Spatially Separated Active Sites Enable Selective CO Oxidation Reaction on Oxide Catalyst.

The search for efficient non-noble-metal catalysts able to perform selective oxidation reactions is of great importance, with relevance to many catalytic processes. However, this is often hampered because the origin of the selectivity remains controversial, particularly for reactions catalyzed by oxides. Here, combining high-pressure surface imaging techniques and theoretical calculations, we identify that spatially separated active sites for O activation and H adsorption on an ultrathin MnO surface enable selective oxidation of CO over H. Theoretical calculations reveal that Mn-O pairs for H dissociation are separated from Mn-Mn pairs for the formation of adsorbed O* so that H has to surmount much higher barriers for both H dissociation and H diffusion while CO can directly react with O* following the Eley-Rideal process. Our study sheds light on the atomic-level understanding of the surface structure-dependent selective oxidation reaction on oxide catalysts.