Study of hydroxil group adsorbtion on the graphene layers 5-7 and 3-12

Theoretical study of the electronic and physical properties of the 5-7 graphene layers of T1 structural type with adsorbed hydroxyl group (-OH) ($COH-L_{5-7-T1}$) attachment types T1 and T2, as well as the graphene layer 3-12 $COH-L_{3-12}$ functionalized by -OH group with a single attachment type was carried out using the density functional theory in a generalized gradient approximation. As result of the optimization, the layer based on 3-12 graphene with a hexagonal primitive unit cell turned out to be unstable. Two functionalized layer types with monoclinic primitive unit cells based on the graphene 5-7 of the T1 structural type are stable with large lengths of carbon-carbon bonds and elementary translations compared to a pure graphene layer and a fluorine-functionalized layer. Out of these layers based on $COH-L_{5-7-T1}$, the T1 type of attachment -OH has a layer density of 1.61 mg/m${}^2$, while the layer density of the -OH attachment type T2 is 1.67 mg/m${}^2$. In the 5-7 layers with an adsorbed -OH group, the T1 type of -OH attachment has sublimation energy of 18.20 eV/(COH). The sublimation energy of T2 -OH attachment type, equal to 18.72 eV/(COH), is greater than the sublimation energy for one of the types of -OH functionalized hexagonal graphene, which indicates high thermal stability. The widths of the band gaps of the layers is 3.74 and 3.95 eV for types T1 and T2, respectively. The range of variation of the band gap widths in comparison with the range for similar 5-7 fluorografene layers is narrower with a lower upper limit and a higher lower limit.