Electrodeposition of a cobalt phosphide film for the enhanced photoelectrochemical water oxidation with α-Fe2O3 photoanode

The development of photoanodes capable of photoelectrochemical water splitting is a sustainable approach for the storage of solar power to conveniently useable chemical energy. In this study, we report that amorphous CoP film can be grown on α-Fe2O3 nanorods to fabricate a core-shell structure via a simple reductive electrodeposition strategy. Under the irradiation of simulated sunlight (100 mW cm−2), the composite electrode shows that the onset potential demonstrates a 200 mV cathodic shift and the photocurrent density is enhanced from 0.45 to 0.90 mA cm−2 at 1.23 V vs reversible hydrogen electrode (RHE) when compare with the bare α-Fe2O3 electrode in 1 M KOH electrolyte. Long-term photoelectrolysis reveals that this electrode has excellent stability and possesses a near-unity Faradaic efficiency toward oxygen evolution. Mechanistic studies support the role of CoP film in enhancing photoelectrochemical performance and indicate that the remarkable photoelectrochemical performance of this composite electrode is mainly due to the retardation of surface photogenerated h+/e− recombination.