Hierarchically porous CoMn-N-doped carbon nanotubes as efficient electrocatalyst for oxygen reduction reaction

Considering the advantages of polypyrrole (PPy) tubes and Co/Mn-doped zeolitic imidazolate framework-8 (ZIF-8), CoMn nanoparticles are uniformly anchored onto N-doped carbon nanotube (NCNT) through pyrolyzing the CoMn-ZIF-8@PPy precursor, isolating the CoMn@NCNT catalyst. The hierarchical pore structure and high electron conductivity of NCNT collaboratively boost the mass/electron transport as well as reaction kinetics during the catalysis, meanwhile the as-generated Co/Mn-N_x species significantly facilitate the improvement of catalytic activity. The CoMn@NCNT catalyst shows a half-wave potential of 0.82 V and superb durability towards the ORR. In addition, the flow and flexible zinc-air batteries assembled with CoMn@NCNT display superb charge/discharge cycling performances. This study affords a feasible strategy for constructing metal,N-codoped carbon-based bifunctional electrocatalysts with tubular structure for rechargeable zinc-air batteries.