FeCo nanoalloy embedded in N-doped carbon aerogel as high-efficiency oxygen electrocatalyst for long-term zinc-air batteries

Abstract

Bifunctional oxygen electrocatalysts with low cost and high catalytic activity are critically important for improving the energy conversion efficiency of metal-air batteries. In this work, a novel electrocatalyst, denoted as NC-Fe_xCo_y, was synthesized via the growth of Fe-ZIF-67 on the surface of a chitosan-derived aerogel, followed by subsequent annealing treatment. The adjustable pore structure of the chitosan-derived carbon aerogel facilitates enhanced availability of active sites. Moreover, the synergistic interplay between the FeCo nanoalloy and the nitrogen-doped carbon framework further augments its catalytic performance. As expected, the optimized catalyst NC-Fe₁Co₃ exhibits exceptional bifunctional electrocatalytic activity, achieving a half-wave potential of 0.88 V for the oxygen reduction reaction (ORR) and an overpotential of only 378 mV for the oxygen evolution reaction (OER). Furthermore, the assembled liquid ZABs employing the NC-Fe₁Co₃ as air cathode demonstrated outstanding performance, delivering a remarkable power density of 240 mW cm⁻² and long-time charge-discharge stability over 2000 h. Additionally, the flexible ZABs fabricated with this catalyst achieved an even higher power density of 116 mW cm⁻², coupled with a robust cycle stability lasting over 200 h.