Electrochemical degradation of methyl red in zinc hydroxide and zinc oxide thin films, physical and chemical activation

Abstract

The experimental and ab initio results on structural, optical, and electronic properties of Zn(OH)2 and ZnO thin films (TFs) at various annealing temperatures are reported. The as-grown TF consists of Zn(OH)2 while annealing them at temperatures higher than 300 °C yields high-quality ZnO. The films were highly crystallized in a hexagonal structure with (200) orientation by XRD analysis. The evaluated optical band gap energies of Zn(OH)2 and ZnO TFs were 3.955 and 3.286 eV, respectively, and agree well with Vienna ab initio hybrid functional HSE06 density of states calculations. The material activation of ZnO and Zn(OH)2 TFs in electrochemical degradation catalyses of methyl red in water proven that ZnO TFs have higher decolourization efficiency than Zn(OH)2 TFs. The electrochemical circuit used was performed under experimental conditions of 12 V voltage difference and 0.3 A current.