ADSORPTION OF ACETIC-ACID ON HYDROXYLATED NIO(111) THIN-FILMS

Ni(100) has been exposed to O-2 to form similar to 3 monolayer crystalline NiO(111) thin films and the films have been characterized by HREELS, XPS, AES and acetic acid adsorption. The NiO(111) is Ni2+-polar and contains approximately 65% of the surface nickel sites terminated by isolated OH with substantial ionic character. The hydroxyls appear to serve a stabilizing role for the thermodynamically metastable NiO(111) surface and also to provide a condensation mechanism for interaction with the acetic acid. While there are Ni2+-OHads surface sites available for adsorption, at least some of the hydroxyls associated with the NiO(111) film are occluded or otherwise inaccessible. The XP and HREEL spectral data support an assignment of adsorbate formation to a bridging acetate species.