Electrosynthesis Of Polypyrrole Research Articles

Non-enzymatic lactose molecularly imprinted sensor based on disposable graphite paper electrode

Lactose (LAC) is a disaccharide - major sugar, present in milk and dairy products. LAC content is an important indicator of milk quality and abnormalities in food industries, as well as in human and animal health. The present study reports the development of an innovative imprinted voltammetric sensor for sensitive detection of LAC. The sensor was constructed using electropolymerized pyrrole (Py) molecularly imprinted polymer (MIP) on graphite paper electrode (PE). The MIP film was constructed through the electrosynthesis of polypyrrole (PPy) in the presence of LAC (template molecule) on PE (PPy/PE). To optimize the detection conditions, several factors affecting the PPy/PE sensor performance were assessed by multivariate methods (Plackett–Burman design and central composite design). Under optimized conditions, the proposed analytical method was applied for LAC detection in whole and LAC-free milks, where it demonstrated high sensitivity and selectivity, with two dynamic linear ranges of concentration (1.0–10 nmol L−1 and 25–125 nmol L−1) and a detection limit of 0.88 nmol L−1. The MIP sensor showed selective molecular recognition for LAC in the presence of structurally related molecules. The proposed PPy/PE sensor exhibited good stability, as well as excellent reproducibility and repeatability. Based on the results obtained, the PPy/PE is found to be highly promising for sensitive detection of LAC.

Electrosynthesis of polypyrrole nano/micro structures using an electrogenerated oriented polypyrrole nanowire array as framework

The purpose of this paper is to show that it is possible to increase the diameter and length of the nanostructures of a framework formed of oriented polypyrrole nanowires that has been prepared by a templateless electrochemical method based on the use of a pyrrole solution containing a high concentration of weak-acid anion and a low concentration of non-acidic anion. The dimensions of the initial nanowires are increased by performing an additional electrosynthesis in a ‘classical’ monomer solution. Depending on the polarization time of this last synthesis (a few tens of seconds), wires with various diameters, from one hundred up to several hundred nanometers, are obtained. In addition to the variation of the nanowire size, these findings confirm, as outlined in the reaction mechanism we have proposed, that the base of the nanowires is surrounded by a thin non-conductive polymer i.e. by an overoxidized polypyrrole film. Actually this paper shows a proof-of-concept. Indeed one can imagine that the second polymeric electrodeposit could be performed using an organic monomer solution, using functionalized pyrrole monomer to fabricate a biosensor having large specific area, and/or using anions which could be drugs.

Electrodeposition of polypyrrole on Nitinol alloy in the presence of inhibitor ions for corrosion protection

The electrosynthesis of polypyrrole (PPy) films on Nitinol (NiTi) from solutions containing different corrosion inhibitors is reported. The corrosion behaviour of the coated samples was investigated in 0.15M NaCl solution. The presence of molybdate ions in the polymer matrix confers to the substrate a greater resistance to pitting corrosion. The polymer formed potentiostatically in a solution at pH 12 containing nitrate and molybdate is the most efficient in terms of adhesion and corrosion protection. Results are interpreted in terms of the nature of the dopants, the good electroactivity of the polymer and passive properties of the oxide layer.

Conductive hydrogel for bio-electrocatalytic reduction of dioxygen

An enzyme-immobilized electrode represents an important kind of biosensor or bioelectronic device. In this paper, a method of incorporating laccase on an electrode was demonstrated using the electrosynthesis of polypyrrole (pPy) with its redox mediator and alginate as co-dopants. Linear sweep voltammetry showed that the pPy film exhibited biocatalytic activity towards oxygen to water reduction. The catalytic activity and the stability of the film could be controlled by the concentration of alginate used during electrosynthesis. A micropattern of the film revealed its bi-layer structure—where an inner layer of pPy was covered with an outer layer of alginate gel, and demonstrated the geometric control of the film deposition.

Electrosynthesis of Polypyrrole in Low-Viscosity Ionic Liquids

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Electrosynthesis of polypyrrole on steel fiber for solid-phase microextraction of citalopram in serum

A solid-phase microextraction (SPME) technique using steel fiber coated with polypyrrole (PPY) was developed for UV-Vis determination of citalopram in blood serum. The coating was prepared using a three-electrode electrochemical system from an acetonitrile/aqueous (ACN/H(2)O) oxalic acid solution containing 0.01 M of pyrrole monomer by applying a potential range (0-1.3 V) for 25 min. In order to obtain an efficient film of PPY, experimental parameters related to the coating process were optimized, specifically deposition potential, concentration of monomer, and number of cycles. The effects of various parameters on the efficiency of the SPME process such as extraction time, stirring speed, adsorption and desorption temperature, desorption solvent, and pH of desorption solution were also studied. The coating was stable and adhered to the surface of the steel fiber. The method was linear over about three orders of magnitude with an average correlation coefficient of 0.97. Spiking of blank samples with 0.2 μg/mL citalopram afforded a recovery of 84% with a precision of 10.2%. A limit of detection of 0.046 μg/mL (based on S/N = 3) was obtained in the linear dynamic range of 0.046-2.0 μg/mL. The proposed method was applied to monitor citalopram in serum samples.

Electromagnetic reflection, shielding and conductivity of polypyrrole thin film electropolymerized in P-Tulensulfonic acid

The electrosynthesis of polypyrrole (PPy) thin film on stainless steel electrode was performed in P- Tulensulfonic acid. The electromagnetic reflection, shielding effectiveness, permittivity and conductivity in the frequency range 8.2 to 18 GHz were studied. The effect of change in the acid concentration on the properties is reported. The microwave conductivity varies from 16 S/cm to 415 S/cm with frequency. The dielectric constant and dielectric loss factor decreases with increase in frequency.

Electrochemical Synthesis of Polypyrrole in the Presence of Congo Red; Application to Selective Voltammetric Determination of Dopamine in the Presence of Ascorbic Acid

AbstractThe electrosynthesis of polypyrrole (PPy) film has been achieved on glassy carbon electrode (GCE) in aqueous medium of Congo red (CR) by means of cyclic voltammetry (CV). The modified electrode exhibits high electrocatalytic activity toward dopamine (DA) oxidation, with drastic enhancement of the reversibility and peak currents. This modified electrode, due to electrostatic interactions, is capable to mask the response of ascorbic acid (AA) completely and provide an effective method for the detection of minor amounts of dopamine in the presence of high concentrations of AA. The electrochemical response of the film modified electrode is strongly dependent to the switching potential applied in the CV procedure of the electro‐polymerization. The results show that by increasing the switching potential more than 0.75 V, the peak of AA is gradually disappeared. This peak in potential of 0.85 V is reached to capacitive background current. With respect to the destruction of the conjugated structure of ppy and lowering the conductivity of the film at the surface of modified electrode, higher switching potentials cannot be suitable for electropolymerization procedure. The effects of various experimental parameters such as, number of polymerization cycles, switching potential, pH and potential sweep rate on the voltammetric response of dopamine were also investigated. The modified electrode shows a linear response to DA in the range of 0.5 to 100 μM with a detection limit of 0.1 μM. The prepared modified electrode does not show any considerable response toward sulfhydryl compounds, such as, cysteine, penicillamine and glutathione, revealing a good selectivity for voltammetric response to DA. The effective electrocatalytic property, ability for masking the voltammetric responses of the other biological reducing agents together with high reproducibility and stability make the modified electrode suitable for selective and sensitive voltammetric detection of sub‐micromolar amounts of DA in clinical and pharmaceutical preparations.

Two‐step electrosynthesis of polypyrrole for corrosion protection of stainless steel

AbstractSmooth polypyrrole (PPy) films were successfully electrosynthesized on a stainless steel (SS, 1Cr18Ni9) surface by a self‐catalytic two‐step process. SS substrate dissolution during PPy electrosynthesis was effectively depressed. The redox properties and corrosion behavior of PPy film coated SS electrodes were investigated by cyclic voltammetry, electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization. The reduction of PPy was found to include two reaction processes: an anion dedoping process and a cation insertion process. The PPy film was found to lose its electroactivity when polarized at high potentials due to peroxidation. EIS of SS/PPy mainly corresponds to PPy film response and charge transfer resistance decreases as film thickness increases, indicating that SS corrosion can be inhibited effectively by the PPy film.

Electrochemical impedance study of iron electrodes covered by polypyrrole films electrosynthesized in the presence of AOT

The electrosynthesis of polypyrrole (PPy) onto iron electrodes in the presence of sodium bis(2-ethylhexyl) sulfosuccinate (AOT) solutions is characterized by the formation of a gelatinous material in parallel to the growth of the polymer. The electrochemical behaviour of this system under different experimental conditions was investigated using electrochemical impedance spectroscopy (EIS) and cyclic voltammetry. The study was focused in understanding the effects of various parameters, such as nature of the electrolyte and film thickness, on the dissolution process of iron. The response at low frequencies is related with the activity of the substrate. It was found that the electrode impedance for thick films is governed by diffusion of iron ions across the polymer and gel-like layers. Mass transfer contribution is prominent at the early stages of corrosion in chloride solution.

Application of Al2O3 in the electrosynthesis of polypyrrole with fuzzy morphology—Microtentacle

AbstractPolypyrrole (PPy) thin films were electrochemically polymerized onto the electrode surface. In this study alumina was used as the template and PPy film was prepared by electrochemical polymerization using Al/Al2O3 as the working electrode. Surface morphology of PPy was investigated by scanning electron microscopy (SEM) and the results revealed that the application of the template resulted in PPy with fantastic surface morphology which was called microtentacle and the length of the tentacle could reach 15 µm. The morphology can evidently increase the roughness, thus the surface area of the electrode substrate, and provide an intimate contact with the surrounding brain tissue compared to the hard, stiff metal surface. Relationship between PPy morphology and electrochemical polymerization parameters, such as polymerization time, was investigated. The study provided a fundamental method to prepare a PPy‐modified electrode with high surface area. Potential application of the study is proposed. Copyright © 2007 John Wiley & Sons, Ltd.

Conditions to prepare PPy/Al 2O 3/Al used as a solid-state capacitor from aqueous malic solutions

The electrosynthesis of polypyrrole (PPy) has been achieved on aluminium in aqueous medium of malic acid by means of cyclic voltammetry, potentiostatic and galvanostatic techniques. Scanning electron microscopy (SEM) and X-ray microanalysis by dispersion energy spectroscopy (EDS) applying on surfaces show that the PPy coating is developed from the metal surface through the cracks of the initial Al 2O 3 layer. Moreover, the results reveal that the homogeneity of the film achieved increases with the time of electropolymerization. A mechanism involving the participation of the supporting electrolyte and the pyrrole (Py) in distinct active sites was proposed based on the linear sweep voltammetry. It is observed for all the applied electrochemical techniques that the pyrrole concentration has to be higher than 0.1 M to allow the polypyrrole electrodeposition in acid medium. Scanning electron microscopy, secondary electrons (SE) and backscattering electrons (BE), shows that the PPy coating obtained in galvanostatic and potentiostatic modes starts with small islands at weak applied potentials or current densities. The corrosion results in 3% NaCl medium show that the PPy coating decreases the corrosion behaviour of the aluminium. The bilayer Al 2O 3/PPy shows a capacitor with future applications.

Electrodeposition of polypyrrole on aluminium in aqueous tartaric solution

The electrosynthesis of polypyrrole (PPy) has been achieved on aluminium in aqueous medium of tartaric acid by means of cyclic voltammetry, potentiostatic and galvanostatic techniques. Scanning electron microscopy (SEM) and X-ray microanalysis by energy spectroscopy dispersion (EDS) applying on surfaces show that the PPy coating is developed from the metal surface through the cracks of the initial Al 2O 3 layer. A mechanism involving the participation of the supporting electrolyte and the pyrrole (Py) in distinct active sites was proposed based on the linear sweep voltammetry. It is observed for all applied electrochemical techniques that the pyrrole concentration has to be higher than 0.1 M to allow the polypyrrole electrodeposition in acid medium. Scanning electron microscopy, secondary electrons (SE) and backscattering electrons (BE), shows that the PPy coating obtained in galvanostatic and potentiostatic modes starts with small islands at weak applied potentials or current densities. Moreover, EDS reveals a good homogeneity and compactness of the film achieved in galvanostatic method. The corrosion results in 3% NaCl medium show that the PPy coating decreases the corrosion behaviour of the aluminium. The bilayer Al 2O 3/PPy shows a capacitor with future applications.

XPS and RBS characterizations of electrosynthesized polypyrrole films doped with a heteropolyanion, SiMo12O404−

AbstractIn this paper, the electrosynthesis of polypyrrole (PPy) films doped with a Keggin‐type heteropolyanion, SiMo12O404−, is reported. The in situ electrochemical growth of the hybrid film was conducted using an electrochemical quartz crystal microbalance (EQCM) that allowed us to evaluate the doping level of the polymers, which were synthesized in galvanostatic mode. By combining EQCM with chemical analyses, such as X‐ray photoelectron spectroscopy and Rutherford backscattering spectroscopy, it was evidenced that the doping level of the polymer depends on the current imposed during the PPy film synthesis. Copyright © 2006 John Wiley & Sons, Ltd.

Sweet aqueous solution for electrochemical synthesis of polypyrrole: Part 1-A. On non-ferrous metals

The electrosynthesis of polypyrrole (PPy) has been achieved on aluminum electrode in aqueous medium of 0.1 M saccharin sodium salt and 0.5 M pyrrole. Scanning electron microscopy shows that the PPy coating obtained in galvanostatic and potentiostatic modes starts with small islands at weak applied potentials or current densities. Moreover, energy dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) reveal a good homogeneity of the film achieved in cyclic voltammetry during 10 cycles. The electrochemical impedance spectroscopy (EIS) results show that the coating decreases the polarization resistance of the aluminum electrode. The open circuit potential (OCP) and dc polarization measurements achieved in HCl and NaCl solutions displayed a large positive displacement of corrosion potential and a reduction of corrosion current in the case of PPy coating electrode in comparison with electrode bare.

Pyrrole Electropolymerization on Copper and Brass in a Single-Step Process from Aqueous Solution

The electrosynthesis of polypyrrole (PPy) on copper and brass (Cu–Zn alloy) electrodes was performed by anodic oxidation of pyrrole in a sodium tartrate (C4H4Na2O6 0.2 M) aqueous solution. The tartrate counter-ions slow the dissolution of the working electrode by leading to formation of a passivation layer on its surface, and pyrrole electropolymerization takes place. Strongly adherent and homogeneous polypyrrole films were electrodeposited on Cu and Cu–Zn alloy electrodes using different electrochemical techniques, such as potentiodynamic, galvanostatic and potentiostatic modes. The current densities of electropolymerization on brass are generally greater than those observed on copper. The corrosion behaviour of copper-coated electrodes, electrochemically modified by PPy films, was estimated by DC polarization and weight loss at different current densities in 0.1 M HCl solution. The synthesized polypyrrole films were characterised by several microscopic and spectroscopic techniques such as scanning electron microscopy, X-ray photo electron spectroscopy, Fourier transform infrared and Raman analysis. Galvanostatically deposited PPy films are shown to be an alternative to common black-nickel or black-chromium as a decorative top-coating.

Electrosynthesis of polypyrrole in iodide solution. Film growth, redox behaviour and potentiometric response

Electrosynthesis of polypyrrole (PPy) was studied in aqueous lithium iodide solution. The electrochemical polymerization showed features of two-dimensional growth and the reaction was catalyzed by the I 2/I − couple. The potentiometric response of PPy doped with iodide (PPy(I)) was studied both in iodide solutions and solutions containing the redox couple I 2/I − with a fixed concentration ratio 0.4 but varying the initial concentration of iodide in the range 10 −5–1.0 M. Linear, anionic response was observed in the concentration range 10 −1–10 −3 M when only iodide species was present. However, contribution of the redox response to the overall potentiometric response increased with increasing concentration of I 2 although the concentration ration between iodine/iodide was kept constant. The influence of phosphate buffer on the electroactivity of PPy doped with iodide was also studied.

Electrosynthesis of polypyrrole in a nematic liquid crystal

Electrosynthesis of polypyrrole in a nematic liquid crystal

Preparation and properties of polypyrrole/ poly(tetrahydrofuran) composites

Polypyrrole/poly(tetrahydrofuran) composite films were prepared by electrosynthesis of polypyrrole on a platinum electrode precoated with poly(tetrahydrofuran). The conductivities of the films were measured to be 8–15 S/cm at room temperature. The morphology of the films was investigated by scanning electron microscopy and energy-dispersive X-ray spectroscopy. The cyclic voltammogram of the composite film revealed that the composite has electrochemical behavior identical to that of polypyrrole.