scholarly journals Gas-Phase Photodegradation of Decane and Methanol onTiO2: Dynamic Surface Chemistry Characterized by Diffuse Reflectance FTIR

2008 ◽  
Vol 2008 ◽  
pp. 1-9 ◽  
Author(s):  
William Balcerski ◽  
Su Young Ryu ◽  
Michael R. Hoffmann
Keyword(s):  
Fourier Transform ◽  
Gas Phase ◽  
Diffuse Reflectance ◽  
Organic Molecules ◽  
Free Electrons ◽  
Dynamic Surface ◽  
Oxidation Of Methanol ◽  
Hole Scavenger ◽  
Reflectance Ftir ◽  
Diffuse Reflectance Infrared

Diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) was used to study illuminatedTiO2surfaces under both vacuum conditions, and in the presence of organic molecules (decane and methanol). In the presence of hole scavengers, electrons are trapped at Ti(III)–OH sites, and free electrons are generated. These free electrons are seen to decay by exposure either to oxygen or to heat; in the case of heating, reinjection of holes into the lattice by loss of sorbed hole scavenger leads to a decrease in Ti(III)–OH centers. Decane adsorption experiments lend support to the theory that removal of surficial hydrocarbon contaminants is responsible for superhydrophilicTiO2surfaces. Oxidation of decane led to a mixture of surface-bound organics, while oxidation of methanol leads to the formation of surface-bound formic acid.

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.

Responses of Azospirillum brasilense to Nitrogen Deficiency and to Wheat Lectin: A Diffuse Reflectance Infrared Fourier Transform (DRIFT) Spectroscopic Study

2008 ◽  
Vol 56 (4) ◽  
pp. 615-624 ◽  
Author(s):  
Alexander A. Kamnev ◽  
Julia N. Sadovnikova ◽  
Petros A. Tarantilis ◽  
Moschos G. Polissiou ◽  
Lyudmila P. Antonyuk
Keyword(s):  
Fourier Transform ◽  
Spectroscopic Study ◽  
Azospirillum Brasilense ◽  
Diffuse Reflectance ◽  
Nitrogen Deficiency ◽  
Diffuse Reflectance Infrared
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