scholarly journals Changes of Pd Oxidation State in Pd/Al2O3 Catalysts Using Modulated Excitation DRIFTS

Catalysts ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 116
Author(s):  
Gian Luca Chiarello ◽  
Ye Lu ◽  
Miren Agote-Arán ◽  
Riccardo Pellegrini ◽  
Davide Ferri
Keyword(s):  
Particle Size ◽  
Fourier Transform ◽  
Infrared Spectroscopy ◽  
Oxidation State ◽  
Diffuse Reflectance ◽  
X Ray ◽  
Spectral Changes ◽  
Diffuse Reflectance Infrared ◽  
X Ray Absorption ◽  
Reversible Reduction

Infrared spectroscopy is typically not used to establish the oxidation state of metal-based catalysts. In this work, we show that the baseline of spectra collected in diffuse reflectance mode of a series of Pd/Al2O3 samples of increasing Pd content varies significantly and reversibly under alternate pulses of CO or H2 and O2. Moreover, these baseline changes are proportional to the Pd content in Pd/Al2O3 samples exhibiting comparable Pd particle size. Similar measurements by X-ray absorption spectroscopy on a different 2 wt.% Pd/Al2O3 confirm that the baseline changes reflect the reversible reduction-oxidation of Pd. Hence, we demonstrate that changes in oxidation state of metal-based catalysts can be determined using diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and that this behavior is part of the spectral changes that are returned by experiments under operando conditions.

In situ spectroscopic investigation of a Pd local structure over Pd/CeO2 and Pd/MnOx–CeO2 during CO oxidation

2017 ◽  
Vol 5 (25) ◽  
pp. 12998-13008 ◽  
Author(s):  
Erdem Sasmaz ◽  
Chao Wang ◽  
Michael J. Lance ◽  
Jochen Lauterbach
Keyword(s):  
Fourier Transform ◽  
Co Oxidation ◽  
Local Structure ◽  
Diffuse Reflectance ◽  
Oxidation Activity ◽  
X Ray ◽  
Low Temperature Co Oxidation ◽  
Diffuse Reflectance Infrared ◽  
X Ray Absorption

In situ X-ray absorption fine structure (XAS) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) experiments were performed to elucidate the effect of the Pd local structure on low temperature CO oxidation activity of Pd/CeO2 and Pd/MnOx–CeO2.

Improved Crystallinity of Zinc Sulfide Nanoparticles in Aqueous Environment

2005 ◽  
Vol 879 ◽  
Author(s):  
Navendu Goswami ◽  
P. Sen
Keyword(s):  
Particle Size ◽  
Fourier Transform ◽  
Infrared Spectroscopy ◽  
Fourier Transform Infrared Spectroscopy ◽  
Zinc Sulfide ◽  
Structural Transformation ◽  
Powder Diffraction ◽  
Aqueous Environment ◽  
X Ray ◽  
Zinc Sulfide Nanoparticles

AbstractZinc sulfide nanoparticles, prepared employing a non-equilibrium route, are investigated for surface related effects. Water has been shown to induce a structural transformation in nanoparticles prepared this way, which is not related to their particle size. Employing Fourier transform infrared spectroscopy and x-ray powder diffraction, we show here the importance of S-H interaction in the buildup to the final ZnS structure of these nanoparticles. These particles hold promise as water sensors.

scholarly journals Novel NiMgOH-rGO-Based Nanostructured Hybrids for Electrochemical Energy Storage Supercapacitor Applications: Effect of Reducing Agents

Crystals ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1144
Author(s):  
Konda Shireesha ◽  
Thida Rakesh Kumar ◽  
Tumarada Rajani ◽  
Chidurala Shilpa Chakra ◽  
Murikinati Mamatha Kumari ◽  
...  
Keyword(s):  
Particle Size ◽  
Cyclic Voltammetry ◽  
Fourier Transform ◽  
Infrared Spectroscopy ◽  
Fourier Transform Infrared Spectroscopy ◽  
X Ray Diffraction ◽  
Visible Spectroscopy ◽  
X Ray ◽  
Particle Size Analyzer ◽  
Uv Visible

This paper describes the synthesis and characterization of NiMgOH-rGO nanocomposites made using a chemical co-precipitation technique with various reducing agents (e.g., NaOH and NH4OH) and reduced graphene oxide at 0.5, 1, and 1.5 percent by weight. UV-visible spectroscopy, Fourier-transform infrared spectroscopy, X-ray diffraction, a particle size analyzer, and cyclic voltammetry were used to characterize the composite materials. The formation of the NiMgOH-rGO nanocomposite with crystallite sizes in the range of 10–40 nm was inferred by X-ray diffraction patterns of materials, which suggested interlayers of Ni(OH)2 and Mg(OH)2. The interactions between the molecules were detected using Fourier-transform infrared spectroscopy, while optical properties were studied using UV-visible spectroscopy. A uniform average particle size distribution in the range of 1–100 nm was confirmed by the particle size analyzer. Using cyclic voltammetry and galvanostatic charge/discharge measurements in a 6 M KOH solution, the electrochemical execution of NiMgOH-rGO nanocomposites was investigated. At a 1 A/g current density, the NiMgOH-rGO nanocomposites prepared with NH4OH as a reducing agent had a higher specific capacitance of 1977 F/g. The electrochemical studies confirmed that combining rGO with NiMgOH increased conductivity.

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