In situ exsolved Co nanoparticles coupled on LiCoO2 nanofibers to induce oxygen electrocatalysis for rechargeable Zn–air batteries

Abstract

Layered lithium cobalt oxide, LiCoO₂ (LCO), is a promising catalyst for oxygen evolution reaction (OER) and oxygen reduction reaction (ORR); however, its bifunctional activity is still far from desirable. Here, a novel heterointerface of Co@LCO nanofibers (Co@LCO-NFs) is developed via an elegant in situ exsolution approach to promote bifunctionality. This in situ exsolution promises improved electrical conductivity, rich oxygen vacancies, and in particular a modulated electronic structure, thereby demonstrating a substantially enhanced bifunctional activity. Density functional theory calculations further reveal that the synergistic coupling of LCO and Co results in strengthened covalency of Co–O and facilitated OER/ORR kinetics. As a result, an assembled Zn–air battery using the Co@LCO-NFs electrode delivers high peak power density with competitive cycling stability, favorably outperforming the benchmark Pt/C–IrO₂ based batteries. This protocol provides new insights into designing heterostructured bifunctional catalysts for related energy conversion and storage devices.