Oxidation of MnO(100) and NaMnO2 formation: Characterization of Mn2+ and Mn3+ surfaces via XPS and water TPD

SURFACE SCIENCE

卷:675

Article

Feng, Xu¹  Cox, David F.¹ 

[1] Virginia Polytech Inst & State Univ, Dept Chem Engn, Blacksburg, VA 24061 USA

关键词: Manganese oxide;    NaMnO2;    Water;    Carbon dioxide;    X-ray photoelectron spectroscopy;    Temperature programmed desorption;    Low energy electron diffraction;   

DOI  :  10.1016/j.susc.2018.04.022

来源: Elsevier

【 摘 要 】

The oxidation of clean and Na precovered MnO(100) has been investigated by X-ray photoelectron spectroscopy (XPS), low energy electron diffraction (LEED) and temperature programmed desorption (TPD) of adsorbed water. XPS results indicate that Mn3O4-like and Mn2O3-like surfaces can be formed by various oxidation treatments of clean and nearly-stoichiometric MnO(100), while a NaMnO2-like surface can be produced by the oxidation of MnO(100) pre-covered with multilayers of metallic Na. Water TPD results indicate that water adsorption/desorption is sensitive to the available oxidation states of surface Mn cations, and can be used to distinguish between surfaces exposing Mn2+ and Mn3+ cations, or a combination of these oxidation states. Carbon dioxide and water TPD results from the NaMnO2-like surface indicate that pre-adsorbed water blocks the uptake of CO2, while water displaces pre-adsorbed CO2. No indication of a strong reactive interaction is observed between CO2, water and the NaMnO2-like surface under the conditions of our study.

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