Cu-doped flower-like hematite nanostructures for efficient water splitting applications

• Flower-like Cu-doped hematite nanostructures on FTO glass substrates were prepared.
• The prepared nanostructures were applied for water splitting experiments.
• Cu-doping results in an enhancement of the hematite's water splitting performance.

This study reports the successful preparation of Cu-doped hematite (α-Fe2O3) flower-like nanostructures with different Cu concentrations on FTO glass substrates using a facile hydrothermal method. The Cu-doped α-Fe2O3 flower-like nanostructure combines the advantage of p-type doping with the feature of a flower-like architecture. The prepared nanostructure film was applied as a photocathode in a photoelectrochemical (PEC) water splitting experiment and achieved a significantly improved photocurrent density of −5.34 mA cm−2 at −0.6 V vs. reversible hydrogen electrode (RHE) for 1 mol% Cu doping. The obtained photocurrent is about 4.85 times higher than that of the pure α-Fe2O3 based photoelectrode. The incorporation of Cu into α-Fe2O3 results in a dramatic enhancement in the water splitting performance. The enhancement is gained through an improvement in light harvesting and charge carrier separation. The copper-modified α-Fe2O3 sample also exhibited an up shift in the conduction band edge potential, which is energetically favorable for the water reduction reaction. This result demonstrated high performance PEC water splitting as a potential route for the production of hydrogen gas using a single Cu-doped α-Fe2O3 photoelectrode without the need for other catalysts and hybrid structures.