The adsorption of glucose molecule on single-walled carbon nanotubes (SWCNTs) is investigated by density functional theory calculations. Adsorption energies and equilibrium distances are evaluated, and glucose binding to the typical semiconducting and metallic nanotubes with various diameters and chirality are compared. We also investigated the role of the structural defects on the adsorption capability of the SWCNTs. We could observe larger adsorption energies for the larger diameters semiconducting CNTs, while the story is paradoxical for the metallic CNTs. The obtained results reveal that the adsorption energy is significantly higher for nanotubes with higher chiral angles. Finally, the adsorption energies are calculated for defected nanotubes for various configurations such as glucose molecule approaching to the pentagon, hexagon, and heptagon sites in the tube surface. We find that the respected defects have a minor contribution to the adsorption mechanism of the glucose on SWNTs. The calculation of electron transfers and the density of states supports that the electronic properties of SWCNTs do not change significantly after the gluycose molecular adsorption. Consequently, one can predict that presence of glucose would neither modify the electronic structure of the SWCNTs nor direct to a change in the conductivity of the intrinsic nanotubes.
First principles calculations based upon density functional theory (DFT) with the spin polarized generalized gradient approximation (SGGA) have been performed to study the spin polarization phenomenon induced by inserting light metals (Li, Na, K, Mg, Ca and Al) into the B 24 N 24 nanocage. The obtained binding energies show that Al and K atoms being incorporated into the B 24 N 24 nanocage can form most stable complexes while other metals might form unstable complex with positive binding energy. Spin polarization causes the modification of HOMO-LUMO energy gaps of endohedral derivatives of alkali metals as well as Al atom. The energy gap varies with the metal atom confined in B 24 N 24 cluster. However, the penetration of an Al atom into the respective nanocage needs a high barrier energy (9.45 eV), in comparison to the Li atom (1.36 eV). Our findings reveal that edohedral Al@B 24 N 24 clusters introduced as possible materials for nanoscale spintronics devices.
We have investigated the interaction between open-ended zig-zag single-walled carbon nanotube (SWCNT) and a few benzene derivatives using the first-principles van der Waals density functional (vdW-DF) method, involving full geometry optimization. Such sp (2)-like materials are typically investigated using conventional DFT methods, which significantly underestimate non-local dispersion forces (vdW interactions), therefore affecting interactions between respected molecules. Here, we considered the vdW forces for the interacting molecules that originate from the interacting π electrons of the two systems. The -0.54 eV adsorption energy reveals that the interaction of benzene with the side wall of the SWCNT is typical of the strong physisorption and comparable with the experimental value for benzene adsorption onto the graphene sheet. It was found that aromatics are physisorbed on the sidewall of perfect SWCNTs, as well as at the edge site of the defective nanotube. Analysis of the electronic structures shows that no orbital hybridization between aromatics and nanotubes occurs in the adsorption process. The results are relevant in order to identify the potential applications of noncovalent functionalized systems.
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