Search results for "X-ray photoelectron spectroscopy"
showing 10 items of 416 documents
Oxygen defects: The key parameter controlling the activity and selectivity of mesoporous copper-doped ceria for the total oxidation of naphthalene
2012
Mesoporous CeO2 modified by the addition of copper has shown high efficiency for the total oxidation of naphthalene. High activity and 100% selectivity to carbon dioxide throughout the whole range of temperatures studied were achieved for copper loadings of 3.6% and lower. The catalytic behaviour has been related to the concentration of surface oxygen defects. A clear correlation between the concentration of surface oxygen defects (determined by XPS and DRIFTS) and the catalytic performance has been identified. Catalytic activity increased as copper was incorporated into the ceria up to 3.6%. In this range of copper content the copper was incorporated into the cubic fluorite lattice of CeO2…
Liquid phase exfoliation of antimonene: systematic optimization, characterization and electrocatalytic properties
2019
Antimonene, a novel group 15 two-dimensional material, is attracting great attention due to its outstanding physical and chemical properties. Despite its thermodynamic stability, the pronounced covalent character of the interlayer interactions imposes severe limitations on its exfoliation into mono- and few-layer. Here, we develop a systematic study of liquid phase exfoliation (LPE) with the aim to optimize antimonene production in terms of concentration and dimensional anisotropy, investigating the most relevant experimental factors affecting the exfoliation: pre-processing of pristine antimony, solvent selection based on Hansen solubility parameters and ultrasound conditions. Moreover, ex…
Nano-composite thermochromic thin films and their application in Energy-efficient glazing
2010
A hybrid atmospheric pressure and aerosol-assisted chemical vapour deposition strategy is presented as a facile route for the production of vanadium dioxide nano-composite thin films. The effect of the inclusion of gold nanoparticles and the use of a surfactant molecule, tetraoctylammonium bromide, is discussed. The films were fully characterised using a wide variety of techniques, including scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy and UV/vis/NIR spectroscopy. It is shown that micro-structural changes brought about by careful control of film growth conditions, and/or the use of surfactant, lead to an enhancement of thermochromic properties. Gold nano…
Impact of Ir modification on the durability of FeNC catalysts under start-up and shutdown cycle conditions
2022
A common problem associated with FeNC catalysts is their poor stability dominated by the carbon oxidation reaction (COR). In this work, the feasibility of stabilizing FeNC catalysts with small quantities of Ir was explored. With iridium being present, instead of COR the oxygen evolution reaction should be favored. The impact on structure and morphology was investigated by 57Fe Mössbauer spectroscopy, X-ray photoelectron spectroscopy, Raman spectroscopy and transmission electron microscopy. The catalytic activity and durability for the oxygen reduction reaction was evaluated by rotating ring disc electrode experiments and accelerated stress tests mimicking the start-up and shutdown cycle (SS…
Synthesis and characterization of carbon coated sponge-like tin oxide (SnOx) films and their application as electrode materials in lithium-ion batter…
2016
Nanoporous metal oxides are widely used for the development of various functional nanostructures. We report on the synthesis of sponge-like tin oxide films on copper foil by anodization of electrochemically deposited tin films. The thin films are functionalized using a surface-anchoring carbon precursor-polymer (poly(acrylonitrile-b-dopamine acrylamide)) followed by annealing at elevated temperature to convert the polymer coating into a carbonaceous coating. The as prepared and the carbon coated films are characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and Raman spectroscopy. Subsequently, both SnOx films are employed as a…
MOCVD growth of TiO2 thin films on single crystal GaAs substrates
2000
Abstract TiO 2 thin films have been grown on (100)GaAs and (111)GaAs substrates by low-pressure metal organic chemical vapour deposition (LP-MOCVD). Titanium(IV) isopropoxide, Ti{OCH(CH 3 ) 2 } 4 , was used as a precursor and TiO 2 films were obtained without an additional oxygen flux. Scanning electron microscopy (SEM) experiments have shown a well ordered rod-like crystallisation in the films grown on (100)GaAs. This ordered crystallisation was favoured by a high deposition temperature ( T d =700°C). By contrast, no distinct order was observed in the films grown on (111)GaAs substrates. X-ray diffraction patterns revealed a mainly rutile structure for the TiO 2 films deposited on (100)GaA…
Corrosion behaviour of heavily deformed pearlitic and brass-coated pearlitic steels in sodium chloride solutions
2014
Abstract The influence of plastic deformation and galvanic coupling on the microstructure and corrosion behaviour of pearlitic steel and brass-coated pearlitic steel was investigated in sodium chloride solution at 25 °C. Microstructural changes were quantified using scanning electron microscopy coupled with EBSD. Chemical and electrochemical modifications were evaluated using XPS, ZRA, the electrochemical microcell technique and the weight loss method. From these experiments, the influence of microstructural changes on the electrochemical parameters and the corrosion rate was discussed.
Magnetic and optical properties in degenerated transition metal and Ga co-substituted ZnO nanocrystals
2019
Abstract In order to study the influence of itinerant electrons on magnetic properties of transition metal substituted ZnO nanocrystals, nanopowders containing different amounts of Ga and fixed amounts of Fe, Ni and Mn ions were synthesized. The ions of different transition metals and Ga were successfully introduced into the ZnO structure using solvothermal synthesis method. X-ray diffraction, scanning electron microscopy, hard X-ray photoelectron spectroscopy and Rietveld refinement were used to characterize the synthesized nanocrystals. Optical measurements revealed that Ga substitution can change the light transmittance/absorption in the infrared part of the electromagnetic light spectru…
Chemical characterization of gallium droplets grown by LP-MOCVD.
2006
International audience; This study is concerned with the chemical characterization of metallic gallium droplets, obtained on silicon (1 0 0) substrates with a single growth step, by the LP-MOCVD technique with TMGa like precursor. These structures are characterized by SIMS, XPS and TEM. The analyses results lead to a structure proposition for the droplets. The core is composed of metastable metallic gallium with a non-negligible carbon quantity probably coming from incomplete precursor decomposition. The outer part, composed of gallium oxide maintains the structure stability. Covering of the substrate by a thin gallium layer of gallium compounds is observed.
Changes of lead silicate glasses induced by leaching
1998
Abstract The structural differences in the surface region between freshly fractured and leached silicate glasses containing 16.7, 18.8 and 44.4 mol% PbO, respectively, were investigated by photoelectron spectroscopy (XPS). The optical properties and the thicknesses of leached layers were determined by reflection measurements. The binding energies of the O1s signal components for untreated samples can be ascribed to non-bridging (NBO) and bridging (BO) oxygen and oxygen associated with lead as network former (OPb). The binding energy of OPb was found to be 529.1 ± 0.2 eV. For quantitative conclusions, relative XPS sensitivity factors were determined for oxygen, silicon and lead in these glas…