Alibrahim, AymanSingle-walled carbon nanotubes (SWCNTs) exhibit exceptional electrical, mechanical, and optical properties, making them potential game changers for diverse applications. However, the synthesis of SWCNTs faces significant challenges, including low yield, inadequate control over catalyst particle size, and prevalent impurities. This dissertation focuses on elucidating SWCNTs' nucleation and growth mechanisms to address these challenging issues. First, I applied in-situ absorption spectroscopy to monitor the SWCNT production by chemical vapor deposition. Second, I investigated the factors affecting metal catalyst nucleation and introduced a confinement strategy that enabled a record-breaking growth rate of 4500 meters per hour for SWCNTs. Furthermore, I developed a novel “seed doping” technique to control the nucleation of metal catalysts, significantly reducing catalyst particle size and producing purer, smaller-diameter SWCNTs continuously. Finally, I explored the role of ethanol in enabling the controlled growth of double-walled carbon nanotubes by building on SWCNTs as templates.enDissertationChemistrycarbonFC-CVDnanotubesSingle-walledSWCNT