A theoretical study was carried out on the binding of hydrogen on small bimetallic Ag(m)Au(n) (m + n < or = 5) and pure Au(n) (n < or = 5) clusters with neutral, negative, and positive charge state. It is found that the composition and charge state of clusters have strong influence on the most favorable binding site. The adiabatic ionization potentials, electron affinities, and hydrogen binding energies of cluster hydrides increase with the Au content increasing for the given cluster size. The cationic silver-gold cluster hydrides prefer ejection of Au-containing products whereas the anionic silver-gold cluster hydrides prefer ejection of Ag-containing products. The magnitude of metal-H frequency in combination with the metal-H bond length indicates that, with the same type of the binding site, the Au-H interaction is stronger than the Ag-H interaction.

Density functional theory calculations were performed to investigate the structural and energetic properties of trimetallic AuPdPt clusters with x + y + z = 7. The possible stable geometrical configurations with their electronic states are determined. We analyze the chemical order, binding energies, vertical ionization potential, electron affinity, and HOMO-LUMO gaps as a function of the whole concentration range. The affinity of AuPdPt clusters toward one O molecule is also evaluated in terms of the changes in geometry, adsorption energy, and charge transfer.

Density functional theory calculations were performed to investigate the molecular adsorption behaviors of hydrogen on small bimetallic Au n Cu m clusters with n ? m B 5. H 2 prefers to bind to a copper atom in Au n Cu m H 2 complexes when both Au and Cu sites co-exist. The adsorption energies of Au n H 2 are larger than Cu n H 2 clusters with the same n and the adsorption energies of bimetallic cluster hydrides are between those of mono Au n H 2 and Cu n H 2 . The adsorption of H 2 on Au n Cu m can enhance the stability of the whole cluster. The vertical ionization potentials of the cluster hydrides generally decrease as the Cu content increases for the given cluster size. The H-H and M-H stretching frequencies (M = Au or Cu) are highly correlated to the atoms to which the adsorbate is attached. The reaction paths for H 2 dissociation on AuCu, Au 2 Cu and AuCu 2 clusters were also investigated and discussed.

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