Zn-Doped Fe<sub>2</sub>TiO<sub>5</sub> Pseudobrookite-Based Photoanodes Grown by Aerosol-Assisted Chemical Vapor Deposition
Miriam Regue, Ibbi Y. Ahmet, Prince Saurabh Bassi, Andrew L. Johnson, Sebastian Fiechter, Roel van de Krol, Fatwa F. Abdi, Salvador Eslava
Abstract
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 (α-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.