Theoretical prediction of the mechanisms for defect healing or oxygen doping in a hexagonal boron nitride ( h-BN) sheet with nitrogen vacancies by NO molecules.

Healing defects in hexagonal boron nitride ( h-BN sheet) or doping it with oxygen can modify or restore its physical properties, which would increase its range of potential applications. Thus, it is very important to find an efficient method of healing or a BN sheet or doping it with oxygen. In this work, using density functional theory (DFT) calculations, we identified a mechanism for healing h-BN sheets with nitrogen vacancies (V) or doping BN sheets with oxygen using NO molecules. The results indicate that such reactions involve three steps: (1) the chemisorption of NO, (2) the incorporation of the N or O atom of NO into the defective h-BN sheet, and (3) the removal of the adsorbed O atom or NO molecule. We found that the proposed mechanism is theoretically possible and has the following advantages. First, the barrier is about 0.60 eV for the formation of the O-doped h-BN sheet. For the healing process, because the energy released during NO chemisorption (−4.94 eV) completely offsets the subsequent barrier (1.17 eV), a perfect h-BN sheet can easily be achieved by using NO and an h-BN sheet with V defects as reactants. Second, no catalyst is needed, and thus there is no need for a purification step to remove the catalyst. Third, NO, a toxic gas, can be used as a reactant and will then be reduced to O or NO. Fourth, NO shows high selectivity for vacancy defect sites. Our findings show that this is an effective theoretical method of synthesizing O-doped h-BN sheets or of healing defective h-BN sheets, which should prove useful in the design of h-BN sheet-based devices. [ABSTRACT FROM AUTHOR]