Chemistry of Lewis Acid-Base Pairs on Oxide Surfaces

We examine a large number of DFT calculations regarding the chemistry of oxide surfaces and show that their qualitative conclusions can be predicted by using a few rules derived from the Lewis acid base properties of the species involved. (1) The presence of a Lewis acid on an oxide surface increases substantially the binding energy of a Lewis base. (2) If an oxide has certain properties because it is a Lewis base, these properties can be suppressed by adsorbing a Lewis acid on the surface. (3) The presence of a Lewis base on an oxide surface diminishes the binding energy of another base, as compared to the binding energy on the same surface with no base on it. These rules also hold if the words acid and base are exchanged. We show that these rules apply to a large number of systems which seem to have no relationship to each other and which are important for catalysis by oxides.