Sandwich-type Bimetal-Organic Frameworks/Graphene Oxide Derived Porous Nanosheets doped Fe/Co-N Active Sites for Oxygen Reduction Reaction

In this work, a bimetal-organic framework/graphene oxide with sandwich-type structure as a precursor is prepared by the solvent-thermal approach. A nanoporous reduced graphene oxide (rGO) nanosheets enriched with Fe, Co and N (Fe/Co-N) co-doped active sites is prepared followed by a high temperature carbonization and acid leaching (AL) process. When the molar ratio of Fe/Co is 0.40 before carbonization, the prepared sample exhibits optimized electrocatalytic activity (a high onset potential (0.98 V vs. RHE), half-wave potential (0.84 V vs. RHE), and a large limiting current density (-5.46 mA cm−2 at 0.21 V vs. RHE) as oxygen reduction reaction (ORR) electrocatalysts. Most importantly, the duration stability and methanol tolerance of the as-prepared sample are better than common commercial 20 wt% Pt/C under 0.10 M KOH alkaline condition. These results demonstrate the co-doping of bimetal Fe/Co and heteroatom N, excellent electrical conductivity of rGO and large surface area of nanoporous structure enhance the electrocatalytic activity. The successful synthesis of such nanoporous rGO nanosheets provides a facile way to explore a series of 2D non-precious metal electrocatalysts for energy conversion and storage devices.