Iron and nitrogen co-functionalized porous 3D graphene frameworks as an efficient oxygen reduction catalyst

Abstract

Porous 3D graphene decorated by Fe species and N-doping (Fe/N-GAs) has been prepared by a cost-effective strategy. Benefiting from the characteristics of coordinating with metals and possessing a high nitrogen content, poly-2,6-diaminopyridine (PDAP) is preferably selected as nitrogen doping source. It is found that the active site species and defects on Fe/N-GAs samples are influenced by both pyrolyzing temperature and content of Fe, moreover, the Fe content can affect the morphology and structure of Fe/N-GAs, so the electrocatalytic activity towards the ORR on Fe/N-GAs can be tuned. The Fe/N-GAs with highly effective activity sites, connected pores and high surface area exhibit comparable activity (E_onset = −0.04 V vs. SCE, E_1/2 = −0.21 V vs. SCE, J_L = 6.65 mA cm⁻²) to commercial Pt/C, better stability and better tolerance to methanol than Pt/C in alkaline medium as well as improved activity compared to N-GAs in acidic medium.