Theoretical study about alkali metal adsorption on pristine and defective (8,0) SWCNT: Geometrical, magnetic and electronic changes

Abstract

In this work we performed density functional theory (DFT) calculations, analyzing the effects of adsorption of several alkali metals (AM) on pristine and defective (8,0) single-wall carbon nanotube (SWCNT). We found that after AM adsorption the semiconducting carbon nanotube (CNT) exhibit a metallic character. A linear relationship was observed between the work function (WF) and the electronegativity of the AM absorbed, increasing the WF with the electronegativity. Also, it was seen that the WF is greater in the defective than the pristine, comparing systems with the same AM absorbed. Moreover, the vacancy presence improves the adsorption of AM on the SWCNT surface in about 1.6 eV. Finally, it was observed a change in the diameter of de SWCNT, increasing in the direction of the metal-SWCNT and reducing in the perpendicular direction. The DOS curves for the defective AM-SWCNT show an asymmetry between the spin up and spin down contributions, which is consistent with an induced magnetic moment of about 1 μB. Our results show that these adatoms induce important changes in the electronic and magnetic properties of the CNT, which make this system suitable for applications on nanoelectronics, hydrogen storage, chemical sensors among others.