Crystalline/Amorphous Co₂P@FePO₄ Core/Shell Nanoheterostructures Supported on Porous Carbon Microspheres as Efficient Oxygen Reduction Electrocatalysts

Nanostructures with metallic crystalline cores and amorphous shells are recognized as promising catalysts for oxygen reduction (ORR) to enhance intrinsic activity and electroconductivity through strong interfacial interactions. Herein, a novel strategy involving crystallinity and nanostructure engineering is developed for constructing the amorphous ferric phosphate shell and the embedded crystalline Co2P core on three-dimensional interconnected carbon skeleton microspheres (Co2P@am-FePO4). Due to the excellent intrinsic activity and the enhanced electroconductivity from the strong electronic interactions between the amorphous ferric phosphate shell and crystalline Co2P core, the Co2P@am-FePO4 catalysts exhibit an excellent oxygen reduction electrocatalytic activity with a half wave potential as low as 0.91 V. More importantly, such excellent ORR performance can also translate to a high Zn–air performance as evidenced by a high specific energy density of 923 Wh/kgZn and maximum discharge power density of 152 mW/cm2.