Pt-Fe alloy supported on Fe/NC catalyst with high activity and durability for oxygen reduction reaction

Abstract

In this paper, Pt-Fe alloy with low-content of Pt (2 %) was distributed uniformly over the porous Fe/NC substrate treated by nitric acid etching, with small amount of metallic Fe and Pt nanoparticles. The optimized Pt-Fe alloy on Fe/NC substrate showed higher ORR performance with the E1/2 of around 0.83 V vs. RHE as well as faster catalytic kinetics. In addition, the catalytic activity has not been decayed through an accelerated durability test after 5000 cycles CVs, indicating better catalytic stability for the alloying catalyst. The introduction of Pt elements into Fe/NC substrate increased the numbers and species of ORR active sites, invoking higher ORR activity comparing with isolated Fe/NC catalyst. The acid etching provided more defects for the substrate to anchor the active sites stably. Moreover, the synergistic effect originated from the alloying of Pt and Fe modulated the electronic structure of Pt, increasing the ORR activity with low yield of H2O2. This decreasing H2O2 yield can weaken the Fenton reaction to prevent the dissolution of Fe in the acid solution, which can improve the stability of the catalysts to meet the commercial needs for PEMFC.