Growth of Rh nanoclusters on TiO2(1 1 0): XPS and LEIS studies

Óvári, László; Kiss, János

doi:10.1016/j.apsusc.2005.11.081

Cited by 69 publications

(40 citation statements)

References 28 publications

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“…11. The Ti 2p emissions were symmetric; Ti 2p 3/2 appeared at 458.8 [192,193]. The spectral feature did not change significantly with time in an inert atmosphere (N 2 ).…”

Section: X-ray Photoelectron Spectroscopy (Xps)mentioning

confidence: 80%

“…Rh clusters of controlled size can be prepared by physical vapor deposition (PVD) [192,306,307] and using Rh organometallic precursors [274,308] on TiO 2 (110) as well. However, STM [306,309], XPS and LEIS [192] experiments revealed that depending on the original cluster size and the evaporation temperature, the agglomeration of Rh nanoparticles can be significant even below 500 K on that surface. The relatively small cluster sizes obtained on titanate nanowires and nanotubes may indicate that the metal diffusion on these nanobjects is limited compared to that on well-ordered titania.…”

Section: 222mentioning

confidence: 99%

See 1 more Smart Citation

Atomic scale characterization and surface chemistry of metal modified titanate nanotubes and nanowires

Kukovecz

Kordás

Kiss

2016

Surface Science Reports

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102

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Titanates are salts of polytitanic acid that can be synthesized as nanostructures in a great variety concerning crystallinity, morphology, size, metal content and surface chemistry.Titanate nanotubes (open-ended hollow cylinders measuring up to 200 nm in length and 15 nm in outer diameter) and nanowires (solid, elongated rectangular blocks with length up to 1500 nm and 30-60 nm diameter) are the most widespread representatives of the titanate nanomaterial family. This review covers the properties and applications of these two materials from the surface science point of view. Dielectric, vibrational, electron and X-ray spectroscopic results are comprehensively discussed first, then surface modification methods including covalent functionalization, ion exchange and metal loading are covered. The versatile surface chemistry of onedimensional titanates renders them excellent candidates for heterogeneous catalytic, photocatalytic, photovoltaic and energy storage applications, therefore, these fields are also reviewed.

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“…11. The Ti 2p emissions were symmetric; Ti 2p 3/2 appeared at 458.8 [192,193]. The spectral feature did not change significantly with time in an inert atmosphere (N 2 ).…”

Section: X-ray Photoelectron Spectroscopy (Xps)mentioning

confidence: 80%

Section: 222mentioning

confidence: 99%

Atomic scale characterization and surface chemistry of metal modified titanate nanotubes and nanowires

Kukovecz

Kordás

Kiss

2016

Surface Science Reports

Self Cite

102

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“…The first one was equipped with facilities for LEIS, AES, and XPS measurements (previously described in [23][24][25][26]), in the second one STM and AES techniques were used. Two similar TiO 2 (1 1 0) samples were cleaned and exposed to Au and Mo in the same way in the two UHV chambers.…”

Section: Methodsmentioning

confidence: 99%

“…XPS measurements were carried out with a constant 100 eV pass energy, at a take-off angle of 17°(with respect to surface normal) using an Al Ka X-ray anode. The binding energy scale was referenced to the position of the Ti2p emission for the stoichiometric clean oxide, set to 459.0 eV [9,13,26,32]. XP peaks were fitted using Gauss-Lorentz functions, after background subtraction (Shirley).…”

Section: Methodsmentioning

confidence: 99%

Enhanced dispersion and stability of gold nanoparticles on stoichiometric and reduced TiO2(1 1 0) surface in the presence of molybdenum

et al. 2008

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a b s t r a c tMo, Au and their coadsorbed layers were produced on nearly stoichiometric and oxygen-deficient titania surfaces by physical vapor deposition (PVD) and characterized by low energy ion scattering (LEIS), X-ray photoelectron spectroscopy (XPS), Auger electron spectroscopy (AES) and scanning tunnelling microscopy (STM). The behavior of Au/Mo bimetallic layers was studied at different relative metal coverages and sample temperatures. STM data indicated clearly that the deposition of Au on the Mo-covered stoichiometric TiO 2 (1 1 0) surface results in an enhanced dispersion of gold at 300 K. The mean size of the Au nanoparticles formed at 300 K on the Mo-covered TiO 2 (1 1 0) was significantly less than on the Mo-free titania surface (2 ± 0.5 nm and 4 ± 1 nm, respectively). Interestingly, the deposition of Mo at 300 K onto the stoichiometric TiO 2 (1 1 0) surface covered by Au nanoparticles of 3-4 nm (0.5 ML) also resulted in an increased dispersity of gold. The driving force for the enhanced wetting at 300 K is that the Au-Mo bond energy is larger than the Au-Au bond energy in 3D gold particles formed on stoichiometric titania. In contrast, 2D gold nanoparticles produced on ion-sputtered titania were not disrupted in the presence of Mo at 300 K, indicating a considerable kinetic hindrance for breaking of the strong Au-TiO x bond. The annealing of the coadsorbed layer formed on a strongly reduced surface to 740 K did not cause a decrease in the wetting of titania surface by gold. The preserved dispersion of Au at higher temperatures is attributed to the presence of the oxygen-deficient sites of titania, which were retained through the reaction of molybdenum with the substrate. Our results suggest that using a Mo-load to titania, Au nanoparticles can be produced with high dispersion and high thermal stability, which offers the fabrication of an effective Au catalyst.

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“…73 Encapsulation of Rh is well-documented on TiO 2 (110) above 700 K, as shown by XPS, LEIS and STM. 74,75 Partial covering by ceria was observed recently on the Rh-CeO 2 / MgO system by using the DRIFTS method. 71 Very recently, near ambient pressure X-ray photoelectron spectroscopy (nap-XPS) demonstrated that the strong metal support interaction effect (SMSI) found in the Ni-ceria system is associated with the decoration and burial of metallic particles by the partially reduced support.…”

Section: X-ray Photoelectron Spectroscopymentioning

confidence: 99%

Probing the interaction of Rh, Co and bimetallic Rh–Co nanoparticles with the CeO₂ support: catalytic materials for alternative energy generation

Varga

Pusztai

Óvári³

et al. 2015

Phys. Chem. Chem. Phys.

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The interaction of CeO 2 -supported Rh, Co and bimetallic Rh-Co nanoparticles, which are active catalysts in hydrogen production via steam reforming of ethanol, a process related to renewable energy generation, was studied by X-ray diffraction (XRD), high resolution electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS) and low energy ion scattering (LEIS). Furthermore, diffuse reflectance infrared spectroscopy (DRIFTS) of adsorbed CO as a probe molecule was used to characterize the morphology of metal particles. At small loadings (0.1%), Rh is in a much dispersed state on ceria, while at higher contents (1-5%), Rh forms 2-8 nm particles. Between 473-673 K pronounced oxygen transfer from ceria to Rh is observed and at 773 K significant agglomeration of Rh occurs. On reduced ceria, XPS indicates a possible electron transfer from Rh to ceria. The formation of smaller ceria crystallites upon loading with Co was concluded from XRD and HRTEM; for 10% Co, the CeO 2 particle size decreased from 27.6 to 10.7 nm. A strong dissolution of Co into ceria and a certain extent of encapsulation by ceria were deduced by XRD, XPS and LEIS. In the bimetallic system, the presence of Rh enhances the reduction of cobalt and ceria.During thermal treatments, reoxidation of Co occurs, and Rh agglomeration as well as oxygen migration from ceria to Rh are hindered in the presence of cobalt.

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Growth of Rh nanoclusters on TiO2(1 1 0): XPS and LEIS studies

Cited by 69 publications

References 28 publications

Atomic scale characterization and surface chemistry of metal modified titanate nanotubes and nanowires

Atomic scale characterization and surface chemistry of metal modified titanate nanotubes and nanowires

Enhanced dispersion and stability of gold nanoparticles on stoichiometric and reduced TiO2(1 1 0) surface in the presence of molybdenum

Probing the interaction of Rh, Co and bimetallic Rh–Co nanoparticles with the CeO₂ support: catalytic materials for alternative energy generation

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Growth of Rh nanoclusters on TiO2(1 1 0): XPS and LEIS studies

Cited by 69 publications

References 28 publications

Atomic scale characterization and surface chemistry of metal modified titanate nanotubes and nanowires

Atomic scale characterization and surface chemistry of metal modified titanate nanotubes and nanowires

Enhanced dispersion and stability of gold nanoparticles on stoichiometric and reduced TiO2(1 1 0) surface in the presence of molybdenum

Probing the interaction of Rh, Co and bimetallic Rh–Co nanoparticles with the CeO2 support: catalytic materials for alternative energy generation

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Product

Resources

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Probing the interaction of Rh, Co and bimetallic Rh–Co nanoparticles with the CeO₂ support: catalytic materials for alternative energy generation