Russian Journal of Electrochemistry最新文献

The influences of Sm₂S₃ incorporation on the structural features and electrochemical behavior of Sm₂S₃–SnS composite electrodes were investigated. Both SnS and Sm₂S₃ maintain their intrinsic crystal structures. Sm₂S₃ particles are reasonably dispersed on or among the layered SnS particles at low to moderate loadings, while higher Sm₂S₃ contents lead to partial agglomeration. Sm₂S₃ incorporation affects the charge–storage characteristics of SnS. The cyclic voltammetry (CV) curves of the Sm₂S₃–SnS composite electrodes exhibit non-ideal profiles with distorted capacitive shapes and noticeable faradaic contributions. The Sm₂S₃–SnS composites exhibit improved rate capability and prolonged discharge behavior compared with pristine SnS. A pure Sm₂S₃ electrode prepared and tested under the same conditions was further introduced as a control sample. The comparison confirms that pure Sm₂S₃ is electrochemically active but is not superior to the optimized Sm₂S₃–SnS composites, indicating that SnS plays an active role in constructing an ion-accessible layered framework and improving the utilization of Sm₂S₃ domains. Different Sm₂S₃ loadings favor different electrochemical metrics under different current-density conditions. Electrochemical impedance spectroscopy (EIS) of Sm₂S₃–SnS composite electrode demonstrates a non-monotonic evolution of solution resistance and charge-transfer resistance with increasing Sm₂S₃ content, suggesting changes in interfacial charge-transport pathways. The Sm₂S₃–SnS composite electrodes possess stable cycling performance and high Coulombic efficiency. The possible role of Sm₂S₃ in modulating phase contact and charge–storage characteristics of SnS-based composite electrodes is discussed.

The rising incidence of cadmium in water contamination sources presents a significant threat to environmental and community health, requiring the advancement of precise and selective detection technology. This work examines the electrochemical sensing capabilities of graphene oxide–aluminum/manganese (GO–Al/Mn) nanocomposites for detecting and evaluating of cadmium(II) ions in solutions. An innovative electrochemical sensor utilizing GO–Al/Mn nanocomposites (NCs) was synthesized to detect Cd(II) in solutions with high sensitivity and selectivity, employing a manually controlled dynamic electrochemical approach via a three-electrode system. Characterization of structural, morphological, and compositional aspects was conducted using FTIR, XRD, SEM, EDX, BET, TEM, and XPS, validating the effective incorporation of Al/Mn oxides with GO sheets. Thermal gravimetric analysis (TGA) indicated a total weight loss of over 90% for pristine graphene oxide (GO), in contrast to roughly 24.63% for GO Al/Mn nanocomposites over the temperature range of 30–800°C, underscoring the enhanced thermal stability conferred by metal oxide functionalization. The electrochemical assessment revealed a detection limit (LOD) of 1.65 µM and a quantification limit (LOQ) of 5.00 µM, exhibiting a linear response range of 100–700 µM Cd(II) and a high correlation coefficient (R² = 0.9989). The improved performance is due to the synergistic impacts of GO’s oxygenated functional groups, Al centers that attract Cd²⁺, and Mn redox sites that promote electron transport. Sensors demonstrated high selectivity for various interfering substances in the matrix of aqueous solutions and actual water samples. These findings underscore the promise of GO–Al/Mn NCs as effective, economical, and eco-friendly platforms for the environmental monitoring of Cd(II) pollutants.

Literature data on the oxidative degradation of azo dyes are summarized. Processes of photoelectrochemical oxidation with various approaches to the removal of azo dyes from wastewater are considered. Recent advances in photoelectrochemical techniques designed to enhance degradation efficiency are discussed, including photoelectrochemical oxidation (PEO), photoelectro-Fenton (PEF), and solar photoelectro-Fenton (SPEF). The key problems are discussed such as the use of semiconductor materials as electrodes, the effect of operational parameters on dye degradation in wastewater, the design of reactors, and the combined photoelectrochemical oxidation systems including those with integrated fuel cells. A comparative analysis of electrochemical anodic oxidation (AO) versus PEO processes for azo dye treatment is provided. The data on identification of azo dye degradation products and their toxicity are presented.

How to regular Li plating/stripping behavior is a scientific and engineering issue to accelerate commercial process of Lithium metal batteries (LMBs). Herein, lithiophilic N, P-codoped carbon (NPC) microsphere is introduced to modify commercial Cu foil as lithium free anode for LMBs. Electrochemical results show that the NPC-1000 modified Cu foil (NPC@Cu) delivers a stable Coulombic efficiency (CE) up to 98.6% for over 175 cycles. The as-prepared NPC@Cu–Li anode efficiently avoids Li dendrite and/or pulverization phenomenon even at a current density as high as 2.0 mA cm^–2. As a proof, the NPC@Cu–Li||NPC@Cu–Li symmetric cell is successfully operated over 1800 h without obvious voltage fluctuations. More impressively, NPC@Cu–Li||LiFePO₄ full cell exhibits a small capacity attenuation rate of 14.6% after 350 cycles at 0.5 C and a desirable rate capability. Our work supplies a new perspective to develop commercial Cu foil based lithium free anode by surface modification with lithiophilic materials.

A novel electrochemical sensor for enrofloxacin (ENR) was constructed by drop-coating multi-walled carbon nanotubes on a graphite electrode, followed by electropolymerization of p-aminobenzoic acid. The sensor showed a linear response from 0.02 to 50 μM, with a detection limit of 0.0036 μM. It exhibited good selectivity, reproducibility, and successful application in spiked milk samples (recoveries 99.0–104.1%), offering a cost-effective and simple strategy for antibiotic residue monitoring.

The effect of the aqueous electrolyte ion size and mobility on the electrochemical characteristics of supercapacitors with the Carbonopon V-active carbon-fiber electrodes is analyzed. Solutions of 1 M sodium salts (NaCl, NaNO₃, Na₂SO₄, Na₂CO₃, CH₃COONa, CH₃CH₂COONa, CH₃CH₂CH₂COONa, CH₃CH₂C(CH₃)₂COONa, CH₃(CH₂)₆COONa), and those of 1 M potassium salts (KCl, KNO₃) are used as electrolytes. The anion structure and size are determined using the ChemSketch software (ACDLabs); the pore size distribution in the electrode material is estimated using BJH nitrogen adsorption–desorption measurements. The electrochemical characteristics of the supercapacitors are studied by the galvanostatic charge‒discharge and cyclic voltammetry methods. The obtained results showed the specific capacitance to be determined by the nature of the salt anion rather than by that of the cation. The using as ionogens of the salts whose anion diameter in the non-hydrated state does not exceed 0.6 nm ensures the functioning of laboratory cells with high resource stability, typical for double-layer-based supercapacitors. The use of organic salts with the anion size of about 0.6 nm and more results in a faster specific capacitance decay with increase in the current density above 0.5 A/g as compared to inorganic salts. The values of specific capacitance at current densities not exceeding 0.5 A/g decreased, depending on the salt anion, in the following order: ({text{NO}}_3^ - ) > Cl^– ~ CH₃COO^– ~ C₂H₅COO^– > ({text{SO}}_4^{2 - }) ~ ({text{CO}}_3^{2 - }) > CH₃СH₂C(CH₃)₂COO^– > CH₃(CH₂)₆COO^–. No straightforward dependence of the specific capacitance on the ionic mobility in the studied electrolytes is found. The specific capacitance is affected by the size of both hydrated and non-hydrated anions.

Equilibrium alloys of the Ag–Sn–S system in the Ag₂S–SnS₂–S composition range are studied by electromotive forces (EMF) measurements of concentration cells relative to a silver electrode cell with Ag₄RbI₅ solid electrolyte over the 300–390 K temperature range. A linear equation for the EMF temperature dependence is obtained, from which the silver partial molar functions in the alloys are calculated. Based on the solid-phase equilibria diagram of the Ag–Sn–S system, a virtual potential-determining reaction is established. This reaction is used in the calculating of the standard thermodynamic formation functions and standard entropy of the Ag₈SnS₆ low-temperature modification. By combining the obtained data with the phase transition thermodynamic functions of the compound, the corresponding functions for its high-temperature modification are calculated.

Enzyme immobilization is one of the key factors in constructing high-performance bio-devices. Herein, a honeycomb-like three-dimensional nanoporous gold (3DHNPG) was electrodeposited by an one-step dynamic gas bubble template method for enzyme immobilization and enzyme-electrode fabrication. A CS/GOx/3DHNPG/Au electrode was prepared simply by cast-coating glucose oxidase (GOx) and chitosan (CS) successively on the 3DHNPG modified Au electrode and air-dried. The thus-prepared CS/GOx/3DHNPG/Au electrode responded linearly to glucose from 0.01 to 4.4 mM with a sensitivity of 166 μA mM⁻¹ cm⁻² and a limit of detection of 1.2 μM (first-generation biosensing mode). Due to the special porous structure of 3DHNPG with large specific surface area, as well as high catalytic activity for H₂O₂ oxidation, the sensitivity of CS/GOx/3DHNPG/Au electrode for glucose sensing is greatly enhanced, which is larger than those of CS/GOx/Au_plate/Au electrode, CS/GOx/Au electrode, and most reported GOx-based enzyme electrodes. This 3DHNPG-based enzyme electrode also worked well in the second-generation biosensing mode and as a bioanode in a monopolar biofuel cell. The 3DHNPG with great convenience in synthesis, outstanding biocompatibility and electron-conductibility may be an excellent matrix choice to immobilize biomolecules for constructing high-performance biodevices with promising applications.

An electrode based on Cu–Al layered double hydroxide-modified carbon paste was successfully developed for analyzing residual free chlorine levels in water. To evaluate the electrode, its structure, composition, and electrochemical performance were characterized by X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), Fourier-transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FESEM), and various electrochemical techniques. The electrochemical response to free chlorine was examined for various parameters, including accumulation time, pH, scan rate, and electrolyte effect. This study used differential pulse voltammetry (DPV) to measure free chlorine, as this technique is highly sensitive and efficient. A linear range of 0.0005 to 1000 µM, with a detection limit of 0.00015 µM (S/N = 3), was obtained under optimal conditions. The electrode exhibited satisfactory reproducibility and selectivity. The proposed sensor successfully quantified residual free chlorine in real water samples.

The transport properties of sodium nitrate (NaNO₃) and ammonium nitrate (NH₄NO₃) in aqueous 2-butoxyethanol (mass fractions: 0.20, 0.40, and 0.60) mixtures were examined using electrical conductivity measurements at 298.15, 303.15, 308.15, and 313.15 K. The experimental conductance data were analyzed using the Fuoss conductance–concentration equation (1978) to evaluate ion association parameters and to gain insights into the ion–solvent and ion–ion interactions within the mixed solvent systems. The estimates of the individual ionic contributions to the limiting molar conductance were also made in this analysis. The calculated values of ion association parameters suggest a weak electrostatic ion solvent interaction for these two salts in aqueous 2-butoxyethanol mixture. Moreover, the electrolytes were found to exist predominantly as free ions across all solvent compositions and within the entire temperature range investigated in this study. The influence of temperature and solvent composition on the association constants and single-ion conductivities of the electrolytes was systematically examined and discussed. The Walden products of the ions exhibited significant deviations with changes in temperature and solvent composition.