Fourier-Transform Infrared and Raman Spectroscopy of Pure and Doped TiO2 Photocatalysts

Österlund, Lars

doi:10.1002/9780470823996.ch8

Cited by 10 publications

(19 citation statements)

References 190 publications

(570 reference statements)

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“…The mechanism for photo-oxidation of organics on TiO 2 has been attributed to either direct hole oxidation [43], or OH radical reaction [44]. If water is required as hole acceptor to generate OH radicals it is vital that not all water is desorbed from the surface, which would results in a decreased reactivity and gradual deactivation of the photocatalyst [13,18]. An interesting implication of this model is that for a given film temperature and relative humidity, and hence a given equilibrium water coverage, it is possible to adjust either the relative humidity or the surface temperature to reach an optimum water coverage, which according to Fig.…”

Section: Water Coverage and Reaction Mechanismmentioning

confidence: 99%

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Spectral Selective Solar Light Enhanced Photocatalysis: TiO2/TiAlN Bilayer Films

et al. 2018

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We demonstrate that spectral selective photocatalytic multilayer films can be tailored such that they can harness the full solar spectrum for enhanced photocatalytic gas-phase oxidation of acetaldehyde. Thin films of anatase TiO 2 were deposited on a thin solar absorber TiAlN film to fabricate bilayer TiO 2 /TiAlN films by dc magnetron sputtering on aluminium substrates. The structural and optical properties of the films were characterized by X-ray diffraction and Raman spectroscopy. The reaction rate and quantum yield for acetaldehyde removal was measured and an almost tenfold enhancement of the quantum yield was observed for the TiO 2 /TiAlN films compared with the single TiO 2 film, on par with enhancements achieved with new heterojunction photocatalysts. The results were interpreted by a temperature-induced change of the reaction kinetics. Absorption of simulated solar light illumination resulted in a temperature increase of the TIAlN film that was estimated to be at most 126 K. We show that a concomitant temperature increase of the top layer TiO 2 by 100 K shifts the water gassurface equilibrium from multilayer to submonolayer coverage. We propose that this is the main reason for the observed enhancement of the photocatalytic activity, whereby gas phase molecules may come in direct contact with free surface sites instead of having to diffuse through a thin water film. The implications of the results for judicious control of temperature and relative humidity for efficient gas-phase photocatalysis and exploitation of selective solar absorbing films are discussed.

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Section: Water Coverage and Reaction Mechanismmentioning

confidence: 99%

“…We have previously shown that the rate determining step in the photocatalytic gas-phase degradation of hydrocarbons on TiO 2 is the oxidation of stable surface-bound intermediates [17,18]. Indeed it is well-known that surface compounds with a carboxylic group (R-CO 2 − ) readily form on metal oxides.…”

Section: Introductionmentioning

confidence: 99%

Spectral Selective Solar Light Enhanced Photocatalysis: TiO2/TiAlN Bilayer Films

et al. 2018

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“…The latter feature can be assigned to These bands overlap with the CH and CH 3 bending and deformation modes in acetaldehyde (Table 1). A peak at 1444 cm -1 is also formed, probably due to formation of acetate [33].…”

Section: In Situ Ftir Spectroscopymentioning

confidence: 99%

“…(15). The major product of this oxidation is formate, which is adsorbed on the TiO 2 surface to form strongly bonded bridging and bidentate species [33]. The formate is then further oxidized to CO 2 and water.…”

mentioning

confidence: 99%

Adsorption and photo-oxidation of acetaldehyde on TiO2 and sulfate-modified TiO2: Studies by in situ FTIR spectroscopy and micro-kinetic modeling

Topalian

Stefanov

Granqvist

et al. 2013

Journal of Catalysis

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Adsorption and photocatalytic oxidation of acetaldehyde have been investigated on TiO 2 and sulphate-modified TiO 2 films (denoted SO 4 -TiO 2 ). In situ Fourier transform infrared spectroscopy was used to study surface reactions as a function of time and number of experimental cycles. Spectral analysis and micro-kinetic modelling show that crotonaldehyde formation occurs spontaneously on TiO 2 but is impeded on SO 4 -TiO 2 , where instead acetaldehyde desorption is significant. Photo-oxidation yields significant amounts of formate on TiO 2 , and was identified as the rate-determining step and associated with site blocking.Significantly smaller amounts of formate were observed on SO 4 -TiO 2 , which is due to the acidity of this surface resulting in weaker bonding of aldehyde and carboxylate intermediate species. Our results are of considerable interest for applications to photocatalytic air purification and to surfaces with controlled wettability.

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“…Consequently, adsorption of formate on TiO 2 have been extensively studied experimentally and theoretically on nanocrystalline [9][10][11][12][13][14] and single crystal [15][16][17][18][19][20][21][22][23][24] TiO 2 . On the rutile TiO 2 (110) surface formate adsorption occurs by deprotonation of formic acid (HCOOH) into one H + and one formate ion HCOOthat binds to O br , and Ti 5c atoms, respectively [15,16,19].…”

Section: Introductionmentioning

confidence: 99%

Co-adsorption of oxygen and formic acid on rutile TiO 2 (110) studied by infrared reflection-absorption spectroscopy

Mattsson

Österlund

2017

Surface Science

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Fourier-Transform Infrared and Raman Spectroscopy of Pure and Doped TiO2 Photocatalysts

Cited by 10 publications

References 190 publications

Spectral Selective Solar Light Enhanced Photocatalysis: TiO2/TiAlN Bilayer Films

Spectral Selective Solar Light Enhanced Photocatalysis: TiO2/TiAlN Bilayer Films

Adsorption and photo-oxidation of acetaldehyde on TiO2 and sulfate-modified TiO2: Studies by in situ FTIR spectroscopy and micro-kinetic modeling

Co-adsorption of oxygen and formic acid on rutile TiO 2 (110) studied by infrared reflection-absorption spectroscopy

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