121st General Meeting of the KCS

Type Poster Presentation
Area Inorganic Chemistry
Room No. Event Hall
Time 4월 19일 (목요일) 11:00~12:30
Code INOR.P-143
Subject Highly Efficient Porphyrin-Driven CO2 Reduction via Hetero-Collisional Electron Transfer Route between Homogeneous Porphyrin and TiO2 Semiconductor
Authors Sunghan Choi, Hayeon Cheong, Chul Hoon Kim, Sang Ook Kang, Ho-Jin Son*
Department of Advanced Materials Chemistry, Korea University, Korea
Abstract A series of zinc porphyrin complex (ZnPD-dX(y): (ZnP = zinc phorphyrin), (D = 2,6-didodeclyoxyphenyl), (X = Triisopropylsylyl(Si); hydrogen(H)), and (y = triple bond(t); single bond(s)) was applied as visible-light photosensitizer in solution to the selective CO2 reduction to CO in the presence of an electron donor (BIH) and a hybrid catalyst (TiO2/ReC) prepared by anchoring of Re(4,4′-Y2-bpy)(CO)3Cl (Y = CH2PO(OH)2) on TiO2 particles. LED irradiation in N,N-dimethylformamide (DMF) at >500 nm resulted in the successful reduction of CO2 to CO with efficiencies in the order ZnPD-dH(s) > ZnPD-dSi(t) > ZnPD-dSi(t). The systems efficiently proceeded CO2 to CO conversion during photocatalysis. Under lower energy irradiation (>500 nm) with added 3 vol% water in DMF solvent, the ZnPD-dSi(t) hybrid showed a TONRe of ~900 over an extended time-period of 20 h. It was found via in-situ UV-Vis absorption spectroscopy that the added porphyrin photosensitizers experience a significant photomodification during photolysis: hydrogenation of the porphyrin to form chlorin and isobacteriochlorin units is observed. Detailed in-situ mass analysis of supernatant after photocatalysis revealed that the original structure of porphyrin derivatives was significantly modified or deformed with shortening the π-conjugation length and peeling off the bulky substituents on porphyrin derivatives. Overall, the photocatalytic activities of porphyrin-TiO2/Re(I) hybrid system differ greatly with varying the energy levels (reduction potentials) of porphyrin sensitizers and bulkiness of substituted ligand.
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