The Gibbs free energy differences (∆Grela) of
interaction CO molecule with CNT and DNTs with p and d configurations
are shown in Table 2. As shown in table 2, the difference of energy
between CNT-d and CNT-p is 53.54 kcal/mol in the gas phase, so the p
configuration is more stable than d configuration in simple CNT. Also,
the p configuration of SCNT is more stable than d configuration, 9.35
kcal/mol. In contrast, the d configuration of NCNT is more stable than
the p configuration, 53.89 kcal/mol. The ∆Grela of BCNT
complexes is very low and the CO molecule could be perpendicular (d) or
parallel (p) on the surface of BCNT. The results of
ΔGrela in three solvents were obtained from Gibbs free
energies of solvation in the solvents. The instructions of
ΔGrela in the solvents were similar to the gas phase,
and it is observed that the solvents did not change the stability of the
CO molecule at the surface of CNT.