122nd General Meeting of the KCS

Type Symposium
Area Recent Trends in Catalysis Based on Nano-Porous Inorganic Materials
Room No. Room 323
Time FRI 15:55-:
Code INOR3-4
Subject Porphyrinic MOFs Driven Photocatalytic CO2 Reduction: Efficient Energy Migration from MOFs to Reduction Center
Authors Ho-Jin Son
Department of Advanced Materials Chemistry, Korea University, Sejong, Korea
Abstract A porphyrinic metal-organic framework (PMOF) known as PCN-222 was surface-modified by the molecular Re(I) catalyst through anchoring to the outer layer with carboxylate to form a new type of MOF hybrid photocatalyst. The porphyrinic MOF-based hybrid (PMOF|-Re) prepared with an archetypical CO2 reduction catalyst, (L)ReI(CO)3Cl (Re(I); L = 4,4′-dicarboxylic-2,2′-bipyridine), in the presence of 3 vol% water produced CO with no leveling-off tendency for 32 h to give a turnover number of ≥533 ± 57 (5,552 ± 593 μmol h–1 (g MOF)–1), which appears to be the highest reported for visible-light driven CO2 reduction systems based on combination of MOF and Re(I) molecular complex. The resultant high TON on the catalytic activity should mainly arise from efficient electron transfer from photoexcited porphyrin linkers (ZnPs*) to the periphery Re(I) catalytic sites, which is in line with the observed amplified quenching behavior (~ ps) of photo-excited electrons toward Re(I) catalytic centers in PMOF|-Re(I) hybrid (>7 μmol Re(I)/g PMOF). Such fast quenching might be expected to arise from energy (exciton) migration between porphyrin-like pigments (chlorophylls) and funneling into reduction site occurring in highly ordered porphyrin-based MOF|-Re(I) hybrid, which is reminiscent of natural photosystem I. A protective coating of TiO2 grown with post-treatment atomic layer deposition of TiO2 (TiO2-AIM) further improved the catalytic durability of this hybrid as a result of ALD-engendered structural strengthening of MOF, with its role as an electron mediator transferring the photo-excited electrons of PMOF toward the Re(I) reaction center.
E-mail hjson@korea.ac.kr