Preloaded oxygen vacancy conditioning Ni/TiO2 to enhance photocatalytic CO2 reduction

The regulation of oxygen vacancy (OV) defects plays a critical role in facilitating photocatalytic reactions. In this study, Nix/TiO2-OV photocatalytic materials with ultra-high oxygen vacancy concentrations (>33%) were prepared by preloading oxygen vacancies on Ni/TiO2 system. The experimental results show that the catalytic performance initially rises and subsequently declines with an increase in oxygen vacancy concentration. Among the samples, the best one (8Ni/TiO2-OV2) exhibits a noteworthy photocatalytic yield of CO (22.654 μmol·g−1·h−1) and CH4 (3.93 μmol·g−1·h−1). Density functional theory (DFT) shows that the excellent catalytic performance of 8Ni/TiO2-OV2 is due to that oxygen vacancy is in favour of the narrowing of the band gap, thereby promoting the excitation and efficient transfer of electrons. This study presents a promising novel method for obtaining ultra-high concentration of oxygen vacancies and explores the relationship between oxygen vacancy concentration and catalytic performance.