Cation vacancy activating surface neighboring sites for efficient CO2 photoreduction on Bi4Ti3O12 nanosheets

Inefficient charge separation and insufficient surface catalytic sites remain the main impediment in developing highly efficient and selective catalysts for CO2 photoreduction. Surface defects are effective, but their function is always constrained within the defect location. Herein, a desirable surface cation vacancy strategy is implemented to solve the above obstacles over Bi4Ti3O12 nanosheets. The surface Ti vacancy (V-Ti) creates an atomic-level charge transfer channel on the surface of Bi4Ti3O12, allowing a rapid transfer of photon-generated electrons from the V-Ti site of neighboring Ti and O atoms to CO2 molecules. More importantly, V-Ti activates neighboring Ti and O atoms, which allows them a stronger ability for enhancing CO2 adsorption and conversion. Thus, a convenient and swift charge transfer channel and activated near surface region are formed on the surface of Bi4Ti3O12, profoundly boosting the CO2 reduction process, as evidenced by experimental and theoretical results collectively. Without any sacrificial agents or cocatalysts, Bi4Ti3O12 with an optimal V-Ti concentration exhibits an outstanding CO production rate of 15.17 mu mol g(-1) h(-1), nearly 5 times higher than that of pristine Bi4Ti3O12. This work unfolds a new function of surface cation vacancies to substantially enhance CO2 photoreduction.