Synthesis, characterization and catalytic activity of co-doped Ag–Au–ZnO for MB dye degradation under UV-A light

Abstract

The Ag loaded Au–ZnO was successfully synthesized by the precipitation–decomposition method. The catalyst was characterized by X-Ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FE-SEM), Energy Dispersive Spectrum (EDS), Transmission Electron Microscopy (TEM), Diffuse Reflectance Spectra (DRS), Photoluminescence spectra (PL) and BET surface area measurements. The photocatalytic activity of Ag–Au–ZnO was investigated for the degradation of Methylene Blue (MB) in aqueous solution using UV-A light. Ag–Au–ZnO is found to be more efficient than Ag–ZnO, Au–ZnO, commercial ZnO, bare ZnO, TiO2-P25 and TiO2 (Aldrich) at pH 7 for the mineralization of Methylene Blue dye. The effects of operational parameters such as the amount of photocatalyst, dye concentration, initial pH on photo mineralization of MB dye have been analyzed. The mineralization of MB has been confirmed by Chemical Oxygen Demand (COD) measurements. A mechanism is proposed for the degradation of MB under UV-A light.