Metal-supported catalysts, electrodes and batteries

Abstract

To provide a metal-loaded catalyst that exhibits both an excellent durability and an excellent catalytic function and also provide an electrode and a battery.SOLUTION: A metal-loaded catalyst comprises a carbon support and noble metal-containing catalyst metal particles supported by the carbon support. In the Raman spectrum provided by Raman spectroscopy, the half width at half maximum of the D band having a peak top in the vicinity of a Raman shift of 1340 cm-1 is at most 50.0 cm-1. The proportion of carbon anchoring is at least 15.0%.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a supported metal catalyst, an electrode, and a battery. [Background technology]

[0002] Patent Document 1 describes a catalyst comprising a support having micropores and catalyst particles, wherein the support contains carbon and at least a portion of the catalyst particles are embedded in the support.

[0003] Patent Document 2 describes a catalyst comprising a catalyst carrier and a catalytic metal supported on the catalyst carrier, the catalyst having a BET specific surface area of ​​1200 m per weight of the carrier. 2 / g of support and characterized in that the amount of acidic groups per weight of support is equal to or greater than 0.7 mmol / g of support.

[0004] Patent Document 3 describes a catalyst comprising catalyst particles and a carbon film covering the surface of the catalyst particles, wherein the content of chloride ions per unit surface area of ​​the catalyst particles is 12.5 μg / m 2 Electrocatalysts are described that are less than [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-207072 [Patent Document 2] International Publication No. 2014 / 175099 [Patent Document 3] Japanese Patent Application Publication No. 2020-136109 Summary of the Invention [Problem to be solved by the invention]

[0006] However, it has been difficult to realize a metal-supported catalyst that combines excellent durability and excellent catalytic function.

[0007] The present invention has been made in view of the above-mentioned problems, and one of its objects is to provide a metal-supported catalyst, an electrode, and a battery that combine excellent durability and excellent catalytic function. [Means for solving the problem]

[0008] A metal-supported catalyst according to one embodiment of the present invention for solving the above problems is a metal-supported catalyst comprising a carbon support and catalytic metal particles containing a noble metal supported on the carbon support, wherein the catalyst has a Raman shift of 1340 cm in a Raman spectrum obtained by Raman spectroscopy. -1 The half-width at half maximum of the D band with a peak top near -1 or less, and the carbon anchoring ratio calculated by the following formula (I) is 15.0% or more. According to the present invention, there is provided a metal-supported catalyst that combines excellent durability and excellent catalytic function. JPEG0007812251000001.jpg21170 (In the following formula (I), the "electrochemically effective specific surface area" and the "geometric specific surface area" respectively represent the electrochemically effective specific surface area (m 2 / g-noble metal) and geometric specific surface area (m 2 / g-precious metals).

[0009] The metal-supported catalyst may have an average pore diameter of 8.0 nm or less. The metal-supported catalyst may have a volume (cm) of pores having a pore diameter of 5 nm or more and 70 nm or less. 3 / g of carbon support) 3 / g-carbon support) ratio may be 1.5 or more. 2 / g-carbon support) or more.

[0010] The metal-supported catalyst may be configured such that the ratio of the weight of the noble metal to the weight of the metal-supported catalyst is 30% by weight or more. Also, the metal-supported catalyst may be configured such that the electrochemically effective specific surface area of ​​the noble metal is 45 (m2 The metal-supported catalyst may have a specific geometric surface area of ​​the noble metal of 52 (m / g-noble metal) or more. 2 / g-precious metal) or more.

[0011] In addition, the metal-supported catalyst has a carbon anchoring amount calculated by the following formula (II) of 5.0 m 2 / g or more. JPEG0007812251000002.jpg28170 (In the above formula (II), "precious metal content (wt%)" is the ratio of the weight of the precious metal to the weight of the metal-supported catalyst, and "geometric specific surface area" and "electrochemically effective specific surface area" are the geometric specific surface areas (m 2 / g-noble metal) and electrochemically effective specific surface area (m 2 / g-precious metals).

[0012] The metal-supported catalyst may have a durability index calculated by the following formula (III) of 0.50 cm or more. JPEG0007812251000003.jpg21170 (In the above formula (III), the "carbon anchoring ratio (%)" is calculated by the formula (I), and the "Raman D half width at half maximum" is the half width at half maximum of the D band (cm -1 )

[0013] According to one embodiment of the present invention, there is provided an electrode having excellent properties, which comprises any one of the above-described metal-supported catalysts.

[0014] According to one embodiment of the present invention, a battery having excellent characteristics is provided, the battery including the electrode. [Effects of the Invention]

[0015] According to the present invention, a metal-supported catalyst, an electrode, and a battery are provided that have both excellent durability and excellent catalytic function. [Brief explanation of the drawings]

[0016] [Figure 1] FIG. 1 is an explanatory diagram showing an example of the results of analyzing a Raman spectrum obtained by Raman spectroscopy of a metal-supported catalyst in an example according to the present embodiment. [Figure 2A] FIG. 2 is an explanatory diagram showing an example of the results of analyzing an X-ray diffraction pattern obtained by powder X-ray diffraction of a metal-supported catalyst in an example according to the present embodiment. [Figure 2B] FIG. 10 is an explanatory diagram showing another example of the results of analyzing the X-ray diffraction pattern obtained by powder X-ray diffraction of the metal-supported catalyst in the example according to the present embodiment. [Figure 3] FIG. 2 is an explanatory diagram showing an example of the results of analyzing an X-ray diffraction pattern obtained by powder X-ray diffraction of a metal-supported catalyst in an example according to the present embodiment. [Figure 4A] FIG. 1 is an explanatory diagram showing the manufacturing conditions of a metal-supported catalyst in an example according to the present embodiment, and the results of evaluating the characteristics of a fuel cell including the metal-supported catalyst. [Figure 4B] FIG. 1 is an explanatory diagram showing the results of evaluating the characteristics of a metal-supported catalyst in an example according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0017] An embodiment of the present invention will be described below, but the present invention is not limited to the example shown in this embodiment.

[0018] The metal-supported catalyst according to this embodiment (hereinafter referred to as "the catalyst") includes a carbon support and catalytic metal particles containing a noble metal supported on the carbon support.

[0019] The carbon support contained in the catalyst is a carbon material mainly composed of carbon. The carbon content of the carbon support may be, for example, 70% by weight or more, preferably 75% by weight or more, more preferably 80% by weight or more, and particularly preferably 85% by weight or more.

[0020] The carbon content of the carbon support may be, for example, 100% by weight or less, 95% by weight or less, or 90% by weight or less. The carbon content of the carbon support may be specified by any combination of any of the above-mentioned lower limit values ​​and any of the above-mentioned upper limit values. The carbon content of the carbon support is obtained by elemental analysis (combustion method).

[0021] The carbon support is preferably a carbonized material. The carbonized material is obtained by carbonizing a raw material containing organic matter. The content of the organic matter in the raw material for carbonization may be, for example, 5% by weight or more and 90% by weight or less, and preferably 10% by weight or more and 80% by weight or less.

[0022] The organic matter contained in the raw material is not particularly limited as long as it can be carbonized. The organic compounds may be polymers (e.g., thermosets and / or thermoplastics). and / or may be organic compounds with lower molecular weights.

[0023] The carbon support preferably contains nitrogen. That is, the carbon support preferably contains a nitrogen atom in its carbon structure. The nitrogen-containing carbon support is preferably a nitrogen-containing carbonized material. The nitrogen-containing carbonized material is obtained, for example, by carbonizing a raw material containing a nitrogen-containing organic substance. The nitrogen-containing organic substance preferably contains a nitrogen-containing organic compound. The nitrogen-containing organic compound is not particularly limited as long as it is an organic compound containing a nitrogen atom in its molecule. Furthermore, the nitrogen contained in the carbon support may be introduced by nitrogen doping treatment.

[0024] The nitrogen content of the carbon support may be, for example, 0.10 wt% or more, preferably 0.15 wt% or more, more preferably 0.20 wt% or more, even more preferably 0.25 wt% or more, and particularly preferably 0.30 wt% or more. The nitrogen content of the carbon support may be, for example, 10.00 wt% or less. The nitrogen content of the carbon support is obtained by elemental analysis (combustion method) of the carbon support.

[0025] The carbon support is preferably a carbonized material obtained by carbonizing a raw material containing an organic substance and a metal. In this case, the carbon support may be a carbonized material that has been subjected to a metal removal treatment after carbonization. The metal removal treatment is a treatment for reducing the amount of metals derived from the raw material contained in the carbonized material. Specifically, the metal removal treatment is preferably, for example, an acid washing treatment and / or an electrolytic treatment.

[0026] When the carbon support is a carbonized material obtained by carbonizing a raw material containing an organic substance and a metal, the carbon support may contain a metal (hereinafter referred to as a "raw material metal") derived from the raw material of the carbonization. In this case, the carbon support contains the raw material metal inside the skeleton that constitutes its porous structure. Even when the carbon support is a carbonized material produced through a metal removal treatment as described above, the raw material metal remains inside the skeleton of the carbon support. Of the raw material metals contained in the carbon support, the weight of the raw material metal contained inside the skeleton of the carbon support may be greater than the weight of the raw material metal contained on the surface of the skeleton of the carbon support.

[0027] The raw material metal inside the skeleton of the carbon support can be detected, for example, by subjecting the skeleton to a surface etching treatment and analyzing the cross section exposed by the etching treatment. That is, in this case, when one particle of the carbon support is subjected to an etching treatment, the raw material metal is detected on the cross section of the particle exposed by the etching treatment. The raw material metal contained in the carbon support can be detected, for example, by inductively coupled plasma atomic emission spectroscopy of the carbon support.

[0028] The raw metal content of the carbon support (the ratio of the weight of the raw metal contained in the carbon support to the weight of the carbon support) may be, for example, 0.001 wt % or more, 0.005 wt % or more, 0.01 wt % or more, or 0.02 wt % or more. The raw metal content of the carbon support may be, for example, 5 wt % or less, 4 wt % or less, 3 wt % or less, 2 wt % or less, 1 wt % or less, 0.8 wt % or less, or 0.5 wt % or less. The raw metal content of the carbon support may be specified by any combination of any of the above-mentioned lower limit values ​​and any of the above-mentioned upper limit values. The raw metal content of the carbon support may be obtained, for example, by inductively coupled plasma atomic emission spectroscopy of the carbon support.

[0029] The raw material metal is preferably a transition metal, that is, the raw material metal is preferably a transition metal belonging to Groups 3 to 12 of the periodic table, and particularly preferably a transition metal belonging to the fourth period of Groups 3 to 12 of the periodic table.

[0030] The source metal may be a transition metal other than platinum, or a transition metal other than a noble metal (e.g., ruthenium (Ru), palladium (Pd), rhodium (Rh), silver (Ag), osmium (Os), iridium (Ir), platinum (Pt), and gold (Au)).

[0031] Specifically, the raw material metal may be, for example, one or more selected from the group consisting of scandium (Sc), titanium (Ti), vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zinc (Zn), yttrium (Y), zirconium (Zr), niobium (Nb), molybdenum (Mo), ruthenium (Ru), rhodium (Rh), palladium (Pd), silver (Ag), lanthanides (e.g., gadolinium (Gd)), and actinides, and is preferably one or more selected from the group consisting of Fe, Co, Ni, Cu, and Zn, more preferably one or more selected from the group consisting of Fe, Co, Ni, and Zn, and particularly preferably one or more selected from the group consisting of Co, Ni, and Zn.

[0032] Carbonization in the production of a carbonized material is carried out by heating the raw material at a temperature at which the organic matter contained in the raw material is carbonized. The carbonization temperature is not particularly limited as long as it is a temperature at which the raw material is carbonized, and is, for example, preferably 1200°C or higher, more preferably 1300°C or higher, even more preferably 1400°C or higher, and particularly preferably 1500°C or higher.

[0033] The carbonization temperature may be, for example, 3000°C or lower, preferably 2500°C or lower, and particularly preferably 2000°C or lower. The carbonization temperature may be specified by any combination of any of the above-mentioned lower limit values ​​and any of the above-mentioned upper limit values. The rate of temperature rise to the carbonization temperature is not particularly limited, and may be, for example, 0.5°C / min or higher and 300°C / min or lower. Carbonization is preferably carried out in an inert atmosphere such as a nitrogen atmosphere.

[0034] Carbonization may be carried out under normal pressure (atmospheric pressure), but is preferably carried out under pressure (under pressure higher than atmospheric pressure). When carbonization is carried out under pressure, the pressure of the atmosphere in which the carbonization is carried out may be, for example, 0.05 MPa or more in gauge pressure, preferably 0.15 MPa or more in gauge pressure, more preferably 0.20 MPa or more, even more preferably 0.40 MPa or more, and particularly preferably 0.50 MPa or more. The upper limit of the pressure of the atmosphere in which the carbonization is carried out is not particularly limited, but the pressure may be, for example, 10 MPa or less in gauge pressure.

[0035] The carbon support is preferably a carbonized material that has been subjected to a graphitization treatment after carbonization, i.e., the carbon support is preferably a carbonized material obtained by, for example, carbonizing a raw material containing an organic substance and then graphitizing the carbonized material.

[0036] The graphitization treatment is carried out by heating the carbonized material at a temperature at which graphitization proceeds. The heating temperature at which the carbonized material is heated in the graphitization treatment is not particularly limited as long as it is a temperature at which graphitization proceeds in the carbonized material, but is preferably a temperature higher than the carbonization temperature for obtaining the carbonized material.

[0037] Specifically, the heating temperature in the graphitization treatment may be, for example, 1300°C or higher, preferably 1400°C or higher, more preferably 1500°C or higher, even more preferably 1600°C or higher, still more preferably 1700°C or higher, still more preferably 1750°C or higher, and particularly preferably 1800°C or higher.

[0038] The heating temperature in the graphitization treatment may be, for example, 3000°C or lower, preferably 2500°C or lower, more preferably 2400°C or lower, even more preferably 2300°C or lower, still more preferably 2250°C or lower, still more preferably 2200°C or lower, still more preferably 2150°C or lower, and particularly preferably 2100°C or lower. The heating temperature in the graphitization treatment may be specified by any combination of any of the above-mentioned lower limit values ​​and any of the above-mentioned upper limit values. The rate of temperature rise up to the heating temperature in the graphitization treatment is not particularly limited and may be, for example, 0.5°C / min or higher and 300°C / min or lower. The graphitization treatment is preferably performed in an inert atmosphere such as a nitrogen atmosphere.

[0039] When the carbon support is a carbonized material that has been subjected to a graphitization treatment after carbonization, it is preferable that the carbonized material after the graphitization treatment is not subjected to a pulverization treatment. That is, in the production of the carbon support, for example, it is preferable that the carbonized material obtained by carbonizing a raw material is subjected to a pulverization treatment to adjust its median diameter, and then the pulverized carbonized material is subjected to a graphitization treatment, but the carbonized material after the graphitization treatment is not subjected to a pulverization treatment.

[0040] The carbon support is preferably a carbon material that exhibits catalytic activity. That is, in this case, the carbon support is a carbon catalyst that exhibits catalytic activity by itself. The carbon support that is a carbon catalyst is preferably a carbonized material obtained by carbonizing a raw material containing an organic substance and a metal, as described above.

[0041] The catalytic activity exhibited by the carbon support is preferably, for example, reduction activity and / or oxidation activity, more preferably oxygen reduction activity and / or hydrogen oxidation activity, and particularly preferably at least oxygen reduction activity.

[0042] In this catalyst, the catalytic metal particles supported on the carbon support contain a precious metal. The catalytic metal particles containing a precious metal include a precious metal that is not alloyed (hereinafter sometimes referred to as a "pure precious metal") and / or a precious metal alloy. A precious metal alloy is an alloy of a precious metal and a metal other than a precious metal (hereinafter referred to as a "non-precious metal"). In other words, a precious metal alloy contains one or more precious metals and one or more non-precious metals.

[0043] The noble metal is preferably one or more selected from the group consisting of ruthenium (Ru), palladium (Pd), rhodium (Rh), silver (Ag), osmium (Os), iridium (Ir), platinum (Pt), and gold (Au), more preferably one or more selected from the group consisting of Ru, Pd, Rh, Ir, and Pt, and particularly preferably Pt.

[0044] That is, the catalytic metal particles preferably contain platinum. The catalytic metal particles containing platinum contain platinum that has not formed an alloy (hereinafter, sometimes referred to as "pure platinum") and / or a platinum alloy. A platinum alloy is an alloy of platinum and a non-precious metal. That is, a platinum alloy contains platinum and one or more non-precious metals. Furthermore, the platinum alloy may further contain one or more other precious metals, or may not contain other precious metals.

[0045] The non-precious metal constituting the precious metal alloy is not particularly limited as long as it is a metal other than a precious metal that forms an alloy with the precious metal, but is preferably a transition metal other than a precious metal. Specifically, the non-precious metal contained in the precious metal alloy is preferably one or more selected from the group consisting of titanium (Ti), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), niobium (Nb), and cerium (Ce), more preferably one or more selected from the group consisting of Fe, Co, and Ni, and particularly preferably one or more selected from the group consisting of Co and Ni.

[0046] When the carbon support is a carbonized material of a raw material containing an organic substance and a raw material metal, the catalytic metal particles supported on the carbon support may contain the same type of metal as the raw material metal, or may not contain the same type of metal as the raw material metal.

[0047] The catalytic activity of the catalytic metal particles is not particularly limited as long as the effects of the present invention are obtained. However, the catalytic metal particles preferably exhibit, for example, reduction activity and / or oxidation activity, more preferably oxygen reduction activity and / or hydrogen oxidation activity, and particularly preferably at least oxygen reduction activity.

[0048] This catalyst exhibited a Raman shift of 1340 cm in the Raman spectrum obtained by Raman spectroscopy. -1 Around (specifically, for example, 1320 cm -1 Above, 1360cm -1 The half width at half maximum of the D band having a peak top within the range of 50.0 (cm -1 ) It is preferred that the carbon structure be:

[0049] The Raman D half width at half maximum of this catalyst is, for example, 48.0 cm -1 It is more preferable that it is 46.0 cm or less. -1 More preferably, it is 44.0 cm or less. -1 More preferably, it is 42.0 cm or less. -1 More preferably, it is 40.0 cm or less. -1 More preferably, it is 38.0 cm or less. -1 Preferably less than 36.0cm -1 It is more preferable that it is 34.0 cm or less. -1 More preferably, it is 32.0 cm or less. -1 More preferably, it is 30.0 cm or less. -1 More preferably, it is 28.0 cm or less. -1 More preferably, it is 26.0 cm or less. -1 More preferably, it is 25.0 cm or less. -1It is particularly preferred that:

[0050] The Raman D half width at half maximum of the carbon structure of the catalyst is, for example, 20.0 cm -1 It may be more than 21.0cm -1 It is preferable that it is 22.0 cm or more. -1 More preferably, it is 22.5cm or more. -1 The Raman D half width at half maximum of the present catalyst may be specified by any combination of any of the above-mentioned lower limit values ​​and any of the above-mentioned upper limit values.

[0051] According to a reference (A. Sadezky et al., Carbon 43 (2005) 1731-1742), in the Raman spectrum of a carbon material, the D band is a component derived from carbon atoms close to a disordered lattice, such as the edge portion of a graphene layer. The half-width at half maximum of the D band indicates the crystallinity of the carbon around the edge portion. In other words, the higher the crystallinity of the carbon around the edge portion of a carbon structure, the smaller the Raman D half-width at half maximum of the carbon structure. Therefore, a carbon structure that exhibits a Raman D half-width at half maximum of the above-mentioned upper limit or less contains highly crystalline carbon around the edge portion, which contributes to improved durability.

[0052] On the other hand, a carbon structure exhibiting a Raman D half width at half maximum that is too small has too high a crystallinity of carbon around the edge portion, making it less suitable for supporting catalytic metal particles. In contrast, a carbon structure exhibiting a Raman D half width at half maximum that is equal to or greater than the above-mentioned lower limit contains carbon with an appropriate degree of crystallinity around the edge portion, making it more suitable for supporting catalytic metal particles, thereby contributing to improving the durability and / or catalytic function of the metal-supported catalyst.

[0053] This catalyst has a BET specific surface area of ​​350 (m 2 / g-carbon support) or more. In this specification, the numerical unit " / g-carbon support" indicates a value per 1g of the carbon support contained in the present catalyst. On the other hand, the numerical unit " / g" indicates a value per 1g of the present catalyst.

[0054] The BET specific surface area of ​​the catalyst is, for example, 400 (m 2 / g-carbon support) or more is more preferable, and 450 (m 2 / g-carbon support) or more is more preferable, and 2 / g-carbon support) or more is more preferable, and 550 (m 2 / g-carbon support) or more is more preferable, and 2 / g-carbon support) or more is more preferable, and 650 (m 2 / g-carbon support) or more is more preferable, and 2 / g-carbon support) or more is more preferable, and 2 / g-carbon support) or more is more preferable, and 2 / g-carbon support) or more is more preferable, and 2 / g-carbon support) or more is more preferable, and 2 / g-carbon support) or more is more preferable, and 2 / g-carbon support) or more is more preferable, and 2 / g-carbon support) or more is more preferable, and 2 / g-carbon support) or more is more preferable, and 2 / g-carbon support) or more is more preferable, and 2 / g-carbon support) or more is more preferable, and 2 / g-carbon support) or more is more preferable, and 2 / g-carbon support) or more is more preferable, and 2 / g-carbon support) or more. The BET specific surface area of ​​the catalyst is, for example, 3000 (m 2 / g-carbon support) or less, and 2 / g-carbon support) or less, and 2 / g-carbon support) or less, and 2 / g-carbon support) or less, and 2 / g-carbon support) or less, and 2 / g-carbon support) or less, and 2 / g-carbon support) or less, and 2 / g-carbon support) or less. The BET specific surface area of ​​the present catalyst may be specified by any combination of any of the above-mentioned lower limit values ​​and any of the above-mentioned upper limit values.

[0055] The BET specific surface area (m 2 / g-carbon support) is the BET specific surface area (m 2 / g) and the weight ratio of the carbon support contained in the present catalyst obtained by inductively coupled plasma atomic emission spectrometry.

[0056] The catalyst preferably has an average pore diameter of 8.0 nm or less. In this case, the average pore diameter of the catalyst is, for example, more preferably 7.0 nm or less, even more preferably 6.0 nm or less, even more preferably 5.0 nm or less, even more preferably 4.5 nm or less, even more preferably 4.0 nm or less, even more preferably 3.8 nm or less, even more preferably 3.6 nm or less, even more preferably 3.4 nm or less, even more preferably 3.2 nm or less, even more preferably 3.0 nm or less, even more preferably 2.9 nm or less, even more preferably 2.8 nm or less, even more preferably 2.7 nm or less, even more preferably 2.6 nm or less, and particularly preferably 2.5 nm or less.

[0057] The average pore diameter of the present catalyst may be, for example, 1.0 nm or more, preferably 1.2 nm or more, more preferably 1.4 nm or more, even more preferably 1.6 nm or more, and particularly preferably 1.8 nm or more. The average pore diameter of the present catalyst may be specified by any combination of any of the above-mentioned lower limit values ​​and any of the above-mentioned upper limit values. The average pore diameter of the present catalyst is obtained by the BJH method from the nitrogen adsorption isotherm of the present catalyst at a temperature of 77 K.

[0058] If the average pore diameter of a metal-supported catalyst is too large, for example, when the metal-supported catalyst is used as an electrode catalyst for a fuel cell, the ionomer tends to penetrate into the pores of the metal-supported catalyst, and as a result, the catalytic metal particles supported in the pores are coated with the ionomer, which tends to reduce catalytic activity. In contrast, a porous structure having an average pore diameter equal to or less than the above-mentioned upper limit makes it difficult for the ionomer to penetrate into the pores, which contributes to improving durability and / or catalytic function.

[0059] Furthermore, if the average pore diameter of the metal-supported catalyst is too small, the catalytic metal particles are more likely to be supported on the outer surface of the carbon support than inside the pores, resulting in reduced durability. In contrast, a porous structure having an average pore diameter equal to or greater than the above-mentioned lower limit allows the catalytic metal particles to be effectively supported inside the pores, contributing to improved durability.

[0060] The catalyst has a volume of pores with a pore diameter of 5 nm or more and 70 nm or less (hereinafter referred to as "5-70 nm pore volume") (cm 3 / g-carbon support) (hereinafter referred to as "pore volume less than 5 nm") 3 / g-carbon support) (hereinafter referred to as "less than 5 nm / 5-70 pore volume ratio") is preferably 1.5 or more.

[0061] The less than 5 nm / 5-70 pore volume ratio of the present catalyst is, for example, more preferably 2.0 or more, even more preferably 3.0 or more, even more preferably 4.0 or more, even more preferably 5.0 or more, even more preferably 6.0 or more, even more preferably 7.0 or more, even more preferably 8.0 or more, even more preferably 9.0 or more, even more preferably 10.0 or more, even more preferably 11.0 or more, even more preferably 12.0 or more, even more preferably 13.0 or more, even more preferably 14.0 or more, even more preferably 15.0 or more, even more preferably 16.0 or more, even more preferably 17.0 or more, even more preferably 18.0 or more, even more preferably 19.0 or more, and particularly preferably 20.0 or more.

[0062] The <5 nm / 5-70 pore volume ratio of the present catalyst may be, for example, 50.0 or less, preferably 45.0 or less, more preferably 40.0 or less, even more preferably 35.0 or less, still more preferably 30.0 or less, still more preferably 25.0 or less, and particularly preferably 23.0 or less. The <5 nm / 5-70 pore volume ratio of the present catalyst may be specified by any combination of any of the above-mentioned lower limit values ​​and any of the above-mentioned upper limit values.

[0063] The 5-70 nm pore volume (cm) used to calculate the <5 nm / 5-70 pore volume ratio of this catalyst 3 / g-carbon support) and less than 5 nm pore volume (cm 3 / g-carbon support) is the 5-70 nm pore volume (cm) of this catalyst obtained by the BJH method from the nitrogen adsorption isotherm at 77 K. 3 / g) and less than 5 nm pore volume (cm 3 / g) and the weight ratio of the carbon support contained in the present catalyst obtained by inductively coupled plasma atomic emission spectrometry.

[0064] If the <5 nm / 5-70 pore volume ratio of a metal-supported catalyst is too small (i.e., the 5-70 nm pore volume is too large compared to the <5 nm pore volume), when the metal-supported catalyst is used as an electrode catalyst in a fuel cell, for example, generated water is likely to enter the pores, resulting in deterioration due to oxidation of the catalytic metal particles supported in the pores. In contrast, a porous structure having a <5 nm / 5-70 pore volume ratio equal to or greater than the above-mentioned lower limit makes the catalytic metal particles supported in the pores less susceptible to deterioration, thereby contributing to improved durability and / or performance of the metal-supported catalyst.

[0065] Furthermore, if the <5 nm / 5-70 pore volume ratio of a metal-supported catalyst is too large (i.e., the <5 nm pore volume is too large compared to the 5-70 nm pore volume), when the metal-supported catalyst is used as an electrode catalyst for a fuel cell, for example, the diffusibility of substances within the pores is low, which tends to result in a decrease in output characteristics. In contrast, a porous structure having a <5 nm / 5-70 pore volume ratio below the above-mentioned upper limit improves the diffusibility of substances, thereby contributing to improved output characteristics.

[0066] In the present catalyst, the ratio of the weight of the precious metal contained in the catalyst (more specifically, the precious metal contained in the catalytic metal particles) to the weight of the catalyst (hereinafter referred to as the "precious metal content") is preferably 30 wt% or more. The precious metal content of the present catalyst is, for example, more preferably 35 wt% or more, even more preferably 40 wt% or more, even more preferably 45 wt% or more, and particularly preferably 50 wt% or more. The precious metal content of the present catalyst may be, for example, 90 wt% or less, 80 wt% or less, 70 wt% or less, or 60 wt% or less. The precious metal content of the present catalyst may be specified by any combination of any of the above-mentioned lower limit values ​​and any of the above-mentioned upper limit values. The precious metal content of the present catalyst is obtained by inductively coupled plasma atomic emission spectroscopy.

[0067] This catalyst has an electrochemically effective specific surface area (ECSA) of 45 (m 2It is preferable that the value is equal to or greater than 1g of the precious metal contained in the catalyst.

[0068] The ECSA of the precious metal contained in the catalyst is, for example, 50(m 2 / g-precious metal) or more is more preferable, and 55 (m 2 / g-precious metal) or more is more preferable, and 60 (m 2 / g-precious metal) or more is more preferable, and 65 (m 2 / g-precious metal) or more is more preferable, and 70 (m 2 / g-precious metal) or more is more preferable, and 75 (m 2 / g-precious metal) or more is more preferable, and 80 (m 2 / g-noble metal) or more. The ECSA of the noble metal contained in the present catalyst is, for example, 200 (m 2 / g-precious metal) or less, and 180 (m 2 / g-precious metal) or less, and 160 (m 2 / g-precious metal) or less, and 140 (m 2 / g-precious metal) or less, and 120 (m 2 / g-precious metal) or less, and 2 The ECSA of the precious metal contained in the catalyst may be specified by any combination of the above-mentioned lower limit value and the above-mentioned upper limit value.

[0069] For example, when the precious metal contained in the catalytic metal particles supported on the catalyst is platinum, the ECSA (m 2 / g-precious metal) is the ECSA (m 2 / g-Pt) where the numerical unit " / g-Pt" indicates the value per gram of platinum contained in the catalyst.

[0070] The ECSA of the precious metal contained in the catalyst can be obtained by cyclic voltammetry using a rotating ring-disk electrode apparatus having a working electrode on which the catalyst is supported, with potential sweep at a sweep rate of 10 mV / sec.

[0071] This catalyst has a geometric specific surface area of ​​52 (m 2 The geometric specific surface area of ​​the precious metal contained in the catalyst is preferably 55 (m / g) or more. 2 / g-precious metal) or more is more preferable, and 60 (m 2 / g-precious metal) or more is more preferable, and 70 (m 2 / g-precious metal) or more is more preferable, and 75 (m 2 / g-precious metal) or more is more preferable, and 80 (m 2 / g-precious metal) or more is more preferable, and 85 (m 2 / g-precious metal) or more is more preferable, and 90 (m 2 / g-precious metal) or more is more preferable, and 95 (m 2 / g-precious metal) or more is more preferable, and 2 / g-precious metal) or more is more preferable, and 2 / g-precious metal) or more is more preferable, and 2 / g-precious metal) or more is more preferable, and 115 (m 2 It is particularly preferable that the geometric specific surface area of ​​the noble metal contained in the catalyst is 200 (m / g) or more. 2 / g-precious metal) or less, and 190 (m 2 / g-precious metal) or less, and 180 (m 2 / g-precious metal) or less, and 170 (m 2 / g-precious metal) or less, and 160 (m 2 / g-precious metal) or less, and 150 (m 2 / g-precious metal) or less, and 145 (m 2 / g-precious metal) or less, and 140 (m 2 / g-precious metal) or less, and 135 (m 2 / g-precious metal) or less, and 130 (m 2 / g-noble metal) or less. 2 / g-noble metal) may be specified by any combination of any of the above-mentioned lower limit values ​​and any of the above-mentioned upper limit values.

[0072] In addition, when the precious metal contained in the catalytic metal particles supported in the present catalyst is platinum, the geometric specific surface area (m 2 / g-noble metal) is the geometric specific surface area (m 2 / g‐Pt).

[0073] The geometric specific surface area of ​​the precious metal contained in the catalyst can be obtained by powder X-ray diffraction of the catalyst. Specifically, the geometric specific surface area of ​​the precious metal contained in the catalyst is obtained by peak separation of the (111) diffraction line of the precious metal that appears in the X-ray diffraction pattern obtained by powder X-ray diffraction of the catalyst, calculating the value of "6 / density / crystallite diameter × peak area ratio × precious metal atomic ratio" for each peak obtained by peak separation, and adding up the calculated values ​​for all peaks.

[0074] The present catalyst preferably has a carbon anchoring ratio calculated by the following formula (I) of 15.0% or more. JPEG0007812251000004.jpg21170

[0075] In the above formula (I), the "electrochemically effective specific surface area" and the "geometric specific surface area" respectively represent the electrochemically effective specific surface area (m 2 / g-noble metal) and geometric specific surface area (m 2 / g-precious metals).

[0076] The carbon anchoring ratio of the present catalyst is, for example, more preferably 16.0% or more, more preferably 18.0% or more, even more preferably 20.0% or more, even more preferably 21.0% or more, even more preferably 22.0% or more, even more preferably 23.0% or more, even more preferably 24.0% or more, even more preferably 25.0% or more, even more preferably 26.0% or more, even more preferably 27.0% or more, and particularly preferably 28.0% or more.

[0077] The carbon anchoring ratio of the present catalyst may be, for example, 50.0% or less, 45.0% or less, 40.0% or less, 35.0% or less, 33.0% or less, 32.0% or less, 31.0% or less, or 30.0% or less. The carbon anchoring ratio of the present catalyst may be specified by any combination of any of the above-mentioned lower limit values ​​and any of the above-mentioned upper limit values.

[0078] For example, when the catalytic metal particles supported on the carbon support in the present catalyst contain platinum as a precious metal, the carbon anchoring ratio of the present catalyst is calculated by dividing the "electrochemically effective specific surface area" and "geometric specific surface area" in the above formula (I) by the electrochemically effective specific surface area (m 2 / g-Pt) and geometric specific surface area (m 2 / g-Pt).

[0079] The carbon anchoring ratio (%) indicates the ratio of the geometric specific surface area of ​​the precious metal (e.g., platinum) contained in the catalytic metal particles supported on the carbon support to the area that does not contribute to the electrochemically effective specific surface area (ECSA) of the precious metal. Therefore, the carbon anchoring ratio (%) reflects the ratio of the surface area of ​​the catalytic metal particles supported on the carbon support that is coated with carbon (specifically, the surface area of ​​the portion that is firmly anchored (anchored) to the carbon support by being coated with carbon). Therefore, in a metal-supported catalyst having a carbon anchoring ratio equal to or greater than the above-mentioned lower limit, a portion of the catalytic metal particles is effectively anchored to the carbon support, and therefore the metal-supported catalyst has excellent durability and / or catalytic function.

[0080] On the other hand, a carbon anchoring ratio that is too large indicates that the ratio of the surface area covered with carbon to the surface area of ​​the catalytic metal particles supported on the carbon support is too large, i.e., the ratio of the surface area contributing to catalytic function to the surface area of ​​the catalytic metal particles is too small. Therefore, if the carbon anchoring ratio of a metal-supported catalyst is too large, for example, when the metal-supported catalyst is used as an electrode catalyst for a fuel cell, the output characteristics are likely to decrease. In contrast, a carbon anchoring ratio that is equal to or less than the above-mentioned upper limit indicates that the surface area functioning as a catalyst of the catalytic metal particles coated on the carbon support is large, contributing to improved output characteristics.

[0081] This catalyst has a carbon anchoring amount calculated by the following formula (II) of 5.0 m 2 / g or more is preferable. JPEG0007812251000005.jpg28170

[0082] In the above formula (II), the "precious metal content (wt%)" is the ratio (wt%) of the weight of the precious metal contained in the catalyst to the weight of the catalyst, and is obtained by inductively coupled plasma atomic emission spectrometry. The "geometric specific surface area" and the "electrochemically effective specific surface area" are the geometric specific surface areas (m 2 / g-noble metal) and electrochemically effective specific surface area (m2 / g-precious metals).

[0083] The carbon anchoring amount of this catalyst is, for example, 6.0 m 2 / g or more is more preferable, and 7.0m 2 / g or more is more preferable, and 8.0m 2 / g or more is more preferable, and 9.0m 2 / g or more is more preferable, and 10.0m 2 / g or more is more preferable, and 11.0m 2 / g or more is more preferable, and 12.0m 2 / g or more is more preferable, and 13.0m 2 / g or more is more preferable, and 14.0m 2 / g or more is more preferable, and 15.0m 2 It is particularly preferable that the saturation coefficient is 1 / g or more.

[0084] The carbon anchoring amount of the catalyst is, for example, 40.0 m 2 / g or less, and 2 / g or less, and 30.0m 2 / g or less is more preferable, and 25.0m 2 / g or less is more preferable, and 20.0m 2 / g or less is particularly preferred. The carbon anchoring amount of the present catalyst may be specified by any combination of any of the above-mentioned lower limit values ​​and any of the above-mentioned upper limit values.

[0085] For example, when the catalytic metal particles supported on the carbon support in the present catalyst contain platinum as a precious metal, the carbon anchoring amount of the present catalyst is calculated by using the "platinum content (wt%)" which is the ratio of the weight of platinum contained in the present catalyst to the weight of the present catalyst as the "precious metal content" in the above formula (II), and the "electrochemically effective specific surface area" and "geometric specific surface area" are respectively calculated by the electrochemically effective specific surface area (m 2 / g-Pt) and geometric specific surface area (m 2 / g-Pt).

[0086] Carbon anchoring amount (m 2 / g) is the surface area (m ) of the carbon-coated precious metal contained in 1 g of the metal-supported catalyst, calculated taking into account the precious metal content (wt%) of the catalytic metal particles in the metal-supported catalyst. 2 Therefore, in a metal-supported catalyst having a carbon anchoring amount equal to or greater than the above-mentioned lower limit, a portion of the catalytic metal particles is effectively fixed to the carbon support, and therefore the metal-supported catalyst has excellent durability and / or catalytic function.

[0087] On the other hand, an excessively large carbon anchoring amount indicates that the surface area of ​​the catalytic metal particles supported on the carbon support that is covered with carbon is too large, i.e., the surface area of ​​the catalytic metal particles that contributes to catalytic function is too small. Therefore, if the carbon anchoring amount of a metal-supported catalyst is too large, for example, when the metal-supported catalyst is used as an electrode catalyst for a fuel cell, the output characteristics are likely to decrease. In contrast, a carbon anchoring amount equal to or less than the above-mentioned upper limit indicates that the surface area that functions as a catalyst of the catalytic metal particles covered on the carbon support is large, and contributes to improving the output characteristics.

[0088] The catalyst preferably has a durability index calculated by the following formula (III) of 0.50 cm or more. JPEG0007812251000006.jpg21170

[0089] As mentioned above, the Raman D half-width at half maximum indicates the crystallinity of carbon around the edge portion included in the carbon structure, and the higher the degree of crystallinity of the carbon, the smaller the value becomes. Therefore, as an index of durability that takes into account the degree of crystallinity of carbon, we use a durability index calculated by multiplying the reciprocal of the Raman D half-width at half maximum by the carbon anchoring ratio.

[0090] The durability index of the present catalyst is, for example, more preferably 0.55 cm or more, even more preferably 0.60 cm or more, even more preferably 0.65 cm or more, even more preferably 0.70 cm or more, even more preferably 0.75 cm or more, even more preferably 0.80 cm or more, even more preferably 0.85 cm or more, even more preferably 0.90 cm or more, even more preferably 0.95 cm or more, even more preferably 1.00 cm or more, even more preferably 1.05 cm or more, even more preferably 1.10 cm or more, and particularly preferably 1.15 cm or more. The durability index of the present catalyst may be, for example, 5.00 cm or less, 4.50 cm or less, 4.00 cm or less, 3.50 cm or less, 3.00 cm or less, 2.50 cm or less, 2.00 cm or less, or 1.50 or less. The durability index of the present catalyst may be specified by any combination of any of the above-mentioned lower limit values ​​and any of the above-mentioned upper limit values.

[0091] The method for producing a metal-supported catalyst according to this embodiment (hereinafter referred to as "this method") includes an impregnation step of impregnating a carbon support with a precursor of the metal that constitutes the catalytic metal particles, a reduction treatment step of reducing the metal precursor impregnated in the carbon support to obtain a metal-supported catalyst carrying particles of the metal, and a heat treatment step of heat treating the metal-supported catalyst.

[0092] In the impregnation step, the carbon support is impregnated with a precursor of the metal that constitutes the catalytic metal particles. That is, for example, when catalytic metal particles containing a pure precious metal are supported, the carbon support is impregnated with a precursor of the precious metal. On the other hand, when catalytic metal particles containing a precious metal alloy are supported, the carbon support is impregnated with a precursor of the precious metal and a precursor of a non-precious metal that constitute the precious metal alloy.

[0093] In the reduction treatment step, the carbon support impregnated with the metal precursor in the impregnation step is subjected to reduction treatment to obtain a metal-supported catalyst containing the carbon support and particles of the metal supported on the carbon support. The reduction treatment may be a liquid-phase reduction treatment or a gas-phase reduction treatment, but is preferably a gas-phase reduction treatment.

[0094] In the heat treatment step, the metal-supported catalyst obtained in the reduction treatment step is subjected to a heat treatment so that the individual catalytic metal particles are partially coated with carbon contained in the carbon support of the metal-supported catalyst.

[0095] The atmosphere in which the heat treatment is performed is not particularly limited as long as the effects of the present invention can be obtained, but it is preferable to perform the heat treatment in an atmosphere containing an inert gas (e.g., one or more selected from the group consisting of nitrogen gas, argon gas, helium gas, and neon gas), or in a vacuum.

[0096] The concentration of the inert gas in the atmosphere in which the heat treatment is performed is not particularly limited as long as the effects of the present invention are obtained, but for example, it is preferably 50% by volume or more, more preferably 60% by volume or more, even more preferably 70% by volume or more, even more preferably 80% by volume or more, even more preferably 90% by volume or more, and particularly preferably 100% by volume.

[0097] The temperature at which the metal-supported catalyst is heated in the heat treatment (heat treatment temperature) is not particularly limited as long as the effects of the present invention are obtained, but is, for example, preferably 600°C or higher, more preferably 650°C or higher, even more preferably 700°C or higher, even more preferably 750°C or higher, and particularly preferably 800°C or higher. The heat treatment temperature may be, for example, 1300°C or lower, preferably 1100°C or lower, more preferably 1000°C or lower, and particularly preferably 900°C or lower. The heat treatment temperature may be specified by any combination of any of the above-mentioned lower limit values ​​and any of the above-mentioned upper limit values.

[0098] The time for heating the metal-supported catalyst at the heat treatment temperature (heat treatment time) is not particularly limited as long as the effects of the present invention are obtained, but is, for example, preferably 5 minutes or more, more preferably 10 minutes or more, even more preferably 20 minutes or more, even more preferably 30 minutes or more, even more preferably 40 minutes or more, even more preferably 60 minutes or more, even more preferably 80 minutes or more, and particularly preferably 100 minutes or more. Furthermore, the heat treatment time may be, for example, 24 hours or less, preferably 12 hours or less, more preferably 6 hours or less, even more preferably 180 minutes or less, and particularly preferably 150 minutes or less. The heat treatment time may be specified by any combination of any of the above-mentioned lower limit values ​​and any of the above-mentioned upper limit values.

[0099] According to the present method, a metal-supported catalyst having both excellent durability and excellent catalytic function can be produced. That is, the present catalyst described above is preferably produced by the present method.

[0100] The electrode according to this embodiment (hereinafter referred to as "the electrode") contains the catalyst. That is, the electrode is, for example, a battery electrode containing an electrode substrate and the catalyst supported on the electrode substrate. The electrode is preferably a battery electrode. That is, the electrode is preferably an electrode of, for example, a fuel cell (e.g., a polymer electrolyte fuel cell), an air cell, a water electrolyzer (e.g., a polymer electrolyte water electrolyzer), a redox flow battery, or a halogen battery.

[0101] The electrode may be either a cathode or an anode, but is preferably a cathode, i.e., the electrode is the cathode or anode, preferably a cathode, of a fuel cell, air cell, water electrolyzer, redox flow battery, or halogen battery.

[0102] The battery according to this embodiment (hereinafter referred to as "this battery") includes this electrode. Specifically, this battery is preferably a fuel cell (e.g., a polymer electrolyte fuel cell), an air battery, a redox flow battery, or a halogen battery that includes this electrode. This battery preferably has a membrane electrode assembly (MEA) that includes this electrode.

[0103] The present battery is a battery having the present electrode as a cathode or an anode, preferably a battery having the present electrode as a cathode. That is, the present battery is a fuel cell, air battery, redox flow battery, or halogen battery having the present electrode as a cathode or an anode, preferably a fuel cell, air battery, redox flow battery, or halogen battery having the present electrode as a cathode.

[0104] Next, a specific example according to this embodiment will be described. [Example]

[0105] [Manufacturing of carbon supports] 1.0 g of polyacrylonitrile (PAN), 1.0 g of 2-methylimidazole, 6.0 g of zinc chloride (ZnCl), and 30 g of dimethylformamide were mixed. The resulting mixture was dried to remove the solvent. The dried mixture was heated in an air atmosphere to 250°C for infusibility.

[0106] The infusibilized mixture was heated to 1500°C under a gauge pressure of 0.90 MPa in a nitrogen atmosphere to carbonize it. Dilute hydrochloric acid was added to the carbonized material obtained by carbonization and stirred. The suspension containing the carbonized material was then filtered using a filter membrane, and the carbonized material was washed with distilled water until the filtrate became neutral. In this way, metal removal treatment by acid washing was performed.

[0107] The carbonized material after the metal removal treatment was pulverized using a fine grinder until the median particle size was 0.4 μm or less. The pulverized carbonized material was vacuum dried to remove moisture. The carbonized material was then subjected to a heat treatment at 300°C in a nitrogen atmosphere. The carbonized material obtained in this manner was used as the carbon support C1500.

[0108] Further, a carbonized material obtained in the same manner as in the case of the carbon support C1500, except that the carbonization temperature was changed from 1500°C to 2000°C, was used as the carbon support C2000.

[0109] Furthermore, the carbon support C1500 was graphitized by heating it in a nitrogen atmosphere under normal pressure at 1800°C, 2000°C, 2100°C, or 2400°C. The carbonized materials obtained by the graphitization treatments at 1800°C, 2000°C, 2100°C, and 2400°C were used as carbon supports C1500-G1800, C1500-G2000, C1500-G2100, and C1500-G2400, respectively.

[0110] Commercially available Ketjenblack (EC600JD, manufactured by Lion Specialty Chemicals Co., Ltd.) was used as the carbon support KB. The carbon support KB was graphitized by heating it at 2000°C under atmospheric pressure in a nitrogen atmosphere. The carbon material obtained by this graphitization process was used as the carbon support KB-G2000.

[0111] [Production of metal-supported catalysts] In Examples 1, 3 to 6, C2, C4, and C5, platinum particles were supported on a carbon support by the following vapor-phase reduction method. First, an impregnation step was performed. Specifically, 1 g of the carbon support and 20 g of an aqueous solution containing chloroplatinic acid (HPtCl), a platinum precursor, in an amount sufficient to achieve a platinum concentration of 5 wt % (platinum content per gram) were mixed and stirred for 1 hour. The mixed solution was first maintained under a reduced pressure of −0.10 MPa or less (specifically, −0.10 MPa to −0.1013 MPa) for 1 hour, then maintained under an increased pressure of 0.15 MPa or more (specifically, 0.15 MPa to 0.20 MPa) for 1 hour, and then stirred and mixed for 66 hours. This impregnation step was performed while maintaining the temperature of the mixed solution at 5°C or less (specifically, 0°C to 5°C).

[0112] Next, a reduction step was carried out. The mixture obtained in the impregnation step was dried under vacuum at 100°C and then maintained at 150°C in a nitrogen atmosphere to volatilize the solvent component. The resulting solid was then subjected to a heat treatment (gas-phase reduction treatment) at 350°C for 120 minutes in a hydrogen atmosphere (100% by volume of hydrogen gas).

[0113] A heat treatment step was then carried out. Specifically, the solid obtained in the reduction step was heat-treated at 825°C for 120 minutes in a nitrogen atmosphere. In this way, a metal-supported catalyst was obtained, which included a carbon support (carbon support C1500 in Example 1, carbon support C1500-G1800 in Example 3, carbon support C1500-G2000 in Example 4, carbon support C1500-G2100 in Example 5, carbon support C2000 in Example 6, carbon support C1500-G2400 in Example C2, carbon support KB in Example C4, and carbon support KB-G2000 in Example C5) and platinum particles supported on the carbon support.

[0114] In Example 2, a metal-supported catalyst containing carbon support C1500 and platinum particles supported on the carbon support was obtained in the same manner as in the above-mentioned Example 1, etc., except that in the impregnation step, the mixed solution was held under normal pressure for 2 hours instead of being held under vacuum and pressure, and the heat treatment time in the heat treatment step was 40 minutes instead of 120 minutes.

[0115] In Example 7, a metal-supported catalyst containing carbon support C1500-G2000 and platinum particles supported on the carbon support was obtained in the same manner as in Example 1 above, except that the heat treatment time in the heat treatment step was 40 minutes instead of 120 minutes.

[0116] In Example 8, a metal-supported catalyst containing carbon support C2000 and platinum particles supported on the carbon support was obtained in the same manner as in the above-mentioned Example 1, etc., except that in the impregnation step, the mixed solution was held under normal pressure for 2 hours instead of being held under vacuum and pressure.

[0117] In Example 9, platinum alloy particles were supported on a carbon support by the following vapor-phase reduction method. First, a first impregnation step was performed. 1 g of the carbon support and 14 g of an aqueous solution containing chloroplatinic acid (HPtCl) in an amount sufficient to give a platinum concentration of 5 wt % (platinum content: 0.70 g) were mixed and stirred for 1 hour. The mixed solution was first maintained under a reduced pressure of −0.10 MPa or less (specifically, −0.10 MPa to −0.1013 MPa) for 1 hour, then maintained under an increased pressure of 0.15 MPa or more (specifically, 0.15 MPa to 0.20 MPa) for 1 hour, and then stirred and mixed for 66 hours. This first impregnation step was performed while maintaining the temperature of the mixed solution at 5°C or less (specifically, 0°C to 5°C).

[0118] Next, a first gas-phase reduction step was carried out. That is, the mixed solution obtained in the first impregnation step was dried under vacuum at 100°C, and then the solvent component was volatilized by maintaining it in a nitrogen atmosphere at 150°C. The obtained solid was subjected to a heat treatment (first gas-phase reduction treatment) at 350°C for 120 minutes in a hydrogen atmosphere (100% by volume of hydrogen gas) to obtain a platinum-supported catalyst.

[0119] Next, the second impregnation step was carried out. 1.7 g of the platinum-supported catalyst obtained in the first gas-phase reduction step was mixed with 20 g of an aqueous solution containing cobalt chloride (CoCl2), a cobalt precursor, in an amount sufficient to give a cobalt concentration of 0.21 wt% (cobalt content: 0.042 g), and the mixture was stirred for 18 hours. The mixture was first maintained under reduced pressure of -0.10 MPa or less (specifically, -0.10 MPa to -0.1013 MPa) for 1 hour, then maintained under increased pressure of 0.15 MPa or more (specifically, 0.15 MPa to 0.20 MPa) for 1 hour, and then stirred and mixed for 18 hours. This second impregnation step was carried out while maintaining the temperature of the mixture at 5°C or less (specifically, 0°C to 5°C).

[0120] Next, a second gas-phase reduction step and a heat treatment step were carried out consecutively. That is, the mixed liquid obtained in the second impregnation step was dried under vacuum at 100°C. The obtained solid was subjected to a heat treatment (second gas-phase reduction treatment) at 700°C for 60 minutes in a hydrogen atmosphere (100% by volume of hydrogen gas). Subsequently, while maintaining the temperature of the atmosphere in the range of 650 to 750°C, the hydrogen atmosphere was replaced with a nitrogen atmosphere (100% by volume of nitrogen gas), and a heat treatment was carried out in the nitrogen atmosphere at 700°C for 120 minutes to obtain a platinum alloy supported catalyst.

[0121] Next, a post-treatment step was carried out. Specifically, in order to remove excess metal from the platinum alloy-supported catalyst obtained in the heat treatment step, the platinum alloy-supported catalyst was mixed with a 10% nitric acid solution for 2 hours. The platinum alloy-supported catalyst was then separated from the acid solution by filtration, and the platinum alloy-supported catalyst was further washed with distilled water until the filtrate became neutral. The washed platinum alloy-supported catalyst was dried under vacuum at 60°C to remove moisture.

[0122] Thereafter, the platinum alloy-supported catalyst was subjected to a heat treatment at 300°C in a nitrogen atmosphere to remove nitric acid. Furthermore, the platinum alloy-supported catalyst was subjected to a heat treatment at 700°C in a nitrogen atmosphere to reduce and remove platinum oxide. In this way, a metal-supported catalyst was obtained, which included the carbon support C1500-G1800 and platinum-cobalt alloy particles supported on the carbon support.

[0123] In Example C1, a metal-supported catalyst containing carbon support C1500 and platinum particles supported on the carbon support was obtained in the same manner as in Example 1 above, except that the heat treatment temperature in the heat treatment step was 600°C instead of 825°C.

[0124] In Example C3, platinum particles were supported on a carbon support by the following liquid-phase reduction method: First, an impregnation step was carried out: 1 g of the carbon support was mixed with 22.2 g of an aqueous solution containing chloroplatinic acid (HPtCl) in an amount sufficient to give a platinum concentration of 5 wt % (platinum content of 1.1 g) and stirred for 66 hours.

[0125] Next, a liquid-phase reduction step was carried out. That is, ethylene glycol was added as a reducing agent to the mixed solution obtained in the impregnation step, and the mixture was held in an air atmosphere at 80°C for 4 hours to carry out a liquid-phase reduction treatment, thereby obtaining a platinum-supported catalyst. The resulting mixed solution was then dried at 100°C under vacuum and further held at 150°C in a nitrogen atmosphere to volatilize the solvent components. In this way, a metal-supported catalyst containing carbon support C1500-G1800 and platinum particles supported on the carbon support was obtained.

[0126] In Example C6, a commercially available platinum-supported catalyst Pt / C-1 containing a non-porous solid carbon support and platinum particles supported on the carbon support was used as the metal-supported catalyst.

[0127] In Example C7, a commercially available platinum-supported catalyst Pt / C-2 containing Ketjen black and platinum particles supported on the Ketjen black was used as the metal-supported catalyst.

[0128] [Raman spectroscopy] The metal-supported catalysts were analyzed by Raman spectroscopy. Raman spectra were measured using a HORIBA microscopic laser Raman spectrometer (LabRAM, HORIBA Jobin Yvon). The laser used for the measurements had an excitation wavelength of 532 nm, an output of 50 mW, and was measured through a neutral density filter D3 under the conditions of 90 seconds of exposure x 2 accumulations.

[0129] The Raman spectra were subjected to baseline correction. -1 ) is 600cm -1 Scattering intensity near 2000cm -1 A straight line connecting nearby scattering intensities was determined as the baseline, and baseline correction was performed by subtracting this baseline from each intensity of the scattering spectrum.

[0130] Then the Raman shift is 1340cm -1 Around (specifically, 1320 cm -1 Above, 1360cm -1 The D band with a peak top in the range of 1000 to 15000 was identified. d (D band peak top intensity) -1 )A d From the above, the intensity of the D band I d The Raman shift (cm) corresponding to half the intensity of -1 )B d By subtracting the Raman D half-width at half maximum (cm -1 That is, the Raman D half width at half maximum of the metal-supported catalyst was calculated by the following formula: Raman D half width at half maximum (cm -1 )=A d (cm -1 )-B d (cm -1 ).

[0131] Here, FIG. 1 shows, as an example of a Raman spectrum, the results of analyzing the Raman spectrum obtained by Raman spectroscopy of the metal-supported catalyst of Example 1. In FIG. 1, the horizontal axis represents the Raman shift (cm -1 ) and the vertical axis indicates the scattering intensity after baseline correction. d is the Raman shift (cm) corresponding to the peak top of the D band -1 ) and B d is the A d D band intensity I at lower wavenumbers d The Raman shift (cm) corresponding to the Raman spectrum showing half the intensity (height of the peak top of the D band) -1) is shown.

[0132] [Metal content: Inductively coupled plasma atomic emission spectroscopy] The platinum and non-platinum metal (metals other than platinum) contents of the metal-supported catalyst were measured by inductively coupled plasma optical emission spectroscopy (ICP-OES). First, 100 mg of the metal-supported catalyst was heated at 800°C for 3 hours in an air atmosphere to remove non-metallic components (components other than metals) from the metal-supported catalyst.

[0133] The metal-supported catalyst was then immersed in 5 mL of aqua regia and heated at 50°C for 1 hour to dissolve the metals contained in the metal-supported catalyst. Distilled water was then added to dilute the solution to a volume of 50 mL, yielding a metal solution. The platinum and non-platinum metal concentrations of the resulting metal solution were then measured using a sequential plasma emission spectrometer (ICPS-8100, manufactured by Shimadzu Corporation).

[0134] The platinum concentration (mg / mL) and non-platinum metal concentration (mg / mL) of the metal solution were multiplied by the volume of the metal solution (50 mL) to obtain the platinum content (mg) and non-platinum metal content (mg) per 100 mg of metal-supported catalyst.

[0135] Furthermore, the platinum content (wt%) and non-platinum metal content (wt%) obtained by ICP-OES were calculated by dividing the platinum weight (mg) and non-platinum metal weight (mg) contained in the metal-supported catalyst by 100 mg, which is the weight of the metal-supported catalyst, and then multiplying this result by 100. The sum of the platinum content (wt%) and non-platinum metal content (wt%) of the metal-supported catalyst was also calculated as the metal content (wt%) of the metal-supported catalyst.

[0136] [Specific surface area, average pore diameter and total pore volume] The specific surface area, average pore diameter, and total pore volume of the metal-supported catalyst were measured by nitrogen adsorption using a specific surface area / pore size distribution analyzer (TriStar II 3020, manufactured by Shimadzu Corporation) and the accompanying analysis software (TriStar II 3020).

[0137] First, 0.1 g of the metal-supported catalyst was heated at 100°C for 6.7 × 10 -2 The water adsorbed on the metal-supported catalyst was removed by holding the catalyst at 77 Pa for 3 hours. Next, the change in the amount of nitrogen adsorbed on the metal-supported catalyst with the change in nitrogen gas pressure was measured at a temperature of 77 K, and a nitrogen adsorption isotherm at a temperature of 77 K was obtained.

[0138] The nitrogen adsorption isotherm at 77 K was used to calculate the BET specific surface area (m 2 / g) was obtained. Furthermore, the BET specific surface area (m 2 / g) and the metal content (wt%) of the metal-supported catalyst obtained by ICP-OES described above, the BET specific surface area (m 2 / g-carbon support). That is, the weight ratio of the carbon support contained in the metal-supported catalyst was first calculated using the following formula: Weight ratio of carbon support = 1 - (metal content (wt%) obtained by ICP-OES) / 100. Next, the BET specific surface area (m 2 / g), the BET specific surface area per 1 g of carbon support (m 2 / g carbon support) was calculated.

[0139] In addition, from the nitrogen adsorption isotherm at a temperature of 77 K, the volume of pores with diameters of 5 nm or more and 70 nm or less (5-70 nm pore volume) (cm 3 / g) and the volume of pores with a diameter of less than 5 nm (<5 nm pore volume) (cm 3 / g) was obtained.

[0140] Similarly to the BET specific surface area described above, the 5-70 nm pore volume (cm) per 1 g of carbon support contained in the metal-supported catalyst was calculated based on the metal content of the metal-supported catalyst obtained by ICP-OES. 3 / g-carbon support) and less than 5 nm pore volume (cm 3 / g carbon support) was calculated.

[0141] Furthermore, the pore volume (cm) of less than 5 nm 3 / g-carbon support) 5-70 nm pore volume (cm 3 / g-carbon support), the 5-70 nm pore volume (cm 3 / g-carbon support) 3 The ratio (<5 nm / 5-70 nm pore volume ratio) of the carbon support was calculated.

[0142] In addition, the total pore volume (cm) of the metal-supported catalyst was calculated from the amount of adsorption at the point where the relative pressure P / P0 was 0.98 in the nitrogen adsorption isotherm at 77 K. 3 The average pore diameter (nm) of the metal-supported catalyst was calculated using the analysis software attached to the specific surface area and pore size distribution analyzer according to the following formula: average pore diameter (nm) = 4 × {total pore volume (cm 3 / g)×10 21} / {specific surface area(m 2 / g)×10 18}.

[0143] [Electrochemically effective specific surface area (ECSA)] The electrochemically effective specific surface area (ECSA) (m 2 / g‐Pt) was evaluated by the rotating ring‐disk electrode method using a rotating ring‐disk electrode apparatus (RRDE‐3A rotating ring‐disk electrode apparatus ver. 1.2, manufactured by BAS Co., Ltd.) and a dual electrochemical analyzer (CHI700C, manufactured by ALS Co., Ltd.).

[0144] That is, first, a three-electrode rotating ring-disk electrode device having a working electrode containing a metal-supported catalyst was fabricated. Specifically, 5 mg of the metal-supported catalyst, 50 μL of 5% Nafion (registered trademark) (manufactured by Sigma-Aldrich, Nafion perfluorinated ion exchange resin, 5% solution (product number: 510211)), 400 μL of water, and 100 μL of isopropyl alcohol were mixed to prepare a slurry. Next, this slurry was subjected to ultrasonic treatment for 10 minutes, and then to homogenization for 2 minutes. The obtained slurry was then subjected to a 10-minute ultrasonic treatment with a metal-supported catalyst coating amount of 0.1 mg / cm.2 The solution was applied to a working electrode (RRDE-3A ring-disk electrode, platinum ring-gold disk electrode, disk diameter 4 mm, manufactured by BAS Inc.) so that the solution satisfies the above formula, and then dried to prepare a working electrode supported with the metal-supported catalyst.

[0145] A platinum electrode (Pt counter electrode 23 cm, manufactured by BAS Co., Ltd.) was used as the counter electrode, and a reversible hydrogen electrode (RHE) (reservoir-type reversible hydrogen electrode, manufactured by EC Frontier Co., Ltd.) was used as the reference electrode. In this way, a rotating ring-disk electrode device was obtained, which had a working electrode containing a metal-supported catalyst, a platinum electrode as the counter electrode, and a reversible hydrogen electrode (RHE) as the reference electrode. A 0.1 M aqueous solution of perchloric acid was used as the electrolyte.

[0146] The ECSA was measured using the rotating ring-disk electrode apparatus described above. Specifically, cyclic voltammetry (CV) was performed in a nitrogen atmosphere using a three-electrode rotating ring-disk electrode apparatus having a working electrode containing a metal-supported catalyst.

[0147] For CV, oxygen was removed from the electrolyte by bubbling nitrogen for 10 min, and then the potential was swept from 0.0 V (vs. NHE) to 0.94 V (vs. NHE) at a sweep rate of 10 mV / sec. The current density was recorded as a function of potential.

[0148] From the cyclic voltammogram thus obtained, ECSA(m 2 Specifically, in the cyclic voltammogram of the third cycle, the hydrogen adsorption charge (Q Hupd )(mC / cm 2 ) to obtain the area converted electrical charge (210 μC / cm 2 ) and platinum coating amount (L Pt )(mg-Pt / cm 2 ) was used to obtain ECSA according to the following formula (IV). JPEG0007812251000007.jpg17170

[0149] [Geometric specific surface area: powder X-ray diffraction method] The geometric specific surface area (m 2 / g-Pt) was measured. That is, first, a powdered metal-supported catalyst sample was placed in a recess (2 cm × 2 cm × 0.5 mm thick) of a glass sample plate and pressed down with a slide glass, and the sample was uniformly packed in the recess so that its surface coincided with the reference plane. Next, the glass sample plate was fixed to a wide-angle X-ray diffraction sample stage so that the shape of the packed sample would not be distorted.

[0150] Powder X-ray diffraction measurements were then performed using an X-ray diffractometer (Rigaku RINT2100 / PC, Rigaku Corporation). The voltage and current applied to the X-ray tube were 50 kV and 300 mA, respectively. The sampling interval was 0.1°, the scanning speed was 1° / min, and the measurement angle range (2θ) was 5 to 90°. CuKα was used as the incident X-ray. The sample thickness was 0.5 mm, and the divergence slit width β was 2 / 3°.

[0151] The resulting XRD pattern was subjected to peak separation using a Gaussian function, as described below, and the crystallite diameter corresponding to each peak obtained by the peak separation was determined using the Scherrer equation. The value of "6 / density / crystallite diameter x peak area ratio x platinum atom ratio" was calculated for each peak, and the geometric specific surface area of ​​platinum contained in the metal-supported catalyst was calculated by adding up the values ​​for all peaks.

[0152] For example, in the case of a metal-supported catalyst carrying catalytic metal particles containing platinum, the (111) diffraction line of platinum appears at a diffraction angle (2θ) of about 40° (for example, within a range of 35° to 44°) in the XRD pattern obtained by powder X-ray diffraction using CuKα radiation. This diffraction line includes diffraction lines originating from pure platinum, diffraction lines originating from platinum alloys, and diffraction lines originating from the carbon structure of the carbon support.

[0153] Diffraction lines originating from pure platinum are defined as those having a peak top at a diffraction angle (2θ) of 39.6° or more and less than 39.8°. Diffraction lines originating from platinum alloys are defined as those having a peak top at a diffraction angle (2θ) of 39.9° or more and less than 43.0°. Diffraction lines originating from the carbon structure of the carbon support are defined as those having a peak top at a diffraction angle (2θ) of 43.3° or more and less than 43.7°.

[0154] When a metal-supported catalyst contains multiple types of platinum alloys with different compositions and / or crystal structures, multiple diffraction lines originating from the platinum alloys appear. The diffraction angles at which the peak tops of the diffraction lines originating from the platinum alloys are located are determined by their compositions and crystal structures.

[0155] For example, the composition Pt X The diffraction lines originating from platinum-cobalt alloys represented by Co (X=1 to 20) are defined as diffraction lines having a peak top at a diffraction angle of 39.9° or more and less than 41.8°. X The diffraction lines originating from platinum-nickel alloys represented by Ni (X=1 to 20) are defined as diffraction lines having a peak top at a diffraction angle of 39.9° or more and less than 42.0°. X The diffraction lines derived from a platinum-nickel-manganese alloy represented by Ni1Mn1 (X=2 to 40) are defined as diffraction lines having a peak top at a diffraction angle of 39.9° or more and less than 41.2°.

[0156] Specifically, for example, a diffraction line derived from a platinum-cobalt alloy with a composition of PtCo is defined as a diffraction line having a peak top at a diffraction angle of 41.1° or more and less than 41.5°. A diffraction line derived from a platinum-cobalt alloy with a composition of PtCo is defined as a diffraction line having a peak top at a diffraction angle of 40.1° or more and less than 40.5°. A diffraction line derived from a platinum-cobalt alloy with a composition of PtCo is defined as a diffraction line having a peak top at a diffraction angle of 39.9° or more and less than 40.1°.

[0157] For example, a diffraction line derived from a platinum-nickel alloy with a composition of PtNi is defined as a diffraction line having a peak top at a diffraction angle of 41.6° or more and less than 42.0°. A diffraction line derived from a platinum-nickel alloy with a composition of PtNi is defined as a diffraction line having a peak top at a diffraction angle of 40.4° or more and less than 41.2°. A diffraction line derived from a platinum-nickel alloy with a composition of PtNi is defined as a diffraction line having a peak top at a diffraction angle of 39.9° or more and less than 40.3°. A diffraction line derived from a platinum-nickel-manganese alloy with a composition of PtNiMn is defined as a diffraction line having a peak top at a diffraction angle of 40.1° or more and less than 40.8°.

[0158] Furthermore, when the metal-supported catalyst contains multiple types of platinum particles that have the same composition and crystal structure but different crystallite sizes, multiple diffraction lines appear that have peak tops at approximately the same diffraction angle and different full widths at half maximum.

[0159] In fact, in the XRD pattern obtained for the metal-supported catalyst, the platinum (111) diffraction line appeared at a diffraction angle (2θ) of approximately 40°. Therefore, baseline correction was first performed. That is, the line connecting the diffraction intensity at a diffraction angle (2θ) of 30° and the diffraction intensity at a diffraction angle (2θ) of 50° was determined as the baseline, and baseline correction was performed by subtracting this baseline from the intensity of each diffraction line.

[0160] Next, the baseline-corrected diffraction lines were separated into peaks derived from one or more types of pure Pt and / or one or more types of Pt alloys, and a peak derived from carbon. The separation of the diffraction lines was performed by assuming that each of the multiple peaks obtained by the separation was represented by a Gaussian function, and optimizing the intensity of the Gaussian function for each of the multiple peaks, the diffraction angle at the peak top, and the full width at half maximum, so as to minimize the sum of squares of the residuals obtained by adding up the squares of the differences (residuals) between the intensity of the diffraction line and the sum of the intensities of each of the multiple peaks at each diffraction angle in the XRD pattern.

[0161] Here, with reference to the XRD pattern obtained by powder XRD measurement of the metal-supported catalyst of Example 1, the peak separation of the (111) diffraction line of platinum, which has a peak top at a diffraction angle (2θ) of around 40° (within the range of 39° to 44°), will be described.

[0162] In the XRD pattern of the metal-supported catalyst of Example 1, after baseline correction, a diffraction line with a peak top at a diffraction angle (2θ) of approximately 40° (specifically, 39.5° or more and 40.5° or less) appeared, as shown in FIG. 2A. The shape of the middle part of this diffraction line was significantly narrower than the shape of the lower part. Therefore, at a diffraction angle (2θ) of approximately 40°, it was thought that at least two diffraction lines overlapped, including a diffraction line of the first platinum with a relatively large full width at half maximum and a diffraction line of the second platinum with a different crystallite diameter from the first platinum and a smaller full width at half maximum. Furthermore, because the metal-supported catalyst contained a carbon support, it was thought that a diffraction line derived from carbon was also present at a diffraction angle (2θ) of approximately 43.5°.

[0163] Therefore, using the peak separation method described above, the diffraction line having a peak top at a diffraction angle (2θ) of approximately 40° was separated into three components consisting of a peak derived from the first platinum, a peak derived from the second platinum, and a peak derived from carbon.

[0164] The results of this peak separation into three components are shown in Figure 2A. In Figure 2A, the "baseline-corrected" diffraction lines indicate the diffraction lines obtained by applying baseline correction to the diffraction lines obtained by XRD measurement, and the "Pt1" peak, the "Pt2" peak, and the "Carbon" peak indicate the peaks derived from the first platinum, the second platinum, and the carbon, respectively, obtained by peak separation of the "baseline-corrected" diffraction lines. Furthermore, the "Pt1 + Pt2 + Carbon" peak indicates the peak obtained by adding the "Pt1" peak, the "Pt2" peak, and the "Carbon" peak.

[0165] However, as shown in Figure 2A, when the baseline-corrected diffraction line peak separation was performed so that the broadening of the base from the diffraction angle (2θ) around 34° to 38° and the intensity of the peak top around 39.7° matched, the shoulders around 39° and 41° could not be reproduced.

[0166] In this regard, as described above, the diffraction line derived from pure platinum has a peak top at a position equal to or greater than 39.6° and less than 39.8°, and therefore it was thought that a third diffraction line of platinum having a peak top at a position around 39.7° was further mixed in.

[0167] Therefore, the diffraction line at a diffraction angle (2θ) of around 39.7° was separated into four components consisting of a peak derived from the first platinum, a peak derived from the second platinum, a peak derived from the third platinum, and a peak derived from carbon.

[0168] The results of this peak separation into four components are shown in Figure 2B. In Figure 2B, the "baseline corrected" diffraction lines indicate diffraction lines obtained by applying baseline correction to the diffraction lines obtained by XRD measurement, and the "Pt1" peak, the "Pt2" peak, the "Pt3" peak, and the "Carbon" peak indicate the peaks derived from the first platinum, the second platinum, the third platinum, and the carbon, respectively, obtained by peak separation of the "baseline corrected" diffraction lines.

[0169] The peak obtained by adding the "Pt1," "Pt2," "Pt3," and "Carbon" peaks is not shown in Figure 2B because it almost perfectly matched the "baseline-corrected" diffraction line.

[0170] Thus, the sum of squares of residuals when the peaks were separated into four components was reduced to an extremely small value compared to the sum of squares of residuals when the peaks were separated into three components. Therefore, it was concluded that the metal-supported catalyst of Example 1 supported first platinum particles, second platinum particles, and third platinum particles as Pt particles.

[0171] The crystallite diameter of each of the first platinum particles, the second platinum particles, and the third platinum particles was calculated using the following Scherrer equation: Crystallite diameter (nm) = Kλ / βcosθ, where K is the Scherrer constant (0.94), λ is the wavelength of CuKα radiation (0.15418 nm), β is the full width at half maximum (radian), and θ is the diffraction angle (radian).

[0172] That is, for example, the crystallite diameter of the first platinum particles was calculated by substituting the diffraction angle and full width at half maximum of the "Pt1" separation peak in the XRD pattern shown in FIG. 2B into the Scherrer formula. As a result, the crystallite diameter of the first platinum particles was calculated to be 1.10 × 10 ―9 m, and the crystallite diameter of the second platinum particle was calculated to be 3.52 × 10 ―9 m, and the crystallite diameter of the third platinum particle was calculated to be 15.3 × 10 ―9 It was calculated as m.

[0173] Furthermore, the area of ​​each of the three Pt separation peaks obtained by the above-mentioned peak separation (i.e., the peak area of ​​"Pt1", the peak area of ​​"Pt2", and the peak area of ​​"Pt3") was divided by the sum of the areas of the three Pt separation peaks to calculate the peak area ratio of each Pt separation peak. As a result, the peak area ratio of the first platinum particle was calculated to be 0.271, the peak area ratio of the second platinum particle was calculated to be 0.704, and the peak area ratio of the third platinum particle was calculated to be 0.025. The density of the platinum particles was 21.45 x 10 6 g / m 3 and the platinum atomic fraction is 1.

[0174] Then, for each of these peaks, the value of "6 / density / crystallite diameter x peak area ratio x platinum atom ratio" was calculated, and the values ​​for all peaks were added together to calculate the geometric specific surface area of ​​platinum contained in the catalytic metal particles. Specifically, the geometric specific surface area of ​​platinum contained in the catalytic metal particles supported on the metal-supported catalyst of Example 1 was calculated as 125.4 (m) by the following formula: 2The geometric specific surface area (m / g-Pt) of platinum contained in the catalytic metal particles was calculated. 2 / g‐Pt) = {6 / (21.45 × 10 6 ) / (1.10×10 ―9 )×0.271×1}+{6 / (21.45×10 6 ) / (3.52×10 ―9 )×0.704×1}+{6 / (21.45×10 6 ) / (15.30×10 ―9 )×0.025×1}.

[0175] 3 shows the results of peak separation of the diffraction peaks at a diffraction angle (2θ) of about 40° (within the range of 39° to 44°) in the XRD pattern obtained for the metal-supported catalyst of Example 9. Hereinafter, the peak separation of Example 9 will be described.

[0176] In the XRD pattern obtained by powder XRD measurement of the metal-supported catalyst of Example 9, after baseline correction, a diffraction line with a peak top at a diffraction angle (2θ) of approximately 40.0° appeared. This diffraction line was thought to include at least the diffraction line of the platinum-cobalt alloy Pt7Co. Therefore, it was separated into two components consisting of the peak of the platinum-cobalt alloy Pt7Co and a peak derived from carbon.

[0177] However, optimization of the two components, the peak of the platinum-cobalt alloy Pt7Co and the peak derived from carbon, failed to reproduce the shape of the peak top at a diffraction angle (2θ) of around 40.0°. Therefore, it was thought that, at a diffraction angle (2θ) of around 40.0°, the diffraction line of the first platinum-cobalt alloy Pt7Co, which has a relatively large full width at half maximum, was mixed with the diffraction line of the second platinum-cobalt alloy Pt7Co, which has a different crystallite diameter from the first platinum-cobalt alloy Pt7Co and an even smaller full width at half maximum. Therefore, the peak was separated into three components: the peak of the first platinum-cobalt alloy Pt7Co, the peak of the second platinum-cobalt alloy Pt7Co, and the peak derived from carbon.

[0178] By optimizing the three components, the peak top intensity near a diffraction angle (2θ) of 40.0° could be reproduced, but the broadening of the base of the diffraction line near a diffraction angle (2θ) of 34° to 38° could not be reproduced. Therefore, it was thought that the diffraction line of pure platinum was also mixed in near a diffraction angle (2θ) of 34° to 38°. Therefore, using the peak separation method described above, the diffraction line near a diffraction angle (2θ) of 40° was separated into four components consisting of a peak derived from the first platinum, a peak derived from the first platinum-cobalt alloy Pt7Co, a peak derived from the second platinum-cobalt alloy Pt7Co, and a peak derived from carbon.

[0179] As a result of separating the four components, the residual sum of squares was reduced and became extremely small, and the peak obtained by adding up the peaks of these four components almost completely matched the diffraction line after "baseline correction." Therefore, it was concluded that the metal-supported catalyst of Example 9 supported platinum particles and first platinum-cobalt alloy Pt7Co particles and second platinum-cobalt alloy Pt7Co particles as platinum particles and platinum-cobalt alloy particles.

[0180] Here, in Figure 3, the diffraction lines "after baseline correction" indicate the diffraction lines obtained by applying baseline correction to the diffraction lines obtained by XRD measurement, and the "Pt1" peak, the "Pt7Co_1" peak, the "Pt7Co_2" peak, and the "Carbon" peak indicate the peak derived from the first platinum, the peak derived from the first platinum-cobalt alloy Pt7Co, the peak derived from the second platinum-cobalt alloy Pt7Co, and the peak derived from carbon, respectively, obtained by peak separation of the "after baseline correction" diffraction lines.

[0181] The crystallite diameters of the first platinum particles, the first platinum-cobalt alloy Pt7Co particles, and the second platinum-cobalt alloy Pt7Co particles were calculated using the Scherrer formula. That is, for example, the crystallite diameter of the first platinum particles was calculated by substituting the diffraction angle and full width at half maximum of the "Pt1" separation peak in the XRD pattern shown in Figure 3 into the Scherrer formula. As a result, the crystallite diameter of the first platinum particles was found to be 1.26 x 10 ―9m, and the crystallite diameter of the first platinum-cobalt alloy Pt7Co particles was calculated to be 3.15 × 10 ―9 m, and the crystallite size of the second platinum-cobalt alloy Pt7Co particles is 9.10 × 10 ―9 It was calculated as m.

[0182] Furthermore, the area of ​​each of the three separated peaks obtained by the above-mentioned peak separation (i.e., the peak area of ​​"Pt1", the peak area of ​​"Pt7Co_1", and the peak area of ​​"Pt7Co_2") was divided by the sum of the areas of the three separated peaks to calculate the peak area ratio of each separated peak. As a result, the peak area ratio of the first platinum particles was calculated to be 0.340, the peak area ratio of the first platinum-cobalt alloy Pt7Co was calculated to be 0.508, and the peak area ratio of the second platinum-cobalt alloy Pt7Co was calculated to be 0.152. The density of the platinum particles was 21.45 x 10 6 g / m 3 The platinum atomic fraction is 1, and the density of the platinum-cobalt alloy Pt7Co particles is 19.88 × 10 6 g / m 3 and the platinum atomic fraction is 0.875.

[0183] Then, for each of these peaks, the value of "6 / density / crystallite diameter x peak area ratio x platinum atom ratio" was calculated, and the geometric specific surface area of ​​platinum contained in the catalytic metal particles was calculated by adding up the values ​​of all the peaks. Specifically, the geometric specific surface area of ​​platinum contained in the catalytic metal particles supported on the metal-supported catalyst of Example 9 was calculated as 122.5 m using the following formula: 2 The geometric specific surface area (m 2 / g‐Pt) = {6 / (21.45 × 10 6 ) / (1.26×10 ―9 )×0.340×1}+{6 / (19.88×10 6 ) / (3.15×10 ―9 )×0.508×0.875}+{6 / (19.88×10 6 ) / (9.10×10 ―9 )×0.152×0.875}.

[0184] [Carbon anchoring ratio] For each metal-supported catalyst, the ECSA (m 2 / g-Pt), and the geometric specific surface area (m 2 / g-Pt) was used as the "electrochemically effective specific surface area" and the "geometric specific surface area" in the following formula (I), respectively, to calculate the carbon anchoring ratio (%). That is, the carbon anchoring ratio (%) is calculated by multiplying the ECSA (m 2 / g-Pt) is the geometric specific surface area of ​​platinum (m 2 The value was divided by the ion exchange coefficient (Pt / g-Pt), subtracted from 1, and multiplied by 100. JPEG0007812251000008.jpg21170

[0185] [Carbon anchoring amount] For each metal-supported catalyst, the platinum content (wt%) and the geometric specific surface area (m 2 / g‐Pt), and ECSA of platinum (m 2 / g-Pt) was used as the "precious metal content (wt%)," "geometric specific surface area," and "electrochemically effective specific surface area" in the following formula (II), respectively, to calculate the carbon anchoring amount. 2 / g) is the platinum content (wt%) divided by 100 plus the geometric specific surface area (m 2 / g-Pt) and ESCA of platinum (m 2 / g-Pt) and multiplied by the difference. JPEG0007812251000009.jpg28170

[0186] [Durability Index] For each metal-supported catalyst, the carbon anchoring ratio (%) obtained as described above and the Raman D half-width at half maximum (cm) obtained as described above were used. -1 ) and the durability index was calculated according to the following formula (III). JPEG0007812251000010.jpg21170

[0187] [Performance evaluation of batteries with electrodes containing metal-supported catalysts] The performance of a fuel cell having a cathode containing a metal-supported catalyst was evaluated. Specifically, a cell cathode was fabricated with a catalyst layer containing the metal-supported catalyst. Specifically, an electrolyte solution was prepared by adding 0.25 g of the metal-supported catalyst to the carbon support in an amount such that the weight ratio of the electrolyte to the carbon support was 1.1 (equivalent mass EW = 820), followed by 2 g each of distilled water and 1-propanol. This electrolyte solution was placed in a pot with 25 g of balls and mixed in a ball mill at 200 rpm for 50 minutes to obtain a slurry-like catalyst layer composition containing the uniformly dispersed metal-supported catalyst.

[0188] The resulting slurry composition for catalyst layer was applied to a gas diffusion layer ("29BC", manufactured by SGL Carbon Co., Ltd.) (2.3 cm x 2.3 cm) with an area of ​​5 cm 2 The platinum content per unit area of ​​the battery electrode is 0.2 (mg-Pt / cm 2 ) and dried to form a catalyst layer on the gas diffusion layer. In this way, a battery electrode having a catalyst layer containing a metal-supported catalyst formed thereon was obtained.

[0189] Next, a fuel cell including a cell electrode on which a catalyst layer containing a metal-supported catalyst was formed was manufactured. That is, the cell electrode including the catalyst layer (cathode catalyst layer) manufactured as described above was used as the positive electrode.

[0190] On the other hand, the negative electrode was prepared as follows. 0.5 g of Pt / C (a catalyst containing platinum particles supported on a carbon support: UNPC40-II, manufactured by Ishifuku Metal Industries Co., Ltd.), 10 g of 5% Nafion (registered trademark), 2 g of distilled water, and 25 g of balls were placed in a pot and mixed in a ball mill at 200 rpm for 50 minutes to prepare a slurry Pt / C composition. This slurry Pt / C composition was then applied to a gas diffusion layer (5 cm 2 ) with a platinum content per unit area of ​​0.1 (mg-Pt / cm 2) was used to prepare a negative electrode including a catalyst layer (negative electrode catalyst layer) formed from the Pt / C composition in the same manner as the positive electrode.

[0191] A solid polymer electrolyte membrane (NAFION (registered trademark) 211 manufactured by DuPont) was then placed between the positive electrode catalyst layer and the negative electrode catalyst layer, and these were pressure-bonded at 150°C and 1 MPa for 3 minutes to produce an MEA. A pair of gaskets was attached to this MEA, which was then sandwiched between a pair of separators to produce a single fuel cell. The single cell produced as described above was then installed in an automatic fuel cell evaluation system (manufactured by Toyo Corporation), and first a power generation test was performed, followed by a durability test.

[0192] The power generation test was carried out by supplying saturated humidified air (oxygen) to the positive electrode side at 2.5 L / min (relative humidity 100%) with a back pressure of 150 kPa and saturated humidified hydrogen to the negative electrode side at 1.0 L / min (relative humidity 100%). The cell temperature was set to 75°C and the open circuit voltage was measured for 5 minutes. After that, the cell current density was increased to 4.0 A / cm. 2 to 0 A / cm 2 The cell voltage was measured while maintaining each current density for 3 minutes.

[0193] And the output characteristics are current density 2.5A / cm 2 The voltage (mV) at a current density of 0.2 A / cm was measured as the catalytic activity. 2 The voltage (mV) at which the durability test was started was measured at a current density of 1.0 A / cm. 2 The voltage (mV) at

[0194] Next, a durability test was conducted by setting the cell temperature to 70°C, supplying saturated humidified nitrogen to both sides of the single cell at 0.5 L / min (relative humidity 100%) under a back pressure of 35 kPa, and supplying saturated humidified hydrogen to the anode side at 0.5 mL / min (relative humidity 100%), and repeating a square wave cycle of holding the potential at 0.6 V for 10 seconds and then at 1.2 V for 3 seconds.

[0195] After repeating the above square wave cycle 10,000 times, the power generation test was conducted again, and the current density after the durability test was 1.0 A / cm 2 The voltage (mV) at 1.0 A / cm was measured as the initial performance in the power generation test before the durability test. 2 From the voltage (mV) at 1.0A / cm2 measured in the power generation test after the durability test, 2 The voltage loss (mV) obtained by subtracting the voltage (mV) at 10000 cycles (voltage (mV) after 10000 cycles) was used as an index of durability in the durability test.

[0196] [result] FIG. 4A shows the production conditions for the metal-supported catalysts of Examples 1 to 9 and C1 to C7, and the results of evaluating the characteristics of fuel cells containing the metal-supported catalysts.

[0197] As described above, the durability test was performed at potentials of 0.6 V and 1.2 V. In an environment where the potential is relatively high, such as around 1.2 V, deterioration due to oxidation of the catalytic metal particles and / or carbon support is likely to proceed. On the other hand, in an environment where the potential is relatively low, such as around 0.6 V, deterioration (e.g., aggregation and / or dissolution of the catalytic metal particles supported on the carbon support) is likely to proceed when the once oxidized catalytic metal particles and / or carbon support are reduced. Therefore, the smaller the voltage loss in the durability test, the higher the durability of the carbon support and catalytic metal particles contained in the metal-supported catalyst.

[0198] In this regard, according to the voltage loss in the durability test shown in Fig. 4A, the durability of the metal-supported catalysts of Examples 1 to 9 was superior to that of Examples C1, C3, and C5, and was comparable to that of Example C2. Furthermore, the durability of the metal-supported catalysts of Examples 1, 3 to 5, and 8 was superior to that of Examples 2, 6, 7, and 9, and the durability of the metal-supported catalysts of Examples 3 and 8 was superior to that of Examples 1, 4, and 5. The metal-supported catalysts of Examples C4, C6, and C7 showed significant deterioration in the durability test, making measurement difficult.

[0199] Current density of 2.5A / cm showing the power output characteristics of the metal-supported catalyst2 The larger the voltage (mV) at 2.0 A / cm, the better the output characteristics of the metal-supported catalyst. 2 In the above-mentioned high current density region, a large amount of water is produced, filling the pores of the carbon support with produced water and inhibiting material transport, which tends to result in a decrease in voltage as a battery performance factor.

[0200] 4A, the output characteristics of the metal-supported catalysts of Examples 1 to 9 were superior to those of Examples C2, C3, and C5 to C7, and were comparable to those of Examples C1 and C4. Furthermore, the output characteristics of Examples 1 to 7 and 9 were superior to that of Example 8, and the output characteristics of Example 9 were superior to those of Examples 1 to 7.

[0201] Current density of 0.2 A / cm indicates catalytic activity of metal-supported catalysts 2 The higher the voltage (mV) at 0.2 A / cm, the better the catalytic activity of the metal-supported catalyst. That is, the overvoltage of a fuel cell is classified into activation overvoltage, resistance overvoltage, and diffusion overvoltage. 2 In this case, the influence of the resistance overpotential and the diffusion overpotential is small, so it is suitable for evaluating catalytic activity.

[0202] 4A, the catalytic activities of the metal-supported catalysts of Examples 1 to 9 were superior to those of Examples C2, C5, and C6, and comparable to those of Examples C1, C3, C4, and C7. The catalytic activities of Examples 1 to 7 and 9 were superior to that of Example 8, and the catalytic activity of Example 9 was superior to that of Examples 1 to 7.

[0203] 4B shows the results of evaluating the properties of the metal-supported catalysts of each example. The Raman D half-width at half maximum of the metal-supported catalysts of Examples 1 to 9 was larger than that of Examples C2 and C5, comparable to that of Examples C1 and C3, and smaller than that of Examples C4, C6, and C7. The metal-supported catalysts of Examples 2 to 9 also had a smaller Raman D half-width at half maximum than that of Example 1, and the metal-supported catalysts of Examples 3 to 9 also had a smaller Raman D half-width at half maximum than that of Example 2.

[0204] The BET specific surface area of ​​the metal-supported catalysts of Examples 1 to 9 was larger than that of Examples C2 and C5 to C7, comparable to that of Examples C3 and C4, and smaller than that of Example C1. The metal-supported catalysts of Examples 1 to 4 and 7 to 9 also had a larger BET specific surface area than that of Examples 5 and 6, and the metal-supported catalysts of Examples 1 to 3 and 9 also had a larger BET specific surface area than that of Examples 4, 7, and 8.

[0205] The average pore diameters of the metal-supported catalysts of Examples 1 to 9 were comparable to those of Examples C1, C3, C4, and C7, but smaller than those of Examples C2, C5, and C6. The metal-supported catalysts of Examples 1 to 5 and 7 to 9 had average pore diameters smaller than that of Example 6, and the metal-supported catalysts of Examples 1 to 3 and 9 had average pore diameters smaller than those of Examples 4, 5, 7, and 9.

[0206] The metal-supported catalysts of Examples 1 to 9 had a larger volume ratio of less than 5 nm / 5-70 nm pores than those of Examples C2, C4, and C5, and similar to those of Examples C1, C3, C6, and C7. The metal-supported catalysts of Examples 1 to 5 and 7 to 9 had a larger volume ratio of less than 5 nm / 5-70 nm pores than that of Example 6, the metal-supported catalysts of Examples 1 to 4 and 7 to 9 had a larger volume ratio of less than 5 nm / 5-70 nm pores than that of Example 5, and the metal-supported catalysts of Examples 1 to 3 and 9 had a larger volume ratio of less than 5 nm / 5-70 nm pores than that of Examples 4, 7, and 8.

[0207] Regarding the platinum content, the metal-supported catalysts of Examples 1 to 9 had platinum contents comparable to those of Examples C1 to C7. In addition, the metal-supported catalysts of Examples 1 to 8 had platinum contents greater than that of Example 9.

[0208] The ECSA of platinum in the metal-supported catalysts of Examples 1 to 9 was larger than that in Examples C2 to C5, comparable to that in Example C8, and smaller than that in Examples C1 and C7. The ECSA of platinum in the metal-supported catalysts of Examples 1 to 4, 6, 7, and 9 was larger than that in Examples 5 and 8, and the ECSA of platinum in Examples 2 to 4, 7, and 9 was larger than that in Examples 1 and 6.

[0209] Regarding the geometric specific surface area of ​​platinum, the metal-supported catalysts of Examples 1 to 9 had a platinum geometric specific surface area larger than that of Examples C2, C3, and C5, comparable to that of Example C4, and smaller than that of Examples C1, C6, and C7. In addition, the metal-supported catalysts of Examples 1 to 4, 6, 7, and 9 had a platinum geometric specific surface area larger than that of Examples 5 and 8, and the metal-supported catalysts of Examples 1 to 4, 7, and 9 had a platinum geometric specific surface area larger than that of Example 6.

[0210] Regarding the carbon anchoring ratio, the metal-supported catalysts of Examples 1 to 9 had a carbon anchoring ratio greater than that of Examples C1 to C3 and C5, but smaller than that of Examples C4, C6 and C7. Furthermore, the metal-supported catalysts of Examples 1 to 6, 8 and 9 had a carbon anchoring ratio greater than that of Example 7, and the metal-supported catalysts of Examples 1, 3 and 9 had a carbon anchoring ratio greater than that of Examples 2, 4, 5 and 8. Furthermore, the metal-supported catalysts of Examples 3 and 9 had a carbon anchoring ratio smaller than that of Example 1.

[0211] Regarding the carbon anchoring amount, the metal-supported catalysts of Examples 1 to 9 had a carbon anchoring amount greater than that of Examples C1 to C3 and C5, comparable to that of Example C4, and smaller than that of Examples C6 and C7. Furthermore, the metal-supported catalysts of Examples 1 to 4, 6 and 9 had a carbon anchoring amount greater than that of Examples 5, 7 and 8, and the metal-supported catalysts of Examples 1 to 3 and 9 had a carbon anchoring amount greater than that of Examples 4 and 6. Furthermore, the metal-supported catalysts of Examples 2, 3 and 9 had a carbon anchoring ratio smaller than that of Example 1.

[0212] The durability index of the metal-supported catalysts of Examples 1 to 9 was higher than that of Examples C1, C3, C6, and C7, and comparable to that of Examples C2, C4, and C5. The metal-supported catalysts of Examples 1, 3 to 6, 8, and 9 had a higher durability index than that of Examples 2 and 7, the metal-supported catalysts of Examples 3 to 6, 8, and 9 had a higher durability index than that of Example 1, and the metal-supported catalysts of Examples 3 and 9 had a higher durability index than that of Examples 4 to 6, and 8.

Claims

1. a carbon support; catalytic metal particles containing a noble metal supported on the carbon support; A metal supported catalyst comprising: The Raman spectrum obtained by Raman spectroscopy shows a Raman shift of 1340 cm －１ The half width at half maximum of the D band having a peak top in the vicinity is 50.0 cm －１ is as follows: The carbon anchoring ratio calculated by the following formula (I) is 15.0% or more. (In the above formula (I), the "electrochemically effective specific surface area" and the "geometric specific surface area" respectively refer to the electrochemically effective specific surface area (m ) of the noble metal contained in the metal-supported catalyst, which are obtained by cyclic voltammetry using a rotating ring-disk electrode apparatus having a working electrode on which the metal-supported catalyst is supported, where the potential is swept at a sweep rate of 10 mV / sec.) ２ / g-noble metal), and the geometric specific surface area (m ) of the precious metal contained in the metal-supported catalyst, which is obtained by performing peak separation of the (111) diffraction line of the precious metal appearing in an X-ray diffraction pattern obtained by powder X-ray diffraction of the metal-supported catalyst, calculating the value of "6 / density / crystallite diameter × peak area ratio × precious metal atom ratio" for each of the peaks obtained by the peak separation, and adding up the calculated values ​​for all the peaks. ２ / g-precious metal). Metal-supported catalysts.

2. The average pore diameter is 8.0 nm or less. The metal supported catalyst of claim 1.

3. The volume (cm) of pores with a pore diameter of 5 nm or more and 70 nm or less ３ / g-carbon support) vs. the volume of pores with a diameter of less than 5 nm (cm ３ / g-carbon support) is 1.5 or more; The metal-supported catalyst according to claim 1 or 2.

4. BET specific surface area is 350 (m ２ / g-carbon support) or more, The metal-supported catalyst according to any one of claims 1 to 3.

5. The weight ratio of the noble metal to the weight of the metal-supported catalyst is 30% by weight or more. The metal-supported catalyst according to any one of claims 1 to 4.

6. The electrochemically effective specific surface area of ​​the noble metal contained in the metal-supported catalyst is 45 (m ２ / g-precious metal) or more, The metal-supported catalyst according to any one of claims 1 to 5.

7. The geometric specific surface area of ​​the noble metal contained in the metal-supported catalyst is 52 (m ２ / g-precious metal) or more, The metal-supported catalyst according to any one of claims 1 to 6.

8. The carbon anchoring amount calculated by the following formula (II) is 5.0 m ２ / g or more, (In the above formula (II), "precious metal content (wt%)" refers to the ratio of the weight of the precious metal to the weight of the metal-supported catalyst, and "geometric specific surface area" and "electrochemically effective specific surface area" refer to the geometric specific surface area (m ２ / g-noble metal) and electrochemically effective specific surface area (m ２ / g-precious metal). The metal-supported catalyst according to any one of claims 1 to 7.

9. The durability index calculated by the following formula (III) is 0.50 cm or more. (In the above formula (III), the "carbon anchoring ratio (%)" is calculated by the above formula (I), and the "Raman D half width at half maximum" is the half width at half maximum of the D band (cm －１ ) The metal-supported catalyst according to any one of claims 1 to 8.

10. The catalyst comprises the metal-supported catalyst according to any one of claims 1 to 9. electrode.

11. 11. The electrode of claim 10, battery.

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