Computational investigation of interaction of polypyrrole on the surface of single-walled carbon nanotube.

A density functional theory investigation of adsorption of monomer, dimer and trimer forms of pyrrole on the outer surface of zigzag (7,0) single-walled carbon nanotube (SWCNT) has been reported. Geometries of the complexes were optimized using the M06-2X functional and the 6-31G(d,p) basis set. Moreover, 6-311G(d,p), cc-pVDZ and cc-pVTZ basis sets were used for the adsorption energy calculation and such energies were corrected for the basis set superposition error. Vertical ionization potential and electron affinity of the investigated system were also computed. The interaction of polypyrrole on the SWCNT surface is characterized by the stacking interaction. Adsorption (binding) energy of pyrrole on the SWCNT surface is weak, but such energy increases with the number of monomer units in the pyrrole oligomer. In the SWCNT-pyrrole complexes, the oxidation and reduction processes will take place only at the SWCNT. The influence of larger unit on the electronic properties of the complex has been detailed.