Russian Journal of Electrochemistry最新文献

The technology for manufacturing electrodes for supercapacitors based on commercial carbon nanotubes with the specific surface area of 109.6 m²/g is optimized aimed at their further application as the carbon electrodes in self-charging supercapacitors. The electrochemical characteristics of electrodes of carbon nanotubes are studied in a symmetrical two-electrode cell using the methods of cyclic voltammetry, galvanostatic charge–discharge, and impedance spectroscopy. The specific capacitance of the electrode in the organic electrolyte consisting of 1-butyl-3-methylimidazolium trifluoromethanesulfonate/propylene carbonate (volume ratio 3 : 1) is shown to be 9.1 F/g.

Dual-atom site catalysts with the adjacent metal atomic sites can cooperatively catalyze oxygen reduction reaction (ORR), showing great potential in ORR field. Herein, the ORR activity and mechanism of a supported metal dual-atom site catalyst M₂-DAC (M is 3d transition metal) is explored thoroughly by density functional theory methods. By calculating E_d of M₂-DAC, all structures are thermodynamically stable and are used for subsequent studies. Considering the adsorption of O₂, total 6 kinds of M₂-DAC are identified as potential candidate materials for catalyzing ORR due to their moderate adsorption of O_2. The binding energy of ORR species and the change of Gibbs free energy in each step of ORR are calculated, and Co₂-DAC exhibits notable catalytic activity (η^ORR = 0.39 V). Moreover, the charge analysis of Co₂-DAC shows that the ORR activity of the catalyst mainly comes from the metal atom and the O atoms coordinated with the metal atoms.

The Gag polyprotein is the major structural protein of the human immunodeficiency virus (HIV). It is responsible for the assembly of new viral particles in the infected cell. This process takes place at the plasma membrane of the cell, and is largely regulated by the interactions of Gag with the lipid matrix of the cell membrane. In this work, we used the inner field compensation method and electrokinetic measurements of the zeta potential in a liposome suspension to study the binding of the non-myristoylated HIV Gag polyprotein to model lipid membranes. To quantify the affinity of the protein for charged and uncharged lipid bilayers, Gag adsorption isotherms were constructed and binding constants were calculated. It was shown that the protein is able to interact with both types of membranes with approximately the same intrinsic binding constants (K_PC = 8 × 10⁶ M^–1 and K_PS = 3 × 10⁶ M^–1). However, the presence of the anionic lipid phosphatidylserine in the lipid bilayer significantly enhances protein adsorption onto the membrane ((K_{{{text{PS}}}}^{{{text{eff}}}}) = 37.2 × 10⁶ M^–1), because phosphatidylserine creates a surface potential jump near the membrane. Thus, the interaction of Gag with membranes is determined more by hydrophobic interactions and the area per lipid molecule, while the presence of a negative surface charge only increases the concentration of the positively charged protein near the membrane.

The electrochemical and electrocatalytic behavior of gold electrodes modified with tetra-4-sulfophthalocyaninates of nickel(II) (NiPc) and copper(II) (CuPc) is studied in aqueous alkaline solutions using cyclic voltammetry. The electrocatalytic activity of phthalocyaninates of these metals in the oxidation of hydroxide ions to form molecular oxygen is assessed and compared with the literature data.

Silver(I) oxide is considered as one of the promising materials for photoelectrochemical technologies because it has an optimal band gap, relatively low cost, and a wide variety of production methods. However, its characteristics such as quantum efficiency, morphology, and crystal structure parameters require optimization, which can be achieved by applying the most suitable method for the obtaining of the material. One of the fairly simple methods is the anodic oxidation of silver or its alloys in alkaline media, which allows obtaining oxide phases with a controlled composition and predictable properties by varying the concentration of the alloy components and electrolysis mode. The purpose of this work is to reveal the features of anodic formation and to determine the photoelectrochemical characteristics of silver(I) oxide on silver–palladium alloys in deaerated 0.1 M KOH solution. The regularities of the anodic formation of Ag(I) oxide on alloys of the Ag–Pd-system with the palladium atomic fraction from 0.05 to 0.20 in deaerated 0.1 M KOH solution were studied by non-stationary electrochemical methods of cyclic voltammetry, chronoamperometry with synchronous recording of photocurrent, and photopotential measurements. The phase composition of the alloys (alpha phase) was determined from the results of X-ray diffractometry. Chemical composition was determined by energy dispersive microanalysis. Photoelectrochemical parameters were calculated from the results of the photocurrent and photopotential measurements. It was established that the Ag(I) oxide anodically formed on silver–palladium alloys is characterized by n-type conductivity and the predominance of donor defects. On the alloys with a relatively low palladium concentration (5 and 10 at %), Ag(I) oxide with a higher concentration of defects is formed, while on alloys with a relatively high palladium concentration (15 and 20 at %), with a lower concentration of defects than on pure silver.

Materials containing cobalt phosphide nanoparticles are among the most promising electrocatalysts for the hydrogen evolution reaction in terms of compromise between activity, cost, and durability. A simple and effective approach to fabricating a nanocomposite of graphene–phosphorene structures decorated with CoP nanoparticles 2–5 nm in size is proposed. The nanocomposite was fabricated by the electrochemical exfoliation of black phosphorus followed by the solvothermal synthesis. The synthesis was carried out in the presence of few-layer graphene structures doped with nitrogen atoms in the solution containing Co²⁺ ions. The electrocatalyst exhibited high activity and stability towards hydrogen evolution reaction in the acidic medium. In order to achieve a current density of 10 mA cm^–2, an overpotential of ~220 mV was required, and the Tafel slope was ~63 mV dec^–1. It is suggested that this result is due to both the synergistic effect of the interaction between graphene and phosphorene structures and the electrocatalytic activity of CoP nanoparticles, which are located at the edges of phosphorene structures.

The ionic mobility and conductivity of composites and compounds of the eutectic and close composition obtained by different methods in the PbF₂–SnF₂ system are studied based on the ¹⁹F NMR and impedance data. The stages of transformation of the ¹⁹F NMR spectra of these samples, their connection with the types of ionic movements, and the possible factors determining their ionic conductivity are considered. It is shown that the composition of the majority of composites includes the fluorite phase characterized by the high values of ionic mobility and conductivity. In the region close to the eutectic, a single-phase sample with the fluorite structure is obtained for the first time. The conductivity of this phase (5 × 10^–3 S/cm at 390 K) makes it possible to consider it as the basis for synthesizing functional materials.

Photosensitive hybrid layers are obtained by electrochemical polymerization of pyrrole and 3,4‑ethylenedioxythiophene in the presence of water-soluble sodium salt of zinc octa(3′,5′-dicarboxyphenoxy)phthalocyaninate containing 16 ionogenic carboxylate groups. The process of the hybrid layer electrodeposition was found to occur most effectively in galvanostatic and potentiostatic modes on the sublayer of poly-3,4-ethylenedioxythiophene–polyacid complex. The electronic and chemical structure and morpho-logy of the hybrid layers of polypyrrole obtained in the presence of zinc octa(3′,5′-dicarboxyphenoxy)phthalocyaninate were studied. Possible reasons are considered why the measured values of photosensitivity and external quantum yield of charge-carrier generation in polypyrrole–zinc octa(3′,5′-dicarboxyphenoxy)phthalocyaninate are several times higher than in poly-3,4-ethylenedioxythiophene–zinc octa(3′,5′-dicarboxyphenoxy)phthalocyaninate.

In this work, the vitamin B₆ detected by using a voltammetric sensor based on the use of MoS₂ nanosheets and ionic liquid-modified carbon paste electrode (MoS₂-IL/CPE). Electrochemical performance in the detection of vitamin B₆ at the MoS₂-IL/CPE was investigated by using cyclic voltammetry (CV), chronoamperometry (CHA), and differential pulse voltammetry (DPV). Compared with the bare CPE, the oxidation peak current of vitamin B₆ at the MoS₂-IL/CPE was significantly increased. A good linear relationship between the oxidation peak current and the vitamin B₆ concentration was found in the range of 5.0–900.0 µM, with a detection limit of 1.5 µM. In addition, MoS₂-IL/CPE was successfully used for determination of vitamin B₆ in the real samples, and was demonstrated to be an effective and sensitive method.

By example of the silicate glasses with the compositions (33.3 – x)Li₂O·xNa₂O·66.7SiO₂ and (33.3 – x)K₂O·xNa₂O·66.7SiO₂ with purely cationic conductivity and chalcogenide glasses (Ag–Cu)_0.33AsSe_1.5 and (Ag–Cu)_0.61AsSe_1.5 with mixed ionic–electronic conductivity, consideration has been given to the describing of the mixed-alkali effect in bimetallic glasses in the framework of a microinhomogeneous-glass-structure model using additive schemes involving concentration dependences of conductivity of monometallic glasses with the monovalent metal content equal to that in the mixed glass. A satisfactory agreement between experimental and calculated data is demonstrated. Herein, in the alkaline silicate glasses the non-linear variation of the conductivity parameters is connected with the migration of two alkaline cations and sequential replacement of the conductivity mainly involving an ion by that involving another ion. In the studied chalcogenide glasses, a similar varying of electrical parameters is connected with the replacement of the majority current carrier upon the equivalent substituting of copper for silver in the glass bulk: the mixed, predominantly ionic conductivity is replaced by purely electronic one.