β-Ag2S–ZnO as a novel sunshine photocatalyst for the effective degradation of RR 120 dye

Abstract

A novel β-Ag2S loaded ZnO was successfully synthesized by precipitation of zinc oxalate and Ag2S and calcination of the mixed precipitate at 400 °C for 12 h. The catalyst was characterized by XRD, FE-SEM, EDS, TEM, DRS, PL, CV, XPS and BET surface area measurements. XPS reveals that Ag in the catalyst is present in the form of Ag+ before irradiation. The photocatalytic activity of β-Ag2S–ZnO was investigated for the degradation of RR 120 under solar light. It is found to be more efficient than commercial ZnO, prepared ZnO, TiO2-P25 and TiO2 (Merck) at neutral pH for the mineralization of RR 120. The effects of operational parameters have been analyzed, and the mineralization of RR 120 has been confirmed by COD measurements. The catalyst is found to be reusable. A dual mechanism involving dye sensitization has been proposed for the degradation of RR 120 by β-Ag2S–ZnO under day light illumination.