A First-Principles Study On Gas Sensitivity Of Pd Or Pt Loaded (5,5) Carbon Nanotube With A Di-Vacancy Defect To Co And No

Binding energies and geometrical and electronic structures for adsorptions of CO and NO on metal M (Pd or Pt) loaded or M and di-vacancy co-decorated (5,5) single-walled carbon nanotubes (M-CNTs or M-V-2-CNTs) are studied using a GGA-PBE method in the work. The calculated results show that the di-vacancy defect in a perfect (5,5) tube opens the band gap, makes the (5,5) tube transform from a conductor into a semiconductor, and strengthens the adsorption of metal M on the (5,5) tube. For the adsorptions of CO and NO on M-CNT and M-V-2-CNT, the CO and NO molecules can be both chemically adsorbed on loaded Pd or Pt atoms due to their active adsorption sites. NO is easily adsorbed on M-V-2-CNT because of its electron configuration with a high 27z- energy level and its adsorption significantly changes the band gap of M-V-2-CNT and makes M-V-2-CNT transform from a semiconductor to a conductor. However, the adsorption of CO can not cause the conductivity of M-V-2-CNT change. M-V-2-CNT has a good sensitivity to the NO gas, suitable as a sensor for detecting the NO gas molecule. In addition, the existence of di-vacancy defect decreases the interaction between CO or NO and Pt-CNT, which will contribute to the desorption of CO and NO gases. The work is expected to provide a theoretical basis for designing NO sensing devices.