The cobalt carbide/bimetallic CoFe phosphide dispersed on carbon nanospheres as advanced bifunctional electrocatalysts for the ORR, OER, and rechargeable Zn-air batteries.

It is very important, but also challenging to produce high-activity, high durability and affordable non-noble-metal-bifunctional-electrocatalysts for sustainable energy application. Here, one-pot synthesized iron covalent porphyrin polymers (FePor-CPP), with carefully placed Fe, N atoms, a regular porous structure, Co[Co(CN)] and NaHPO precursors were carbonized into N,P-doped carbon nanospheres with the active species of both bimetallic CoFe phosphides and CoC nanoparticles (denoted as CoC/(CoFe)P@C). By employing the CoC/(CoFe)P@C as oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) electrode catalysts, superior catalytic activity is achieved with E of 0.84 V for ORR, and overpotential of 0.39 V at 10 mA cm for OER in an alkaline medium, respectively. Furthermore, CoC/(CoFe)P@C as air electrode for rechargeable Zn-air battery shows power density as high as 131 mW cm and charge-discharge cycle stability, and this suggests the potential application of CoC/(CoFe)P@C in energy transformation systems. The high electrocatalytic performances are revealed to originate from the change of electronic structure of bimetallic (CoFe)P via introducing P into the CoFe alloy, resulting in a decreased energy gap of CoC/(CoFe)P@C relative to that of CoC/CoFe@C. This work proposes a versatile strategy to develop multifunctional non-precious catalysts for this kind of energy-related electrocatalytic reactions.