Optical response of porous titania-silica waveguides to surface charging in electrolyte filled pores

J Sefcik, M Kroslak, M Morbidelli

Research output: Contribution to journalArticle

3 Citations (Scopus)

Abstract

In this work, we present a novel method forin situ investigation of surface charging and ion transport inside nanopores of titania-silica waveguide by means of the optical-waveguide-lightmode spectroscopy. Porous oxide waveguides show a strong optical response when exposed to electrolyte solutions, and this response is consistent with oxide surface charging due to changes in ionic strength and pH of the solution in contact with the waveguide. The optical response to pH or electrolyte concentration change is stabilized within several minutes when the solution ionic strength is sufficiently high (0.1M),while it takes two orders of magnitude longer-to-reach stable optical response at very low ionic strengths (<0.1mM). The relaxation times at the high ionic strength are still by several orders of magnitude slower than expected from bulk diffusion coefficients of electrolytes in water. Our results indicate that diffusion of electrolytes is severely hindered (and more so with decreasing ionic strength) in charged pores inside waveguides.

LanguageEnglish
Pages3508-3515
Number of pages8
JournalHelvetica Chimica Acta
Volume85
Issue number10
DOIs
Publication statusPublished - Oct 2002

Fingerprint

Ionic strength
Silicon Dioxide
Osmolar Concentration
Electrolytes
charging
Waveguides
titanium
Titanium
Silica
electrolytes
silicon dioxide
waveguides
porosity
Oxides
Nanopores
oxides
Ion Transport
Optical waveguides
optical waveguides
Relaxation time

Keywords

  • surface charging
  • ion transfer
  • titania-silica

Cite this

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abstract = "In this work, we present a novel method forin situ investigation of surface charging and ion transport inside nanopores of titania-silica waveguide by means of the optical-waveguide-lightmode spectroscopy. Porous oxide waveguides show a strong optical response when exposed to electrolyte solutions, and this response is consistent with oxide surface charging due to changes in ionic strength and pH of the solution in contact with the waveguide. The optical response to pH or electrolyte concentration change is stabilized within several minutes when the solution ionic strength is sufficiently high (0.1M),while it takes two orders of magnitude longer-to-reach stable optical response at very low ionic strengths (<0.1mM). The relaxation times at the high ionic strength are still by several orders of magnitude slower than expected from bulk diffusion coefficients of electrolytes in water. Our results indicate that diffusion of electrolytes is severely hindered (and more so with decreasing ionic strength) in charged pores inside waveguides.",
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Optical response of porous titania-silica waveguides to surface charging in electrolyte filled pores. / Sefcik, J ; Kroslak, M ; Morbidelli, M .

In: Helvetica Chimica Acta, Vol. 85, No. 10, 10.2002, p. 3508-3515.

Research output: Contribution to journalArticle

TY - JOUR

T1 - Optical response of porous titania-silica waveguides to surface charging in electrolyte filled pores

AU - Sefcik, J

AU - Kroslak, M

AU - Morbidelli, M

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N2 - In this work, we present a novel method forin situ investigation of surface charging and ion transport inside nanopores of titania-silica waveguide by means of the optical-waveguide-lightmode spectroscopy. Porous oxide waveguides show a strong optical response when exposed to electrolyte solutions, and this response is consistent with oxide surface charging due to changes in ionic strength and pH of the solution in contact with the waveguide. The optical response to pH or electrolyte concentration change is stabilized within several minutes when the solution ionic strength is sufficiently high (0.1M),while it takes two orders of magnitude longer-to-reach stable optical response at very low ionic strengths (<0.1mM). The relaxation times at the high ionic strength are still by several orders of magnitude slower than expected from bulk diffusion coefficients of electrolytes in water. Our results indicate that diffusion of electrolytes is severely hindered (and more so with decreasing ionic strength) in charged pores inside waveguides.

AB - In this work, we present a novel method forin situ investigation of surface charging and ion transport inside nanopores of titania-silica waveguide by means of the optical-waveguide-lightmode spectroscopy. Porous oxide waveguides show a strong optical response when exposed to electrolyte solutions, and this response is consistent with oxide surface charging due to changes in ionic strength and pH of the solution in contact with the waveguide. The optical response to pH or electrolyte concentration change is stabilized within several minutes when the solution ionic strength is sufficiently high (0.1M),while it takes two orders of magnitude longer-to-reach stable optical response at very low ionic strengths (<0.1mM). The relaxation times at the high ionic strength are still by several orders of magnitude slower than expected from bulk diffusion coefficients of electrolytes in water. Our results indicate that diffusion of electrolytes is severely hindered (and more so with decreasing ionic strength) in charged pores inside waveguides.

KW - surface charging

KW - ion transfer

KW - titania-silica

U2 - 10.1002/1522-2675(200210)85:10<3508::AID-HLCA3508>3.0.CO;2-M

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