Ammonia monitoring by carbon nitride nanotubes: A density functional study

The adsorption of one to three NH3 molecule(s) on the exterior surface of a carbon nitride nanotube (CNNT) has been investigated using density functional theory. It has been found that a NH3 molecule is physically adsorbed on the tube surface with adsorption energies in the range of 15.47 to 25.08 kJ/mol. The most stable obtained configuration is that in which the NH3 molecule has been adsorbed above center of a porous site of the tube surface via forming hydrogen bonds. The adsorption of the second and third NH3 molecules at the porous sites is independent of each other. Density of states analysis reveals that the intrinsic semiconductor CNNT may transform to an extrinsic n-type semiconductor with higher electrical conductance upon the adsorption of NH3 molecules. The obtained results suggest that the CNNTs may be potentially used in NH3 sensor applications. (C) 2013 Elsevier B. V. All rights reserved.