Nitrogen vacancy mediated g-C₃N₄/BiVO₄ Z-scheme heterostructure nanostructures for exceptional photocatalytic performance

In this work, a novel V_N-g-C₃N₄/BiVO₄ (V_N-CN/BVO) Z-scheme heterojunction photocatalyst was formed by introducing nitrogen vacancies (V_N) and constructing heterojunction, which is able to efficiently degrade the representative contaminant rhodamine B (RhB) upon exposure to visible-light, resulting in an outstanding degradation rate of 98.91% of RhB within 30 min. This photocatalyst exhibits catalytic universality and allows the degradation of methylene blue (MB, 97.59%) and tetracycline hydrochloride (TCH, 76.89%) within 100 min. The exceptional performances are attributed to the rational manipulation of nitrogen vacancy and Z-scheme heterojunction. Furthermore, the performance of the prepared photocatalysts in wastewater was investigated by photocatalytic degradation of TCH under different environmental conditions (cationic, anionic, and pH), and the synthesized V_N-CN/BVO photocatalysts exhibit excellent photocatalytic performance and stability. The decomposition products of TCH were further identified through liquid chromatography mass spectrometry and plausible decomposition routes were determined. This study demonstrates the importance of V_N-CN/BVO photocatalysts for the degradation of organic pollutants by photocatalysis under visible light. The Z-scheme heterostructure and synergistic effects endow the system with high-energy carrier transfer kinetics and strong oxygen reduction capability. Meanwhile, the surface nitrogen defects serve as electron acceptors to accelerate interfacial charge separation and as adsorption activation sites for organic pollutant molecules, promoting efficient mass transfer in the non-homogeneous system. This work may provide new ideas for the combination of defect engineering and heterojunction tactic for environmental remediation.