Deposition of ZnO:Ag Photocatalyst Using Spray Coating Technique and Its Application for Methylene Blue and Methylene Orange Photodegradation

Abstract

ZnO:Ag thin films have been successfully deposited on glass substrates by spray coating technique with various Ag content of 2%, 3%, 4% and 5%. The ZnO:Ag thin films used to photodegrade the dye methyl orange and methylene blue using ultraviolet (UV) irradiation. ZnO:Ag solution was synthesized by dissolving zinc acetate dehydrate (ZnAc) in isopropanol then monoethanolamine (MEA) and Silver nitrate added into that solution at room temperature. The concentration of zinc acetate was 0.3 M and the molar ratio of MEA : ZnAc was 1:1. The solution was stirred by a magnetic stirrer at a temperature of 70°C for 30 minutes to obtain a clear and homogeneous solution. ZnO:Ag gel was sprayed on a glass substrate and then heated at temperature of 400oC for 15 minutes. Optical properties of ZnO:Ag thin films were characterized by using UV-Vis spectroscopy. The research showed that the incorporation Ag into ZnO can enhance photocatalytic activity due to the Ag depressed the recombination rate. In addition, the higher ion Ag concentration was decreased bandgap energy. The photocatalityc activity of ZnO:Ag could degraded methyl orange dye up to 42.68% for ZnO: Ag 4%, 45.45% for ZnO: Ag 5% and the degradation of methylene blue dye is reached up to 99.21% for ZnO:Ag 4% and the ZnO: Ag 5% thin films could degraded up to 100% under UV irradiation for 10 hours.