JP2015150480A - catalyst for fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a catalyst for a fuel cell capable of suppressing elution of a catalyst carrying conductor resulting from use in an extended period under an acidic atmosphere without lowering oxygen reduction activity of the catalyst, and thereby reducing decline of a fuel cell performance.SOLUTION: In a catalyst for a fuel cell, cubic crystal fine particles of chromium oxycarbide comprising two face-centered cubic sub-lattices, which are compounds comprising chromium, oxygen and carbon, are used, and a noble metal catalyst is carried thereon.

Description

  The present invention relates to a fuel cell catalyst.

  Low temperature fuel cells represented by polymer electrolyte fuel cells have a relatively low operating temperature and are easy to reduce in size and weight. Therefore, they can be used as power sources for mobile vehicles such as electric vehicles and small cogeneration systems. It is expected to spread. However, until now, it has not been widely spread. One of the causes is that platinum and platinum-based noble metal catalysts that are currently used are expensive and resource constraints are large. Therefore, the development of platinum alternative catalysts is essential for the widespread use of fuel cells in a wide range of fields in the future, and high power generation efficiency, especially under operating conditions with high utilization rates of cathode reaction gases (air, etc.) In addition, a performance capable of obtaining a high power density is required.

A polymer electrolyte fuel cell is formed by stacking a large number of cells including an electrolyte membrane, a catalyst layer, a gas diffusion layer, and a separator. In a single cell, a polymer solid electrolyte is sandwiched between an anode and a cathode, a fuel such as hydrogen or methanol is supplied to the anode, oxygen or air is supplied to the cathode, and an oxidation reaction such as H ₂ → 2H ⁺ + 2e ^{− is performed} at the anode. Is caused to undergo a reduction reaction of O ₂ + 4e ⁻ + 2H ₂ → 2H ₂ O at the cathode, and electric power is taken out. This reaction needs to be efficiently performed in the catalyst layer in the anode and the cathode, and the role played by the catalyst is large. In particular, since the oxygen reduction overvoltage is large and this causes a reduction in battery efficiency, the performance of the catalyst at the cathode of the oxygen reduction reaction electrode is very important for improving the performance of the fuel cell.
The catalyst layer is generally composed of a composite of an electrode catalyst and a solid polymer electrolyte. Conventionally, the electrode catalyst has a fine particle of noble metal such as platinum (Pt) (such as Pt black) and a conductive material such as carbon black. A material in which fine particles of noble metal such as Pt are supported on a carrier, a noble metal thin film formed by a method such as plating or sputtering on the surface of an electrolyte membrane, and the like are used. The electrode is generally formed by fixing the catalyst to a support member such as a carbon-based porous material such as carbon cloth or carbon paper, stainless steel, or a nickel net.

  Since platinum is expensive and has a limited amount of resources, non-platinum catalysts using transition metal oxides that can be replaced have been developed (see Patent Document 1). Low-platinization technology is also progressing, and electrolysis is performed using a conductive base material as a cathode, a platinum group metal as an anode, and an inorganic acid aqueous solution as an electrolytic solution. A platinum nanoparticle precipitation method (see Patent Document 2) for precipitation in an amount has also been developed. Due to the low platinum technology for such a catalyst, a highly efficient catalyst mainly composed of platinum is still important.

Conventionally, platinum-iron-cobalt (Pt-Fe-Co) -based catalysts (see Patent Document 3) and MxAyBz-based catalysts (M is palladium (Pd) and Pt, and A and B are platinum-based catalysts). , Titanium (Ti), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zirconium (Zr), niobium (Nb), molybdenum (Mo) , Tantalum (Ta), tungsten (W), gold (Au), one or more metals selected, x, y, z are atomic ratios (see Patent Document 4), or AaBbCcOx catalyst (A is Pt , Pd, rhodium (Rh), iridium (Ir), Au, etc., B is cerium (Ce), Mn, Ti, vanadium (V), Fe, Co, Cu, Nb, technetium (Tc), rhenium (Re) ) , Elements constituting one or more non-stoichiometric oxides selected from, osmium (Os), tin (Sn), lead (Pb), antimony (Sb), bismuth (Bi), praseodymium (Pr), W, C Is an arbitrary metal, a, b, c, and x are atomic ratios (see Patent Document 5). In addition, platinum-ruthenium (Pt—Ru), Pt—Fe, platinum—tungsten oxide (Pt—WO ₃ ) , Platinum-molybdenum oxide (Pt—MoO ₃ ) system, platinum-titanium oxide (Pt—TiO ₂ ) system, etc. have been developed and each has its characteristics. However, since the cathode is exposed to a highly oxidized state in terms of potential, platinum and platinum-based alloys, for example, dissolve or increase in particle size due to the potential cycle associated with the start and stop of fuel cell operation. Danger arises. In particular, since carbon-based conductors such as carbon black are used as catalyst-carrying conductors, carbon may be dissolved by hydrogen peroxide generated in the process of oxygen reduction at the cathode in an acidic atmosphere, and it will last for a long time. There was also a problem that it was not suitable for applications requiring durability. For this reason, there has been a strong demand for the development of a catalyst having high oxygen reducing ability using a supported conductor that does not corrode in an acidic atmosphere and has excellent durability.

International Publication WO2006 / 019128 Pamphlet International Publication WO2012 / 029162 Pamphlet Japanese Patent Laid-Open No. Sho 62-163746 JP 2008-305561 A JP 2006-66255 A

  It is an object of the present invention to suppress the elution of a catalyst-carrying conductor in an acidic atmosphere accompanying long-time use without reducing the oxygen reduction activity of the catalyst of the fuel cell, and to reduce the decrease in fuel cell performance. And

  The present inventor has found that the above problems can be solved by using a system composed of chromium oxycarbide and platinum having good conductivity and high corrosion resistance as a catalyst, and has reached the present invention.

The present invention is an invention of a fuel cell catalyst comprising a noble metal such as platinum and a catalyst-carrying conductor, and an invention of a fuel cell cathode containing the catalyst.
That is, the present invention is a fuel cell catalyst which is a compound composed of chromium, oxygen and carbon, and uses cubic chromium oxycarbide fine particles composed of two face-centered cubic lattices, on which a noble metal catalyst is supported. is there.
In the present invention, a carbon carrier is a compound composed of chromium, oxygen, and carbon, and a cubic chromium oxycarbide composed of two face-centered cubic lattices is supported, and a noble metal catalyst is supported on the surface thereof. The fuel cell catalyst.

  Since the present invention uses chromium oxycarbide having high corrosion resistance, it is optimally used in an environment where high corrosion resistance is required as an oxygen reduction catalyst for a fuel cell cathode using an acidic electrolyte such as a solid polymer membrane, phosphoric acid or sulfuric acid.

  According to the present invention, high oxygen reduction activity can be obtained compared with the conventional platinum catalyst on carbon black, and the high corrosion resistance of chromium oxycarbide makes it possible to reduce oxygen in the vicinity of platinum at the cathode in an acidic atmosphere. The resulting dissolution of carbon black can be reduced.

FIG. 1 is an X-ray diffraction pattern diagram of chromium oxycarbide, and FIG. 1 shows the X-ray diffraction intensity on the vertical axis and the incident angle (2θ (Cu-Kα) (deg)) on the horizontal axis. It is a cyclic voltammogram curve diagram (potential scanning speed: 50 mV / s) in 298K, 0.05 molar sulfuric acid under a nitrogen atmosphere of chromium oxycarbide / SUS304, the vertical axis represents current density, and the horizontal axis represents potential. . It is a cyclic voltammogram curve diagram (potential scanning speed: 5 mV / s) of chromium oxycarbide / SUS304 in nitrogen atmosphere and oxygen atmosphere in 298K, 0.05 molar sulfuric acid, the vertical axis indicates current density, and the horizontal axis Shows the potential. It is a cyclic voltammogram curve diagram (potential scanning speed: 50 mV / s) in 298K, 0.05 molar sulfuric acid under a nitrogen atmosphere of Pt / chromium oxycarbide / SUS304, the vertical axis indicates current density, and the horizontal axis indicates potential. Indicates. A current-potential curve (potential scanning speed: 1 mV / s) obtained from the difference in scanning current from a cyclic voltammogram curve in an oxygen atmosphere of Pt / chromium oxycarbide / SUS304 having a thickness of 5 nm in an oxygen and nitrogen atmosphere. Yes, the vertical axis represents current density, and the horizontal axis represents potential. The current value was converted to the true surface area of platinum calculated from FIG. FIG. 4 is a cyclic voltammogram curve (potential scanning speed: 50 mV / s) in 298 K, 0.05 molar sulfuric acid under a nitrogen atmosphere of Pt / glassy carbon, where the vertical axis indicates current density and the horizontal axis indicates potential. FIG. 5 is a current-potential curve diagram (potential scanning speed: 1 mV / s) obtained from a difference in scanning current from a cyclic voltammogram curve of Pt / glassy carbon of 5 nm thickness in an oxygen and nitrogen atmosphere under an oxygen atmosphere. The current density is shown on the axis, and the potential is shown on the horizontal axis. The current value was converted to the true surface area of platinum calculated from FIG. 0.9 V vs. Pt / chromium oxycarbide / GC electrode and Pt / GC electrode. FIG. 4 is a relationship diagram (potential scanning speed: 1 mV / s) between specific activity in RHE (current value per true surface area of platinum) and supported amount of Pt. The absolute value of the current value was converted to the true surface area of platinum, and the logarithm was shown.

  The inventors of the present invention pay attention to chromium oxycarbide, which has good conductivity, high corrosion resistance in sulfuric acid, hydrochloric acid, etc., and high denseness, and is excellent in acid corrosion environment blocking ability, and sputtering platinum on chromium oxycarbide. The present invention was made by preparing a catalyst and measuring its oxygen reduction activity.

Hereinafter, the fuel cell catalyst and the fuel cell cathode of the present invention will be described in detail.
A fuel cell catalyst is a compound composed of chromium, oxygen and carbon, and uses cubic chromium oxycarbide fine particles composed of two face-centered cubic lattices, on which a noble metal catalyst is supported.
Alternatively, a carbon carrier is a compound composed of chromium, oxygen, and carbon, and a cubic chromium oxycarbide composed of two face-centered cubic lattices is supported, and a noble metal catalyst is supported on the surface thereof. It is.
The compound composed of chromium, oxygen, and carbon is a compound composed of chromium (Cr), oxygen (O), and carbon (C) having a composition formula of CrxCyOz, and x, y, and z represent the ratio of the number of atoms, Two face-centered cubic sublattices having a relationship of 0.28 ≦ x ≦ 0.60, 0 <y, 0 <z, y + z = 1−x and a lattice constant a of 0.40 nm ≦ a ≦ 0.43 nm It is a cubic chromium oxycarbide consisting of The values of x and a include a fluctuation range depending on a film forming apparatus, a manufacturing method, and the like.

(Chromium oxycarbide)
Chromium oxycarbide is a cubic crystal similar to a sodium chloride (NaCl) type crystal composed of two face-centered cubic sublattices composed of chromium, carbon, and oxygen. Here, the cubic crystal similar to the NaCl type crystal is composed of two face centered cubic sublattices like the NaCl type crystal, but one face centered cubic sublattice is not necessarily occupied by a single element. A cubic crystal. The lattice constant of chromium oxycarbide prepared by the plasma CVD method is 0.410 nm and the composition ratio (x, y, z) of Cr, C, O written as Cr _x C _y O _z is X-ray photoelectron spectroscopy (XPS). : X-ray Photoelectron Spectroscopy) (0.5, 0.25, 0.25) (Japanese Journal of Applied Physics, Vol.28, pp.1450-1454 (1989) (non-patent literature) See 1).). In general, the lattice constant and chemical composition vary due to differences in manufacturing method and film forming conditions. For example, in the Journal of the American Ceramic Society, Vol. 84, pp. 1763-1766 (2001) (non-patent document 2), a lattice constant of 0.42 nm prepared by changing the film formation conditions by reactive sputtering is disclosed. Three chromium oxycarbide membranes are disclosed. The composition ratio (x, y, z) of Cr, C, and O of these three samples is (0.368, 0.215, 0) in the composition analysis by the electron probe micro-analyzer (EPMA) method. .417), (0.298, 0.045, 0.666), (0.38, 0.20, 0.421). The lattice constant created by the plasma CVD method and the reactive sputtering method is preferably not less than 0.40 nm and not more than 0.43 nm, more preferably not less than 0.41 nm and not more than 0, considering the fluctuation range due to the manufacturing method of about 0.01 nm. .42 nm or less. In addition, the chromium composition ratio x is preferably 0.298 or more and 0.50 or less in consideration of variation due to a film forming apparatus, a manufacturing method, and the like. Generally, errors in quantitative analysis by the surface analysis method are large, and it is said that X-ray photoelectron spectroscopy is about 10% (for example, see JP-A-8-110313), and electron beam microanalyzer method is about 1% (for example, , Hirofumi Kasada “EPMA structure and sample analysis example by KASADA”, [online], October 2002, Tottori University Engineering Department, [searched January 29, 2014], Internet <URL: http: // www .eng. tottori-u.ac.jp/~www_tec/epma/epma.html>). Considering such a measurement error, the chromium composition ratio x is not less than 0.28 and not more than 0.60.

  Chromium oxycarbide is a cubic crystal similar to the NaCl type and consists of two face-centered cubic sublattices. One of the sublattices is occupied by Cr as confirmed from the X-ray diffraction data. It can be said that other sublattices are occupied by C and O (see Non-Patent Document 1). Therefore, considering the effect of expanding the composition range due to the difference in film formation method and film formation conditions, the chromium composition ratio x is 0.28 or more and 0.60% or less in chromium oxycarbide, and carbon and oxygen remain together. It can be said that it occupies. In addition, it can be said that the range of the lattice constant is 0.40 or more and 0.43 nm or less in consideration of the difference in the film formation method. Further, if chromium is reduced, the electrical conductivity is lowered, and the catalyst efficiency is lowered as a whole system. If the chromium is increased, corrosion resistance is deteriorated.

  Chromium oxycarbide exhibits very high corrosion resistance in sulfuric acid and hydrochloric acid, and has an electric conductivity of 2 MS / m, which is equivalent to that of stainless steel (SUS304). In general, the film can be obtained in the form of a film by incomplete decomposition of hexacarbonylchromium or by synthesis in a plasma atmosphere using metallic chromium and hydrocarbons such as carbon dioxide and methane as raw materials. . The former incomplete decomposition of hexacarbonyl chromium is performed by a thermal CVD (Chemical Vapor Deposition) method, a plasma CVD method, or a photo CVD method, and the plasma CVD method is generally used. The latter plasma synthesis is performed by a reactive sputtering method or a reactive ion plating method.

  The size of the crystallites of chromium oxycarbide varies depending on the film forming method and the film forming conditions. It is known from X-ray diffraction that the size of crystallites is 8 nm or more and 80 nm or less in a chromium oxycarbide film produced by incomplete decomposition of hexacarbonyl chromium under various film formation conditions by plasma CVD. (Refer nonpatent literature 1.). There is a correlation between the size of the crystallite and the film hardness, that is, the residual stress inside the film, and the larger the crystallite, the higher the hardness. The hardness is about 20 GPa in terms of Vickers hardness. Therefore, the residual stress increases, leading to a decrease in adhesion and peeling, which is not preferable for coating. On the other hand, in a film having a small crystallite, since an amorphous part is included, the excellent properties of the original chromium oxycarbide are deteriorated, which is not preferable. Therefore, the size of the crystallite is considered to be 5 nm to 100 nm, which is wider than 8 nm to 80 nm in consideration of the difference in film forming method and film forming conditions, but more preferably 10 nm to 80 nm. More preferably, it is 20 nm or more and 60 nm or less.

(catalyst)
As one form of producing the catalyst, chromium oxycarbide is formed on a conductive carrier made of carbon by a plasma CVD method or a reactive sputtering method, and platinum (Pt) is deposited thereon by a sputtering method or the like. Produced. Carbon black is used as the conductive carrier made of carbon, but glassy carbon, graphite, graphite, activated carbon, and carbon nanotubes can also be used. In that case, it is possible to reduce elution of carbon black as the film thickness of chromium oxycarbide increases. Furthermore, if the film thickness of the chromium oxycarbide is large, the strength as the catalyst carrier particles increases. On the other hand, if the film thickness of the chromium oxycarbide is too thick, it is not preferable because the gas permeation into the catalyst layer is suppressed, and if it is too thin, the catalytic effect is lowered, which is not preferable. From such a viewpoint, the film thickness of the chromium oxycarbide is preferably 2 nm or more, more preferably 3 nm or more, further preferably 5 nm or more, preferably 200 nm or less, more preferably 100 nm or less, and further preferably 50 nm or less. To do. The thickness is preferably in the range of 2 nm to 200 nm, more preferably 3 nm to 100 nm, and even more preferably 5 nm to 50 nm.

  Further, chromium oxycarbide can be used as a conductive carrier instead of carbon. As one form in that case, a film thickness of about 10 μm is formed on an iron thin plate, and after the film formation, a chromium oxycarbide plate obtained by dissolving only the iron thin plate in nitric acid has a particle size of 40 nm or more by ball mill treatment. It is made into a porous structure that is finely divided into a range of 100 nm or less. As another form, it is also possible to use chromium oxycarbide fine powder dispersed on carbon black. In this case, the catalyst is at least one metal selected from the group consisting of platinum, palladium, rhodium, nickel and cobalt, or at least selected from the group of this metal and iron, cobalt, titanium, ruthenium, tungsten, molybdenum and niobium. An alloy with one kind of metal is further dispersed on a chromium oxycarbide fine powder by standard treatment.

  This standard treatment uses a known method such as dissolving the catalyst in an acid and depositing it, or decomposing and depositing a catalyst metal precursor (such as an ammine complex) in a gas phase such as an inert gas. Do it. The obtained catalyst-supported chromium oxycarbide / carbon black fine powder of the metal catalyst-supported conductor is in a ratio of 1:10 to 1:20 using a polymer electrolyte (for example, 5% Nafion (registered trademark) solution). After being applied in the form of an ink and applied to a fuel cell diffusion layer (trade name: carbon paper), it is pressure-bonded with a thermo-compression bonding device together with a solid polymer electrolyte membrane (Nafion (registered trademark) membrane, etc.). -Obtain a cathode for a fuel cell of an electrode assembly.

  Hereinafter, the fuel cell catalyst of the present invention will be described in detail with reference to Examples and Comparative Examples. In this example, an evaluation result by electrochemical measurement in a sulfuric acid solution, which is often employed as a pre-test of the fuel cell test, was employed.

  Using hexacarbonylchromium as a raw material, a chromium oxycarbide film having a thickness of 5 nm was formed on stainless steel (for example, SUS304) at 350 ° C. by plasma CVD. FIG. 1 shows the X-ray diffraction pattern. Cu-Kα (8.048 keV) represents a characteristic X-ray. As shown in FIG. 1, it can be seen that a chromium oxycarbide film having a cubic crystal structure and a lattice constant of 0.41 nm is formed on the SUS304 plate. The micro Vickers hardness of this film was 20 GPa or more.

FIG. 2 shows a cyclic voltammogram curve of the obtained chromium oxycarbide / SUS304 in a 298 K, 0.05 molar sulfuric acid under a nitrogen atmosphere. As shown in FIG. 2, the shape of the curve does not change even if the scan is repeated 50 times at a potential scan speed of 0.05 mV to 1.2 V and 50 mV / s, and chromium oxycarbide is very stable in sulfuric acid. It can be seen that it is.
In the cyclic voltammogram curve shown in FIG. 2, the upper curve (plus side) represents an oxidation wave, and the lower curve (minus side) represents a reduction wave. When the potential is 1.0 V or more, an electric current is observed due to the generation of oxygen, and when the electric potential is 0.05 V or less, an electric current is generated due to the generation of hydrogen. In a potential range other than the above, from 0.05 V to 1.0 V, for example, almost no current flows due to film dissolution. Further, there is no change in current even in repeated potential scanning, and it is stable. The current is not 0 due to the charging current due to the electric double layer capacity at the potential scanning speed of 50 mV / s, not the dissolution current. On the other hand, under the supply of oxygen gas, a reduction current flows as shown in FIG. 3. From this, it can be concluded that chromium oxycarbide is very stable even in an oxidizing atmosphere and has oxygen gas reducing ability.
As a result of examining the corrosion resistance of iron and stainless steel under the same conditions, a dissolution current was observed in the case where chromium oxycarbide was not coated. On the other hand, it was recognized that the corrosion resistance of the chrome oxycarbide coating was significantly improved.

  FIG. 3 shows a cyclic voltammogram curve of the obtained chromium oxycarbide / SUS304 in a 298K, 0.05 molar sulfuric acid under a nitrogen atmosphere and an oxygen atmosphere. One scanning was performed at a potential scanning speed of 5 mV / s at 0.05 V or more and 1.2 V or less. As a result, as shown in FIG. 3, in the oxygen atmosphere, a large reduction current was observed at 0.6 V (vs. RHE: measured with reference to the reversible hydrogen electrode) or lower than in the nitrogen atmosphere, and this was the first in the world. The oxygen reduction catalytic activity of chromium oxycarbide was observed. The activity of chromium oxycarbide as an oxygen reduction catalyst is not so high.

  Next, platinum was deposited at a thickness of 1 nm, 2 nm, 5 nm, 10 nm, 20 nm, or 40 nm on the surface of chromium oxycarbide / SUS304 by sputtering.

  FIG. 4 shows a cyclic voltammogram curve of the obtained Pt / chromium oxycarbide / SUS304 in a 298K, 0.05 molar sulfuric acid in a nitrogen atmosphere. One scan was performed at a potential scan speed of 50 mV / s at 0.05 V or more and 1.2 V or less. As a result, as shown in FIG. 4, it is understood that the hydrogen adsorption / desorption peak increases as the platinum film thickness (supported amount) increases.

  The cyclic voltammogram curve of 5 nm-thick Pt / chromium oxycarbide / SUS304 was obtained under the same conditions as the cyclic voltammogram curve measurement conditions in FIG. 4 except for the condition where the potential scanning speed was 1 mV / s in an oxygen atmosphere. FIG. 5 shows a current-potential curve obtained from the difference in scanning current.

  Next, platinum was deposited to a thickness of 2, 5, and 20 nm on the surface of glassy carbon (hereinafter sometimes referred to as GC) by sputtering.

  FIG. 6 shows a cyclic voltammogram curve of the obtained Pt / glassy carbon in a 298K, 0.05 molar sulfuric acid under a nitrogen atmosphere. One scan was performed at a potential scan speed of 50 mV / s at 0.05 V or more and 1.2 V or less. As a result, as shown in FIG. 6, it is understood that the hydrogen adsorption / desorption peak increases as the film thickness (supported amount) of platinum (Pt) increases.

  A cyclic voltammogram curve of a Pt / glassy carbon having a thickness of 5 nm was obtained under the same conditions as the cyclic voltammogram curve measurement conditions in FIG. 6 except for the potential scanning speed of 1 mV / s in an oxygen atmosphere. FIG. 7 shows a current-potential curve obtained from the difference.

  The current-potential curve of FIG. 5 is compared with the current-potential curve of FIG. 7, and the current-potential curve obtained from the difference between the scanning currents of oxygen and nitrogen atmospheres of Pt / chromium oxycarbide / SUS304 is Pt / glassy. It can be seen that the oxygen reduction current density is larger than that of carbon. This indicates that Pt / chromium oxycarbide / SUS304 has higher oxygen reduction activity than Pt / glassy carbon.

FIG. 8 shows 0.9 V vs. Pt / chromium oxycarbide / GC electrode and Pt / GC electrode. The relationship between the specific activity in RHE and the amount of Pt supported was shown. As the amount of Pt supported (film thickness) decreased, the oxygen reduction current (absolute value) per platinum amount increased significantly. This is considered to be due to the influence of the size effect due to the fine Pt particles with the decrease in the amount of Pt supported. Further, in the case of cathode scanning, Pt / Cr ₂ CO / GC was shown to be highly active as compared with Pt / GC. It was found that Cr ₂ CO can be expected as a carrier that improves the activity of the Pt catalyst.

The catalyst of the present invention can be used in oxygen reduction reactions such as hydrogen-oxygen fuel cells, methanol-oxygen fuel cells, ethanol-oxygen fuel cells and other direct liquid fuel cells, and metal-air cell cathodes, It is useful as a redox catalyst for an electrochemical system used in contact with an acidic electrolyte in a reaction involving oxygen generation.

Claims (5)

  A fuel cell catalyst comprising a compound of chromium, oxygen and carbon, and cubic chromium oxycarbide fine particles comprising two face-centered cubic sublattices, on which a noble metal catalyst is supported.   Fuel in which a carbon carrier is a compound composed of chromium, oxygen, and carbon, and a cubic chromium oxycarbide composed of two face-centered cubic sublattices is supported, and a noble metal catalyst is supported on the surface. Battery catalyst.   The compound composed of chromium, oxygen, and carbon is a compound composed of chromium, oxygen, and carbon having a composition formula of CrxCyOz, and x, y, and z represent a ratio of the number of atoms, and 0.28 ≦ x ≦ 0. 60, 0 <y, 0 <z, y + z = 1-x, and cubic chromium oxycarbide composed of two face-centered cubic sublattices having a lattice constant a of 0.40 nm ≦ a ≦ 0.43 nm The fuel cell catalyst according to claim 1 or 2.   The noble metal catalyst is at least one metal selected from the group consisting of platinum, palladium, and rhodium, or at least one metal selected from the group of this metal and iron, cobalt, titanium, ruthenium, tungsten, molybdenum, and niobium. The fuel cell catalyst according to any one of claims 1 to 3, which is an alloy with a metal. A fuel cell having a catalyst layer comprising a metal catalyst-supporting conductor and a polymer electrolyte, wherein the fuel cell catalyst according to any one of claims 1 to 4 is supported. Cathode.

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