Abstract
Abstract Here we introduce a facile synthesis of carbon-coated hematite nanostructures for solar water splitting via a simple electrochemical methods. This is the first time the synthesis of carbon-coated hematite being reported via electrodeposition. We investigate the structure and photoelectrochemical effects of adding citric acid as carbon source to synthesize nanostructured α-Fe2O3 thin films. Firstly, we know that the chelation between ferric ions and citric acid significantly changes the distribution of ferric species in comparison with that without any citric acid additives. The addition of citric acid greatly enhanced the photocurrent when the electrodeposition was conducted in the alkaline environment. The data of XPS clearly shows a strong C signal appearing at 284 eV, which is in a good agreement with the TEM results. The photocurrent of carbon-coated hematite films obtained from cit-Fe system increases with increasing pH, reaching a maximum photocurrent around 2.1 mA at pH 8. Electrochemical impedance spectroscopy revealed that C doped films have higher donor density than that of undoped film,which is responsible for high photoactivity. The simple and cheap method could be scaled up easily which may pave the way for the practical application for efficient solar water splitting.