MOF-derived CoN/CoFe/NC bifunctional electrocatalysts for zinc-air batteries

Zinc air battery (ZAB) is one of promising devices to solve the problems of fossil energy consumption and environmental pollution, but the development of low-cost non-precious metal dual-functional catalysts for ZAB still remains a great challenge. Here, we synthesize a bifunctional catalyst (Co5.47N/Co3Fe7/NC) consisting of two kinds of active sites. The Co5.47N/Co3Fe7/NC catalyst shows excellent electrocatalytic activities with a half-wave potential of 0.89 V (versus RHE) for ORR and a low potential of 1.609 V at 10 mA cm−2 for OER in alkaline condition. When the catalyst was used in ZAB, the ZAB provides a maximal power density of 264 mW cm−2 and maintains a stable voltage gap over 180 h. The results show that Co5.47N plays a very important role in both ORR and OER processes, because it effectively improves the conductivity of catalysts. Moreover, the two-phase interface produced by the two crystal structures will produce an electronic coupling effect, forming a large number of active sites. This catalyst provides a reliable alternative to air cathode catalysts for rechargeable zinc air batteries.