SIMULATION OF POLYMORPHIC VARIETIES OF HEXAGONAL GRAPHENE FUNCTIONALIZED BY HYDROXYL GROUPS

Abstract

Computer simulation of the crystal and electronic structure of hexagonal graphene layers, on the surface of which hydroxyl groups, chemically adsorbed, was performed by the density functional theory method. As a result of calculations, the possibility of the stable existence of five structural varieties of COH-L6 layers was established. The layer density varies from 1,62 to 1,72 mg/m^2. The length of the hydrogen-oxygen bond varies in the range from 1,046 to 1,079 Å, and the carbon-oxygen bond-from 1,455 to 1,465 Å. The orientation of the -OH bonds relative to the surface of the layers can vary depending on the choice of the unit cell of the layer. Layer COH-L6-T4 has the minimum sublimation energy equal to 18,69 eV/(COH), and layer COH-L6-T1 has the maximum sublimation energy 18,93 eV/(COH). The electronic structure of all COH layers is characterized by the presence of a direct band gap at the Fermi energy level, varying in the range from 3,02 to 4,56 eV.

Keywords

• graphene
• chemical adsorption
• hydroxyl groups
• ab initio calculations
• crystal structure
• electronic properties
• polymorphism