A Model for Self-Assembly of Carbon Nanotubes from Acetylene Based on Real-Time Studies of Vertically Aligned Growth Kinetics
- ORNL
Time-resolved optical reflectivity was used to study the kinetics in the early stages of vertically aligned carbon nanotube array growth from a molecular beam of acetylene. The molecular beam environment was used to suppress gas phase reaction pathways and limit the growth to surface reactions specific to the molecular structure of acetylene. The observed acetylene flux dependent induction delay and the threshold for vertically aligned growth are characteristic features of heterogeneous chain reactions. Propagation of chain reactions requires regeneration of the active sites that can occur only if catalytic activity is transferred from the metal catalyst film to surface carbon species. After the active site transformation, acetylene self-assembles into carbon structures of progressively increasing size such as chains, graphene fragments, and nanotubes. In this paper we show that a conceptual framework supported by ab initio density functional theory calculations in which active carbon species facilitate incorporation of new carbon readily explains recent results in vertically aligned nanotube growth that are puzzling in the context of the diffusion/precipitation model.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE Office of Science (SC)
- DOE Contract Number:
- DE-AC05-00OR22725
- OSTI ID:
- 975061
- Journal Information:
- Journal of Physical Chemistry C, Vol. 113, Issue 15; ISSN 1932-7447
- Country of Publication:
- United States
- Language:
- English
Similar Records
Cooperative Behavior in the Evolution of Alignment and Structure in Vertically Aligned Carbon-Nanotube Arrays Grown using Chemical Vapor Deposition
Quantum Chemical Simulations Reveal Acetylene-Based Growth Mechanisms in the Chemical Vapor Deposition Synthesis of Carbon Nanotubes