Russian Journal of Electrochemistry最新文献

Through a comprehensive characterization approach, this NaTi₂(PO₄)₃/AC nanocomposites study meticulously analyzes the crystal structure, morphology, elemental composition, and electrochemical behavior of these nanocomposites to unlock their potential for energy storage. XRD analysis confirms the successful formation of the composite, revealing distinct peaks characteristic of non-layered activated carbon and crystalline NaTi₂(PO₄)₃. While the Electrochemical characterization shows that the nanocomposite demonstrates excellent rate capability, retaining 90% of its capacitance even after 3500 cycles, while delivering a high energy density of 89 W h kg^–1 at a remarkable power density of 231 W kg^–1. Density functional theory (DFT) analysis indicates that the NaTi₂(PO₄)₃ is a promising candidate for energy storage application due to its combined mechanical stability and good electronic conductivity, attributed to Ti 3d orbitals near the Fermi level. These exceptional combined properties position this novel material as a strong candidate for next-generation energy storage applications.

The corrosion resistance and material properties of tinplate cans used in a food production facility in Serbia were analyzed to identify the causes of corrosion occurring at the junction between the lid and the can body. The composition of the steel sheet, the tin coating, the type of passive layer, and the organic coating were determined using different analytical methods (XRF, SEM/EDS, and FTIR). Corrosion resistance was determined using the EIS method and by directly immersing the samples with an artificial defect in a diluted NaCl solution. The tin coating was passivated with titanium oxide, to which an organic coating was applied. When filled cans are laced, at the joint between the lid and the can body, the organic coating is locally damaged, and subsequently, steel corrosion occurs. The insufficient thickness of the tin coating (~0.1 µm), and pour wet adhesion of the organic coating are the main causes of steel corrosion in the gap between the lid and the can body. The application of the passive layers that ensure good adhesion of the covering organic coating and application an organic coatings of the new generation that have property of self-healing is probably the promising solution for this problem.

The electrocatalytic oxidation of potato starch by potassium and sodium iodate in a two-chamber electrolytic cell on lead dioxide and glassy-carbon electrodes in acidic medium with the oxidant in situ regeneration is studied, in dependence on the current density, substrate concentration, oxidant nature, and reaction temperature. The optimal conditions for the production of the oxidized starch, its dialdehyde, were determined: the electrolysis time 120 min, the ultrasonic treatment time 30 min, the substrate concentration 13.3 g/L, the KIO₃ oxidant concentration 0.93 g/L, the current density 25 mA/cm², the carbonyl group content for PbO₂ 48%; for glassy carbon, 56%. The products were identified by IR and NMR spectroscopy and X-ray diffractometry. The temperature regime and ultrasound treatment of the initial starch are shown to have a significant effect on the periodate oxidation process. Analysis of the IR spectra shows that after the starch electrochemical oxidation, a new absorption band at 1730 cm^–1 appears in the oxidized sample spectrum, related to the aldehyde C=O bond stretching vibrations. The kinetics of accumulation of starch oxidation products is investigated. X-ray diffraction analysis elucidated a change in the ratio between the crystalline component (amylose) and starch amylopectin during the periodate oxidation.

An original method for fabricating Ni–Co electrodes is proposed. The electrochemical behavior of the electrodes as the anodes in an alkaline electrolytic cell is studied. It is found that the electrodes exhibit the catalytic activity toward the oxygen evolution reaction, reducing its overpotential. For example, at a current density of 1 A/cm² and a temperature of 85°C, the overpotential decreases by 390 mV compared to the Ni electrode. The advantage of the electrodes is the absence of any coating on their surface that can exfoliate during the electrode operation and lead to its irreversible degradation. The Ni–Co electrodes are tested in the 6 M KOH solution at a temperature of 85°C and a current density of 300 mA/cm², i.e., under the conditions as close as possible to the operating conditions for the alkaline electrolyzers for 500 h. It is shown that after the tests, the electrode surface remained with no visible signs of degradation such as cracking, exfoliation and other mechanical damage. At the same time, a small but irreversible increase of the voltage is observed in the current–voltage characteristics, which may indicate a decrease of the catalytic properties of the electrode surface.

This study developed a high-performance, flexible electrochemical sensor for detecting glucose and uric acid in sweat. The sensor, based on a screen-printed carbon electrode (SPE), incorporates gold and Prussian blue (PB) as electron mediators. Glucose oxidase (GOx) and uric acid oxidase are then drop-cast onto the modified electrode to complete sensor fabrication. Key performance factors, including enzyme amounts and binder type, were optimized. The flexible glucose sensor showed a linear range of 0–10 µM with a maximum sensitivity of 579.06 µA/mM cm^–2, and 10–100 µM with 32.37 µA/mM cm^–2 sensitivity. The flexible uric acid sensor exhibited a linear range of 4–30 µM with a maximum sensitivity of 341.13 µA/mM cm^–2. Both sensors showed good selectivity and minimal interference from common substances like ascorbic acid, KCl, and NaCl, ensuring reliability in complex environments. In practical tests with real sweat samples, both sensors displayed stable performance, with measured glucose and uric acid concentrations closely matching theoretical values, confirming their potential for accurate detection. A smartphone app displays test results, enabling users to monitor their health without needing prior sensor knowledge.

Fuel cells are efficient power generation devices that directly convert chemical energy into electrical energy through chemical reactions. Fuel cell vehicles powered by proton exchange membrane fuel cells have many advantages, such as low operating temperature, quick start-up, high energy density, high power density, and fast response to load changes. However, the performance of the catalyst in the anode reaction deteriorates sharply due to the extreme sensitivity of Pt atoms to CO in the anode reaction. CO easily occupies the reactive sites of Pt atoms, leading to a significant decrease in the catalytic performance of the anode reaction. Therefore, in this study, the impregnation reduction method is used to introduce transition metal Ni elements to modify Pt/C catalysts to enhance the CO tolerance of Pt-based catalysts. In a H₂ + 100 ppm CO atmosphere, the mass-specific activity (MA) reaches 1.307 A/mg, which is 3.48 times that of commercial Pt/C catalysts The influence of different Ni element ratios on the resistance of Pt-based catalysts to CO poisoning is analyzed, providing a new approach for developing anode catalysts with high CO tolerance.

Ion-exchange membrane in contact with acidic vanadium salt solution represents an object of study by many research teams in the context of its indispensable presence as an element of membrane–electrode assemblies in both all-vanadium redox flow batteries and hybrid flow power sources, which use vanadium compounds in one of the half-cells. In this work, a new method is employed for assessing transport characteristics of the Nafion211 membrane with respect to vanadium ions of high oxidation degrees, i.e., vanadyl (VO²⁺) and vanadate (({text{VO}}_{2}^{ + })) cations, in aqueous sulfuric-acid solutions of varying acidity. The method is based on the measuring of chronoamperograms, i.e. current transients after the applying of potential step to electrode contacting a membrane (pressed up to its surface) under conditions when the current of the vanadyl–vanadate electrochemical conversion at the electrode/membrane interface in the forward or backward direction is limited by the transport of these species from an external solution across the membrane. The short-time segments of the transients were found to be described by the Cottrell dependence (I ~ t^–0.5); both the Cottrell coefficients and the stationary currents are proportional to the reactant concentration at the membrane outer side. Measurement of chronoamperograms as well as their interpretation aimed at the calculating of both the vanadyl and vanadate cations’ diffusion coefficients inside the membrane and their distribution coefficients at the membrane/solution boundary are carried out for varied sulfuric-acid concentration (from 2.2 to 5 M) and the [VO²⁺]/[({text{VO}}_{2}^{ + })] external-solution concentration ratio from 0 to 1. The increase in the acid content was found to lead to the growth of the vanadyl diffusion coefficient in the membrane from 1.76 to 0.84 × 10^–11 m²/s; the vanadate diffusion coefficient falls from 1.89 to 0.8 × 10^–11 m²/s. Meanwhile, the distribution coefficients decreased for both cations: from 0.27 to 0.13 and from 0.21 to 0.12, respectively. It is concluded on the applicability of the method in the analyzing of the ion transport and the equilibrium composition of ion-exchange membranes in contact with a sulfuric-acid–oxovanadium-cation mixed solution.

The objective of this research is to prepare a composite with lower cost and better cyclability than the other cathode materials in lithium ion battery. A ternary composition with high efficiency and low cost containing LiFeO₂ and LiNi_1/2Mn_1/2O₂, was applied instead of pure LiCoO₂ to reduce usage of the percentage Co amount in cathode materials of LIBs, consequently a benefit would be yielded by reducing the cost of cobalt and also by removing its toxic effect in LIBs the environment will be safe. In this study, we synthesized ten samples from mixture of xLiFeO₂, yLiCoO₂, and (1 – x – y)LiNi_1/2Mn_1/2O₂ compounds for preparing suitable cathode electrodes with high initial discharge capacity, large cyclability and inexpensive cost instead of traditional cathode materials. As a result by using Raman Analysis, X-ray diffraction, and electrochemical analyzing, we found that the LiNi_1/6Mn_1/6Fe_1/3Co_1/3O₂ composite has high efficiency and best performance in viewpoint of initial capacity, cyclability, charge capacity, and discharge capacity among these ten composites.

In this study, the layers including Co₃O₄ nanoparticles were fabricated on the nickel foams using an electroplating method to be adopted for oxygen evolution reaction. Various times of 5, 10, and 15 minutes were considered to choose the optimal one for electrodeposition. The experiments were carried out at a temperature of 400°C under air atmosphere. The fabricated layers were electrochemically examined by means of various analyses, consisting of chronoamperometry (ChA), electrochemical impedance spectroscopy (EIS), and linear sweep voltammetry (LSV). Additionally, the layers were structurally and morphologically studied by different techniques such as field-emission scanning electron microscopy (FESEM), X-ray diffraction analysis (XRD), and Fourier transform infrared spectroscopy (FTIR). The optimal electrodeposition time was determined as 10 min at which a layer possessing an appropriate thickness is obtained. However, at the time 20 min, electroplating led to generation of a layer showing a decrease in conductivity. Moreover, at 5 min, the fabricated layer manifested decreased active surface area in the oxygen evolution reaction. Worth mentioning that the layer electrodeposited at 10 min delivered a current density of 61.72 mA/cm² and a Tafel slope of 69 mV/dec, which were recorded at the potential of 1.65 V compared to a standard hydrogen electrode.