Towards Large Scale Production and Separation of Carbon Nanotubes

Since their discovery, carbon nanotubes (CNTs) have boosted the research and applications of nanotechnology; however, many applications of CNTs are inaccessible because they depend upon large-scale CNT production and separations. Type, chirality and diameter control of CNTs determine many of their physical properties, and such control is still not accesible. This thesis studies the early phase routes to an inexpensive approach for large-scale CNT production and the fundamentals for scalable selective reaction of HiPCo CNT separations. At the growth stage, the thesis covers a complete wet-chemistry process of catalyst and catalyst support deposition for growth of vertically aligned (VA) CNTs. A wet-chemistry preparation process has significant importance for CNT synthesis through chemical vapor deposition (CVD). CVD is by far, the most suitable and inexpensive process for large-scale CNT production when compared to other common processes such as laser ablation and arc discharge; however, its potential has been limited by low-yielding and difficult preparation processes, therefore its competitiveness has been reduced. The wet-chemistry process takes advantage of current nanoparticle technology to deposit the catalyst and the catalyst support as a thin film of nanoparticles, making the protocol simple compared to electron beam evaporation and sputtering processes. Also, an innovative simple catalyst deposition through abrasion is demonstrated. Simple friction between the catalyst and the suited substrates deposit a high enough density of metal catalyst particles for successful CNT growth. This simple approach has potential for metal catalyst deposition to grow vertical array CNTs on large surface substrates as well as to develop nano- and micro-patterns of catalyst and CNT growth. The CNTs produced from abraded catalyst have similar qualities to CNTs synthesized from evaporated catalyst. Towards separation of CNTs, UV irradiation on individually dispersed HiPCo CNTs generates auto-selective reactions in liquid phase with good control over their diameter, therefore their chirality. This technique is ideal for large-scale and continuous-process of separations of CNTs by diameter and type.