Ultra-high voltage efficiency rechargeable zinc-air battery based on high-performance structurally regulated metal-rich nickel phosphides and carbon hybrids bifunctional electrocatalysts

Metal phosphides featuring electronic structure similar to Pt-group metal have triggered substantial concerns, and unveiling active species is crucial to rational design of bifunctional catalysts for ORR and OER. Herein, a hybrid of metal-rich nickel phosphides strongly coupled with heteroatom-doped carbon (NixP-NP-C) is constructed by a facile pyrolysis combined with in-situ phosphorization of MOFs. This unique hybrid exhibits superior electrocatalytic activity and stability toward ORR and OER demonstrated by delightful high Eonset and E1/2 up to 0.90 and 0.76 V, respectively, along with a long-term stability. The resulting zinc-air battery shows an impressively small charge-discharge voltage gap and delivers a high power density of 266 mW cm−2. The high catalytic performance of NixP-NP-C can be ascribed to synergistic effect of metal-rich Ni2P actives and heteroatoms doped porous carbon. Consequently, hybrid of carbon and metal phosphides may provide a meaningful reference for developing high performance oxygen catalysts in metal-air battery.