Electrode catalyst layer for use in fuel cell
An electrode catalyst layer for use in a fuel cell, the layer having a composite particle material in which catalyst particles are supported on conductive particles, a proton conductive polymer and a metal oxide, wherein said metal oxide is non-particulate.
1. A method of making an electrode catalyst layer comprising:
preparing a catalyst dispersion comprising at least a composite particle material comprising catalyst particles supported on conductive particles, a perfluorocarbon polymer and a medium;
drying and solidifying said catalyst dispersion to form a polymer-containing aggregate;
adding at least one of an oxide precursor of an oxide selected from the group consisting of Al 2 O 3 , B 2 O 3 , SiO 2 , TiO 2 , Y 2 O 3 , ZrO 2 , Zr 2 O 3 and ZrSiO 4 in the catalyst dispersion to form a mixture; and
applying said mixture to a substrate.
2. The method of making an electrode catalyst layer according to claim 1 , wherein part of said catalyst particles is coated with the perfluorocarbon polymer.
3. The method of making an electrode catalyst layer according to claim 1 , wherein said perfluorocarbon polymer contains an oxide selected from the group consisting of Al 2 O 3 , B 2 O 3 , SiO 2 , TiO 2 , Y 2 O 3 , ZrO 2 , Zr 2 O 3 and ZrSiO 4 .
4. The method of making an electrode catalyst layer according to claim 1 , wherein said oxide is silica.
5. The method of making an electrode catalyst layer according to claim 1 , wherein the mass ratio of the oxide to the perfluorocarbon polymer is from 0.001 to 50.
6. The method of making an electrode catalyst layer according to claim 1 , wherein said oxide is obtained by subjecting an alkoxide to hydrolysis and polycondensation reactions.
7. The method of making an electrode catalyst layer according to claim 6 , wherein said hydrolysis reaction is conducted under an acidic condition.
8. The method of making an electrode catalyst layer according to claim 1 , wherein two or more of said oxide precursor are used.
9. The method of making an electrode catalyst layer according to claim 1 , wherein said medium is selected from the group consisting of water, ethanol, ethyleneglycol, propyleneglycol, glycerin, dimethylsulfoxide, and composite mediums containing a mixture thereof.
10. The method of making an electrode catalyst layer according to claim 1 , wherein said substrate is selected from the group consisting of an ion exchange polymer membrane, a gas diffusion layer and a PTFE membrane.