Enhanced visible light photocatalysis and mechanism insight for novel Z-scheme MoS₂/Ag₂S/AgVO_x ternary heterostructure with fast interfacial charges transfer

A Z-scheme MoS₂/Ag₂S/AgVO_x ternary heterostructure was successfully synthesized by a facile hydrothermal method. The as-prepared MoS₂/Ag₂S/AgVO_x ternary composite has been characterized by electron microscopy, XRD, XPS, UV-Vis DRS, PL, electrochemistry and ESR. TEM characterization revealed that Ag₂S, Ag nanoparticles and AgVO_x nanorods were dispersed homogeneously over the surface of MoS₂ nanosheets The prepared heterojunction showed enhanced photocatalytic performance compared with single MoS₂ and AgVO_x. And 6%-MoS₂/Ag₂S/AgVO_x heterojunction exhibits highest photocatalytic degradation efficiency, which can degrade fuchsine around 75% under visible light within 180 min. The enhanced photocatalytic activity can be attributed to the efficient separation of photogenerated charge carriers, the strong redox ability and enhancement of visible-light absorption derived from the construction of Z-scheme heterostructure. In-situ formed metallic Ag₂S act as the electron mediator and Ag nanoparticles possess the surface plasmon resonance (SPR) effect. The prepared heterojunction showed decreased photoluminescence and increased photoelectrochemical performance, indicating high separation rate of photoinduced charge carriers. Furthermore, a possible degradation mechanism of fuchsine solution was proposed. And the results of radical trapping experiments indicated that superoxide radicals (∙O₂^-) and holes (h⁺) play major role during the photocatalytic degradation process. This work demonstrates an interesting Z-scheme photocatalytic system for photocatalysis applications.