title: Nature-Inspired, Highly Durable CO2 Reduction System Consisting of a Binuclear Ruthenium(II) Complex and an Organic Semiconductor Using Visible Light.
abstract: A metal-free organic semiconductor of mesoporous graphitic carbon nitride (C3N4) coupled with a Ru(II) binuclear complex (RuRu') containing photosensitizer and catalytic units selectively reduced CO2 into HCOOH under visible light (λ > 400 nm) in the presence of a suitable electron donor with high durability, even in aqueous solution. Modification of C3N4 with Ag nanoparticles resulted in a RuRu'/Ag/C3N4 photocatalyst that exhibited a very high turnover number (>33000 with respect to the amount of RuRu'), while maintaining high selectivity for HCOOH production (87-99%). This turnover number was 30 times greater than that reported previously using C3N4 modified with a mononuclear Ru(II) complex, and by far the highest among the metal-complex/semiconductor hybrid systems reported to date. The results of photocatalytic reactions, emission decay measurements, and time-resolved infrared spectroscopy indicated that Ag nanoparticles on C3N4 collected electrons having lifetimes of several milliseconds from the conduction band of C3N4, which were transferred to the excited state of RuRu', thereby promoting photocatalytic CO2 reduction driven by two-step photoexcitation of C3N4 and RuRu'. This study also revealed that the RuRu'/Ag/C3N4 hybrid photocatalyst worked efficiently in water containing a proper electron donor, despite the intrinsic hydrophobic nature of C3N4 and low solubility of CO2 in an aqueous environment.
authors.affiliation: Department of Chemistry, School of Science, Tokyo Institute of Technology , 2-12-1-NE-2 Ookayama, Meguro-ku, Tokyo 152-8550, Japan.
authors.forename: Ryo
authors.initials: R
authors.lastname: Kuriki
authors.affiliation: Graduate School of Engineering, Toyota Technological Institute , 2-12-1 Hisakata, Tempaku, Nagoya 468-8511, Japan.
authors.forename: Hironori
authors.initials: H
authors.lastname: Matsunaga
authors.affiliation: Department of Chemistry, School of Science, Tokyo Institute of Technology , 2-12-1-NE-2 Ookayama, Meguro-ku, Tokyo 152-8550, Japan.
authors.forename: Takuya
authors.initials: T
authors.lastname: Nakashima
authors.affiliation: Department of Chemistry, School of Science, Tokyo Institute of Technology , 2-12-1-NE-2 Ookayama, Meguro-ku, Tokyo 152-8550, Japan.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Wada
authors.affiliation: Graduate School of Engineering, Toyota Technological Institute , 2-12-1 Hisakata, Tempaku, Nagoya 468-8511, Japan.|PRESTO, Japan Science and Technology Agency , 4-1-8 Honcho, Kawaguchi-shi, Saitama 322-0012, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Yamakata
authors.affiliation: Department of Chemistry, School of Science, Tokyo Institute of Technology , 2-12-1-NE-2 Ookayama, Meguro-ku, Tokyo 152-8550, Japan.
authors.forename: Osamu
authors.initials: O
authors.lastname: Ishitani
authors.affiliation: Department of Chemistry, School of Science, Tokyo Institute of Technology , 2-12-1-NE-2 Ookayama, Meguro-ku, Tokyo 152-8550, Japan.
authors.forename: Kazuhiko
authors.initials: K
authors.lastname: Maeda