A Controllable Dual Interface Engineering Concept for Rational Design of Efficient Bifunctional Electrocatalyst for Zinc-Air Batteries

Searching for bifunctional noble-free electrocatalysts with high activity and stability are urgently demanded for the commercial application of zinc-air batteries (ZABs). Herein, the authors propose a controllable dual interface engineering concept to design a noble-metal-free bifunctional catalyst with two well-designed interfaces (Ni3FeN|MnO and MnO|CNTs) via a simple etching and wet chemical route. The heterointerface between MnO and Ni3FeN facilitates the charge transfer rate during surface reaction, and heterointerface between MnO and carbon nanotubes (CNTs) support provides effective electron transfer path, while the CNTs matrix builds free diffusion channels for gas and electrolyte. Benefiting from the advantages of dual interfaces, Ni3FeN/MnO-CNTs show superior oxygen reduction reaction and oxygen evolution reaction catalytic activity with an ultralow polarization gap ( increment E) of 0.73 V, as well as preferable durability and rapid reaction kinetics. As proof of concept, the practical ZAB with Ni3FeN/MnO-CNT exhibits high power density of 197 mW cm(-2) and rate performance up to 40 mA cm(-2), as well as superior cycling stability over 600 cycles, outperforming the benchmark mixture of Pt/C and RuO2. This work proposes a controllable dual interface engineering concept toward regulating the charge, electron, and gas transfer to achieve efficient bifunctional catalysts for ZABs.