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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]

Electrochemical synthesis, in situ spectroelectrochemistry of conducting polyindole (PIn), polyindole-TiO 2 (PIn-TiO 2 ) and polyindole-ZnO (PIn-ZnO) nanocomposites were investigated. The PIn and polymer nanocomposites were tested electrochemically for rechargeable batteries. The films were characterized by means of CVs, in situ UV-visible, FT-IR spectroscopies, in situ resistivity measurements, energy dispersive X-ray (EDX), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The charge-discharging behavior of a Zn/1 M ZnSO 4 /PIn cell with a capacity of around 90 Ah Kg −1 and on open circuit potential of around 1.45 V was compared with Zn/1 M ZnSO 4 /PIn-nanocomposite. The potential differences of redox couples (ΔE) for nanocomposites films show very good reversibility. A positive shift of potential was observed for polymer nanocomposites during redox scan. A significant variability was observed for in situ conductivity of the PIn and polymer nanocomposites. During in situ UV-visible and FT-IR measurements, intermediate spectroscopic behavior and positive shifts of wavelengths were observed for PIn and polymer nanocomposites. The SEM, TEM and EDX of nanocomposite films show the presence of nano particle in PIn. [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: 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 cost. This paper presents a method for the construction of graphene paste electrode (GPE) from reduced graphene oxide (RGO). Direct electrochemical detection of drug is of high importance in analytical chemistry. Here, the GPE was successfully used for the determination of acetazolamide (ACZ). So, the influence of some experimental variables such as working solution pH, supporting electrolyte, scan rate, pulse amplitude, and possible interferences were studied. The proposed sensor exhibited a high sensitivity and good selectivity, and it was applied for clinical evaluation of ACZ. [Copyright &y& Elsevier]

Abstract: A carbon paste electrode modified with cobalt nanoparticles (CoNPs) was prepared and used for low level chlorpromazine (CPZ) determination in biological samples. The measurement was made using differential pulse voltammetry. The influence of some experimental variables such as carbon paste composition, working solution pH, supporting electrolyte, scan rate, pulse amplitude and possible interferences were studied. The modified carbon paste electrode exhibited a linear current response over the concentration range between 0.002 and 1.0μMCPZ, with a detection limit of 0.6nM. The proposed sensor exhibited a high sensitivity, good selectivity and was successfully applied for clinical evaluation of CPZ. [Copyright &y& Elsevier]

Abstract: A carbon paste electrode modified with gold nanoparticle was prepared and used for low level acetazolamide (ACZ) determination in aqueous media. The measurement was made using differential pulse voltammetry. The influence of some experimental variables such as carbon paste composition, working solution pH, supporting electrolyte, scan rate, pulse amplitude and possible interferences were studied. The prepared and characterized modified carbon paste electrode demonstrated a linear current response over the concentration range between 0.01μM and 80.0μM ACZ, with a detection limit of 7.1nM. The proposed sensor exhibited a high sensitivity and good selectivity and was applied for clinical evaluation of ACZ. [Copyright &y& Elsevier]

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]

Two novel conducting polyindole (PIn) based on γ‐Fe2O3 and γ‐Al2O3 nanocomposites with LiClO4 on Au electrode (Au/PIn/ ClO4−@γ‐Al2O3 and Au/PIn/ ClO4−@γ‐Fe2O3) as cathode materials for lithium‐ion rechargeable batteries were fabricated via an in situ electropolymerization approach. The PIn and polymer nanocomposites were characterized by FT‐IR, SEM, TEM, EDX, and TGA. The electrochemical properties of PIn and polymer nanocomposites were studied by cyclic voltammetry (CV), in situ conductivity measurements, electrochemical impedance spectroscopy and charge–discharging test. The optical properties of the samples were also investigated by in situ UV‐Visible spectroscopy. The CV results show better reversibility for polymer nanocomposites in compered PIn. The intermolecular interaction between nanoparticles and PIn were confirmed by FT‐IR. The TEM images of polymer nanocomposites show that γ‐Fe2O3 and γ‐Al2O3 are embedded in PIn matrix. The thermal stability of the polymer nanocomposites has increased compared to that of PIn. The in situ conductivity of polymer nanocomposites were increased at about 0.20 order of magnitudes in compared to PIn. The electrochemical properties and charge–discharging behavior of the materials were measured with Li/LiClO4+ACN/Au‐PIn, Li/LiClO4+ACN/Au‐PIn‐γ‐Al2O3, and Li/LiClO4+ACN/Au‐PIn‐γ‐Fe2O3 cells using a constant current of 0.5 mA/cm2. The results for polymer nanocomposites cells indicated better discharging characteristics at about 116–124 mAh/g with very good cyclic properties in compered to PIn cell. The discharge capacities achieve the best value after 30–40 cycles with around drops 3–6% after 20,000 times. POLYM. COMPOS., 40:496–505, 2019. © 2017 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

The inhibition effect of a Schiff base with several functional groups on the corrosion of aluminum in alkaline solution is studied by experimental techniques and density function theory (DFT) calculations. The Schiff base are characterized by 1 HNMR, 13 CNMR, FT-IR, and CHN elemental analysis. In addition, different electrochemical and corrosion techniques such as weight loss, tafel polarization, electrochemical impedance spectroscopy (EIS) and optical microscopy images are performed to analyze the inhibiting performances. In the Tafel measurements the cathodic Tafel slopes values incurred small changes with increasing the inhibitor concentration, which revealed that the inhibitor was adsorbed on the aluminum surface. The inhibition efficiencies are calculated from weight loss measurement and electrochemical tests. The adsorption of the inhibitor onto the aluminum surface follows the Langmuir adsorption isotherm with the free adsorption energy of −8.66 kJ mol −1 . The calculated adsorption energies and the amount of charge transfer obtained by DFT calculation revealed that corrosion inhibition effectively occurs with chemisorption, where new N Al bonds are formed between of N atoms in azo (–N N–) group and Al surface atoms, which is confirmed from ab initio molecular dynamics (AIMD) simulation. [ABSTRACT FROM AUTHOR]

In this work, we presented a novel conducting poly ( p -nitroaniline-co- N -methylaniline) (P( p -NAn-co-NMAn)) material, obtained by electrocopolymerization of para -nitro aniline ( p -NAn) and N -methyl aniline (NMAn) in aqueous sulfuric acid solution. The purposes of this research are investigation and characterization properties of synthesized copolymers and investigation of catalytic effect of NMAn on the polymerization of para-nitro aniline. Electrosynthesis was carried out using cyclic voltammetry technique with different monomer feed concentrations. Characterization of samples were carried out by cyclic voltammetry, in situ conductivity measurements, scanning electron microscopy (SEM), in situ UV–vis, and FT-IR spectroscopy techniques. The cyclic voltammograms of P( p -NAn), P(NMAn) and P( p -NAn-co-NMAn) showed that the peak potentials were located at different values due to different monomer concentration employed during the electrosynthesis process. The in situ conductivity of the p -NAn-co-NMAn increased with increasing the [ p -NAn]/[NMAn] concentration ratios. Mechanisms of polymerization and copolymerization reactions of homo and copolymers were suggested. The in situ UV–vis. spectroscopy results revealed strong absorption bands at different applied potentials and a spectroscopic behavior of copolymers intermediate between that of the homopolymers. The FT-IR spectroscopy and SEM analysis results showed the fundamental differences between the structures and morphology of the homo- and copolymers. [ABSTRACT FROM AUTHOR]

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]

The glucose-capped CdSe quantum dots (QDs) and 1-ethyl-3-methyl-imidazolium:PF 6 (EtMIMPF 6 ) ionic liquid (IL) have been incorporated in the graphite paste electrode (GPE) and used for the voltammetric determination of minoxidil. The high permeability of IL as a hydrophilic binder to polar species, in addition to improving the faradaic current, resulted in increased capacitive current. In order to further improvement of the faradaic signal, we employed a glucose-capped CdSe QDs. Cyclic voltammetry and Faradaic impedance spectroscopy (FIS) indicated that incorporating the QDs into the composite matrix although was not able to significantly improve the kinetics of minoxidil oxidation, but remarkably enhanced the magnitude of the anodic peak current. The sluggish expansion of diffusion layer in viscose IL medium and the microdisc-geometry like behaviour of nanoparticles provided a proper condition for transition from the planar semi-infinite diffusion to the thin layer behaviour. Density functional theory (DFT) was found to yield a good description of the enhancement of signal in the presence of nanomaterials. The results of calculation support that the change in diffusion manner, and not improving in the electron transfer capability at electrode/electrolyte interface, is responsible for the observed signal enhancement. A detailed mechanism for oxidation of minoxidil was also proposed. [ABSTRACT FROM AUTHOR]