Enhanced photocatalytic H2O2 production through synergistic double-vacancy engineering in Z-scheme TiO2-x/g-C3N4-x heterojunction

Abstract

The photocatalytic synthesis of hydrogen peroxide (H2O2) is an environmentally benign and sustainable approach. In this study, we have synthesized a TiO2-x/g-C3N4-x(A-TxCNx) photocatalyst with a Z-scheme heterojunction by introducing oxygen and nitrogen double vacancies through a one-step reduction process. The optimized A-TxCNx catalyst exhibited a superior H2O2 yield of 1131.59 μmol L–1h−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 electron-hole 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 A-TxCNx, revealing that H2O2 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-TxCNx but also provides valuable insights for the design and optimization of future photocatalysts aimed at sustainable H2O2 production.