Low-coordination transition metal sites on oxygen vacancy enriched strontium titanate-based perovskites enable highly selective photocatalytic CO2 reduction to CH4

Abstract

The photochemical conversion of CO2 into high-value single hydrocarbon fuels such as CH4 remains a challenge. Here we have prepared a series of perovskites VO-SrTiMO3 (M = Mn, Fe, Co) with rich oxygen vacancies. Among them, Mn-doped perovskite (VO-STMn0.2) exhibited 18.21 μmol g−1 yield and nearly 100 % selectivity for CH4, as well as excellent reproducibility of about 15 h. Through a combination of advanced characterization and theoretical calculations, we found that the low-coordination transition metal site was able to stabilize the critical COOH* and CO* intermediates, thereby altering the reaction pathway to form CH4 instead of CO. Most importantly, this work demonstrated that the relative center between the 2p orbitals of the oxygen atom of the CO2 reduction intermediate and the 3d orbitals of the low-coordination metal site regulates the reaction mechanism of CO2 reduction, offering the possibility of achieving efficient photochemical reduction of CO2.