Tuning of vertically-aligned carbon nanotube diameter and areal density through catalyst pre-treatment.
By controlling the timing and duration of hydrogen exposure in a fixed thermal process, we tuned the diameters of carbon nanotubes (CNTs) within a vertically aligned film by a factor of 2, and tuned the areal densities by an order of magnitude. The CNT structure is correlated with the catalyst morphology, suggesting that while chemical reduction of the catalyst layer is required for growth, prolonged H2 exposure not only reduces the iron oxide and enables agglomeration of the Fe film, but also leads to catalyst coarsening. Control of this coarsening process allows tuning of CNT characteristics.
Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Gilbert D
GD
Nessim
A John
AJ
Hart
Jin S
JS
Kim
Donatello
D
Acquaviva
Jihun
J
Oh
Caitlin D
CD
Morgan
Matteo
M
Seita
Jeffrey S
JS
Leib
Carl V
CV
Thompson