Structural and optical properties of Fe- doped ZnO thin films prepared by Sol–Gel spin coating process and their photocatalytic activities

Abstract

Pure and Fe-doped zinc oxide nanocrystalline films were prepared via a sol–gel method using spin coating process. Pure and Fe-doped zinc oxide, containing 2 to 8 % Fe, were annealed at 500 ̊C for 2 h. The thin films were prepared and characterized by X-ray diffraction (XRD), atomic force microscopy (AFM), field emission scanning electron microscopy (FE-SEM) and UV- visible spectroscopy. The XRD results showed that ZnO has hexagonal wurtzite structure and the Fe ions were well incorporated into the ZnO structure. As the Fe level increased from 2 wt% to 8 wt%, the crystallite size reduced in comparison with the pure ZnO. The transmittance spectra were then recorded at wavelengths ranging from 300 nm to 1000 nm. The optical band gap energy of spin-coated films also decreased as Fe doping concentration increased. In particular, their optical band gap energies were 3.75, 3.6, 3.5, 3.45 and 3.3 eV doping concentration of 0%, 2%, 4%, 6% and 8% Fe, respectively. The performance of the pure and doped ZnO thin films was examined for the photocatalytic activity using organic dyes (methyl orange, methyl blue, methyl violet). The samples ZnO with concentration of Fe showed increased photocatalytic activity with an optimal maximum performance at 0.8 wt%.