Interface Electronic Modulation of Monodispersed Co Metal-Co7Fe3 Alloy Heterostructures for Rechargeable Zn–Air Battery

Engineering heterointerfaces between metal and alloy to facilitate charge transfer would be an attractive strategy for superefficient electrocatalysis. Herein, a simple xerogel-pyrolysis strategy has been designed to prepare an advanced bifunctional electrocatalyst, Co/Co7Fe3 confined by a porous N-doped carbon nanosheets/CNTs composite (Co/Co7Fe3@PNCC). The formative Co/Co7Fe3 heterostructure promoted the charge transfers from metal Co to active alloy Co7Fe3, thus reducing the energy barrier of the oxygen reduction reaction and improving the catalytic kinetics and active surface area for the oxygen evolution reaction. The PNCC provided monodispersed confined space for Co/Co7Fe3 particles, which also owned a high specific surface area for ions/gases diffusion. Therefore, Co/Co7Fe3@PNCC exhibited excellent bifunctional oxygen catalysis activities and durability with an ultralow polarization gap (ΔE) of only 0.64 V. When practically adopted as an air electrode in ZAB, a large open-circuit voltage of 1.534 V, a maximum power density of 211.82 mW cm–2, an ultrahigh specific capacity of 807.33 mAh g–1, and superior durability over 800 h were obtained. This catalyst design concept offers a facile strategy toward modulating electronic structure to achieve efficient bifunctional electrocatalysts for ZAB.