Phase Engineering of Molybdenum Carbide-Cobalt Heterostructures for Long-Lasting Zn-Air Batteries

Developing highly active and robust oxygen catalysts is of great significance for the commercialization of Znair batteries (ZABs) with long-life stability. Herein, heterostructured catalysts comprising molybdenum carbide and metallic Co are prepared by a simple dicyandiamide-assisted pyrolysis strategy. Importantly, the crystalline phase of molybdenum carbide in the catalysts can be carefully regulated by adjusting the CoMoimidazole precursor and dicyandiamide ratio. The electronic configuration of Co and Mo centers as well as the phasedependent oxygen reduction reaction performance of these heterostructures (ss- Mo2C/Co, ss-Mo2C/.- MoC/Co, and.MoC/Co) was disclosed. A highly active.-MoC/Co cathode enables ZABs with outstanding long-term stability over 850 h with a low voltage decaying rate of 0.06 mV center dot h(-1) and high peak power density of 162 mW center dot cm(-2). This work provides a new idea for the rational design of efficient and stable cathode catalysts for ZABs.