Co-Nx-enriched porous carbon nanofibers as efficient oxygen electrocatalyst for flexible Zn-air batteries

An efficient, robust and low-cost bifunctional electrocatalyst for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is essential to high-performance zinc-air batteries (ZABs). Metal-nitrogen-carbon (M-N-C) systems have attracted considerable attention recently. Herein, a novel Co-Nx-enriched electrospun porous carbon nanofibrous bifunctional electrocatalyst (Co-Nx/EPCF) is prepared by electrospinning with cobalt nitrate and SiO2, followed by carbonization and acid etching. The catalyst displays an outstanding electrocatalytic activity of reversible oxygen overpotential (ΔE = Ej = 10 - E1/2 = 0.87 V), as well as a high stability. The first-principal calculation reveals that the Co–N–C structure has better ORR paths than that of Co cluster. Furthermore, based on the electrocatalyst, the assembled flexible ZABs possess a power density of 81 mW cm−2, a capacity of 807 mAh gzn−1, and 111 stability cycles. The study provides a novel strategy to prepare high-performance bifunctional catalysts for wearable power sources.