Unexpected Odd–Even Oscillation in the Enhanced Chemical Activities of the Run (n = 2–14) Nanoclusters for H2O Splitting

Abstract

Nanoclusters usually display exotic physical and chemical properties due to their intriguing geometric structures in contrast to their bulk counterparts. In general, the more energetically stable the nanocluster, the weaker the reagent reacts with it; however, to date, it is still open whether all reactions are subject to such a fundamental constraint. Here, using first-principles calculations within density functional theory in consideration of van der Waals corrections and Gaussian 09 program, we investigate the energetic and kinetic properties of water molecules adsorption on small Run (n = 2–14) clusters. It is found that almost all of the studied Run clusters possess superior activities toward H2O adsorption and dissociation, due to the enlarged desorption energies and reduced dissociation barriers when compared with the bulk Ru(0001) counterpart. More interestingly, though the stabilities of Run clusters exhibit significant odd–even oscillation behavior, i.e., the even-numbered nanoclusters are dist...