Preparation of LaMnO₃-CNF and Its Activity for Oxygen Electrode Reaction in 0.1 mol dm^-3 KOH Solution

Abstract

A composite catalyst (LaMnO 3 -CNF), containing LaMnO 3 and carbon nanofiber (CNF), was prepared by a co-precipitation method for use as a cathode catalyst in metal hydride (MH)/air battery. The catalytic activities for both the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) were investigated in aqueous KOH. The onset potential for the ORR of CNF and the composite catalyst was estimated to be 0.84 V and 0.91 V vs . a reversible hydrogen electrode (RHE), respectively. To estimate the onset potential for the OER, in-situ OER measurements were carried out using a dissolved oxygen sensor during chronoamperometry at the charging potential of a MH/air battery. The onset potential was found to be 1.65 V for CNF and 1.60 V for the composite catalyst.