Coupling ZnxCd1-xS nanoparticles with graphene-like MoS2: superior interfacial contact, low overpotential and enhanced photocatalytic activity under visible-light irradiation

A novel nanocomposite composed of two-dimensional graphene-like MoS2 and ZnxCd1-xS (0 <= x <= 0.5) nanoparticles has been synthesized by a simple exfoliation of bulk MoS2 into single-or few-layer MoS2 and then ultrasonic mixing of ZnxCd1-xS onto MoS2 nanosheets. The samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), high-resolution transmission electron microscopy (HRTEM), UV-visible diffuse reflectance spectroscopy (UV-vis DRS), photoelectrochemical experiments and photoluminescence spectroscopy. The results show that the nanoparticles of ZnxCd1-xS are well dispersed and anchored on the surface of the graphene-like MoS2 nanosheets. The superior interfacial coupling between ZnxCd1-xS and MoS2 synergistically promoted the electron-hole transportation and separation. Upon visible-light irradiation (lambda > 420 nm), the composite consisted of Zn0.3Cd0.7S and ca. 0.6 wt% graphene-like MoS2 gave the highest hydrogen evolution amount of 7179.1 mu mol g(-1), which is ca. 7 times as high as that of Zn0.3Cd0.7S. This study shows a facile method to build a low-cost but effective photocatalyst for water reduction to produce hydrogen under solar light irradiation.