Mechanisms of NH3 and NO2 detection in carbon-nanotube-based sensors: An ab initio investigation

Journal Article · Sun May 01 04:00:00 EDT 2016 · Carbon

DOI:https://doi.org/10.1016/j.carbon.2016.01.092· OSTI ID:1565426

Li, Yan; Hodak, Miroslav; Lu, Wenchang; Bernholc, J.

The mechanisms of NH3 and NO2 detection by single-walled carbon nanotube-based devices are investigated by ab initio calculations and the non-equilibrium Greens function (NEGF) methodology. While both NH3 and NO2 can physisorb to a pristine carbon nanotube, we show that their adsorption only results in small current changes through the device. For a carbon nanotube (CNT) attached to gold nanowire leads, the most sensitive detection site is at the CNT near the CNT-Au contact, where chemisorption occurs. The resulting change in electron transmission and low-bias current can lead to over 30% sensitivity. While both NH3 and NO2 can also chemisorb at the Au electrodes, their adsorption results in only a small change in the plurality of the conducting levels of the gold layers, and thus a small effect on current. In order to enhance the detection sensitivity, it is thus beneficial to mask the electrodes to prevent chemisorption. Furthermore, the length of the pure CNT segment does not strongly affect the relative sensitivity. Our results suggest that a short-CNT device with exposed contact regions and masked electrodes would have the greatest sensitivity.

• Research Organization: Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Oak Ridge Leadership Computing Facility (OLCF); North Carolina State Univ., Raleigh, NC (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• DOE Contract Number: FG02-98ER45685
• OSTI ID: 1565426
• Journal Information: Carbon, Journal Name: Carbon Journal Issue: C Vol. 101; ISSN 0008-6223
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

Chemistry
Materials Science