Vacancy-Induced Chemisorption of NO₂ on Carbon Nanotubes: A Combined Theoretical and Experimental Study

The role of structural defects on the adsorption of NO2 on carbon nanotubes (CNTs) is analyzed here by means of both statical density functional theory calculations and Car−Parrinello molecular dynamics and further confirmed by X-ray photoelectron spectroscopy measurements. The interaction of a NO2 molecule with an active site produced by a single vacancy on the sidewall follows two possible reaction routes, leading to the formation of a C−N bond or to dissociation of NO2. Accounting for defective adsorption sites allows a better understanding of microscopic mechanisms involved in technological applications of CNTs, e.g., gas-sensing devices.