In-situ Construction of Oxygen Vacancies-Rich Direct Z-Scheme δ-Bi2O3/Bi2WO6 Heterojunction for Enhanced Photocatalytic N2 Fixation

Abstract

The recombination of interface charges hindered photocatalytic nitrogen fixation (NRR), but the introduction of surface oxygen defects (OV) and the construction of heterojunctions were found to effectively separate charges at the interface and enhance NRR efficiency. Here we successfully constructed the δ-Bi2O3/Bi2WO6 (BBWO-3) heterojunction with a core-shell similar structures and OV-rich via a solvothermal method, where the δ-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 μmol-1·g-1Cat under simulated sunlight, which was 6 times that of δ-Bi2O3 and 2.8 times that of Bi2WO6, without needing sacrificial agents. The enhanced photocatalysis activity was attributed to OV 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 δ-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 OV-rich core-shell similar structures direct Z-Scheme heterojunction photocatalysts.