Development of tungsten disulfide ZnO nanohybrid photocatalyst for organic pollutants removal

In this study, ZnO and ZnO/WS₂ nanohybrid were synthesized by a facile microwave approach. Nanohybrid phase purity and structural features were examined through XRD, SEM–EDS, and EDS color mapping techniques. The optical absorbance and band gap energy of the ZnO/WS₂ nanohybrid was measured by the UV–DRS. Functional group features on the ZnO/WS₂ nanohybrid was investigated by the FT-IR spectroscopy. Further, the position of the conduction band and conductivity of the prepared ZnO/WS₂ nanohybrid was studied by the Mott–Schottky and Nyquist plot techniques. The photocatalytic properties of the ZnO/WS₂ nanohybrid were evaluated through the degradation of anionic and cationic organic pollutants such as methylene blue, bromophenol-B and 4-nitrophenol respectively. The organic pollutants degradation efficiency was determined by the UV absorbance spectroscopy and HPLC. Pseudo first order rate constant of the degradation reaction was calculated by the Langmuir–Hazelwood kinetic model. In addition, probe molecule mineralization was evaluated by TOC analysis. The ZnO/WS₂ nanohybrid catalysts durability was analyzed by subjecting it to four repeated photocatalytic cycles. After the photocatalysis reaction the catalyst structure distortion was analyzed by the XRD technique.