Role of N doping on the structural, optical and photocatalytic properties of the silver deposited ZnO thin films

In this study, nitrogen doped silver deposited ZnO (N-Ag/ZnO) thin films were successfully prepared at different rate flows of nitrogen via simultaneous co-sputtering of ZnO and Ag in the presence of varying nitrogen flow from 10 to 50 sccm by RF sputtering method. The role of N doping on the structural, optical and photocatalytic properties of the silver deposited ZnO thin films was studied. The deposited ZnO based thin films were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Field emission scanning electron microscopy (FESEM), Photoluminescence (PL), and UV-vis absorbance spectroscopy. The photocatalytic degradation efficiency of the prepared thin films was investigated for 2-cholorphenol (2-CP) in aqueous solutions under visible light irradiation. Results obtained revealed that varying the N flow rates resulted in control in the morphology, optical property and photocatalytic activity of the thin films. The particle size of the deposited metals reduced and become spherical as the flow rate of the nitrogen increased from 10 to 50 sccm. PL spectra shows that the N-Ag/ZnO thin has low intensity compared to the ZnO, Ag/ZnO thin films suggesting the effect separation of photogenerated electron/hole pairs, which results in the enhanced photocatalytic degradation of 2-CP. The results showed that N-Ag/ZnO (40N-Ag/ZnO > 50N-Ag/ZnO > 30N-Ag/ZnO > 20N-Ag/ZnO > 10N-Ag/ZnO) thin films have higher photocatalytic property compared to the pure ZnO, N-ZnO and Ag/ZnO thin films. The regeneration studies showed that after four regeneration cycles, ZnO based thin films are effective and no significant change in the photocatalytic degradation was observed. (C) 2016 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.