The influence of the hydrothermal temperature and time on morphology and photoelectrochemical response of α-Fe2O3 photoanode

Abstract

By controlling the aging temperature and time, α-Fe2O3 photoanodes with different morphology are successfully prepared, such as nanorod and nanocolumn. High-aligned α-Fe2O3 nanorods photoanodes were prepared by hydrothermal method under lower aging temperature and medium aging time without Ostwald bending to obtain the optimal photoanode for photoelectrochemical water oxidation under solar light. The morphology, optical properties, photoelectrochemical response and charge transfer of the α-Fe2O3 photoanodes were investigated by X-Ray diffraction (XRD), UV–vis absorbance spectroscopy, scanning electron microscopy (SEM), Mott−Schottky (MS) and electrochemical impedance spectroscopy (EIS). The optimal α-Fe2O3 nanorods photoanode with 100 nm in diameter and 300 nm in thickness could be obtained under 95 °C for 5 h, which have the optimal photocurrent density up to 0.54 mA cm−2 at 1.23 V (vs. RHE.) and 0.12 V negative shift in the onset potential of photocurrent compared with nanocolumns photoanodes. As revealed by EIS analysis, the enhanced photoelectrochemical response is mainly attributed to the decreased resistance of charge transfer inside the nanorods electrode and across the interface between electrode and electrolyte. This work provide an in-depth understanding of the relationship between hydrothermal synthesis process, morphology, crystalline structure and photoelectrochemical performance of α-Fe2O3 photoanode via systematically studied the photoanode prepared by hydrothermal method.