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Li[Ni0.5Co0.2Mn0.3]O2 coated with LiFePO4 was synthesized by a co-precipitation method. It consisted of the parent Li[Ni0.5Co0.2Mn0.3]O2 as the core and the LiFePO4 as the coating material, with an average particle diameter of 500 nm. The LiFePO4-coated Li[Ni0.5Co0.2Mn0.3]O2 showed no large initial capacity drop in the first cycle, which generally occurred with cathode materials bearing inactive coating layers such as Al2O3, ZnO, and MgO. Furthermore, it presented a remarkably improved cycle retention rate of over 89% until 400 cycles at 50 °C. We suggest that the LiFePO4 coating technique is a very effective tool to improve the cycle performance of Li[Ni0.5Co0.2Mn0.3]O2 at high temperatures.

In accordance with thermodynamic analysis, cuprous oxide layers are formed spontaneously in the Cu|Cu(II), gluconic acid system at pH > 3.7 under open-circuit conditions. A current peak of Cu2O reduction is observed on cathodic voltammograms at ca −0.7 V, its height being dependent on the exposure time. The analysis of the charge transferred in this region yields the rate of Cu2O formation equal to 1.25 × 10−10 mol cm−2 s−1. The light perturbation of Cu electrode under open-circuit conditions results in the generation of a negative photopotential, which is indicative of n-type conductivity. The threshold wavelength is equal to ∼590 nm and is consistent with a band gap of ∼2.1 eV. Anodic photocurrents, which are observed near the open-circuit potential, decrease with cathodic polarization and change their sign at ∼0.05 V. Analysis of impedance data was performed, invoking the equivalent circuit that accounts for the two-step charge transfer. In the presence of Cu2O, some retardation of Cu(II) reduction was found to occur with a slight increase in the admittance of the double layer. The suggestion has been made that oxide layers formed in Cu(II) gluconate solutions cannot be compact and uniformly distributed over the entire electrode surface. Relevant investigations of surface morphology support this conclusion.

In the last twenty years, direct electro-reduction of solid oxides in molten salt has been investigated extensively. Compared with thermodynamics, kinetics of this solid-to-solid reaction is far less concerned. In this work, Butler-Volmer model was adapted for cyclic voltammetric study of this reaction. Film electrode with three kinds of geometry was proposed to obtain kinetic parameters from the current-overpotential equations. AgCl reduction in 0.5 M KCl–0.5 M NaNO3 was chosen as a model system. The main predictions of planar electrode and cylindrical electrode (inward) were well demonstrated by the electrodes constructed in this work, and the characteristics of cylindrical electrode (outward) were revealed by experimental results from literature. With the obtained relations, kinetics of AgCl/Ag reaction was carefully examined. By in-situ formation of UO2 film on a planar surface in LiCl-KCl-UO2Cl2, the charge transfer coefficient and exchange current density for UO2/U reaction were obtained as 0.19 and 20 mA cm−2, respectively. With the model, electron transfer in an irreversible solid state reaction can now be quantitatively described.

Hydrogen electrosorption was performed in thin electrodeposits of Pd alloys with Pt, Au, and Rh. The possibility of their application as phase charging–discharging systems was investigated. The values of specific pseudocapacitance, power, and energy were calculated for hydrogen-saturated Pd-rich electrodes for temperatures 283–313 K. The best working parameters are exhibited by Pd–Rh alloys with 85–95% Pd, and by Pd–Pt alloys with 90–95% Pd in the bulk. The maximum values of specific pseudocapacitance are ca. 4,500 F g−1, specific energy ca. 150 J g−1 and specific power up to 750 W g−1 (per the mass of the electroactive material). In the case of the alloy deposits on reticulated vitreous carbon, their characteristics related to the total mass of the electroactive material and the substrate are comparable with those for other supercapacitors utilizing various redox reactions.

In the current work, the effect of aniline concentration on the polymerization process and supercapacitive behavior of graphene oxide/multiwalled carbon nanotubes/polyaniline (GMP) nanocomposites were studied. Based on the obtained results, GMP nanocomposite with 0.5 M aniline (GMP5) was selected as the optimum concentration in terms of high current density and high specific capacitance. Nafion-based ionic polymer-free metal composite (IPFMC) supercapacitor was fabricated for the GMP5 nanocomposite. Solid-state symmetric supercapacitor was made after spraying of GMP5 in. on both sides of Nafion membrane. The electrochemical properties were investigated by cyclic voltammetry (CV), galvanostatic charge–discharge (CD), and electrochemical impedance spectroscopy (EIS) techniques in 0.5 M Na2SO4.The specific capacitance of 383.25 F g−1 (326 mF cm−2) and 527.5 F g−1 (42 mF cm−2) was obtained for the GMP5 in solid-state supercapacitor and three-electrode cell at a scan rate of 10 mV s−1, respectively. The maximum energy and power densities of 53.64 and 1777.4 W kg−1 were obtained for the IPFMC-based supercapacitor.

In this work, a series of VO2(B) samples were synthesized via a hydrothermal process by reducing V2O5 with different concentrations of oxalic acid. The prepared samples were characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscopy, cyclic voltammetry, and galvanostatic charge–discharge. Furthermore, the microdefects of VO2 samples were characterized by positron lifetime spectroscopy. The results revealed that VO2(B) was successfully prepared and the concentration of reducing agent had a certain influence on the microstructures and properties. The electrochemical performance measurements showed that all samples had good cycle stability in 2 mol/L KOH solution. The x = 1.50 sample displayed higher discharge capacitance of 149.5 F g−1 at 30 mA g−1 and the discharge capacitance remained about 67% even after 80 charge/discharge cycles. The positron lifetime spectra revealed that the main defects in VO2 samples were microvoids, and the defect concentration and size were affected by the C2H2O4 concentration.

Voltammetry of microparticles, an electrochemical methodology based on the record of the voltammetric response of sparingly soluble solids mechanically transferred to the surface of inert electrodes in contact with suitable electrolytes, is able to provide significant analytical information in the fields of conservation and restoration of cultural goods. Using this methodology, identification, speciation, and relative and absolute quantification of analytes from works of art samples can be achieved. Applications to the analysis of organic and inorganic pigments in paints, fibbers, ceramic materials as well as alteration compounds in paintings and metallic artifacts are reviewed.

The discrete Chebyshev algorithm for nonparametric estimation of autocorrelation function of electrochemical random time series is presented. The algorithm is resistant to a trend of electrochemical noise. The discrete Chebyshev algorithm is tested using the model electrochemical noise corresponding to the equilibrium two-element Voigt circuit. The algorithm is used for nonparametric estimation of autocorrelation function of corrosion noise and electronic noise of measuring instrument.

Electrochemical sensors for the detection of specific biomolecules have attracted a lot of interest over the recent years due to their high sensitivity, selectivity, simple preparation and quick response. This article summarizes the recent progress related to the application of nanomaterials in electrochemical detection of glucose and insulin. We give an overview of electrode concepts based on nanomaterials for electrochemical non-enzymatic glucose detection and non-immune insulin detection and review the electrochemical performances and limitations of these sensors. The mechanisms of the electrocatalytic oxidation of glucose on different nanomaterial-based metallic electrodes are compared. Attention is also focused on schemes of insulin detection on selected nanoparticle-modified carbon electrodes. Finally, the review outlines perspectives of future developments in electrochemical detection of both biomolecules.