Adsorption-Based Model for Single-Wall Carbon Nanotube Response to NO₂ Gas

Abstract

ABSTRACT:In this work, the response of single-wall carbon nanotube as a resistive NO 2 sensor was investigated. A model was developed based on the Freundlich adsorption isotherm and a multi-exponential function was used to describe the relationship between the sensor response and the gas concentration. The model predicts both static and dynamic responses in a closed sampling system. In addition, the model considers the effect of different variables such as the operating temperature, NO 2 concentration in air and the two phases (adsorption and desorption) of response. The developed model is in good accordance with the experimental data. This model could be used to design new environmental detection devices and interpret experimental data by providing some insight into the sensor behaviour during the transient phase.

Carbon Nanotube‐Based Chemical Sensors

“…A major issue in sensor development impeding further progress is the lack of understanding of sensing mechanisms, and modeling based on first principles is expected to provide the much needed insight. For example, DFT calculations were used to predict the interaction between SWCNTs and boron atoms to establish the dependence of sensitivity to CO, NO and H 2 on the dopant concentration.…”

Effective and Robust Parameter Identification Procedure of a Two-Site Langmuir Kinetics Model for a Gas Sensor Process

“…Currently, the adsorption–desorption kinetics curves and transient response curves are widely analyzed by the modified single-exponential Langmuir kinetic model, ,− although increasingly many studies indicate that other less known techniques outperform it in many cases . Considering the difference in energy on the film surface, the phenomenon of two adsorption sites and a multi-exponential kinetic model were proposed by Hu et al and have been successfully applied in diverse senors. − Recently, one more form of a two-site kinetic model was established to provide microscopic information and an intermolecular-force-based model was proposed to analyze the gas response process . Undoubtedly, the mathematical modeling of gas sensors has remained the focus of this research field.…”