Fundamental aspects of NO_x adsorption on BaO

摘要

The nature of NO_2 and nitriteitrate pairs adsorbed on BaO has been studied within the density functional theory. Size effects are investigated by comparing results for the BaO molecule, BaO clusters [(BaO)_x, x = 4,6,9,12] and BaO(100). The adsorption energies show weak dependence on size, which is a manifestation of the fast size convergence of the BaO electronic structure and the local character of the NO_2 adsorption bond. Nitriteitrate pair formation is associated with a significant energy gain. For BaO(100), the stability of the pair is insensitive to the nitrite-nitrate separation, a finding that demonstrates a surface mediated non-local mechanism of molecular pair formation on oxide surfaces. The results have implications for the understanding of NO_x storage and reduction catalysts.