Investigation of Ru(bpy)32+/Nafion® film coated on electrodes studied using in situ spectrocyclic voltammetry and photoluminescence

Lin, Ru Jang; Onikubo, Toshikazu; Nagai, Keiji; Kaneko, Masao

doi:10.1016/0022-0728(93)80131-z

Cited by 63 publications

(32 citation statements)

References 28 publications

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“…33 In the present study the first two factors, which have been previously explored, were maintained constant to focus primarily on the effects of presoaking freshly cast coatings in aqueous media. The first-scan voltammograms in Fig.…”

Section: Discussionmentioning

confidence: 99%

High Sensitivity of Electron Transfer Rates within Nafion Coatings Saturated with Os ( bpy ) 3 2 + to the Extent of Hydration of the Coating

Shi

Anson

1995

J. Electrochem. Soc.

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The sensitivity of the electrochemical responses obtained from electroactive counterions incorporated in Nation coatings to the extent of hydration of the coatings 2748 is shown to be enhanced significantly when the electroactive ion is the only counterion present in the coating. Nation coatings fully saturated with Os(bpy)~ + exhibit unusually narrow and sharply peaked anodic currents in first-scan oxidative voltammograms. This voltammetric feature is accompanied by the expulsion of one-third of the Os complex from the coating. The counterion actually ejected is primarily Os(bpy)] § As the Os(bpy)~ § counterions are ejected, H20 molecules enter the coatings. The quantity of H20 molecules incorporated is so large that the mass of the coating (monitored with a quartz crystal microbalance) increases despite the ejection of the heavy Os(bpy)~ § cations. After several voltammetric cycles, normally shaped voltammograms are obtained that are relatively insensitive to the initial state of hydration of the coatings. The contrasting behaviors of hydrated and unhydrated coatings are compared, and possible explanations are offered for the differences observed.Nation deposited on electrode surfaces is one of the most extensively investigated polyelectrolyte coatings that have been employed to modify the behavior of electrodes. The facile incorporation and retention by Nation coatings of cationic complexes with hydrophobic ligands such as 2,2 '-bipyridine have induced many previous workers to examine the electrochemical responses of electroactive complexes of this type within Nation coatings. Representative early examples can be found in Ref. 1-13. Most previous studies have involved coatings in which only a portion of the initially present, electroinactive counterions (e.g., H § Na § were replaced by electroactive ions, but in one case experiments were conducted with Nation coatings that had been exposed to solutions of Os(bpy)~ § (bpy = 2,2'-bipyridine) for extended periods so that Os(bpy)~ § cations became the only counterions within the coating. 14 Electro-oxidation of these counterions to Os(bpy)~ § required that some of them be ejected from the permselective, polyanionic Nation to maintain electroneutrality within the coating. Such ejection was monitored by means of microprobe electrodes positioned just above the coatings, but only qualitative measurements were possible because of variability in the sensitivity of the microprobe electrodes at Nafion coated electrodes. 14 The present study constitutes an extension and elaboration of this previous work. The use of rotating ring-disk electrodes to monitor the ejection of counterions from Nation coatings allowed quantitative determinations to be obtained. In addition, we observed a high sensitivity of the voltammetric responses obtained from coatings saturated with Os(bpy)~ § to the water content of the coatings. Procedures for varying the extent of hydration during the preparation of coatings were developed to demonstrate the dramatically different types of behavior that c...

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Section: Discussionmentioning

confidence: 99%

High Sensitivity of Electron Transfer Rates within Nafion Coatings Saturated with Os ( bpy ) 3 2 + to the Extent of Hydration of the Coating

Shi

Anson

1995

J. Electrochem. Soc.

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“…Similar electrochemical behavior was also observed when TBA-Nf/TH film was immersed in 0.5 M NaCl instead of 0.5 M H 2 SO 4 . Kaneko and co-workers [33] have demonstrated the influence of water molecules on the electrochemistry of [Ru(bpy) 3 ] 2þ by incorporation into wet Nf and dry Nf films. The wet film exhibits a hydrophilic surface and the ion-exchanged [Ru(bpy) 3 ] 2þ complex is electrochemically active.…”

Section: Resultsmentioning

confidence: 98%

Microenvironment effects on the electrochemical and photoelectrochemical properties of thionine loaded Nafion® films

John

Ramaraj

2004

Journal of Electroanalytical Chemistry

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“…Another reason for the lower electron transfer rate is that the morphology of P(VP-St) is different from that of Nafion. Since the hydrophilic and hydrophobic regions in P(VP-St) are not as obvious as those in Nafion, the redox species are expected to localize in a hydrophobic microenvironment where the mobility of the complexes will be low [50,52]. Instead of the continuous hydrophilic region in Nafion, the hydrophilic clusters in P(VP-St) would be separated, so that the redox species could not migrate freely and rapidly through the whole polymer framework.…”

Section: Discussionmentioning

confidence: 99%

Electron Transfer in the Reduction of Cobalt Porphyrin Incorporated into Nafion and Poly(4-vinylpyridine-co-styrene) Films

Zhao

Zhang

Abe

et al. 1999

J. Porphyrins Phthalocyanines

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Potential step chronoamperospectrometry (PSCAS) measurement was carried out to investigate the one-electron transfer in the reduction of tetraphenylporphyrin cobalt(III) ([ Co III TPP (−2)]+) incorporated into a Nafion or poly(4-vinylpyridine-co-styrene) (P(VP-St)) film coated on an ITO electrode. The electron transfer of the redox centers in the two systems occurred by a physical diffusion mechanism. The fraction of the electroactive complex (R ct ) was independent of the CoTPP concentration in P(VP-St) but decreased with increasing CoTPP concentration in Nafion, especially at high concentrations. In both systems the apparent diffusion coefficient Dapp decreased with increasing CoTPP concentration. The Dapp value in Nafion (1.6 × 10−8 cm 2 s −1 at 0.02 M) was much higher than that in P(VP-St) (1.1 × 10−10 cm 2 s −1 at 0.02 M). The difference in the electron transfer process in the two systems was ascribed to the interaction of the redox center with the polymer framework, the morphology of the polymer matrix, the localization of the redox species in the hydrophilic/hydrophobic region, and the counterion migration under the potential step.

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Investigation of Ru(bpy)32+/Nafion® film coated on electrodes studied using in situ spectrocyclic voltammetry and photoluminescence

Cited by 63 publications

References 28 publications

High Sensitivity of Electron Transfer Rates within Nafion Coatings Saturated with Os ( bpy ) 3 2 + to the Extent of Hydration of the Coating

High Sensitivity of Electron Transfer Rates within Nafion Coatings Saturated with Os ( bpy ) 3 2 + to the Extent of Hydration of the Coating

Microenvironment effects on the electrochemical and photoelectrochemical properties of thionine loaded Nafion® films

Electron Transfer in the Reduction of Cobalt Porphyrin Incorporated into Nafion and Poly(4-vinylpyridine-co-styrene) Films

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