MOF-Derived Porous Fe-N-C Materials for Efficiently Electrocatalyzing the Oxygen Reduction Reaction
Yifan Wang, Liming Chen, Yongjian Lai, Yi Wang, Kun Wang, Shuqin Song
Abstract
Fe-based metal–organic framework (MOF)-derived Fe-N-C materials as non-precious-metal oxygen reduction reaction (ORR) electrocatalysts to replace commercial Pt/C and realize real commercial applications still suffer from poor intrinsic electrical conductivity and part embedding or agglomeration of Fe-N active sites. Herein, we develop conductivity-enhanced MOF-derived porous Fe-N-C material via pyrolyzing Fe-based MOF particles (Fe-MIL-NH2) in situ grown onto as-prepared three-dimensional (3D) nitrogen-doped porous carbon materials (NPCs). Benefiting from the enhanced electrical conductivity, good dispersibility of Fe-N active sites, and rapid mass transfer due to the 3D ordered interconnected NPC framework, the best-performing sample (Fe3O4/NPC-50-900) exhibits an onset potential of 0.96 V (vs reversible hydrogen electrode (RHE)) and a limiting current density of 5.2 mA/cm2 for electrocatalyzing ORR in 0.1 M KOH aqueous solution, which is comparable to that of commercial Pt/C (20 wt %, Johnson Mattey Corp.). Moreover, Fe3O4/NPC-50-900 also exhibits good methanol tolerance and long-term durability. This work provides a feasible strategy to address the issues of poor electrical conductivity and inferior Fe-N active site exposure of Fe-N-C materials derived from Fe-based MOFs, thus accelerating the practical application of MOF-derived materials.