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Yanggu, South Korea

Yao F.,Sungkyunkwan University | Duong D.L.,Sungkyunkwan University | Lim S.C.,Sungkyunkwan University | Yang S.B.,Wise Control Incorporation | And 5 more authors.
Journal of Materials Chemistry | Year: 2011

In spite of the technical importance of detecting environmental SO x and NOx gases, a selective detection has not been realized because of their similar chemical properties. In this report, adsorption and desorption of SO2 and NO2 gas on carbon nanotubes are investigated in terms of different humidity levels at room temperature. A random-network single walled carbon nanotube (SWCNT) resistor is constructed by a dip-pen method using a SWCNT/dichloroethane (DCE) solution. In the case of SO2 gas adsorption, the resistance increases at high humidity level (92%) and shows no obvious change at low humidity levels. On the other hand, in the case of NO2 gas adsorption, the resistance always decreases independent of moisture levels. Our density functional theory (DFT) calculations show that this selective behavior originates from cooperative charge compensation between the SO2-nH2O complex and the p-type CNT resistor. The change of response time and recovery time with different moisture levels is further investigated. This humidity-assisted gas reaction provides a simple route to detect these two gases selectively. © 2011 The Royal Society of Chemistry.

Yao F.,Sungkyunkwan Advanced Institute of Nanotechnology | Lim S.C.,Sungkyunkwan Advanced Institute of Nanotechnology | Yu W.J.,Sungkyunkwan Advanced Institute of Nanotechnology | Lee II H.,Sungkyunkwan Advanced Institute of Nanotechnology | And 6 more authors.
Journal of Physical Chemistry C | Year: 2010

vertically aligned multiwalled carbon nanotubes (MWCNTs) as an interdigital electrode were fabricated to investigate AC response to NO2 gas. The response mechanism was explained in terms of the polarization effect of gases, charge transfer by gas adsorption on CNT electrodes, and field emission current. The response was affected more by gas adsorption than by the polarization effect and field emission effect. We also found that capacitive response and the yield of device production can be significantly improved by a post-heattreatment, which can be explained by the removal of adsorbents such as moisture and/or other functional groups on the CNT surface. © 2010 American Chemical Society.

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