Electrodeposition of polypyrrole for high-performance zinc ion battery

Journal of Solid State Electrochemistry - Zinc-ion batteries are considered as promising energy storage devices for large-scale energy storage due to the simple operation, low cost, and...     

Electrodeposition of polypyrrole on He plasma etched carbon nanotube films for electrodes of flexible all-solid-state supercapacitor

Journal of Solid State Electrochemistry - Flexible and portable supercapacitors have been intensively investigated due to their reliable energy storage performance and promising applications in...     

Conductivity enhancement in raw polypyrrole and polypyrrole nanoparticle dispersions

For certain commercial applications of polypyrrole (PPy), an enhancement of the electrical conductivity of the material is the key to industrial success. In this paper it will be shown that raw PPy with high conductivity (>150 S/cm) can be obtained in very good yield (>90%) by appropriate selection of both bi‐functional additives and reaction conditions which increase the oxidative polymerization rate of pyrrole. The presence of new active centers for the polymerization is demonstrated by UV measurements. In addition, raw PPy synthesized according to the improved method of synthesis shows good stability of the conductivity upon aging at high temperature (150°C) in air. Finally, new PPy dispersions are reported with an average particle size of 67 nm obtained by sonochemical synthesis that can be incorporated into conventional plastic paints for direct metallization of plastics. The conductivity of the new metallization paint developed was 0.4 S/cm with a PPy content of 10 wt%. Copyright © 2006 John Wiley & Sons, Ltd.     

Electrodeposition of uranium and thorium

Cathodic depositions of uranium and thorium were carried out from a number of baths containing the metal salts, and complexing agents. A reducing agent was also present to prevent oxidation of the element. The deposition was also carried out at controlled pH. The current density ranged from 50 to 200 mA cm^–2. The purity of the deposited metals was better than 99.7%. The mechanism of formation of uranium and thorium is proposed and discussed.     

Characterization of the radical cation and the dication species of polypyrrole by spectroelectrochemistry: Kinetics,redox properties,and structural changes upon electrochemical cycling

The reported optical study appraises the formation during the redox process of the polypyrrole (PPy) species starting from the allowed electronic transitions of the polymer. The redox mechanism is described by two monoelectromic transfers: PPPP^·+ + 1e^? (E₁) PP^·+(E₂)An evaluation of the absorbance coefficients of the cationic and dicationic species is provided. Chronoabsortometry allows the electrochemical parameters and kinetics of the processes to be estimated. The stability area of the species is discussed in terms of the electrochemical parameters. Relaxation of the system after different steps of charge transfer is studied. The equilibrium reactions are followed by a change in absorbance of PPy film. It appears that the redox potentials E₁ and E₂ of the couples are very close. For non-cycled polymer, the redox potential E₂ could be higher than E₁. In return, after cycling PPy with all the charge, structural alteration could reverse the order of formation of the species. The changes of the absorption diagram caused by cycling also sugest that the charge appears mainly in the dication form in that case.     

In situ electrochemical solid-phase extraction of anions and cations using polypyrrole and overoxidized sulfonated polypyrrole

A new method for the extraction of both anions and cations is proposed using electro-synthesized polypyrrole (PPy) and overoxidized sulfonated polypyrrole film (OSPPy). In situ anion (chloride, nitrate, sulfate) and cation (calcium, magnesium) uptake and release were examined under controlled potential conditions for prospective applications in electrochemically controlled solid-phase extraction (EC-SPE). The PPy film was used as an anode (anion-exchanger) and OSPPy film was used as a cathode (cation-exchanger) material and reverse order of the electrodes were investigated in EC-SPE. This new cell arrangement containing two ion exchanger polymer electrodes was developed to provide in situ removal of both anions and cations from aqueous solution. Simple preparation of the film coatings on a platinum plate was possible using a constant potential method. Applied positive and negative potentials facilitated the in situ extraction and desorption of ions, respectively. Both anions and cations were desorbed into sample aliquot and were determined by ion chromatography (IC). The method was validated using a standard reference material and tested for the determination of the ions in real water samples.     

Electrochemical measurements of the ion conductivity, permselectivity and transference numbers of polypyrrole and polypyrrole derivatives

Electrochemical dc and ac measurements were carried out on free-standing polypyrrole (ppy) membranes to study the ion conductivity and permselectivity of the polymer as a function of the oxidation state. The membranes were prepared by electropolymerisation and mounted in a two-compartment cell, where the oxidation state of the ppy membrane could be adjusted by potentiostatic polarisation and the ion conductivity and permselectivity of the polymer could be measured in a symmetrical electrolyte/membrane/electrolyte configuration. Combining constant current permeation experiments with solution analysis using ion chromatography (IC) and atomic absorption spectroscopy (AAS), it was demonstrated that ppy exhibits not only an appreciable ion conductivity but also a distinct permeability and selectivity for anions in the oxidised state. Incorporation of immobile anions like dodecylsulfate or copolymerization with a modified pyrrole monomer like N-sulfopropyl-pyrrole carrying a sulfonate group leads to modified membranes which exhibit distinct cation permselectivity in the reduced state. Such a membrane can be switched dynamically between anion and cation permeability through electrochemical oxidation and reduction of the polymer backbone. Received: 27 March 1997 / Accepted: 18 July 1997     

Pyrene-loaded polypyrrole microvessels

The encapsulation of guest molecules within polymeric hollow nano- or microscale structures is a rapidly developing field of interdisciplinary research due to a variety of applications ranging from drug delivery and sensor fabrication to nanoscale synthesis and bioinspired mineralization. We report on the encapsulation of pyrene within three-dimensional polypyrrole microvessels synthesized by precipitation polymerization of pyrrole onto toluene droplets that contain pyrene. Steady state and time-resolved fluorescence measurements show that the optical response and dynamics of encapsulated pyrene is significantly different from that in the free solution, likely due to interactions with oligomeric species generated during the polymerization process that partition into the organic core of the microvessel. Our results indicate that the encapsulation process can have a significant influence on the local environment of encapsulated species, an issue that is critical from the perspective of potential synthetic or medical applications.     

Anion-excluding polypyrrole films

A new method for modifying polypyrrole films is described. It involves complete oxidation of the film. The film produced is electronically non-conductive but ionically conductive, and has ion-selective properties based on the exclusion of anionic species. The effective pH within the film can be controlled by the choice of supporting electrolyte used during the oxidative treatment, without loss of selectivity. Cyclic voltammetry is used to demonstrate the effect of film pH on the rate of dopamine oxidation in a neutral supporting electrolyte.     

Photopolymerized polypyrrole microvessels

We report on the preparation of water-filled polymer microvessels through the photopolymerization of pyrrole in a water/chloroform emulsion. The resulting structures were characterized by complementary spectroscopic and microscopic techniques, including Raman spectroscopy, XPS, SEM, and TEM. The encapsulation of fluorescent, magnetic, and ionic species within the microvessels has been demonstrated. Confocal microscopy and fluorescence anisotropy measurements revealed that the encapsulated chromophore (Rhodamine 6G) resides within voids in the capsules; however, strong interaction of the dye with polypyrrole results in a measurable decrease in its rotational dynamics. Microvessels loaded with ferrofluid exhibit magnetic properties, and their structures can be directed with an external magnetic field. TEM measurements allowed imaging of individual nanoparticles entrapped within the vessels. The application of Cu(2+)-loaded microvessels as a transducer layer in all-solid-state ion-selective electrodes was also demonstrated.     

Electrodeposition of gold nanoclusters on overoxidized polypyrrole film modified glassy carbon electrode and its application for the simultaneous determination of epinephrine and uric acid under coexistence of ascorbic acid

A novel biosensor was fabricated by electrochemical deposition of gold nanoclusters on ultrathin overoxidized polypyrrole (PPyox) film, formed a nano-Au/PPyox composite on glassy carbon electrode (nano-Au/PPyox/GCE). The properties of the nanocomposite have been characterized by field emission scanning electron microscope (FE-SEM), X-ray photoelectron spectroscopy (XPS), powder X-ray diffraction (XRD) and electrochemical investigations. The nano-Au/PPyox/GCE had strongly catalytic activity toward the oxidation of epinephrine (EP), uric acid (UA) and ascorbic acid (AA), and resolved the overlapping voltammetric response of EP, UA and AA into three well-defined peaks with a large anodic peak difference. The catalytic peak currents obtained from differential pulse voltammetry increased linearly with increasing EP and UA concentrations in the range of 3.0 × 10⁻⁷ to 2.1 × 10⁻⁵ M and 5.0 × 10⁻⁸ to 2.8 × 10⁻⁵ M with a detection limit of 3.0 × 10⁻⁸ and 1.2 × 10⁻⁸ M (s/n = 3), respectively. The results showed that the modified electrode can selectively determine EP and UA in the coexistence of a large amount of AA. In addition, the sensor exhibited excellent sensitivity, selectivity and stability. The nano-Au/PPyox/GCE has been applied to determination of EP in epinephrine hydrochloride injection and UA in urine samples with satisfactory results.     

Electrodeposition and Characterization of Polyaniline Film

Polyaniline film was prepared by electrochemical method in an acidic solution of aniline. The micromorphology of the polyaniline film was transformed to three-dimensional network structure instead of little particles while the deposition time was extended. The peak wavelength of the photoluminescence spectrum was 491 nm. The luminous intensity increased with the extension of deposition time, and so did the electrochemical activity.     

Electrodeposition of rhenium and its alloys

The processes of electrodeposition of rhenium and its alloys with nickel from aqueous solutions are considered. The results of theoretical and experimental studies of the process of perrhenate ion reduction are analyzed: the data on the possible mechanisms of the cathodic process, participation of atomic hydrogen in it, potentials of transition of rhenium to different oxidation degrees. Codeposition of rhenium and nickel is discussed. The effect of complexation on the current efficiency of rhenium deposition is considered. Information of the sources of data discussed in this paper is provided.     

Electrodeposition and characterization Zn-Co alloy

The present work details optimization of a stable acid chloride bath for electroplating of bright Zn-Co alloy on mild steel using gelatin and glycine as additives. It was found that the addition of gelatin along with glycine changed the deposition pattern markedly. A suitable bath has been formulated using conventional Hull cell experiments. The bath under plating conditions were found to exhibit anomalous codeposition with preferential deposition of less noble (zinc) over more noble (cobalt) as characterized by Zn-Fe group metal alloys. Investigation revealed that the current density (c.d.), temperature, and pH of the bath have strong effect on the composition of the deposit. Influence of bath constituents and operating parameters on appearance and composition of deposits were studied as measure of their performance against corrosion. A variety of deposits were obtained and their corrosion resistances were measured by Tafel method with/without chrome passivation. Experimental results demonstrated the fact that the corrosion resistances of Zn-Co alloys increased with percent of Co in the deposit except at very high c.d. This is due to the fact at very high c.d. the deposit becomes very porous and thick as evidenced by SEM image. The formation of Zn-Co alloy is confirmed by EDAX analysis. A stable chloride bath for Zn-Co alloy deposition has been proposed and discussed. The formation of passive film on chromatization is indicated by almost same E _corr value of all Zn-Co electroplates irrespective of the current densities at which they have been deposited. Published in Russian in Elektrokhimiya, 2009, Vol. 45, No. 7, pp. 811–816. The text is published in the original.     

Electrodeposition of Film-Forming Macroions

Ionizable film-forming macromolecules (RCOOH, RNH2, etc.) have recently found large-scale application as electrodepositable paints. Using bases or acids as solubilizers, macroanions (RCOO^?) or macrocations (RNH₃ are deposited from aqueous dispersions on the anode or cathode, respectively.

The electric current deposits the paint solids practically free from volatile organics on the outer and inner surfaces of merchandise, resulting in higher corrosion protection at substantially lower cost. Bath droplets adhering to freshly electrocoated objects are rinsed back into the bath by a process involving ultrafiltration. Thus electrocoating is one of the ecologically and commercially most viable paint processes.     

Biosensing and drug delivery by polypyrrole

Conducting polypyrrole is a biological compatible polymer matrix wherein number of drugs and enzymes can be incorporated by way of doping. The polypyrrole, which is obtained as freestanding film by electrochemical polymerization, has gained tremendous recognition as sophisticated electronic measuring device in the field of sensors and drug delivery. In drug delivery the reversing of the potential 100% of the drug can be released and is highly efficient as a biosensor in presence of an enzyme. In this review we discuss the applications of conducting polypyrrole as biosensor for some biomolecules and drug delivery systems.     

Linear arrangements of polypyrrole microcontainers

Linear arranged polypyrrole microcontainers have been assembled into one or two lines on patterned silicon micro-electrodes with line widths of 50 and 200 microm, respectively.     

Narrow pore-diameter polypyrrole nanotubes

Bulk quantities of electrically conducting nanotubes of polypyrrole having narrow pore diameter (6 nm) can be synthesized rapidly by chemical oxidative polymerization of pyrrole in the presence of stoichiometric amounts of V2O5 nanofibers. The V2O5 nanofibers act as templates for polymerization and yield, as the initial product, polypyrrole nanotubes with pores filled with V2O5. The V2O5 dissolves readily in aq. 1.0 M HCl, yielding hollow polypyrrole nanotubes having conductivity of approximately 2 S/cm. As-synthesized polypyrrole nanotubes spontaneously reduce noble metal ions to the corresponding metal nanoparticles at room temperature without any capping or dispersing agents. For example, 3-5 nm size nanoparticles of Ag, Au, and Pd, etc., deposit readily on the surface of the tubes which then migrate spontaneously to the pore, and, in the case of Ag, coalesce in the core, yielding 4-8 nm diameter coaxial cables of Ag surrounded by a 20-30 nm thick polypyrrole fiber sheath.