Growth and electronic properties of thin Zn layers on Cu(111)

Ammon, Ch.; Held, Georg; Pantförder, J.; Steinrück, Hans‐Peter

doi:10.1016/s0039-6028(00)01083-9

Cited by 16 publications

(12 citation statements)

References 17 publications

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“…Such morphology can be rationalized in terms of Zn-Cu surface alloying, albeit the latter is thought to occur at higher temperatures. [12,14] Although the basal Zn(0001) surface has a much lower surface energy as compared to Cu(111) (i.e., 0.99 and 1.95 J/m 2 , calculated [30]), previous STM studies [12] of the initial stages of Zn deposition on Cu(111) provided solid evidence that Zn ad-atoms substitute Cu in the surface layer at 300 K, in agreement with DFT calculations. [31] It has previously been proposed that Zn atoms adsorb at step edges and then migrate inside the upper terrace layer until a homogeneous distribution in the surface layer is reached.…”

Section: Resultssupporting

confidence: 73%

“…[9][10][11] Also the atomic structure and the formation of the Cu−Zn surface alloy received much attention. [12][13][14] In this respect, ZnO thin films supported on Cu can be considered as well-suited model systems for studying the reaction at the interface in order to rationalize the critical role of a ZnO phase in these catalysts. Moreover, ultrathin films supported on metals may show interesting catalytic properties in their own right.…”

Section: Introductionmentioning

confidence: 99%

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Ultrathin Zn and ZnO films on Cu(111) as model catalysts

Liu

Groot

Pan

et al. 2017

Applied Catalysis A: General

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To prepare well-defined models of ZnO-based catalysts, in particular of Cu/ZnO used for methanol synthesis, we studied the structure of Zn and ZnO thin films grown on a Cu(111) single crystal surface using metal vapor deposition. Structural characterization was performed by scanning tunneling microscopy, Auger electron spectroscopy, and low-energy electron diffraction. In agreement with previous studies, Zn wets the Cu surface forming mixed surface layer depending on Zn coverage. Surface oxidation of the Zn film into ZnO, as monitored by STM, showed that the reaction starts at step edges and propagates inside the terrace at increasing temperature. However, the process is affected by Zn migration into the Cu bulk and hence the film formation critically depends on the heating rate. In another approach using Zn deposition in oxygen ambient and subsequent annealing in vacuum, the resulted films were well-ordered and showed a long-range coincidence structure, assigned to the formation of a single ZnO(0001) layer on top of Cu(111). Independent of preparations conditions, the ZnO overlayer did not cover the entire surface, leaving considerable areas exposing Cu(111) or Cu₂O/Cu(111) surface. Reactivity measurements for CO oxidation and reverse water gas shift reactions at nearly atmospheric pressures showed no promotional effects of the ZnO overlayer under conditions studied. Moreover, Zn irreversibly migrates into the Cu crystal bulk in an O₂ rich ambient, and the surface chemistry is governed, in essence, by a poorly defined Cu-oxide film. However, the ZnO/Cu model catalysts are fairly stable in a mixture of CO₂ and H₂

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Section: Resultssupporting

confidence: 73%

Section: Introductionmentioning

confidence: 99%

Ultrathin Zn and ZnO films on Cu(111) as model catalysts

Liu

Groot

Pan

et al. 2017

Applied Catalysis A: General

View full text Add to dashboard Cite

show abstract

“…The spin-orbit splitting is in good agreement with the value of 0.33 eV for atomic Zn [49]. This value is expected to increase with the Zn concentration [50] due to the increase of the overlap of the 3d orbitals associated with a larger dispersion of the 3d states. The 3d 3/2 :3d 5/2 area ratio is 0.66 ± 0.01 in agreement with the expected value.…”

Section: O 1ssupporting

confidence: 84%

Oxidation of α-brass: A photoelectron spectroscopy study

et al. 2015

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“…Zn desorption from alloy requires a larger energy, and accordingly the TPD intensity maximum shifts back toward higher temperatures. 24 4. RESULTS FOR OXIDIZED ZINC FILMS 4.1.…”

Section: Results For Metallic Zinc Filmsmentioning

confidence: 99%

Growth and Oxidation of Zinc on Cu(111)

et al. 2019

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Zinc and zinc oxide films on Cu(111) have frequently been used as inverse model catalysts to study various chemical reactions. In the present work the growth and subsequent oxidation of zinc films are investigated by scanning tunneling microscopy (STM), low-energy ion scattering (LEIS), temperature-programmed desorption (TPD), and low-energy electron diffraction (LEED). Up to monolayer coverage zinc grows as a two-dimensional film with zinc atoms continuing the face-centered cubic lattice of the copper substrate. At higher coverages layer-by-layer growth is less strictly obeyed. Stacking faults are introduced as well, indicating a transition toward a hexagonal-close-packed structure of zinc. At 300 K intermixing is found to be slow but rises when the temperature is increased. Accordingly, the continuous downshift and broadening of the zinc desorption peak with increasing submonolayer coverage are attributed to different levels of intermixing formed during the TPD temperature ramp. Postoxidation of zinc films starts at steps of zinc islands and is most effective in the temperature range from 430 to 500 K, although at temperatures beyond ≈450 K partial desorption of zinc has to be taken into account, too. At low oxygen exposures zinc forms small ZnO clusters along Zn steps, while at higher exposures continuous “bands” of ZnO develop around metallic Zn islands. These ZnO bands decompose around 650 K into zinc atoms dissolving into copper bulk and oxygen atoms forming a surface oxide with copper. Finally, bulk dissolved zinc atoms desorb at temperatures of ≈850 K and above.

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Growth and electronic properties of thin Zn layers on Cu(111)

Cited by 16 publications

References 17 publications

Ultrathin Zn and ZnO films on Cu(111) as model catalysts

Ultrathin Zn and ZnO films on Cu(111) as model catalysts

Oxidation of α-brass: A photoelectron spectroscopy study

Growth and Oxidation of Zinc on Cu(111)

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