Negative thermoelectric power from large diameter multiwalled carbon nanotubes grown at high chemical vapor deposition temperatures

作者：Hewitt Corey A; Kaiser Alan B; Craps Matt; Czerw Richard; Carroll David L^*

来源：Journal of Applied Physics, 2013, 114(8): 083701.

DOI：10.1063/1.4819104

Multiwalled carbon nanotubes (MWNTs) have been grown using a standard chemical vapor deposition method, except for varying the growth temperature. Nanotubes grown below 770 degrees C exhibit typical positive thermoelectric powers, while those grown above have negative values. This behavior is attributed to the larger nanotube diameters observed at higher growth temperatures. Below 770 degrees C, the average nanotube diameter is about 50 nm, while above, nanotubes reach diameters of 300 nm. This increase in diameter and number of inner shells leads to the intrinsic negative thermoelectric power of the inner nanotube shells becoming larger than the positive thermoelectric power due to oxygen doping on the outer surface of the nanotube. The overall negative thermopower (about -6 mu V/K, compared to +7 mu V/K for smaller diameter nanotubes) can be understood in terms of a parallel conduction model. Our large-diameter multiwalled carbon nanotubes allow the intrinsic negative thermopower of MWNTs to be accessed without requiring specific deoxygenation treatment.

• 出版日期2013-8-28