Enhancement of photocatalytic activity of 2D/2D Sb₂WO₆/g-C₃N₄ Z-scheme heterojunction via effective interfacial charge transfer

A Z-scheme heterojunction is designed and demonstrated to enhance the separation efficiency of photocatalytic carriers. In this paper, the 2D/2D Sb₂WO₆/g-C₃N₄ (SWO/CN) Z-scheme heterojunction fabricated by electrostatic self-assembly has better degradation activity than individual Sb₂WO₆ and g-C₃N₄. The rate constant K (0.0194 min⁻¹) of RhB degradation by 40 % SWO/CN was higher than that of Sb₂WO₆ (0.0054 min⁻¹) and g-C₃N₄ (0.0039 min⁻¹). The rate constant K of 40 % SWO/CN for MBT degradation was 0.4391 h⁻¹, which was 2.96 and 9.32 times that of g-C₃N₄ (0.1484 h⁻¹) and Sb₂WO₆ (0.0471 h⁻¹). The photocurrent response and electrochemical impedance spectroscopy (EIS) reveal that the Z-scheme heterojunction facilitates the separation of photogenerated charge carriers. Electron spin resonance (ESR) and radical trapping experiments demonstrate the pivotal roles of holes (h⁺), superoxide (·O₂^-), and singlet oxygen (¹O₂) in the catalytic degradation process. The results provide insights into the design of high-performance 2D/2D Z-scheme photocatalysts and a fundamental framework for further enhancement. © 2025 Elsevier B.V.