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

Abstract

A novel nanocomposite composed of two-dimensional graphene-like MoS₂ and Zn_xCd_1−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 Zn_xCd_1−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 Zn_xCd_1−xS are well dispersed and anchored on the surface of the graphene-like MoS₂ nanosheets. The superior interfacial coupling between Zn_xCd_1−xS and MoS₂ synergistically promoted the electron–hole transportation and separation. Upon visible-light irradiation (λ > 420 nm), the composite consisted of Zn_0.3Cd_0.7S and ca. 0.6 wt% graphene-like MoS₂ gave the highest hydrogen evolution amount of 7179.1 μmol g⁻¹, which is ca. 7 times as high as that of Zn_0.3Cd_0.7S. This study shows a facile method to build a low-cost but effective photocatalyst for water reduction to produce hydrogen under solar light irradiation.