Break-Up of Stepped Platinum Catalyst Surfaces by High CO Coverage

From Steps to Clusters When a flat surface of a single crystal is formed by cutting or cleavage, the atoms may move little from their bulk positions, or the surface may reconstruct as the atoms move to more energetically favorable positions. The adsorption of molecules can also change the energetic landscape and cause reconstruction. Tao et al. (p. 850 ; see the Perspective by Altman ) examined “stepped” platinum surfaces, the (557) and (332) surfaces in which flat terraces are connected by atomic steps. Scanning tunneling microscopy and x-ray photoelectron spectroscopy revealed a reversible breakup into nanometer-scale clusters when CO surface coverages were very high. Density functional theory calculations suggest that this new morphology increases the number of edge sites for adsorption and relieves unfavorable CO-CO repulsions.