In situ induced growth strategy of Co2P nanocrystals encapsulated into stable 3D carbon network as a bifunctional electrocatalyst for Zn-air battery

Rational design of inexpensive and robust carbon-based bifunctional catalysts is of considerable interest for practical application of rechargeable Zn-air battery (ZAB) tech-nology. Herein, a facile in-situ induced growth strategy is developed to construct Co2P nanocrystals encapsulated into a stable 3D carbon nanotube-modified graphene network (Co2P@NPCNG). Specifically, cobalt tetranitrophthalocyanine (CoPc(NO2)4) is employed not only as the coupling agent to form and complex Co2P nanocrystals with graphene, but also as the inducer to catalyze the graphitization of melamine to grow the uniform Co2P nanocrystal-encapsulated CNTs on graphene in situ. Encouragingly, the as-synthesized Co2P@NPCNG exhibits favorable bifunctional oxygen electrocatalytic activity, fast reac-tion kinetics and excellent stability. Impressively, both liquid ZAB and all-solid-state ZABs used Co2P@NPCNG as air-cathode catalysts display considerable open-circuit voltage,