Carvajal Diaz, Mauricio (2021-12). Catalytic Reactivity and Surface Interactions During Early Stages of Single-Walled Carbon Nanotube Formation. Doctoral Dissertation.
Thesis
Critical elements in the controlled production of single-walled carbon nanotubes (SWCNTs) methods include the substrate, the catalyst metal particle, and the carbon precursor gas feed. This research targets some of the unanswered questions and hidden relations between the components of the nanotube-particle-substrate system. Highly accurate molecular simulations, along with new experimental observations and the use of high-resolution transmission electron microscopy (HRTEM), have opened the door for a deeper understanding of nanotube formation mechanisms. This dissertation proposes a new theoretical model to explain the intrinsic tube-particle diameter relation and its applicability in various experimental setups. Additionally, new work presented here explains distinct scenarios that may break the tube-particle correlation and shows oxygen as an SWCNT nucleation promoter. Finally, we expose the effect of composition fluctuations on cobalt catalyst particles reactivy using the meta-stable cobalt carbide phases. We observed that the structure-evolving catalyst particle during carbon deposition is a unique environment far from equilibrium where surface reactions and diffusion kinetics may quickly move the scale between inactive and active surfaces.
