Pd(110) surface oxide structures investigated by STM and DFT

Kralj, Marko; Pertram, T.; Seriani, Nicola; Mittendorfer, Florian; Krupski, A.; Becker, Conrad; Wandelt, K.

doi:10.1016/j.susc.2008.10.008

Cited by 16 publications

(13 citation statements)

References 43 publications

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“…One of the major results originating from this research was the discovery that the transition from the metallic catalyst to the oxide does not proceed in a single step, but that the formation of the bulk oxide is often preceded by ultrathin oxide films consisting of only a few monatomic layers. In addition to the low-dimensional oxide films observed on Rh surfaces [2][3][4], similar films have been discovered on several other late transition metals, including Ru [5][6][7], Pd [8][9][10][11][12][13][14][15][16][17] and Pt [18][19][20][21][22]. The formation of the surface oxides on a metallic support is not only of academic interest, but has practical consequences: the surface oxides do not only inhibit a further oxidation of the material, but the materials display novel properties due to the lower dimensionality of the thin films [23,24].…”

Section: Introductionsupporting

confidence: 55%

Low-dimensional surface oxides in the oxidation of Rh particles

Mittendorfer

2010

J. Phys.: Condens. Matter

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The oxidation of rhodium particles leads to the formation of low-dimensional nanostructures, namely ultrathin oxide films and stripes adsorbed on the metallic surface. These structures display unique electronic and structural properties, which have been studied in detail experimentally and theoretically in recent years. In this review, the state of research on low-dimensional surface oxides formed on Rh surfaces will be discussed with a special focus on the contributions derived from computational approaches. Several points elucidating the novel properties of the surface oxides will be addressed: (i) the structural relation between the surface oxides and their bulk counterparts, (ii) the electronic properties of the low-dimensional oxide films and (iii) potential catalytic and electronic applications of the surface oxides.

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Section: Introductionsupporting

confidence: 55%

Low-dimensional surface oxides in the oxidation of Rh particles

Mittendorfer

2010

J. Phys.: Condens. Matter

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“…On the other hand, the trenches (1D depressions) guide the Pd atom diffusion preferentially along the grooves. Such anisotropic diffusion behaviour has been observed in the inverse system, namely the oxidation of Pd(110) leading to the growth of pronounced, elongated, oxide islands [ 20 ]. Thus, in the initial phase of the cluster growth, two competing processes take place: The defects, which are distributed randomly within (and only within) the trenches, will trap some Pd atoms and thereby act as heterogeneous nucleation sites.…”

Section: Resultsmentioning

confidence: 99%

Distribution of Pd clusters on ultrathin, epitaxial TiO_x films on Pt₃Ti(111)

Breinlich

Buchholz

Moors

et al. 2015

Beilstein J. Nanotechnol.

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SummaryScanning tunnelling microscopy (STM) was used to investigate the nucleation and growth of palladium clusters on two different, ultrathin, epitaxial, titania films grown on a Pt3Ti(111) surface. The first oxide phase, z'-TiOx, is anisotropic and consists of parallel stripes separated by trenches. Defects (i.e., oxygen vacancies) in this structure are confined to these trenches and act as nucleation sites. Therefore, the Pd clusters are mostly arranged in unidirectional rows along the trenches, creating a template effect. The second phase, w'-TiOx, exhibits a hexagonal, long range, (7 × 7)R21.8°, Moiré-type superstructure with fewer and shallower defects, making the template effect less discernible.

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“…These oxygen adsorption structures relate to the oxygen coverage, but the earliest study models of the Pd(110) surface were not reconstructed. Kralj et al reported a c(2 × 4)-O surface phase on Pd(110) when oxygen coverage is 1/2 ML, but a (7 × √3)-O structure with a coverage of 6/7 ML is more stable at higher chemical potentials, where the oxygen zig-zag rows are slightly rotated to reduce the surface stress. The oxidation of Pd(211) facet has been studied as a typical stepped surface, the (211) surface undergoes a reconstruction to (113)- and (335)-type facets upon exposure to oxygen at pressures from 2 × 10 –8 to 5 × 10 –5 mbar at 673 K, and a further increase in the O 2 partial pressure led to a new rearrangement into (111)- and (113)-type facets …”

Section: Introductionmentioning

confidence: 99%

Pd₄O₃ Subsurface Oxide on Pd(111) Formed during Oxygen Adsorption-Induced Surface Reconstruction and Its Activity toward Formate Oxidation Reactions

et al. 2021

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Surface reconstruction and surface oxide formation on Pd(111) facet are investigated using density functional theory calculations coupled with particle swarm optimization (PSO) algorithms, and a series of surface oxides and isomers are obtained and evaluated for the catalytic activity toward formate oxidation reactions for the first time. A globally stable Pd 4 O 3 subsurface oxide is identified on Pd(111) facet during the oxygen adsorbedinduced surface reconstruction and featured by three subsurface oxygen atoms. The Pd(111) surface during the surface reconstruction undergoes two phase transitions starting from the oxygen-adsorbed surface to the surface oxide with an activation energy barrier of 0.366 eV and then to the Pd 4 O 3 subsurface oxide with an activation energy barrier of 0.231 eV. During the formate oxidation reaction, the limiting potentials for the Pd(111) clean surface, Pd(111) oxygen-adsorbed surface, Pd 4 O 3 surface oxide, and Pd 4 O 3 subsurface oxide are 0.612, 0.232, 0.828, and 0.141 eV, respectively, indicating that the catalytic activity is suppressed when the surface is oxidized to form Pd 4 O 3 surface oxide and then enhanced as Pd 4 O 3 subsurface oxide further forms. The reconstructed Pd 4 O 3 subsurface oxide has the highest activity among various Pd 4 O x (x = 1−4) (sub)surface oxides and isomers. Overall, this work identifies a previously unknown surface reconstruction on Pd(111) facet and proposes a mechanism of oxygen-induced surface reconstruction on Pd(111) facet and a new strategy to identify active species for reconstructed electrocatalysts in the formate oxidation reactions.

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Pd(110) surface oxide structures investigated by STM and DFT

Cited by 16 publications

References 43 publications

Low-dimensional surface oxides in the oxidation of Rh particles

Low-dimensional surface oxides in the oxidation of Rh particles

Distribution of Pd clusters on ultrathin, epitaxial TiO_x films on Pt₃Ti(111)

Pd₄O₃ Subsurface Oxide on Pd(111) Formed during Oxygen Adsorption-Induced Surface Reconstruction and Its Activity toward Formate Oxidation Reactions

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Pd(110) surface oxide structures investigated by STM and DFT

Cited by 16 publications

References 43 publications

Low-dimensional surface oxides in the oxidation of Rh particles

Low-dimensional surface oxides in the oxidation of Rh particles

Distribution of Pd clusters on ultrathin, epitaxial TiOx films on Pt3Ti(111)

Pd4O3 Subsurface Oxide on Pd(111) Formed during Oxygen Adsorption-Induced Surface Reconstruction and Its Activity toward Formate Oxidation Reactions

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Product

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Distribution of Pd clusters on ultrathin, epitaxial TiO_x films on Pt₃Ti(111)

Pd₄O₃ Subsurface Oxide on Pd(111) Formed during Oxygen Adsorption-Induced Surface Reconstruction and Its Activity toward Formate Oxidation Reactions