title: Light induced carbon dioxide reduction by water at binuclear ZrOCo(II) unit coupled to Ir oxide nanocluster catalyst.
abstract: An all-inorganic polynuclear unit consisting of an oxo-bridged binuclear ZrOCo(II) group coupled to an iridium oxide nanocluster (IrO(x)) was assembled on an SBA-15 silica mesopore surface. A photodeposition method was developed that affords coupling of the IrO(x) water oxidation catalyst with the Co donor center. The approach consists of excitation of the ZrOCo(II) metal-to-metal charge-transfer (MMCT) chromophore with visible light in the presence of [Ir(acac)3] (acac: acetylacetonate) precursor followed by calcination under mild conditions, with each step monitored by optical and infrared spectroscopy. Illumination of the MMCT chromophore of the resulting ZrOCo(II)-IrO(x) units in the SBA-15 pores loaded with a mixture of (13)CO2 and H2O vapor resulted in the formation of (13)CO and O2 monitored by FT-IR and mass spectroscopy, respectively. Use of (18)O labeled water resulted in the formation of (18)O2 product. This is the first example of a closed photosynthetic cycle of carbon dioxide reduction by water using an all-inorganic polynuclear cluster featuring a molecularly defined light absorber. The observed activity implies successful competition of electron transfer between the IrO(x) catalyst cluster and the transient oxidized Co donor center with back electron transfer of the ZrOCo light absorber, and is further aided by the instant desorption of the CO and O2 product from the silica pores.
authors.affiliation: Physical Biosciences Division, Lawrence Berkeley National Laboratory, University of California , Berkeley, California 94720, United States.
authors.forename: Wooyul
authors.initials: W
authors.lastname: Kim
authors.forename: Guangbi
authors.initials: G
authors.lastname: Yuan
authors.forename: Beth Anne
authors.initials: BA
authors.lastname: McClure
authors.forename: Heinz
authors.initials: H
authors.lastname: Frei
mesh_terms: D002245:Carbon Dioxide / Q000737:chemistry*; D002384:Catalysis; D056831:Coordination Complexes / Q000737:chemistry*; D004579:Electron Transport; D007495:Iridium / Q000737:chemistry*; D008027:Light; D053758:Nanoparticles / Q000737:chemistry*; D055668:Photochemical Processes; D014867:Water / Q000737:chemistry*
chemical_list: D056831:Coordination Complexes; D014867:Water; C044458:iridium oxide; D002245:Carbon Dioxide; D007495:Iridium