Analysis and optimization of carbon nanotubes and graphene sensors based on adsorption-desorption kinetics

Single-walled carbon nanotubes mats and graphene have shown great potential as gas sensors. We analyze NO adsorption/sensing experiments with the kinetic Langmuir model adapted to include adsorption sites from which the molecule does not desorb. The model reproduces the available experimental data. Its fitting parameters provide information on the microscopic phenomena governing adsorption, and variation of these parameters allows the optimization of the sensitivity, detection limit, and time response of the sensors. The result reveals an optimal operating temperature before thermal desorption becomes dominant at high temperature, the potential improvement of selectivity by tuning the gate voltage in a field effect transistor configuration, and quantifies the benefits of reducing the density of defects in the sensing materials.