Time scale and elementary steps of CO-induced disintegration of surface rhodium clusters
Time scale and elementary steps of CO-induced disintegration of surface rhodium clusters
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DOI：
10.1002/anie.200352318
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发表时间：
2003-01-01
影响因子：
16.6
通讯作者：
Iwasawa, Y
中科院分区：
文献类型：
--
作者：
Suzuki, A;Inada, Y;Iwasawa, Y
安吉街4795号国际化学版2003，42，4795-4799 DOI：10.1002/anie. 200352318 2003 Wiley-VCH Verlag GmbH & Co. KGaA，魏因海姆，在负载的金属簇/纳米颗粒催化剂中的金属位点，例如由反应气体诱导的活性结构的形成和分解的时间尺度和在表面上的动态事件中涉及的键重排的顺序。利用能量色散X射线吸收精细结构（DXAFS）对表面金属团簇和纳米颗粒进行原位时间分辨结构表征，对于在原子基础上记录它们的动力学性质是必不可少的，这一直是一个需要解决的长期挑战。我们已经成功地用DXAFS每100 ms观察到CO诱导的Rh团簇在Al_2O_3表面上的衰变过程。以前对类似表面现象的静态研究已经用IR，[1-3] XAFS，[4，5]和STM，[5，6]揭示了高度分散的Rh纳米颗粒/Al 2 O3催化剂的结构修饰，导致形成孤立的Rh（CO）CO吸附2种。DXAFS技术已被开发和改进，以提供分散的催化材料在1秒-几十秒的时间分辨率的原位结构信息。[7-25]在此，我们报告了通过时间分辨DXAFS表征Al 2 O3表面上Rh团簇的结构不完整性所发现的新问题，即团簇中和界面处动态键重排的时间尺度和顺序。
4795 Angew. Chem. Int. Ed. 2003, 42, 4795–4799 DOI: 10.1002/anie. 200352318 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim metal sites in supported metal cluster/nanoparticle catalysts, such as the time scale of formation and disintegration of the active structure induced by reaction gases and the sequence of bond rearrangements involved in the dynamic event on the surfaces. The in situ time-resolved structural characterization of surface metal clusters and nanoparticles by energydispersive X-ray absorption fine structure (DXAFS) is essential to document their dynamic property on an atomic basis, which has been a long-term challenge to be addressed. We have succeeded in observing the CO-induced disintegration process of Rh clusters on an Al2O3 surface by DXAFS every 100 ms. Previous static studies on the similar surface phenomenon have been performed by IR,[1–3] XAFS,[4, 5] and STM,[5, 6] which revealed the structural modification of highly dispersed Rh nanoparticles/Al2O3 catalysts that leads to the formation of isolated Rh (CO) 2 species by CO adsorption. The DXAFS technique has been developed and improved to provide in situ structural information on dispersed catalytic materials at a time resolution of 1 s—several 10 s.[7–25] Herein, we report novel issues found by the time-resolved DXAFS characterization of the structural disintegrity of Rh clusters on an Al2O3 surface, namely, the time scale and sequence of dynamic bond rearrangements in the clusters and at the interface.