Coherent Design of ZnO_0.5S_0.5/g-C₃N₄ Nanoheterostructures: Efficient Photocatalysts for H₂ Generation

The development of nanostructured heterojunction catalysts has great potential to improve the photocatalytic H2 generation performance. In this regard, ZnO0.5S0.5/g-C3N4 (ZnOS/g-CN) semiconductor nanoheterostructures based on ZnO0.5S0.5 and g-C3N4 were designed through a simple method by deposition of different concentrations of ZnOS ranging from 10 to 50 wt % on graphitic carbon nitride (g-CN) nanosheets at 140 °C. The formation of the ZnOS/g-CN nanoheterostructures was confirmed via powder X-ray diffraction and supported by X-ray photoelectron spectroscopy (XPS) analysis. Field-emission scanning electron microscopy (FESEM) indicated the formation of a composite-type structure having two types of morphologies. ZnOS with distorted spherical particles were evenly deposited on the surface of g-CN sheets. Field-emission transmission electron microscopy (FETEM) and high-resolution transmission electron microscopy (HRTEM) confirmed the existence of heterostructures of ZnOS and g-CN. The absorption spectra clearly showed the distinct band gaps of ZnOS and g-CN in the nanoheterostructures. The surface area of samples was measured by the Brunauer–Emmett–Teller (BET) technique, and 50 wt % ZnOS/g-CN was found to have a large surface area (36.20 m2 g–1) among all of the prepared compositions. Furthermore, the premier composition indicated high photocatalytic H2 generation around 920.4 μmol of hydrogen per 0.1 g of catalyst via water splitting under 4 h of irradiation. The effective separation of photogenerated charge carriers due to the formation of nanoheterostructures of ZnOS/g-CN led to higher H2 generation.