Combining ZnS with WS2 nanosheets to fabricate a broad-spectrum composite photocatalyst for hydrogen evolution

Abstract

With hydrogen storage methods advancing, “hydrogen economy” has been attracting considerable attention from scientists. It is therefore essential to develop efficient and stable methods for photocatalytic hydrogen evolution (PHE). Although some photocatalysts are highly efficient, they often contain noble or heavy metals, which are either expensive or not environmentally friendly. Therefore, fabricating economical and environmental-friendly photocatalysts is still a challenge. ZnS is an inefficient photocatalyst for hydrogen evolution due to its inability to absorb light at wavelengths longer than the ultraviolet range of the solar spectrum, a high recombination rate for photoinduced electron–holes, and photocorrosion as a result of photogenerated holes. WS₂ nanosheets are known as excellent cocatalysts. Herein, we report the first demonstration of ZnS/WS₂ nanosheet-composites (several layers) for use as economical and environmental-friendly photocatalysts. Combining ZnS with WS₂ nanosheets together can broaden the absorption spectrum and improve the electron–hole pairs separation efficiency. WS₂ nanosheets serve as an electron transporter, PHE activity sites, and also a ZnS nanoparticle immobilization scaffold in the composite. The PHE activity of ZnS/WS₂ nanocomposite is three times higher than that of pure ZnS nanoparticles under Xe lamp (300 W) irradiation, and the catalyst shows excellent photostability. The strategy presented in this study may have potential use in fabricating economical and environmental-friendly photocatalysts.