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

Abstract

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 CeO x (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.

Enhancement of Nitrate‐to‐Ammonia on Amorphous CeOx‐Modified Cu via Tuning of Active Hydrogen Supply

“…Ce 3d spectrum (Figure S4c, Supporting Information) exhibits mixed Ce 3+ /Ce 4+ peaks, the valence shift between Ce 3+ and Ce 4+ favoring the provision of suitable valence modulation capabilities and defect vacancies. [19] The area ratio of Ce 3+ area ratio is 45.07% (Table S1, Supporting Information), according to the previous report, higher Ce 3+ concentrations represent more oxygen vacancies in the material structure. [20] Figure S4d (Supporting Information) shows the O 1s region, with peaks at 530.6 and 531.9 eV attributable to lattice oxygen and adsorbed oxygen, [21] respectively.…”

Novel Core–Shell (ε-MnO2/CeO2)@CeO2 Composite Catalyst with a Synergistic Effect for Efficient Formaldehyde Oxidation

“…The obvious contrast of the image further confirms the core−shell nanostructure of the composite catalyst (Figure 3I). 32 The first reduction peak of the C-20 catalyst appears at 231.4 °C, lower than the first reduction peak of C-0 (264.4 °C), indicating that CeO 2 activates the O activity of the catalyst. The doping of CeO 2 makes the redox peaks of the catalyst spread more and the peaks of active oxygen stronger because Ce can promote the reduction of the oxygen species adsorbed on the surface and in the lattices.…”

“…Two additional broad reduction peaks ϖ (391.4 °C) and σ (501.3 °C) are detected over C-20 in the temperature range between 360 and 540 °C, which are attributed to the reduction of surface-active oxygen from CeO 2 . The surface-active oxygen from CeO 2 plays an important role in the catalysis of the oxidation of HCHO . The first reduction peak of the C-20 catalyst appears at 231.4 °C, lower than the first reduction peak of C-0 (264.4 °C), indicating that CeO 2 activates the O activity of the catalyst.…”

“…23 Ce 4+ (CeO 2 ) has been particularly studied as one of the prominent candidates for various technological applications because of the fast mutation between the Ce 4+ and Ce 3+ oxidation states. 32 It is also a suitable tailoring compound with high oxygen storage capacity, strong interactions with deposited metals, and redox potential in the Ce 4+ /Ce 3+ cycles. 33 However, the properties and applications of CeO 2 are strongly affected by its particle size, defects, and morphology, and the synthesis of CeO 2 with controllable structures remains the bottleneck for the utilization of the material at its full potential.…”

“…The cations can also replace the six-coordinated Mn 3+ /Mn 4+ and change the coordination environment to generate oxygen vacancies or affect the bond energy of the neighboring Mn–O bond, which in turn tailors the activity of the reactive sites . Ce 4+ (CeO 2 ) has been particularly studied as one of the prominent candidates for various technological applications because of the fast mutation between the Ce 4+ and Ce 3+ oxidation states . It is also a suitable tailoring compound with high oxygen storage capacity, strong interactions with deposited metals, and redox potential in the Ce 4+ /Ce 3+ cycles .…”