Deposition of ZnO Thin Films by Spray Coating Technique for Photocatalytic and Photochemical Degradation of Methylene Blue (MB)

Abstract

Deposition of a thin layer of Zinc Oxide (ZnO) on glass substrates by spray coating techniques has been done. ZnO is a semiconductor with band gap energy of ~ 3.2 eV and has the properties as oxidation photo catalysts that will transform harmful compounds and toxic substances in water into harmless compounds. ZnO thin film deposition is conducted by making gel ZnO with dissolving zinc acetate dehydrate (Zn(COOCH3)2.2H2O into a solution of isopropanol ((CH3)2CHOH) and monoethanolamine (MEA: HOCH2CH2NH2) at room temperature with a concentration of 0.3 M zinc acetate and the molar ratio is 1:1. ZnO gel is placed on the spray hole and sprayed on a glass substrate which has been heated at a temperature of 250°C at a pressure of 70 psi to form a thin layer. A thin layer is sintered at a temperature of 450°C for 2 hours. A ZnO thin layer then used as a photocatalytic and photochemical degradatioan of methylene blue (MB) with and without stirring. The microstructure analysis by using XRD show that the thin layers having polycrystalline wurtzite structure with orientations (100), (002), (101) and (110). EDS characterization showed that thin layers of ZnO consists of 50.27% and 49.73% zinc and oxygen atomic, respectively. ZnO photocatalyst reaction by using ultra violet light (UV) for 3 hours has been reduces the concentration of MB until 97.05%. A high percentage of color degradation MB performed by treatment with stirring.