【作者】 吕永安；

【导师】 王建国；

【作者基本信息】 浙江工业大学 ， 工业催化， 2011， 硕士

【摘要】 由于低维碳具有稳定的光学、电学、磁学等特性,这成为了很多研究领域的热点。低维碳负载金属的复合体在很多应用领域提供了独特的性质,比如生物传感器和复合体的催化剂。低维碳有机械稳定性和大的比表面积,因而作为催化剂载体具有很有应用前景。事实上,许多实验结果表明:相对于金属氧化物载体,低维碳负载贵金属或过渡金属,在一系列的反应中,具有更好的催化活性。因此,本论文研究了低维碳（碳纳米管和石墨烯）负载金属的复合材料的性质和应用。我们用了密度泛函计算方法,系统地研究了Pt和Au团簇在缺陷或完美碳纳米管上的粘附作用。在Pt团簇体系中,计算结果表明:Pt团簇在缺陷碳纳米管上的粘附能是其在完美碳纳米管上的粘附能3-4倍。在Au团簇体系中, Au团簇粘附在C原子空缺位。通过态密度分析解释了点缺陷增强Pt或Au团簇与碳纳米管的相互作用机理;Pt或Au原子与碳原子具有更强的杂化作用,说明了金属与缺陷碳纳米管之间,有较多的电荷转移,这也解释了Pt和Au团簇与缺陷碳纳米管有很强的相互作用。我们,通过密度泛函方法,研究发现B、N掺杂可以调控贵金属（Au、Ag和Pt）单体与碳纳米管上的相互作用。但是,调控机理很强地依赖于掺杂元素及金属的类型。通过金属-B的离子键相互作用,B掺杂增强了Au、Ag与碳纳米管的相互作用。由于金属与多电子N掺杂碳纳米管的碳原子所形成的共价键强于金属与完美碳纳米管的碳原子所形成的共价键,N掺杂增强了金属与掺杂碳纳米管的相互作用。我们研究了Pd/CNTs催化剂和Pd/ACs催化剂在苯乙酮的氢化反应中的选择性的不同。并且基于密度泛函计算结果,不同吸附模型解释了, Pd/CNTs催化剂和Pd/ACs催化剂对于加氢反应中具有明显不同的选择性。我们研究表明:Al或Ga掺杂能有效提高N₂O与石墨烯的相互作用;并且,垂直电场能促进N₂O在Al或Ga掺杂石墨烯上的解离。而且,在强度适中的电场中,N₂O在Al掺杂石墨烯上,能容易被解离成N₂和O₂。更多还原

【Abstract】 Low-dimensional carbon are attractive to a wide variety of research fields because of their unique optical, electrical, magnetic, and mechanical properties. The metal/low-dimensional carbon provide unique properties for many applications such as biosensors, nanodevices, and heterogeneous catalysis. Due to the mechanical stability and large surface area, Low-dimensional carbon have been regarded as a very promising catalyst support. Therefore, we investigate the properties and applications of metal/low-dimensional carbon （carbon nanotubes and graphene）.The adhesion of various sizes of Pt or Au clusters on the carbon nanotubes （CNT） with and without the point defect has been investigated by means of density functional theory （DFT）. For Pt clusters, our calculations show that the binding energies of Ptn clusters on the point defective CNT are more than three times than that on the point defective CNT. Likewise, for Au clusters, both experimental and theoretical studies show that point defects are the anchoring sites of Au nanoparticles. The mechanisms of enhanced bond between Pt or Au clusters and CNT via the point defects are explained mainly by the analysis of density of states. The stronger orbital hybridization between the Pt or Au atom and the carbon atom shows larger charge transfers on the defective CNT than on the defect free CNT, which allows the strong interaction between Pt or Au clusters and CNT.By means of density functional theory calculations, we demonstrate that the bonding between noble metal monomers and CNT can be modulated by the B-, N-doping. But the modulation mechanisms are strongly dependent on the doping element and metal. B-doping significantly enhances the adhesion of Au, Ag on CNT mainly via the formation the metal-B ionic bond. While N-doping enhance the adhesion of Au, Ag and Pt monomer on CNT due to the formation of stronger metal-carbon covalent bond than that on pristine CNT, which is caused by electron rich N-CNT.We investigate the selectivity difference between hydrogenation of acetophenone over CNT and commercial activated carbons （ACs） supported Pd catalysts, and its mechanistic study suggestes that the different adsorption modes of reaction intermediates on two kinds of catalysts are responsible for the dramatic selectivity difference.Our studies demonstrate that the doping of Al or Ga in graphene can more effectively enhance the interaction between N₂O and graphene than pristine grapheme; Meanwhile, it is found that a perpendicular electric field can promote dissociation of N₂O molecule adsorbing on the surface of Al or Ga doped grapheme. , Furthermore, the obtained result of N₂O/Al-doped graphene under different magnitude electric field suggests that N₂O molecule can be easily decomposed to N₂ and O₂ with appropriate electric field.更多还原