Кафедра фізичної хімії (КФХ)

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Des-Assisted Electrodeposition and Characterization of an Electrocatalyst for Enhanced Urea Oxidation in Green Hydrogen Production
(Ukrainian State University of Science and Technologies, Dnipro, 2025) Protsenko, Vyacheslav S.; Shaiderov, D. A.; Sukhatskyi, O. D.; Butyrina, Tetiana E.; Korniy, S. A.; Danilov, F. I.
ENG: An important task of modern materials science is the development of highly efficient electrocatalysts for green hydrogen production. Specifically, this involves the urea oxidation reaction (UOR), which is an energetically advantageous and attractive alternative to the anodic oxygen evolution reaction, coupled with hydrogen evolution at the cathode. In this work, we present for the first time the use of systems based on a new generation of environmentally friendly room-temperature ionic liquids – deep eutectic solvents (DESs) – for the electrodeposition of electrocatalysts for UOR. The electrochemical performance of electrodeposited nanocomposite Ni–CeO2 electrocatalysts was evaluated in alkaline solution, showing an appreciable reduction in the anodic potential of UOR compared to oxygen evolution, reaching up to approximately 0.2 V at a current density of 0.1 mA cm–2. The obtained results are significant for the development of electrochemical synthesis methods for electrocatalysts used in green renewable energy.
Design, Fabrication and Functional Properties of Titanium Suboxide-Based Composites With Low Noble Metal Content for Electrocatalytic Applications
(Journal of Electrochemical Science and Engineering, 2025) Knysh, Valentina О.; Zhemela, Heorhii; Shmychkova, Olesia B.; Luk'yanenko, Tatiana V.; Velichenko, Oleksandr В.
ENG: Fabrication, design and investigation of functional properties of composite materials based on titanium suboxides with low noble metal content for use in electrocatalysis has been investigated. The study particularly focuses on electrode coatings derived from titanium dioxide modified with platinum and palladium. The structural, electrocatalytic, and corrosion-resistant properties of these materials were systematically investigated. It was demonstrated that thermal treatment significantly enhances the catalytic efficiency of the coatings by reducing the oxygen evolution overpotential and improving the efficiency of hypochlorite synthesis. Optimal thermal treatment conditions (500 °C, 3 hours) were identi-fied, resulting in increased stability of the anodes containing Pt and Pd layers, as evidenced by a service life of 176 hours. The study highlights the potential of these composites for applications in oxygen evolution reactions and hypochlorite synthesis, owing to their high stability, selectivity, and cost-effectiveness.
Effect of Na+ vs. K+ Cations and Carbonate Presence on Urea Oxidation Reaction Coupled with Green Hydrogen Production in Alkaline Media: A Voltammetric and Electrochemical Impedance Spectroscopy Study
(Hydrogen, 2025) Protsenko, Vyacheslav S.; Shaiderov, Denys A.; Sukhatskyi, Oleksandr D.
ENG: This work reports the electrochemical behavior of a nickel hydroxide electrode, electrodeposited in a deep eutectic solvent (DES), in alkaline solutions of varying composition, aiming to elucidate the influence of the cation (Na+ vs. K+), urea, and carbonate ions on the mechanism and kinetics of anodic processes. Cyclic voltammetry and electrochemical impedance spectroscopy were employed to analyze the electrochemical responses of electrode processes in alkaline water electrolysis systems. For the urea oxidation reaction (UOR), the frequency-dependent characteristics were thoroughly characterized, and the impedance response was simulated according to the Armstrong–Henderson equivalent circuit. It was found that the addition of urea significantly transforms the impedance structure, sharply reducing the polarization resistance and increasing the pseudo-capacitive component of the constant phase element at low frequencies, indicating activation of the slow steps of urea oxidation via a direct mechanism and the formation of an extended adsorptive surface. It was demonstrated that, unlike conventional alkaline electrolysis where KOH-based systems are generally more effective, urea-assisted systems exhibit superior performance in NaOH-based electrolytes, which provides more favorable kinetics for the electrocatalytic urea oxidation process. Furthermore, the accumulation of carbonate ions was shown to negatively affect UOR kinetics by increasing polarization resistance and partially blocking surface sites, highlighting the necessity of controlling electrolyte composition in practical systems. These findings open new opportunities for the rational design of efficient urea-assisted electrolyzers for green hydrogen generation.
Electrochemical Corrosion Properties and Protective Performance of Coatings Electrodeposited from Deep Eutectic Solvent-Based Electrolytes: A Review
(Materials, 2025) Protsenko, Vyacheslav S.
ENG: The application of deep eutectic solvents (DESs) as an innovative class of environmentally friendly liquid media represents a significant advancement in materials science, especially for the development and enhancement of structural materials. Among the promising applications, DESs are particularly attractive for the electrodeposition of corrosion-resistant coatings. It is established that corrosion-resistant and protective coatings, including those based on metals, alloys, and composite materials, can be synthesized using both traditional aqueous electrolytes and non-aqueous systems, such as organic solvents and ionic liquids. The integration of DESs in electroplating introduces a unique capacity for precise control over microstructure, chemical composition, and morphology, thereby improving the electrochemical corrosion resistance and protective performance of coatings. This review focuses on the electrodeposition of corrosion-resistant and protective coatings from DES-based electrolytes, emphasizing their environmental, technological, and economic benefits relative to traditional aqueous and organic solvent systems. Detailed descriptions are provided for the electrodeposition processes of coatings based on zinc, nickel, and chromium from DES-based baths. The corrosion–electrochemical behavior and protective characteristics of the resulting coatings are thoroughly analyzed, highlighting the potential and future directions for developing anti-corrosion and protective coatings using DES-assisted electroplating techniques.
Electrodeposition of Ni-Based Composite Coatings Containing Cerium Compounds From a Deep Eutectic Solvent and their Electrocatalytic Performance
(Oles Honchar Dnipro National University, Dnipro, 2025) Protsenko, Vyacheslav S.; Shaiderov, Denys A.; Sukhatskyi, Oleksandr D.; Korniy, Sergiy A.
ENG: This work examines the electrodeposition of Ni-based composite coatings containing cerium compounds from a eutectic mixture of choline chloride and urea (reline), a typical deep eutectic solvent. The data reveal that depending on the concentrations of NiCl26H2O and CeCl37H2O dissolved in reline, coatings containing up to 49 wt.% cerium, present as embedded CeO2, can be formed within an electrochemically deposited nanocrystalline nickel matrix. Variation of the Ni(II) and Ce(III) salt concentrations strongly influences the resulting surface morphology. Reaction schemes for the formation of these composite coatings are proposed, and cyclic voltammetry with successive scan cycles was used to identify the potential windows in which the relevant electrochemical reactions occur in reline-based solutions. The deposited coatings were tested as electrocatalysts for water electrolysis in 1 M NaOH. Special attention was paid to the electrocatalytic activity of the Ni-based composite coatings toward the anodic oxidation of urea, a potential alternative to the oxygen evolution reaction in green hydrogen production. Incorporation of CeO2 into the nickel matrix led to a pronounced enhancement of electrocatalytic activity for hydrogen evolution, oxygen evolution and urea oxidation in alkaline aqueous solution. The proposed composite coatings may find application as multifunctional catalysts for green hydrogen generation. Moreover, adjusting the Ni(II) and Ce(III) concentrations in the deep eutectic solvent-based plating bath enables flexible and controlled tuning of the electrocatalytic behavior of deposited coatings.
Granular Polymers With Immobilized N-Chlorosulfonamide Groups as Alternative Water Disinfectants
(Journal of Water and Health, 2025) Murashevych, Bohdan; Koshova, Iryna; Girenko, Dmytrо V.; Stepanskyi, Dmytro
ENG: In light of the deterioration of microbiological composition of natural and technical water, the development of new approaches to its disinfection is an important technological task. The use of chlorine-active compounds remains the most effective for this purpose, but traditional preparations such as sodium hypochlorite pose a number of environmental risks. This paper describes the processes of treating model microbiologically contaminated solutions with granular styrene-divinylbenzene polymers with immobilized N-chlorosulfonamide groups. In this case, chlorine is released from the polymer surface into the solution due to chlorination of the amine components of the microbial cell. The amount of chlorine released is proportional to the degree of microbial contamination. The main factors influencing the disinfection rate and the characteristics of the chlorine emission process are the intensity of stirring, the type and concentration of the microorganism, and the surface area of the polymer. The treatment is effective against individual Gram-positive and Gram-negative bacteria, including multiresistant ones, fungi, and multi-culture natural media. The use of this method for water disinfection potentially allows avoiding chlorine overdose, minimizing the formation of toxic chlorine-containing by-products, and ensuring long-term protection of water from recontamination during storage.
Influence of Cathode Material on the Electrochemical Synthesis of Sodium Hypochlorite in Coaxial Flow Cells
(Ukrainian State University of Science and Technologies, Dnipro, 2025) Girenko, D.; Murashevych, В.; Demchenko, Р.; Velichenko, О.
ENG: The features of synthesis of sodium hypochlorite solutions in membraneless flow electrolyzers are mainly determined by the electrolyzer design, electrolysis parameters, and electrode material. In most models, titanium is traditionally used for the cathode, while other materials have not been sufficiently studied in this role. This article discusses alternative cathode materials, such as titanium Grade 2 pre-treated in different ways, various types of platinized titanium, palladium-plated titanium, and stainless steel. A comparative analysis of their effect on the efficiency of the electrolysis process and the quality of the resulting solutions is performed. It is shown that smooth titanium Grade 2 is the optimal cathode material for preparing low-concentration (up to 1500 mg/L) sodium hypochlorite solutions in many respects. An increase in the specific surface area of this material reduces the current efficiency of hypochlorite. However, when using titanium, the electrolysis process is the most energy-intensive. To reduce electricity consumption by 20–25%, it is advisable to use cathodes made of platinized titanium. Heat treatment of platinized titanium under air atmosphere additionally leads to an increase in the integral current efficiency of sodium hypochlorite from 65 to 70% and a slight increase in the energy efficiency of synthesis. The cathode material has practically no effect on the sodium chlorate impurity content, and all obtained solutions have sufficiently high purity for medical applications.
Influence of Various Factors on the Emission of Hypochlorous Acid from Sodium Hypochlorite Solutions Into the Air
(Ukrainian State University of Science and Technologies, Dnipro, 2025) Murashevych, B.; Girenko, D.; Lebed, O.; Maslak, H.; Netronina, O.
ENG: Active chlorine compounds are powerful microbicidal agents traditionally used for surface disinfection. Following the COVID-19 pandemic, the potential use of these compounds for air treatment to mitigate the spread of infectious diseases has been actively studied. A promising approach involves developing disinfection systems capable of maintaining a sufficient concentration of the most effective gaseous antimicrobial component of active chlorine –hypochlorous acid (HOCl) – in indoor air. This study investigates the influence of various factors on the emission of HOCl into the air during its bubbling through sodium hypochlorite (NaOCl) solutions. A colorimetric method for determining the total chlorine content in the air has been refined. The effects of key parameters of NaOCl working solutions on the HOCl concentration in the air have been examined. It has been demonstrated that, at a constant pH of the working solution, the total chlorine content in the air is strictly proportional to the HOCl concentration in the solution, which, in turn, can be determined using established molar distribution diagrams of active chlorine species. When electrochemically generated NaOCl working solutions (containing approximately 1100 mg/L of active chlorine) are used without additional composition adjustments, the HOCl concentration in the air can be maintained within the range of 6.0–11.6 mg/m3 . The findings of this study can be applied in the development of fumigation-based air disinfection systems and in the assessment of air contamination risks associated with chlorine-containing compounds.
An Integral Metric for Evaluating Electrocatalytic Activity
(Chemija, 2025) Protsenko, Vyacheslav S.; Makhota, Dmytro O.
ENG: This study introduces an integral metric of electrocatalytic activity, which is based on the comparison of the area under the polarisation curve in current density vs overpotential coordinates over a specific chosen overpotential range. This metric is applied to evaluate and compare several electrocatalysts, allowing for a more comprehensive understanding of electrocatalytic performance. Unlike traditional metrics, which characterise electrocatalyst behaviour under specific conditions (e.g. a particular overpotential or current density), the proposed integral metric provides a broader evaluation over a wide operational range. This approach is particularly useful for electrocatalysts with different Tafel slopes and polarisation characteristics. The metric is shown to be invariant to the shape of the polarisation curve and can be applied even when the exact form of the analytical dependence is unknown. The application of this metric holds promise for both fundamental studies in electrocatalysis and for practical applications in selecting the most efficient electrocatalysts for various technological processes.
Investigation of Structural, Magnetic, Optical, and Photocatalytic Properties of Fe/CoFe2O4 Composite
(MDPI AG, Basel, Switzerland, 2025) Frolova, Liliya A.; Protsenko, Vyacheslav S.; Butyrina, Tetiana E.
ENG: A Fe/CoFe2O4 nanocomposite was synthesized in one step by a hydrothermal method by processing the created iron and cobalt hydroxocomplexes. For precise characterization of the structure and morphology, X-ray diffraction (XRD), Fourier transform infrared spectroscopy, scanning electron microscopy, and ultraviolet–visible diffuse reflectance spectroscopy (UV-vis-DRS) were used. It was found that the obtained samples have a pronounced spinel crystalline structure, with the presence of metallic iron. The crystal size was determined by various methods and was 93–104 nm. The saturation magnetization, determined from the hysteresis loop, was 189.24 Emu/g, and the force coefficient was 602 Oe. UV-vis-DRS studies showed a band gap of 2.1 eV. The photocatalytic degradation of ibuprofen, streptocide, furacilin, methylene blue, and tetracycline was investigated under the influence of UV radiation in the presence of a photocatalyst. It was confirmed that the rate of degradation of pollutants obeys pseudo-first-order kinetics. Analysis of the constant rate of reactions showed that in order of decreasing stability, pharmaceutical drugs can be dissolved as follows: ibuprofen → streptocide → furatsilin → methylene blue → tetracycline. It was found that the ratio of photocatalyst and hydrogen peroxide concentrations is important for the destruction of more stable pollutants. The effect of hydrogen peroxide and catalyst concentrations is extremely strong. For unstable compounds, the most influential factor is the duration of treatment.
New Electrode Materials for Aluminum Production
(Ukrainian State University of Science and Technologies, 2025) Husarova, I.O.; Omelchuk, A.O.; Grigoriev, O.M.; Kraiev, M.V.; Velichenko, Oleksandr В.
ENG: The successful development and implementation of inert anodes in the aluminum industry could significantly reduce or even completely eliminate greenhouse gas emissions. The search for suitable inert anode materials with the necessary combination of properties remains an active area of research. Currently, three main classes of materials are being considered: ceramics, metal-ceramics, and metals. This study aims to develop a new type of composite ceramic material for use as inert anodes in the electrolytic reduction of alumina. Based on an analysis of the requirements for inert anodes in aluminum electrolysis, the oxidation-resistant and conductive ZrB2–MoSi2 composite ceramic is proposed for operation within the required temperature range. It has been demonstrated that these anodes exhibit inert behavior toward atomic oxygen and can operate stably in atomic oxygen atmospheres at temperatures up to 20000C. Furthermore, the feasibility of applying a protective ZrB2–MoSi2 coating to conventional carbon anodes via vacuum arc deposition has been experimentally confirmed. The use of non-consumable anodes with ZrB2–MoSi2 protective coatings is also proposed for the direct electrolysis of lunar regolith at 16000C, enabling oxygen and metal extraction on the Moon.
Towards Sustainable Urea Electro-Oxidation: a Thermodynamic and Green Chemistry Evaluation of Alternative Pathways
(Royal Society Open Science, 2025) Protsenko, Vyacheslav S.
ENG: This study presents a comparative thermodynamic analysis of various pathways for electrochemical hydrogen production coupled with the anodic oxidation of urea, offering a sustainable alternative to the conventional oxygen evolution reaction. For the first time, the feasibility and efficiency of these processes were evaluated using integrated green chemistry metrics, including atom economy and a newly proposed metric, electricity economy, which quantifies the theoretical minimum electrical energy required for the equilibrium formation of reaction products. The analysis demonstrated that urea-oxidation pathways generally require significantly less energy input than water electrolysis. Among the examined reactions, the oxidation of urea to gaseous nitrogen and carbonate ions was identified as the most efficient, with an electricity economy of –4650.83 J mol–1 and an atom economy of 6.4%. However, practical application is hindered by issues such as low product selectivity and high anodic potentials dictated by the redox thermodynamics of commonly used nickel-based catalysts. These findings underscore the need for next-generation electrocatalysts with enhanced selectivity and lower overpotentials to fully exploit the energetic advantages of urea oxidation for green hydrogen production.
Електрохімічні властивості ТiОX–Рt композитів
(Український державний університет науки і технологій, Дніпро, 2025) Книш, В. О.; Шмичкова, О. Б.; Лук’яненко, Т. В.; Веліченко, О. Б.
UKR: Досліджено електрохімічні властивості ТіОх–Рt електродів з різним вмістом платини від 0,3 до 2 мг/см2, нетермооброблені та термооброблені за 5000С впродовж 3 год. Було здійснено вольтамперометричні дослідження зразків у 1 М розчині НСlО4. З отриманих циклічних вольтамперограмах випливає, що катодне відновлення кисеньвмісних сполук платини на термооброблених зразках відбувається за струмів в 1,5–2 рази нижчих, ніж на нетермооброблених, що пов’язано зі зменшенням істинної (активної) поверхні зразків в процесі термооброблення. Електрокаталітичну активність матеріалів досліджено стосовно реакції виділення кисню в 1 М HClO4. Перенапруга виділення кисню на матеріалах, які містять платину, значно нижче, ніж на TiOx електроді. Для нетермооброблених зразків перенапруга виділення кисню зменшується з ростом вмісту платини в покритті. У випадку термооброблених електродів спостерігається така сама тенденція; перенапруга виділення кисню для покриттів, де вміст платини 0,5 мг/см2 і вище, залишається незмінною. На зразку з вмістом платини 0,3 мг/см2 шар металу не є суцільним, а матеріал являє собою пористу структуру з острівцями платини на TiOx. Матеріали з вмістом Pt 0,5 мг/см2 і більше зберігають поруватість, а шар металу суцільний і рівномірний.
Сплав мідь–нікель як потенційний електрокаталізатор для реакцій виділення кисню і окислення карбаміду: вплив анодного оброблення в низькотемпературних евтектичних розчинниках
(Український державний університет науки і технологій, Дніпро, 2025) Махота, Д. О.; Проценко, Вячеслав Сергійович; Бутиріна, Тетяна Євгенівна; Данилов, Фелікс Йосипович
UKR: Проведено експериментальне дослідження, спрямоване на встановлення впливу анодного оброблення сплаву мідь–нікель (~55 мас.% Cu) в низькотемпературних евтектичних розчинниках (DES) на електрокаталітичну поведінку у реакції виділення кисню та електрохімічного окислення карбаміду у водному лужному середовищі 1 M NaOH. Як DES були обрані евтектичні суміші холін хлориду з етилен- гліколем і карбамідом (ethaline і reline, відповідно). Анодне оброблення проводили в потенціостатичному режимі протягом 2,5 годин при потенціалах 0,3; 0,5; 0,7; 1,0; 1,35 і 1,7 В відносно срібного електрода порівняння. Методом лінійної вольтамперометрії показано, що анодне оброблення сплаву мідь–нікель в ethalineі reline за будь-якого з використаних значень електродних потенціалів призводить до збільшення поляризації реакції виділення кисню. Що стосується реакції окислення карбаміду, то за певних значень анодного потенціалу оброблення спостерігається зростання густини струму, тобто зростання електрокаталітичної активності. Специфічний характер впливу оброблення поверхні сплаву Cu–Ni в різних DES та немонотонний характер впливу потенціалу анодного оброблення на електрокаталітичну активність як в реакції виділення кисню, так і електрохімічного окислення карбаміду у лужному середовищі пояснено змінами у морфології поверхні, що приводить до відповідних змін у природі, концентрації і активності каталітичних центрів, які беруть участь у досліджуваних реакціях. Отримані у роботі результати можуть бути використані для розробки процесів електролітичного синтезу «зеленого» водню шляхом електролізу води, в яких реакція виділення кисню замінена на реакцію окислення карбаміду.
Сплав мідь–нікель як потенційний електрокаталізатор для реакцій виділення кисню і окислення карбаміду: вплив анодного оброблення в низькотемпературних евтектичних розчинниках
(Український державний університет науки і технологій, Дніпро, 2025) Махота, Д. О.; Проценко, Вячеслав Сергійович; Бутиріна, Тетяна Євгенівна; Данилов, Фелікс Йосипович
UKR: Проведено експериментальне дослідження, спрямоване на встановлення впливу анодного оброблення сплаву мідь–нікель (~55 мас.% Cu) в низькотемпературних евтектичних розчинниках (DES) на електрокаталітичну поведінку у реакції виділення кисню та електрохімічного окислення карбаміду у водному лужному середовищі 1 M NaOH. Як DES були обрані евтектичні суміші холін хлориду з етилен- гліколем і карбамідом (ethaline і reline, відповідно). Анодне оброблення проводили в потенціостатичному режимі протягом 2,5 годин при потенціалах 0,3; 0,5; 0,7; 1,0; 1,35 і 1,7 В відносно срібного електрода порівняння. Методом лінійної вольтамперометрії показано, що анодне оброблення сплаву мідь–нікель в ethalineі reline за будь-якого з використаних значень електродних потенціалів призводить до збільшення поляризації реакції виділення кисню. Що стосується реакції окислення карбаміду, то за певних значень анодного потенціалу оброблення спостерігається зростання густини струму, тобто зростання електрокаталітичної активності. Специфічний характер впливу оброблення поверхні сплаву Cu–Ni в різних DES та немонотонний характер впливу потенціалу анодного оброблення на електрокаталітичну активність як в реакції виділення кисню, так і електрохімічного окислення карбаміду у лужному середовищі пояснено змінами у морфології поверхні, що приводить до відповідних змін у природі, концентрації і активності каталітичних центрів, які беруть участь у досліджуваних реакціях. Отримані у роботі результати можуть бути використані для розробки процесів електролітичного синтезу «зеленого» водню шляхом електролізу води, в яких реакція виділення кисню замінена на реакцію окислення карбаміду.