Splitting water on metal oxide surfaces

Abstract

We have identified a class of metal oxide surfaces that are very effective in dissociating water. These oxide surfaces are characterized by having their surface O 2p level lying significantly above the valence band maximum (VBM) and within the band gap. Density functional theory is used to determine the adsorption energy per water molecule and finds that water dissociates completely at all coverages on these surfaces. Fourier transform infrared (FTIR) spectroscopy is used to verify that there is little or no molecular water present on the surface. Besides splitting water, this class of metal oxide surfaces should also be effective in splitting other kinds of hydrogen compounds. By contrast, oxides whose surface O 2p level lies buried inside the valence band are much less reactive, and water adsorbs on these surfaces in molecular form. © 2011 American Chemical Society.