Interfacial nanoparticles of Co2P/Co3Fe7 encapsulated in N-doped carbon nanotubes as bifunctional oxygen electrocatalysts for rechargeable zinc-air batteries

Heterostructures have been generally proven beneficial to the electrocatalysis performance due to tailorable electronic structures. Herein, we develop a facile one-step strategy to synthesize Co2P/Co3Fe7 heterointerfacial nanoparticles encapsulated within N-doped carbon nanotubes (Co2P/Co3Fe7@N-C). The electrocatalyst exhibits a bifunctional oxygen evolution/reduction reaction (OER/ORR) activity (ΔE = 0.669 V) that far exceeds that of commercial Pt/C + Ir/C catalysts (ΔE = 0.76 V). In this study, Co2P/Co3Fe7@N-C-based zinc air batteries (ZABs) exhibit a higher power density (151.6 mW cm-2) and longer stability (1600 cycles) than commercial Pt/C + Ir/C-based ZABs (80 mW cm-2, 450 cycles). Density functional theory calculations reveal that the interfacial electronic interaction between Co2P and Co3Fe7 play key roles in boosting bifunctional ORR/OER efficiency. This work may open a new pathway for rational design of superior bifunctional oxygen electrocatalysts for rechargeable metal-air batteries through interfacial engineering.