Surface Modification of MWCNTs: Preparation, Characterization and Electrical Percolation Studies of MWCNTs/PVP Composite Films for Realization of Ammonia Gas Sensor Operable at Room Temperature

• Main Authors: Sakshi Sharma, K. Sengupta, S. S. Islam
• Format: Article
• Language: English
• Published: IFSA Publishing, S.L. 2011-11-01
• Series: Sensors & Transducers
• Subjects: Carbon nanotubes; Oxidization; Gas sensor; Percolation theory
• Online Access: http://www.sensorsportal.com/HTML/DIGEST/november_2011/P_884.pdf
• ISSN: 2306-8515; 1726-5479

MWCNTs produced by using Chemical Vapor Deposition (CVD) technique were oxidized using liquid phase oxidation method where, MWCNTs were treated with mixture of Sulphuric and Nitric acid (3:1).The FTIR analysis further confirmed the presence of functional groups on the surface of MWCNTs after chemical treatment. The two types of MWCNTs composites were prepared using pristine and o-MWCNTs (as conducting fillers) in poly vinyl pyrrolidone polymer matrix (insulating matrix). The Raman and SEM analysis showed that both the pristine and functionalized MWCNTs preserve its native characteristics and had a good dispersion in Polymer matrix .The electrical conductivity behavior of MWCNTs composite was studied to ensure that the concentration of MWCNTs was higher than percolation threshold for realization of resistive type gas sensor. Two ammonia gas sensors were fabricated on Mica substrate with MWCNTs polymer composite films as an active sensing element. A sophisticated electronic circuit was developed to measure the sensing response of these sensors to detect ammonia gas at room temperature and a detailed comparative analysis was done. While comparing the sensing performance, o-MWCNT/polymer composite sensors showed a much better response than the corresponding sensor under similar conditions. Thus this preliminary work proposes simpler and cheaper processes to realize NH3 sensor for room temperature applications.