Energetic MOF-derived cobalt/iron nitrides embedded into N, S-codoped carbon nanotubes as superior bifunctional oxygen catalysts for Zn–air batteries

Abstract

Exploring highly effcient bifunctional oxygen catalysts is a central issue for rechargeable Zn–air batteries. Herein, bimetallic cobalt/iron nitrides in situ embedded into nitrogen, sulfur-codoped carbon nanotubes (CoN/FeN@N,S-C-800) was firstly developed by pyrolysis of a Fe-glucosamine coated tetrazole energetic metal − organic framework. Due to the significant nitrogen (5.38at%) dopant content, the synergistic effect between bimetallic nitrides, and interconnected N, S-codoped carbon nanotubes, the as-prepared CoN/FeN@N,S-C-800 exhibits an ultra-high half-wave potential (0.865 V) for oxygen reduction reaction (ORR) and a low overpotential (385 mV) for oxygen evolution reaction (OER). The assembled liquid Zn–air battery affords a high peak power density of 168.3 mW cm−2 and a low voltage gap of 0.55 V after 600 cycles (100 h). Impressively, an all-solid-state ZAB catalyzed by CoN/FeN@N,S-C-800 affords a high OCV of 1.354 V, and three all-solid-state ZABs in series can successfully light LED (~2.2 V), displaying tremendous potentials in portable devices.