Organometallic Iridium(III) Complex Sensitized Ternary Hybrid Photocatalyst for CO2 to CO Conversion

Pil Soo Kim; Sunghan Choi; So-Yoen Kim; Ju Hyoung Jo; Yoon Seo Lee; Bupmo Kim; Wooyul Kim; Wonyong Choi; Chul Hoon Kim; Ho-Jin Son; Chyongjin Pac; Sang Ook Kang

doi:10.1002/chem.201903136

Organometallic Iridium(III) Complex Sensitized Ternary Hybrid Photocatalyst for CO₂ to CO Conversion

Chemistry. 2019 Oct 22;25(59):13609-13623. doi: 10.1002/chem.201903136. Epub 2019 Sep 19.

Authors

Pil Soo Kim¹, Sunghan Choi¹, So-Yoen Kim¹, Ju Hyoung Jo¹, Yoon Seo Lee¹, Bupmo Kim^{2

3}, Wooyul Kim², Wonyong Choi³, Chul Hoon Kim¹, Ho-Jin Son¹, Chyongjin Pac¹, Sang Ook Kang¹

Affiliations

¹ Department of Advanced Materials Chemistry, Korea University, Sejong, 30019, South Korea.
² Department of Chemical and Biological Engineering, Sookmyung Women's University, Seoul, 04310, South Korea.
³ Division of Environmental Science and Engineering & Department of, Chemical Engineering, Pohang University of, Science Technology (POSTECH), Pohang, 37673, South Korea.

PMID: 31408218
DOI: 10.1002/chem.201903136

Abstract

A series of heteroleptic iridium(III) complexes functionalized with two phosphonic acid (-PO₃ H₂ ) groups (^dfppy IrP, ^ppy IrP, ^btp IrP, and ^piq IrP) were prepared and anchored onto rhenium(I) catalyst (ReP)-loaded TiO₂ particles (TiO₂ /ReP) to build up a new IrP-sensitized TiO₂ photocatalyst system (IrP/TiO₂ /ReP). The photosensitizing behavior of the IrP series was examined within the IrP/TiO₂ /ReP platform for the photocatalytic conversion of CO₂ into CO. The four IrP-based ternary hybrids showed increased conversion activity and durability than that of the corresponding homo- (IrP+ReP) and heterogeneous (IrP+TiO₂ /ReP) mixed systems. Among the four IrP/TiO₂ /ReP photocatalysts, the low-energy-light (>500 nm) activated ^piq IrP immobilized ternary system (^piq IrP/TiO₂ /ReP) exhibited the most durable conversion activity, giving a turnover number of ≥730 for 170 h. A similar kinetic feature observed through time-resolved photoluminescence measurements of both ^btp IrP/TiO₂ and TiO₂ -free ^btp IrP films suggests that the net electron flow in the ternary hybrid proceeds dominantly through a reductive quenching mechanism, unlike the oxidative quenching route of typical dye/TiO₂ -based photolysis.

Keywords: heterogeneous catalysis; iridium; photochemistry; sensitizers; supported catalysts.

Abstract

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