Enhanced CO2 conversion on highly-strained and oxygen-deficient BiVO4 photocatalyst

Bismuth vanadate (BiVO4) has recently received significant attention for photocatalytic CO2 conversion due to its low bandgap and high stability, but low position of the conduction band and high electron-hole recombination rate limit its photocatalytic activity. In this study, to overcome the drawbacks of BiVO4, oxygen vacancies and lattice strain are simultaneously introduced in this oxide using a high-pressure torsion process. The processed material not only shows the low recombination rate and enhanced conduction band level but also exhibits bandgap narrowing. The oxygen-deficient and highly-strained BiVO4 shows a high photocatalytic CO2 conversion rate with an activity comparable to the P25 TiO2 photocatalyst. The enhancement of photocatalytic activity is discussed based on the modification of band structure, enhanced light absorbance, the lifetime of excited electrons, and the role of oxygen vacancies as activation sites for CO2 photoreduction. This work introduces a feasible pathway to develop active photocatalysts for CO2 conversion by lattice strain and defect engineering.