Nonprecious Hybrid Metal Oxide for Bifunctional Oxygen Electrodes: Endorsing the Role of Interfaces in Electrocatalytic Enhancement

Abstract

The oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are considered as the core reactions in several alternative energy devices. Engineering the electronic structure of low-cost transition metal oxides (MOs) for the ORR and OER is highly demanding for such devices. Herein, a nonprecious mixed MO hybrid is reported that comprised of nanostructured Co3O4 and CeO2 supported on carbon (Co3O4–CeO2/C) with adequate oxygen vacancies and strong oxide/oxide and oxide/carbon heterointerfaces. The Co3O4–CeO2/C hybrid is highly active toward the ORR with values of the onset potential (−0.12 V) and Tafel slope (69 mV decade–1) comparable to that of benchmark Pt/C with a high limiting current density in alkaline medium. It can catalyze the OER efficiently at a less positive onset potential (0.23 V) and low Tafel slope (176 mV decade–1), in contrast with the standard RuO2 catalyst (0.45 V and 179 mV decade–1). The remarkable activity of the Co3O4–CeO2/C hybrid represents a promising route to replace noble metals and to develop low-cost bifunctional electrodes for energy devices.