Theoretical Study On Interaction And Interfacial Properties Of Carbon Nanotubes And Noble Metals

Due to their high-efficiency, stability and recycle, supported noble metal catalysts have attracted great attention and have been widely applied in industrial catalysis, microelectronic technology, photoelectric technology, environmental protection and many other fields.As a member of fullerene family, carbon nanotubes (CNTs) have unique hollow structures as well as some attractive properties. Undoubtedly, carbon nanotubes have been the most promising materials for supporting noble metals. In this dissertation, taking the perfect CNTs as fundamental model system, combining with density functional theory (DFT) calculations, we investigated the effect of different surface oxygen-containing functional groups on the interactions between noble metals with CNTs. Meanwhile, the interfacial property of CNTs and metals was emphasized.In this work, we firstly investigated the influence of oxygen-containing functional groups (-O,-OH and-COOH) on the interaction between atomic Pd and Pd tetrahedron with CNTs.Our calculated results indicated that no matter what oxygen-containing functional groups is, it can be acted as active sites for anchoring the metal atoms, with the order of reactivity being-O>-OH>-COOH. Thus, we concluded that the surface oxygen-containing functional groups can stabilize the metal catalysts on the CNTs, resulting in uniform deposition.We further focused on the interfacial properties of CNTs and metal catalysts. At first, the top, middle and interfacial sites on Pd rod and Pt rod were chosen for adsorbing H2, O2, CO and CH4. Our results indicated that the interface between CNTs and metals would weaken the adsorption of molecules. Next, we took the H2O2formation through H2and O2reaction on Au5Pd5/CNTs as an example. We pointed it out that the reaction at interface can reduce the energy barrier of OOH*and HOOH*formation, meanwhile suppress the dissociation of both of them. Also, the partial density of states (PDOS) of Pd on different sites was used to explain the high selectivity for H2O2formation, attributed to the CNTs’ ability to modulate the activity of noble metals.