Interfacial charge transfer in Pt-loaded TiO2 P25 photocatalysts studied by in-situ diffuse reflectance FTIR spectroscopy of adsorbed CO

A. Litke, H. Frei, E.J.M. Hensen, J.P. Hofmann

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Abstract

The efficiency of photocatalytic systems is strongly depending on the charge carrier transfer from the excited semiconductor to co-catalyst particles attached on its surface. In this study, we investigated the influence of photo-induced charge transfer in photoplatinized TiO2 P25 photocatalysts by diffuse reflectance FTIR spectroscopy of CO molecules adsorbed on the Pt co-catalyst under well-defined gas phase conditions. In contrast to aqueous conditions, where shifts of the CO stretching vibration of up to 50 cm−1 have been reported, the observed shifts under gas phase conditions are very small (<1 cm−1). This demonstrates that the difference in dielectric properties between aqueous electrolytes and vacuum are critical for the development of prominent shifts of adsorbed CO bands upon trapping of photogenerated charge carriers on co-catalyst particles. The experimental findings are discussed in terms of an electrostatic Stark effect, charge screening, co-adsorption, coverage-dependent shifts of the vibrational bands of adsorbed CO and photocatalytic surface reactions.
LanguageEnglish
Pages84-88
JournalJournal of Photochemistry and Photobiology A: Chemistry
Volume370
DOIs
StatePublished - 2019

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Carbon Monoxide
Photocatalysts
Charge transfer
Spectroscopy
Charge carriers
Catalysts
Gases
Stark effect
Surface reactions
Dielectric properties
Electrolytes
Stretching
Electrostatics
Screening
Vacuum
Semiconductor materials
Adsorption
Molecules

Cite this

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title = "Interfacial charge transfer in Pt-loaded TiO2 P25 photocatalysts studied by in-situ diffuse reflectance FTIR spectroscopy of adsorbed CO",
abstract = "The efficiency of photocatalytic systems is strongly depending on the charge carrier transfer from the excited semiconductor to co-catalyst particles attached on its surface. In this study, we investigated the influence of photo-induced charge transfer in photoplatinized TiO2 P25 photocatalysts by diffuse reflectance FTIR spectroscopy of CO molecules adsorbed on the Pt co-catalyst under well-defined gas phase conditions. In contrast to aqueous conditions, where shifts of the CO stretching vibration of up to 50 cm−1 have been reported, the observed shifts under gas phase conditions are very small (<1 cm−1). This demonstrates that the difference in dielectric properties between aqueous electrolytes and vacuum are critical for the development of prominent shifts of adsorbed CO bands upon trapping of photogenerated charge carriers on co-catalyst particles. The experimental findings are discussed in terms of an electrostatic Stark effect, charge screening, co-adsorption, coverage-dependent shifts of the vibrational bands of adsorbed CO and photocatalytic surface reactions.",
author = "A. Litke and H. Frei and E.J.M. Hensen and J.P. Hofmann",
year = "2019",
doi = "10.1016/j.jphotochem.2018.10.023",
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pages = "84--88",
journal = "Journal of Photochemistry and Photobiology A: Chemistry",
issn = "1010-6030",
publisher = "Elsevier",

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TY - JOUR

T1 - Interfacial charge transfer in Pt-loaded TiO2 P25 photocatalysts studied by in-situ diffuse reflectance FTIR spectroscopy of adsorbed CO

AU - Litke,A.

AU - Frei,H.

AU - Hensen,E.J.M.

AU - Hofmann,J.P.

PY - 2019

Y1 - 2019

N2 - The efficiency of photocatalytic systems is strongly depending on the charge carrier transfer from the excited semiconductor to co-catalyst particles attached on its surface. In this study, we investigated the influence of photo-induced charge transfer in photoplatinized TiO2 P25 photocatalysts by diffuse reflectance FTIR spectroscopy of CO molecules adsorbed on the Pt co-catalyst under well-defined gas phase conditions. In contrast to aqueous conditions, where shifts of the CO stretching vibration of up to 50 cm−1 have been reported, the observed shifts under gas phase conditions are very small (<1 cm−1). This demonstrates that the difference in dielectric properties between aqueous electrolytes and vacuum are critical for the development of prominent shifts of adsorbed CO bands upon trapping of photogenerated charge carriers on co-catalyst particles. The experimental findings are discussed in terms of an electrostatic Stark effect, charge screening, co-adsorption, coverage-dependent shifts of the vibrational bands of adsorbed CO and photocatalytic surface reactions.

AB - The efficiency of photocatalytic systems is strongly depending on the charge carrier transfer from the excited semiconductor to co-catalyst particles attached on its surface. In this study, we investigated the influence of photo-induced charge transfer in photoplatinized TiO2 P25 photocatalysts by diffuse reflectance FTIR spectroscopy of CO molecules adsorbed on the Pt co-catalyst under well-defined gas phase conditions. In contrast to aqueous conditions, where shifts of the CO stretching vibration of up to 50 cm−1 have been reported, the observed shifts under gas phase conditions are very small (<1 cm−1). This demonstrates that the difference in dielectric properties between aqueous electrolytes and vacuum are critical for the development of prominent shifts of adsorbed CO bands upon trapping of photogenerated charge carriers on co-catalyst particles. The experimental findings are discussed in terms of an electrostatic Stark effect, charge screening, co-adsorption, coverage-dependent shifts of the vibrational bands of adsorbed CO and photocatalytic surface reactions.

U2 - 10.1016/j.jphotochem.2018.10.023

DO - 10.1016/j.jphotochem.2018.10.023

M3 - Article

VL - 370

SP - 84

EP - 88

JO - Journal of Photochemistry and Photobiology A: Chemistry

T2 - Journal of Photochemistry and Photobiology A: Chemistry

JF - Journal of Photochemistry and Photobiology A: Chemistry

SN - 1010-6030

ER -