Effect of partial substitution of Cr on electrocatalytic properties of towards -evolution in alkaline medium

Some Cr-substituted manganese ferrites have been synthesized by a precipitation method in order to reduce the oxygen overpotential on the MnFe 2 O 4 surface. The study showed that Cr substitution from 0.1 to 1.0 mol considerably improved the electrocatalytic activity of the oxide for the oxygen evolution reaction (OER). Values of the Tafel slope and the order for the OER with respect to OH - concentration were ∼ 2 × 2.303 RT / 3 F and ∼ 2 and ∼ 2.303 RT / F and ∼ 1.5 at low and high over potentials, respectively.