CoN nanoparticles anchored on ultra-thin N-doped graphene as the oxygen reduction electrocatalyst for highly stable zinc-air batteries

Transition metal nitrides anchored on carbon as oxygen reduction catalysts are widely used in zinc-air batteries. However, the size of transition metal nitrides and the thickness of carbon substrate are often difficultly controlled. Herein, the CoN nanoparticle anchored on ultra-thin nitrogen-doped graphene electrocatalyst (CoN/UNG) was synthesized by the combination strategy of the coordination of 1, 10-phenanthroline with the intercalation effect of polyethylene imine. Polyethylene imine can intercalate into layers of graphene and block the heaping of graphene to achieve ultra-thin nanosheet structures. Lone-pair electrons on nitrogen atoms of 1, 10-phenanthroline can bond to Co2+ to form the Co-N coordination, then confine the aggregation of Co atoms. Finally, small-sized CoN nanoparticles were successfully anchored on ultra-thin nitrogen-doped graphene. The CoN/UNG has a half-wave potential of 0.87 V vs. RHE with excellent electrochemical ORR performance and high stability. The power density of CoN/UNG-based zinc-air battery is 149.3 mW cm(-2); the specific capacity is 917.2 mAh g(-1) and the cycle stability is 350 h. The new combination strategy is conducive to the rational design of small-sized transition metal nitrides anchored ultra-thin nitrogen-doped graphene catalysts to boost the application of zinc-air batteries.

Automated summary

In this study, small-sized transition metal nitrides anchored on ultra-thin nitrogen-doped graphene were successfully synthesized using a combination strategy. The resulting CoN/UNG catalyst exhibited excellent electrochemical performance for oxygen reduction reaction (ORR) with high stability. This research provides a new approach for the rational design of catalysts in zinc-air batteries.