Highly graphitized N-doped carbon nanosheets from 2-dimensional coordination polymers for efficient metal-air batteries

Abstract To meet the increasing energy demand, the research and development of efficient and clean fuel cells and metal-air batteries are of great significance. Under these circumstances, these hierarchically porous carbon nanomaterials obtained by pyrolysis of coordination polymers are regarded as excellent oxygen reduction catalysts and are expected to be used as air cathode materials. Herein, a type of 2-dimensional structure of InOF-26 has been thermally converted into ultrathin graphitized nitrogen-doped carbon nanosheets, denoted as NG-CNS. During the carbonization, the addition of ferric chloride assists in breaking the intermolecular forces between crystal structures, which is further conducive to the formation of carbon nanosheets with an improved graphitization degree. Meanwhile, the subsequent ammonia impregnation together with secondary calcination can readjust the coordination environment of nitrogen species in the carbonaceous matrix. The obtained product of NG-CNS exhibits excellent ORR performance with a high half-wave potential of 0.80 V, a large diffusion-limited current density of 6.00 mA cm−2, a small Tafel slope of 57.3 mV dec−1, to show unexpected practicability in Zn-air battery and Al-air battery. The relatively simple synthetic procedure, low cost, high repeatability, and satisfactory electrochemical performance of NG-CNS will provide a direction for the facile preparation of coordination polymer-derived carbon nanomaterials in energy storage and conversion applications.