Observation of water dissociation on nanometer-sized FeO islands grown on Pt(1 1 1)

Adsorption and dissociation of water on nanometer-sized FeO islands on Pt(1 1 1) substrate were investigated using scanning tunneling microscopy. It is observed that the adsorbed water molecules may spontaneously dissociate into hydroxyls on the step edges of the FeO(1 1 1) islands, even at 80 K, which can be attributed to the active sites of coordinatively unsaturated Fe atoms at the step edges. These hydroxyls are found to diffuse and form chains on the FeO terrace. The formation of the oxygen vacancy chains on FeO islands indicates that the hydroxyls may desorb from the surface as H2 and H2O at room temperature.