Co formic-acid framework derived CoP/Co2P heterostructures confined in N, P-doped carbon as a bifunctional electrocatalyst for zinc-air batteries

Reasonable construction of efficient bifunctional catalysts for the oxygen reduction reaction (ORR) and the oxygen evolution reaction (OER) counts a great deal for the development and application of rechargeable zinc-air batteries. Herein, we prepared nano-sized heterostructural particles of cobalt phosphides (CoP/Co 2 P) confined in N, P-codoped cubic through simple grinding combined with vapor deposition method using the Co formic-acid framework (Co-FF) as the precursor. Benefit from the synergistic effect between the coexistence of abundant active sites including Co sites derived the CoP/Co 2 P nanoparticles, graphitic-N, pyridinic-N species and regulation of heterojunction interface electrons, the CoP/Co 2 P@NPC-800 catalyst exhibited excellent bifunctional catalytic activity toward ORR and OER, slightly better than commercial 20 % Pt/C. The liquid zinc-air battery demonstrates a specific capacity of 720.1 mAh g −1 and outstanding stability exceeds 250 h, comparable to 20 % Pt/C. Moreover, the flexible zinc-air battery can maintain good stability under different angles of bending. This study has a certain theoretical guiding significance for the rational regulation of the phase of cobalt-based phosphide to fabricate bifunctional oxygen catalysts for metal-air battery applications.