Photo-electrochemical water splitting through graphene-based ZnS composites for H2 production

Abstract

Hydrogen production through photo-electrochemical (PEC) water splitting is obstructed by strong forces of attraction between H2O molecules and charge recombination in semiconductor materials. To overcome such limitations, graphene-based ZnS heterojunction photo-anode is developed that magnifies the PEC performance by improving optical properties and enhancing charge separation. ZnS composites with different weight ratios (2%, 4%, and 6%) of graphene are prepared through the hydrothermal process and characterized by using x-rays diffraction (XRD), transmission electron microscopy (TEM), uv–vis spectroscopy, and x-rays photon spectroscopy (XPS) to obtain crystallinity, morphology, uv–vis spectra and binding energy of prepared materials, respectively. Synergic effect of ZnS composite with 6% weight loading of graphene achieved a notable photo-current density (2.23 mA cm−2 at 0.72 V vs. RHE) under illumination. Moreover, 3.7 folds increased hydrogen yield of 0.049 μmoles cm−2 min−1 by 10 mg mass loading of material on fluorine-doped tin oxide (FTO) glass slide is obtained as compared to pure ZnS with hydrogen yield of 0.049 μmoles cm−2 min−1.