Deposition of Pristine and Functionalized MWCNTs in Alumina Matrix by Sol-Gel Technique and Investigation of their Ammonia Sensing Properties

MWCNTs produced by using Chemical Vapor Deposition (CVD) technique were functionalized with nitric and sulfuric acid to ensure a good dispersion in an aqueous solution. The FTIR analysis further confirmed the presence of carboxyl and hydroxyl groups on the surface of MWCNTs after acid treatment. The two types of MWCNTs composites were prepared using pristine and functionalized MWCNTs (p‐MWCNTs and f‐ MWCNTs) in alumina matrix by sol‐gel processing and to the best of our knowledge it is a new approach in the field of CNT based ammonia gas sensors. The Raman analysis showed that both the pristine and functionalized MWCNTs retain its pristine characteristics in alumina matrix even after the sol‐gel processing. A precisional electronic circuit was developed to measure the sensing response of these two composite samples to detect ammonia gas and a detailed comparative analysis was done. While comparing the sensing performance, the functionalized MWCNTs composite sample was found to be more sensitive to ammonia gas with short response time but did not recover at room temperature because of the strong bonding between ammonia molecule and oxygen containing groups on the surface of MWCNTs.