Soft-Pyrolysis Co-N-Implanted Polymer to Gain High-Density Co-Nx Sites on Carbons for Efficient Oxygen Reduction in Zn-Air Batteries

A soft-pyrolysis strategy by heating Co-N-implanted covalent organic polymer combining on carbon nanotubes at <= 500 degrees C has been developed to obtain efficient Co-N-C electrocatalysts for oxygen reduction reaction (ORR). The prepared Co-N-C is highly active for ORR with a half-wave potential of 0.91 V versus RHE in 0.1 m KOH electrolyte, superior to most of previously reported Co-based electrocatalysts. When employing it as cathode electrocatalyst, the homemade Zn-air battery shows a peak power density of 304.2 mW cm(-2), comparable to the parallel power density (250 mW cm(-2)) of Zn-air battery with Pt/C (20 wt%) electrocatalyst at cathode. The soft-pyrolysis strategy not only helps to generate high density Co-N-x active sites on carbons but also facilitates the optimizing balance between active site densities, graphitization degree, and pore structure of Co-N-C catalysts. Herein, a simple and energy-effective low-temperature pyrolysis strategy to obtain high-performance ORR electrocatalyst is provided.