Abstract
In recent year, template synthesis method has been extensively adopted for fabricating a variety of carbon nanomaterials ranging from zero- to three-dimensional structures. Such as carbon nanoparticles, nanotubes, nanofibers, graphite films, and meso-porous carbons can be obtained using nanoporous templates and various hydrocarbon precursors. Although there have been so many template-synthesized carbon materials, the possibility of this technique still has not been brought into full play. In this study, several kinds of nanocarbons, like conical and disc-like nanoparticles, unusual herringbone-type nanofibers, and ultra-thin nanobelts, are produced using anodic alumina (AAO) as template and petroleum pitch or ethanol vapor as precursors. All the products with characteristic morphologies or microstructures are prepared and characterized for the first time.Microstructural study on carbon nanocones obtained by mechanical treatment of graphitic nanofilaments indicates that their graphene stacking form does not fully agree with the current theoretical models and has to be expounded by a modified model. Using petroleum pitch composed of irregular PAHs (polycyclic aromatic hydrocarbons) as carbon source, herringbone-type carbon nanofibers constructed by conical graphenes with progressively increasing apex angles can be synthesized due to the metastable anchoring effect. The surface anchoring state at C/C boundary has also been studied by observing the interfacial lattice arrangement between pitch and carbonaceous substrates in nanocomposites. The results demonstrate that the surface anchoring state is not only dominated by the substrate species but the degree of graphitization of carbon substrates is also a key factor. A quantitative method for predicting the resulting orientation at C/C interface has been developed using average ID/IG ratio from Raman spectra. Ultra-thin carbon nanobelts with extremely-high aspect ratio of 1000 : 100 : 1 (length : width : thickness) are fabricated by decomposing ethanol in the AAO via a surface reaction route. Such morphology can be taken into account in one kind of quasi-2D nanomaterials. Their turn-on voltage obtained from field emission experiment is 3.25 V/μm, which is lower than many of current quasi-2D nanocarbons.In addition, anisotropic electrical properties of vertically-aligned single-walled carbon nanotube (VA-SWNTs) films have been measured by two- and four-probe system. The conductivity of VA-SWNT films along the vertical direction is demonstrated in independence of the film thickness (conductivity: 1.11 Ω-1mm-1), whereas their sheet conductivity along the in-plane direction decreases progressively with increasing film thickness. The ratio between vertical and sheet conductivities increases from 10s to 100s in proportion to the film thickness, exhibiting the anisotropic electrical phenomenon.