GREEN SYNTHESIS OF ZnS THIN FILMS BY CHEMICAL BATH DEPOSITION

Semiconducting zinc sulphide (ZnS) has been demonstrated that is an excellent candidate for substituting the possible toxic materials as CdS as n-type material on optoelectronic devices, and photocatalytic materials. The Chemical Bath Deposition technique (CBD) is very simple: it requires temperatures below 100°C, a reactor that can be a beaker and the reaction can be carried out at atmospheric pressure. This study report a simple and green route for coating ZnS thin films onto glass-slide substrates by the CBD method, without the use of any complexing agents. Effects of vacuum annealing at various temperatures on the optical, structural and photocatalytic properties of nanocrystalline ZnS thin films were investigated. The ZnS thin films were prepared by a simple, economical and green synthesis, avoiding the use of any high-toxicity complexing agents. The chemical-bathprepared ZnS thin films were obtained at 65°C on glass substrates. The band gap of the films varied in the range 3.28 to 3.64 eV. The photocatalytic activity of the ZnS thin films was evaluated by employing the degradation of aqueous methylene blue solution at a concentration of 2 × 10 −5 mol L −1 . The ZnS thin-film sample annealed in a vacuum atmosphere at 200°C exhibited the highest photocatalytic activity.