Efficient photoelectrochemical water splitting using three dimensional urchin-like hematite nanostructure modified with reduced graphene oxide

Abstract

Herein, we present a highly photoactive photoanode for solar water oxidation using three dimensional (3D) urchin-like hematite (α-Fe2O3) nanostructures modified with ultra-thin reduced graphene oxide (rGO). rGO acts as both electron conducting scaffold and surface passivation layer. By virtue of these combined effects, the composite photoanode exhibits 1.47 times higher photocurrent density (1.06 mA cm−2, at 1.23 V vs. reversible hydrogen electrode (RHE)) and two-fold enhancement in the photoconversion efficiency than that of pristine α-Fe2O3. The dual effect of rGO as both electron conducting scaffold and surface passivation layer is further evidenced from the 1.82 and 1.67 fold enhancements in charge separation and charge injection efficiencies at 1.23 and 1 V vs. RHE respectively. To get further evidence about the origin of the improved photoactivity of the rGO modified photoanode, a series of electrochemical, photoelectrochemical and impedance spectroscopy measurements were carried out. Our results demonstrate the benefits of a noble metal free highly promising photoanode for photoelectrochemical water oxidation.