Annealing temperature dependent catalytic water oxidation activity of iron oxyhydroxide thin films

Nanostructured iron oxyhydroxide (FeOOH) thin films have been synthesized using an electrodeposition method on a nickel foam (NF) substrate and effect of air annealing temperature on the catalytic performance is studied. The as-deposited and annealed thin films were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FE-SEM) and linear sweep voltammetry (LSV) to determine their structural, morphological, compositional and electrochemical properties, respectively. The as-deposited nanostructured amorphous FeOOH thin film is converted into a polycrystalline Fe2O3 with hematite crystal structure at a high temperature. The FeOOH thin film acts as an efficient electrocatalyst for the oxygen evolution reaction (OER) in an alkaline 1 M KOH electrolyte. The film annealed at 200 degrees C shows high catalytic activity with an onset overpotential of 240 mV with a smaller Tafel slope of 48 mV/dec. Additionally, it needs an overpotential of 290 mV to the drive the current density of 10 mA/cm(2) and shows good stability in the 1 M KOH electrolyte solution. (C) 2017 Science Press and Dalian Institute of Chemical Physics, Chinese Academy of Sciences. Published by Elsevier B.V. and Science Press. All rights reserved.