Growth Model, Synthesis of Carbon Nanostructures and Alteration of Surface Properties Using Them

Flame synthesis is recognized as a much cheaper and higher throughput process for carbon nanotube/nanofiber (CNT/CNF) production compared to conventional catalytic processes like chemical vapor deposition (CVD). Nanostructured carbon materials, such as carbon nanotubes and nanofibers, exhibit superhydrophobic behavior over a range of pH values, including for corrosive liquids. Part of this research reports the development of a rapid on-demand process for the synthesis of superhydrophobic surfaces on silicon (Si) discs using an ethylene-air nonpremixed flame. Such superhydrophobic behavior, combined with increase in effective surface area due to carbon nanostructure (CNS) deposition and corresponding desirable size (nanoscale roughness) attract the growth and attachment of microbial colonies to these CNS-enhanced substrates. This has potentially high-impact application in microbial fuel cells (MiFCs) whereby stainless steel (SS) meshes coated with flame-deposited CNS are used as anodes and the electrons produced by attaching biofilms can generate electricity in a fuel cell. However, despite such and many other applications and promise of carbon nanotubes (CNTs), their production is generally based on empirical principles. There are only a few CNT formation models that predict the dependence of CNT growth on various synthesis parameters. Typically, these do not incorporate a detailed mechanistic consideration of the various processes that are involved during CNT synthesis. Herein, this need is addressed and a model is presented for catalytic CNT growth that integrates various interdependent physical and chemical mechanisms involved in CNT production. It is validated by comparing its predictions with experimental measurements for CVD synthesis of CNTs and a concise parametric study is presented. The results are extrapolated for flame synthesis that is recognized as a desirable cost-effective process for the bulk synthesis of CNTs, as already mentioned. The last part of this dissertation discusses an extension of the CNT growth model to silicon nanowire/nanowhisker (SiNW) synthesis. SiNWs are synthesized by a number of methods — catalysis by a metal (involving vapor-liquid-solid or VLS growth mode), molecular beam epitaxy, thermal evaporation and laser ablation to name a few. Our model pertains to metal-catalyzed VLS growth mode.

Name thesis:degree_name

Ph. D.

Level thesis:degree_level

doctoral

Discipline thesis:degree_discipline

Engineering Science and Mechanics

Department dc:contributor.department

Engineering Science and Mechanics

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

2008

Author dc:creator

• Naha, Sayangdev

Chair dc:contributor.committeechair

• Puri, Ishwar K.

Committee members dc:contributor.committeemember

• Lesko, John J.
• Mahajan, Roop L.
• Patil, Mayuresh J.
• Cramer, Mark S.
• Hajj, Muhammad R.

• carbon nanofibers
• catalysis
• nanotechnology
• flame synthesis
• silicon nanowires
• superhydrophobicity
• Carbon nanotubes

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Dc Identifier Other

etd-08072008-105548

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/28559