Photo-Electrochemical Water Splitting through Graphene-Based ZnS Composites for H2 Production /

Abstract

Hydrogen is considered as a best fuel for the future. Clean and renewable energy sources are used to produce hydrogen which make it a clean and useful fuel. Nevertheless, most of hydrogen is produced from fossil fuels which contribute 95% in production of hydrogen whereas rest of 5% is produced from renewable or clean energy sources. Photo-electrochemical water splitting seems to be more competitive if we decrease the amount by advancing the technology. However, serious impacts on environment can be obtained by use of small bandgap semiconductor materials. Zinc Sulphide is one of the extensively studied photo-electrocatalysts under Ultraviolet illumination, it shows comparatively high activity for H2 production and under photoexcitation, it swiftly creates electron-hole pairs. It has a hexagonal structure. With significant surface area, it makes nanorods or nanosheets. Nonetheless, Because of its large band gap (3.6 eV) ZnS doesn’t show good results under visible illumination for excited electrons, still has a significantly negative potential. Struggles have been done to expand the optical absorption of ZnS into the visible region by doping it with transition-metal ions (Cu, Au, Ni,). To enhance the photocatalytic activity by improving charge separation and transfer coupling of two semiconductors is an established approach Photo-electrodes consist of composite materials provide functionally improved properties: 1) prevent the narrow-band-gap semiconductor from photo-corrosion, 2) enhance charge separation and suppress charge recombination, 3) extend the light absorption spectral range. Graphene can be used as co-catalyst because pf its stability towards photo-corrosion. Moreover, it can transfer electrons more efficiently to ZnS for Hydrogen production and by making it’s composite.