Defect Engineering via La Doping and Hydrogenation on Bi4Ti3O12 for Synergistically Enhancing Photocatalytic CO2 to CH3OH

Developing highly efficient photocatalysts for CO2 reduction remains a great challenge. The large band gap and poor charge carrier dynamics are the major factors limiting the performance of Bi4Ti3O12 (BTO). Herein, a series of La-doped Bi4Ti3O12 (BLaxTO) nanosheets were synthesized and further modified by NaBH4 hydrogenation to create surface defect-rich H-BLaXTO nanosheets. Characterizations and theoretical calculations confirmed that the synergistic effect of La doping and hydrogenation significantly enhanced visible-light absorption, promoted charge separation, and improved the electron reduction capacity. When applied to photocatalytic CO2 reduction, the H-BLa0.2TO catalyst achieved a superior CH3OH production rate of 7.90 μmol·g−1·h−1, which is 5.6 times higher than that of pristine Bi4Ti3O12. Moreover, the H-BLa0.2TO catalyst maintained excellent stability over four consecutive cycles. This study offers an integrated strategy for constructing high-performance bismuth-based photocatalysts through elemental doping and defect engineering.