Core-shell-structured Co@Co4N nanoparticles encapsulated into MnO-modified porous N-doping carbon nanocubes as bifunctional catalysts for rechargeable Zn–air batteries

Designing the highly catalytic activity and durable bifunctional catalysts toward oxygen reduction/evolution reaction (ORR/OER) is paramount for metal–air batteries . Metal–organic frameworks (MOFs)-based materials have attracted a great deal of attention as the potential candidate for effectively catalyzing ORR/OER due to their adjustable composition and porous structure . Herein, we first introduce the Mn species into zeolitic-imidazole frameworks (ZIFs) and then further pyrolyze the Mn-containing bimetallic ZIFs to synthesize core-shell-structured Co@Co 4 N nanoparticles embedded into MnO-modified porous N-doped carbon nanocubes (Co@Co 4 N/MnO NC). Co@Co 4 N/MnO NC exhibits the outstanding catalytic activity toward ORR and OER which is attributed to its abundant pyridinic/graphitic N and Co 4 N, the optimized content of MnO species, highly dispersed catalytic sites and porous carbon matrix. As a result, the Co@Co 4 N/MnO NC-based Zn–air battery exhibits enhanced performances, including the high discharge capacity (762 mAh g Zn −1 ), large power density (200.5 mW cm −2 ), stable potential profile over 72 h, low overpotential (<1.0 V) and superior cycling life (2800 cycles). Moreover, the belt-shaped Co@Co 4 N/MnO NC cathode-based Zn–air batteries are also designed which exhibit the superb electrochemical properties at different bending/twisting conditions.