Carbon dioxide reduction under visible light: a comparison of cadmium sulfide and titania photocatalysts

Photocatalysts based on titania and solid solutions of cadmium and zinc sulfides with deposited metals (Pt, Ag) were compared in CO2 reduction under visible light. In the presence of titania- and cadmium sulfide-based photocatalysts, the dominant reduction products were CH4 and CO, respectively, due to different positions of the conduction band level for these semiconductors. The deposition of metals on the surface of both TiO2- and CdS-based samples increased the molar concentration of methane in the reaction products.