Electrochemical Characterization of a Self-Assembled Polyelectrolyte Film

Silva, T.H.; Barreira, Sérgio V. P.; Moura, Cláudia; Silva, F.

doi:10.4152/pea.200303281

Cited by 9 publications

(11 citation statements)

References 17 publications

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“…If a potential pulse is applied to the generator, a burst of product diffuses to the collector (Figure 2), and the time of maximum collection, t mc , is measured. The diffusion coefficient of a Red/Ox species can then be calculated using Equation 3.…”

Section: = σKtmentioning

confidence: 99%

“…The most common method of determining diffusion coefficients for analytes in bulk solutions or through gels and membranes relies on the rotating disk electrode (RDEs) [1][2][3][4][5][6][7] or the rotating ring disk electrode (RRDE). 8 Accurate values for the area of the electrode, A, the number of electrons transferred, n, the concentration of the molecule, C, and the viscosity of the solution, v, must also be known in order to effectively determine the diffusion coefficient from the slope of a Levich Plot.…”

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confidence: 99%

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Rapid and Direct Determination of Diffusion Coefficients Using Microelectrode Arrays

Moldenhauer

Meier

Paul

2016

J. Electrochem. Soc.

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The sensitivity of amperometric sensors is typically set by the rate diffusion of the analyte to the electrode surface, so determining diffusion coefficients in various electrolyte solutions is of fundamental interest. It has been theoretically shown and verified that diffusion coefficients of electrochemically generated analytes can be determined using electrochemical time of flight (ETOF), a method that uses an electrochemical array in which one electrode generates a Red/Ox species, and measures the analyte diffusion times to collecting electrodes of differing distances from a stationary generator. ETOF has the potential to greatly simplify the determination of diffusion coefficients as the analyte concentration, the electroactive area, the solution viscosity, and the electron transfer kinetics can remain unknown. Here we demonstrate an alternative data treatment for ETOF in which the electrochemical flight time is measured for a series of different Red/Ox species of known diffusion coefficients at a single distance. We show this a valid application of a method that has existed for almost 30 years, by determining diffusion coefficients for ruthenium (II) hexamine, and diffusion coefficients in solutions of increased viscosity. Diffusion coefficients are important because they set the sensitivity of amperometric sensors and they are a fundamental property both in membrane permeability and in electrochemical measurements. The most common method of determining diffusion coefficients for analytes in bulk solutions or through gels and membranes relies on the rotating disk electrode (RDEs) 1-7 or the rotating ring disk electrode (RRDE).8 This method determines the diffusion coefficients, D, from the slope of a Levich plot constructed by measuring limiting currents, I L , as a function of square root of the rotation rate, w, according to the Levich equation (Equation 1).Accurate values for the area of the electrode, A, the number of electrons transferred, n, the concentration of the molecule, C, and the viscosity of the solution, v, must also be known in order to effectively determine the diffusion coefficient from the slope of a Levich Plot. The diffusion coefficients of molecules through bulk solution can also be determined quantitatively by wall-jet chronoamperometry, 9 or qualitatively by comparing the CV's of different compounds because the shape of the CV is related to the diffusion coefficient of the molecule. [10][11][12] The other primary option for determining diffusion coefficients of a molecule through a membrane coated over an electrode is impedance spectroscopy, [13][14][15][16][17][18] where the diffusion of the molecule through a membrane or polymer is related to the impedance of the polymer or membrane to current flow. As such, the diffusion through the polymer is related directly to the resistance of charge transfer (mobility) through the membrane, which is related to its conductivity and directly correlated to the diffusion coefficient by the Nernst-Einstein equation (Equation 2).Conductance, σ, ca...

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Section: = σKtmentioning

confidence: 99%

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confidence: 99%

Rapid and Direct Determination of Diffusion Coefficients Using Microelectrode Arrays

Moldenhauer

Meier

Paul

2016

J. Electrochem. Soc.

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“…When the number of layers increases simultaneously with the thickness of the film the diffusion process transforms from linear to radial and the multilayers could be envisage as an array of microelectrodes. To distinct between these two mentioned models electrochemical techniques, specifically, chronoamperometry and cyclic voltammetry can be used [45,46]. Another frequently used method to study multilayers development on solid surfaces is ellipsometry.…”

Section: Introductionmentioning

confidence: 99%

Polymer multilayer film formation studied by in situ ellipsometry and electrochemistry

Haberska

Ruzgas

2009

Bioelectrochemistry

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Polyelectrolyte multilayer films adsorbed on gold surfaces were studied by combined ellipsometric and electrochemical methods. Multilayers were composed of "synthetic" (poly(4-styrenesulfonic acid) ammonium salt (PSS) and poly(allylamine hydrochloride) (PAH) (PSS/PAH)) and "semi-natural" (carboxymethyl cellulose (CMC) and chitosan (CHI) (CMC/CHI)) polyelectrolytes. It was found that only PSS/PAH Layer-by-Layer (LbL) assembled structures result in dense surface confined films that limit permeability of small molecules, such as ferri-/ferrocyanide. The PSS/PAH assemblies can be envisaged as films with pinholes, through which small molecules diffuse. During the LbL deposition process of these films a number of pinholes quickly decay. A representative pinhole diameter was found to be approximately 20 μm, which determines the diffusion of small molecules through LbL films, and yet remains constant when the film consists of a few LbL assembled polyelectrolyte bilayers. CMC/CHI LbL assemblies at gold electrode surfaces give very low density films, which do not limit the diffusion of ferri-/ferrocyanide between the surface of the electrode and the solution.

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“…Table 2 shows the oxidation and reduction maximum values for all P3DDT ilms. Calculated E g values increase from the irst to the last cycle regardless of the electrolyte since the resistance of the carriers is greater for the additional P3DDT layer after each cycle, thus increasing ilm thickness [30,33]. Table 2 for the energy gap, it can be observed that the ilms with the Et 4 NBF 4 electrolyte require less energy for their formation.…”

Section: Cyclic Voltammetrymentioning

confidence: 93%

“…The concentrations used are 0.100 mol L for Et 4 NBF 4 or LiClO 4 electrolyte. The options for the previous concentrations is based on the literature for poly(3-methylthiophene) and poly(3-octylthiophene) [9,10,[30][31][32]. The ilms grown in the present study are labeled in Table 1.…”

Section: Electrochemical Deposition In Poly(3-alkylthiophenes) Ilmsmentioning

confidence: 99%

Electrochemical Deposition of P3AT Films Used as a Probe of Optical Properties in Polymeric System

Sá¹,

Basílio²,

Santana³

et al. 2017

Modern Technologies for Creating the Thin-Film Systems and Coatings

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Poly(3-alkylthiophene) (P3ATs) have been extensively used in photovoltaic devices such as a p-type organic Semiconductors. However, several electronic properties of P3ATs present energy transfer inter-and intra-chains that have direct consequences on the performance of optoelectronic devices. Traditionally electrochemical techniques, such as cyclic voltammetry, chronoamperometry and chronocoulometry, have been applied to process polymer thin ilms and unconventional spectroscopy techniques are used to characterize the electronic properties. In the present work, we used an innovative technique called ellipsometry emission to investigate the optical properties of P3AT ilms. We propose a new approach to study the electrochemical synthesize and unintentional doping processes of polymeric systems. We showed a strong correlation between the electrochemical synthesis and the optical properties controlling the ilm growth conditions for P3ATs. The results obtained in the present study can be potentially utilized for applications in organic devices, mainly in photovoltaic cells when the ilm deposition and the optical properties control are relevant.

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Electrochemical Characterization of a Self-Assembled Polyelectrolyte Film

Cited by 9 publications

References 17 publications

Rapid and Direct Determination of Diffusion Coefficients Using Microelectrode Arrays

Rapid and Direct Determination of Diffusion Coefficients Using Microelectrode Arrays

Polymer multilayer film formation studied by in situ ellipsometry and electrochemistry

Electrochemical Deposition of P3AT Films Used as a Probe of Optical Properties in Polymeric System

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