Oxygen vacancy-engineered ultrathin Bi24O31Br10 for visible light-driven CO2 reduction with nearly 100% CO selectivity in pure water

Photocatalytic CO2 reduction performance is still unsatisfactory main due to the low separation efficiency of photogenerated electron-hole pairs, insufficient of active sites, and poor activation of CO2. Defect engineering is an effective strategy to address these issues. Herein, we firstly reported that one ultrathin Bi24O31Br10 nanosheet with abundant oxygen vacancy is fabricated via one-step hydrothermal approach. Electron paramagnetic resonance (EPR) spectra confirmed that different concentrations of oxygen vacancies are deliberately created on the surfaces of Bi24O31Br10 nanosheets by adjusting the amount of ethylene glycol (EG). Density of states function theory (DFT) calculations revealed the generation of stronger local charge around the oxygen vacancies (Vo), which promoted the dissociation of CO2 and facilitated the production of COOH* intermediate conversed from CO2. Meanwhile, adsorption energy calculations indicated that the Vo favor the adsorption of CO2. As a result, without cocatalysts or sacrificial agents, the ultrathin Vo-R Bi24O31Br10 nanosheets delivers a nearly 100% of CO selectivity with high CO yield rate of 14.80 μmol g−1h−1 in pure water under visible light.