AVS 51st International Symposium
    Nanometer-scale Science and Technology Tuesday Sessions
       Session NS-TuP

Paper NS-TuP16
Oxygen Functionalized MWNT as Active Layer for Gas Sensing: Detection of NO@sub 2@ and NH@sub 3@

Tuesday, November 16, 2004, 4:00 pm, Room Exhibit Hall B

Session: Poster Session
Presenter: J.-J. Pireaux, LISE, Belgium
Authors: A. Felten, LISE, Belgium
R. Ionescu, Universitat Rovira i Virgili, Spain
E. Sotter, Universitat Rovira i Virgili, Spain
E. Llobet, Universitat Rovira i Virgili, Spain
X. Vilanova, Universitat Rovira i Virgili, Spain
X. Correig, Universitat Rovira i Virgili, Spain
C. Bittencourt, LISE, Belgium
J.-J. Pireaux, LISE, Belgium
Correspondent: Click to Email
Due to their large surface area, Carbon Nanotubes (CNTs) show the potential to be applied as the active material of gas sensors. However, the presence of a thick graphite-like layer at the surface of the nanotubes can rule out the sensing potentiality of this material. In this work we use inductive RF oxygen plasma to functionalize the surface of nanotubes. The influence of different plasma conditions (power, treatment time and pressure) on the functionalization of the CNT surface was studied by XPS. The analyses showed that when a too high power is applied, a chemical etching occurs at the surface and the metallic precursors used in the CNT syntheseis are exposed. On the other hand, for an optimized range of the parameters, functional groups (hydroxide, carbonyl, carboxyl) are attached to the CNT while a reduction in the amount of graphite at the CNT surface is observed. After characterization, functionalized MWNTs (Nanocyl ®) were used to form the sensitive layer of micro-hotplate gas sensors, prepared by the drop coating method. Detection of NO@sub 2@ and NH@sub 3@ concentrations as low as 500 ppb and 200 ppm, respectively, was found to be possible at ambient temperature. Plasma treatment showed to improve the sensing potentiality of CNTs by reducing the thickness of the graphite-like layer at their surface. The presence of the residual metallic catalysts at the CNTs surface proved to play an important role in sensitivity.