Worawut Muangrat, Eakgapon Gallnom, Chaisak Issro, Wolfgang Pfeiler, and Veronique Pierron-Bohnes

pp. 695 - 699

Abstract

In this research, we investigated the effect of structure and morphology of carbon nanotubes (CNTs) on nitrogen
dioxide (NO₂
) gas sensing. CNTs were synthesized by thermal chemical vapor deposition (TCVD) at different synthesis
temperatures. The structure and morphology of CNTs were investigated by various characterization tools such as scanning
electron microscopy (SEM), transmission electron microscopy (TEM) and Raman spectroscopy. The resistance changes of
CNTs were obtained upon NO₂
 gas exposure with concentrations of 600, 1,800 and 3,000 ppm at room temperature. Our
results show that the CNTs prepared at 950°C showed the highest response. We suggest that the response of CNTs to NO₂
gas depends more strongly on the interstitial area and electronic structure than on the defects of CNTs. These results are in
good agreement with the theoretical calculations on adsorption sites (surface, pore, groove and interstitial) and electronic
structure (metallic or semiconducting) reported by previous studies.