A Ternary Ni Co Fe Nanoalloy-Based Oxygen Electrocatalyst for Highly Efficient Rechargeable Zinc-Air Batteries.

Replacing noble-metal-based oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) electrocatalysts is the key to developing efficient Zn-air batteries (ZABs). Here, a homogeneous ternary Ni Co Fe nanoalloy with a size distribution of 30-60 nm dispersed in a carbon matrix (denoted as C@NCF-900) as a highly efficient bifunctional electrocatalyst produced via supercritical reaction and subsequent heat treatment at 900 °C is reported. Among all the transition-metal-based electrocatalysts, the C@NCF-900 exhibits the highest ORR performance in terms of half-wave potential (0.93 V) in 0.1 m KOH. Moreover, C@NCF-900 exhibits negligible activity decay after 10 000 voltage cycles with minor reduction (0.006 V). In ZABs, C@NCF-900 outperforms the mixture of Pt/C 20 wt% and IrO , cycled over 100 h under 58% depth of discharge condition. Furthermore, density functional theory (DFT) calculations and in situ X-ray absorption spectroscopy strongly support the active sites and site-selective reaction as a plausible ORR/OER mechanism of C@NCF-900.