Novel ZnO/Ag₂CrO₄ nanocomposites with n–n heterojunctions as excellent photocatalysts for degradation of different pollutants under visible light

Novel ZnO/Ag₂CrO₄ nanocomposites, as excellent visible-light-driven photocatalysts, were successfully prepared with different weight percents of Ag₂CrO₄ using a facile refluxing method at 96 °C. The phase, purity, morphology, and electronic properties of the resultant samples were characterized using XRD, EDX, SEM, TEM, UV–Vis DRS, FT-IR, and PL techniques. The nanocomposite with 30 % of Ag₂CrO₄ was selected as the best photocatalyst for degradation of rhodamine B under visible-light irradiation. Activity of this nanocomposite is about 16-, 20-, and 25-fold greater than that of the ZnO in degradation of rhodamine B, methylene blue, and methyl orange, respectively. The excellent activity of the nanocomposites was attributed to more visible-light absorption ability, due to presence of narrow band gap Ag₂CrO₄, and fast separation of the photogenerated charge carriers, due to formation of n–n heterojunctions between ZnO and Ag₂CrO₄. Furthermore, the influence of preparation time, calcination temperature, and scavengers of the reactive species on the photocatalytic activity was studied and the results were discussed.