Confined Pt and M (M = Fe, Co) nanoparticles on NC with ultralow Pt loading for oxygen reduction reaction

Abstract

In this work, we have prepared Pt and M nanoparticles on nitrogen-doped carbon catalysts (Pt&M/NC, M = Fe, Co) with an ultralow Pt loading (<3 wt%) from room reduction of Pt and 3d transition metals by sodium borohydride on NC, where NC is firstly from pyrolysis of carbon black together with melamine. In Pt&M/NC (M = Fe, Co), Pt and 3d transition metals are in the individual nanoparticles with the size < 2 nm, where M is conducive to create the spatial confinement effect to anchor Pt nanoparticles. Meanwhile, Pt&M/NC (M = Fe, Co) has more internal defects than those of Pt/NC and M/NC. Owing to the synergistic effect of Pt and M together with NC, electrochemical results show that Pt&Co/NC has the ORR peak potential and half wave potential of 0.863 and 0.840 V vs. RHE, respectively, where they are 0.848 and 0.827 V vs. RHE for Pt&Fe/NC, more positive than that of Pt/NC. The average electron transfer number of Pt&M/NC (M = Fe, Co) is more than 3.8, close to the four-electron transfer way. This work provides a new method to reduce Pt use for ORR catalysts.