Structural changes of Au–Cu bimetallic catalysts in CO oxidation: In situ XRD, EPR, XANES, and FT-IR characterizations

Polyaniline-modified natural fibers have been recognized as promising candidates for conductive clothes, UV protection, and electromagnetic interference shielding. Hence, the purpose of this study was to investigate the effect of surface deposition of cotton fibers using polyaniline via in situ polymerization, and preceding structural changes were further screened by FT-IR, UV-Vis, TGA, SEM/EDX, and conductivity in comparison with bare cotton fibers used as the control sample. Polyaniline was introduced on the surface of cotton fibers as a conductive form, which was confirmed by electrical conductivity (1.54 × 10−4 Scm−1) equivalent to semiconductor materials. Detection of particular peaks at NKα 0.379 keV and ClKα 2.621 keV from EDX analysis revealed the introduction of nitrogen and chlorine, respectively. Polyaniline deposition on the cotton surface was successful to introduce hydrophobic environment to the system to enhance resistance to water absorption meaningfully.

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Effect of Soil Solution pH during the Tetracycline Intercalation on the Structural Properties of a Dioctahedral Smectite: Microstructural Analysis

Journal of Nanomaterials ◽

10.1155/2019/7414039 ◽

2019 ◽

Vol 2019 ◽

pp. 1-17

Author(s):

Walid Oueslati

Keyword(s):

Soil Solution ◽

Structural Changes ◽

Ph Value ◽

Microstructural Analysis ◽

Xrd Analysis ◽

Deformation Bands ◽

Solution Ph ◽

Hydration Properties ◽

In Situ Xrd

The aim of this work is to quantitatively characterize the structural response to a chemical disruption of saturated montmorillonite crystallites by organic molecules (tetracycline (TC)), derived from pharmaceutical waste. The chemical disturbance is performed by varying the surrounding soil solution pH. To show the effect of this chemical perturbation on the interlamellar space (IS) configuration and the hydration properties, an “in situ” XRD analysis, based on the modeling of the 00l reflections, is carried out. The “in situ” XRD analysis is performed by varying the relative humidity conditions (%RH). FTIR SEM and BET- (Brunauer-Emmett-Teller-) BJH (Barrett-Joyner-Halenda) analyses are used as complementary techniques to confirm the structural changes accompanying the intercalation process. Results showed a dependence between solution acid character and the TC adsorption mechanism. From pH values close to 7, the deprotonation of the TC molecule within IS is accelerated by an increasing %RH rate. IR spectroscopy shows that the structure is preserved versus pH value and only a shift of the water deformation bands ascribed to interlamellar water molecule abundance and TC conformation is observed. The surface morphology studied by SEM shows the increase in the surface porosity by increasing the pH value. BET-specific surface area and BJH pore size distribution (PSD) analyses confirm the SEM observations.

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In-Situ X-Ray Characterization of LiMn2O4: A Comparison of Structural and Electrochemical Behavior

MRS Proceedings ◽

10.1557/proc-496-275 ◽

1997 ◽

Vol 496 ◽

Cited By ~ 3

Author(s):

Mark A. Rodriguez ◽

David Ingersoll ◽

Daniel H. Doughty

Keyword(s):

Crystal Structure ◽

Structural Changes ◽

Phase Changes ◽

X Ray ◽

In Situ Xrd ◽

Electrochemical Cycling ◽

Kinetic Effects ◽

Carbon Anodes

ABSTRACTLixMn2O4 materials are of considerable interest in battery research and development. The crystal structure of this material can significantly affect the electrochemical performance. The ability to monitor the changes of the crystal structure during use, that is during electrochemical cycling, would prove useful to verify these types of structural changes. We report in-situ XRD measurements of LiMn2O4 cathodes with the use of an electrochemical cell designed for in-situ X-ray analysis. Cells prepared using this cell design allow investigation of the changes in the LiMn2O4 structure during charge and discharge. We describe the variation in lattice parameters along the voltage plateaus and consider the structural changes in terms of the electrochemical results on each cell. Kinetic effects of LiMn2O4 phase changes are also addressed. Applications of the in-situ cell to other compounds such as LiCoO2 cathodes and carbon anodes are presented as well.

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