MATERIAL FOR CATALYST LAYER FOR POLYMER ELECTROLYTE FUEL CELL
To improve the utilization efficiency of a noble metal catalyst in a catalyst layer of an electrode for a polymer electrolyte fuel cell. A precursor material obtained by polymerizing a perfluoromonomer having a fluorosulfonyl group in the presence of noble metal catalyst fine particles supported carbon particles, a material for a catalyst layer obtained by converting the fluorosulfonyl groups of the precursor material to sulfonic acid groups, and a membrane/electrode assembly for a polymer electrolyte fuel cell having a catalyst layer using the material for a catalyst layer.
1 . A precursor material of a material for a catalyst layer for a polymer electrolyte fuel cell, comprising carbon particles having noble metal catalyst fine particles supported and a perfluoropolymer having fluorosulfonyl groups, wherein the perfluoropolymer having fluorosulfonyl groups is obtained by polymerizing a perfluoromonomer having a fluorosulfonyl group in the presence of the noble metal catalyst fine particles supported carbon particles.
2 . The precursor material according to claim 1 , which contains from 5 to 300 parts by mass of the perfluoropolymer having fluorosulfonyl groups per 100 parts by mass of carbon of the noble metal catalyst fine particles supported carbon particles.
3 . The precursor material according to claim 1 , wherein the perfluoropolymer having fluorosulfonyl groups is a crosslinked perfluoropolymer.
4 . A material for a catalyst layer for a polymer electrolyte fuel cell, comprising carbon particles having noble metal catalyst fine particles supported and a perfluoropolymer having sulfonic acid groups, wherein the perfluoropolymer having sulfonic acid groups is obtained by polymerizing a perfluoromonomer having a fluorosulfonyl group in the presence of the noble metal catalyst fine particles supported carbon particles, and then converting the fluorosulfonyl groups of the polymer to sulfonic acid groups.
5 . The material for a catalyst layer according to claim 4 , which contains from 5 to 300 parts by mass of the perfluoropolymer having sulfonic acid groups per 100 parts by mass of carbon of the noble metal catalyst fine particles supported carbon particles.
6 . The material for a catalyst layer according to claim 4 , wherein the perfluoropolymer having sulfonic acid groups is a crosslinked perfluoropolymer.
7 . A process for producing a precursor material of a material for a catalyst layer for a polymer electrolyte fuel cell, comprising carbon particles having noble metal catalyst fine particles supported and a perfluoropolymer having fluorosulfonyl groups, which comprises polymerizing a perfluoromonomer having a fluorosulfonyl group in the presence of the noble metal catalyst fine particles supported carbon particles to form the perfluoropolymer having fluorosulfonyl groups.
8 . The process for producing a precursor material according to claim 7 , wherein a perfluoromonomer having no fluorosulfonyl group is copolymerized together with the perfluoromonomer having a fluorosulfonyl group.
9 . The process for producing a precursor material according to claim 8 , wherein the perfluoromonomer having no fluorosulfonyl group is a perfluoromonomer having at least two addition polymerizable groups.
10 . The process for producing a precursor material according to claim 7 , wherein the perfluoromonomer having a fluorosulfonyl group is a perfluoromonomer having a 2-methylene-1,3-dioxolane structure.
11 . The process for producing a precursor material according to claim 7 , wherein polymerization is carried out in an aqueous medium.
12 . The process for producing a precursor material according to claim 7 , wherein the precursor material contains from 5 to 300 parts by mass of the perfluoropolymer having fluorosulfonyl groups per 100 parts by mass of carbon of the noble metal catalyst fine particles supported carbon particles.
13 . A process for producing a material for a catalyst layer for a polymer electrolyte fuel cell, comprising carbon particles having noble metal catalyst fine particles supported and a perfluoropolymer having sulfonic acid groups, which comprises producing the precursor material by the production process as defined in claim 7 , and then converting fluorosulfonyl groups of the polymer in the precursor material to sulfonic acid groups to obtain the perfluoropolymer having sulfonic acid groups.
14 . The process for producing a material for a catalyst layer according to claim 13 , wherein the perfluoropolymer having sulfonic acid groups has an ion exchange capacity of from 0.5 to 3.5 meq/g dry polymer.
15 . A membrane/electrode assembly for a polymer electrolyte fuel cell comprising an anode layer containing a catalyst layer, a cathode layer containing a catalyst layer, and a polymer electrolyte membrane disposed between the anode layer and the cathode layer, wherein the catalyst layer of at least one of the anode layer and the cathode layer contains the material for a catalyst layer as defined in claim 4 .
16 . A process for producing a membrane/electrode assembly for a polymer electrolyte fuel cell comprising an anode layer containing a catalyst layer, a cathode layer containing a catalyst layer, and a polymer electrolyte membrane disposed between the anode layer and the cathode layer, which comprises producing a material for a catalyst layer by the production process as defined in claim 13 , and then forming a catalyst layer using the material for a catalyst layer on at least one side of the polymer electrolyte membrane (provided that when the catalyst layer using the material for a catalyst layer is formed on only one side, the other catalyst layer is formed by another material).