Electrocatalytic activity of some carburised nickel, tungsten and molybdenum compounds

Carburisation of some compounds of nickel, tungsten and molybdenum produces powders which show considerable passivity in sulphuric acid at elevated temperature, and which also show some catalytic activity towards the electro-oxidation of methanol and of hydrogen. Of those materials examined, carburised nickel-tungsten, prepared by reduction of nickel tungstate, shows a wide potential range of passivity, and is electroactive towards the anodic oxidation of methanol. The corresponding nickel-molybdenum material shows higher corrosion rates, and some electrocatalytic activity towards the anodic oxidation of hydrogen, but with little detectable catalysis of the methanol oxidation reaction. Reduced nickel and reduced iron on their own give high corrosion rates with no detectable electrocatalytic activity for fuel oxidation. Tungsten carbide on its own shows a high degree of passivity in sulphuric acid. but no electrocatalytic activity for methanol oxidation. (C) 1997 Elsevier Science Ltd.