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.