Mechanism of photocatalytic reduction of CO2 to CH4 on F-doped defective anatase TiO2(101) surface: A density functional theory study

Abstract

Photocatalytic reduction of CO2 into CH4 has attracted comprehensive concerns as an effective solution to meet the energy crisis and global warming. F-doped defective anatase TiO2 was reported to effectively improve the photocatalytic efficiency and the selectivity of CH4 generation. However, the mechanism behind it remains unclear. Herein, we systematically studied the photocatalytic pathway of CO2 reduction to CH4 on F-doped defective anatase TiO2(101) by density functional calculations. First, we found that F doping leads to the enhanced reduction potential of photoexcited electrons. Furthermore, we identified a thermodynamically feasible reaction path: CO2→CO/HCOO→CHO→CH2O→CH3O→CH3OH→CH3→CH4. The whole reaction is exothermic, elucidating an extremely strong reduction activity of the TiO2(101) surface. Our work provides some new insights into the CO2 reduction mechanisms of F-doped TiO2, which will help to design TiO2-related photocatalysts with high catalytic performance.