Carbon Nanotubes: A Comparative Study of Synthesis Methods and Their Problems

Abstract

Carbon nanotubes (CNTs) are the backbone of nanotechnology due to their unique structural, electrical and mechanical properties. These nanostructures, which include single-layer (OSUNT) and multilayer (MSUNT) forms, are of great interest in research and industrial applications. The method of synthesis of CNTs plays a key role in their characterisation. The dominant methods for their synthesis are: chemical vapour deposition (CVD), arc discharge and laser ablation. Each technique has unique advantages and disadvantages that affect the quality, yield and scalability of the resulting nanotubes. Recent comparative studies have provided valuable information on optimising these synthesis methods. For example, changes in catalysts, precursor gases and reaction conditions significantly affect the structural integrity and purity of CNTs. This article presents a comparative analysis of these synthesis methods, highlighting key advances, the role of catalysts and the influence of process parameters. Particular attention is given to CVD-based approaches, including floating catalyst and fluidised bed methods, which show promise for large-scale production with controlled morphology. In addition, laser ablation using carbon as precursor can be a cost-effective alternative for high-throughput synthesis of OSUNTs. The aim of the study is to review CNT synthesis methods for various scientific and technological applications.