Heteroatom functionalized double-layer carbon nanocages as highly efficient oxygen electrocatalyst for Zn-Air batteries

Abstract

The nonprecious electrocatalyst with high electrocatalytic activity and low cost is urgently desired to fulfill the demands of efficient rechargeable Zn-air batteries (ZABs). Herein, the heteroatom functional carbon-based nanocage Zn-NC is prepared through pyrolysis of ZIF-8. In this process, the organic ligands are converted into partially graphitized carbon with simultaneously reduction of Zn2+ to metal Zn, thus the nitrogen doping porous structure and homogeneous distributed zinc endow the Zn-NC more exposed active surface. Further co-heat treatment of carbonized ZIF-8 precursor with dicyandiamide and glucose results in the formation of Zn, N atomic-level modified carbon material Zn-NC/GD. The dual-shell carbon nanocage structure produces obvious interface properties, which can well bind the escaping metallic zinc to form Zn–N–C bond structure. Benefiting from double carbon modification, interfacial properties, and bonding structure, the Zn-NC/GD performs outstanding half-wave potential (0.86 V) and a lower Tafel slope (97.8 mV dec−1). Consequently, as an air electrode, the Zn-NC/GD also exhibits high open circuit voltage (1.531 V), remarkable power density (326.1 mW cm−2), and excellent specific capacity (824.7 mAh gzn−1). The critical findings demonstrate promising potential to obtain an efficient atomic-level modification of carbon-based electrocatalyst for ZABs.