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.
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.
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.
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.