This is an evaluation of the possibility of developing semiconductor- based photocatalysts for multielectron reductions. The hypothesis is that conduction-band electrons produced by band-gap irradiation of semiconductor (titania) colloids may be transmitted to catalytic molybdenum sites on the colloidal surface. The ability of reduced monomeric (from molybdate), dimeric (from molybdenum(V)), and trimeric (from molybdenum(VI)) forms of molybdenum to perform multielectron reduction of substrates is investigated by product analysis. Acetylene reduction is used as a test reaction; reductions of dinitrogen and of carbon dioxide may also be investigated. The effect of derivatization of the colloidal titania surface with molybdocenium dicarboxylate on the efficiency of electron transfer is studied using flash photolysts and luminescence techniques. Time permitting, the work will be extended to zinc oxide and cadmium sulfide colloidal semiconductors. A successful photocatalytic multielectron reduction system could be applied in many areas including synthetic fuels production, fertilizer production, pollution control, polymers, and specialty chemicals.
