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

A simple and cost-effective fabrication of the Zn-doped alpha-Fe2O3 thin film as a photocathode for solar hydrogen generation was proposed in this study. Transparent Zn-doped alpha-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 degrees C in air subsequently followed up. X-ray diffraction and Raman spectroscopic characterizations suggest the alpha-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. Xray photoelectron spectroscopic study otherwise demonstrates the substitution of Fe3+ for Zn2+ in the Zn-doped alpha-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 -0.1mA cm(-2) is delivered by the Zn-doped alpha-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. (C) 2018 Elsevier B.V. All rights reserved.