Abstract
This work proposes a model describing the dynamic behavior of sensing films based on functionalized MWCNT networks in terms of conductivity when exposed to time-variable concentrations of NO2 and operating with variable working temperatures. To test the proposed model, disordered networks of MWCNTs functionalized with COOH and Au nanoparticles were exploited. The model is derived from theoretical descriptions of the electronic transport in the nanotube network, of the NO2 chemisorption reaction and of the interaction of these two phenomena. The model is numerically implemented and then identified by estimating all the chemical/physical quantities involved and acting as parameters, through a model fitting procedure. Satisfactory results were obtained in the fitting process, and the identified model was used to further the analysis of the MWCNT sensing in dynamical conditions.
Highlights
The interest in using carbon nanotubes (CNTs) based materials has been continuously growing in the last years, due to their excellent physical, mechanical and electrical properties which make them suitable for various applications such as nano-optoelectronics, energy conversion systems, lithium-ion batteries production, supercapacitors, material composites and sensors, just to mention a few [1,2,3,4,5].CNTs, as carbon-based material, present a hexagonal structure made of carbon atoms forming rolled-up sheets of graphite into a cylinder shape
CNTs respond to adsorbates of different gas species, which change their electrical properties such as conductivity or permittivity, making CNTs a good solution for the realization of chemoresistive gas sensors, gaining a starring role alongside metal oxide (MOX) composites which are traditionally used in this field [11,12]
Following of the methodology followed by the authors in [28] and successfully applied to SWCNT [29], in this work we propose a model aimed at describing the conductivity of networks of MWCNTs when exposed to time-variable concentrations of NO2 and operating with variable working temperature
Summary
CNTs, as carbon-based material, present a hexagonal structure made of carbon atoms forming rolled-up sheets of graphite into a cylinder shape. The characteristic hollow shape and porous structure, the size, the large surface area and surface to volume ratio and the presence of defects, make CNTs a promising material for gas sensing layer realization [8,9,10]. CNTs respond to adsorbates of different gas species, which change their electrical properties such as conductivity or permittivity, making CNTs a good solution for the realization of chemoresistive gas sensors, gaining a starring role alongside metal oxide (MOX) composites which are traditionally used in this field [11,12]. Sensing films consisting of CNT disordered networks are gaining increasing popularity due to the facile preparation route and their good performance
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