CARBON-TITANIUM OXIDE ELECTROCATALYST SUPPORTS FOR OXYGEN REDUCTION IN PEM FUEL CELLS
A high surface area support material is formed of an intimate mixture of carbon clusters and titanium oxide clusters. A catalytic metal, such as platinum, is deposited on the support particles and the catalyzed material us as an electrocatalyst in an electrochemical cell such as a PEM fuel cell. The composite material is prepared by thermal decomposition and oxidation of an intimate mixture of a precursor carbon polymer, a titanium alkoxide and a surfactant that serves as a molecular template for the mixed precursors.
1 . A method of making porous, carbon and titanium oxide containing particles, the method comprising:
forming a dispersion of a carbonizable polymer, a surfactant, and titanium alkoxide in a liquid medium, the proportions of carbonizable polymer and titanium alkoxide being determined to provide a desired carbon to titanium ratio in the carbon and titanium oxide containing particles;
evaporating the liquid medium to leave a material characterized by inter-dispersed clusters of carbon based polymer, surfactant, and titanium oxide;
heating the material to progressively decompose and volatilize the surfactant and alkoxide residue; and
further heating the material to carbonize the carbonizable polymer, and to yield a porous composite of inter-dispersed carbon and titanium oxide.
2 . A method of making porous carbon and titanium oxide containing particles as recited in claim 1 in which the carbonizable polymer is a phenol-formaldehyde polymer.
3 . A method of making porous carbon and titanium oxide containing particles as recited in claim 1 in which the liquid medium comprises water and an alcohol.
4 . A method of making porous carbon and titanium oxide containing particles as recited in claim 1 in which the surfactant is a block copolymer comprising polypropylene oxide central blocks and polyethylene oxide end blocks.
5 . A method of making porous carbon and titanium oxide containing particles as recited in claim 1 in which the surfactant is a block copolymer comprising polypropylene oxide central blocks and polyethylene oxide end blocks and the liquid medium comprises water and an alcohol.
6 . A supported catalyst comprising particulate catalyst support material having high surface area and the particles consisting essentially of intermixed carbon and titanium oxide.
7 . A supported catalyst as recited in claim 6 comprising particles of a catalyst metal carried on support particles consisting essentially of intermixed carbon and titanium oxide.
8 . A supported catalyst as recited in claim 7 in which the catalyst metal comprises platinum or a platinum-group metal.
9 . A polymer electrolyte membrane fuel cell comprising an electrode for the reduction of oxygen, the electrode comprising catalyst support particles comprising intermixed carbon and titanium oxide.
10 . A polymer electrolyte membrane fuel cell as recited in claim 9 in which the catalyst support particles consist essentially of intermixed carbon and titanium oxide.
11 . A polymer electrolyte membrane fuel cell as recited in claim 9 comprising a supported catalyst comprising particles of a catalyst metal carried on particles consisting essentially of intermixed carbon and titanium oxide.
12 . A polymer electrolyte membrane fuel cell as recited in claim 11 in which the catalyst metal comprises platinum or a platinum-group metal.