Crystalline Fe2O3/Fe2TiO5 heterojunction nanorods with efficient charge separation and hole injection as photoanode for solar water oxidation

We have constructed a Fe2O3/Fe2TiO5 heterojunction based photoanode deposited on Fluorine Doped Tin Oxide (FTO) substrate by initially fabricating hematite (Fe2O3) nanorods and subsequently pseudobrookite (Fe2TiO5) nanoporous thin film on top of them. Comparatively lower annealing temperature of 650 degrees C (usually 750 degrees C or above) was used to avoid degradation of FTO. The crystalline Fe2O3/Fe2TiO5 heterojunction shows a considerable enhancement in photocurrent density ca. 1.4 mA/cm(2) and high surface charge separation efficiency of 85% at operating voltage of 1.23 V vs RHE as compared to its constituents. The crystalline heterojunction showed overall improvement in performance due to enhanced charge separation owing to the favorable band alignment with Fe2O3 nanorods and efficient injection of photogenerated holes through surface states into the electrolyte observed through Electrochemical Impedance Spectroscopy. (C) 2016 Published by Elsevier Ltd.