本文選題：鈀 + 納米晶體��； 參考：《中國科學技術大學》2015年碩士論文

【摘要】：金屬Pd作為加氫反應活性最好的催化劑材料之一,一直是催化加氫反應研究的重點。為進一步提高它的催化活性,研究工作集中于單分散的Pd納米結構的尺寸調(diào)控和形貌研究。經(jīng)過一系列的驗證,科學家確定了Pd納米催化劑加氫反應的活性位點在其晶體的棱角處,那么,具有盡可能多活性位點的Pd納米晶體成為了加氫反應理想的催化劑。除了催化劑的反應活性之外,能量來源是催化反應考慮的另一個重要因素。為此,大量的嘗試工作旨在利用金屬納米晶體的表面等離激元性質,從而利用太陽能驅動各類有機催化反應。然而,在溶液相中合成的Pd納米粒子通常尺寸很小,導致其等離激元的波譜范圍被限制在紫外區(qū)。拓寬其等離激元的波譜范圍的方法通常有兩種：增大納米晶體的尺寸,或者破壞納米晶體的對稱性。在凹面納米結構其角和邊緣處有大量的金屬原子,這些都可以作為加氫作用的活性位點。而且,相對于球形或立方塊,凹面納米結構的形貌對稱性也比較低。總而言之,粒子尺寸大的的凹面納米結構是在加氫作用中利用等離激元特性驅動有機反應的催化劑理想候選。我們發(fā)現(xiàn)了一種以Ru3+為輔助劑合成獨特的Pd凹面納米結構的方法。這種結構能夠直接地捕獲從紫外到可見范圍的光,從而可以用于苯乙烯加氫反應。室溫條件下,用100 mW/cm2的全譜太陽光照射,該催化劑的催化效率被證實與加熱到70℃條件下的反應效率相當。如用相同尺寸的其它形貌的Pd金屬納米晶體,如納米立方塊和納米八面體,催化的產(chǎn)率則相對較低。文中報道的納米結構由于形貌對稱性的減少而擁有更大的等離激元吸收截面,進而可以捕獲寬頻譜范圍的光,這樣通過光熱效應增加了溶液中反應的溫度。我們進一步發(fā)現(xiàn)在樣品的棱角處擁有大量的原子,等離激元效應能夠在這些地方高效的產(chǎn)生局部熱量,這樣為反應提供了具有較高溫度的活性位點�？偠灾�,這些因素都大幅度地提高了加氫反應的催化效率。
[Abstract]:As one of the best catalyst materials for hydrogenation reaction, metal Pd has always been the focus of catalytic hydrogenation. In order to further improve its catalytic activity, the research work focused on the size regulation and morphology of monodisperse Pd nanostructures. After a series of verification, the scientists confirmed the activation of the hydrogenation of Pd nano catalyst. At the angle of the crystal, the Pd nanocrystals with as many active sites as possible have become an ideal catalyst for the hydrogenation reaction. In addition to the reactive activity of the catalyst, the energy source is another important factor in the consideration of the catalytic reaction. The properties of various organic catalysis are driven by solar energy. However, the Pd nanoparticles synthesized in the solution phase are usually small in size, causing the spectral range of the plasmon polaritons to be limited in the ultraviolet region. There are usually two ways to widen the spectral range of the plasmon polaritons: increase the size of nanocrystals, or destroy nanocrystals. Symmetry. There are a large number of metal atoms at the corners and edges of the concave nanostructures. These can all be used as active sites for hydrogenation. Moreover, the symmetry of the concave nanostructures is relatively low relative to the spherical or cubic blocks. In a word, the concave surface nanostructures with large particle size are used in hydrogenation. A catalyst ideal candidate for the organic reaction driven by the meta properties. We found a method for the synthesis of unique Pd concave nanostructures with Ru3+ as a auxiliary agent. This structure can directly capture light from ultraviolet to visible range and can be used for the hydrogenation of styrene. At room temperature, the 100 mW/cm2 full spectrum of solar light is used. The catalytic efficiency of the catalyst has been proved to be equivalent to that of heating to 70 centigrade. For example, the yield of Pd metal nanocrystals with the same size of other morphologies, such as nano cubic blocks and nanoshedron, is relatively low. The nanostructures reported in the paper have greater ISO absorption due to the reduction of symmetry of morphology. The cross section can then capture light in the wide spectrum range, thus increasing the temperature of the reaction in the solution through the photothermal effect. We further found that there is a large number of atoms at the angle of the sample, and the plasmon effect can efficiently produce local heat at these places, thus providing a higher temperature active site for the reaction. These factors greatly increase the catalytic efficiency of hydrogenation reaction.
【學位授予單位】：中國科學技術大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TB383.1;O643.36

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相關期刊論文 前1條

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本文編號：2089436