Russian Journal of Electrochemistry最新文献

Catalysts of the hydrogen peroxide cathodic synthesis are obtained from multiwalled carbon nanotubes pre-oxidized with nitric acid, follow by hydrogen reduction in the 300–500°C temperature range. Evaluation of physico-chemical properties of the catalysts showed the synthesis method used to be able controlling changes in the surface oxygen groups’ composition without any change in the multiwalled carbon nanotubes’ structure and morphology. Investigation of catalytic activity in the cathodic process for hydrogen peroxide production demonstrated the sample prepared by hydrogen reduction at 300°C with oxygen content of 5.2 at % (according to XPS data) to have the highest efficiency. The sample produced the hydrogen peroxide with the rate of 0.34 mol/(g h) and Faradaic efficiency of 78%. Increase in the reduction temperature above 300°C resulted in a decrease in the rate of Н₂О₂ accumulation without severe changes in Faradaic efficiency.

Phytic acid (PA) benzotriazole composite conversion films with different concentrations of BTA were prepared by an impregnation method, and their wettability, microstructure, and corrosion resistance were studied. The results showed that when the BTA content was 1.6 wt %, the maximum water contact angle of the conversion film reached 137.5°, and the corrosion current density reached a minimum of 1.610 × 10^–7 A/cm². The salt spray and corrosive liquid environments experimental results also showed that the synergistic effect of PA and BTA was the best when the BTA concentration was 1.6 wt %. Hydrogen bonds are formed between PA chelates and BTA chelates enhancing the density of the conversion film leading to the improvement of corrosion resistance of conversion film on a copper surface with the introduction of BTA.

With the development of energy storage, potassium ion batteries (PIBs) have gradually become a suitable substitute for lithium-ion batteries. Where the layered transition metal oxides cathode materials of potassium ion batteries have attracted much attention due to their high theoretical capacity, unique two-dimensional potassium ion diffusion channels, simple preparation and low cost. In this work, we designed a K_0.5MnO₂@MWCNT@Super P (KMP) composite electrode with P3-type layered structure as the cathode in PIBs through coprecipitation—high temperature sintering method. The SEM results show that the prepared KMP composite electrodes are secondary particles formed by three-dimensional network structures and particles through point–line contact and point–point contact. As a result, the composite electrode with a 7 : 2 : 1 weight ratio of K_0.5MnO₂, conductive carbon (Super-P: MWCNT = 1 : 1) and PVDF delivers a high initial discharge capacity of 112.7 mA h g^–1 at a current density of 20 mA g^–1 and 72.1 mA h g^–1 at 100 mA g^–1. And, it has a capacity retention of 44% at 100 mA g^–1 after 50 cycles. The results show that the unique three-dimensional network structure not only improves the conductivity of K_0.5MnO₂ material, but also effectively alleviates the volume change caused by K⁺ in the charging and discharging process. This study provides a new way to develop layered cathode materials for high energy density potassium ion batteries.

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.