SUBSTRATE COATED WITH CRYSTALLITE OF CATALYST

摘要

A substrate such as carbon, graphite, or various semiconductors is coated with a "two-dimensional" thin film form of flat isolated crystallites of platinum, palladium or silver to form a catalyst useful in a fuel cell. The method of formation of the catalyst is to place the substrate in an electrolyte such as H2PtCl6 about 1% and one molar sulfuric acid. The potentiostatic pulse plating method is employed. A high potential pulse of very short duration is followed by a low potential of substantial duration. The very high potential nucleates crystals at various randomly distributed nucleation sites such as imperfections in the surface of the substrate. The resulting catalyst has a large surface area of hexagonal crystals about 20 to 40 Angstroms in diameter.