Surface-modified Ag@Ru-P25 for photocatalytic CO₂ conversion with high selectivity over CH₄ formation at the solid-gas interface

Systematic optimization of the photocatalyst and investigation of the role of each component is important to maximizing catalytic activity and comprehending the photocatalytic conversion of CO2 reduction to solar fuels. A surface-modified Ag@Ru-P25 photocatalyst with H2O2 treatment was designed in this study to convert CO2 and H2O vapor into highly selective CH4. Ru doping followed by Ag nanoparticles (NPs) cocatalyst deposition on P25 (TiO2) enhances visible light absorption and charge separation, whereas H2O2 treatment modifies the surface of the photocatalyst with hydroxyl (-OH) groups and promotes CO2 adsorption. High-resonance transmission electron microscopy, X-ray photoelectron spectroscopy, X-ray absorption near-edge structure, and extended X-ray absorption fine structure techniques were used to analyze the surface and chemical composition of the photocatalyst, while thermogravimetric analysis, CO2 adsorption isotherm, and temperature programmed desorption study were performed to examine the significance of H2O2 treatment in increasing CO2 reduction activity. The optimized Ag-1.0@Ru-1.0-P25 photocatalyst performed excellent CO2 reduction activity into CO, CH4, and C2H6 with a similar to 95% selectivity of CH4, where the activity was similar to 135 times higher than that of pristine TiO2 (P25). For the first time, this work explored the effect of H2O2 treatment on the photocatalyst that dramatically increases CO2 reduction activity.