title: Photocatalytic hydrogen evolution from carbon-neutral oxalate with 2-phenyl-4-(1-naphthyl)quinolinium ion and metal nanoparticles.
abstract: Photocatalytic hydrogen evolution has been made possible by using oxalate as a carbon-neutral electron source, metal nanoparticles as hydrogen-evolution catalysts and the 2-phenyl-4-(1-naphthyl)quinolinium ion (QuPh(+)-NA), which forms the long-lived electron-transfer state upon photoexcitation, as a photocatalyst. The hydrogen evolution was conducted in a deaerated mixed solution of an aqueous buffer and acetonitrile (MeCN) [1:1 (v/v)] by photoirradiation (λ > 340 nm). The gas evolved during the photocatalytic reaction contained H(2) and CO(2) in a molar ratio of 1:2, indicating that oxalate acts as a two-electron donor. The hydrogen yield based on the amount of oxalate reached more than 80% under pH conditions higher than 6. Ni and Ru nanoparticles as well as Pt nanoparticles act as efficient hydrogen-evolution catalysts in the photocatalytic hydrogen evolution. The photocatalyst for hydrogen evolution can be used several times without significant deactivation of the catalytic activity. Nanosecond laser flash photolysis measurements have revealed that electron transfer from oxalate to the photogenerated QuPh˙-NA˙(+), which forms a π-dimer radical cation with QuPh(+)-NA [(QuPh˙-NA˙(+))(QuPh(+)-NA)], occurs followed by subsequent electron transfer from QuPh˙-NA to the hydrogen-evolution catalyst in the photocatalytic hydrogen evolution. Oxalate acts as an efficient electron source under a wide range of reaction conditions.
authors: Department of Materials and Life Science, Division of Advanced Science and Biotechnology, Graduate School of Engineering, Osaka University, ALCA, Japan Science and Technology Agency (JST), Suita, Osaka 565-0871, Japan. yamada@chem.eng.osaka-u.ac.jp
authors: Yusuke
authors: Y
authors: Yamada
authors: Takamitsu
authors: T
authors: Miyahigashi
authors: Kei
authors: K
authors: Ohkubo
authors: Shunichi
authors: S
authors: Fukuzumi
mesh_terms: D002244:Carbon / Q000737:chemistry*; D002384:Catalysis; D004579:Electron Transport; D006859:Hydrogen / Q000737:chemistry*; D007477:Ions / Q000737:chemistry; D053768:Metal Nanoparticles / Q000737:chemistry*; D010070:Oxalates / Q000737:chemistry*; D010782:Photolysis; D011806:Quinolinium Compounds / Q000737:chemistry*; D012428:Ruthenium / Q000737:chemistry
chemical_list: D007477:Ions; D010070:Oxalates; D011806:Quinolinium Compounds; D002244:Carbon; D012428:Ruthenium; D006859:Hydrogen