Hybrid bimetallic-N4 electrocatalyst derived from a pyrolyzed ferrocene–Co-corrole complex for oxygen reduction reaction

Abstract

A bimetallic macrocyclic-N4 complex, FCC, consisting of a Co-corrole core equipped with a peripheral ferrocene has been synthesized. The complex structure was thoroughly characterized using single crystal X-ray diffraction. The Co-corrole, mono-substituted with a peripheral Fe-complex, exhibited unique characteristics after its pyrolysis for oxygen reduction reaction (ORR) activity. Carbon black supported FCC, pyrolyzed at 500 °C, gives an electrocatalyst with a bimetallic (Co and Fe) active center, which facilitates ORR via a 4-electron pathway. The new non-precious bimetallic electrocatalyst exhibits a high electron transfer number of more than 3.95, with a H₂O₂ yield of below 2.3%, over the potential range of 0.2–0.8 V for ORR in acidic medium, which is superior to pyrolyzed Co-corroles. The enhanced ORR activity for the catalyst derived from this technique provides a new prospect for next-generation non-precious N4 electrocatalysts for fuel cell applications.