Fabrication of CoS/CdS heterojunctions for enhanced photocatalytic hydrogen production

Non-noble metal cocatalyst has showed good potential for improving photocatalytic hydrogen evolution reaction (HER). In this study, the non-precious metal cobalt sulfide (CoS) cocatalyst was deposited onto the CdS surface to construct heterojunctions using a solvothermal method. The fabricated structures were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), transmission electron microscopy (TEM), UV-visible diffuse-reflectance spectroscopy (UV-vis DRS), photoluminescence (PL), time-resolved PL spectra (TRPL) and photoelectrochemical measurements (PEC). The heterojunctions were evaluated as photocatalysts using the hydrogen evolution reaction with lactic acid as a sacrificial agent. The optimized 60 %-CoS/CdS sample shows a photocatalytic H-2 production rate of 3193.7 mu molmiddoth(-1)middotg(-1) under visible light (lambda >= 400 nm), which is 32 times higher than that of pure CdS. The improved performance is attributed to a great improvement in separation efficiency of the photogenerated electron-hole pairs.