A computational study of platinum adsorption on defective and non-defective silicon carbide nanotubes

Abstract

Platinum adsorption on the pristine, Stone–Wales defect, and vacancy defects sites in (8,0) zigzag silicon carbide nanotubes are studied based on the spin-polarized density functional theory. The formation of the Stone–Wales defects with the axial bond rotation is more favorable than the circumferential one. In addition, the vacancy of the carbon atom is more desirable than the silicon atom. The stable adsorption sites and their binding energies on different defect types are analyzed and compared to those on the perfect side wall. It is determined that the adsorption of Pt atom on nine-membered ring in carbon vacancy defect is the most exothermic site. Thus, the presence of intrinsic defects can enhance the reactivity of silicon carbide nanotubes toward Pt atom. Furthermore, the dangling bonds are the main driving force in preventing Pt atom from clustering. It is noticeable that the systems with Pt atom remained semiconductor with direct band gaps. Pt atom on pristine and vacancy-defective silicon carbide nanotubes were positively charged, whereas on Stone–Wales structures, Pt atom gained some charge. In addition, only silicon vacancy structure as structure without Pt atom showed ferromagnetic ordering, while all the systems in presence of Pt atom exhibited non-magnetic moment.