Effects of spin speed on the photoelectrochemical properties of Fe₂O₃ thin films

In this work, we report the effects of spin speed on structure and photoelectrochemical properties of Fe₂O₃ thin films. The Fe₂O₃ thin films were prepared by sol-gel method and spin coated on fluorine-tin-oxide coated glass substrate. The material properties were examined by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and optical spectroscopy. The photoelectrochemical characteristics were investigated at room temperature. It was demonstrated that heat treatment in air atmosphere greatly enhanced the XRD peak intensity and photocurrent density. Results of XRD show that α-Fe₂O₃ can be obtained using 500 °C annealing in air. The direct band gaps of the samples obtained from reflectance and transmittance spectra measurement are found to vary from 2.0 to 2.05 eV. The 5000-rpm sample has the maximum photocurrent density of 0.5 mA/cm² (at 0.5 V vs. Ag/AgCl) under a 300 W Xe lamp system. These good photoelectrochemical results and stability of the Fe₂O₃ thin film warrants further investigation for broader applications in the future.