Molecular and atomic adsorptions of hydrogen, oxygen, and nitrogen on defective carbon nanotubes: A first-principles study

Abstract

To investigate the application properties of defective carbon nanotubes (CNTs) with gas adsorbates, structural and electronic properties after physical and chemical adsorptions of molecular and atomic hydrogen, oxygen and nitrogen on vacancy defects for capped single-walled carbon nanotubes (SWNTs) were simulated. The defective CNT shows the half-metal properties, but molecular chemisorption could convert the electronic property back to semiconductor. For the physisorptions of gas molecules, H2 is unstable for the endothermic process. If gas molecules approach to the defect in angstrom range, the chemisorption could happen, and oxygen molecule gains nearly 2 electrons. CNT work function drops with chemisorptions of molecular or atomic hydrogen, while oxygen behaves opposite. The weaker nitrogen chemisorption is able to keep oxygen away from adsorbing as the protective agent. The adsorption of atomic nitrogen may fill in the missing carbon atom to “repair” the defect and reduce the work function by 0.83 eV.