Yong Zhang
Xi’an Jiaotong University, P R China
Title: Properties of a weakly ionized NO gas sensor based on multi-walled carbon nanotubes
Biography
Biography: Yong Zhang
Abstract
Nitric oxide NO is one of the major targets for environmental monitoring and causes environmental and human health problems. Hence, it is of significant importance to measure NO concentrations in the air. However, the existing NO sensors are limited by their low sensitivity and narrow test range. Here, a weakly ionized NO gas sensor employing multiwalled carbon nanotubes (MWCNTs) was fabricated, and its properties in NO-N2 mixture were investigated from both emission and ionization. The current Ie passing through the nanotubes cathode was found to decrease with increasing NO concentration and increase linearly in different slopes with the extracting voltage Ue. It is shown that the Schottky barrier of the MWCNTs calculated by Ie increased with NO concentration due to the adsorption of NO gas, which restrained the electron emission and consequently weakened the ionization. The positive ion currents Ic passing through the collecting electrode at different voltages of Ue were found to be monotonically decrease with increasing NO concentration which was induced by both of the reduced electron emission and the consumption of the two excited metastable states N2(A3Σu+) and N2(a′1Σu-) by NO. The sensor exhibited high sensitivity at the low temperature of 30℃. The calculated conductivity was found to be able to take place of Ic for NO detection in a wide voltage range of 80-150V Ue.