Trimetallic nanoarchitectonics of FeCoNi catalyst with modulated spin polarization for enhanced oxygen reduction performance

Fe-based catalysts have a good prospect in oxygen reduction reaction (ORR) in fuel cells. However, the catalytic activity of Fe-based catalysts requires further improvement to satisfy the demand in industrial application and the working mechanism is still shrouded in ambiguity. Here, a ferromagnetic catalyst with nitrogen-doped carbon supported FeCoNi alloy was synthesized by impregnation-pyrolysis method. The micromorphology and structure of the catalyst was analyzed by XRD, SEM, TEM, XPS, BET and Raman spectroscopy. The trimetallic catalyst showed high ORR activity in 0.1 M KOH with a half-wave potential of 0.908 V and a limiting current density of 6.153 mA cm−2, which was superior to 20 % Pt/C. The synergistic effect of FeCoNi alloy regulated the spin polarization and the regulated spin state improved ORR performance by facilitating the adsorption of O2 molecules and the conversion of the activated intermediates.