First-principles study of NO adsorption on defective hexagonal boron nitride monolayer

Abstract

This study explored the potential of hexagonal boron nitride (h-BN) as a support for selective catalytic reduction (SCR) which means converting NOx to N2 and H2O with the aid of a catalyst. Specifically, we investigated the adsorption behavior of a NO molecule on a defective h-BN monolayer using density functional theory. Our results indicated that the initial configuration of N and O atoms over vacancy defects plays a key role in determining whether the NO molecule is adsorbed on the h-BN monolayer via covalent or ionic bonding. In the case of mono-vacancy, the ON configuration of the NO gas resulted in lower total energy (Etotal) compared with the NO configuration. Furthermore, electron localization function and Bader charge analysis, as well as projected density of states, revealed that the ON configuration over B or N vacancy resulted in chemisorption by hybridizing p-orbitals. Furthermore, the di-vacancy system led to an even lower Etotal compared with the mono-vacancy case. In particular, both N and O atoms were adsorbed chemically to the edge of vacancy defects, irrespective of the NO configurations above the di-vacancy. Our calculations revealed that the presence of vacancy defects contributed to improving the adsorption of the NO molecule to the h-BN monolayer.