Effect of V substitution at B-site on the physicochemical and electrocatalytic properties of spinel-type NiFe2O4 towards O2 evolution in alkaline solutions ☆

Abstract Spinel-type ternary transition metal oxides of nickel, iron and vanadium with composition NiFe 2 − x V x O 4 (0 ≤  x  ≤ 1) have been synthesized by a hydroxide precipitation method and investigated for their physicochemical and electrochemical catalytic properties towards the oxygen evolution reaction (OER) in alkaline solutions at 25 °C. The OER study indicates that substitution of V from 0.25 to 1.0 mol for Fe in the spinel matrix increases the electrocatalytic activity of the oxide greatly; the activity being the greatest with x  = 0.5 mol. At low overpotentials, the Tafel slope and the order for the OER with respect to OH − concentration were found to be ∼40 mV and ∼2, respectively.