Light Induced Carbon Dioxide Reduction by Water at Binuclear ZrOCoII Unit Coupled to Ir Oxide Nanocluster Catalyst

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• 作者：Wooyul Kim ; Guangbi Yuan ; Beth Anne McClure ; Heinz Frei
• 刊名：Journal of the American Chemical Society
• 出版年：2014
• 出版时间：August 6, 2014
• 年：2014
• 卷：136
• 期：31
• 页码：11034-11042
• 全文大小：402K
• ISSN：1520-5126

文摘

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鈥揑rO_x units in the SBA-15 pores loaded with a mixture of ¹³CO₂ and H₂O vapor resulted in the formation of ¹³CO and O₂ monitored by FT-IR and mass spectroscopy, respectively. Use of ¹⁸O labeled water resulted in the formation of ¹⁸O₂ 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.