RHEED and XPS study of Pd–Sn bimetallic system growth

Nemšák, Slavomír; Mašek, K.; Matolín, Vladimı́r

doi:10.1016/j.susc.2007.04.215

Cited by 12 publications

(2 citation statements)

References 17 publications

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“…HOPG sample consists of randomly oriented domains, all of which have the (0001) plane parallel to the surface. As a result, one can observe the diffraction spots from all the possible planes at the same time [46]. Figure 1 shows the diffraction pattern from a clean HOPG surface.…”

Section: Epitaxial Growth Of Si On Hopgmentioning

confidence: 96%

RHEED Study of the Epitaxial Growth of Silicon and Germanium on Highly Oriented Pyrolytic Graphite

Lozovoy,

Dirko,

Kukenov

et al. 2024

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Two-dimensional silicon (silicene) and germanium (germanene) have attracted special attention from researchers in recent years. At the same time, highly oriented pyrolytic graphite (HOPG) and graphene are some of the promising substrates for growing silicene and germanene. However, to date, the processes occurring during the epitaxial growth of silicon and germanium on the surface of such substrates have been poorly studied. In this work, the epitaxial growth of silicon and germanium is studied directly during the process of the molecular beam epitaxy deposition of material onto the HOPG surface by reflection high-energy electron diffraction (RHEED). In addition, the obtained samples are studied by Raman spectroscopy and scanning electron microscopy. A wide range of deposition temperatures from 100 to 800 °C is considered and temperature intervals are determined for various growth modes of silicon and germanium on HOPG. Conditions for amorphous and polycrystalline growth are distinguished. Diffraction spots corresponding to the lattice constants of silicene and germanene are identified that may indicate the presence of areas of graphene-like 2D phases during epitaxial deposition of silicon and germanium onto the surface of highly oriented pyrolytic graphite.

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Section: Epitaxial Growth Of Si On Hopgmentioning

confidence: 96%

RHEED Study of the Epitaxial Growth of Silicon and Germanium on Highly Oriented Pyrolytic Graphite

Lozovoy,

Dirko,

Kukenov

et al. 2024

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“…It is thus interesting to consider tin; its role in these systems is usually connected (correlated) with the modification of Pd d-band and consequently related with particle adsorption properties. X-ray photoelectron spectroscopy (XPS) investigation of Pd-Sn alloy indicated a strong bimetallic interaction resulting in a noble metal-like electronic structure [35][36][37][38]. Therefore, a great effort has been made to investigate bimetallic systems based on palladium and tin in order to prepare novel catalysts for various applications .…”

Section: Introductionmentioning

confidence: 99%

Preparation and Investigation of Pd and Bimetallic Pd-Sn Nanocrystals on γ-Al2O3

et al. 2021

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One of the key factors for producing highly dispersed controlled nanoparticles is the method used for metal deposition. The decomposition of metal-organic precursors is a good method for deposition of metal nanoparticles with very small sizes and narrow size distributions on the surface of various supports. The preparation process of Pd and bimetallic Pd-Sn nanoparticles supported onto γ‑Al2O3 is considered. The samples were prepared by diffusional co-impregnation of the γ‑Al2O3 support by using organometallic Pd(acac)2 and Sn(acac)2Cl2 precursors. To achieve the formation of Pd and bimetallic Pd-Sn nanoparticles on the support surface, the synthesized samples were then subjected to thermal decomposition under Ar (to decompose the organometallic bound to the surface while keeping the formed nanoparticles small) followed by an oxidation in O2 (to eliminate the organic compounds remaining on the surface) and a reduction in H2 (to reduce the nanoparticles oxidized during the previous step). A combination of methods (ICP-OES, TPR-H2, XPS, TEM/EDX) was used to compare the physical-chemical properties of the synthesized Pd and bimetallic Pd-Sn nanoparticles supported on the γ‑Al2O3. The three samples exhibit narrow size distribution with a majority on nanoparticles between 3 and 5 nm. Local EDX measurements clearly showed that the nanoparticles are bimetallic with the expected chemical composition and the measured global composition by ICP-OES. The surface composition and electronic properties of Pd and Sn on the γ-Al2O3 support were investigated by XPS, in particular the chemical state of palladium and tin after each step of thermal decomposition treatments (oxidation, reduction) by the XPS method has been carried out. The reducibility of the prepared bimetallic nanoparticles was measured by hydrogen temperature programmed reduction (TPR-H2). The temperature programmed reduction TPR-H2 experiments have confirmed the existence of strong surface interactions between Pd and Sn, as evidenced by hydrogen spillover of Pd to Sn (Pd-assisted reduction of oxygen precovered Sn). These results lead us to propose a mechanism for the formation of the bimetallic nanoparticles.

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