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Issue 4, 2018
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Dye-sensitized electron transfer from TiO2 to oxidized triphenylamines that follows first-order kinetics

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Abstract

Two sensitizers, [Ru(bpy)2(dcb)]2+ (RuC) and [Ru(bpy)2(dpb)]2+ (RuP), where bpy is 2,2′-bipyridine, dcb is 4,4′-dicarboxylic acid-2,2′-bipyridine and dpb is 4,4′-diphosphonic acid-2,2′-bipyridine, were anchored to mesoporous TiO2 thin films and utilized to sensitize the reaction of TiO2 electrons with oxidized triphenylamines, TiO2(e) + TPA+ → TiO2 + TPA, to visible light in CH3CN electrolytes. A family of four symmetrically substituted triphenylamines (TPAs) with formal Eo(TPA+/0) reduction potentials that spanned a 0.5 eV range was investigated. Surprisingly, the reaction followed first-order kinetics for two TPAs that provided the largest thermodynamic driving force. Such first-order reactivity indicates a strong Coulombic interaction between TPA+ and TiO2 that enables the injected electron to tunnel back in one concerted step. The kinetics for the other TPA derivatives were non-exponential and were modelled with the Kohlrausch–William–Watts (KWW) function. A Perrin-like reaction sphere model is proposed to rationalize the kinetic data. The activation energies were the same for all of the TPAs, within experimental error. The average rate constants were found to increase with the thermodynamic driving force, consistent with electron transfer in the Marcus normal region.

Graphical abstract: Dye-sensitized electron transfer from TiO2 to oxidized triphenylamines that follows first-order kinetics

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Article information


Submitted
01 Sep 2017
Accepted
16 Nov 2017
First published
17 Nov 2017

This article is Open Access
All publication charges for this article have been paid for by the Royal Society of Chemistry

Chem. Sci., 2018,9, 940-949
Article type
Edge Article

Dye-sensitized electron transfer from TiO2 to oxidized triphenylamines that follows first-order kinetics

B. N. DiMarco, L. Troian-Gautier, R. N. Sampaio and G. J. Meyer, Chem. Sci., 2018, 9, 940
DOI: 10.1039/C7SC03839A

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    [Original citation] - Published by The Royal Society of Chemistry (RSC) on behalf of the Centre National de la Recherche Scientifique (CNRS) and the RSC.
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    [Original citation] - Published by the PCCP Owner Societies.
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    [Original citation] - Published by The Royal Society of Chemistry (RSC) on behalf of the European Society for Photobiology, the European Photochemistry Association, and RSC.
  • For reproduction of material from all other RSC journals:
    [Original citation] - Published by The Royal Society of Chemistry.

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