Enhanced photocatalytic H 2 O 2 production through synergistic double-vacancy engineering in Z-scheme TiO 2-x /g-C 3 N 4-x heterojunction

The photocatalytic synthesis of hydrogen peroxide (H 2 O 2 ) is an environmentally benign and sustainable approach. In this study, we have synthesized a TiO 2-x /g-C 3 N 4-x (A-T x CN x ) photocatalyst with a Z-scheme heterojunction by introducing oxygen and nitrogen double vacancies through a one-step reduction process. The optimized A-T x CN x catalyst exhibited a superior H 2 O 2 yield of 1131.59 mu mol L -1 h- 1 under visible light, which is 5.85 times greater than that of the A-TCN catalyst. This enhancement is ascribed to the synergistic effects of the oxygen vacancies (Ov) and nitrogen vacancies (Nv) defects, which amplify light absorption, facilitate electronhole pair separation, and augment the number of active sites on the catalyst surface. Density functional theory (DFT) calculations and energy band analysis were employed to elucidate the photocatalytic mechanism of AT x CN x , revealing that H 2 O 2 synthesis predominantly occurs through two consecutive reactions, enabled by the catalyst 's unique electronic structure and defect configuration. This study not only validates the exceptional photocatalytic performance of A-T x CN x but also provides valuable insights for the design and optimization of future photocatalysts aimed at sustainable H 2 O 2 production.