Scanning tunneling microscopy studies of Mn-doped CeOx(111) interfaces

• Mn is oxidized to Mn2+ upon deposition on CeOx(111) at 300 K.
• Atomic-layer high of MnO small features are formed on CeOx(111) at 300 K.
• Two-dimensional MnO domains can be formed after heating Mn/ceria surfaces to 800 K.
• Doping ceria with Mn can form mixed Mn-Ce oxide interfaces.

The growth and structure of Mn on reducible ceria were investigated under ultrahigh vacuum conditions with X-ray photoelectron spectroscopy, low energy electron diffraction and scanning tunneling microscopy techniques. Submonolayer coverage of Mn was deposited on well-ordered CeOx(111) (1.5 < x < 2) thin films by physical vapor deposition method at room temperature. Mn is oxidized and formally in the +2 oxidation state on both fully oxidized and partially reduced ceria. Oxidation of Mn is accompanied with the reduction of ceria. STM results show the presence of atomic-layer high islands of Mn forming Mn-O-Ce linkages uniformly distributed on the ceria surface. With heating to higher temperatures, these MnO features can coalesce to form slightly larger two-dimensional structures. Our combined spectroscopy and microscopy studies demonstrate a strong interaction between Mn and ceria supports. Introduction of Mn can form mixed Mn-Ce oxides at the interface which can represent model metal-doped ceria surfaces for further examination of the chemical behavior.

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