Bimetallic Co_3.2Fe_0.8N–Nitrogen–Carbon Nanocomposites for Simultaneous Electrocatalytic Oxygen Reduction, Oxygen Evolution, and Hydrogen Evolution

To develop an efficient and inexpensive electrocatalyst with the ability to catalyze ORR/OER/HER synchronously, a Co–Fe bimetallic nitride combined with a transitional metal-N-doped carbon nanocomposite has been crafted via the sodium borohydride reduction and following nitride treatment. Electrochemical characterization has signified that the resulting Co–Fe bimetallic nitride with a Co/Fe molar ratio of 4:1 is highly active for electrocatalysis of OER with the lowest overpotential at 10 mA cm–2 (419 mV) among all the tested Co–Fe nitrides, even lower than that of the IrO2 benchmark, and also active on HER. Further, a ZIF-derived carbon has been added to form a Co3.2Fe0.8N/MNC nanocomposite with better trifunctional activity for OER/ORR/HER than that of the single Co3.2Fe0.8N nanoparticle. The unique nanocomposite structure, which is flower-like nanosheets attached on the surface of depressed walnut-like spheres, electronic interaction between the Fe and Co atoms, and rich M–N or N–C active sites created by MNC joining into Co3.2Fe0.8N would explain the outstanding trifunctional catalytic activity. Moreover, the obtained Co3.2Fe0.8N/MNC nanomaterial has superior long-term stability for ORR, HER, and OER. Therefore, as a strong competitor to Ir- or Pt-based electrocatalysts, this bimetallic Co–Fe nitride/MNC nanocomposite has been expected to be incorporated into clean and efficient energy devices.