Fabrication of core-shell nanohybrid derived from iron-based metal-organic framework grappled on nitrogen-doped graphene for oxygen reduction reaction

It is of significance to replace Pt-based electrocatalyst with high activity and low price non-noble metal oxygen reduction reaction (ORR) electrocatalysts for large-scale application of fuel cells. Herein, we display a kind of core-shell hybrid composed of Fe/Fe3C@nitrogen-doped carbon decorated on graphene (denoted as Fe/Fe3C@ NC-Gs) as the efficient ORR electrocatalyst. The optimal-performing Fe/Fe3C@NC-G-2 catalyst presents an outstanding ORR performance in terms of a high onset potential (E-onset) of 0.97 V (vs. RHE) and half-wave potential (E-1/2) of 0.88 V (vs. RHE), respectively, possible to rival those of the commercially available Pt/C in an alkaline electrolyte solution. Besides, the Fe/Fe3C@NC-G-2 catalyst manifests better stability and methanol tolerance than those of commercially available Pt/C, which is of importance for the excogitation and fabrication of novel electrocatalysts originated from non-precious metals. Accordingly, it is confirmed that the integration of Fe/Fe3C@NC and graphene enables plentiful active sites stemmed from different active species of Fe3C, Fe, and NC and intrinsic hierarchically porous structure with intimate contact of various components, which would give Fe/Fe3C@NC-G-2 a positive impact on ORR activity.