Selective growth of vertically aligned two-dimensional MoS2/WS2 nanosheets with decoration of Bi2S3 nanorods by microwave-assisted hydrothermal synthesis: Enhanced photo-and electrochemical performance for hydrogen evolution reaction

In this work, we fabricated MoS₂/WS₂ heterostrucutures with decoration of Bi₂S₃ nanorods through different stacking sequences (MoS₂/WS₂ (bottom layer) +Bi₂S₃ (top layer) and Bi₂S₃ (bottom layer) + MoS₂/WS₂ (top layer), respectively). The morphology and structure were studied by scanning electron microscope (SEM), transmission electron microscope (TEM) and the X-ray powder diffraction (XRD). It was found that the hybrid structure with different stacking sequences was composed of Bi₂S₃ nanorods and MoS₂/WS₂ nanosheets. By UV–visible absorption spectra (UV–vis) and photoluminescence (PL) experiments, we found that the composite catalysts of both stacking sequences can promote visible-light utilization and accelerate the electron transportation. Electrochemical measurements (such as cyclic voltammetry (CV), linear sweep voltammetry (LSV) and electrochemical impedance spectroscope (EIS) under light illumination or in dark) indicated that the MoS₂/WS₂+Bi₂S₃ possessed higher photoelectrocatalytic activity towards hydrogen evolution reaction (HER) than that of Bi₂S₃+MoS₂/WS₂ due to its proper energy band alignment that facilitates the effective carrier separation, the lower charge transfer resistance, higher electrochemically active surface area as well as the fast electron transfer kinetics. Inspired by these observations, we believe that MoS₂/WS₂+Bi₂S₃ catalyst is a potential candidate for photoelectrocatalytic production of H₂.