New ternary mixed oxides of Fe, Ni and Mo for enhanced oxygen evolution

Ternary mixed oxides of Fe, Ni and Mo with molecular formulas Fe(x)Ni(1-x)MoO(4) (x = 0.25, 0.50 and 0.75) have been prepared by a co-precipitation method and investigated for their structural and electrocatalytic properties by XRD, AFM, electrochemical impedance spectroscopy and anodic Tafel polarization. Results indicate that the apparent oxygen evolution activity of the base (NiMoO(4)) electrode significantly increases with introduction of Fe from 0.25 to 0.75 mol. The Tafel slope for the oxygen evolution reaction at low overpotentials is found to be only similar to 35 mV on Fe-substituted oxides, while it was similar to 75 mV on the base oxide. The reaction follows the first order kinetics with respect to OH(-) concentration, regardless of Fe content in the oxide. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.