Facile synthesis of nitrogen- and phosphorus-Co-doped porous carbon nanosheets embedded with FeP clusters for the oxygen reduction reaction using rechargeable zinc-air batteries

There is an urgent need to develop non-precious-metal electrocatalysts for the oxygen reduction reaction (ORR) to replace traditional noble-metal electrocatalysts in zinc-air batteries (ZAB). Herein, we describe the preparation of N-, P-co-doped iron-based porous carbon nanosheets formed by doping iron into N-, P-co-doped nanosheets. Due to its unique core–shell structure and the synergistic effect between active sites, the electrocatalyst (FP0.6@CNP1000) exhibits high ORR activity in alkaline solution, with a remarkable half-wave potential (0.852 V vs RHE), high current density (5.41 mA cm−2), good stability, and excellent methanol tolerance. The FP0.6@CNP1000 electrocatalyst can be used as the cathode in a ZAB, thereby catalyzing the ORR, which achieves an open-circuit potential of 1.455 V, peak power density of 80 mW cm−2, and excellent cycling stability for over 58 h. Density functional theory (DFT) calculations reveal that the ORR active site consists of an Fe center linked to three adjacent P atoms, and that the strong interactions between the substrate and the FeP cluster contribute to the ORR capacity.