Revolutionizing CO2 conversion for single-carbon products: Unveiling the photocatalytic magic of M6@TiO2 via First-Principles insights

Abstract

Metal clusters can be loaded as cocatalysts on the surface of TiO₂ to promote the photocatalytic reduction of CO₂. However, the specific mechanism of this reaction is still unclear. This study systematically investigates the performance of metal cluster (M₆, M = Au, Ag, Mn, Cu, Sn, Ga, Mo and Bi) as the cocatalytic on the TiO₂(101) surface towards the CO₂ reduction reaction through density functional theory (DFT) calculations. Metal clusters as co-catalysts supported on TiO₂ can improve the light absorption intensity of photocatalysts. Moreover, it was found that these metal clusters significantly improved the electron transport efficiency of TiO₂, thereby enhancing the efficiency of photocatalytic CO₂ reduction. Cu₆@TiO₂ showed the highest photocatalytic activity, with a maximum Gibbs free energy change (ΔG_max) of 0.46 eV. The study also revealed a strong correlation between catalytic activity and the adsorption strength of key intermediates, indicating that enhancing the adsorption differences of key intermediates can improve the efficiency of photocatalysts. In addition, Mn₆@TiO₂, Cu₆@TiO₂, Mo₆@TiO₂, Au₆@TiO₂, and Ga₆@TiO₂ can effectively suppress the hydrogen evolution reaction (HER), demonstrating excellent photocatalytic performance and high selectivity. This work provides useful insights into the reduction of CO₂ to form single carbon products on TiO₂ catalysts loading metal clusters.