The role of potassium in the activation of oxygen to promote nitric oxide oxidation on honeycomb-like h-BN(001) surfaces

Abstract

Two-dimensional materials have developed rapidly in the field of catalysis, which has made honeycomb-like 2D hexagonal boron nitride (h-BN) considered to be a promising material in the application of catalysis. In this study, potassium (K) modified h-BN(001) surfaces are designed for the first time for the purpose of removal of nitric oxide (NO) via dispersion corrected density functional theory (DFT) computations. The role of K in changing the electronic properties and processes of NO oxidation is investigated in detail. The introduction of K effectively narrows the band gap of h-BN and acts as the surface electron donor on the surface. Importantly, the energy barrier is decreased by 3.45 eV at most along the whole NO oxidation path on K-doped h-BN(001), which is directly ascribed to the spontaneous dissociation of O₂ induced by K and efficient charge transfer across the interface. The activation of O₂ may be beneficial to other analogous oxidation reactions. With the introduction of K, the energy barrier of NO₂ conversion to NO₃⁻ is significantly decreased and the desorption of NO₂ is inhibited. Hence, NO₃⁻ instead of NO₂ becomes the main oxidation product on K-modified h-BN. This work may provide new insights into the role of alkali metals in the activation of O₂ to facilitate oxidation reactions on 2D materials.