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Polyaniline/gamma aluminum oxide (PAn/γ-Al 2 O 3 ) nanocomposites were synthesized via in situ electropolymerization on gold electrodes and modified electrodes (Au/PAn/γ-Al 2 O 3 ) were used for the detection of vitamin E (VE). The electrochemical and electropolymerization performance of aniline in the presence of γ-Al 2 O 3 nanoparticles improved dramatically. The kinetic results indicate that the polymerization growth rate of PAn in the presence of nanoparticles catalyst on Au electrode is fast. The resulting electrode exhibited excellent performance with regard to detecting VE. The mechanisms of electropolymerization of aniline in presence of γ-Al 2 O 3 nanoparticle catalyst and mechanism of redox behavior of VE are investigated. The limit of detection (LOD) was observed to be around 0.06 μM. The tolerance limits of some important interfering species with VE were studied. [ABSTRACT FROM AUTHOR]

This study represented a novel conducting poly (p-nitroaniline-co-p-aminophenol) (P(p-NAn-co-p-APh)) material, obtained by electrocopolymerization of para-nitroaniline (p-NAn) and para-aminophenol (p-APh) in aqueous sulfuric acid solution. Copolymerization was carried out using cyclic voltammetry technique on gold electrode with different monomer feed concentrations. The obtained polymer and copolymer films had been characterized by scanning electron microscopy (SEM), in situ conductivity measurements, in situ UV-Vis, and FT-IR spectroscopy. Initial cyclic voltammograms of p-NAn, p-APh and p-NAn + p-APh showed that the peak potentials were located at different values. The in situ conductivity of the copolymers measured between -0.20 V< Esce< 0.70 V increased with decreasing the [p-NAn]/[p-APh] concentration ratio. In situ UV-Vis. spectra of the obtained samples revealed strong absorption bands at different applied potentials and wavelengths. The structure and morphology characterizations of homo and copolymer films were studied by FT-IR spectroscopy and SEM analysis. Fundamental differences between the morphology of the homo- and copolymers were observed. The mechanism of the electrochemical copolymerization reaction was discussed as well. [ABSTRACT FROM AUTHOR]

The present study reports the simultaneous determination of ascorbic acid (AA), dopamine (DA) and uric acid (UA) in phosphate buffer solution (pH 7.0) using graphene paste electrode modified with functionalized graphene sheets (GPE-MFGSs). The presence of FGS inhibited the adsorption of AA owing to the electrostatic repulsion, but was favorable for the affinity adsorption of DA and UA via the ion exchange and hydrogen bonding mechanisms, respectively. This led to the decrease in the oxidation potential of AA and the significantly enhanced oxidation peak currents of DA and UA at the GPE-MFGSs. By cyclic voltammetry and differential pulse voltammetry, the oxidation potentials of AA, DA, and UA, at the GPE-MFGSs in a ternary mixture were found to be well resolved so that their simultaneous determination could be achieved. Furthermore, the influence of some experimental variables such as graphene paste composition, working solution pH, scan rate and pulse amplitude was studied. In addition, by differential pulse voltammetry, the linear dependence of peak current on the concentration was obtained in the ranges of 0.05-9.0, 0.03-13, and 0.03-5.5 µM with the lowest detection limits of 0.02, 0.01, and 0.01 µM for AA, DAand UA, , respectively. [ABSTRACT FROM AUTHOR]

Highlights: [•] Adsorption of medetomidine on graphene was investigated. [•] This study describes powerful method for designating a logical electrochemical mechanism. [•] π-π interactions between the adsorbed molecules and graphene were investigated. [Copyright &y& Elsevier]

This paper presents a method for the construction of a graphene paste electrode (GPE) from reduced graphene oxide (RGO). The GPE was successfully used for the determination of medetomidine. The influence of some experimental variables such as pH, supporting electrolyte, scan rate, and possible interferences were studied. Differential pulse voltammetric (DPV) peak currents of medetomidine increased linearly with its concentration in the range from 0.009 to 2.5 µM. The limit of detection ( LOD) and limit of quantitation ( LOQ) values for the determination of medetomidine were 2.8 and 9.2 nM, respectively. Also, for the first time, the electroreduction behavior of medetomidine was investigated. [ABSTRACT FROM AUTHOR]

Abstract: This work describes a novel type of working electrode for use in voltammetry methods. Graphene is ideally suited for implementation in electrochemical applications due to its reported large electrical conductivity, large surface area, unique heterogeneous electron transfer rate, and low production costs. This paper presents a method for the construction of graphene paste electrode (GPE) from graphene. The GPE is not needed to be modified, because the surface of graphene is functionalized. Direct electrochemical detection of drug is of high importance in analytical chemistry. Here, the GPE was successfully used for the determination of chlorpromazine. [Copyright &y& Elsevier]

We introduce high-performance polyaniline (PANI) nanocomposite supercapacitors based on gamma aluminum oxide (γ-Al 2 O 3 ) and gamma iron (III) oxide (γ-Fe 2 O 3 ) nanoparticles with a high specific surface area. PANI and its polymer nanocomposites are synthesized via in situ electropolymerization on gold electrodes. The structures and morphologies are characterized by cyclic voltammetry, FT-IR spectroscopy, SEM, TEM, and EDX. The electrochemical properties and specific surface area of the electrodes are investigated by galvanostatic charge–discharge, electrochemical impedance spectroscopy (EIS) and BET theory. The enhanced specific capacitance with higher surface area and conductivities is observed in PANI/γ-Fe 2 O 3 (342 F/g), PANI/γ-Al 2 O 3 (292 F/g) and PANI (180 F/g) electrodes with a constant current density of 1A/g. The cyclic performance of the PANI electrodes following 8000 cycles of operations were at 87% (PANI), 91% (PANI/γ-Al 2 O 3 ), and 93% (PANI/γ-Fe 2 O 3 ) of their initial capacitance. In addition, higher specific capacitances, higher conductivity and cyclic self-stabilities observed for the PANI/nanocomposite electrodes can provide new opportunities in the field of energy storage and supercapacitor applications. [ABSTRACT FROM AUTHOR]

Polypyrrole (PPy) and polypyrrole-based gamma aluminum oxide (γ-Al 2 O 3 ) and gamma iron (III) oxide (γ-Fe 2 O 3 ) nanocomposites were synthesized via in situ electropolymerization methods Films were characterized via cyclic voltammetry (CV) and in situ spectroelectrochemistry methods such as in situ UV–Visible spectroscopy and in situ conductivity measurements. Polymer nanocomposite structures and morphologies were studied and characterized via Fourier transform infrared (FT-IR) spectroscopy, electrochemical impedance spectroscopy (EIS), energy dispersive X-ray spectroscopy (EDX), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). According to the CV results of the nanocomposites, the separation of anodic and cathodic peak potential of the redox couples (ΔE) exhibited good reversibility with a positive potential shift compared with PPy during redox sweeps. The electrochemical properties of PPy, PPy/γ-Fe 2 O 3, and PPy/γ-Al 2 O 3 nanocomposite electrodes in a solution of H 2 SO 4 were studied via CV, galvanostatic charge–discharge, and EIS measurements to understand the pseudocapacitance that formed due to oxidation and reduction reactions over the double layer capacitance. Results for the nanocomposites revealed that they were very good candidates for supercapacitor applications, with higher specific capacitances, cyclic self-stabilities, and better rate capabilities than those of PPy films. The specific capacitance values of PPy/γ-Fe 2 O 3 (106 F/g) and PPy/γ-Al 2 O 3 (92 F/g) nanocomposites based on a three-electrode cell configuration from galvanostatic charge–discharge at a constant current density of 1 A/g were higher than that for PPy (75 F/g). [ABSTRACT FROM AUTHOR]