Homogenized Bimetallic Catalysts from Metal–Organic Framework Alloys

Abstract

Metal–organic frameworks (MOFs) are an important class of materials for the preparation of oxygen reduction reaction (ORR) catalysts but are limited in that only a single metal ion is used. By alloying MOFs of various metal ions, catalytic properties of a material could be enhanced compared to its individual components. However, traditional solution-based synthesis using two different metal ions results in heterogeneous domains of both species. We found that mechanically alloying [Fe(1,2,3-triazolate)2] with isostructural [Cu(1,2,3-triazolate)2] results in tunable, homogeneously dispersed, bimetallic MOF alloys, which when pyrolyzed, retain bimetallic homogeneity and can be used as ORR catalysts. The bimetallic catalysts synergize and show exceptional ORR performance, outperforming the benchmark Pt/C, attributed to the homogenous distribution and control of the Fe2+ and Cu2+ composition within the MOF crystals, which cannot be obtained by solution-based synthesis. The findings show that MOFs described in literature could be alloyed together and show synergistic properties that outperform the individual components.