Effect of transition metal oxide cocatalyst on the photocatalytic activity of Ag loaded CaTiO3 for CO2 reduction with water and water splitting

Abstract Various dual cocatalysts consisting of Ag and transition metal oxide (TMOx) were loaded on a CaTiO3 (CTO) photocatalyst by different loading methods and examined for the photocatalytic CO2 reduction with water as an electron donor. Compared to the results provided with the single Ag cocatalyst, the dual cocatalyst loaded CTO photocatalyst exhibited a similar or less CO evolution rate and higher H2 production, meaning that these photocatalyst showed photocatalytic activity for both CO2 reduction and water splitting. Dual cocatalysts of Ag and TMOx loaded by a photodeposition gave higher CO production rate than those loaded by an impregnation method. The CTO photocatalysts with a single TMOx cocatalyst showed higher activities in both H2 evolution and O2 evolution test than the bare CTO and dual cocatalyst loaded CTO photocatalysts, indicating that the photocatalytic activity for water splitting is suppressed by the Ag cocatalyst but improved by the TMOx.