Supersonically sprayed iron oxide nanoparticles with atomic-layer-deposited ZnO/TiO2 layers for solar water splitting

Abstract

We demonstrate a promising Fe2O3/ZnO/TiO2 photoanode for photoelectrochemical water splitting. Passivation of the Fe2O3 surface with thin layers of ZnO and TiO2 enhances the water splitting photocurrent density of Fe2O3. The increased photoelectrochemical activity of the hematite-based structure with heterojunctions, compared to that of bare Fe2O3, results from improved charge separation during water oxidation. The multilayered Fe2O3 film exhibits a seven-fold improvement in photocurrent density (to 4.25 mA cm(-2)) compared with bare Fe2O3, due to suppression of electron-hole recombination. The transient photocurrent density and impedance were evaluated to assess the effect of the passivation layer thickness and achieve a high photocurrent at low potential (0.7 V vs. Ag/AgCl) through improved light harvesting of the Fe2O3 film with an ultrathin ZnO/TiO2 overlayer. (C) 2019 Elsevier B.V. All rights reserved.