Template-free synthesis of non-noble metal single-atom electrocatalyst with N-doped holey carbon matrix for highly efficient oxygen reduction reaction in zinc-air batteries

Abstract M-N-C single-atom electrocatalysts recently have received significant attention because of high catalytic activity and maximal atom utilization. Here, it is firstly reported that macrocycle cucurbit[6]uril (CB[6]) self-assembly was employed as precursor to fabricate M-N-C single-atom electrocatalysts for the Zn-air battery (ZAB). This template-free method using CB[6] self-assembly acquires the holey N-doped matrixes with hierarchical micro/mesoporous structure. The Fe loaded N-doped holey carbon single-atom electrocatalyst (Fe-NHC) exhibited high activity with the half-wave potential (E1/2) of 0.89 V versus reversible hydrogen electrode (RHE) for oxygen reduction reaction (ORR) in alkaline condition, which was better than those of Co or Ni loaded catalyst and commercial Pt/C (E1/2 = 0.83 V). Moreover, the ZAB employing Fe-NHC catalyst achieved higher power and energy density with longer-term stability than those of Pt/C + Ir/C catalyst. This work provided a promising strategy to design stable and highly efficient catalyst for long-life electrochemical storage devices.