Charge propagation in [Os(bpy)2(PVP)xCl]Cl polymers. An example of mean field behavior in a system with constrained diffusion of redox sites?

Larsson, Henrik; Sharp, Michael

doi:10.1016/0022-0728(94)03654-l

Cited by 19 publications

(17 citation statements)

References 31 publications

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“…The distance between neighboring redox centers, an important rate-determining parameter in charge propagation, is controlled not only by the total concentration of redox centers but also by their microscopic distribution in fixed-site redox polymers. ,, Various theoretical models of charge transport in redox polymers assume that the redox centers are randomly distributed in the polymeric phases. In reality, this assumption is not always satisfied, and examples of markedly nonrandom distributions of redox sites in polymeric films have been reported. , It is not easy to examine redox center distributions in polymers since no direct methods are available.…”

Section: Resultsmentioning

confidence: 99%

“…Investigations of polymers containing covalently attached redox sites have considered both their fundamental properties, such as charge propagation mechanisms and dependence of charge transport rates on redox site concentrations, − and their applications in amperometric enzyme electrodes, − electrocatalysis, , electrosynthesis, and energy conversion . There is no doubt that an understanding of charge transport mechanisms and rates in redox polymers is essential for optimizing their performance in various applications.…”

Section: Introductionmentioning

confidence: 99%

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Charge Transport in Ferrocene-Containing Polyacrylamide-Based Redox Gels

English

Mikkelsen

1997

J. Phys. Chem. B

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The charge transport properties of the redox gels formed from the copolymerization of vinylferrocene (VF) with acrylamide and N,N‘-methylenebisacrylamide (PVAB gels) are described. The apparent electron diffusion coefficients (D ap) measured by cyclic voltammetry and chronocoulometry exhibit an upward bowlike curvature vs immobilized VF concentration ([VF]imm) within the range 0.1−1.60 mM in 0.10 M supporting electrolyte (NaH2PO4/Na2HPO4, NaClO4, or NaNO3). The range of measured D ap values [(0.6−6.0) × 10-7 cm2 s-1] can be interpreted in terms of the mean-field model developed by Blauch and Savéant (Blauch, D. N.; Savéant, J. M. J. Am. Chem. Soc. 1992, 114, 3323). The large D ap values are attributed to the large λ (range of molecular motion permitted to the ferrocene residues) and large k ex (bimolecular electron self-exchange rate constant of the ferrocenes in the PVAB gels). It was further observed that D ap decreases on increasing the electrolyte (NaClO4 or NaNO3) concentration from 0.10 to 0.50 M, especially at low (0.1−0.6 mM) and high (1.1−1.6 mM) [VF]imm, resulting in almost flat D ap vs [VF]imm profiles at 0.50 M electrolyte. This observation is attributed to increased nonbonded interactions between the polymer matrix, the redox sites, and the electrolyte upon increasing the electrolyte concentration.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Charge Transport in Ferrocene-Containing Polyacrylamide-Based Redox Gels

English

Mikkelsen

1997

J. Phys. Chem. B

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“…(from EIS measurements) [61] and 1.3 10 À10 cm 2 s À1 (lateral diffusion measured by scanning electrochemical microscopy). [62] A value of 6-8 10 À10 cm 2 s À1 has been reported for [Os(bpy) 2 -(PVI) 10 Cl] (PVI: polyvinyl-imidazol) (from CV).…”

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confidence: 99%

Charge Transport in Redox Polyelectrolyte Multilayer Films: The Dramatic Effects of Outmost Layer and Solution Ionic Strength

Tagliazucchi

Calvo

2010

ChemPhysChem

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The redox switching kinetics, that is, charge transfer and transport in layer-by-layer-deposited electroactive polyelectrolyte multilayers is systematically studied with variable-scan-rate cyclic voltammetry. The experiments are performed with films finished in the redox polycation (an osmium pyridine-bipyridine derivatized polyallylamine, PAH-Os) and the polyanion (polyvinyl sulfonate, PVS), in solutions of different electrolyte concentrations. A modified diffusion model is developed to account for the experimentally observed dependence of the average peak potential with the scan rate. This model is able to describe both the redox peak potential and the current, providing information on the electron-transfer rate constants and the diffusion coefficient for the electron-hopping mechanism. While the former does not vary with the ionic strength or the nature of the outmost layer, polyanion-capped films present an electron-hopping diffusion coefficient at low ionic strength that is three orders of magnitude smaller than that for PAH-Os-capped films. The effect is offset at high ionic strength. We discuss the possible causes of the effect and the important consequences for electrochemical devices built by layer-by-layer self-assembly, such as amperometric biosensors or electrochromic devices.

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“…The electrochemical properties of these polymers can be determined by several processes including: (i) electron hopping between the Os centres; (ii) counter-ion transport; and (iii) polymer movement [16][17][18][19][20]. Larson and Sharp concluded from ac-impedance data that the apparent electron diffusion coefficient (D e ) is affected by the Os loading in the film (i.e.…”

Section: Introductionmentioning

confidence: 98%

“…Larson and Sharp concluded from ac-impedance data that the apparent electron diffusion coefficient (D e ) is affected by the Os loading in the film (i.e. by the value of ''x'' in the complex formula) [16]. O'Mullane et al employed scanning electrochemical microscopy to estimate the rates of lateral charge propagation in spin-coated films [21].…”

Section: Introductionmentioning

confidence: 99%