arXiv subjects

Vitaly V. Chaban

Publications and source records attributed to Vitaly V. Chaban.

At least 19 recordsLinked to original sources

arXiv2026

Ozonation of Dielectric Fosters Self-Healing Efficiency in Metalized-Film Capacitors: Quantum-Chemical Simulation

Metalized-film capacitors (MFCs) employ polymer organic dielectrics like polypropylene (PP) and polyimide (PI), in which self-healing is seen as a key advantage. However, the performance of self-healing depends on specific chemical mechanisms involved. The formation of semiconductive carbonaceous soot represents a critical failure risk. This study investigates how oxygen atom impregnation through ozonation of the dielectric material tunes the composition and electrical conductivity of breakdown products in the PP and PI systems with aluminum-zinc electrodes. We revealed, at the atomistic level, that oxygen atoms tend to remove a fraction of carbon atoms from the semiconductive soot by oxidizing carbon into carbon monoxide in both polymers. In PP, oxygen fraction linearly increases gas mass fraction, thereby reducing soot fraction. In PI, the gas/soot ratio effect of oxygen content is less drastic, still clearly positive. The PP soot conductivity decreases uniformly as larger fractions of oxygen atoms are added. In turn, the PI conductivity drops to ~1500 S/m quickly. The PI soot exhibits narrower band gaps compared to that of PP. The oxygen fraction non-monotonically tailors band gaps, which generally increase. To summarize, ozonation enhances MFC reliability by increasing gas species fraction and reducing soot conductivity. We hereby provide numerical molecular-level insights to rationalize self-healing performance enhancement through polymer ozonation.

cond-mat.mtrl-sci↗

arXiv2025

Polyurethane-Inspired CO2 Chemisorbent: Ab Initio Reaction Profiles

Polyurethane (PU) and its numerous fine-tuned derivatives are widely employed as CO2 scavengers thanks to (1) physisorption and (2) functionalization of the PU backbone with other CO2 sorbents. In the present work, it has been unraveled why PU cannot exhibit CO2 chemisorption, despite possessing the nitrogen docking sites and exhibiting strong electrostatic sorbent-sorbate interactions. Furthermore, a few types of spatial separation of the active sorption sites have been proposed to unleash the chemisorption functionality of PU. By comparing various structural modifications of PU by using the in-silico methodology, we have identified that CO2 chemisorption by PU takes place in the case of implementing methyl and ethyl fragments between the oxygen and nitrogen atoms of PU. Herewith, the introduction of the ethyl moiety even makes CO2 chemisorption energetically favorable relative to physisorption. The reported specific progress on materials design represents an obvious practical value for chemical engineers developing inexpensive CO2 scavengers.

physics.chem-ph↗

arXiv2024

Chemical Compositions of Soot Samples in Gold Electrode Capacitors: Molecular Simulations

Electrical breakdown in a dielectric capacitor occurs when the electric field strength across the dielectric material exceeds its breakdown strength. A conductive channel through the dielectric emerges, resulting in a sudden surge of current. Self-healing represents a phenomenon of restoration of a capacitor's performance. The efficiency of self-healing depends on the products of high-temperature decomposition of the electrode and dielectric. We report atomistic simulations of the soot's chemical composition in the case of gold electrodes and four popular dielectric polymers: polypropylene (PP), polyethylene terephthalate (PET), polycarbonate (PC), and polyimide (PI). We unravel that gold atoms form clusters within the carbon-rich soot, limiting their interactions with non-metal elements. The oxygen atoms of PET, PC, and PI act as stabilizers of gold thanks to electrostatic attraction. Compared to zinc, gold equalizes the soot conductivity in all samples but does not impact polymer gasification. The suitability of dielectrics for self-healing must be rated based on the volatile by-products: PP > PC > PET > PI. Mind that PP issues three times more gases than PI. Therefore, the size of semiconducting soot is substantially smaller in the case of PP than in the case of PI. The obtained numerical results provide unprecedented physical insights into the phenomenon of self-healing and clearly drive the efforts to extend the lifespans of the metalized film capacitors.

cond-mat.mtrl-sci↗

arXiv2024

Insulator and Electrode Materials Marginally Influence Carbonized Layer Conductivity in Metalized-Film Capacitors

Capacitor self-healing is a generalized term to describe physical and chemical processes restoring the functionalities of a dielectric capacitor after an electrical breakdown. The efficacy of self-healing depends on the elemental composition of a metalized-film capacitor. We report atomistic simulations of self-healing from a chemical perspective proving the impossibility of tuning the electrical conductivity of the soot by finding an interplay of various polymers and electrodes. All investigated soot samples turn out to possess carbon-rich semiconducting skeletons with numerous unsaturated C-C covalent bonds. They exhibit electrical conductivities of the same order of magnitude, irrespective of initial chemical compositions and properties of the chosen insulating polymers. Upon reporting the new results, we discuss less evident approaches to diminish the soot conductivity. We conclude that the quality of capacitor self-healing can be assessed by counting gaseous by-products of electrical breakdown or evaluating the volume of the solid-state semiconducting counterpart.

cond-mat.mtrl-sci↗

arXiv2024

The role of potential energy landscape research in the development of new electrolyte solutions

The development of new electrolyte solutions with improved characteristics is a key challenge for creating high-performance batteries, fuel cells, supercapacitors, and other electrochemical devices. The study of the potential energy landscape (PEL) plays an important role in this process, providing information about the interactions between solution components at the molecular level. In this work, we review the practice of applying PEL research methods based on classical and quantum-chemical algorithms to analyze the structure, dynamics, and thermodynamic properties of electrolyte solutions. Intermolecular and ion-molecular interactions at the microscopic level, which determine the macroscopic properties of the electrolyte solution, are considered in detail. The importance of identifying stable configurations of ions and their solvates is emphasized. PEL analysis allows for the systematic determination of the most probable structures and complexes formed in solution, which is important for understanding ion transport mechanisms. The study of the PEL allows for the determination of the energy barriers that must be overcome for ion migration, which is related to the conductivity of the electrolyte. The application of PEL research methods in combination with experimental data opens up new possibilities for the rational design of electrolyte solutions with desired physicochemical properties.

cond-mat.mtrl-sci↗

arXiv2024

Self-Healing in Dielectric Capacitors: a Universal Method to Computationally Rate Newly Introduced Energy Storage Designs

Metal-film dielectric capacitors provide lump portions of energy on demand. While the capacities of various capacitor designs are comparable in magnitude, their stabilities make a difference. Dielectric breakdowns - micro-discharges - routinely occur in capacitors due to the inevitable presence of localized structure defects. The application of polymeric dielectric materials featuring flexible structures helps obtain more uniform insulating layers. At the modern technological level, it is impossible to completely avoid micro-discharges upon device exploitation. Every micro-discharge results in the formation of a soot channel, which is empirically known to exhibit semiconductor behavior. Because of its capability to conduct electricity, the emerged soot channels harm the subsequent capacitor performance and decrease the amount of stored energy. The accumulation of the soot throughout a dielectric capacitor ultimately results in irreversible overall failure. In the context of the dielectric breakdown, self-healing designates a range of chemical processes, which spontaneously rearrange the atoms in the soot channels to partially return their insulative function. We developed a universal method capable of rating new capacitor designs including electrode and polymer material and their proportions. We found the best-performing designs produce abundant volatile by-products after micro-discharge, whereas the soot samples exhibit lower electronic conductivities. We proved the capability of the theoretical method to rate the empirical performance of the known capacitors. The method relies on various electronic-structure simulations and potential landscape explorations. The reported advance opens an impressive avenue to computationally probe thousands of hypothetical capacitor designs.

physics.app-ph↗

arXiv2024

Potential Energy Landscape as a Framework for Developing Innovative Materials

In the contemporary era of rapid advancements in materials science, the development of new compounds and materials is proceeding at an accelerated pace. The concept of the potential energy landscape (PEL) plays a pivotal role in supporting the meticulous engineering of novel structures. This review article examines the historical evolution of the PEL concept and its diverse applications in materials design. A comprehensive overview of the major methods employed to sample the PEL is presented, accompanied by a critical discussion highlighting relevant modern endeavors. Specific applications of the PEL in rationalizing the design of molecules and materials for energy storage, electrolytic solutions, and greenhouse gas capture are exemplified. This review serves as an up-to-date guide for exploring and analyzing the PEL, facilitating a deeper understanding of its significance in materials science.

cond-mat.mtrl-sci↗

arXiv2023

Revolutionary valorization of carbon dioxide into dimethyl carbonate is catalyzed by sodium chloride: cheap, clean, one-pot, and water-free synthesis

The robust valorization of carbon dioxide (CO2) stays at the center of sustainable development. Since CO2 represents a low-energy compound, its transformation into commercially coveted products is cumbersome. In the present work, we report a revolutionary method to obtain dimethyl carbonate (DMC) out of methanol (CH3OH) and CO2 catalyzed by sodium chloride (NaCl) and similar inorganic salts. The computational exploration revealed a mechanism of favorable catalysis, which was subsequently confirmed experimentally. Unlike all competitive syntheses of DMC, the new one does not produce water and, therefore, the hydrolysis of a carbonate does not occur. No dehydrating agents are necessary. The employed catalyst is cheap and permanently exists in the same phase with the reactants and products. The action of NaCl was compared to those of other alkali metal salts, LiI, LiCl, and KI, and competitive performances were recorded. The experimentally obtained result outperforms most competing technologies according to the DMC yield, 19% with molecular sieves and 17% without molecular sieves. All existing competitors are excelled by the simplicity and cleanness of the synthesis. The reported advance substantially simplifies the synthesis of linear organic carbonates and robustly valorizes CO2. Keywords: Dimethyl carbonate; carbon dioxide utilization; sodium chloride; methanol.

cond-mat.mtrl-sci↗

arXiv2023

The Trialkylsulfonium Cation Holds Promise to Capture Carbon Dioxide: In-Silico Evidence Toward a Novel Carbon Dioxide Scavenger

The concentration of carbon dioxide (CO2) in the Earth atmosphere is linked to the acute problem of global warming. For the first time, we herein introduce trialkylsulfonium aprotic ionic liquids (ILs) as a group of seemingly highly capacitive CO2 scavengers. We advocate the viability of the new sorbents by the reaction profiles recorded by means of hybrid density functional theory. All stages constituting CO2 chemisorption, such as the ethyldimethylsulfonium S211-cation deprotonation, S211-ylide carboxylation at the alpha-methylene group, and aprotic anion carboxamidation have been explored. The S211-ylide formation reaction is thermochemically forbidden but its cost is affordable. The energetic cost ranges from a tiny number of 14 kJ/mol for S211 indazolide to a mediocre value of 50 kJ/mol for S211 1,2,4-triazolide. The barriers corresponding to the sulfonium-based cation deprotonation range from 39 kJ/mol for benzimidazolide to +60 kJ/mol for 1,2,4-triazolide. The energy loss during the ylide intermediate formation is strongly compensated for by the subsequent sulfonium ylide carboxylation. The energetic gain is weakly dependent on the nature of the heterocyclic aprotic anion being 99 to 110 kJ/mol for different ionic species studied. The AHAs additionally participate in CO2 capture following the route of carboxamidation thanks to their nitrogen sites. The most thermochemically favorable carbamate forms out of S211-indazolide, 68 kJ/mol. The steric and covalent barriers associated with these reactions are of the order of thermal motion energy, whereas a specific chemical structure of AHA engenders marginal differences. The rationalization of the energy reaction profiles is given in terms of partial atomic charges, geometrical peculiarities, steric barriers, imaginary vibrational frequencies, and related descriptors.

physics.chem-ph↗

arXiv2022

Cathodic Carbon Chemically Adsorbs Carbon Dioxide: Why Is it True?

Large-scale applications are waiting for an optimal CO2 scavenger to reinforce CCS and CCU technologies. We herein introduce and succinctly validate a new philosophy of capturing gaseous CO2 by negatively-charged carbonaceous structures. The chemical absorption of CO2 turns out possible thanks to the emergence of significant nucleophilic interaction carbon centers upon applying voltage. The carbonaceous cathode, therefore, may serve as a prototype of a new CO2 sorbent. As a model to simulate chemisorption, we used a small-sized graphene quantum dot (GQD). According to the recorded reaction profiles, the negatively charged GQD containing 16 carbon atoms readily reacts with the CO2 molecule and produces carboxylated GQD. In turn, the activation energy (60 kJ/mol) and energy effect (-55 kJ/mol) for the reaction in water appeared surprisingly competitive in the context of the literature. We hypothesize that the carbonaceous cathode deserves in-depth experimental research as a possible CO2 chemical sorbent. Despite we used GQD for simulations, the encouraging results can be extrapolated to other nanoscale carbons and, more importantly, to the activated carbon species widely employed in modern electrochemical devices.

cond-mat.mtrl-sci↗

arXiv2022

On the Carbon Dioxide Capture by Quaternary Ammonium-Based and Phosphonium-Based Ionic Liquids. The Role of Steric Hindrances and Transition States

Global warming is seen as a drastic environmental problem nowadays. Carbon dioxide (CO 2 ) concentration in the Earth's atmosphere is linked to the average temperature on the surface of the planet. Carbon capture and storage is an important technological endeavor aiming to improve the ecology. The present work investigates reaction paths that are responsible for CO 2 chemisorption by the ammonium- and phosphonium-based ionic liquids containing an aprotic heterocyclic anion 2-cyanopyrrolidine. We show that two moles of CO 2 per one mole of the gas scavenger can be theoretically fixed by such ionic liquids. Both the cation and anion participate in the chemisorption. The corresponding standard enthalpies are moderately negative. The barriers of all reactions involving the phosphonium-based cation are relatively small and favor practical applications of the considered sorbents. The performance of the ammonium-based cation is less favorable due to the inherent instability of the tetraalkylammonium ylide. The role is phosphonium ylide in the mechanism of the reaction is carefully characterized. The reported results foster a fundamental understanding of the outstanding CO 2 sorption performance of the quaternary ammonium and phosphonium-based 2-cyanopyrrolidines.

physics.chem-ph↗

arXiv2022

The Affinity of the Sulfate- and Ether-Containing Surface-Active Ionic Liquids to Carbon Dioxide, Hydrogen Fluoride, Hydrogen Sulfide, and Water

The development of novel task-specific ionic liquids (ILs) represents an essential challenge in modern organic and physical chemistries. Recently we reported surface-active ILs contained the two well-known organic cations (1-butyl-3-methylimidazolium and tetrabutylammonium) and the two surface-active anions (lauryl sulfate, lauryl ether sulfate). In the present work, we investigate the affinity of these ionic compounds to the selected small molecules that exhibit practical implications: water, hydrogen fluoride, hydrogen sulfate, and carbon dioxide. We identified that the sulfate group, the ether groups, and the aromatic imidazole ring make the strongest contributions to the physical sorption of the polar gas molecules. In turn, the tetrabutylammonium cation, the saturated hydrocarbon chain of the anions, and the alkyl chains of 1-butyl-3-methylimidazolium contribute to a significantly smaller extent. The reported data are interesting in the context of using surface-active ILs in the oil industry to capture and store undesirable and toxic gases.

cond-mat.soft↗

arXiv2021

Mixtures of Diethyl Sulfoxide and Methanol: Structure and Thermodynamics

Mixtures of sulfoxides with molecular solvents possess interesting physical-chemical properties and may have applications in chemical synthesis. Hereby we confirm and rationalize the previously reported excellent miscibility of diethyl sulfoxide (DESO) with methanol (MeOH). By performing a comprehensive potential energy surface investigation we identified a global minimum for each system and a significant number of local minima described at the hybrid density functional level of theory. A strong 0.18-nm-long hydrogen bond forming between the oxygen atom of DESO and the polarized hydrogen atom of MeOH was evidenced both via the structural and spectral analyses. Our results robustly explain negative deviations in the DESO-MeOH mixtures from ideal behavior and interpret the experimental observations with microscopic precision.

cond-mat.mtrl-sci↗

arXiv2021

Ammonium-, Phosphonium- and Sulfonium-Based 2-Cyanopyrrolidines for Carbon Dioxide Fixation

The development of carbon dioxide (CO2) scavengers is an acute problem nowadays because of the global warming problem. Many groups around the globe intensively develop new greenhouse gas scavengers. Room-temperature ionic liquids (RTILs) are seen as a proper starting point to synthesize more environmentally friendly and high-performance sorbents. Aprotic heterocyclic anions (AHA) represent excellent agents for carbon capture and storage technologies. In the present work, we investigate RTILs in which both the weakly coordinating cation and AHA bind CO2. The ammonium-, phosphonium- and sulfonium-based 2-cyanopyrrolidines were investigated using the state-of-the-art method to describe the thermochemistry of the CO2 fixation reactions. The infrared spectra, electronic and structural properties were simulated at the hybrid density functional level of theory to characterize the reactants and products of the chemisorption reactions. We conclude that the proposed CO2 capturing mechanism is thermodynamically allowed and discuss the difference between different families of RTILs. Quite unusually, the intramolecular electrostatic attraction plays an essential role in stabilizing the zwitterionic products of the CO2 chemisorption. The difference of chemisorption performance between the families of RTILs is linked to sterical hindrances and nucleophilicities of the α- and \b{eta}-carbon atoms of the aprotic cations. Our results are supported by the previous experimental CO2 sorption measurements and systematically extend their scope.

physics.chem-ph↗

arXiv2021

Elimination of Interionic Hydrogen Bonding in the Imidazolium-Based Ionic Liquids

Hydrogen bonding is a phenomenon of paramount importance in room-temperature ionic liquids. The presence or absence of the hydrogen bond drastically alternates self-diffusion, shear viscosity, phase transition points, and other key properties of a pure substance. For certain applications, the presence of cation-anion hydrogen bonding is undesirable. In the present paper, we investigate perspectives of removing the hydrogen...fluorine interionic attraction in the imidazolium borates, the strongest non-covalent interaction in this type of system. Chemical modification of the tetrafluoroborate anion not only eliminates hydrogen bonding but also changes the most thermodynamically preferable orientation of the cation in the vicinity of the anion. Although the most acidic hydrogen atom of the imidazole ring remains the paramount electrophilic center of the cation, it does not engender a strong electrostatically driven coordination pattern with the properly modified anions. The reported new physical insights help compose more robust ionic liquids and tune solvation properties of the imidazolium-based RTILs.

cond-mat.soft↗

arXiv2021

Diethyl Sulfoxide as a Novel Neutral Ligand in the Platinum Complex Anion

Diethyl sulfoxide (DESO) is far less known than its shorter-alkyl-chain homolog, dimethyl sulfoxide. Although the field of senior dialkyl sulfoxides does not currently exhibit an explosive growth, new fundamental and applied research works routinely appear from a few research groups in the world. Recently, the tetraethylammonium diethylsulfoxidopentachloroplatinate complex compound was synthesized containing the DESO molecule as a neutral ligand. In the present paper, we use a systematic computational method to rationalize the mentioned synthetic achievement in coordination chemistry. We show that only up to two DESO molecules may exist in the platinum (IV) complex ion, whereas all higher contents of DESO are thermodynamically unstable and the sterical factor plays an important role in their instabilities. Structural analysis of the tetraethylammonium diethylsulfoxidopentachloroplatinate ion pair reveals its rather strong cation-anion coordination and for the first time explains an experimentally derived high melting point. The reported results are expected to inspire experimental efforts to extend the universe of senior sulfoxides as neutral organic ligands in d-metal complexes.

cond-mat.soft↗

arXiv2018

Binary Mixtures of Novel Sulfoxides and Water: Intermolecular Structure, Dynamic Properties, Thermodynamics, and Cluster Analysis

Senior dialkyl sulfoxides constitute interest in the context of biomedical sciences due to their abilities to penetrate phospholipid bilayers, dissolve drugs, and serve as cryoprotectants. Intermolecular interactions with water, a paramount component of the living cell, determine performance the sulfoxide-based artificial systems in their prospective applications. Herein, we simulated a wide composition range of the sulfoxide/water mixtures, up to 85 w/w% sulfoxide using classical molecular dynamics to determine structure, dynamics, and thermodynamics as a function of the mixture composition. As found, both diethyl sulfoxide (DESO) and ethyl methyl sulfoxide (EMSO) are strongly miscible with water. DESO and EMSO based aqueous mixtures exhibit similar structure and thermodynamic properties, however, quite different dynamic properties over an entire range of compositions. Strong deviations from an ideal mixture between 30 50 mol% of sulfoxide content leads to relatively high shear viscosities of the mixtures. Free energy of mixing with water is only slightly more favorable for EMSO than for DESO. The results, for the first time, quantify high miscibilities of both sulfoxides with water and motivate comprehensive in vivo investigation of the proposed mixtures.

cond-mat.soft↗

arXiv2017

Hydration Peculiarities of Graphene Oxides with Multiple Oxidation Degrees

Hydration properties of graphene oxide (GO) are essential for most of its potential applications. In this work, we employ atomistic molecular dynamics simulations to investigate seven GO compositions with different levels of oxygenation. Two atomic charge models for GO are compared: (1) sp2 carbons are purely Lennard-Jones sites; (2) sp2 carbon charges are consistent with the CHELPG scheme. Structural properties were found to depend insignificantly on the charge model, whereas thermodynamics appeared very sensitive. In particular, the simplified model provides systematically stronger GO/water coupling, as compared to the more accurate model. For all GO compositions, hydration free energies are in the range -5 to -45 kJ mol-1 indicating that hydration is thermodynamically favorable even for modest oxidation degrees, thus differing drastically from the case of pristine graphene and graphite. The results and discussion presented hereby provide a physical background for modern applications of GO, e.g. in electrodes of supercapacitors and inhibitors in processes involving biological molecules.

cond-mat.mtrl-sci↗