Mechanistic study of photocatalytic CO2reduction using a Ru(ii)-Re(i) supramolecular photocatalyst

Kei Kamogawa, Yuushi Shimoda, Kiyoshi Miyata, Ken Onda, Yasuomi Yamazaki, Yusuke Tamaki, Osamu Ishitani

Research output: Contribution to journalArticlepeer-review

3 Citations (Scopus)

Abstract

Supramolecular photocatalysts comprising [Ru(diimine)3]2+photosensitiser andfac-[Re(diimine)(CO)3{OC(O)OC2H4NR2}] catalyst units can be used to reduce CO2to CO with high selectivity, durability and efficiency. In the presence of triethanolamine, the Re catalyst unit efficiently takes up CO2to form a carbonate ester complex, and then direct photocatalytic reduction of a low concentration of CO2,e.g., 10% CO2, can be achieved using this type of supramolecular photocatalyst. In this work, the mechanism of the photocatalytic reduction of CO2was investigated applying such a supramolecular photocatalyst,RuC2Rewith a carbonate ester ligand, using time-resolved visible and infrared spectroscopies and electrochemical methods. Using time-resolved spectroscopic measurements, the kinetics of the photochemical formation processes of the one-electron-reduced speciesRuC2(Re), which is an essential intermediate in the photocatalytic reaction, were clarified in detail and its electronic structure was elucidated. These studies also showed thatRuC2(Re)is stable for 10 ms in the reaction solution. Cyclic voltammograms measured at various scan rates besides temperature and kinetic analyses ofRuC2(Re)produced by steady-state irradiation indicated that the subsequent reaction ofRuC2(Re)proceeds with an observed first-order rate constant of approximately 1.8 s−1at 298 K and is a unimolecular reaction, independent of the concentrations of both CO2andRuC2(Re)

Original languageEnglish
Pages (from-to)9682-9693
Number of pages12
JournalChemical Science
Volume12
Issue number28
DOIs
Publication statusPublished - Jul 28 2021

All Science Journal Classification (ASJC) codes

  • Chemistry(all)

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