Synergistic pyridinic-N/pyrrolic-N coordination tailors cobalt electronic states for high-efficiency oxygen reduction in Zn-air batteries

Abstract

Rational design of nitrogen-doped carbon-encapsulated transition metal catalysts with optimized interfacial compatibility and tunable electronic structures offers a promising route to develop cost-effective electrocatalysts for rechargeable Zn-air batteries (ZABs). However, the mechanism by which nitrogen configurations regulate the intrinsic activity of metal centers remains unclear. Herein, we develop N-doped carbon frameworks with a controllable pyridinic-N/pyrrolic-N ratio to modulate the coordination microenvironment of cobalt active sites. In situ characterization and theoretical calculations reveal a synergistic tandem mechanism between pyridinic-N and pyrrolic-N that enhances the oxygen reduction reaction (ORR). Remarkably, the optimized Co@N-C-750 electrocatalyst achieves a half-wave potential of 0.82 V in alkaline media. As an air cathode in ZABs, it delivers a peak power density of 127.7 mW cm⁻² and operates stably for >200 hours. This work provides fundamental insights for designing efficient transition metal electrocatalysts for advanced energy applications.