Enhanced photoelectrochemical water oxidation in Hematite: Accelerated charge separation with Co doping

Abstract Hematite (α-Fe2O3) is one of the most promising candidates for a photoanode for photoelectrochemical water splitting. However, it has low efficiency because of poor conductivity in the bulk and sluggish oxygen evolution (OER) kinetics on the surface. In this study, a Co-doped α-Fe2O3 photoanode was prepared by the hydrothermal method. It had increased charge separation efficiency and accelerated surface reaction kinetics simultaneously. At the optimal Co content, the photocurrent density of the Co-doped α-Fe2O3 increased by 23 times to 0.54 mA/cm2 at 1.23 VRHE in 1 M NaOH electrolyte; this increase was attributed to the improvement in carrier density and charge transfer behavior. Moreover, the cathodic shift of onset potential for Co-doped α-Fe2O3 reached 290 mV owing to the accelerated OER kinetics. This work reveals the key roles of Co doping and provides a suitable photoanode for solar hydrogen technology.