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 Sb 2 WO 6 /g-C 3 N 4 (SWO/CN) Z-scheme heterojunction fabricated by electrostatic self-assembly has better degradation activity than individual Sb 2 WO 6 and g-C 3 N 4 . The rate constant K (0.0194 min −1 ) of RhB degradation by 40 % SWO/CN was higher than that of Sb 2 WO 6 (0.0054 min −1 ) and g-C 3 N 4 (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-C 3 N 4 (0.1484 h −1 ) and Sb 2 WO 6 (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 ( 1 O₂) 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.