Binary nickel and iron oxide modified Ti-doped hematite photoanode for enhanced photoelectrochemical water splitting

In this article, a novel and facile strategy to load low-cost and earth-abundant oxygen evolution catalyst NiFeOx by spin-coating on Ti-doped alpha-Fe2O3 films was reported. The NiFeOx modified hematite photoanode was prepared by a two-step process, which consisted of a hydrothermal method and a subsequent NiFeO(x)loading step. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and electrochemical impedance spectroscopy (EIS) were used to characterize the resulting photoanode. The highest photocurrent increment and lowest onset potential were observed with 30 mM NiFeOx precursor treatment. Increasing the loading content in a range from 10 to 90 mM, the photocurrent density increases from 0.998 for the pristine alpha-Fe2O3 to 1.126 mA/cm(2) at 1.23 V vs RHE (i.e., 12.7% increment) with 30 mM NiFeOx precursor treatment. Concomitant with this improvement was a cathode shift in the onset potential by nearly 55 mV and higher incident-photon-to-current efficiencies. Hematite photoanodes after NiFeOx deposition showed better performance than pristine samples, because of a lower overpotential for water oxidation resulted from NiFeOx modifying. Copyright (C) 2015, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.