Improved photocatalytic CO2 conversion efficiency on Ag loaded porous Ta2O5

Highlights: • A novel Ag loaded mesoporous Ta₂O₅ photocatalyst was prepared for CO₂ reduction. • With stronger CO₂ adsorption ability, porous Ta₂O₅ shows higher selectivity. • Ag loading promotes a charge separation efficiency. • CO₂ molecules are activated due to the strong interaction between Ag and CO₂. The photocatalytic efficiency of CO₂ conversion into carbon-containing products relies on CO₂ adsorption and activation on the surface of photocatalyst. Here, we developed a novel Ag loaded mesoporous Ta₂O₅ photocatalyst with high selectivity using a SiO₂ template method along with an in-situ photodeposition method. Benefitting from the mesoporous structure, the amount of CO₂ adsorbed by porous Ta₂O₅ is 10 times that of bulk Ta₂O₅ and the photogenerated electrons can capture and reduce CO₂ more easily. Moreover, on the surface of Ta₂O₅, Ag particles work as active sites for CO₂ reduction. After Ag loading, not only the charge separation efficiency was significantly promoted, but also the CO₂ molecules on the surface of Ag were activated due to the formation of the strong interaction between Ag and CO₂, thus facilitating the occurrence of CO₂ reduction reaction. The CO and H₂ evolution rates of 1.0% Ag/Ta₂O₅ photocatalyst are 1.76 μmlol g⁻¹ h⁻¹ and 0.18 μmlol g⁻¹ h⁻¹, respectively, and the selectivity of CO₂ reduction to CO reaches 90.7%. This work not only gives guidance for designing photocatalysts with high CO₂ conversion efficiency but also provides insights into the roles of cocatalysts for CO₂ reduction.