In situ growth of CoP nanoparticles anchored on (N,P) co-doped porous carbon engineered by MOFs as advanced bifunctional oxygen catalyst for rechargeable Zn-air battery

Screening and constructing low cost, highly efficient and robust electrocatalysts with high oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) activity is crucial for rechargeable metal-air batteries. Metal phosphides coupled with heteroatom doped carbon are promising candidates for oxygen electrodes. In this work, we demonstrate a facile strategy to synthesize cobalt phosphide anchored heteroatom (N,P) co-doped porous carbon (CoP/NP-HPC) through a one-step pyrolysis of bimetal-organic frameworks with a simplein situphosphorization process. In alkaline solution, the obtained CoP/NP-HPC catalyst exhibits high bifunctional catalytic activity toward ORR and OER, comparable to commercial 20% Pt/C or even better, which is attributed to the synergistic effect between the CoP active sites and N,P co-doped carbon, and the porous framework as a channel benefiting the diffusion of reaction species. Notably, a rechargeable Zn-air battery with CoP/NP-HPC as the cathode electrocatalyst delivers a high power density of 186 mW cm⁻², as well as good long-term charge/discharge cyclic stability, outperforming 20% Pt/C. The hybrid catalyst of CoP anchored heteroatom doped carbon provides a possibility and an opportunity to promote the development of low-cost and highly efficient bifunctional catalysts for ORR and OER in applications of metal-air batteries.