Highly active WO3–Ag–ZnO photocatalyst driven by day light illumination

Abstract

The WO3 loaded Ag–ZnO (WO3–Ag–ZnO) was successfully synthesized by precipitation–decomposition method. The catalyst was characterized by X-ray diffraction (XRD), field emission scanning electron microscope (FE-SEM) images, energy dispersive spectrum (EDS), transmission electron microscope (TEM), diffuse reflectance spectra (DRS), photoluminescence spectra (PL), cyclic voltammetry (CV) and BET surface area measurements. The photocatalytic activity of WO3–Ag–ZnO was investigated for the degradation of Naphthol Blue Black (NBB) in aqueous solution using solar light. WO3–Ag–ZnO is found to be more efficient than Ag–ZnO, WO3–ZnO, Ag–WO3, WO3, commercial ZnO, bare ZnO, TiO2–P25 and TiO2 (Merck) at pH 9 for the mineralization of NBB dye. The effects of operational parameters such as the amount of photocatalyst, dye concentration, initial pH on photo mineralization of NBB dye have been analyzed. The mineralization of NBB has been confirmed by Chemical Oxygen Demand (COD) measurements. A degradation mechanism is proposed for the degradation of NBB under solar light. This catalyst is found to be reusable.