Comparison of Gas Sensors Based on Oxygen Plasma-Treated Carbon Nanotube Network Films with Different Semiconducting Contents

Abstract

We report on the effect of oxygen plasma treatment on the performance of single-wall carbon nanotube (SWCNT) NH 3 gas sensors with different semiconducting contents (66% and 90% semiconducting SWCNTs). The performance of chemical sensors based on SWCNT networks depends on the concentration of semiconducting SWCNTs (s-SWCNTs), whose conductance can be significantly modulated by the absorbed molecules and the surface functionalization. After oxygen plasma treatment, the 66% s-SWCNT sample showed an increase in sensitivity from 0.0275%/ppm to 0.1525%/ppm (5.5 times), while the 90% s-SWCNT device demonstrated an increase in sensitivity from 0.1184%/ppm to 1.5707%/ppm (13 times). These results correspond to improvements in sensitivity of 57 times and 10 times compared with pristine and plasma-treated 66% s-SWCNT samples, respectively. In addition, the plasma-treated sensors exhibited much faster response and recovery times than the pristine one. The large improvement in performance was explained by the presence of oxygen-containing functional groups and the sp 2 -sp 3 structure change of SWCNTs, which changes the binding energy while increasing the uptake of polar molecules such as NH 3 .

Toward Highly Sensitive and Energy Efficient Ammonia Gas Detection with Modified Single-Walled Carbon Nanotubes at Room Temperature

“…It can be expected that our devices based on sc-SWCNTs, which have higher sensitivity, may be used for the detection of ammonia in the sub-ppm range. A further increase in sensitivity can be achieved not by doping with N or B atoms as was proposed in the past, but rather with oxygen plasma treatment as has been demonstrated recently . This way an ultrasensitive device able to reliably detect ammonia in the whole ppb range of concentrations can be fabricated.…”

“…A further increase in sensitivity can be achieved not by doping with N or B atoms as was proposed in the past, but rather with oxygen plasma treatment as has been demonstrated recently. 44 This way an ultrasensitive device able to reliably detect ammonia in the whole ppb range of concentrations can be fabricated. This makes the SWCNT based ammonia sensors attractive as components of a single-chip sensor array for the analysis of gas mixtures 45 with a little fraction of ammonia.…”

Evaluation of Surface Cleaning Procedures in Terms of Gas Sensing Properties of Spray-Deposited CNT Film: Thermal- and O2 Plasma Treatments

“…Moreover, the pristine and t-SWNTs sensors showed incomplete recovery of their initial resistance for all concentrations. This might be attributed to a buildup of chemisorbed NH 3 on the SWNT surface, resulting in irreversible change in the resistance [ 23 ]. The sensing performances of the modified SWNTs sensors are listed in Table 3 .…”

Carbon Nanotube‐Based Chemical Sensors

“…Since the pioneering work reporting on the response of a CNTFET for ammonia and NO 2 exposures, there have been a large number of studies on the use of carbon nanotubes for sensing gases and vapors . The subject coverage includes a wide range of topics: types of nanotubes (SWCNTs, MWCNTs), doping/coating/metal loading/functionalization strategies, different gases and vapors, different transduction approaches (electrical, optical, etc.…”