Pd on Cu(111) studied by photoelectron diffraction

Siervo, Abner de; Soares, E.A.; Landers, Richard; Fazan, T. A.; Morais, Jonder; Kleiman, G. G.

doi:10.1016/s0039-6028(02)01097-x

Cited by 37 publications

(51 citation statements)

References 25 publications

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“…This is an extreme version of the model proposed by de Siervo et al [3] and would be supported in part by the simulations of Canzian et al [4] which show a continual mixing of the palladium into the Cu(111) surface at 600 K. In this model the palladium visibility would fall as it diffuses into the copper and the surface layers become dominated by copper. The presence of the larger palladium atoms would produce stress, which could be alleviated by the formation of a partial dislocation whereby locally a part of a plane shifts onto an hcp site and causes the twin.…”

Section: The Effect Of Annealing On Palladium Filmssupporting

confidence: 63%

“…Firstly, although there is published evidence of intermixing between copper and palladium in very thin layers [1,3] the extra visibility seen above 1ML…”

Section: Structure Of Films With Increasing Coveragementioning

confidence: 99%

“…A subsequent study [3] used angle scanned X-ray photoelectron diffraction to investigate the structure of 1 ML of palladium deposited at room temperature but with subsequent annealing at 600 K for one minute. This investigation confirmed that the system was not a simple overlayer.…”

Section: Introductionmentioning

confidence: 99%

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Ultra-thin films and surface alloying of Pd on Cu(111) investigated by medium energy ion scattering

et al. 2010

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Section: The Effect Of Annealing On Palladium Filmssupporting

confidence: 63%

“…Firstly, although there is published evidence of intermixing between copper and palladium in very thin layers [1,3] the extra visibility seen above 1ML…”

Section: Structure Of Films With Increasing Coveragementioning

confidence: 99%

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Ultra-thin films and surface alloying of Pd on Cu(111) investigated by medium energy ion scattering

et al. 2010

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“…The core-level binding energy shifts were explained in terms of charge transfer between Pd and Cu species, and have been described in many experimental and theoretical studies. 4,13,[16][17][18][19][20] However, there is still a lack of studies on PdCu nanoalloys produced by chemical reduction employing mild chemicals and conditions. Moreover, detailed investigations on the structural and electronic properties of PdCu nanoalloys with different compositions and similar sizes have not yet been reported to our knowledge.…”

Section: Introductionmentioning

confidence: 99%

Charge transfer effects on the chemical reactivity of Pd_xCu_1−xnanoalloys

et al. 2016

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aThis work reports on the synthesis and characterization of Pd x Cu 1−x (x = 0.7, 0.5 and 0.3) nanoalloys obtained via an eco-friendly chemical reduction method based on ascorbic acid and trisodium citrate.The average size of the quasi-spherical nanoparticles (NPs) obtained by this method was about 4 nm, as observed by TEM. The colloids containing different NPs were then supported on carbon in order to produce powder samples (Pd x Cu 1−x /C) whose electronic and structural properties were probed by different techniques. XRD analysis indicated the formation of crystalline PdCu alloys with a nanoscaled crystallite size. Core-level XPS results provided a fingerprint of a charge transfer process between Pd and Cu and its dependency on the nanoalloy composition. Additionally, it was verified that alloying was able to change the NP's reactivity towards oxidation and reduction. Indeed, the higher the amount of Pd in the nanoalloy, less oxidized are both the Pd and the Cu atoms in the as-prepared samples. Also, in situ XANES experiments during thermal treatment under a reducing atmosphere showed that the temperature required for a complete reduction of the nanoalloys depends on their composition. These results envisage the control at the atomic level of novel catalytic properties of such nanoalloys.

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“…The simulated pattern was obtained after a relaxation process of the atomic structure using a method based on the genetic algorithm [34]. The structure is determined in a search process for the best set of parameters that describes the agreement between theory and experiment through minimization of the reliability factor (R-factor), as described elsewhere [35]. After obtaining the best structure, some structural parameters were varied around their best values in order to assess whether these changes actually produce significant changes in the value of R-factor and also to estimate the errors associated with these parameters.…”

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confidence: 99%

Surface structure determination of black phosphorus using photoelectron diffraction

et al. 2016

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Atomic structure of single-crystalline black phosphorus was studied by high resolution synchrotron-based photoelectron diffraction (XPD). The results show that the topmost phosphorene layer in the black phosphorus is slightly displaced compared to the bulk structure and presents a small contraction in the direction perpendicular to the surface. Furthermore, the XPD results show the presence of a small buckling among the surface atoms, in agreement with previously reported scanning tunneling microscopy results. The contraction of the surface layer added to the presence of the buckling indicates an uniformity in the size of the sp 3 bonds between P atoms at the surface.Since the experimental advent of graphene [1], other 2D materials have received enormous attention due to their great potential in nanoscale devices [2]. The 2D layered materials are characterized by atoms making strong covalent in-plane bonds, but the stacking of these atomic layers resulting from relatively weak interactions of vander-Waals type. Besides graphene, other examples of 2D materials are hexagonal boron nitride (h-BN) and transition metal dichalcogenides (TMDs), for example, MoS 2 , MoSe 2 , WSe 2 , WS 2 , among others [2]. Another interesting possibility is the design of heterostructures from the stacking of different monolayers of 2D materials, with these new materials presenting distinct properties [3]. Recently, orthorhombic black phosphorus (BP), the most stable phosphorus allotrope, has emerged as a "new" promising material for applications in nanoelectronics and nanophotonics [4]. The BP is formed by a stack of phosphorus layers arranged in a honeycomb structure [5, 6] known as phosphorene. As usual in 2D materials, the phosphorene layers are held together by a weak interaction, which allows the mechanical exfoliation procedure similar to that applied to graphene [7]. However, unlike graphene, where the carbon monolayer is strictly flat, the phosphorene has a strongly puckered structure, where each phosphorene layer can be seen as a bilayer of P atoms, as shown in Fig. 1a and 1b. Within the phosphorene layer, each atom is covalently bonded to three neighbours (sp 3 hybridization), with two bonds connecting the nearest P atoms in the same plane, and the third bond conecting P atoms between the top and bottom of the phosphorene layer, as shown in Fig. 1c. Another important difference between BP and graphene is the presence of a direct band gap, which is theoretically expected to vary with the number of phosphorene layers from ∼0.3 eV for bulk BP to ∼2 eV for the single layer [8]. The theoretical position of the band gap is a subject of some controversy in the literature [9][10][11][12]. From the experimental point of view, angle-resolved photoemission (ARPES) results show that the band gap is located at the Z point of the Brillouin Zone [11,[13][14][15].Another interesting aspect involves the band gap engineering. Several theoretical results for the bulk, few layers, phosphorene and nanoribbons show that it is possible to tune the ...

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Pd on Cu(111) studied by photoelectron diffraction

Cited by 37 publications

References 25 publications

Ultra-thin films and surface alloying of Pd on Cu(111) investigated by medium energy ion scattering

Ultra-thin films and surface alloying of Pd on Cu(111) investigated by medium energy ion scattering

Charge transfer effects on the chemical reactivity of Pd_xCu_1−xnanoalloys

Surface structure determination of black phosphorus using photoelectron diffraction

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Pd on Cu(111) studied by photoelectron diffraction

Cited by 37 publications

References 25 publications

Ultra-thin films and surface alloying of Pd on Cu(111) investigated by medium energy ion scattering

Ultra-thin films and surface alloying of Pd on Cu(111) investigated by medium energy ion scattering

Charge transfer effects on the chemical reactivity of PdxCu1−xnanoalloys

Surface structure determination of black phosphorus using photoelectron diffraction

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Charge transfer effects on the chemical reactivity of Pd_xCu_1−xnanoalloys