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-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.