In-situ construction of oxygen vacancies-rich direct Z-scheme -Bi₂O₃/Bi₂WO₆ heterojunction for enhanced photocatalytic N₂ fixation

The recombination of interface charges hindered photocatalytic nitrogen fixation (NRR), but the introduction of surface oxygen defects (O-V) and the construction of heterojunctions were found to effectively separate charges at the interface and enhance NRR efficiency. Here we successfully constructed the delta-Bi2O3/Bi2WO6 (BBWO-3) heterojunction with a core-shell similar structures and O-V-rich via a solvothermal method, where the delta-Bi2O3 nanosheets were grown in-situ on the surface of Bi2WO6 (BWO) hollow microspheres. The optimized BBWO-3 achieved a nitrogen fixation yield of 65.6 mu mol(-1)center dot g(Cat)(-1) under simulated sunlight, which was 6 times that of delta-Bi2O3 and 2.8 times that of Bi2WO6, without needing sacrificial agents. The enhanced photocatalysis activity was attributed to O-V and the formation of direct Z-Scheme heterojunction with core-shell similar structures, achieving effective spatial separation of photogenerated charges and providing a dedicated pathway for charge migration. At the meanwhile, since the bending of the band, an internal electric field (IEF) was formed from delta-Bi2O3 to BWO at the interface, which accelerate the dynamics of charge transfer. Moreover, the mechanism of the NRR was elucidated based on density functional theory (DFT) and in-situ XPS. This study provides a new idea for the construction of O-V-rich core-shell similar structures direct Z-Scheme heterojunction photocatalysts.