Fe/IRMOF-3 derived porous carbons as non-precious metal electrocatalysts with high activity and stability towards oxygen reduction reaction

Abstract

By doping iron into isoreticular metal organic framework-3 (IRMOF-3) as a precursor and then annealing at 900°C under inert gas atmosphere, we have successfully prepared high efficient electrocatalyst of x%Fe/IRMOF-3-900 (x ranges from 1% to 10%) with porous carbon sphere structure. The electrocatalytic properties of the x%Fe/IRMOF-3-900 towards oxygen reduction reaction (ORR) are investigated by using rotating ring disk electrode (RRDE). The results demonstrate that the 1%Fe/IRMOF-3-900 exhibits the highest ORR activity: the onset and half-wave potentials are measured at 1.02V and 0.88V vs. RHE, respectively, together with electron transfer number of 3.90 at 0.4V, kinetic current density of 4.5mAcm−2 at 0.88V, and excellent longtime stability in alkaline solution. Such high ORR activity is is superior to many MOFs derived noble metal free electrocatalysts reported so far, and attributed to that the 1%Fe doped could retain the well-defined cubic morphology of the IRMOF-3, resulting in high surface area and large total pore volume, high nitrogen content and high density of electrocatalytic active N-species. This study provides a new strategy for preparation of non-precious metal ORR catalysts using the MOF as a precursor.