Heterostructure NiCo-Alloy Nanosheet Embedded Ceria Nanorods: A Highly Efficient Bifunctional Electrocatalyst toward Oxygen Evolution Reaction and Oxygen Reduction Reaction: Energy and Fuels

The development of low-cost bifunctional electrocatalysts with high efficiency and comparable activity to the benchmark catalysts for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) is crucial to meet the practical demands of integrated water splitting and regenerative metal-air battery systems. In this study, a heterointerface structure of NiCo-alloy@CeO2 has been synthesized via a facile synthetic approach. NiCo-alloy nanosheets are rooted over the surface of the CeO2 nanorods, triggering an interfacial synergistic effect that significantly improves electrochemical performance. The resultant bifunctional electrocatalyst (NiCo-alloy@CeO2) demonstrates effective and enduring electrocatalytic ability toward OER and ORR in an alkaline environment. The catalyst exhibits a half-wave potential (E1/2) of 0.81 VRHE and onset potential (Eonset) of 0.89 VRHE for ORR in 0.1 M KOH. An overpotential (η) of 170 mV vs RHE at 20 mA cm-2 has been recorded for OER, which is superior to the ruthenium-based electrocatalysts. The low bifunctionality index (BI) of NiCo-alloy@CeO2 of ∼0.48 V indicates the ability of the synthesized material to be employed in metal-air batteries. This NiCo-alloy@CeO2 might be implemented in reliable and sustainable energy devices, paving the way for the design and fabrication of commercialized electrocatalysts, water splitting, and metal-air batteries. © 2023 American Chemical Society