Reinforcing oxygen electrocatalytic activity via selective dual-phase heterointerface engineering for rechargeable Zn–air batteries

Dual-phase heterointerface electrocatalysts (DPHE) constructed by oxygen reduction reaction (ORR)- and oxygen evolution reaction (OER)-active elements exhibit excellent bifunctional activity and long-term durability due to the abundant interface exposure and synergistic catalytic effect. Herein, low-dimensional N-doped graphene nanoribbons (N-GNRs) coupling with ultrathin CoO nanocomposites (N-GNRs/CoO) were controllably fabricated through a facile two-step approach using synthesized Co(OH) 2 nanosheet as CoO precursor. Density functional theory (DFT) calculations and experimental characterizations prove that the formation of interface between N-GNRs and CoO can induce local charge redistribution, contributing to the improvement of catalytic activity and stability. The optimal N-GNRs/CoO DPHE possesses hierarchically porous architectures and presents outstanding bifunctional activities with a small potential gap of 0.729 V between the potential at 10 mA·cm −2 for OER and the halfwave potential for ORR, which outperforms Pt/C + IrO 2 and the majority of noble-metal-free bifunctional catalysts. Liquid- and solid-state rechargeable Zn–air batteries assembled with N-GNRs/CoO as the cathode also display high peak power density and fantastic cycle stability, superior to that of benchmark Pt/C + IrO 2 catalyst. It is anticipated to offer significant benefits toward high activity, stability and mechanical flexibility bifunctional oxygen electrocatalysts for rechargeable Zn–air batteries. Graphical abstract