Sonochemical preparation of AgBr–ZnO nanocomposites in water using one-pot method as highly efficient photocatalysts under visible light

Abstract

In the present article, we report a sonochemical one-pot method for the preparation of AgBr–ZnO nanocomposites in water without using any organic additives and post-preparation treatments. The X-ray diffraction patterns revealed that in the nanocomposites, ZnO and AgBr have wurtzite hexagonal and cubic crystalline phases, respectively. Scanning electron microscopy investigations showed that in the nanocomposites, particles of AgBr were distributed between ZnO nanostructures. Purity and chemical state of the elements were confirmed by energy-dispersive analysis of X-rays and X-ray photoelectron spectroscopy, respectively. UV–vis diffuse reflectance spectra showed that absorption ability in the visible range enhanced by increasing AgBr content of the nanocomposites. Visible light activities of the nanocomposites were investigated by degradation of methylene blue at 25 °C. The degradation rate constant on the nancomposite with 0.480 mol fraction of silver bromide is about 12.5-fold greater than for the ZnO nanostructures. Photoluminescence spectra of the samples revealed that the recombination rate of electron–hole pairs in the nanocomposite decreases relative to the pure ZnO. Moreover, the influence of ultrasonic irradiation time, catalyst weight, and pH of solution on the degradation rate constant was studied. Finally, the stability of the nanocomposite was tested for seven successive cycles.