Photoemission Studies of Ultrathin Sn-Layers on TiO2—x (rutile)

Eckardt, I.; Schröter, T.; Tiedtke, K.; Wagner, Norman J.

doi:10.1002/(sici)1521-4079(1998)33:1<129::aid-crat129>3.0.co;2-4

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“…The oxidation of Sn and reduction of titania are believed to occur at the cluster–support interface, given that the fraction of Sn existing as SnO x decreases with increasing Sn deposition for coverages at which most of the surface appears to already be covered by Sn clusters; similarly, there is little increase in the fraction of reduced titania above Sn coverages of 0.05 ML. Other studies of Sn layers deposited on TiO 2 have also shown that Sn grows as an oxide in the first layer . As the Sn coverage is increased, an increasing number of larger (>7 Å high) clusters are observed.…”

Section: Discussionmentioning

confidence: 80%

“…Other studies of Sn layers deposited on TiO 2 have also shown that Sn grows as an oxide in the first layer. 103 As the Sn coverage is increased, an increasing number of larger (>7 Å high) clusters are observed. Based on XPS data, these larger clusters are believed to consist primarily of metallic Sn, and it is proposed that the diffusion of Sn atoms occurs more readily after the majority of the surface is covered by SnO x islands.…”

Section: ■ Discussionmentioning

confidence: 99%

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Oxidation of Sn at the Cluster–Support Interface: Sn and Pt–Sn Clusters on TiO₂(110)

et al. 2021

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The growth of Sn and Pt–Sn clusters on TiO2(110) has been studied by scanning tunneling microscopy, X-ray photoelectron spectroscopy (XPS), low energy ion scattering (LEIS), and density functional theory (DFT). At low Sn coverages (0.02 ML), single-layer high clusters of SnO x are formed with a narrow size distribution and uniform spatial distribution. XPS experiments indicate that these clusters consist of oxidized Sn, and the corresponding reduction in the TiO2 substrate is observed. At higher Sn coverages, the surface is still dominated by two-dimensional clusters of SnO x , but larger three-dimensional clusters of metallic Sn also appear. As the Sn coverage is increased, the number of three-dimensional clusters increases, and the ratio of Sn/SnO x increases, suggesting that SnO x and reduced TiO x form at the cluster–support interface. When Pt is deposited on top of the Sn/SnO x clusters, the relatively mobile Pt atoms diffuse across the TiO2 surface and become incorporated into existing Sn/SnO x clusters. Furthermore, the addition of Pt to the Sn/SnO x clusters causes the reduction of SnO x to metallic Sn and the oxidation of Ti3+ to Ti4+; this behavior is attributed to the formation of Pt–Sn alloy clusters, which results in the diffusion of Sn away from the interface with the TiO2 support. In contrast, when Sn is deposited on an equal coverage of Pt clusters, new Sn/SnO x clusters are formed that coexist with Pt–Sn clusters. However, the surfaces of both Pt on Sn and Sn on Pt clusters are Sn-rich due to the lower surface free energy of Sn compared to Pt. DFT calculations demonstrate that M–TiO2 bonding is favored over M–M bonding for M = Sn, unlike for transition metals such as M = Pt, Au, Ni, and Co. Furthermore, the substantial charge transfer from Sn to TiO2 leads to dipole–dipole repulsion of Sn atoms that prevents agglomeration into the larger clusters that are observed for the mid-late transition metals. DFT studies also confirm that the addition of Pt to a Sn cluster results in strong Pt–Sn bond formation and diminished Sn–O interactions.

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Section: Discussionmentioning

confidence: 80%

Section: ■ Discussionmentioning

confidence: 99%

Oxidation of Sn at the Cluster–Support Interface: Sn and Pt–Sn Clusters on TiO₂(110)

et al. 2021

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Photoemission Studies of Ultrathin Sn-Layers on TiO2—x (rutile)

Cited by 1 publication

References 10 publications

Oxidation of Sn at the Cluster–Support Interface: Sn and Pt–Sn Clusters on TiO₂(110)

Oxidation of Sn at the Cluster–Support Interface: Sn and Pt–Sn Clusters on TiO₂(110)

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Photoemission Studies of Ultrathin Sn-Layers on TiO2—x (rutile)

Cited by 1 publication

References 10 publications

Oxidation of Sn at the Cluster–Support Interface: Sn and Pt–Sn Clusters on TiO2(110)

Oxidation of Sn at the Cluster–Support Interface: Sn and Pt–Sn Clusters on TiO2(110)

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Oxidation of Sn at the Cluster–Support Interface: Sn and Pt–Sn Clusters on TiO₂(110)

Oxidation of Sn at the Cluster–Support Interface: Sn and Pt–Sn Clusters on TiO₂(110)