Adsorption of molecular iodine on the surface of sulfur-doped carbon nanotubes: theoretical study on their interactions, sensor properties, and other applications

In this work, various sulfur-doped carbon nanotubes (SCNTs) are introduced as good adsorbents for iodine. This ability can be employed in sensor, drug delivery, and chemical reactions. Adsorption energies (in gas form and three solvents) of iodine on the surface of SCNTs in various configurations were calculated using density functional theory, and the interaction energies showed that these interactions for stable configurations were exothermic, especially in the solvents. Moreover, AIM analyses confirmed the potency of this interaction, and del(2) rho values revealed that the nature of this interaction was noncovalent. NBO calculations also showed proper interaction between SCNTs and iodine. Population analyses were found to be increasing in the reactivity of SCNT-Is versus SCNTs. Moreover, the electrical conductivity of the SCNTs was increased upon the iodine adsorption and they could be used in sensor devices for iodine detection. In comparison with S-doped fullerene, adsorption values for SCNTs were more negative and SCNTs adsorbed iodine more efficiently.