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

A Z-scheme MoS2/Ag2S/AgVOx ternary heterostructure was successfully synthesized by a facile hydrothermal method. The as-prepared MoS2/Ag2S/AgVOx 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 AgVOx nanorods were dispersed homogeneously over the surface of MoS2 nanosheets The prepared heterojunction showed enhanced photocatalytic performance compared with single MoS2 and AgVOx. And 6%-MoS2/Ag2S/AgVOx 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.