N and O vacancies regulation over semiconductor heterojunction to synergistically boost photocatalytic hydrogen peroxide production

Defect engineering represents a potent strategy for the modification of electronic properties by introducing atomic vacancies in photocatalysts. However, the synergistic enhancement attributable to different types of atomic vacancies within a heterojunction, as well as their underlying mechanisms, remains sparsely studied. Here, the flexible g-C3N4 materials with varying nitrogen vacancies were prepared via a facile calcination method under different atmospheric conditions and then composited with CeO2 nanocubes to construct Z-scheme heterojunction. It was observed that CeO2 has abundant O vacancies, and the g-C3N4 form tertiary nitrogen defects at the center of the heptazine units under an NH3 atmosphere treatment. The resulting enhancement in the interfacial built-in electric field, coupled with the synergistic effect of O and N vacancies within the Z-scheme heterojunction, has been demonstrated to significantly enhance charge transfer efficiency. This results in an optimized photoactivity with a H2O2 generation rate of 2.01 mmol g–1 h–1. This work opens an avenue for constructing and optimizing the heterogeneous photocatalysts by defect engineering technology, and provides deep insight to understand the nature of vacancy engineering in designing effective catalysts for solar energy conversion.