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

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 Zn 2+ 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 g zn −1 ). The critical findings demonstrate promising potential to obtain an efficient atomic-level modification of carbon-based electrocatalyst for ZABs.