• Reduction of CO 2 to CH 4 using F-doped defective anatase TiO 2 (101) surface as a photocatalytic reduction site. • It is demonstrated that the F doping leads to the enhanced reduction potential of photoexcited electrons. • Exploring a thermodynamically feasible reaction pathway for the photocatalytic reduction of CO 2 to CH 4. • The high selectivity of F-doped defective anatase TiO 2 for the photocatalytic reduction of CO 2 to CH 4 is explained. Photocatalytic reduction of CO 2 into CH 4 has attracted comprehensive concerns as an effective solution to meet the energy crisis and global warming. F-doped defective anatase TiO 2 was reported to effectively improve the photocatalytic efficiency and the selectivity of CH 4 generation. However, the mechanism behind it remains unclear. Herein, we systematically studied the photocatalytic pathway of CO 2 reduction to CH 4 on F-doped defective anatase TiO 2 (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: CO 2 →CO/HCOO→CHO→CH 2 O→CH 3 O→CH 3 OH→CH 3 →CH 4. The whole reaction is exothermic, elucidating an extremely strong reduction activity of the TiO 2 (101) surface. Our work provides some new insights into the CO 2 reduction mechanisms of F-doped TiO 2 , which will help to design TiO 2 -related photocatalysts with high catalytic performance. [Display omitted] [ABSTRACT FROM AUTHOR]