钌辅助合成的钯纳米晶体及其光驱动苯乙烯加氢的性能研究

发布时间：2018-07-02 07:53

本文选题：钯 + 纳米晶体　；参考：《中国科学技术大学》2015年硕士论文

【摘要】：金属Pd作为加氢反应活性最好的催化剂材料之一,一直是催化加氢反应研究的重点。为进一步提高它的催化活性,研究工作集中于单分散的Pd纳米结构的尺寸调控和形貌研究。经过一系列的验证,科学家确定了Pd纳米催化剂加氢反应的活性位点在其晶体的棱角处,那么,具有尽可能多活性位点的Pd纳米晶体成为了加氢反应理想的催化剂。除了催化剂的反应活性之外,能量来源是催化反应考虑的另一个重要因素。为此,大量的尝试工作旨在利用金属纳米晶体的表面等离激元性质,从而利用太阳能驱动各类有机催化反应。然而,在溶液相中合成的Pd纳米粒子通常尺寸很小,导致其等离激元的波谱范围被限制在紫外区。拓宽其等离激元的波谱范围的方法通常有两种：增大纳米晶体的尺寸,或者破坏纳米晶体的对称性。在凹面纳米结构其角和边缘处有大量的金属原子,这些都可以作为加氢作用的活性位点。而且,相对于球形或立方块,凹面纳米结构的形貌对称性也比较低。总而言之,粒子尺寸大的的凹面纳米结构是在加氢作用中利用等离激元特性驱动有机反应的催化剂理想候选。我们发现了一种以Ru3+为辅助剂合成独特的Pd凹面纳米结构的方法。这种结构能够直接地捕获从紫外到可见范围的光,从而可以用于苯乙烯加氢反应。室温条件下,用100 mW/cm2的全谱太阳光照射,该催化剂的催化效率被证实与加热到70℃条件下的反应效率相当。如用相同尺寸的其它形貌的Pd金属纳米晶体,如纳米立方块和纳米八面体,催化的产率则相对较低。文中报道的纳米结构由于形貌对称性的减少而拥有更大的等离激元吸收截面,进而可以捕获宽频谱范围的光,这样通过光热效应增加了溶液中反应的温度。我们进一步发现在样品的棱角处拥有大量的原子,等离激元效应能够在这些地方高效的产生局部热量,这样为反应提供了具有较高温度的活性位点。总而言之,这些因素都大幅度地提高了加氢反应的催化效率。
[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.
【学位授予单位】：中国科学技术大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB383.1;O643.36

【参考文献】