Enhancement of hydrolysis in alkali ultrathin layers on metal substrates in the presence of electron confinement

Vibrational spectroscopy has been used to study the interaction at room temperature of H2O with ultrathin alkali films grown on Cu(1 1 1), Ni(1 1 1) and Ag/Ni(1 1 1). We find strongly enhanced dissociation efficiency in the monolayer regime of Na/Cu(1 1 1), indicative of an active role of the existing Na-derived quantum wells in hydrolysis. No water adsorption has been observed for alkalis (Na, K) adsorbed on Ni(1 1 1), very likely due to the absence of electron confinement in these systems. On the other hand, partial water dissociation has been revealed in K-doped silver thin layers on Ni(1 1 1), in the presence of Ag 5sp-derived quantum wells.