XPS Characterization of a Commercial Cu/ZnO/Al2O3 Catalyst: Effects of Oxidation, Reduction, and the Steam Reformation of Methanol

1988 ◽  
Vol 42 (5) ◽  
pp. 754-760 ◽  
Author(s):  
Brian E. Goodby ◽  
Jeanne E. Pemberton
Keyword(s):  
Photoelectron Spectroscopy ◽  
Surface Region ◽  
Peak Fitting ◽  
Oxidation Reduction ◽  
Xps Characterization ◽  
Fitting Procedures ◽  
Cu Oxidation ◽  
Al2o3 Catalyst ◽  
Oxidative State

X-ray photoelectron spectroscopy (XPS) is used to characterize the surface region of a commercial Cu/ZnO/Al2O3 (33/66/1 wt %) catalyst. A systematic study of the effects of oxidation, reduction, and the steam reformation of methanol on the oxidative state of the Cu component is presented. The Zn XPS features show no changes due to the various treatments. Peak fitting procedures were developed to quantitate the Cu oxidation states on the basis of the XPS Cu 2P3/2 main and satellite features. After oxidation in pure O2 at 300°C, all Cu exists as Cu+2. The Cu/Zn ratio changes from 0.28 to 0.37 as a result of this oxidation, in comparison to the ratio in the catalyst as-received. The reduction studies involved different H2/N2 mixtures (15 to 100% H2) and temperatures (250 to 300°C). The catalyst always contains Cu+1 (7.0 ± 5.0%) and Cu° (93.0 ± 5.0%) sifter reduction. The Cu/Zn ratio decreases from approximately 0.37 in the oxidized catalyst to 0.13 after reduction. After methanol-steam reformation with a 50/50 vol % mixture, the Cu 2P3/2 and Auger features are indicative of complete reduction of all Cu in the catalyst to a reduced Cu° state not seen previously. Changes in the Cu/ Zn ratio of the surface are interpreted in terms of changes in surface morphology of the Cu species.

scholarly journals XPS-Characterization of Heterometallic Coordination Compounds with Optically Active Ligands

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Yenny Ávila-Torres ◽  
Lázaro Huerta ◽  
Noráh Barba-Behrens
Keyword(s):  
Photoelectron Spectroscopy ◽  
Coordination Compounds ◽  
Metal Ion ◽  
Magnetic Behaviour ◽  
Optically Active ◽  
Triangular Array ◽  
Antiferromagnetic Coupling ◽  
Xps Characterization ◽  
Alcohol Derivative

The heterometallic optical complexes [Cu2Co(S,S(+)cpse)3(H2O)3]·4H2O (1) and [Cu2Ni(S,S(+)cpse)3(H2O)3]·10H2O (2) were obtained from the mononuclear copper(II) compound by the addition of nickel(II) or cobalt(II) chlorides, where (H2cpse) is the acetyl amino alcohol derivative N-[2-hydroxy-1(R)-methyl-2(R)-phenylethyl]-N-methylglycine. In comparison with the homotrinuclear copper(II) compound [Cu3(S,S(+)cpse)3(H2O)3]·8H2O reported previously, the substitution of a copper(II) atom by one cobalt(II) ion gave place to a heterotrinuclear compound1, which presents ferromagnetic-antiferromagnetic behaviour. When substituting a copper(II) by a nickel(II) ion, the trinuclear compound2showed an antiferromagnetic coupling. The magnetic behaviour of the heterotrinuclear compounds is driven by the nature of the metal ion which was introduced in the copper(II) triangular array. The ligand and its coordination compounds were characterized by IR, UV-Vis-NIR. Their chemical was confirmed by photoelectron spectroscopy (XPS).

GIAXD and XPS Characterization of sp3C Doped SiC Superhard Nanocomposite Film

2012 ◽  
Vol 512-515 ◽  
pp. 971-974
Author(s):  
Jian Yi ◽  
Xiao Dong He ◽  
Yue Sun ◽  
Zhi Peng Xie ◽  
Wei Jiang Xue ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Physical Vapor Deposition ◽  
Grazing Incidence ◽  
Nanocomposite Films ◽  
Second Phase ◽  
X Ray ◽  
Xps Characterization ◽  
Ss Substrates ◽  
Sic Film

The sp3C doped SiC superhard nanocomposite films had been deposited on stainless steel (SS) substrates at different temperature by electron beam-physical vapor deposition (EB-PVD). The sp3C doped SiC film was studied by grazing incidence X-ray asymmetry diffraction (GIAXD), and X-ray photoelectron spectroscopy (XPS). The results of GIAXD showed that the sp3 doped SiC nanocomposite films were not perfect crystalline, which was composed with fine SiC nanocrystals, and a second phase very similar with diamond like carbon (DLC). XPS analysis showed that the excess C existing in films and turned from diamond into DLC from the surface to inner of film.

Angle Resolved XPS Analysis of Surface Region Defects in Rapid Thermal Annealed Antimony Implanted Silicon

1989 ◽  
Vol 163 ◽  
Author(s):  
S.N. Kumar ◽  
G. Chaussemy ◽  
A. Laugier ◽  
B. Canut ◽  
M. Charbonnier
Keyword(s):  
Photoelectron Spectroscopy ◽  
Oxygen Diffusion ◽  
Surface Region ◽  
Metal Oxide Semiconductor ◽  
Oxide Semiconductor ◽  
High Dose ◽  
Thermal Treatments ◽  
X Ray ◽  
Capacitance Voltage

AbstractAngle-resolved X-ray photoelectron spectroscopy characterization of the surface region of high-dose Sb+ ion implanted silicon, after rapid thermal treatments over various temperatures, is reported. The results obtained are compared with the Rutherford backscattering data and the capacitance-voltage measurements on the metal-oxide-semiconductor mesa structures built on them. Rapid anneal at 1100 °C of the 1.4×1016 Sb+/cm2 samples showed an anomalous deep oxygen diffusion inside the implanted region.

XPS Characterization of Mixed Carbides Obtained from Polymer Precursors

1990 ◽  
Vol 180 ◽  
Author(s):  
Gaetano Granozzi ◽  
Antonella Glisenti ◽  
Gian D. Soraru
Keyword(s):  
Photoelectron Spectroscopy ◽  
Structural Evolution ◽  
Metal Alkoxides ◽  
Pyrolysis Process ◽  
X Ray ◽  
Polymer Precursors ◽  
Xps Characterization

ABSTRACTPolymer precursors for Si-C, Si-Ti-C-O and Si-Al-C-O systems have been obtained from polycarbosilane and the corresponding metal alkoxides. X-ray Photoelectron Spectroscopy (XPS) has been used to follow the structural evolution of these preceramic compounds during the pyrolysis process.

Characterization of Ge1-x-ySixSny Ternary Alloy Surfaces and Ni/Ge1-x-ySixSny Bilayer Reactions by X-Ray Techniques

2015 ◽  
Vol 1770 ◽  
pp. 19-24 ◽  
Author(s):  
Gordon J. Grzybowski ◽  
Arnold Kiefer ◽  
Bruce Claflin
Keyword(s):  
Photoelectron Spectroscopy ◽  
Chemical Shifts ◽  
Surface Oxidation ◽  
Device Fabrication ◽  
Ternary Alloys ◽  
Ambient Conditions ◽  
X Ray ◽  
Wide Range ◽  
Xps Characterization

ABSTRACTInterest in next generation devices that integrate photonic and electronic functionality is focused on extending the capability of existing group IV material systems while maintaining compatibility with existing processing methods and procedures. One such class of materials which has been recently developed, Ge1-x-ySixSny ternary alloys, is being investigated for integrated Si photonics, solar cell materials, telecommunication applications, and for IR photodetectors. These alloys afford the opportunity to decouple the band gap energies and lattice constants over a wide range of values, potentially yielding direct and indirect character that can be coupled with a variety of different substrates dependent on composition.In the present work, we report X-ray photoelectron spectroscopy (XPS) characterization of Ge1-x-ySixSny alloys grown by gas-source molecular beam epitaxy (GS-MBE) and investigate Ni- Ge1-x-ySiySny bilayer reactions with x-ray diffraction (XRD). The surface oxidation of samples stored in ambient conditions were measured with XPS. High resolution spectra showed chemical shifts of Ge, Si and Sn peaks consistent with Ge-O, Si-O and Sn-O bond formation. Depth profiling indicates a homogeneous composition throughout the bulk of the sample with surface oxidation confined to the top few nanometers. A highly tin-enriched layer was indicated at the surface of the material, while silicon was observed to be either enriched or depleted at the surface depending on the sample.To study the interaction of the ternary with an ohmic contact commonly used in device fabrication processes today, nickel layers 30 nm thick were evaporated onto the alloys and were annealed in nitrogen up to 400 °C for periods as long as 1 hour. The XRD data show that the Ni2(Ge1-x-ySixSny) phase forms first followed by Ni(Ge1-x-ySixSny).

π* ← π Shakeup Satellites for the Analysis of Structure and Bonding in Aromatic Polymers by X-Ray Photoelectron Spectroscopy

1986 ◽  
Vol 40 (2) ◽  
pp. 224-232 ◽  
Author(s):  
Joseph A. Gardella ◽  
Susan A. Ferguson ◽  
Roland L. Chin
Keyword(s):  
Quantitative Analysis ◽  
Surface Analysis ◽  
Photoelectron Spectroscopy ◽  
Polymer Surface ◽  
Surface Region ◽  
Initial State ◽  
Final State ◽  
Near Surface ◽  
Peak Fitting ◽  
Pi Orbitals

The applications of ESCA to polymer surface analysis include the use of the secondary final-state effects which lead to satellite structure near the core-level photoemission (PE) lines. Specifically, unsaturated and aromatic functionalities in organic compounds and polymers lead to π* ← π shakeup peaks of less than 10 eV lower kinetic energy (higher binding energy). In the surface analysis of polymers, these features can be utilized for qualitative analysis, identification of the presence and structure of aromatic bonding, and quantitative analysis in determining the amount of a particular block or the aromatic containing function in the near-surface region. Carbon Is shakeups are most often used, but the present study includes detailed qualitative and quantitative analysis of shakeup structures from PE lines from each type of atom in hydrocarbon-, siloxane-, and sulfur-containing polymers. These results show the importance of including the shakeup intensity in quantitative peak area calculations and in peak fitting of complex PE envelopes. These studies prove in a variety of systems that the effects of third-row atoms on the final state lead to the presence of shakeup features in atoms with orbitals which do not participate in the aromatic orbital initial state, thus complicating interpretation of structure from the presence of these features. Results from the siloxane and sulfone polymers indicate that previously held assumptions about the nature of the initial-state molecular orbital may overlook the contribution of empty 3d orbitals or increased charge density on the Si or S atom which would spread the pi orbitals to the oxygen in the aromatic siloxane or sulfone systems. Finally, analysis of these features can provide quantitative analysis of polymeric surface structure by monitoring the relative intensity of the feature to the main PE line.

scholarly journals Hafnium-Doped Mesoporous Silica as Efficient Lewis Acidic Catalyst for Friedel–Crafts Alkylation Reactions

Nanomaterials ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 1128 ◽  
Author(s):  
Huang ◽  
Luo ◽  
Wang
Keyword(s):  
Mesoporous Silica ◽  
Photoelectron Spectroscopy ◽  
Active Sites ◽  
Large Scale ◽  
Solid Catalyst ◽  
Alkylation Reaction ◽  
Reaction Conditions ◽  
Xps Characterization ◽  
Alkylation Reactions

The development of an efficient solid catalyst for Friedel–Crafts (FC) reactions is of great importance to organic synthetic chemistry. Herein, we reported the hafnium-doped mesoporous silica catalyst Hf/SBA-15 and its first use for Friedel–Crafts alkylation reactions. Catalysts with different Si/Hf ratios were prepared and characterized, among which Hf/SBA-15(20) (Si/Hf = 20:1) was the most active catalyst, offering up to 99.1% benzylated product under mild reaction conditions. The influences of reaction conditions on the product were systematically investigated and compared. Pyridine-IR characterization of the catalyst showed that Lewis acid formed the primary active sites for the Friedel–Crafts alkylation reaction. X-ray photoelectron spectroscopy (XPS) characterization revealed that the electron shift from the Hf center to the silica framework resulted in a more active Lewis metal center for FC reactions. Moreover, the catalyst was successfully applied to the alkylation reaction with different alcohols and aromatic compounds. Finally, the Hf/SBA-15(20) catalyst also showed good recyclability in the recycling runs, demonstrating its high potential of being used for large scale FC reactions in the industry.

XPS Characterization of Porphyrin Based Self-Assembled Monolayers on Gold

2012 ◽  
Vol 548 ◽  
pp. 234-238
Author(s):  
Guang Yan Liu ◽  
Wen Cai Wang
Keyword(s):  
Photoelectron Spectroscopy ◽  
Electronic Device ◽  
Internal Standard ◽  
Binding Energies ◽  
Self Assembled Monolayers ◽  
Xps Characterization ◽  
Assembled Monolayers ◽  
Self Assembled ◽  
Cv Measurements

XPS characterization of self-assembled monolayers (SAMs) of tetraphenylporphyrin bearing a rigid tripodal linker by chemisorption of the thiol-derivatized terminal groups on gold substrate is described. The surface structure of the SAMs bearing tripodal linker were analyzed by X-ray photoelectron spectroscopy (XPS), and electrochemical cyclic voltammetry (CV) measurements. XPS confirms the formation of porphyrin SAMs on Au surface and identified bonding configurations of porphyrin molecules in the chemisorption of SAMs. The film thickness values (36 Å) obtained by XPS agree well with the estimated value by assuming the vertical orientation of the molecules on the gold surface. Using the Au4f7/2 as an internal standard, a lower binding energies shift (1.8 eV) of S2p in the SAMs reveals that the porphyrins were chemisorbed onto the surface via sulfurgold bonds. Electrochemical CV measurements suggest near monolayer coverage of the tripodal porphyrins with good stability of the redox SAMs, which have promising application in the development of molecular based electronic device and memory architectures.

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