The electrocatalytic activity of Ni(II)/Ni(III) oxide films in alkaline solutions

Abstract

The reactions involved in the electroreduction and electroformation of O 2 on electrodes prepared by precipitation of nickel hydroxide on different conducting substrates (platinum or vitreous carbon) in alkaline solutions are investigated. The catalytic activity of these electrodes for the O 2 evolution reaction is independent of the nature of the substrate but depends on the ageing conditions of nickel hydroxide. The mechanisms for the O 2 evolution reaction are explained through the participation of both Ni(III) and very reactive Ni(IV) species. The electrocatalytic activity is related to the u-NiOOH species. The O 2 electroreduction occurs on the substrate surface and is mainly determined by the characteristic of the substrate.