Constructing charge transfer channel between dopants and oxygen vacancies for enhanced visible-light-driven water oxidation

Photocatalytic water oxidation is a crucial step in water splitting, but is generally restricted by the slow kinetics. Therefore, it is necessary to develop high-performance water oxidation photocatalysts. Herein, the Fe-doped Bi₂WO₆ nanosheets with oxygen vacancies (OVs) were synthesized for enhanced photocatalytic water oxidation efficiency, showing a synergistic effect between Fe dopants and OVs. When a molar fraction of 2% Fe was doped into the Bi₂WO₆ nanosheets, the visible-light-driven photocatalytic oxygen evolution rate was increased up to 131.3 µmol·h⁻¹·g_cat⁻¹ under ambient conditions, which was more than 3 times that of pure Bi₂WO₆ nanosheets. The proper doping concentration of Fe could promote the formation of OVs and at the same time modulate the band structure of catalysts, especially the position of the valence band maximum (VBM), leading to effective visible-light absorption and enhanced oxidizing ability of photogenerated holes. With ameliorated localized electron distribution, fast charge transfer channel emerged between the OVs and adjacent metal atoms, which accelerated the charge carrier transfer and promoted the separation of photoexcited electrons and holes. This work provides feasible approaches for designing efficient two-dimensional semiconductor water oxidation photocatalysts that could utilize visible-light, which will make more use of solar energy.