Spectro-Microscopic Study of Laser-Modified Carbon Nanotubes

Abstract

In 1991, Iijima discovered the needle-like tubes insides the fullerene production through the arc-discharge evaporation method.(1) Using transmission electron microscopy (TEM), a new type of the coaxial tube, namely carbon nanotube (CNT), was observed for the first time. One-dimensional (1D) CNTs are rolled graphitic sheet with a few nanometer in diameter. The other groups demonstrated that it is possible to generate different graphitic layers axially, such as single-wall CNTs (SWCNTs), double-wall CNTs (DWCNTs), and multi-wall CNTs (MWCNTs).(2) The electronic property of these CNTs was observed to be either metallic or semiconducting.(3) As a result, scientists have devoted much attention to study the intrinsic property of different rolled models.(4) In the case of chemical environment, the sp2-hybridized carbon sheet establishes the strongly covalent C-C bond, resulting in a high mechanical strength 100 times than that of steel.(5) The outstanding mechanical property is suitable for the tip of atomic force microscopy (AFM).(6) Besides, the chemical inertness built by the stable C-C bond leads to a perfect honeycomb structure with very few defect and gas adsorption. Only a few percentage of gas adsorption gives rise to the huge change of electronic transport property on CNTs surface. Different sensitivities of transportationwith various gas species are very useful to identify for gas sensor applications.(7) The large surface area and its hollow interior lead to the potential application in the hydrogen-stored battery utilization. For the advantage of recyclable ability and the enhancement of metallic particles, CNTs is an extremely valuable for energy storage.(8) Besides, it is important for nano-electric devices due to its superior thermal conductivity (6000 Wm−1K−1 > diamond) and current capacity (109 A/cm2 100 times than that of copper wire).(9) Despite of these exceptional characteristics, it is hard to produce a specific type of CNTs and manipulate its electronic structure to fit the diverse requirements. Therefore, the chemical functionalization route that links the specific chemical group to the tubular surface for its chemical and mechanical tuning offers an attractive post-synthesis technique to tailor the properties of the CNTs to suit the applications. In other words, it offers the functions of CNTs base multiplied by a new potential performance as an integrated device.(10) The types