Growth and applications of ultralong carbon nanotubes
Ultralong carbon nanotubes can be formed by placing a secondary chamber within a reactor chamber to restrict a flow to provide a laminar flow. Inner shells can be successively extracted from multi-walled carbon nanotubes (MWNTs) such as by applying a lateral force to an elongated tubular sidewall at a location between its two ends. The extracted shells can have varying electrical and mechanical properties that can be used to create useful materials, electrical devices, and mechanical devices.
1. A method, comprising:
providing a first gaseous flow in a first chamber region; dividing the first gaseous flow to provide, in a second chamber region located within the first chamber region, a second gaseous flow that is less turbulent than the first gaseous flow;
forming a carbon nanotube catalyst attached to a substrate;
housing the substrate within the second chamber region; and
forming carbon nanotube, using the catalyst attached to the substrate, in a direction that is substantially parallel to a direction of the second gaseous flow.
2. The method of claim 1 , wherein forming the carbon nanotube includes forming the carbon nanotube with a length that extends from a location of a catalyst to an end of the substrate in the direction of the second gaseous flow.
3. The method of claim 1 , wherein forming the nanotube catalyst comprises:
forming a catalytic precursor including ferric chloride;
patterning the catalytic precursor onto the substrate;
calcinating the catalytic precursor; and
forming iron particles with a size and density determined by a molar concentration of the ferric chloride.
4. The method of claim 3 , wherein patterning comprises at least one of drop drying, stamping, or photolithography.
5. The method of claim 1 , wherein at least a portion of the second gaseous flow within the second chamber region has a laminar flow.
6. The method of claim 1 , comprising forming a zero flow boundary region between the first and second regions.
7. The method of claim 1 , comprising selecting a first chamber dimension relative to a second chamber dimension to provide the second gaseous flow that is less turbulent than the first gaseous flow.
8. The method of claim 1 , wherein dividing the first gaseous flow comprises placing a tube in the first chamber region to create the second chamber region within the tube such that the second gaseous flow is within the tube and is less turbulent than the first gaseous flow in the first chamber region and outside the tube.
9. The method of claim 8 , wherein the second gaseous flow within the tube proximate the substrate has a laminar flow.
10. The method of claim 1 , further comprising selecting a size of the first chamber region and the second chamber region and positioning the second chamber region in the first chamber region so that the second gaseous flow is less turbulent than the first gaseous flow.
11. The method of claim 1 , further comprising at least one of adjusting a pressure within the first chamber region or adjusting a pressure within the second chamber region.
12. The method of claim 1 , wherein a longitudinal center axis of the second chamber region is offset from a longitudinal center axis of the first chamber region.