Russian Journal of Electrochemistry最新文献

Using open-circuit potential measurements, Tafel extrapolation, and electrochemical impedance spectroscopy, the effect of 1.7, 4.5, and 7.5 at % titanium additives on the rate and characteristics of Al–Ti alloys’ surface corrosion in 0.6 M NaCl, 0.02 M, and 0.08 M NaOH aqueous solutions is studied. In salt solutions, titanium alloys exhibit a more positive open-circuit potentials relative to pure aluminum; its shift depends on the amount of intermetallic inclusions. These inclusions introduce intercrystalline-boundary defects into the aluminum surface, which is also reflected in a slight increase of the corrosion current. In alkaline solutions, in addition to the increasing the open-circuit potential, they contribute to an increase in its stabilizing time, due to the difference in their corrosion rates as compared to the aluminum phase. Electrochemical methods showed the surface layer of products of interactions with alkaline solutions to slow down the corrosion significantly; yet, it did not provide any protective passivity neither at pure aluminum, nor at Al–Ti alloys.

Lithium–carbon dioxide (Li–CO₂) batteries hold significant promise as next-generation energy storage devices with the potential for high theoretical energy density and carbon utilization. However, their practical application is hindered by large overpotential, sluggish redox kinetic and the electrolyte decomposition. To address these challenges, the design of a Cu(I)–betanin redox mediator modified aprotic electrolyte was firstly investigated to reduce charging overpotential and improve cycling stability in Li–CO₂ battery. Betanin, a natural pigment from beets, was chemically coordinated with Cu(I) ions to form a redox-stable Cu(I)–betanin complex. In Li–CO₂ coin cell, the Cu(I)–betanin mediator increased output voltage of 3.05 V, enlarged a specific capacity of 5800 mA h g^–1 based on Super P carbon mass and led to a 40% increase in cycle life compared to Li–CO₂ cell without the redox mediator. Moreover, post-cycling analyses confirmed minimal electrode passivation demonstrating that the Cu(I)–betanin redox mediator effectively mitigated detrimental side reactions and extended electrode longevity. The use of this cost-effective, environmentally benign additive underscored a viable strategy for optimizing electrolyte formulations and paved the way for practical implementation of high-performance Li–CO₂ batteries.

This study successfully developed a porous NiS nanosheet sulfur carrier based on MOF derivatives through a multi-level structural design strategy, thereby significantly improving the electrochemical performance of lithium–sulfur batteries. Single-crystal β-Ni(OH)₂ nanosheets synthesized by the urea hydrothermal method were used as templates to construct Ni(OH)₂@MOF-74 heterostructures through in situ coordination reactions. Then, a NiS nanosheet carrier with graded pores was prepared through a precisely controlled carbonization sulfurization process. This carrier exhibits triple functional advantages: the MOF-derived three-dimensional conductive carbon network (conductivity > 10^–2 S/cm) ensures efficient electron transfer; the exposed NiS (101) crystal plane achieves strong chemical anchoring and efficient catalytic conversion of lithium polysulfides. The graded pore structure offers a high sulfur loading capacity of 64 wt % in the electrode, along with fast ion transport channels. Based on these characteristics, the NiS/S composite positive electrode achieved an initial discharge capacity of 1520 mA h/g at a high rate of 2 C. Still, it maintained a capacity of 720 mA h/g after 300 cycles (a capacity retention rate of 47.4%), with a stable Coulombic efficiency of over 99.8%. Impedance spectroscopy revealed a unique interface activation phenomenon, with a 68% decrease in charge transfer resistance and a suppression of the polysulfide diffusion coefficient to the order of 10^–14 cm²/s after cycling. These breakthroughs are attributed to the synergistic effect of “morphology genetics pore regulation interface optimization,” providing new material design ideas for practical lithium sulfur batteries with high energy density and long cycle life.

Electrochemical characterization of 316L stainless steel electrodes for alkaline water electrolysis was conducted through impedance spectroscopy (10 mHz–100 kHz), Tafel analysis, and thermal modeling. Impedance measurements revealed charge transfer resistance of 2.8 ± 0.2 Ω cm², five-fold higher than ohmic resistance (0.52 ± 0.03 Ω cm²), identifying kinetic limitations as the primary optimization target. Tafel analysis demonstrated Volmer step rate-limitation with slopes of 130 ± 5 mV/decade for hydrogen evolution reaction (HER) and 85 ± 3 mV/decade for oxygen evolution reaction (OER), indicating water dissociation as the critical kinetic barrier. Exchange current densities of (2.3 ± 0.3) × 10^–7 A/cm² (HER) and (5.8 ± 0.5) × 10^–6 A/cm² (OER) were determined. Temperature-dependent measurements yielded activation energies of 48 ± 3 kJ/mol (HER) and 35 ± 2 kJ/mol (OER). A six-cell 5 kW electrolyzer system achieved 68.5% thermodynamic efficiency (LHV basis) with an 8.5-min thermal time constant. Field validation over 12 months in Turkey and Uzbekistan demonstrated operational stability exceeding 5100 h with hydrogen production at 62% DC-to-hydrogen efficiency when directly coupled with photovoltaic systems. The electrochemical characterization provides fundamental understanding of 316L stainless steel as a cost-effective electrode material for alkaline electrolysis in renewable energy applications.

Cooked guinea fowl eggshells were used to modify a glassy carbon electrode for paraquat detection. Characterization (FTIR, XRD, BET, TGA) confirmed calcite composition with increased surface area upon cooking. Electrochemical studies showed enhanced affinity and faster electron transfer. The sensor achieved a 0.209 nM detection limit, with good selectivity and reproducibility, and performed well in real water samples, offering a low-cost eco-friendly monitoring tool.

Pd(WC_1–x)/C-electrodes were obtained by redox reaction between Pd²⁺ ions and tungsten carbide WC_1–x. The palladium mass released in 2 h from of 0.1 M PdCl₂ + 0.5 M H₂SO₄ solution is 0.60 ± 0.03 mg/cm² (the electrode geometric surface); the specific surface area is 8.5 m²/g. The palladium is found to be reduced to a zero oxidation degree during currentless deposition; the basic products of WC_1–x oxidation are tungsten oxides. The catalytic effect of the Pd(WC_1–x)/C-electrodes in the hydrogen evolution reaction and oxidation of formic acid reaction has been discovered.

To investigate the effect of selenization degree on the electrochemical performance of iron selenides, Fe_xSe_y/carbon composites with different selenization degrees are successfully synthesized via a solid-state reaction using ferric citrate as the precursor, by regulating the reaction temperature and Fe/Se molar ratio. Structural characterization reveals that reaction temperature is the key factor determining the phase composition: with increasing temperature, the selenization degree decreases gradually, showing a phase evolution law of FeSe₂ → Fe₃Se₄ → Fe₇Se₈. Electrochemical tests indicate that Fe₃Se₄ exhibited the optimal reversible capacity (754.5 mA h g^–1) and cycling stability (86.7% capacity retention after 100 cycles) as lithium-ion batteries anode, attributed to the possible synergy between faradaic redox reactions and capacitive storage. In contrast, FeSe₂ possessing a better conductivity shows better capacity retention (75.0%) as sodium-ion batteries. These studies provide valuable insights for designing high-performance iron selenide-based anode materials for batteries.

Electrochemical hydrogen compression technology is a promising alternative for hydrogen compression due to its simultaneous compression and purification, high efficiency, and simple design. One of the main problems in electrochemical hydrogen compressors is to improve the properties of membranes such as proton conductivity, mechanical strength, low hydrogen crossover. Here we report the properties of sulfonated poly(ether ether ketone) composite membranes reinforced with cellulose nanocrystals (CNCs) for the electrochemical compression systems. The physicochemical properties, including the morphology of composite membranes, water uptake, mechanical strength, ion exchange capacity and proton conductivity were evaluated. The mechanical strength of composite membrane with 3 wt % CNCs showed high tensile strength of 26.0 MPa, and proton conductivity was highest among evaluated membranes as 0.209 S/cm at 90°C. The performance of electrochemical hydrogen compressors was tested for voltage, compression time, and energy efficiency at pressures up to 50 bar. As a result, the composite membrane reinforced with CNCs showed improved energy efficiency and lower hydrogen crossover in electrochemical hydrogen compressor systems.

This study investigates the use of electrochemical impedance spectroscopy (EIS) and adaptive neuro-fuzzy inference system (ANFIS) modeling to predict the concentration of butyric and acetic acids in a fermentation broth. Initially, a simulation of the glycolysis process was conducted to produce butyric acid and acetic acid from glucose. Using insights from the simulation data, mixtures of acetic and butyric acids were prepared at known concentrations. EIS measurements were performed on these mixtures to extract impedance parameters, which were subsequently fitted to equivalent circuit models. The extracted parameters served as inputs for the ANFIS model, which was trained to establish a relationship between electrochemical parameters and acid concentrations. The developed ANFIS model acts as a soft sensor, enabling accurate prediction of acid concentrations in fermentation broth based on electrochemical data. This approach offers a novel method for real-time monitoring and control of fermentation processes, enhancing efficiency and product quality. The findings demonstrate the potential of combining EIS and ANFIS for advanced process analytics in biotechnological applications. Future work will focus on validating the model with diverse fermentation conditions and scaling up the methodology for industrial use.

In this paper reduced graphene oxide/activated carbon (rGO/AC, GAC) composite modified by PbSO₄ (PbSO₄–rGO/AC, PGAC) as the additive to negative active material (NAM) of lead acid battery (LAB) was fabricated and its effect on high rate partial state of charge (HRPSoC) cycle life was investigated. To fabricate PGAC, the powder of AC was added to graphene oxide suspension and reduced by glucose. GAC powder was immersed in Pb(NO₃)₂ solution to allow lead ion (Pb²⁺) adsorption on GAC. And by reacting lead ion (Pb²⁺) which was adsorbed on the surface of rGO/AC and sulphate ion (({text{SO}}_{4}^{{2 - }})), PGAC composite was obtained. X-ray diffration (XRD) and scanning electron microscopy (SEM) was used for the structural characterization of the PGAC and electrochemical measurement was carried out by using cyclic voltametry (CV), linear sweep voltametry (LSV), galvanostatic charge–discharge (GCD). The results showed that the addition of PGAC composite (PbSO₄ : GAC = 26 : 74 wt ratio) to NAM at 2 wt % increased HRPSoC cycle life by 343% from 14 768 to 65 477.