Facile preparation of Zn-doped hematite thin film as photocathode for solar hydrogen generation

Abstract

A simple and cost-effective fabrication of the Zn-doped α-Fe2O3 thin film as a photocathode for solar hydrogen generation was proposed in this study. Transparent Zn-doped α-Fe2O3 films were prepared by a spin-coating process using nontoxic iron chloride as the iron precursor and zinc chloride as an acceptor dopant, and the thermal treatment at 550 °C in air subsequently followed up. X-ray diffraction and Raman spectroscopic characterizations suggest the α-phase to the Zn-doped hematite film, indicating that the incorporation of Zn into the Fe2O3 host lattice is carried out in the absence of phase transition. X-ray photoelectron spectroscopic study otherwise demonstrates the substitution of Fe3+ for Zn2+ in the Zn-doped α-Fe2O3 specimens. Mott-Schottky analysis shows that the Zn dopant functions as the hole acceptor and the carrier density is dictated by the concentration of the zinc precursor. Significantly, a notable cathodic photocurrent of −0.1 mA cm−2 is delivered by the Zn-doped α-Fe2O3 photocathode with a doping level of 10% in the photoelectrochemical measurement. Last but not least, the doping effect on the photo-activity of hematite is systematically investigated that in turn works as the blueprint for materials design in the solar application.