122nd General Meeting of the KCS

Type Poster Presentation
Area Inorganic Chemistry
Room No. Grand Ballroom
Time 10월 19일 (금요일) 11:00~12:30
Code INOR.P-52
Subject Efficient Photochemical Carbon Dioxide Reduction of a Molecular Re(I) Catalyst-Immobilized Porphyrinic Metal-Organic Frameworks (PCN-222) Inspired by Photosensitizer Array of Photosystem I
Authors Sunghan Choi, So-Yoen Kim, Kyu Tai Park, Sang Ook Kang, Chul Hoon Kim*, Ho-Jin Son*
Department of Advanced Materials Chemistry, Korea University, 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), showed a high catalytic activity on CO2 reduction with a long-term stability. 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. In a typical run, the treated PMOF/TiO2|-ReI hybrid when assisted by 0.1 M sacrificial electron donor (SED) and 3 vol% weak Brønsted acid (namely, 2,2,-trifluoroethanol (TFE)) produced persistently CO with a >99% selectivity under the visible-light irradiation condition (>500 nm). The conversion efficiency of CO2 to CO reached up to >1,400 TON (turnover number) for a prolonged irradiation time (8 days), 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 fast exciton hopping transfer between adjacent porphyrin struts, which thus efficiently drives photo-electrons toward anchored Re(I) reduction center.
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