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学科主题: 物理化学
题名: XAS Study of TiOCr Electron Pump for Water Oxidation
作者: Han HX(韩洪宪)
会议名称: 第十三届亚洲化学会
会议日期: 2009-9-13
出版日期: 2009-09-13
会议地点: Chinese
通讯作者: 韩洪宪
部门归属: 五室
主办者: Chinese Chemical Society
摘要: One of the most challenging tasks for the assembly of an artificial photosynthetic system is the development of visible light responsive water oxidation catalyst. Recently we reported that TiOCrIII hetero-binuclear unit, a metal-to-metal charge-transfer chromophore assembled on the surface of MCM-41, could act as -powered electron pump to drive water oxidation upon coupled to IrOx nanoclusters with a quantum efficiency of 13% (lower limit).1,2 For confirming and better understanding of the structure of the TiOCrIII electron pump, XANES and EXAFS analysis were performed to study the structure, geometry and stability of the TiOCrIII photocatalytic core. In Cr-K-edge XANES spectra, the loss of sharp 1s-3d transition allowed pre-edge peak due to tetrahedrally coordinated CrVI, as well as the shift of the Cr K-edge toward lower energy position revealed that Cr was reduced from CrVI to CrIII during redox coupling of CrIV with TiIII precursor. The EXAFS analyses showed that the bond length of Cr-O was elongated from 1.59 Å to 1.97 Å due to reduction of Cr from CrVI to CrIII. Curve fitting of k3-weighted FT- EXAFS spectra showed that mono CrIII containing Cr-AlMCM-41 has 4 Cr-O at a bond distance of 1.98 Å and two Cr—Si at a distance of 3.11 Å. The hetero-binuclear TiCr-Al-MCM-41 showed 1 Cr-O with a bond distance of 1.67 Å and 3-Cr-O with a bond distance of 2.01 Å in the first shell. Interestingly, curve fitting shows that the second shell contains 1 Cr—Ti with a distance of 3.14 Å and 3 Cr—Si with a distance of 2.89 Å. No significant changes of the EXAFS data after photolysis with visible light (458 nm laser) is an indication that the hetero-binuclear TiOCrIII unit is quite stable under the severe oxidizing experimental conditions. Acknowledgements: This work was supported by the Director, Office of Science, Office of Basic Energy Sciences of the US Department of Energy under Contract No. DE-AC03-76SF00098. Portions of this research were carried out at the Stanford Synchrotron Radiation Laboratory, a national user facility operated by Stanford University.
语种: 中文
内容类型: 会议论文
URI标识: http://cas-ir.dicp.ac.cn/handle/321008/113812
Appears in Collections:中国科学院大连化学物理研究所_会议论文

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Recommended Citation:
Han HX. XAS Study of TiOCr Electron Pump for Water Oxidation[C]. 见:第十三届亚洲化学会. Chinese. 2009-9-13.
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