Fe-Porphyrin-Based Metal–Organic Framework Films as High-Surface Concentration, Heterogeneous Catalysts for Electrochemical Reduction of CO₂

Abstract

Realization of heterogeneous electrochemical CO 2 -to-fuel conversion via molecular catalysis under high-flux conditions requires the assembly of large quantities of reactantaccessible catalysts on conductive surfaces. As a proof of principle, we demonstrate that electrophoretic deposition of thin films of an appropriately chosen metal−organic framework (MOF) material is an effective method for immobilizing the needed quantity of catalyst. For electrocatalytic CO 2 reduction, we used a material that contains functionalized Fe-porphyrins as catalytically competent, redox-conductive linkers. The approach yields a high effective surface coverage of electrochemically addressable catalytic sites (∼10 15 sites/cm 2 ). The chemical products of the reduction, obtained with ∼100% Faradaic efficiency, are mixtures of CO and H 2 . These results validate the strategy of using MOF chemistry to obtain porous, electrode-immobilized, networks of molecular catalysts having competency for energyrelevant electrochemical reactions.

Electrocatalytic Metal–Organic Frameworks for Energy Applications

“…[133] Catalyst degradation was also observed in the presence of 1 m TFEa st he current density drops off during the 5h CPE. Postcatalysis characterization studies of Fe_MOF-525 to confirm that catalyst degradation was the cause of the reduction in current density were not reported.…”

“…[133] Thin-film MOF-525c an be postmetalatedw ithi ron to result in 93 %i ncorporation (Fe_MOF-525). The iron porphyrin linkers serve as the electrocatalysts and facilitate charget ransfer through redoxh opping betweent he catalytic sites.…”

Facile Synthesis of M-MOF-74 (M=Co, Ni, Zn) and its Application as an ElectroCatalyst for Electrochemical CO2 Conversion and H2 Production

“…Recently, there have been attempts to apply metal organic frameworks (MOFs) as catalysts for the electrochemical conversion of CO 2 [25][26][27][28] and H 2 production [29,30]. MOFs are made of metal ions coordinated to organic ligands, giving rise to characteristic three-dimensionally ordered crystalline structures.…”

Assembly of Covalently Inorganic-Organic Hybrid Molecular Framework Based on Porphyrin and Phthalocyanine Derivatives—Sensitizer for Dye Sensitized Solar Cells

“…Film of tetra(4-carboxyphenyl)porphyrin Fe complex-Zr-O cluster possessed high face concentration, and as catalysts for electroreduction from CO 2 to CO, the overpotential was efficiently reduced [25]. The similar film of carboxyphenyl porphyrin Co complex-Al-O cluster supplied the same catalytic behavior [26].…”

“…Recently, a specialized commentary about heterogeneous catalysis was reviewed [36]. Assembly types of MOFs based on porphyrin/phthalocyanine were summarized as: 1) porphyrin molecules (peripheral groups were usually selected as carboxyl) were combined with hard acid-O clusters, and the hard acids were high valence ions, including Al and Zr [25] [26] [27] [28]; 2) porphyrin molecules were linked with complexes (i.e., Ni-pyridine complexes) [29]; 3) peripheral-central axial coordination and bridge axial coordination constructed crystal porphyrin MOFs; and 4) covalent bond bridged porphyrins mainly depended on covalently conjugate pair of Schiff base bonds, which were constructed by the condensation between aminophenyl porphyrins with p-phthalaldehyde and with biphenyl-4, 4'-dicarboxaldehyde. These MOFs were also known as COFs (Covalent Organic Frameworks) [11] [30]- [38].…”