Visual Location of Oxygen Vacancies on Bismuth Titanate Nanosheets with Periodic Quantum Well and Promoting H₂O₂ Photosynthesis

Oxygen vacancy (OV) defect engineering plays a crucial role in enhancing photocatalytic efficiency. However, the direct visual characterization of oxygen vacancies still remains technically limited. Herein, a bismuth titanate (Bi₄Ti₃O₁₂, BTO-OV) model photocatalyst containing oxygen vacancies is constructed through density functional theory (DFT) calculations to reveal the influence mechanism of distinctive periodic quantum well and oxygen vacancies on the charge transfer behavior in BTO. Notably, the distribution of oxygen vacancies is directly observed using the low-dose integrated differential phase contrast-scanning transmission electron microscopy (iDPC-STEM), providing visual evidence for the location of these oxygen vacancies in BTO-OV. Furthermore, the theoretical calculation results are verified by characterizing the photoelectric properties and conducting performance tests on the hydrogen peroxide (H₂O₂) photosynthesis. Specifically, the oxygen vacancies and distinctive periodic quantum well in BTO-OV accelerate charge separation, leading to a H₂O₂ photosynthesis efficiency reaching 5278 µm g^-1 h^-1, which is 5 times that of the original BTO. This work offers theoretical and experimental references for the visual characterization of oxygen vacancies and the improvement of the charge transfer mechanism.