Abstract
Carbon nanotubes are ideal model systems for studying the physics in one-dimensional nanomaterials and have significant potential as building blocks for various practical nanoscale electronic devices. It has been shown that carbon nanotubes could be useful for miniaturized electronic, mechanical, electromechanical, chemical and scanning probe devices and materials for macroscopic composites. In this investigation, we synthesized aligned carbon nanotubes on 10-nm iron thin films by chemical vapor deposition using acetylene as the carbon source, and compared the ranges of nanotube lengths and diameters grown by different reaction conditions. Under both ammonia and argon environments, dense arrays of well aligned multi-walled carbon nanotubes could be synthesized at 750 °C with 5 % acetylene. Significantly better vertical CNT alignment was observed in NH3 environment than in argon using substrates spin-coated with iron chloride solution as catalyst. SDS plays an important role by making the catalyst particles from iron chloride solution well dispersed on the substrates. Using substrates spin-coated with iron chloride solution as catalyst, vertically aligned carbon nanotubes could be synthesized in argon until the reaction temperature is raised to 800 °C with 6.6 % acetylene. Various approaches for preparing CNT/nanoparticle composites have been demonstrated. Nanoparticle-decorated nanotube heterostructures may have catalytic, electronic, optical, and magnetic applications. We have succeeded to use amine group-terminated mono- and polycyclic molecules to attach gold nanoparticles onto the surface of multi-walled carbon nanotubes through π-π interactions. Addition of a small amount of NaOH in the solution can prevent aggregation of gold nanoparticles. On the basis of UV–vis absorption studies, it is concluded that there is a strong ground state interaction between the plasmon electrons of Au nanoparticles and the π-electron cloud of 1-pyrenemethylamine. Fluorescence monitoring further confirms the presence of charge transfer and energy transfer between 1-pyrenemethylamine and gold nanoparticles and the π-π interactions between 1-pyrenemethylamine and carbon nanotubes. Similar approach can be applied to other polycyclic aromatic compounds.