title: Light-harvesting photocatalysis for water oxidation using mesoporous organosilica.
abstract: An organic-based photocatalysis system for water oxidation, with visible-light harvesting antennae, was constructed using periodic mesoporous organosilica (PMO). PMO containing acridone groups in the framework (Acd-PMO), a visible-light harvesting antenna, was supported with [Ru(II)(bpy)3(2+)] complex (bpy = 2,2'-bipyridyl) coupled with iridium oxide (IrO(x)) particles in the mesochannels as photosensitizer and catalyst, respectively. Acd-PMO absorbed visible light and funneled the light energy into the Ru complex in the mesochannels through excitation energy transfer. The excited state of Ru complex is oxidatively quenched by a sacrificial oxidant (Na2S2O8) to form Ru(3+) species. The Ru(3+) species extracts an electron from IrO(x) to oxidize water for oxygen production. The reaction quantum yield was 0.34 %, which was improved to 0.68 or 1.2 % by the modifications of PMO. A unique sequence of reactions mimicking natural photosystem II, 1) light-harvesting, 2) charge separation, and 3) oxygen generation, were realized for the first time by using the light-harvesting PMO.
authors.affiliation: Toyota Central R&D Labs., Inc., Nagakute, Aichi 480-1192 (Japan); JST/CREST, 4-1-8 Honcho, Kawaguchi, Saitama 332-0012 (Japan); Present address: Tokyo Institute of Technology, 2-12-1-NE-2, O-okayama, Meguro-ku, Tokyo 152-8551 (Japan).
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Takeda
authors.forename: Masataka
authors.initials: M
authors.lastname: Ohashi
authors.forename: Yasutomo
authors.initials: Y
authors.lastname: Goto
authors.forename: Tetsu
authors.initials: T
authors.lastname: Ohsuna
authors.forename: Takao
authors.initials: T
authors.lastname: Tani
authors.forename: Shinji
authors.initials: S
authors.lastname: Inagaki
mesh_terms: D015082:2,2'-Dipyridyl / Q000737:chemistry; D000166:Acridines / Q000737:chemistry*; D054831:Acridones; D002384:Catalysis; D007495:Iridium / Q000737:chemistry; D008027:Light; D010084:Oxidation-Reduction; D010100:Oxygen / Q000737:chemistry*; D017319:Photosensitizing Agents / Q000737:chemistry*; D016062:Porosity; D012428:Ruthenium / Q000737:chemistry; D012822:Silicon Dioxide / Q000737:chemistry*; D014867:Water / Q000737:chemistry*
chemical_list: D000166:Acridines; D054831:Acridones; D017319:Photosensitizing Agents; D014867:Water; C044458:iridium oxide; D007495:Iridium; D015082:2,2'-Dipyridyl; C041300:acridone; D012822:Silicon Dioxide; D012428:Ruthenium; D010100:Oxygen
keywords: artificial photosynthesis; light harvesting; mesoporous materials; photochemistry; water oxidation