The photoreduction of acetylene by band-gap irradiation of TiO2 using Mo2O4(diethyldithiocarbamate)(2) as a catalyst

The photoreduction of acetylene is catalyzed by Mo2O4(dedtc)(2) (dedtc, diethyldithiocarbamate) in the presence of 5-8 nm diameter colloidal TiO2. This photocatalytic process exhibits optimum activity at pH 6 and a loading of 30 catalyst molecules per TiO2 particle. The same catalytic site(s) are responsible for C2H2 reduction to C2H4 and C2H6 and H+ reduction to H-2. The overall photonic efficiency is 1.3% for the transfer of reducing equivalents to products at full lamp intensity, and increases with decreasing intensity. The effects of pH, temperature, intensity and loading on the catalytic process are consistent with a mechanism in which the catalytic site associated with the TiO, surface promotes the transfer of H atoms or electrons to the bound substrate. The photocatalytic properties of this neutral molecular complex are compared with those observed for other Mo-containing catalysts. (C) 1997 Elsevier Science S.A.