Synthesis and thermoelectric power of nitrogen-doped carbon nanotubes.
We have previously shown that high-purity multiwalled carbon nanotubes (pristine MWNTs) can be prepared from a mixture of xylene-ferrocene (99 at% C:1 at% Fe) inside a quartz tube reactor operating at approximately 700 degrees C. In a similar process, approximately 3 g of melamine (C3H6N6) was introduced during the growth of MWNTs to prepare nitrogen-doped nanotubes. The structural and electronic properties of nitrogen-doped MWNTs were determined by scanning electron microscopy, high-resolution transmission electron microscopy (HRTEM), electron energy loss spectroscopy (EELS), and thermopower measurements. The individual nitrogen-doped nanotube exhibits a bamboo-like structure and comprises 6-16 tube walls, as evidenced by HRTEM studies. The EELS measurements yielded an average nitrogen content of approximately 5 at% in the doped tubes. The thermoelectric power data of nitrogen-doped MWNTs remained negative even after exposure to oxygen for an extended period of time, suggesting that nitrogen doping of MWNTs renders them n-type, consistent with scanning tunneling spectroscopic studies on similar nanotubes.
Sadanadan
B
B
Department of Physics and Astronomy, Clemson University, Clemson, South Carolina, USA.
Savage
T
T
Bhattacharya
S
S
Tritt
T
T
Cassell
Alan
A
Meyyappan
M
M
Dai
Z R
ZR
Wang
Z L
ZL
Zidan
R
R
Rao
A M
AM
D003460:Crystallization / Q000379:methods*; D004553:Electric Conductivity; D004563:Electrochemistry / Q000379:methods; D046911:Macromolecular Substances; D008422:Materials Testing / Q000379:methods; D008968:Molecular Conformation; D036103:Nanotechnology / Q000379:methods*; D037742:Nanotubes, Carbon / Q000737:chemistry* / Q000302:isolation & purification; D009584:Nitrogen / Q000737:chemistry*; D013499:Surface Properties
D046911:Macromolecular Substances; D037742:Nanotubes, Carbon; D009584:Nitrogen