Dissociation of water at the MgO(100)-water interface: Comparison of theory with experiment

Dissociative chemisorption of H2O at the MgO(100)-water interface has been investigated both experimentally and theoretically. Ln particular, metastab le impact electron spectroscopy (MIES) was used to image the density of occ upied states on the MgO(100)/Mo(100) surface for various degrees of water e xposure. After multilayer water desorption, spectral features typical of su rface hydroxyls are present. To further study the possibility of dissociati ve chemisorption of water, a theoretical and computational method called CE CILIA (combined embedded cluster at the interface with liquid approach) was used to calculate the geometry, energetics, and electronic density of stat es (DOS) for interfacial species. Consistent with experiment, our theoretic al results predict that dissociative adsorption of H2O at the MgO(100)-wate r interface is energetically more favorable than molecular adsorption. The stabilization of charged OH- and H+ interface adsorbates is due to polariza tion of the surrounding solvent.