Simple and large scale one-pot method for preparation of AgBr–ZnO nanocomposites as highly efficient visible light photocatalyst

Nanocomposites of AgBr–ZnO were successfully prepared in water by refluxing about at 90 °C for 3 h. In this method, zinc nitrate, silver nitrate, sodium bromide and sodium hydroxide were used as starting materials without using any additive and post preparation treatment. The nanocomposites were investigated by XRD, SEM, EDX, UV–vis DRS, and FT-IR techniques. In the nanocomposites, the ZnO has wurtzite hexagonal crystalline phase and loading of AgBr does not change its structure. The SEM images show that with increasing mole fraction of AgBr, surface morphology of the samples is changing to nanorods with smaller diameter. Photocatalytic activity of the nanocomposites was evaluated by degradation of methylene blue (MB) under visible light irradiation. The nanocomposites exhibit higher activity relative to the pure ZnO and AgBr. Among the prepared nanocomposites, the sample with 0.2372 mole fraction of AgBr exhibits highest photocatalytic activity. Moreover, influence of various operational parameters on the degradation reaction was studied and a possible degradation mechanism proposed. Chemical oxygen demand (COD) measurements were applied to check mineralization of MB on the nanocomposite under visible light irradiation.