銠奈米粒子鍍在白金(111)晶面為基板的石墨烯上的原子結構和反應途徑：利用反射式高能電子繞射儀和光電子能譜儀之研究;Atomic Structures and Reactivity of Rhodium Nanoclusters Supported by Graphene Grown on Pt(111): A Combined RHEED and XPS Study

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题名:	銠奈米粒子鍍在白金(111)晶面為基板的石墨烯上的原子結構和反應途徑：利用反射式高能電子繞射儀和光電子能譜儀之研究;Atomic Structures and Reactivity of Rhodium Nanoclusters Supported by Graphene Grown on Pt(111): A Combined RHEED and XPS Study
作者:	詹偉森;Wilson, James
贡献者:	物理學系
关键词:	原子結構;石墨烯;銠納米簇;鉑（111）單晶;XPS;RHEED;Atomic Structure;Graphene;Rhodium nanoclusters;Platinum (111) Single Crystal;XPS;RHEED
日期:	2018-01-30
上传时间:	2018-04-13 11:08:51 (UTC+8)
出版者:	國立中央大學
摘要:	藉由反射式高能電子繞射儀，我們檢驗了銠奈米團簇的原子結構和晶格方向，而銠的奈米團簇是藉由物理蒸鍍的方法長在以白金(111)面作為基板的石墨烯上。觀察對於方位角的強度分布，銠的奈米團簇和石墨烯有不同的晶格方向。銠的奈米團簇主要有一對的峰值，意味銠的奈米團簇有一個主要的晶格方向；這不同於石墨烯擁有兩個晶格方向。銠的奈米團簇是以面心立方成長的，而其(111)面平行於石墨烯面，呈現同於白金(111)面的晶格方向。隨著覆蓋率和溫度的變化，銠的奈米團簇的晶格常數是穩定的。為了要探測銠奈米粒子的反應力，我們用光電子能譜儀去監測一氧化碳的吸附位置、分解的反應機制、和原子碳與原子氧的形成。我們在250K吸附一氧化碳在1ML的銠奈米團簇上，然後得到了兩個氧的1s軌域的峰值在533.3和532.35eV；這隱含了一氧化碳吸附在兩個不同的吸附位置── top site和bridge site。當我們加熱到350K和450K，分子氧的訊號強度下降，原子氧的產生在531.2eV，這是一氧化碳分解的效應。再加熱到550K，所有的一氧化碳分子從銠奈米團簇表面脫附。類似的效應在2ML;By means of reflection high energy electron diffraction (RHEED), we examined the atomic structures and orientation of the Rh nanoclusters grown by vapor deposition on graphene/Pt(111). Rh nanoclusters and graphene were grown with varied orientations observed by intensity distribution as a function azimuthal angle. The Rh nanoclusters have one couple of peak dominant, indicate that the Rh nanoclusters grow with one main orientation, differently from graphene, which was found to grow with two main orientations. Rh nanoclusters are grown as FCC phase with their (111) facets parallel to the graphene surface and exhibit an orientation same as that of Pt(111). The lattice constant of Rh nanoclusters found to be stable as a function of coverage and temperature. In order to probe the reactivity of Rh nanostructures, we used XPS to monitor the CO adsorption sites, the process of dissociation, and the formation of atomic C and O. We adsorbed CO at 250 K on 1 ML Rh nanoclusters, and got two peaks of O 1s signal around 533.3 and 532.35 eV. Implying CO adsorbed at two adsorption sites which are top and bridge site. When we annealed to 350 K and 450 K, the intensity of molecular O 1s signal decreased and the production of atomic oxygen appear around 531.2 eV as the effect of CO dissociation. Further annealing to high temperature 550 K all molecular CO desorbed from the surface of Rh nanoclusters. The similar result also found on 2 ML Rh nanoclusters.
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