The nature of small molecules adsorbed on defective carbon nanotubes.

In this work, we perform a comprehensive theoretical study on adsorption of representative 10-electron molecules H2O, CH4 and NH3 onto defective single-walled carbon nanotubes. Results of adsorption energy and charge transfer reveal the existence of both chemical adsorption (CA) and physical adsorption (PA). While PA processes are common for all molecules, CA could be further achieved by the polar molecule NH3, whose lone-pair electrons makes it easier to be bonded with the defective nanotube. Our systematic work could contribute to the understanding on intermolecular interactions and the design of future molecular detectors.