N, F dual-doped carbon embedded with Co&CoN paragenetic structure for oxygen electrocatalytic reduction reaction

Developing effective earth aboundant non-precious metal electrocatalysts for oxygen reduction reaction (ORR) is highly demanded in clean energy conversion systems, such as fuel cells. In this work, we demonstrate N,F dual-doped carbon embedded with Co&CoN paragenetic structure (N,F–Co&CoN@C) as an effective ORR electrocatalyst through directly pyrolyzing the solid mixture of cobalt chloride hexahydrate, melamine hydrogen fluoride and carbon black in an N2 atmosphere. N,F–Co&CoN@C prepared at 700 °C (N,F–Co&CoN@C700) exhibits an excellent electrocatalytic performance with the ORR peak potential (Ep) at 0.875 V, the half wave potential (E1/2) at 0.871 V and a nearly four-electron reaction path in 0.1 M KOH. It also displays a better stability and methanol-tolerance than that of the commercial 40 wt% Pt/C. Origin of this outstanding performance of the prepared N,F–Co&CoN@C700 comes from the synergistic effect of Co&CoN and N,F–C in the hybrid materials. TEM images, STEM-mapping images, XRD and XPS results verify that N,F–Co&CoN@C700 has a core@shell structure with Co&CoN paragenetic structure embedded in N, F dual-doped carbon. Its specific surface area is calculated to be 1018 m2/g with a high defect degree of the ID/IG at 1.31.