Terrace site hydroxylation upon water dimer formation on monolayer NiO/Ag(100)

THIN SOLID FILMS

卷:660

Article

Arble, Chris¹  Tong, Xiao²  Giordano, Livia³  Newberg, John T.¹  Ferrari, Anna Maria⁴ 

[1] Univ Delaware, Dept Chem & Biochem, Newark, DE 19716 USA

[2] Brookhaven Natl Lab, Ctr Funct Nanomat, Upton, NY 11973 USA

[3] Univ Milano Bicocca, Dipartimento Sci Mat, I-20125 Milan, Italy

[4] Univ Torino, NIS Nanostruct Interfaces & Surfaces Ctr, Dipartimento Chim IFM, I-10125 Turin, Italy

关键词: X-ray photoelectron spectroscopy;    Density functional theory;    Nickel oxide;    Monolayer;    Water dissociation;   

DOI  :  10.1016/j.tsf.2018.06.033

来源: Elsevier

【 摘 要 】

The interaction of water vapor with monolayer NiO/Ag(100) was examined using both experimental and computational techniques. Initial film growth was characterized by scanning tunneling microscopy and low energy electron diffraction showing the formation of NiO(1 x 1). X-ray photoelectron spectroscopy (XPS) reveals that the initial film was mainly composed of NiO oxide with a small amount of hydroxyl groups (OH) attributed to the dissociation of background water vapor at highly reactive edge sites. Density functional theory (DFT) reveals that the adsorption of a water monomer on NiO/Ag(100) terrace sites prefers to be in the molecular rather than the dissociate state. XPS results indicate that upon exposing the oxide film to high water vapor pressures (maximum 333.3 Pa), extensive hydroxylation occurs which is attributed to water dissociation at terrace sites. DFT reveals that upon aggregation of water monomers to dimers at the oxide interface the dissociated dimer is energetically stable. The results herein are consistent with previous MgO/Ag(100) studies, further revealing that for certain metal oxides the formation of water dimers at the metal oxide-vapor interface is a key mechanism leading to extensive terrace site hydroxylation.

【 授权许可】

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