Photocatalytic hydrogen peroxide (H 2 O 2 ) production offers a sustainable alternative to the energy-intensive anthraquinone process. While metal oxides are promising catalysts, Al 2 O 3 is typically limited by its wide bandgap, insulating nature, and poor solar light absorption. This work introduces oxygen vacancies into mesoporous Al 2 O 3 via a facile NaBH 4 thermal treatment to dramatically enhance its photocatalytic performance. The defective Al 2 O 3 demonstrated excellent photocatalytic activity in both tetracycline degradation and H 2 O 2 production. The optimized mesoporous Al 2 O 3 -0.2, achieves an exceptional H 2 O 2 production rate of 2866 μmol g -1 h -1 under AM 1.5G, which is ∼2 times higher than that of pristine Al 2 O 3 . Comprehensive characterizations including density functional theory (DFT) calculations confirm the successful formation of oxygen vacancies, and the defect state reduces the bandgap from 5.27 to 3.49 eV, shifts the conduction band to a more negative potential (-0.81 V), and significantly improves charge separation and electron transfer efficiency. Mechanistic studies reveal that the reaction proceeds primarily via an oxygen reduction reaction (ORR) pathway, with superoxide radicals (·O 2 - ) acting as crucial intermediates. This study demonstrates that oxygen vacancy engineering is a highly effective strategy for activating wide-bandgap metal oxides like Al 2 O 3 for efficient solar-driven H 2 O 2 photosynthesis. • Oxygen vacancies are engineered in Al 2 O 3 via a facile thermal treatment. • The H 2 O 2 production rate is boosted 1.9-fold under light irradiation. • The H 2 O 2 formation was confirmed to proceed via oxygen reduction reaction.
Wang et al. (Sun,) studied this question.