Noxious gas detection using carbon nanotubes with Pd nanoparticles
- PDF / 398,795 Bytes
- 6 Pages / 595.28 x 793.7 pts Page_size
- 13 Downloads / 240 Views
NANO EXPRESS
Open Access
Noxious gas detection using carbon nanotubes with Pd nanoparticles Hyang Hee Choi1, Junmin Lee1, Ki-Young Dong2, Byeong-Kwon Ju2 and Wooyoung Lee1*
Abstract Noxious gas sensors were fabricated using carbon nanotubes [CNTs] with palladium nanoparticles [Pd NPs]. An increase in the resistance was observed under ammonia for both CNTs and CNT-Pd sensors. Under carbon monoxide [CO], the two sensors exhibited different behaviors: for CNT sensors, their resistance decreased slightly with CO exposure, whereas CNT-Pd sensors showed an increase in resistance. The sensing properties and effect of Pd NPs were demonstrated, and CNT-Pd sensors with good repeatability and fast responses over a range of concentrations may be used as a simple and effective noxious gas sensor at room temperature. Introduction Carbon nanotubes [CNTs] have a broad variety of structures that have shown applications as materials for a rapid and innovative change in the field of gas sensing [1]. CNTs have recently been proposed as chemical sensors due to their fast response and high sensitivity toward gaseous molecules. However, the chemical and physical interactions between gas molecules and sensing nanotubes are not yet completely understood [2]. Upon exposure to gas molecules, the electrical conductance of CNTs changes and the threshold voltage is shifted due to charge transfer between the semiconducting CNTs and electron-donating (H2S, NH3, CO)/electron-withdrawing (NO2) molecules. Theoretical calculations showed the binding energy of CO and NH3 to carbon nanotubes, which indicates a weak charge transfer. The conductivity change may also be caused by contact between the metal electrode and carbon nanotubes and/or the contact between carbon nanotubes [3,4]. CNT-based gas sensors offer significant advantages: unlike oxide-based sensors such as SiO2 [5] and ZnO [6] operated at high temperatures for the detection of noxious gases, CNT-based sensors have various merits ranging from a room-temperature operation to a low detection limit. On the other hand, there are several problems to overcome for their practical application. Recently, the combination of CNTs with metal nanoparticles [NPs] has
attracted much attention [7-10], given the possibility of use in electronics, as catalysts and as biochemical sensors [11-16]. Some researchers have modified CNTs with Pd NPs using chemical vapor deposition [17], sputtering [18], electron-beam evaporation, thermal evaporation [19,20], dielectrophoresis [21,22], or electrodeposition [23,24]. There have been many efforts to detect noxious gases based on CNTs. In the case of the detection of NH3, single-walled carbon nanotube [SWNT]-SnO2 sensors can detect a low concentration of 10 ppm NH3 gases at room temperature [25]. In addition, in order to improve the sensor’s response, some works have been explored with increased operation temperature [26,27]. For the detection of CO, a PANI-functionalized CNT sensor showed a reversible response to CO in the range of 100 to 500 ppm [28], and 10 ppm CO
Data Loading...
