CuCo-Embedded Nitrogen-Doped Carbon as a Bifunctional Catalyst for Efficient Rechargeable Zinc-Ethanol/Air Batteries

The oxygen evolution reaction (OER) in conventional zinc-air batteries (ZABs) involves a complex multielectron transfer process, leading to slow reaction kinetics, high charging voltage, and low energy efficiency. To address these limitations, a zinc-ethanol/air battery (ZEAB) system that strategically replaces the OER with the ethanol oxidation reaction (EOR) possessing a lower thermodynamic potential has been proposed. Herein, a bimetallic catalyst CuCo-embedded nitrogen-doped carbon (CuCo-20%-1), derived from a Cu/Co/Cd co-coordinated metal-organic precursor, is synthesized and exhibits an excellent performance for both EOR and ORR. A series of characterizations and in situ Raman spectroscopy analyses confirmed the formation of high-density M-Nx sites and Cu-doped CoOOH through an in situ electrochemical process from bimetallic CuCo species as the catalytic active sites for the oxygen reduction reaction (ORR) and EOR, respectively. Combined density functional theory calculations elucidated the catalytic reaction pathway and enhancement mechanism of Cu doping in CoOOH for EOR. The ZEAB system exhibits remarkable operational metrics, achieving an energy efficiency of 63.4%, representing a 32.7% energy consumption reduction compared to conventional ZABs. This strategic alternative model from the OER to EOR not only circumvents the fundamental kinetic limitations but also establishes a possible framework for promoting the practical application of next-generation metal-air battery technology.