The decomposition of methanol catalyzed with Rh nanoclusters supported on an ordered thin film of Al2O3/NiAl­(100) became enhanced on decreasing the size of the clusters. The decomposition of methanol (and methanol-d 4) proceeded through dehydrogenation; the formation thereby of CO became evident above 200 K, depending little on the cluster size. In contrast, the production of CO and hydrogen (deuterium) from the reaction varied notably with the cluster size. The quantity of either CO or hydrogen produced per Rh surface site was unaltered on clusters of diameter >1.5 nm and height >0.6 nm, corresponding to about 65% of methanol undergoing decomposition on adsorption in a monolayer on the clusters. For clusters of diameter <1.5 nm and height <0.6 nm, the production per Rh surface site increased with decreasing size, up to 4 times that on the large clusters or Rh(100) single-crystal surface. The reactivity was enhanced largely because, with decreasing cluster size, the activation energy for the scission of the O–H bond in the initial dehydrogenation became smaller than the activation energy for the competing desorption. The property was associated with the edge Rh atoms at the surface of small clusters.

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The adsorption and lateral interactions of CO molecules on Rh nanoclusters supported on an ordered thin film of Al2O3/NiAl(100) altered with the size of the Rh clusters.

The dissociation of water molecules absorbed on a cleaved non-polar GaN(11[combining macron]00) surface was studied primarily with synchrotron-based photoemission spectra and density-functional-theory calculations. The adsorbed water molecules are spontaneously dissociated into hydrogen atoms and hydroxyl groups at either 300 or 130 K, which implies a negligible activation energy (<11 meV) for the dissociation. The produced H and OH were bound to the surface nitrogen and gallium on GaN(11[combining macron]00) respectively. These results highlight the promising applications of the non-polar GaN(11[combining macron]00) surface in water dissociation and hydrogen generation.