Fabrication of dual direct Z-scheme g-C3N4/MoS2/Ag3PO4 photocatalyst and its oxygen evolution performance

Semiconductor-based photocatalytic materials have emerged as promising candidates for solar-driven hydrogen production and oxygen evolution reactions. Direct Z-scheme photocatalysts offer competitive advantages that are superior to single-component or intensively studied heterojunction photocatalysts in photocatalytic water splitting. The development of high-performance direct Z-scheme photocatalysts is crucial to improving solar-driven water splitting efficiency. Herein, we report the fabrication of a novel g-C₃N₄/MoS₂/Ag₃PO₄ ternary composite and its application in photocatalytic oxygen evolution under white light LED illumination. As-exfoliated, highly conductive two-dimensional molybdenum disulfide (2D MoS₂) nanoflakes and modified graphitic carbon nitride (g-C₃N₄) nanosheets were employed simultaneously to couple with oxygen-evolving silver orthophosphate (Ag₃PO₄), forming a dual direct Z-scheme g-C₃N₄/MoS₂/Ag₃PO₄ (CMA) composite photocatalytic system for highly improved oxygen evolution from water splitting. The optimal CAM-20 exhibits the fastest oxygen-producing rate of 232.1 μmol L^-1 g^-1 h^-1, which is 5 times higher than that of bulk Ag₃PO₄. The enhancement in the photocatalytic oxygen evolution can be ascribed to synergistic effects of improved visible light absorption, more efficient separation of photoexcited electron-hole pairs and a specific charge transfer pathway of tandem dual direct Z-scheme configuration under light illumination. This work paves the way for the construction of direct Z-scheme composite photocatalytic systems in water splitting.