Functionalization of Carbon Nanotubes for Sensing Applications

Carbon nanotubes (CNTs) composed of sp2 carbon units oriented as one rolled-up graphene have provided exceptional advances in the design of chemical sensors for environmental and health monitoring. The remarkable properties of CNTs, such as high active surface area, chemical inertness, high strength, high electrical conductivity, excellent thermal stability, and low charge-transfer resistance, have made them a potential candidate for the detection of various explosive, combustible, and toxic gases, such as hydrogen sulfide (H2S), nitrogen oxides (NOx ), ozone (O3 ), and halogens (Br2 , Cl2 , and I2 ). However, CNT-based sensor shows issues like low sensitivity and slow response/recovery time due to minimum charge transfer between the pristine CNTs and target analytes. The functionalization of CNTs with metal oxides, noble metal nanoparticles, and organic semiconductors not only improves the gas sensing parameters but also enhances their selectivity toward a particular type of target analyte due to the better charge transfer between the composite and gas analytes. This book chapter focuses on the ways to create CNT-based sensors exhibiting selective responses to different target analytes, future developments in the field of chemical sensors, and the viewpoint of their commercialization. 

Keywords: Carbon nanotubes, Chemiresistive sensor, Metal phthalocyanine, Sensing mechanism, X-ray photoelectron spectroscopy.