Visible light photolysis of hydrogen iodide using sensitized layered metal oxide semiconductors: The role of surface chemical modification in controlling back electron transfer reactions

Geoffrey B. Saupe, Thomas E. Mallouk, Won Kim, Russell H. Schmehl

Research output: Contribution to journalArticle

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Abstract

The internally platinized wide bandgap semiconductor K4Nb6O17 can be sensitized by [(bpy)2Ru(4-(2,2′-bipyrid-4-yl)-phenylphosphonic acid](PF6)2 (1). In aqueous iodide solutions at pH 2, the visible light photolysis of HI, to form H2 and I3-, is catalyzed by 1/K4-xHxNb6O17/Pt. The strong bond between the surface and the phosphonate group of 1 allows one to adsorb other surface species, which decrease the rate of the back electron transfer reaction between conduction band electrons and I3- ions. Methylphosphonic acid and undecylphosphonic acid do not form good surface monolayers on 1/K4-xHxNb6O17 and do not increase the rate of hydrogen evolution. Anionic surface modifiers [TiNbO5]nn-, derived from exfoliation of KTiNbO5, and poly(styrenesulfonate), PSS, increase the initial hydrogen evolution rate by factors of 3 and 5, respectively. In the latter case, the initial quantum yield for HI photolysis is ca. 3%. Transient diffuse reflectance spectroscopy was used to monitor the formation and disappearance of I3- ions with 1/K4-xHxNb6O17 and PSS/ 1/K4-xHxNb6O17. The rate constant for the back electron transfer reaction between conduction band electrons and I3- ions decreases from 3.17 (±0.03) × 107 to 3.01(±0.02) × 106 M-1 s-1 upon adsorption of PSS.

Original languageEnglish (US)
Pages (from-to)2508-2513
Number of pages6
JournalJournal of Physical Chemistry B
Volume101
Issue number14
StatePublished - Apr 3 1997

Fingerprint

Photolysis
Chemical modification
metal oxide semiconductors
iodides
photolysis
electron transfer
Metals
Hydrogen
Electrons
hydrogen
Ions
Conduction bands
acids
Acids
conduction bands
Organophosphonates
ions
Iodides
Quantum yield
Monolayers

All Science Journal Classification (ASJC) codes

  • Surfaces, Coatings and Films
  • Physical and Theoretical Chemistry
  • Materials Chemistry

Cite this

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title = "Visible light photolysis of hydrogen iodide using sensitized layered metal oxide semiconductors: The role of surface chemical modification in controlling back electron transfer reactions",
abstract = "The internally platinized wide bandgap semiconductor K4Nb6O17 can be sensitized by [(bpy)2Ru(4-(2,2′-bipyrid-4-yl)-phenylphosphonic acid](PF6)2 (1). In aqueous iodide solutions at pH 2, the visible light photolysis of HI, to form H2 and I3-, is catalyzed by 1/K4-xHxNb6O17/Pt. The strong bond between the surface and the phosphonate group of 1 allows one to adsorb other surface species, which decrease the rate of the back electron transfer reaction between conduction band electrons and I3- ions. Methylphosphonic acid and undecylphosphonic acid do not form good surface monolayers on 1/K4-xHxNb6O17 and do not increase the rate of hydrogen evolution. Anionic surface modifiers [TiNbO5]nn-, derived from exfoliation of KTiNbO5, and poly(styrenesulfonate), PSS, increase the initial hydrogen evolution rate by factors of 3 and 5, respectively. In the latter case, the initial quantum yield for HI photolysis is ca. 3{\%}. Transient diffuse reflectance spectroscopy was used to monitor the formation and disappearance of I3- ions with 1/K4-xHxNb6O17 and PSS/ 1/K4-xHxNb6O17. The rate constant for the back electron transfer reaction between conduction band electrons and I3- ions decreases from 3.17 (±0.03) × 107 to 3.01(±0.02) × 106 M-1 s-1 upon adsorption of PSS.",
author = "Saupe, {Geoffrey B.} and Mallouk, {Thomas E.} and Won Kim and Schmehl, {Russell H.}",
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Visible light photolysis of hydrogen iodide using sensitized layered metal oxide semiconductors : The role of surface chemical modification in controlling back electron transfer reactions. / Saupe, Geoffrey B.; Mallouk, Thomas E.; Kim, Won; Schmehl, Russell H.

In: Journal of Physical Chemistry B, Vol. 101, No. 14, 03.04.1997, p. 2508-2513.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Visible light photolysis of hydrogen iodide using sensitized layered metal oxide semiconductors

T2 - The role of surface chemical modification in controlling back electron transfer reactions

AU - Saupe, Geoffrey B.

AU - Mallouk, Thomas E.

AU - Kim, Won

AU - Schmehl, Russell H.

PY - 1997/4/3

Y1 - 1997/4/3

N2 - The internally platinized wide bandgap semiconductor K4Nb6O17 can be sensitized by [(bpy)2Ru(4-(2,2′-bipyrid-4-yl)-phenylphosphonic acid](PF6)2 (1). In aqueous iodide solutions at pH 2, the visible light photolysis of HI, to form H2 and I3-, is catalyzed by 1/K4-xHxNb6O17/Pt. The strong bond between the surface and the phosphonate group of 1 allows one to adsorb other surface species, which decrease the rate of the back electron transfer reaction between conduction band electrons and I3- ions. Methylphosphonic acid and undecylphosphonic acid do not form good surface monolayers on 1/K4-xHxNb6O17 and do not increase the rate of hydrogen evolution. Anionic surface modifiers [TiNbO5]nn-, derived from exfoliation of KTiNbO5, and poly(styrenesulfonate), PSS, increase the initial hydrogen evolution rate by factors of 3 and 5, respectively. In the latter case, the initial quantum yield for HI photolysis is ca. 3%. Transient diffuse reflectance spectroscopy was used to monitor the formation and disappearance of I3- ions with 1/K4-xHxNb6O17 and PSS/ 1/K4-xHxNb6O17. The rate constant for the back electron transfer reaction between conduction band electrons and I3- ions decreases from 3.17 (±0.03) × 107 to 3.01(±0.02) × 106 M-1 s-1 upon adsorption of PSS.

AB - The internally platinized wide bandgap semiconductor K4Nb6O17 can be sensitized by [(bpy)2Ru(4-(2,2′-bipyrid-4-yl)-phenylphosphonic acid](PF6)2 (1). In aqueous iodide solutions at pH 2, the visible light photolysis of HI, to form H2 and I3-, is catalyzed by 1/K4-xHxNb6O17/Pt. The strong bond between the surface and the phosphonate group of 1 allows one to adsorb other surface species, which decrease the rate of the back electron transfer reaction between conduction band electrons and I3- ions. Methylphosphonic acid and undecylphosphonic acid do not form good surface monolayers on 1/K4-xHxNb6O17 and do not increase the rate of hydrogen evolution. Anionic surface modifiers [TiNbO5]nn-, derived from exfoliation of KTiNbO5, and poly(styrenesulfonate), PSS, increase the initial hydrogen evolution rate by factors of 3 and 5, respectively. In the latter case, the initial quantum yield for HI photolysis is ca. 3%. Transient diffuse reflectance spectroscopy was used to monitor the formation and disappearance of I3- ions with 1/K4-xHxNb6O17 and PSS/ 1/K4-xHxNb6O17. The rate constant for the back electron transfer reaction between conduction band electrons and I3- ions decreases from 3.17 (±0.03) × 107 to 3.01(±0.02) × 106 M-1 s-1 upon adsorption of PSS.

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