Zn-Doped Fe2TiO5 Pseudobrookite-Based Photoanodes Grown by Aerosol-Assisted Chemical Vapor Deposition

Water splitting in photoelectrochemical cells is a promising technology to produce solar hydrogen. Fe2TiO5 pseudobrookite with a bandgap of around 2 eV absorbs the predominant visible range of the solar spectrum and is emerging as a promising photoanode for such cells. Herein, we present Fe2TiO5 pseudobrookite-based films prepared by aerosol-assisted chemical vapor deposition and the positive impact of Zn2+ doping in their formation and performance. Undoped and Zn2+-doped Fe2TiO5 pseudobrookite-based photoanodes were characterized by techniques such as XRD, XPS, UPS, and Mott-Schottky analysis. We find that the Zn2+ ions are preferentially incorporated in the pseudobrookite phase over a present secondary hematite (alpha-Fe2O3) phase. The Zn2+ doping modifies the electronic properties of the films, increases their charge carrier concentration, and upshifts their Fermi level, significantly improving their anodic photocurrent response by a factor of three. In addition, charge transfer efficiency calculations reveal that Zn2+ doping improves both charge separation and injection efficiencies, overall demonstrating a promising approach for the design of enhanced pseudobrookite-based photoanodes.