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

Abstract 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-C 3 N 4 /MoS 2 /Ag 3 PO 4 ternary composite and its application in photocatalytic oxygen evolution under white light LED illumination. As-exfoliated, highly conductive two-dimensional molybdenum disulfide (2D MoS 2 ) nanoflakes and modified graphitic carbon nitride (g-C 3 N 4 ) nanosheets were employed simultaneously to couple with oxygen-evolving silver orthophosphate (Ag 3 PO 4 ), forming a dual direct Z-scheme g-C 3 N 4 /MoS 2 /Ag 3 PO 4 (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 Ag 3 PO 4 . 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.