Russian Journal of Electrochemistry最新文献

The work is focused on the analysis the impact of the composition of a composite electrolyte comprising a disubstituted ammonium salt of phosphotungstic acid and sulfonated calixarene on the characteristics of solid-state potentiometric sensors for hydrogen and carbon monoxide, including their simultaneous detection in air. The response time of the CO sensors is shown to be independent of the composition of the composite electrolyte, with a value of approximately two minutes for 0.1 vol %. The study also observed two types of open circuit voltage, depending on the electrolyte composition. The sensors demonstrated selectivity for CO, detecting it in the H₂–CO–air atmosphere at concentrations comparable to H₂ concentrations.

The electrochemical machining (ECM) of the outer surface of rotating cylindrical workpiece using a cylindrical cathode with a partially insulated surface is simulated. It is shown that partial insulation of tool electrode (TE) surface enables increasing the localization of the metal dissolution on the desired area of the workpiece surface. The degree of localization increases with a decrease of the non-insulated TE part and a decrease of the minimal interelectrode gap used in ECM. Partial insulation of TE surface leads to a certain decrease in the ECM productivity; however, the edge effect at the boundary between the insulated and non-insulated parts of TE partially compensates for this drawback.

Thermal and electrical properties of solid solution and compositional samples in the Ba₂In₂O₅–Ba₂InNbO₆ quasi-binary system are investigated. The samples were shown to reversibly interact in a humid atmosphere at temperatures below 600°C with water vapor, to form proton defects. The hydration process is accompanied by a significant increase in the total electrical conductivity, due to the proton transfer contribution. Below 500°C in humid air the samples are predominantly the proton conductors. A compositional effect of proton electrical conductivity is established.

The study is focused on the competitive ionic and molecular transport characteristics of four polymer gel electrolyte compositions synthesized through the radical polymerization of polyethylene glycol diacrylate, incorporating LiBF₄, 1-ethyl-3-methylimidazolium tetrafluoroborate, and various organic solvents: dioxolane, diglyme, tetraglyme, and ethylene carbonate. The aim was to identify a composition with the Li⁺ cation highest mobility. Flexible films of the polymer gel electrolytes were analyzed using differential scanning calorimetry, thermogravimetric analysis, and Fourier-transform infrared spectroscopy. The ionic and molecular transport features were investigated using pulsed field gradient NMR in conjunction with electrochemical impedance spectroscopy. The total conductivity of the systems ranged from 1.8 to 4.1 mS cm^–1 at room temperature. Despite the high ionic conductivity of the EC-containing composition, the Li⁺ cation mobility at room temperature increased in the following order: Li⁺(ethylene carbonate)₄ < Li⁺(dioxolane)₄ < Li⁺(tetraglyme) < Li⁺(diglyme)₂. Calculation of the lithium cation hydrodynamic radius revealed that for Li⁺(ethylene carbonate)₄ and Li⁺(dioxolane)₄, the radius decreased with rising temperature; for Li⁺(diglyme)₂, remained nearly constant; for Li⁺(tetraglyme), exhibited an abnormal increase. This unusual behavior is likely due to the re-solvation of the lithium cation from the polymer matrix into tetraglyme. In the assessing of the polymer gel electrolytes compatibility with metallic lithium, the electrolyte compositions containing tetraglyme, diglyme, and ethylene carbonate are found to show promise for further research and potential application as electrolytes in lithium power sources.

This work presents a comprehensive study of the synthesis, structural, and electrochemical characterization of pure and magnesium-doped strontium carbonate (SrCO₃) nanoparticles. Powder X-ray diffraction (XRD) analysis confirmed the orthorhombic phase of SrCO₃ and the presence of MgO in the doped samples. Crystallite sizes and lattice strains were determined using the Debye–Scherrer and Williamson–Hall equations, revealing compressive strain in pure SrCO₃ and significant structural changes with Mg doping. Scanning electron microscopy (SEM) displayed rod-like SrCO₃ particles, which diminished in size with increased Mg content. Energy-dispersive X-ray spectroscopy (EDAX) confirmed the elemental composition, showing enhanced oxygen content with Mg doping. Raman spectroscopy identified shifts in vibrational modes due to Mg addition. Electrochemical performance, investigated via cyclic voltammetry (CV), revealed that lower Mg doping (3%) enhanced specific capacitance at low scan rates and current densities. Electrochemical impedance spectroscopy (EIS) showed increased resistive behavior and capacitive properties with higher Mg content, while open circuit potential (OCP) analysis indicated improved electrochemical stability in Mg-doped samples. The results demonstrate the potential of Mg-doped SrCO₃ for applications requiring enhanced electrochemical performance.

The electrochemical behavior of a series of isomers of methoxyphenoxy derivatives of cobalt phthalocyanine {CoPc[4-(x-OСH₃OPh)]₄ and CoPc[3-(x-OСH₃OPh)]₄, where x = 4′, 3′, or 2′} in alkaline aqueous solutions, and also of ZnPc[4-(x-OСH₃OPh)]₄, where x = 4′, 3′, or 2′, in the CH₂Cl₂ medium is studied for the first time using cyclic voltammetry. The electrochemical behavior and the electrocatalytic activity of cobalt phthalocyanines in the reaction of dioxygen electroreduction is analyzed depending on the functional substitution in the macrocycle molecule. For CoPc[4-(x-OСH₃OPh)]₄ and CoPc[3-(x-OСH₃OPh)]₄, the processes of oxidation (Co²⁺ ↔ Co³⁺) and reduction (Co²⁺ ↔ Co¹⁺) of the central metal ion are observed as well as two sequential stages of the one-electron electroreduction of the phthalocyanine ligand. It is found that these cobalt phthalocyanine derivatives can serve quite efficiently as the systems for dioxygen electroreduction. For ZnPc[4-(x-СH₃OPh)]₄, where x = 4′, 3′, or 2′, the formation of polyphthalocyanine films is observed during the monomer electrooxidation in dichloromethane.

The two title papers are discussed critically. The authors’ methodology contains a number of significant errors and inaccuracies. Problems with inappropriate citations, and incorrect mathematics are pointed out, backed up by our own simulation.

Metal-free N, O double-dop catalysts play an important role in oxygen reduction reactions. However, there is no N, O double-doped metal-free oxygen reduction reactions (ORR) catalyst driven by COF. Herein, a novel metal-free electrocatalyst with N and O doped for oxygen reduction was prepared by JUC‑626 as a precursor and carbonized at high temperature under the protection of N₂ atmosphere, and its catalytic activity at different carbonization temperatures was explored. Among them, JUC-626-600 exhibits excellent oxygen reduction activity, and it exhibits a half-wave potential of up to 0.70 V at 0.1 M KOH. This work reveals the importance of NO heterogeneous catalysts with metal-free COF as precursors.

A highly sensitive electrochemical sensor was developed for the detection of the novel antihypertensive drug lercanidipine (LCP). Using zirconium oxychloride (ZrOCl₂·8H₂O) and graphene oxide (GO) as raw materials, polydiallyldimethylammonium chloride (PDDA) as the eco-friendly reducing agent, nano-zirconium dioxide/reduced GO/PDDA (ZrO₂–rGO–PDDA) composite was prepared by hydrothermal synthesis with doped cerium chloride. Transmission electron microscopy, Fourier transform infrared spectrum, and electrochemical impedance spectroscopy were employed to characterize ZrO₂–rGO–PDDA composite. The electrochemical behavior of LCP at ZrO₂–rGO–PDDA modified glassy carbon electrode (ZrO₂–rGO–PDDA/GCE) was studied by voltammetry. Under optimized measurement conditions, the linear plot between the peak current of LCP and its concentration was found within the range of 4.00 × 10^–7–1.58 × 10^–4 mol/L, with a detection limit of 8.26 × 10^–8 mol/L. This new sensor was employed successfully to determine the content of LCP drug on the market. The spiked recovery experiments showed that the recoveries of LCP ranged from 97.78 to 101.04%. The developed sensor exhibits high sensitivity and accuracy for the determination of LCP.