Zinc Vanadate Modified Metal Chalcogenides Nanocomposites: Synthesis, Characterization and Photocatalytic Activity

Abstract

Organic contaminants from industrial or domestic effluents may be harmful to humans directly or indirectly by degrading the quality of environment. Consequently, these contaminants must be reduced to levels that are not harmful to humans and the environment before disposal. Chemical, physical and biological methods exist for the removal of these pollutants from effluents. Among the available chemical methods, heterogeneous photocatalytic oxidation has been found particularly effective in removing a large number of persistent organics in water. In this dissertation, the synthesis of Zn3V2O8 and metal chalcogenides for photocatalytic organic pollutant degradation is reported. UV active photocatalyst Zn3V2O8 was synthesized by co-precipitation method. However, it showed lower photocatalytic activity for dye degradation. In order to increase the light absorption spectral range and photocatalytic activity of Zn3V2O8, its heterostructures with metal chalcogenides (ZnSe and ZnTe) were synthesized. The photodegradation activity of Zn3V2O8/ZnSe, for congo red dye was investigated and the activity of Zn3V2O8/ZnTe will be determined in future. UV-Vis. photodegradation of dye over Zn3V2O8-ZnSe heterostructures showed 84.3% congo red degradation, when 75% of ZnSe was present in a composite. Bare ZnSe with both cubic and hexagonal phases showed 89.4% of congo red degradation under UV-Vis. light. The as-synthesized photocatalysts were characterized by different methods. Crystal structure, morphology, purity, composition and band gaps of photocatalysts and their heterostructures were studied by XRD, IR, SEM/EDX, and UV-Vis. DRS. Results for congo red degradation clearly indicate the anomalous behavior of bare ZnSe that showed higher activity than ZnSe heterostructure with Zn3V2O8.