Selectively strong molecular adsorption on boron nitride monolayer induced by transition metal substrate

• Contact with transition metal substrate enhances the reactivity of boron nitride.
• Only specific molecules, NO2 and O2, are strongly adsorbed with high selectivity.
• Selectively strong adsorption would provide many applications such as catalysis.

We studied adsorption of several molecules (CO, CO2, H2O, N2O, NO, NO2, and O2) on hexagonal boron nitride (h-BN) monolayers supported on transition metal (TM) surfaces, using density functional calculations. We observed that all the molecules bind very weakly on the pristine h-BN, with binding energies in the range of 0.02–0.03 eV. Interestingly, however, when h-BN is supported on the TM surface, NO2 and O2 become strongly chemisorbed on h-BN, with binding energies of >1 eV, whereas other molecules still physisorbed, with binding energies of ∼0.1 eV at most. The electron transfer from TM to pz states of h-BN played a substantial role in such strong bindings of NO2 and O2 on h-BN, as these molecules possess unpaired electrons that can interact with pz states of h-BN. Such selective molecular binding on h-BN/TM originates from the peculiar distribution of the spin-polarized highest occupied and lowest unoccupied molecular orbitals of NO2 and O2. Strong molecular adsorption and high selectivity would make the h-BN/TM system possible for a variety of applications such as catalysts and gas sensors.