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-n oble-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-3[Co(CN)(6)](2 )and NaH2PO2 precursors were carbonized into N,P-doped carbon nanospheres with the active species of both bimetallic CoFe phosphides and CoCx nanoparticles (denoted as CoCx/(Co0.55Fe1.945)(2)P@C). By employing the CoCx/(Co0.55Fe1.945)(2)P@C as oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) electrode catalysts, superior catalytic activity is achieved with E-1/2 of 0.84 V for ORR, and overpotential of 0.39 Vat 10 mA cm (2) for OER in an alkaline medium, respectively. Furthermore, CoCx/(Co0.55Fe1.945)(2)P@C as air electrode for rechargeable Zn-air battery shows power density as high as 131 mW cm (2) and charge-discharge cycle stability, and this suggests the potential application of CoCx/(Co0.55Fe1.945)(2)P@C in energy transformation systems. The high electrocatalytic performances are revealed to originate from the change of electronic structure of bimetallic (Co0.55Fe1.945)(2)P via introducing P into the Co0.55Fe1.945 alloy, resulting in a decreased energy gap of CoCx/(Co0.55Fe1.945)(2)P@C relative to that of CoCx/Co0.55Fe@C. This work proposes a versatile strategy to develop multifunctional non-precious catalysts for this kind of energy-related electrocatalytic reactions. (C) 2021 Elsevier Inc. All rights reserved.