Constructing Precise Coordination of Nickel Active Sites on Hierarchical Porous Carbon Framework for Superior Oxygen Reduction.

Abstract

Single-atom catalysts (SACs) with specific coordination environment are expected to be efficient electrocatalysts for oxygen reduction reaction (ORR). Herein, Ni\uf8ffN4 \uf8ffC10 coordination site is constructed through encapsulating Ni2+ into the cavity of ZIF-8 as a self-sacrificing precursor and anchoring it on 3D N-doped carbon frameworks. The Ni\uf8ffN4 \uf8ffC10 catalyst shows excellent ORR activity and stability, with a high half-wave potential (0.938\xa0V vs RHE), which is currently the best performances in Ni-based SACs. The remarkable performance with high ORR activity in alkaline solution is attributed to the single-atom nickel active sites with faster electron transport and suitable electronic structure. Moreover, the power density of zinc-air battery assembled by Ni\uf8ffN4 \uf8ffC10 as cathode is 47.1% higher than that of the commercial Pt/C. This work not only provides a facile method to prepare extremely active Ni-based SACs, but also studies the intrinsic mechanism toward the oxygen reduction reaction under alkaline condition.