Competitive Coordination-Oriented Monodispersed Cobalt Sites on a N-Rich Porous Carbon Microsphere Catalyst for High-Performance Zn-Air Batteries.

Abstract

Metal/nitrogen-doped carbon single-atom catalysts (M-N-C SACs) show excellent catalytic performance with a maximum atom utilization and customizable tunable electronic structure. However, precisely modulating the M-Nx coordination in M-N-C SACs remains a grand challenge. Here, we used a N-rich nucleobase coordination self-assembly strategy to precisely regulate the dispersion of metal atoms by controlling the metal ratio. Meanwhile, the elimination of Zn during pyrolysis produced porous carbon microspheres with a specific surface area of up to 1151 m2 g-1, allowing maximum exposure of Co-N4 sites and facilitating charge transport in the oxygen reduction reaction (ORR) process. Thereby, the monodispersed cobalt sites (Co-N4) in N-rich (18.49 at%) porous carbon microspheres (CoSA/N-PCMS) displayed excellent ORR activity under alkaline conditions. Simultaneously, the Zn-air battery (ZAB) assembled with CoSA/N-PCMS outperformed Pt/C+RuO2-based ZABs in terms of power density and capacity, proving that they have good prospects for practical application.