Kinetic and structural studies of oxygen availability of the mixed oxides Pr1–xMxOy (M = Ce, Zr)

1996 ◽  
Vol 11 (8) ◽  
pp. 1960-1971 ◽  
Author(s):  
M. Yu. Sinev ◽  
G. W. Graham ◽  
L. P. Haack ◽  
M. Shelef
Keyword(s):  
Gas Phase ◽  
Mixed Oxide ◽  
Photoelectron Spectroscopy ◽  
Mixed Oxides ◽  
Structural Features ◽  
Redox Processes ◽  
Structural Studies ◽  
X Ray ◽  
Speed Up ◽  
Kinetics Of

One composition of Pr–Ce mixed oxide and a range of compositions of Pr–Zr mixed oxide were prepared by coprecipitation methods and characterized by x-ray powder diffraction, thermogravimetric analysis, and x-ray photoelectron spectroscopy. Based on phases formed, the PrOy—ZrO2 system in an oxygen-containing atmosphere at moderate temperatures (up to 800–1000 °C) is analogous to that of CeO2–ZrO2. Addition of either Ce or Zr to pure Pr oxide affects both the total amount of oxygen that can be reversibly exchanged between oxide and gas phase and the kinetics of the redox processes. Ce dramatically increases the amount (per Pr atom) and lowers the temperature of exchange, Zr slightly decreases the amount and also lowers the temperature of exchange, and both modifiers speed up the rate. These observations are rationalized in terms of bulk and surface structural features of the mixed oxides.

Kinetics of the gas-phase halogenation of a polyethylene surface as studied with x-ray photoelectron spectroscopy

1990 ◽  
Vol 23 (17) ◽  
pp. 3922-3928 ◽  
Author(s):  
James F. Elman ◽  
Louis J. Gerenser ◽  
Kim E. Goppert-Berarducci ◽  
John M. Pochan
Keyword(s):  
Gas Phase ◽  
Photoelectron Spectroscopy ◽  
X Ray ◽  
Kinetics Of ◽  
Polyethylene Surface

scholarly journals The origin of the high electrochemical activity of pseudo-amorphous iridium oxides

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Marine Elmaalouf ◽  
Mateusz Odziomek ◽  
Silvia Duran ◽  
Maxime Gayrard ◽  
Mounib Bahri ◽  
...  
Keyword(s):  
Oxidation State ◽  
Photoelectron Spectroscopy ◽  
Mixed Oxides ◽  
Structural Features ◽  
Electrochemical Activity ◽  
Ex Situ ◽  
Initial Oxidation ◽  
Standard Material ◽  
X Ray ◽  
Iridium Oxides

AbstractCombining high activity and stability, iridium oxide remains the gold standard material for the oxygen evolution reaction in acidic medium for green hydrogen production. The reasons for the higher electroactivity of amorphous iridium oxides compared to their crystalline counterpart is still the matter of an intense debate in the literature and, a comprehensive understanding is needed to optimize its use and allow for the development of water electrolysis. By producing iridium-based mixed oxides using aerosol, we are able to decouple the electronic processes from the structural transformation, i.e. Ir oxidation from IrO2 crystallization, occurring upon calcination. Full characterization using in situ and ex situ X-ray absorption spectroscopy, X-ray photoelectron spectroscopy, X-ray diffraction and transmission electron microscopy allows to unambiguously attribute their high electrochemical activity to structural features and rules out the iridium oxidation state as a critical parameter. This study indicates that short-range ordering, corresponding to sub-2nm crystal size for our samples, drives the activity independently of the initial oxidation state and composition of the calcined iridium oxides.

scholarly journals STRUCTURAL FEATURES OF CHROMIUM CARBID COATINGS OBTAINED BY THE MOCVD METHOD FROM THE COL “BARKHOS”

2021 ◽  
pp. 126-130
Author(s):  
S.A. Krokhmal ◽  
Yu.G. Kazarinov ◽  
T.N. Zueva
Keyword(s):  
Gas Phase ◽  
Photoelectron Spectroscopy ◽  
Organic Liquid ◽  
Structural Features ◽  
Structure And Properties ◽  
X Ray

Investigations of the structure and properties of gas-phase coatings obtained with the use of chromium organic liquid (COL) “Barkhos” have been carried out. The studies were carried out by the methods of nanoindentation, fractography, and X-ray photoelectron spectroscopy. It was found that such coatings have a two-level horizontallayered structure.

GROWTH OF OXIDE LAYER ON GERMANIUM (011) SUBSTRATE UNDER DRY AND WET ATMOSPHERES

1999 ◽  
Vol 06 (06) ◽  
pp. 1053-1060 ◽  
Author(s):  
N. TABET ◽  
J. AL-SADAH ◽  
M. SALIM
Keyword(s):  
Simple Model ◽  
Oxide Film ◽  
Growth Kinetics ◽  
Photoelectron Spectroscopy ◽  
Early Stage ◽  
X Ray ◽  
Apparent Thickness ◽  
Different Temperatures ◽  
Kinetics Of

X-ray Photoelectron Spectroscopy (XPS) has been used to investigate the oxidation of (011) Ge substrates. The sample surfaces were CP4-etched, then annealed in situ, at different temperatures, for various durations. Dry and wet atmospheres were used. The oxidation rate during the early stage was increased by the presence of moisture in the atmosphere. A simple model was used to define and determine an apparent thickness of the oxide film from XPS measurements. The time dependence of the apparent thickness is consistent with a partial coverage of the surface by oxide islands. The growth kinetics of the oxide islands obeys a nearly cubic law.

Gas‐phase x‐ray photoelectron spectroscopy of model molecules relating to the thermochromism in poly(3‐alkylthiophene)

1990 ◽  
Vol 93 (9) ◽  
pp. 6357-6362 ◽  
Author(s):  
M. P. Keane ◽  
S. Svensson ◽  
A. Naves de Brito ◽  
N. Correia ◽  
S. Lunell ◽  
...  
Keyword(s):  
Gas Phase ◽  
Photoelectron Spectroscopy ◽  
X Ray

scholarly journals Effect of Mg/Al molar ratio on the basicity of Mg-Al mixed oxide derived from Mg-Al hydrotalcite

2020 ◽  
Vol 10 (6) ◽  
pp. 625
Author(s):  
Said Arhzaf ◽  
Mohammed Naciri Bennani ◽  
Sadik Abouarnadasse ◽  
Hamid Ziyat ◽  
Omar Qabaqous
Keyword(s):  
Thermal Analysis ◽  
Mixed Oxide ◽  
Mixed Oxides ◽  
Molar Ratio ◽  
Acid Molecule ◽  
X Ray Diffraction ◽  
Phenol Adsorption ◽  
X Ray ◽  
Maximum Quantity ◽  
Uv Visible

<p>The fundamental character of the Mg-Al mixed oxide (Mg<sub>n</sub>(Al)O), derived from the Mg-Al hydrotalcite (Mg<sub>n</sub>Al-CO<sub>3</sub>-HT), where n corresponds to the Mg/Al molar ratio (n: 2, 2.5, 3, 3.5 and 4), was studied by using the adsorption of phenol as a probe acid molecule. The hydrotalcite precursors were prepared by the coprecipitation method. Their derived mixed oxides were obtained by thermal treatment at 450°C in a flow of air. The resulting solids were characterized by X-ray fluorescence spectroscopy (XRF), X-ray diffraction (XRD), infrared spectroscopy (FTIR), thermogravimetric and differential thermal analysis             (TG-DTA), nitrogen physisorption (BET) and phenol chemisorption. The phenol adsorption followed by UV-Visible spectrophotometry shows that the basicity increases with the Mg/Al molar ratio, such that maximum quantity of phenol adsorbed (Q<sub>ads</sub> = 0.54 mmol/g <sub>cat</sub>) was obtained with the mixed oxide derived from the Mg-Al hydrotalcite of Mg/Al molar ratio equal to 3.5.</p>

Structural studies of organoboron compounds. LVI. 1-Benzyl-7-methyl-3,5-diphenyl-2,4,6-trioxa-1-azonia-3-bora-5-boratabicyclo[3.3.0]octane and 1,4,6,9-tetramethyl-2,7-diphenyl-3,8,11,12-tetraoxa-1,6-diazonia-2,7-diboratatricyclo[5.3.1.12,6]dodecane

1992 ◽  
Vol 70 (11) ◽  
pp. 2809-2817 ◽  
Author(s):  
Wolfgang Kliegel ◽  
Gottfried Lubkowitz ◽  
Steven J. Rettig ◽  
James Trotter
Keyword(s):  
Solid State ◽  
Gas Phase ◽  
Phenylboronic Acid ◽  
Direct Methods ◽  
Structural Studies ◽  
Triclinic Space Group ◽  
Full Matrix ◽  
X Ray ◽  
Molar Ratios ◽  
New Type

The preparation of the N-(2-hydroxypropyl)-N-alkylhydroxylamines, 6a (R = CH3) and 6b (R = CH2Ph), and their reactions with phenylboronic acid are described. Regardless of the molar ratios of reactants employed, the reaction with 6b leads to the 1:2 condensate 1-benzyl-7-methyl-3,5-diphenyl-2,4,6-trioxa-1-azonia-3-bora-5-boratabicyclo[3.3.0]octane, 7, while that with 6a gives rise to the 1:1 condensate 1,4,6,9-tetramethyl-2,7-diphenyl-3,8,11,12-tetraoxa-1,6-diazonia-2,7-diboratatricyclo[5.3.1. 12,6]dodecane, 11 (the cyclic BONBON dimer of 4,6-dimethyl-2-phenyl-1,3-dioxa-4-aza-2-boracyclohexane, 9). Compounds 7 and 11 both crystallize in the triclinic space group [Formula: see text]: for 7; a = 13.126(1), b = 15.337(1), c = 10.9469(5) Å, α = 91.727(5), β = 104.647(5), γ = 72.922(7)°, Z = 4; and for 11; a = 9.0807(4), b = 9.1653(3), c = 6.4876(2) Å, α = 97.708(3), β = 108.830(3), γ = 89.188(4)°, Z = 1. The structures were solved by direct methods and were refined by full-matrix least-squares procedures to R = 0.038 and 0.032 for 5879 and 1827 reflections with I ≥ 3σ(F2), respectively. Compound 7 has the expected bicyclic pyroboronate structure, but represents the first reported N-substituted example of this type of compound. Bond lengths involving boron in 7 are (C) O—B(sp3) = 1.428(2) and 1.420(2), (B)O—B(sp3) = 1.472(2) and 1.468(2), N—B(sp3) = 1.737(2) and 1.762(2), C(phenyl)—B(sp3) = 1.588(2) and 1.584(2), (N)O—B(sp2) = 1.402(2) and 1.404(2), (B)O—B(sp2) = 1.331(2) and 1.329(2), C(phenyl)—B(sp2) = 1.555(3) and 1.553(2) Å. The X-ray analysis establishes a centrosymmetric, twofold N → B coordinated, dimeric structure in the solid state for 11 in which each B—O—N segment of a central six-membered BONBON ring is bridged by an O—C—C moiety. Compound 11 represents the first fully characterized example of a new type of "BONBON" compound. Bond distances involving the boron atom are (N)O—B = 1.465(1), (C)O—B = 1.428(1), N—B = 1.695(2), and C(phenyl)—B = 1.607(2) Å. Spectroscopic evidence indicates that in solution and in the gas phase this material exists predominantly as the monomer 9.

scholarly journals Fabrication of Strontium Bismuth Oxides as Novel Battery-Type Electrode Materials for High-Performance Supercapacitors

2018 ◽  
Vol 2018 ◽  
pp. 1-10 ◽  
Author(s):  
Yinghui Han ◽  
Le Li ◽  
Yunpeng Liu ◽  
Xue Li ◽  
Xiaohan Qi ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
High Performance ◽  
Electrode Materials ◽  
Specific Capacity ◽  
Structural Features ◽  
High Electron ◽  
Strontium Content ◽  
X Ray ◽  
Bismuth Oxides ◽  
Improved Performance

A simple and efficient process method for the preparation of strontium bismuth oxides (SBOs) via an impregnation-calcination method is presented. The synthesized active materials are characterized using X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy. The electrochemical performance of the as-synthesized SBO samples is observed to decrease gradually as the strontium content is increased from 25% to 50%. The SBO sample with a Sr/Bi ratio of 1 : 3 shows the highest specific capacitance of 1228.7 F g−1 (specific capacity of 204.8 mAh g−1) at a current density of 1 A g−1 and a good cycling stability (75.1%) over 3000 charge-discharge cycles. The improved performance of the supercapacitors can be attributed to the unique structural features resulting from the addition of appropriate portions of Sr, which supports high electron conductivity and rapid ion/electron transport within the electrode and at the electrode/electrolyte interface. All the results show that the SBOs have considerable potential for use as high-performance battery-type electrodes in supercapacitors.

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