carbon is determined using the Scherrer equation.

[0044] The carbon support included in the electrode catalyst for a fuel cell according to the embodiment has a specific surface area in a range of 95 m². 2 / g up to 170 m 2 The specific surface area is preferably in the range of 95 m². 2 / g up to 165 m 2 / g and even more preferably in an area of ​​125 m 2 / g up to 165 m 2 / g. Is the specific surface area of ​​the carbon support contained in the electrode catalyst for a fuel cell 95 m² 2 / g or greater, especially 125 m 2 / g or larger, the electrode catalyst can be obtained in which the catalytic metal is carried with high dispersibility.

[0045] The specific surface area can be determined using a device for measuring the specific surface area by measuring a specific BET surface area of ​​the carbon support contained in the electrode catalyst for a fuel cell based on a gas adsorption method.

[0046] The carbon support included in the electrode catalyst for a fuel cell according to the embodiment preferably has an intensity ratio (hereinafter also referred to as the “D / G” ratio) of a D-band peak intensity I D to a G-band peak intensity I Gin a Raman spectrum less than 0.9. The D / G ratio is preferably in the range of 0.5 to less than 0.9 and even more preferably in the range of 0.6 to less than 0.9. Furthermore, the full half-width of the G-band peak (hereinafter also referred to as "G-band FWHM") of the carbon support included in the electrode catalyst for a fuel cell according to the embodiment is preferably in the range of 30 cm⁻¹. -1 up to 50 cm -1 and even more preferably in an area of ​​33 cm -1 up to 42 cm -1 In the invention, "D-band peak" refers to a peak that occurs within a range of 1300 cm. -1 up to 1400 cm -1 is observed and typically has a maximum adsorption wavelength of 1360 cm -1 exhibits. Moreover, in the invention, "G-band peak" refers to a peak that occurs within a range of 1500 cm. -1 up to 1600 cm -1is observed and typically has a maximum adsorption wavelength of 1580 cm -1 exhibits. If, in the embodiment, the D / G ratio and the G-band FWHM of the carbon support contained in the electrode catalyst for a fuel cell are in the ranges described above, then the oxidation resistance is high, and / or the electrode catalyst in which the catalytic metal is supported with high dispersibility can be obtained.

[0047] The D / G ratio and the G-band FWHM can be determined, for example, using the following procedure. A Raman spectrum of the carbon support contained in the electrode catalyst for a fuel cell is measured using a Raman spectrometer. A peak is observed in the resulting Raman spectrum, located in a range of 1300 cm⁻¹. -1 up to 1400 cm -1is observed as a D-band peak, and a peak that is located in a range of 1500 cm -1 up to 1600 cm -1 The observed event is identified as a G-band peak. From the identified D-band peak and G-band peak, a G-band FWHM and a D / G ratio are determined.

[0048] The carbon support material included in the electrode catalyst for a fuel cell according to the embodiment has at least pores with an average radius of 1.0 nm to 2.5 nm. The average radius of the pores is preferably in the range of 1.7 nm to 1.9 nm. In a process for producing the electrode catalyst for a fuel cell according to the embodiment described below, an oxidation step of a carbon support material is carried out to form, in addition to the pores initially present in the carbon support material, fine pores with a radius in the range described above. The pores present on the surface of the carbon support can function as carrier sites for the catalytic metal.Accordingly, in the embodiment, the carbon support included in the electrode catalyst for a fuel cell has at least pores with a radius in the area described above; consequently, the electrode catalyst can be obtained in which the catalytic metal is supported with high dispersibility.

[0049] The average radius of the pores is not subject to any particular restrictions, but can be determined, for example, by measuring the pore distribution of the carbon support contained in the electrode catalyst for a fuel cell using a pore distribution measuring device.

[0050] The catalytic metal included in the electrode catalyst for a fuel cell according to the embodiment has a crystallite size of the (220) plane of platinum in the range of 4.5 nm or less. The crystallite size of the (220) plane of platinum is preferably equal to or greater than 3.2 nm and less than 4.1 nm, and more preferably equal to or greater than 3.3 nm and less than 4.1 nm. If the catalytic metal included in the electrode catalyst for a fuel cell has a crystallite size of the (220) plane of platinum in the range of 4.5 nm or less, in particular less than 4.1 nm, the electrode catalyst can be obtained in which the catalytic metal is supported with high dispersibility.Furthermore, if the catalytic metal included in the electrode catalyst for a fuel cell has a crystallite size of the (220) plane of platinum in a range of 3.2 nm or more, in particular 3.3 nm or more, the electrode catalyst can be obtained with high oxidation resistance.

[0051] In general, the crystallite size of platinum in the (220) plane of the catalytic metal contained in the electrode catalyst for a fuel cell can vary depending on the following factors: The smaller the specific surface area of ​​the carbon support in the electrode catalyst, the larger the crystallite size of platinum in the (220) plane. The greater the amount of platinum in the electrode catalyst, the larger the crystallite size of platinum in the (220) plane. Furthermore, the higher the heat treatment temperature after the deposition of platinum during the manufacturing of the electrode catalyst, the larger the crystallite size of platinum in the (220) plane.As described above, the carbon support included in the electrode catalyst for a fuel cell according to the embodiment has a large crystallite size (Lc) (i.e., 5.0 nm or more) of the (002) plane of carbon. In general, a carbon support with a high Lc has a small specific surface area. In the embodiment, the specific surface area can be increased to a predetermined high value due to the oxidation step described below. Next, in order to adjust the crystallite size of the (220) plane of platinum to be within the range described above, the amount of platinum support and the heat treatment temperature are adjusted in a catalytic metal application step described below so that they are within predetermined ranges, taking into account the variation factors described above.Specific conditions for obtaining the catalytic metal, which has a crystallite size corresponding to the (220) plane of platinum in the range described above, can be determined by first conducting a preliminary experiment to establish relationships between the respective conditions and then applying these relationships. In this way, the catalytic metal with a crystallite size corresponding to the (220) plane of platinum in the range described above can be obtained.

[0052] The crystallite size of the (220) plane of platinum can be determined, for example, using the following procedure. An X-ray diffractometer (XRD) is used to measure the XRD spectrum of the catalytic metal contained in the electrode catalyst for a fuel cell. Based on the obtained XRD spectrum, the crystallite size of the (220) plane of platinum is determined using the Scherrer equation. Furthermore, there is a certain relationship between the crystallite size of the (220) plane of platinum and the crystallite sizes of other lattice planes of platinum, such as the (111) plane. Accordingly, the crystallite size of the (220) plane of platinum can be calculated based on the crystallite sizes of other lattice planes of platinum, such as the (111) plane.

[0053] It is preferred that the catalytic metal included in the electrode catalyst for a fuel cell according to the embodiment is platinum. In this case, the electrode catalyst for a fuel cell has a CO adsorption capacity that is usually in the range of 24 ml / g Pt or more, and typically from 24 ml / g Pt to 35 ml / g Pt. Alternatively, it is preferred that the catalytic metal included in the electrode catalyst for a fuel cell is a platinum alloy containing platinum and one or more additional metallic elements. Examples of the one or more additional metallic elements forming a platinum alloy with platinum in this case are, among others, cobalt (Co), gold (Au), palladium (Pd), nickel (Ni), manganese (Mn), iridium (Ir), iron (Fe), copper (Cu), titanium (Ti), tantalum (Ta), niobium (Nb), yttrium (Y), and lanthanide elements such as gadolinium (Gd), lanthanum (La), and cerium (Ce).The one or more additional metallic elements preferably used are cobalt (Co), gold (Au), palladium (Pd), nickel (Ni), manganese (Mn), copper (Cu), titanium (Ti), tantalum (Ta), or niobium (Nb). In the platinum alloy, the atomic ratio of platinum to the one or more additional metallic elements is preferably in the range of 10:1 to 1:2. In this case, the electrode catalyst for a fuel cell according to the embodiment typically has a CO adsorption capacity in the range of 18 ml / g Pt or more, typically 24 ml / g Pt or more, and particularly 24 ml / g Pt to 35 ml / g Pt. In the electrode catalyst whose CO adsorption capacity is in the range described above, the catalytic metal is carried on the carbon support with high dispersibility.Accordingly, if the electrode catalyst for a fuel cell has a CO adsorption quantity in the range described above, the electrode catalyst can be obtained in which the catalytic metal is carried with high dispersibility.

[0054] It is preferred that the electrode catalyst for a fuel cell according to the embodiment contains the catalytic metal, which has the properties described above, in a carrier quantity of 2 wt% to 40 wt% based on the total mass of the electrode catalyst. It is further preferred that the electrode catalyst for a fuel cell contains the catalytic metal, which has the properties described above, in a carrier quantity of 15 wt% to 35 wt% based on the total mass of the electrode catalyst. Alternatively, it is preferred that the electrode catalyst for a fuel cell contains the catalytic metal, which has the properties described above, in a carrier quantity that is greater than or equal to 4.5 wt% and less than 15 wt% based on the total mass of the electrode catalyst.If the electrode catalyst for a fuel cell contains the catalytic metal in a carrier quantity of 15 wt% to 35 wt%, it can be used as a cathode. If the electrode catalyst contains the catalytic metal in a carrier quantity greater than or equal to 4.5 wt% and less than 15 wt%, it can be used as an anode.

[0055] The amount of carrier of the catalytic metal can be determined by dissolving the catalytic metal contained in the electrode catalyst, for example in aqua regia, and determining the amount of ions of the catalytic metal in the solution using an inductively coupled plasma (ICP) emission spectrometer.

[0056] In the electrode catalyst for a fuel cell according to the embodiment, it is particularly preferred that the crystallite size (Lc) of the (002) plane of carbon and the specific surface area of ​​the carbon support lie within the ranges described above, and that the crystallite size of the (220) plane of platinum of the catalytic metal lies within the range described above. In this case, depending on the type of catalytic metal, the electrode catalyst for a fuel cell exhibits a CO adsorption capacity within the range described above and usually maintains the ECSA in a range of 60% or more, typically 65% ​​or more, and particularly 75% or more. Maintaining the ECSA in the range described above is higher than maintaining the ECSA of an electrode catalyst for a fuel cell of the prior art.If the electrode catalyst for a fuel cell according to the embodiment has a CO adsorption quantity and a maintenance of the ECSA in the ranges described above, the electrode catalyst can accordingly be obtained in which the catalytic metal is carried with high dispersibility and which has high oxidation resistance. 2. Fuel cell

[0057] As described above, the electrode catalyst for a fuel cell according to the embodiment can be used either as the cathode or as the anode of a fuel cell.

[0058] In the electrode catalyst for a fuel cell according to the embodiment, the catalytic metal is carried with high dispersibility and / or high oxidation resistance. Accordingly, a fuel cell comprising a cathode and / or an anode, which includes the electrode catalyst for a fuel cell according to the embodiment, has a high power generation capacity and can exhibit high durability even after long-term use. By using such a fuel cell in an automobile or the like, consistently high performance can be achieved even after long-term use. 3. Method for producing an electrode catalyst for a fuel cell

[0059] A method for producing an electrode catalyst for a fuel cell according to the embodiment is described below. 3-1. Oxidation step

[0060] The method for producing the electrode catalyst for a fuel cell according to the embodiment includes an oxidation step of oxidizing a carbon support material by thermal oxidation of the carbon support material in the presence of oxygen or by treating the carbon support material with an oxidizing agent such that a carbon support is obtained which has a crystallite size (Lc) of the (002) plane of carbon in a range of 5.0 nm or more, at least pores with an average radius of 1.0 nm to 2.5 nm, and a specific surface area in a range of 95 m². 2 / g up to 170 m 2 / g

[0061] In a process for manufacturing an electrode catalyst for a fuel cell, a common step involves performing a heat treatment on a carbon support material in the presence of an inert gas. This step aims to develop a graphite structure on the surface of the carbon support material to improve its crystallinity. The improved crystallinity of the carbon support material enhances the oxidation resistance of the resulting electrode catalyst. However, this improved crystallinity can also decrease the specific surface area of ​​the carbon support material.Therefore, while heat treatment of the carbon support material in an inert gas atmosphere can contribute to improving the oxidation resistance of an electrode catalyst obtained as a product, it can reduce the degree of dispersion of the catalytic metal introduced into the electrode catalyst.

[0062] The present inventors have discovered that by oxidizing a carbon support material under predetermined conditions, the specific surface area of ​​the surface of a carbon support obtained as a product can be increased to a predetermined range, and the crystallinity and abundance ratio of a graphite structure can be maintained within a predetermined range. Accordingly, by carrying out this step, the dispersibility of the catalytic metal incorporated into an electrode catalyst obtained as a product can be improved, as can its oxidation resistance.

[0063] The carbon support material used in this step is not subject to any special restrictions, provided it is commonly used in the technical field. It is preferred that the support material has a crystallite size (Lc) of the (002) plane of carbon in the range of 5.0 nm or more and an Lc in the range of 5.0 nm to 9.0 nm. Furthermore, it is preferred that the support material has a specific surface area in the range of 80 m². 2 / g or less and a specific surface area over a range of 20 m 2 / g up to 80 m 2 / g. TOCA BLACK #3855 (trade name, manufactured by Tokai Carbon Co., Ltd.), TOCA BLACK #3845 (trade name, manufactured by Tokai Carbon Co., Ltd.), or TOCA BLACK #3800 (trade name, manufactured by Tokai Carbon Co., Ltd.) is particularly preferred as the carbon support material. By using the carbon support material whose Lc and specific surface area are within the ranges described above, a carbon support with the properties described above can be obtained.

[0064] In this step, if the carbon support material is oxidized by thermal oxidation in the presence of oxygen, the temperature of the thermal oxidation is necessarily in the range of 580°C to 650°C. The temperature of the thermal oxidation is preferably in the range of 590°C to 630°C. The duration of the thermal oxidation at the specified temperature is preferably in the range of 2 to 8 hours and even more preferably in the range of 3 to 7 hours. The thermal oxidation is preferably carried out in the presence of an oxygen-containing gas and even more preferably in the presence of air. By carrying out this step under the conditions described above, a carbon support can be obtained that exhibits the properties described above.

[0065] If, in this step, the carbon support material is oxidized by treating the carbon support material with an oxidizing agent, the oxidizing agent preferably contains potassium permanganate, sulfuric acid, nitric acid or hydrogen peroxide, and more preferably the oxidizing agent contains potassium permanganate.

[0066] The amount of oxidizing agent is preferably in the range of 2.5 mol% to 14.5 mol%, more preferably in the range of 2.5 mol% to 7.5 mol%, and even more preferably in the range of 4.0 mol% to 7.5 mol%, based on the total number of carbon atoms in the carbon support material. If the oxidizing agent is used at a concentration of 14.5 mol% or less, the D / G ratio of the carbon support obtained as a product can be adjusted to lie within the range described above. That is, the crystallinity and abundance ratio of a graphite structure in the carbon support can be maintained within desired ranges. Furthermore, if the oxidizing agent is used at a concentration of 2.5 mol% or more, the oxidation reaction of the carbon support material can be carried out under controlled conditions.Consequently, a carbon carrier can be obtained that exhibits the properties described above.

[0067] The oxidizing agent used in this step may, in addition to the components described above, further comprise one or more auxiliary components selected from the group consisting of sulfuric acid, potassium nitrate, hydrogen peroxide and water, and sodium nitrate. The auxiliary components are preferably a combination of one or more components selected from the group consisting of sulfuric acid, potassium nitrate, and hydrogen peroxide and water, and more preferably a combination of sulfuric acid and hydrogen peroxide and water, or a combination of sulfuric acid, potassium nitrate, and hydrogen peroxide and water. Because the oxidizing agent used in this step further comprises the auxiliary components described above, the oxidation reaction of the carbon support material can be carried out in a controlled manner. Consequently, a carbon support exhibiting the properties described above can be obtained.

[0068] If, in this step, the carbon support material is oxidized by treating it with an oxidizing agent, an excess of oxygen may remain in the carbon support. If the carbon support contains an excess of oxygen, in a subsequent step of applying the catalytic metal, carbon in the carbon support near the catalytic metal may be further oxidized due to the action of the catalytic metal. In this case, the amount of catalytic metal introduced into the carbon support may decrease or be removed. Therefore, the movement and / or aggregation of the catalytic metal may be accelerated.Accordingly, in this step, if the carbon support material is oxidized by treating it with an oxidizing agent, it is preferred that the step further includes a heat treatment of the carbon support material treated with the oxidizing agent in the presence of an inert gas. In this case, the heat treatment temperature is preferably in the range of 600°C to 1000°C and more preferably in the range of 700°C to 900°C. The duration of the heat treatment at the heat treatment temperature is preferably in the range of 1 hour to 6 hours and more preferably in the range of 1 hour to 3 hours. The inert gas is preferably argon, nitrogen, or helium, and more preferably argon.By carrying out heat treatment on the carbon support material treated with the oxidizing agent under the conditions described above, the movement and / or aggregation of the catalytic metal caused by an excess amount of residual oxygen can be substantially prevented.

[0069] It is preferred that the carbon support obtained in this step has a crystallite size (Lc) of the (002) plane of carbon, a specific surface area, a D / G ratio and a G-band FWHM which lie in the ranges described above.

[0070] The carbon support obtained in this step usually contains oxygen at an oxygen concentration of 0.6 wt% or more, and typically from 0.7 wt% to 2.8 wt% based on the total mass of the carbon support. If the oxygen concentration is 0.6 wt% or more, the number of support sites for the catalytic metal can be adequately ensured. Furthermore, if the oxygen concentration is 2.8 wt% or less, movement and / or aggregation of the catalytic metal caused by excess residual oxygen can be substantially prevented. The oxygen concentration can be determined, for example, using a pulsed heating and melting NDIR method in an inert gas.

[0071] This step results in the formation of fine pores in addition to the pores initially present in the carbon support material. Therefore, the carbon support obtained in this step exhibits, besides the pores initially present in the carbon support material, at least pores with a radius in the range of 1.0 nm to 2.5 nm, and typically from 1.7 nm to 1.9 nm. The pores present on the surface of the carbon support can function as carriers for the catalytic metal. Accordingly, the carbon support included in the electrode catalyst for a fuel cell according to the embodiment has additional pores with a radius in the range described above; consequently, the electrode catalyst can be obtained in which the catalytic metal is supported with high dispersibility.The average radius of the pores present in the carbon support material or the carbon support can be determined using the method described above. 3-2. Step of applying the catalytic metal

[0072] The method for producing the electrode catalyst for a fuel cell according to the embodiment includes a step of applying the catalytic metal by causing the carbon support obtained in the oxidation step and a catalytic metal material selected from platinum and a platinum alloy to react with each other in such a way that catalytic metal is applied to the carbon support.

[0073] It is preferred that the catalytic metal material used in this step comprises a platinum-containing complex, such as dinitrodiamine platinum(II) nitrate, or a hexahydroxoplatinum-amine complex. Furthermore, if the catalytic metal included in the electrode catalyst for a fuel cell produced by the process according to the embodiment is a platinum alloy, it is preferred that, in addition to the compounds described above, the catalytic metal material also comprises one or more additional metallic elements such as cobalt nitrate, nickel nitrate, or manganese nitrate, so that it forms a platinum alloy with platinum.

[0074] This process can be carried out by using a method commonly used in the technical field, such as a colloid process or a precipitation-deposition process.

[0075] It is preferred that this step further includes a step of carrying out a heat treatment on a product obtained by inducing the reaction of the carbon support obtained in the oxidation step and a catalytic metal material selected from platinum and a platinum alloy, in the presence of an inert gas. In this case, the heat treatment temperature is preferably in the range of 600°C to 1000°C and more preferably in the range of 700°C to 900°C. The duration of the heat treatment at the heat treatment temperature is preferably in the range of 1 hour to 6 hours and more preferably in the range of 1 hour to 3 hours. The inert gas is preferably argon, nitrogen, or helium, and more preferably argon.By carrying out a heat treatment under the conditions described above on a product obtained by causing the carbon support obtained in the oxidation step and a catalytic metal material selected from platinum and a platinum alloy to react together, an electrode catalyst can be obtained in which the catalytic metal exhibiting the desired properties is supported.

[0076] As described above, in the process for producing the electrode catalyst for a fuel cell according to the embodiment, the carbon support material is oxidized under predetermined conditions. Consequently, pores are formed on the surface of the carbon support material, and thus the specific surface area can be improved to a predetermined range. The pores can act as support sites for the catalytic metal. Accordingly, the process for producing the electrode catalyst for a fuel cell according to the embodiment can yield an electrode catalyst for a fuel cell that exhibits the properties described above, including both high bulk activity and high stability.

[0077] The invention is described in more detail below using examples. However, the technical scope of the invention is not limited to these examples. I. Preparation of the electrode catalyst I-1. Platinum electrode catalyst for one cathode Example 1-1-1

[0078] 20 g of a carbon support material (TOCA BLACK; #3855; manufactured by Tokai Carbon Co., Ltd.) were added to 350 g of sulfuric acid, followed by stirring. Next, 10.8 g (4.1 mol% based on the total number of carbon atoms in the carbon support material) of potassium permanganate were added, followed by stirring for 3 days and nights. Next, 800 g of ion-exchanged water were added, and then 6 mL of a 30% hydrogen peroxide solution were added. This mixture was stirred for 1 day and 1 night, filtered, and washed. The washed product was filtered, and the solids were added to 500 mL of a 1N nitric acid solution, followed by stirring for 1 day and 1 night. The reaction product was filtered and washed. The washed product was dried at 80°C for 15 hours and subjected to heat treatment in argon gas at 700°C (conditions: heating by 5°C / min).and a two-hour holding at 700°C) to obtain a carbon support (oxidation step). 420 g of an aqueous 0.1 N nitric acid solution were added to 10 g of the carbon support and dispersed therein. A dinitrodiamineplatinum(II) nitrate solution and 50 g of 99.5% ethanol were successively added to this dispersion, the dinitrodiamineplatinum(II) nitrate solution containing 4.29 g of Pt, resulting in a Pt support content of 30 wt% based on the total mass of the final product. This mixture was stirred sufficiently to achieve substantial homogeneity and heated from 60°C to 90°C for 3 hours. Upon completion of the heating, the resulting dispersion was repeatedly filtered and washed until the conductivity of the filtrate was 5 µS / cm or less. The resulting solids were dried for 15 hours by blowing air through them at 80°C. The dried powder was then subjected to heat treatment in argon gas at 700°C (conditions: heating by 5°C / min).and two hours of holding at 700°C) (step of applying the catalytic metal). A powder of an electrode catalyst was obtained using the above-described method. Example 1-1-2

[0079] 20 g of a carbon support material (TOCA BLACK; #3855; manufactured by Tokai Carbon Co., Ltd.) were added to 350 g of sulfuric acid, followed by stirring. Next, 18 g (6.8 mol% based on the total number of carbon atoms in the carbon support material) of potassium permanganate were added, followed by stirring for 3 days and nights. Next, 800 g of ion-exchanged water were added, and then 10 mL of a 30% hydrogen peroxide solution were added. This mixture was stirred for 1 day and 1 night, filtered, and washed. The washed product was filtered, and the solids were added to 500 mL of a 1N nitric acid solution, followed by stirring for 1 day and 1 night. The reaction product was filtered and washed. The washed product was dried at 80°C for 15 hours and subjected to heat treatment in argon gas at 700°C (conditions: heating by 5°C / min).and a two-hour holding at 700°C) to obtain a carbon support (oxidation step). 420 g of an aqueous 0.1 N nitric acid solution were added to 10 g of the carbon support and dispersed therein. A dinitrodiamineplatinum(II) nitrate solution and 50 g of 99.5% ethanol were successively added to this dispersion, the dinitrodiamineplatinum(II) nitrate solution containing 4.29 g of Pt, resulting in a Pt support content of 30 wt% based on the total mass of the final product. This mixture was stirred sufficiently to achieve substantial homogeneity and heated from 60°C to 90°C for 3 hours. Upon completion of the heating, the resulting dispersion was repeatedly filtered and washed until the conductivity of the filtrate was 5 µS / cm or less. The resulting solids were dried for 15 hours by blowing air through them at 80°C. The dried powder was then subjected to heat treatment in argon gas at 700°C (conditions: heating by 5°C / min).and two hours of holding at 700°C) (step of applying the catalytic metal). A powder of an electrode catalyst was obtained using the above-described method. Example 1-1-3

[0080] 20 g of a carbon support material (TOCA BLACK; #3855; manufactured by Tokai Carbon Co., Ltd.) were added to 350 g of sulfuric acid, followed by stirring. Next, 1.92 g of sodium nitrate and 18 g (2.7 mol% based on the total number of carbon atoms in the carbon support material) of potassium permanganate were added, followed by stirring for 3 days and nights. Next, 800 g of ion-exchanged water were added, and then 4 mL of a 30% hydrogen peroxide solution were added. This mixture was stirred for 1 day and 1 night, filtered, and washed. The washed product was filtered, and the solids were added to 500 mL of a 1N nitric acid solution, followed by stirring for 1 day and 1 night. The reaction product was filtered and washed. The washed product was dried at 80°C for 15 hours and subjected to heat treatment in argon gas at 700°C (conditions: heating by 5°C / min).and a two-hour holding at 700°C) to obtain a carbon support (oxidation step). 420 g of an aqueous 0.1 N nitric acid solution were added to 10 g of the carbon support and dispersed therein. A dinitrodiamineplatinum(II) nitrate solution and 50 g of 99.5% ethanol were successively added to this dispersion, the dinitrodiamineplatinum(II) nitrate solution containing 2.5 g of Pt, resulting in a Pt support content of 20 wt% based on the total mass of the final product. This mixture was stirred sufficiently to achieve substantial homogeneity and heated from 60°C to 90°C for 3 hours. Upon completion of the heating, the resulting dispersion was repeatedly filtered and washed until the conductivity of the filtrate was 5 µS / cm or less. The resulting solids were dried for 15 hours by blowing air through them at 80°C. The dried powder was then subjected to heat treatment in argon gas at 700°C (conditions: heating by 5°C / min).and two hours of holding at 700°C) (step of applying the catalytic metal). A powder of an electrode catalyst was obtained using the above-described method. Example 1-1-4

[0081] An electrode catalyst was produced using the same procedure as in Example 1-1-3, except that in the oxidation step the temperature of the heat treatment in argon gas was changed to 800°C. Example 1-1-5

[0082] An electrode catalyst was produced using the same procedure as in Example 1-1-3, except that in the oxidation step the temperature of the heat treatment in argon gas was changed to 900°C. Example 1-1-6

[0083] An electrode catalyst was produced using the same procedure as in Example 1-1-3, except that in the step of applying the catalytic metal the temperature of the heat treatment in argon gas was changed to 800°C. Example 1-1-7

[0084] An electrode catalyst was prepared in the same procedure as in Example 1-1-3, except that in the oxidation step the amount of sodium nitrate added was changed to 2.88 g, the amount of potassium permanganate added was changed to 10.8 g (4.1 mol-% based on the total number of carbon atoms of the carbon support material), and the amount of 30% hydrogen peroxide water added was changed to 6 ml. Example 1-1-8

[0085] An electrode catalyst was prepared using the same procedure as in Example 1-1-3, except that in the oxidation step the amount of sodium nitrate added was changed to 2.88 g, the amount of potassium permanganate added was changed to 10.8 g (4.1 mol% based on the total number of carbon atoms of the carbon support material), and the amount of 30% hydrogen peroxide water added was changed to 6 ml; and in the application of the catalytic metal step, the temperature of the heat treatment in argon gas was changed to 800°C. Example 1-1-9

[0086] An electrode catalyst was prepared in the same procedure as in Example 1-1-1, except that in the step of applying the catalytic metal the amount of dinitrodiamine platinum(II) nitrate solution added was changed to an amount containing 2.5 g Pt, so that a Pt carrier amount was 20 wt% based on the total mass of a final product. Example 1-1-10

[0087] An electrode catalyst was prepared in the same procedure as in Example 1-1-1, except that in the oxidation step the amount of potassium permanganate added was changed to 18 g (6.8 mol% based on the total number of carbon atoms of the carbon support material) and the amount of 30% hydrogen peroxide water added was changed to 10 ml; and in the application of the catalytic metal step the amount of dinitrodiamineplatinum(II) nitrate solution added was changed to an amount containing 2.5 g Pt, so that a Pt support amount was 20 wt% based on the total mass of a final product. Example 1-1-11

[0088] 25 g of a carbon support material (TOCA BLACK; #3855; manufactured by Tokai Carbon Co., Ltd.) were weighed into a magnetic dish. This carbon support material was subjected to thermal oxidation in air at 590°C (conditions: two-hour heating and five-hour holding at 590°C) to obtain a carbon support (oxidation step). 420 g of an aqueous 0.1 N nitric acid solution were added to 10 g of the carbon support and dispersed therein. A dinitrodiamineplatinum(II) nitrate solution and 50 g of 99.5% ethanol were successively added to this dispersion, the dinitrodiamineplatinum(II) nitrate solution containing 2.5 g of Pt, resulting in a Pt support content of 20 wt% based on the total mass of the final product. This mixture was stirred sufficiently to be essentially homogeneous and heated at 60°C to 90°C for 3 hours.After heating, the resulting dispersion was repeatedly filtered and washed until the conductivity of the filtrate was 5 µS / cm or less. The resulting solids were dried by blowing air through them for 15 hours at 80°C. The dried powder was then subjected to heat treatment in argon gas at 800°C (conditions: heating at 5°C / min and holding at 800°C for two hours) (step of catalytic metal application). A powder of an electrode catalyst was obtained by the above-described procedure. Example 1-1-12

[0089] An electrode catalyst was produced using the same procedure as in Example 1-1-11, except that in the oxidation step the temperature of the thermal oxidation in air was changed to 600°C. Example 1-1-13

[0090] An electrode catalyst was produced using the same procedure as in Example 1-1-11, except that in the oxidation step the temperature of the thermal oxidation in air was changed to 600°C and in the step of applying the catalytic metal the temperature of the heat treatment in argon gas was changed to 700°C. Example 1-1-14

[0091] An electrode catalyst was produced using the same procedure as in Example 1-1-11, except that in the oxidation step the temperature of the thermal oxidation in air was changed to 610°C and in the step of applying the catalytic metal the temperature of the heat treatment in argon gas was changed to 700°C. Example 1-1-15

[0092] An electrode catalyst was produced using the same procedure as in Example 1-1-11, except that in the oxidation step the temperature of the thermal oxidation in air was changed to 620°C and in the step of applying the catalytic metal the temperature of the heat treatment in argon gas was changed to 700°C. Example 1-1-16

[0093] An electrode catalyst was produced using the same procedure as in Example 1-1-11, except that in the oxidation step the temperature of the thermal oxidation in air was changed to 630°C and in the step of applying the catalytic metal the temperature of the heat treatment in argon gas was changed to 700°C. Comparative example 1-1-1

[0094] 420 g of an aqueous 0.1 N nitric acid solution were added to and dispersed in 10 g of a carbon support (TOCA BLACK; #3855; manufactured by Tokai Carbon Co., Ltd.). A dinitrodiamineplatinum(II) nitrate solution and 50 g of 99.5% ethanol were successively added to this dispersion, the dinitrodiamineplatinum(II) nitrate solution containing 4.29 g of Pt, resulting in a Pt support content of 30 wt% based on the total mass of the final product. This mixture was stirred sufficiently to achieve substantial homogeneity and heated from 60°C to 90°C for 3 hours. Upon completion of heating, the resulting dispersion was repeatedly filtered and washed until the conductivity of the filtrate was 5 µS / cm or less. The resulting solids were dried for 15 hours by blowing air through them at 80°C. The dried powder was then subjected to heat treatment in argon gas at 700°C (conditions: heating by 5°C / min).and two hours of holding at 700°C) (step of applying the catalytic metal). A powder of an electrode catalyst was obtained using the above-described method. Comparison example 1-1-2

[0095] An electrode catalyst was produced using the same procedure as in Comparative Example 1-1-1, except that in the step of applying the catalytic metal the temperature of the heat treatment in argon gas was changed to 800°C. Comparative example 1-1-3

[0096] An electrode catalyst was produced using the same procedure as in Comparative Example 1-1-1, except that in the step of applying the catalytic metal the temperature of the heat treatment in argon gas was changed to 900°C. Comparative example 1-1-4

[0097] A carbon support material (Ketjen; ​​manufactured by Lion Corporation) was subjected to heat treatment in argon gas at 2800°C (conditions: heating at 5°C / min and holding at 2800°C for two hours) to obtain a carbon support. 420 g of an aqueous 0.1 N nitric acid solution were added to 10 g of the carbon support and dispersed therein. A dinitrodiamineplatinum(II) nitrate solution and 50 g of 99.5% ethanol were successively added to this dispersion, the dinitrodiamineplatinum(II) nitrate solution containing 4.29 g of platinum, resulting in a platinum support content of 30 wt% based on the total mass of the final product. This mixture was stirred sufficiently to achieve substantial homogeneity and heated to 90°C at 60°C for 3 hours. After heating was complete, the resulting dispersion was repeatedly filtered and washed until the conductivity of the filtrate was 5 µS / cm or less.The resulting solids were dried for 15 hours by blowing air at 80°C. The dried powder was then subjected to heat treatment in argon gas at 700°C (conditions: heating at 5°C / min and holding at 700°C for two hours) (step of applying the catalytic metal). A powder of an electrode catalyst was obtained using the above-described method. Comparison example 1-1-5

[0098] An electrode catalyst was produced using the same procedure as in Comparative Example 1-1-4, except that in the step of applying the catalytic metal the temperature of the heat treatment in argon gas was changed to 700°C. Comparative example 1-1-6

[0099] An electrode catalyst was prepared using the same procedure as in Comparative Example 1-1-1, except that the carbon support material was changed to Ketjen (manufactured by Lion Corporation); and in the step of applying the catalytic metal, the temperature of the heat treatment in argon gas was changed to 800°C. Comparative example 1-1-7

[0100] An electrode catalyst was prepared using the same procedure as in Comparative Example 1-1-1, except that the carbon support material was changed to Ketjen (manufactured by Lion Corporation); and in the step of applying the catalytic metal, the temperature of the heat treatment in argon gas was changed to 900°C. Comparative example 1-1-8

[0101] An electrode catalyst was prepared in the same procedure as in Comparative Example 1-1-1, except that in the step of applying the catalytic metal the amount of dinitrodiamine platinum(II) nitrate solution added was changed to an amount containing 2.5 g Pt, so that a Pt carrier amount was 20 wt% based on the total mass of an end product. Comparative example 1-1-9

[0102] An electrode catalyst was prepared in the same procedure as in Comparative Example 1-1-1, except that in the step of applying the catalytic metal, the amount of dinitrodiamine platinum(II) nitrate solution added was changed to an amount containing 2.5 g Pt, so that a Pt carrier amount was 20 wt% based on the total mass of an end product; and in the step of applying the catalytic metal, the temperature of the heat treatment in argon gas was changed to 900°C. Comparative example 1-1-10

[0103] 25 g of a carbon support material (TOCA BLACK; #3855; manufactured by Tokai Carbon Co., Ltd.) were weighed into a magnetic dish. This carbon support material was subjected to thermal oxidation in air at 550°C (conditions: two-hour heating and five-hour holding at 550°C) to obtain a carbon support (oxidation step). 420 g of an aqueous 0.1 N nitric acid solution were added to 10 g of the carbon support and dispersed therein. A dinitrodiamineplatinum(II) nitrate solution and 50 g of 99.5% ethanol were successively added to this dispersion, the dinitrodiamineplatinum(II) nitrate solution containing 2.5 g of Pt, resulting in a Pt support content of 20 wt% based on the total mass of the final product. This mixture was stirred sufficiently to be essentially homogeneous and heated at 60°C to 90°C for 3 hours.After heating, the resulting dispersion was repeatedly filtered and washed until the conductivity of the filtrate was 5 µS / cm or less. The resulting solids were dried for 15 hours by blowing air through them at 80°C. The dried powder was then subjected to heat treatment in argon gas at 800°C (conditions: heating at 5°C / min and holding at 800°C for two hours) (step of catalytic metal deposition). A powder of an electrode catalyst was obtained by the above-described procedure. Comparative example 1-1-11

[0104] An electrode catalyst was produced using the same procedure as in Comparative Example 1-1-10, except that in the oxidation step the temperature of the thermal oxidation in air was changed to 560°C. Comparative example 1-1-12

[0105] An electrode catalyst was produced using the same procedure as in Comparative Example 1-1-10, except that in the oxidation step the temperature of the thermal oxidation in air was changed to 570°C. I-2. Platinum alloy electrode catalyst for one cathode. Example 1-2-1

[0106] 20 g of a carbon support material (TOCA BLACK; #3855; manufactured by Tokai Carbon Co., Ltd.) were added to 350 g of sulfuric acid, followed by stirring. Next, 2.88 g of sodium nitrate and 10.8 g (4.1 mol% based on the total number of carbon atoms in the carbon support material) of potassium permanganate were added, followed by stirring for 3 days and nights. Next, 800 g of ion-exchanged water were added, and then 6 mL of a 30% hydrogen peroxide solution were added. This mixture was stirred for 1 day and 1 night, filtered, and washed. The washed product was filtered, and the solids were added to 500 mL of a 1N nitric acid solution, followed by stirring for 1 day and 1 night. The reaction product was filtered and washed. The washed product was dried at 80°C for 15 hours and subjected to heat treatment in argon gas at 800°C (conditions: heating by 5°C / min).and a two-hour holding at 800°C) to obtain a carbon support (oxidation step). 420 g of an aqueous 0.1 N nitric acid solution were added to 10 g of the carbon support and dispersed therein. A dinitrodiamineplatinum(II) nitrate solution and 50 g of 99.5% ethanol were successively added to this dispersion, the dinitrodiamineplatinum(II) nitrate solution containing 4.29 g of Pt, resulting in a Pt support content of 30 wt% based on the total mass of the final product. This mixture was stirred sufficiently to achieve substantial homogeneity and heated from 60°C to 90°C for 3 hours. Upon completion of the heating, the resulting dispersion was repeatedly filtered and washed until the conductivity of the filtrate was 5 µS / cm or less. The resulting solids were dried for 15 hours by blowing air through them at 80°C. The dried powder was then subjected to heat treatment in argon gas at 800°C (conditions: heating by 5°C / min).and held at 800°C for two hours). 30 wt% of the resulting platinum-supported carbon support was dispersed in pure water containing 80 times the total mass of the carbon support. An aqueous cobalt nitrate solution, obtained by dissolving a commercially available cobalt nitrate hexahydrate in pure water, was added dropwise to the dispersion in such a quantity as to achieve a platinum-to-cobalt molar ratio (Pt:Co) of 2:1. After completion of the dropwise addition, 1 molar equivalent to 6 molar equivalents of an aqueous sodium borohydride solution, based on the cobalt content of the cobalt nitrate used, was added dropwise. After completion of the dropwise addition, the reaction mixture was stirred for 1 to 20 hours. Next, the reaction mixture was repeatedly filtered and washed until the conductivity of the filtrate was 5 µS / cm or less.The resulting powder cake was dried for 15 hours by blowing air through it at 80°C. The dried powder was then subjected to a heat treatment in argon gas at 800°C (conditions: heating at 5°C / min and holding at 800°C for two hours) to form a platinum-cobalt alloy (the step of applying the catalytic metal). An electrode catalyst powder was obtained using the above-described method. Example 1-2-2

[0107] An electrode catalyst was produced in the same process as in Example 1-2-1, except that in the oxidation step the temperature of the thermal oxidation in argon gas was changed to 700°C; and in the step of applying the catalytic metal the temperature of the heat treatment in argon gas after the application of platinum was changed to 700°C and the temperature of the heat treatment in argon gas after the application of cobalt was changed to 700°C. Example 1-2-3

[0108] An electrode catalyst was produced in the same process as in Example 1-2-1, except that no sodium nitrate was added in the oxidation step; the temperature of the thermal oxidation in argon gas was changed to 700°C in the oxidation step; and the temperature of the heat treatment in argon gas after the application of platinum was changed to 700°C in the application of the catalytic metal step, and the temperature of the heat treatment in argon gas after the application of cobalt was changed to 700°C. Example 1-2-4

[0109] An electrode catalyst was prepared using the same procedure as in Example 1-2-1, except that no sodium nitrate was added in the oxidation step; the amount of potassium permanganate added in the oxidation step was changed to 18 g (6.8 mol% based on the total number of carbon atoms of the carbon support material), the amount of 30% hydrogen peroxide water added was changed to 10 ml, and the temperature of the heat treatment in argon gas was changed to 700°C; and in the application of the catalytic metal step, the temperature of the heat treatment in argon gas was changed to 700°C after the application of platinum and after the application of cobalt. Example 1-2-5

[0110] An electrode catalyst was prepared in the same process as in Example 1-2-1, except that in the oxidation step the temperature of the heat treatment in argon gas was changed to 700°C; and in the step of applying the catalytic metal the amount of dinitrodiamine platinum(II) nitrate solution added was changed to an amount containing 2.5 g Pt, so that a Pt carrier amount was 20 wt% based on the total mass of a final product. Example 1-2-6

[0111] An electrode catalyst was prepared in the same procedure as in Example 1-2-1, except that in the step of applying the catalytic metal, the amount of dinitrodiamine platinum(II) nitrate solution added was changed to an amount containing 2.5 g of Pt, so that a Pt carrier amount was 20 wt% based on the total mass of a final product. Example 1-2-7

[0112] An electrode catalyst was prepared using the same procedure as in Example 1-2-1, except that in the oxidation step the temperature of the thermal oxidation in argon gas was changed to 700°C; and in the step of applying the catalytic metal the amount of dinitrodiamine platinum(II) nitrate solution added was changed to an amount containing 2.5 g of Pt, such that a Pt carrier amount was 20 wt% based on the total mass of an end product, the temperature of the heat treatment in argon gas after the application of platinum was changed to 700°C, and the temperature of the heat treatment in argon gas after the application of cobalt was changed to 700°C. Example 1-2-8

[0113] An electrode catalyst was prepared using the same procedure as in Example 1-2-1, except that no sodium nitrate was added in the oxidation step; the temperature of the thermal oxidation in argon gas was changed to 700°C in the oxidation step; and in the application of the catalytic metal, the amount of dinitrodiamine platinum(II) nitrate solution added was changed to an amount containing 2.5 g of Pt, such that a Pt carrier amount was 20 wt% based on the total mass of an end product; the temperature of the heat treatment in argon gas after the application of platinum was changed to 700°C; and the temperature of the heat treatment in argon gas after the application of cobalt was changed to 700°C. Example 1-2-9

[0114] An electrode catalyst was prepared using the same procedure as in Example 1-2-1, except that no sodium nitrate was added in the oxidation step; and in the oxidation step the amount of potassium permanganate added was changed to 18 g (6.8 mol-% based on the total number of carbon atoms of the carbon support material), the amount of 30% hydrogen peroxide water added was changed to 10 ml, and the temperature of the heat treatment in argon gas was changed to 700°C; and in the step of applying the catalytic metal, the added amount of dinitrodiamine platinum(II) nitrate solution was changed to an amount containing 2.5 g Pt, so that a Pt carrier amount was 20 wt% based on the total mass of an end product, the temperature of the heat treatment in argon gas after the application of platinum was changed to 700°C, and the temperature of the heat treatment in argon gas after the application of cobalt was changed to 700°C. Example 1-2-10

[0115] 25 g of a carbon support material (TOCA BLACK; #3855; manufactured by Tokai Carbon Co., Ltd.) were weighed into a magnetic dish. This carbon support material was subjected to thermal oxidation in air at 600°C (conditions: two-hour heating and five-hour holding at 600°C) to obtain a carbon support (oxidation step). 420 g of an aqueous 0.1 N nitric acid solution were added to 10 g of the carbon support and dispersed therein. A dinitrodiamineplatinum(II) nitrate solution and 50 g of 99.5% ethanol were successively added to this dispersion, the dinitrodiamineplatinum(II) nitrate solution containing 2.5 g of platinum, resulting in a platinum support content of 20 wt% based on the total mass of the final product. This mixture was stirred sufficiently to be essentially homogeneous and heated at 60°C to 90°C for 3 hours.After heating, the resulting dispersion was repeatedly filtered and washed until the conductivity of the filtrate was 5 µS / cm or less. The resulting solids were dried for 15 hours by blowing air through them at 80°C. The dried powder was then heat-treated in argon gas at 800°C (conditions: heating at 5°C / min and holding at 800°C for two hours). 20 wt% of the resulting platinum-supported carbon carrier was dispersed in pure water containing 80 times the total mass of the carbon carrier. An aqueous cobalt nitrate solution, obtained by dissolving a commercially available cobalt nitrate hexahydrate in pure water, was added dropwise to the dispersion in such a quantity that the platinum-to-cobalt molar ratio (Pt:Co) was 2:1.After completion of the dropwise addition, 1 molar equivalent of 6 molar equivalents of an aqueous sodium borohydride solution, based on the cobalt content of the cobalt nitrate used, was added dropwise. Following this dropwise addition, the reaction liquid was stirred for 1 to 20 hours. Next, the reaction mixture was repeatedly filtered and washed until the conductivity of the filtrate was 5 µS / cm or less. The resulting powder cake was dried by blowing air through it at 80°C for 15 hours. The dried powder was then subjected to a heat treatment in argon gas at 800°C (conditions: heating at 5°C / min and holding at 800°C for two hours) to form a platinum-cobalt alloy (the step of catalytic metal deposition). An electrode catalyst powder was obtained by the above-described procedure. Example 1-2-11

[0116] An electrode catalyst was produced in the same process as in Example 1-2-10, except that in the step of applying the catalytic metal, the temperature of the heat treatment in argon gas after the application of platinum was changed to 700°C and the temperature of the heat treatment in argon gas after the application of cobalt was changed to 700°C. Example 1-2-12

[0117] An electrode catalyst was produced in the same process as in Example 1-2-10, except that in the oxidation step the temperature of the thermal oxidation in air was changed to 610°C; and in the step of applying the catalytic metal the temperature of the heat treatment in argon gas after the application of platinum was changed to 700°C and the temperature of the heat treatment in argon gas after the application of cobalt was changed to 700°C. Example 1-2-13

[0118] An electrode catalyst was produced in the same process as in Example 1-2-10, except that in the oxidation step the temperature of the thermal oxidation in air was changed to 620°C; and in the step of applying the catalytic metal the temperature of the heat treatment in argon gas after the application of platinum was changed to 700°C and the temperature of the heat treatment in argon gas after the application of cobalt was changed to 700°C. Example 1-2-14

[0119] An electrode catalyst was produced in the same process as in Example 1-2-10, except that in the oxidation step the temperature of the thermal oxidation in air was changed to 630°C; and in the step of applying the catalytic metal the temperature of the heat treatment in argon gas after the application of platinum was changed to 700°C and the temperature of the heat treatment in argon gas after the application of cobalt was changed to 700°C. Comparison example 1-2-1

[0120] 420 g of an aqueous 0.1 N nitric acid solution were added to and dispersed in 10 g of a carbon support (TOCA BLACK; #3855; manufactured by Tokai Carbon Co., Ltd.). A dinitrodiamineplatinum(II) nitrate solution and 50 g of 99.5% ethanol were successively added to this dispersion, the dinitrodiamineplatinum(II) nitrate solution containing 4.29 g of Pt, resulting in a Pt support content of 30 wt% based on the total mass of the final product. This mixture was stirred sufficiently to achieve substantial homogeneity and heated from 60°C to 90°C for 3 hours. Upon completion of heating, the resulting dispersion was repeatedly filtered and washed until the conductivity of the filtrate was 5 µS / cm or less. The resulting solids were dried for 15 hours by blowing air through them at 80°C. The dried powder was then subjected to heat treatment in argon gas at 700°C (conditions: heating at 5°C / min and holding at 700°C for two hours).30 wt% of the obtained platinum-supported carbon carrier was dispersed in pure water containing 80 times the total mass of the carbon carrier. An aqueous cobalt nitrate solution, obtained by dissolving commercially available cobalt nitrate hexahydrate in pure water, was added dropwise to the dispersion in such a quantity as to achieve a platinum-to-cobalt molar ratio (Pt:Co) of 2:1. After the dropwise addition was complete, 1 molar equivalent of 6 molar equivalents of an aqueous sodium borohydride solution (based on the cobalt content of the cobalt used) was added dropwise. Following the dropwise addition, the reaction mixture was stirred for 1 to 20 hours. Next, the reaction mixture was repeatedly filtered and washed until the conductivity of the filtrate was 5 µS / cm or less. The resulting powder cake was dried by blowing air through it at 80°C for 15 hours.The dried powder was subjected to heat treatment in argon gas at 800°C (conditions: heating at 5°C / min and holding at 800°C for two hours) to form a platinum-cobalt alloy (step of catalytic metal deposition). An electrode catalyst powder was obtained using the above-described method. Comparison example 1-2-2

[0121] An electrode catalyst was produced using the same procedure as in Comparative Example 1-2-1, except that the carbon support material was changed to Ketjen (manufactured by Lion Corporation); and in the step of applying the catalytic metal, the temperature of the heat treatment in argon gas after the application of platinum was changed to 800°C. Comparison example 1-2-3

[0122] An electrode catalyst was produced using the same procedure as in Comparative Example 1-2-1, except that the carbon support material was changed to OSAB (manufactured by Denki Kagaku Kogyo KK); and in the step of applying the catalytic metal, the temperature of the heat treatment in argon gas after the application of platinum was changed to 800°C. Comparison example 1-2-4

[0123] An electrode catalyst was prepared in the same procedure as in Comparative Example 1-2-1, except that in the step of applying the catalytic metal the amount of dinitrodiamine platinum(II) nitrate solution added was changed to an amount containing 2.5 g of Pt, so that a Pt carrier amount was 20 wt% based on the total mass of an end product. Comparison example 1-2-5

[0124] An electrode catalyst was prepared in the same process as in Comparative Example 1-2-1, except that in the step of applying the catalytic metal, the amount of dinitrodiamine platinum(II) nitrate solution added was changed to an amount containing 2.5 g of Pt, such that a Pt carrier amount was 20 wt% based on the total mass of an end product; and in the step of applying the catalytic metal, the temperature of the heat treatment in argon gas after the application of platinum was changed to 900°C and the temperature of the heat treatment in argon gas after the application of cobalt was changed to 800°C. I-3. Platinum electrode catalyst for one anode. Example 2-1-1

[0125] An electrode catalyst was prepared in the same process as in Example 1-1-16, except that in the step of applying the catalytic metal, the amount of dinitrodiamine platinum(II) nitrate solution added was changed to an amount containing 0.53 g of Pt, so that a Pt carrier amount was 5 wt% based on the total mass of an end product; and in the step of applying the catalytic metal, the temperature of the heat treatment in argon gas was changed to 400°C. Example 2-1-2

[0126] An electrode catalyst was prepared in the same procedure as in Example 2-1-1, except that in the step of applying the catalytic metal the amount of dinitrodiamine platinum(II) nitrate solution added was changed to an amount containing 1.11 g of Pt, so that a Pt carrier amount was 10 wt% based on the total mass of an end product. Comparative example 2-1-1

[0127] An electrode catalyst was prepared in the same procedure as in Comparative Example 1-1-1, except that in the step of applying the catalytic metal, the amount of dinitrodiamine platinum(II) nitrate solution added was changed to an amount containing 0.53 g Pt, so that a Pt carrier amount was 5 wt% based on the total mass of an end product; and in the step of applying the catalytic metal, the temperature of the heat treatment in argon gas was changed to 400°C. Comparative example 2-1-2

[0128] An electrode catalyst was prepared in the same procedure as in Comparative Example 2-1-1, except that in the step of applying the catalytic metal the amount of dinitrodiamineplatinum(II) nitrate solution added was changed to an amount containing 1.11 g of Pt, so that a Pt carrier amount was 10 wt% based on the total mass of an end product. II. Method for evaluating the electrode catalyst II-1. Crystallite size (Lc) of the (002) plane of carbon of the carbon support

[0129] Using an X-ray diffractometer (XRD; Rint 2500; manufactured by Rigaku Corporation), an XRD spectrum of each of the carbon supports used to prepare the electrode catalysts of the examples and comparison examples was measured prior to the application of the catalytic metal. The measurement conditions were as follows: Cu tube, 50 kV, and 300 mA. Based on the obtained XRD spectrum, the crystallite size (Lc) of the (002) plane of carbon was determined using the Scherrer equation. II-2. Specific surface area of ​​the carbon support

[0130] Using a device for measuring specific surface area (BELSORP-mini; manufactured by BEL Japan, Inc.), a specific BET surface area (m 2 / g) Each of the carbon supports used to prepare the electrode catalysts of the examples and comparison examples was measured using a gas adsorption method prior to the application of the catalytic metal. The measurement conditions were as follows: Pretreatment: 150°C, two-hour vacuum degassing; and Measurement: Measurement of a nitrogen adsorption isotherm using a constant volume method. II-3. Oxygen concentration of the carbon support

[0131] Using an oxygen analyzer (model no. EMGA-920; manufactured by Horiba, Ltd.), the oxygen concentration (wt% based on the total mass of the carbon support) of each of the carbon supports used to prepare the electrode catalysts of the examples and comparison examples was measured before the application of the catalytic metal. The measurement conditions were as follows: pulse heating and melting NDIR process in an inert gas. II-4. Raman spectrum measurement of the carbon support

[0132] Using a Raman spectrometer (NRS-1000; manufactured by JASCO Corporation), a Raman spectrum of each of the carbon supports used to prepare the electrode catalysts of the examples and comparison examples was measured before the deposition of the catalytic metal. The measurement conditions were as follows: laser wavelength: 532 nm; and laser power: 100 mV. In the obtained Raman spectrum, a [missing information] was found in a range of 1300 cm⁻¹. -1 up to 1400 cm -1 The observed peak was identified as a D-band peak, and one was located in a range of 1500 cm. -1 up to 1600 cm -1 The observed peak was identified as a G-band peak. From the identified D-band peak and G-band peak, a full half-width of the G-band peak (G-band FWHM) and an intensity ratio (D / G ratio) of a D-band peak intensity I were calculated. Dto a G-band peak intensity I G certainly. II-5. Measurement of the pore distribution of the carbon support

[0133] A carbon support (TOCA BLACK; #3855; manufactured by Tokai Carbon Co., Ltd.) was thermally oxidized using the same procedure as in the oxidation step of Examples 1-1-13 to 1-1-16. Using a pore distribution measuring device (BELSORP-mini; manufactured by BEL Japan, Inc.), the pore distribution of the carbon support was measured based on a gas adsorption method before thermal oxidation, after thermal oxidation at 600°C, after thermal oxidation at 610°C, after thermal oxidation at 620°C, and after thermal oxidation at 630°C. The measurement conditions were as follows: pretreatment: 120°C, eight-hour vacuum degassing; and measurement: measurement of a nitrogen adsorption isotherm using a constant volume method. II-6. Measurement of the amount of catalytic metal carrier

[0134] A predetermined amount of the catalytic metal contained in each of the electrode catalysts of the examples and comparison examples was dissolved in aqua regia. Using an inductively coupled plasma (ICP) emission spectrometer (ICPV-8100; manufactured by Shimadzu Corporation), the amount of catalytic metal ions in the resulting solution was determined. From this amount, the amount of carrier (wt% based on the total mass of the electrode catalyst) of the catalytic metal (Pt and Co) introduced into the electrode catalyst was determined. II-7. Crystallite size of the (220) plane of platinum

[0135] Using an X-ray diffractometer (XRD; Rint 2500; manufactured by Rigaku Corporation), an XRD spectrum of each of the electrode catalysts of the examples and comparison examples was measured. The measurement conditions were as follows: Cu tube; 50 kV; and 300 mA. Based on the obtained XRD spectrum, the crystallite size of the (220) plane of platinum was determined using the Scherrer equation. II-8. Electron microscopic view of the electrode catalyst

[0136] Using a transmission electron microscope (TEM; H9500; manufactured by Hitachi, Ltd.), the surface of the carbon support of each of the electrode catalysts in the examples and comparison examples was examined. A sample of each electrode catalyst was prepared using a wet dispersion method, and the structure of the carbon support was examined under conditions of an accelerating voltage of 300 kV and a magnification of 1,000,000x. II-9. CO adsorption quantity of the electrode catalyst

[0137] 0.05 g of each of the electrode catalysts from the examples and comparison examples were weighed into a container. Each sample in the container was heated to 80°C at a rate of 3°C / min in a stream of helium gas (100% He). Upon reaching 80°C, the internal atmosphere of the container was replaced with hydrogen gas (100% H₂). Next, the sample was reduced in a hydrogen atmosphere for 30 minutes. After the reduction was complete, the internal atmosphere of the container was replaced with helium gas (100% He), and then the sample was cooled to 30°C in a stream of helium gas. Finally, carbon monoxide (100% CO) was introduced into the container in a pulse (injection pressure: 100 kPa).Using a thermal conductivity detector (TCD), the amount of CO not bound to the catalyst was measured, and the difference between the amount of CO bound to the catalyst and the amount of CO released and not bound to the catalyst was determined as the CO adsorption rate (ml / g catalyst) of the electrode catalyst sample. This value was then divided by a Pt-to-support ratio to calculate the CO adsorption rate (ml / g Pt) per unit mass of Pt. II-10. Maintenance of the ECSA of the electrode catalyst

[0138] Based on a rotating disk electrode method using an aqueous 0.1MHClO4 solution as the electrolyte, the electrochemical surface area (ECSA) of each of the electrode catalysts in the examples and comparison examples was measured. A working electrode was coated with a predetermined amount of platinum. Under conditions of continuous nitrogen (N2) injection into the electrolyte solution, a potential cycle cleaning (50 mV to 1200 mV based on RHE, 600 cycles) was performed. Subsequently, a potential cycle durability test (400 mV to 1200 mV based on RHE, 5000 cycles) was conducted. The maintenance of the ECSA (%) was determined from the ECSA values ​​measured before and after the potential cycle durability test. III. Results of the assessment of the electrode catalyst III-1. Manufacturing conditions and physical properties of the electrode catalyst

[0139] The Fig. Sections 3A to 3C show a summary of the manufacturing conditions for electrode catalysts from examples and comparative examples, and the Fig. Sections 4A to 4C show the physical properties of the electrode catalysts. Furthermore, the Fig. 1A, Fig. 1B, Fig. 2A and Fig. 2B Transmission electron microscopy (TEM) images showing the carbon supports used to produce the electrode catalysts from examples and comparative examples, and the electrode catalysts from examples and comparative examples. Furthermore, the Fig. 5, Fig. 6, Fig. 7, Fig. 8, Fig. 9, Fig. 10, Fig. 11, Fig. 12, Fig. 13 to Fig. 14 Relationships between the respective physical properties of the electrode catalysts from examples and comparative examples. III-2. Platinum-supported electrode catalyst for one cathode

[0140] Surfaces of Ketjen and OSAB, commercially available carbon support materials with a large specific surface area, and a surface of TOCA BLACK #3855, a commercially available carbon support material with a small specific surface area, were examined using a transmission electron microscope (TEM). Fig. 1A and Fig. Figure 1B shows the TEM images of TOCA BLACK #3855. Furthermore, the crystallite size (Lc) of the (002) plane of carbon for each of the carbon support materials was measured by X-ray diffraction (XRD). Ketjen exhibited an Lc of 2.0 nm and OSAB an Lc of 1.8 nm. In contrast, TOCA BLACK, a commercially available carbon support material with a small specific surface area, exhibited an Lc of 5.3 nm.

[0141] A G-band FWHM and an intensity ratio (D / G ratio) of a D-band peak intensity I were determined using a Raman spectrum measurement. D to a G-band peak intensity I G Each of the carbon support materials was measured. Ketjen, a commercially available carbon support material with a large specific surface area, exhibited a G-band FWHM of 81 cm⁻¹. -1 and a D / G ratio of 1.18, and OSAB had a G-band FWHM of 68 cm -1 and a D / G ratio of 1.50. In contrast, TOCA BLACK #3855, a commercially available carbon support material with a small specific surface area, exhibited a G-band FWHM of 39 cm⁻¹. -1 and a D / G ratio of 0.34. The above results show that Ketjen and OSAB have a larger specific surface area but lower crystallinity compared to TOCA BLACK #3855.

[0142] As in Fig. As shown in Figure 5, it is clearly visible that for the platinum-supported electrode catalysts of Examples 1-1-1 to 1-1-16, the CO adsorption quantity is high even with a specific surface area of ​​170 m². 2 / g or less, 24 ml / g Pt or more. The specific surface areas of the platinum-supported electrode catalysts of the examples were in the range of 95 m². 2 / g up to 170 m 2 / g. In contrast, the CO adsorption quantity for the platinum-supported electrode catalysts of the comparison examples 1-1-1, 1-1-2, 1-1-3, 1-1-8 and 1-1-9, which used the same carbon support material (specific surface area: 79 m²) 2 / g) as in the examples without carrying out the oxidation step, and in the case of the platinum-supported electrode catalyst of comparison example 1-1-7, which was prepared using Ketjen (specific surface area: 800 m²) 2 / g) as a commercially available carbon support material with a large specific surface area without carrying out the oxidation step, less than 24 ml / g Pt.

[0143] As in Fig. As shown in Figure 6, the platinum-supported electrode catalysts of Examples 1-1-1 to 1-1-16 had a Lc of 5.0 nm or more, and a CO adsorption amount of 24 ml / g Pt or more. In contrast, the platinum-supported electrode catalyst of Comparative Example 1-1-7, which was prepared using Ketjen as a commercially available carbon support material without carrying out the oxidation step, had a Lc of 2.0 nm, and a CO adsorption amount of less than 24 ml / g Pt.

[0144] As in Fig. As shown in Figure 7, the D / G ratio of the platinum-supported electrode catalysts in Examples 1-1-1 to 1-1-16 was lower than 0.9, and the CO adsorption amount was 24 ml / g Pt or more. The D / G ratios of these examples ranged from 0.5 to less than 0.9. In contrast, the D / G ratio of the platinum-supported electrode catalysts in the comparison examples 1-1-1, 1-1-2, 1-1-3, 1-1-8, and 1-1-9, which were prepared using the same carbon material as in the examples but without performing the oxidation step, was 0.34, and the CO adsorption amount was lower than 24 ml / g Pt.Furthermore, in the platinum-supported electrode catalysts of comparison examples 1-1-10 to 1-1-12, which were prepared by carrying out the oxidation step of thermal oxidation of the same carbon support material as in the examples in a temperature range of 550°C to 570°C, the D / G ratio was in the range of 0.45 to 0.57, and the CO adsorption amount was less than 24 ml / g Pt. In contrast, in the platinum-supported electrode catalyst of comparison example 1-1-7, which was prepared using Ketjen as a commercially available carbon support material without carrying out the oxidation step, the D / G ratio was 1.17, and the CO adsorption amount was less than 24 ml / g Pt.

[0145] As in Fig. As shown in Figure 8, for the platinum-supported electrode catalysts of Examples 1-1-1 to 1-1-16, the crystallite size (Lc) of the (220) plane of platinum was 4.5 nm or less, and the CO adsorption amount was 24 ml / g Pt or more. The crystallite sizes of the (220) plane of platinum in the examples were greater than or equal to 3.2 nm and less than 4.1 nm. In contrast, in the platinum-supported electrode catalysts of comparison examples 1-1-1, 1-1-2 and 1-1-3, which were prepared by using the same carbon support material as in the examples without carrying out the oxidation step and by carrying out the step of applying the catalytic metal such that the same amount of platinum support (30 wt%) as in example 1-1-1 was obtained, the crystallite size of the (220) plane of platinum was 5.9 nm, and the CO adsorption amount was less than 24 ml / g Pt.Moreover, in the platinum-supported electrode catalysts of comparison examples 1-1-8 and 1-1-9, which were prepared by carrying out the step of applying the catalytic metal such that the same amount of platinum support (20 wt%) as in example 1-1-3 was obtained, the crystallite size of the (220) plane of platinum was 4.6 nm, and the CO adsorption amount was less than 24 ml / g Pt. Moreover, in the platinum-supported electrode catalysts of comparison examples 1-1-10 to 1-1-12, which were produced by carrying out the oxidation step of thermal oxidation of the same carbon support material as in the examples in a temperature range of 550°C to 570°C, the crystallite size of the (220) plane of platinum was in a range of 4.2 nm to 4.4 nm, and the CO adsorption amount was less than 24 ml / g Pt.In contrast, in the platinum-supported electrode catalyst of comparison example 1-1-7, which was prepared using Ketjen as a commercially available carbon support material without carrying out the oxidation step and by carrying out the step of applying the catalytic metal such that the same amount of platinum support (30 wt%) as in example 1-1-1 was obtained, the crystallite size of the (220) plane of platinum was 4.2 nm, and the CO adsorption quantity was less than 24 ml / g Pt.

[0146] The platinum-supported electrode catalysts of comparison examples 1-1-4 and 1-1-5 were prepared using the same procedure as described in International Publication WO 2005 / 106994 A1. As in Fig. As shown in Figure 5, the specific surface area of ​​the carbon support was approximately the same for the platinum-supported electrode catalysts of comparison examples 1-1-4 and 1-1-5 (123 m²). 2 / g) of those described in that document, however, the CO adsorption rate was less than 24 ml / g Pt. Moreover, as in Fig. Figure 8 shows that the crystallite sizes of the (220) plane of platinum of the platinum-supported electrode catalysts of the comparison examples are greater than 4.5 nm.

[0147] As in Fig. As shown in Figure 9, it is difficult to achieve both a high CO adsorption rate and a high maintenance of the ECSA with the platinum-supported electrode catalyst of the comparison examples. For example, in the platinum-supported electrode catalyst of comparison example 1-1-6, which exhibited a high CO adsorption rate (32 ml / g Pt), the maintenance of the ECSA was 58%. In contrast, in the platinum-supported electrode catalyst of comparison example 1-1-7, which exhibited a high maintenance of the ECSA (78%), the CO adsorption rate was 22 ml / g Pt. Similarly, in the platinum-supported electrode catalyst of comparison example 1-1-9, which exhibited a high maintenance of the ECSA (85%), the CO adsorption rate was 23 ml / g Pt. The drawing shows a dashed line connecting data points of the platinum-supported electrode catalysts of comparison examples 1-1-6 and 1-1-7.

[0148] In contrast, data points for CO adsorption rates and ECSA maintenance for the platinum-supported electrode catalysts of Examples 1-1-1 to 1-1-16 lie above the dashed line described above. As described above, the platinum-supported electrode catalysts of Examples 1-1-1 to 1-1-16 incorporated a carbon support exhibiting a high proportion of graphite structure and high crystallinity of the graphite structure. Under the operating conditions of a fuel cell, the carbon support with a high proportion of highly crystalline graphite exhibits high oxidation resistance. Accordingly, it is assumed that, compared to the platinum-supported electrode catalysts of the comparison examples 1-1-6 and 1-1-7, a higher CO adsorption rate and a higher ECSA maintenance rate could be achieved with the platinum-supported electrode catalysts of Examples 1-1-1 to 1-1-16. III-3. Platinum alloy-supported electrode catalyst for one cathode

[0149] As in the Fig. 10, Fig. 11, Fig. 12 to Fig. As shown in Figure 13, the specific surface area of ​​the platinum alloy-supported electrode catalysts of Examples 1-2-1 to 1-2-14 was exactly the same as in the case of the platinum-supported electrode catalysts: 170 m² 2 / g (especially in an area of ​​95 m) 2 / g up to 170 m 2 / g), the Lc was 5.0 nm or more, the D / G ratio was less than 0.9 (especially greater than or equal to 0.5 and less than 0.9), and the crystallite size of the (220) plane of platinum was 4.5 nm or less (especially greater than or equal to 3.2 nm and less than 4.1 nm). In this case, for the platinum alloy-supported electrode catalysts of Examples 1-2-1 to 1-2-14, the CO adsorption quantity was 18 ml / g Pt or more.

[0150] As in Fig. As shown in Figure 14, data points for CO adsorption rates and ECSA maintenance for the platinum alloy-supported electrode catalysts of Examples 1-2-1 to 1-2-14 are located above a dashed line connecting data points for the platinum alloy-supported electrode catalysts of Comparison Examples 1-2-2 and 1-2-3, just as in the case of the platinum alloy-supported electrode catalyst. Accordingly, it is assumed that, compared to the platinum alloy-supported electrode catalysts of Comparison Examples 1-2-2 and 1-2-3, a higher CO adsorption rate and a higher ECSA maintenance rate were achieved for the platinum alloy-supported electrode catalysts of Examples 1-2-14. III-4. Pore distribution of the carbon carrier

[0151] Fig. Figure 15 shows the pore distributions of a carbon support before thermal oxidation, after thermal oxidation at 600°C, after thermal oxidation at 610°C, after thermal oxidation at 620°C and after thermal oxidation at 630°C, and Fig. Figure 16 shows a relationship between the temperature of thermal oxidation and the pore volume.

[0152] As in Fig. As shown in Figure 15, the carbon support, thermally oxidized in a temperature range of 600°C to 630°C, exhibited additional pores with a radius in the range of 1.0 nm to 2.5 nm (particularly 1.7 nm to 1.9 nm) compared to the carbon support before thermal oxidation. Furthermore, as shown in Fig. As shown in Figure 16, the pore volume of the carbon support, which was thermally oxidized in a temperature range of 600°C to 630°C, increased compared to the carbon support before thermal oxidation. It is assumed that this increase in pore volume was caused by the formation of additional pores with the radius described above through thermal oxidation. Accordingly, it is assumed that the additional pores formed by thermal oxidation with the radius described above were used as support sites for the catalytic metal.

[0153] The formation of the pores resulting from the thermal oxidation of the carbon support was verified using TEM images of the carbon support. As shown in the Fig. 2A, Fig. 2B was shown in comparison to the surfaces ( Fig. 1A and Fig. 1B) of the untreated carbon support on the surface ( Fig. 2A) of the carbon support after carrying out the oxidation step by oxidizing agent treatment under the same conditions as in Examples 1-1-7, 1-1-8, 1-2-2, 1-2-5 and 1-2-7 and on the surface ( Fig. 2B) of the carbon support after carrying out the oxidation step by thermal oxidation under the same conditions as in Examples 1-1-12, 1-1-13, 1-2-10 and 1-2-11, the disturbance of the crystal structure was observed. III-5. Electrode catalyst for one anode

[0154] As in Fig. As shown in Figure 4C, the carbon support in the platinum-supported electrode catalysts for an anode of Examples 2-1-1 and 2-1-2 exhibited an Lc of 5.0 nm or more and a specific surface area in a range of 95 m². 2 / g up to 170 m 2 / g. In this case, the catalytic metal had a 220-plane platinum crystallite size of 4.5 nm or less and a CO adsorption capacity of 42 ml / g Pt or more. In contrast, for the platinum-supported electrode catalysts for one anode of the comparative examples 2-1-1 and 2-1-2, the specific surface area of ​​the carbon support was 79 m². 2 / g, and the CO adsorption amount was 34 ml / g Pt or 31 ml / g Pt. IV. Production of the electrode catalyst IV-1. Temperature of the thermal oxidation of the carbon support

[0155] Oxygen is present in the air, and so during the thermal oxidation of a carbon support in air (i.e., in the presence of oxygen), carbon within the support is burned, and the specific surface area increases. Therefore, the specific surface area can be controlled to a desired range by thermally oxidizing a carbon support with high crystallinity and a small specific surface area in air. However, if the temperature of the thermal oxidation in air rises too high, the combustion of carbon within the support progresses rapidly, making it more difficult to control the specific surface area.

[0156] A carbon support (TOCA BLACK; #3855; manufactured by Tokai Carbon Co., Ltd.) was thermally oxidized in air at temperatures ranging from room temperature to 1000°C, based on the oxidation step described in Example 1-1-11. Using a thermogravimetric (TG) analyzer (TG8120; manufactured by Rigaku Corporation), the temperature (°C) of a 5% mass reduction of the resulting carbon support was determined. Fig. Figure 17 shows a relationship between the temperature of the thermal oxidation of a carbon carrier in air and the temperature of a 5% mass reduction.

[0157] As in Fig. As shown in Figure 17, when the temperature of the thermal oxidation of the carbon support in air increased to 500°C or more, the temperature of the 5% mass reduction decreased linearly. When the temperature of the thermal oxidation in air rose to 630°C, the temperature of the 5% mass reduction fell to approximately 600°C. Accordingly, if the temperature of the thermal oxidation of the carbon support in air rises above 630°C, the oxidation resistance of the carbon support obtained as a product can decrease rapidly.

[0158] With reference to the fabrication of each of the platinum-supported electrode catalysts of Examples 1-11-1 to 1-1-16 and the comparison examples 1-1-10 to 1-1-12, it shows Fig. 18 a relationship between the temperature of the thermal oxidation of a carbon support in air, the amount of CO adsorption and the crystallite size of the (220) plane of platinum, Fig. Figure 19 shows a relationship between the temperature of the thermal oxidation of a carbon support in air, the amount of CO adsorption and the specific surface area of ​​the carbon support. Fig. Figure 20 shows a relationship between the temperature of the thermal oxidation of a carbon support in air, the amount of CO adsorption, and the oxygen concentration in the carbon support. Fig. Figure 21 shows a relationship between the temperature of the thermal oxidation of a carbon carrier in air, the amount of CO adsorption and the D / G ratio of the carbon carrier.

[0159] As in Fig. As shown in Figure 18, at a thermal oxidation temperature of the carbon support in air of 580°C or more, a platinum-supported electrode catalyst with a CO adsorption capacity of 24 ml / g Pt or more and a crystallite size of the (220) plane of platinum of 4.1 nm or less was obtained. It is assumed that the above result is due to the fact that at a thermal oxidation temperature of the carbon support in air of 580°C or more, the specific surface area of ​​the carbon support increased in parallel with the increase in the thermal oxidation temperature in air ( Fig. 19) Furthermore, at a temperature of thermal oxidation of the carbon support in air of 580°C or more, the oxygen concentration in the carbon support increased in parallel with the increase in the temperature of thermal oxidation in air ( Fig. 20) The above result shows that the carbon of the carbon support was oxidized due to the thermal oxidation of the carbon support; therefore, pores were formed which were able to be used as support sites for the catalytic metal ( Fig. 15 and Fig. 14). Furthermore, as in Fig. As shown in Figure 21, the D / G ratio of the carbon support increased with increasing temperature of the thermal oxidation of the carbon support in air. The above result shows that the proportion of a graphite structure of the carbon support decreased due to the thermal oxidation of the carbon support; therefore, the proportion of a non-graphite structure increased.

[0160] With reference to the fabrication of each of the platinum-supported electrode catalysts of Examples 1-1-1 to 1-1-10 and the comparative example 1-1-1, it shows Fig. 22 a relationship between the K / C ratio of a carbon support during treatment with an oxidizing agent (potassium permanganate), the amount of CO adsorption and the crystallite size of the (220) plane of platinum, Fig. Figure 23 shows a relationship between the K / C ratio of a carbon support during treatment with an oxidizing agent (potassium permanganate), the amount of CO adsorption and the specific surface area of ​​the carbon support. Fig. Figure 24 shows a relationship between the K / C ratio of a carbon support during treatment with an oxidizing agent (potassium permanganate), the amount of CO adsorption, and the oxygen concentration in the carbon support. Fig. Figure 25 shows a relationship between the K / C ratio of a carbon support during treatment with an oxidizing agent (potassium permanganate), the amount of CO adsorption and the D / G ratio of the carbon support.

[0161] As in Fig. As shown in Figure 22, when the K / C ratio of the carbon support was 2.5 mol% or more during treatment with an oxidizing agent (potassium permanganate), a platinum-supported carbon support with a CO adsorption capacity of 24 ml / g Pt or more and a crystallite size of the (220) plane of platinum of 4.1 nm or less was obtained. It is assumed that the above result is due to the fact that, at a K / C ratio of 2.5 mol% or more, the specific surface area of ​​the carbon support increased in parallel with the oxidation of the carbon support ( Fig. 23). Moreover, when the K / C ratio of the carbon support was 2.5 mol% or more during treatment with an oxidizing agent (potassium permanganate), the oxygen concentration in the carbon support increased in parallel with the temperature of the thermal oxidation of the carbon support in air ( Fig. 24) The preceding result shows that carbon of the carbon support was oxidized due to the thermal oxidation of the carbon support; therefore, pores were formed which were able to be used as support sites for the catalytic metal. Furthermore, as in Fig. As shown in Figure 25, when the K / C ratio of the carbon support increased during treatment with an oxidizing agent (potassium permanganate), the D / G ratio of the carbon support also increased. The above result shows that the proportion of graphite structures in the carbon support decreased due to treatment with an oxidizing agent; therefore, the proportion of non-graphite structures increased.

Claims

[1] Electrode catalyst for a fuel cell comprising: a carbon carrier; and a catalytic metal carried on the carbon support, wherein the catalytic metal is selected from platinum or a platinum alloy, wherein the carbon support has a crystallite size of the (002) plane of carbon in a range of 5.0 nm or more, at least pores with an average radius of 1.0 nm to 2.5 nm, and a specific surface area in a range of 95 m 2 / g up to 170 m 2 / g has, and the catalytic metal has a crystallite size of the (220) plane of platinum in a range of 4.5 nm or less. [2] Electrode catalyst according to claim 1, wherein the intensity ratio of a D-band peak intensity to a G-band peak intensity in a Raman spectrum of the carbon support is less than 0.

9. [3] Electrode catalyst according to claim 1 or 2, wherein the catalytic metal is platinum and has a CO adsorption quantity of 24 ml / g Pt or more. [4] Electrode catalyst according to claim 1 or 2, wherein the catalytic metal is a platinum alloy and has a CO adsorption quantity of 18 ml / g Pt or more. [5] Electrode catalyst according to one of claims 1 to 4, wherein the amount of the carrier of the catalytic metal is in the range of 15 wt% to 35 wt% based on a total mass of the electrode catalyst. [6] Electrode catalyst according to any one of claims 1 to 4, wherein a carrier amount of the catalytic metal is greater than or equal to 4.5 wt% and less than 15 wt% based on a total mass of the electrode catalyst. [7] Cathode, having: the electrode catalyst according to any one of claims 1 to 5. [8] Anode, having: the electrode catalyst according to one of claims 1 to 4 and 6. [9] Fuel cell, comprising: the cathode according to claim 7 and / or the anode according to claim 8. [10] Method for producing the electrode catalyst according to any one of claims 1 to 6, wherein the method comprises: Oxidizing a carbon support material by thermally oxidizing the carbon support material in a temperature range of 580°C to 650°C in the presence of oxygen or by treating the carbon support material with an oxidizing agent such that a carbon support with a crystallite size of the (002) plane of carbon in a range of 5.0 nm or more, at least pores with an average radius of 1.0 nm to 2.5 nm, and a specific surface area in a range of 95 m² 2 / g up to 170 m 2 / g is obtained; and Causing the carbon support and a catalytic metal material selected from platinum and a platinum alloy to react with each other in such a way that catalytic metal is deposited onto the carbon support. [11] Method according to claim 10, wherein the oxidizing agent contains potassium permanganate. [12] Method according to claim 10 or 11, wherein an amount of the oxidizing agent is in the range of 2.5 mol% to 14.5 mol% based on a total number of moles of carbon atoms of the carbon support material.

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