Electronic structure and chemical reactivity of oxide-metal interfaces: MgO(100)/Ag(100)

We present an electron spectroscopy investigation of the MgO(100)/Ag(100) oxide-metal interface electronic structure. We find that the O $2p$ states strongly hybridize with the Ag $5sp$ band and only weakly with the Ag $4d$ band. As a result of these interactions, a substantial density of states with a large oxygen antibonding character is pushed above the Fermi level, determining the chemical bonding at the oxide-metal interface. One striking consequence of such an electronic structure is the strong chemical activity of the interface toward ${\mathrm{H}}_2\mathrm{O}$ dissociative chemisorption.