Periodic Frustrated Lewis Pairs on Bimetallic Oxide Semiconductors for CO2 Adsorption and Photocatalytic Conversion

Lewis acids (LAs) or Lewis bases (LBs) have been recognized as crucial catalytically active sites for enhancing the adsorption and conversion of inert CO₂. However, engineering of periodic frustrated Lewis pairs (PFLPs) on the surfaces of semiconductor photocatalysts presents significant challenges, and the synergistic mechanism of PFLPs in CO₂ photoreduction remains unclear. In this study, we propose a strategy that utilizes periodic oxygen vacancies to engineer dual-metallic PFLPs on bimetallic oxide semiconductor surfaces. We employ SrNb₂O_6-x as a model photocatalyst to elucidate the synergistic effect of PFLPs on CO₂ photoreduction. Within each FLP unit, the LA (Sr²⁺) captures an O atom from CO₂ while the LB (Nb⁴⁺) engages in an interaction with the C atom and concurrently facilitates transfer of photoinduced electrons from SrNb₂O_6-x to adsorbed CO₂. Thus, SrNb₂O_6-x with the PFLPs-enriched surface exhibits ultrahigh CO₂ adsorption and a low energy barrier for CO desorption. Under focused sunlight irradiation, SrNb₂O_6-x demonstrates nearly 100% selectivity in converting CO₂ to CO at a rate of 25.5 μmol g^-1 h^-1. This study presents a method for designing metal PFLPs on inorganic photocatalyst surfaces, which could contribute to the practical implementation of CO₂ photoreduction.