Theoretical study of oxidation of monovacancies in hexagonal boron nitride (h-BN) sheet by oxygen molecules

By performing density functional theory (DFT) calculations, we study the oxidation of monovacancies in hexagonal boron nitride (h-BN) sheet by oxygen molecules. In particular, the changes in structural, electronic, and magnetic properties of defective h-BN sheet are mainly addressed. The results indicate that the local magnetic moments of h-BN sheet would remain intact if its dangling bonds around monovacancy are not fully saturated. In contrast, because the dangling bonds of defective h-BN sheet in the lowest energy configurations are completely saturated, the magnetism of the system is mainly contributed by the adsorbed O₂. Moreover, these oxidized h-BN sheets are converted to semiconductor with various band gaps, which depends on the adsorption site and chemical bonding of O₂ on substrates. Our results may be useful to provide guidance to experimentally study the behavior of h-BN sheet under exposure to the oxygen plasma, which is necessary to estimate its stability in air.