This study investigates deposition of a pyrolytic carbon layer onto spheroidized graphite particles by microwave irradiation, combining computational modeling with experimental validation. Computational fluid dynamics and heat transfer simulations were performed to analyze gas flow dynamics and temperature distribution above the sample surface, enabling optimization of gas flow rates to avoid stagnant zones and improve uniformity of carbon deposition. Electromagnetic simulations identified the optimal packing geometry for achieving most uniform current density distribution. Experimental modification was performed in a microwave-integrated reactor using an Ar-ethylene/methane gas mixture as the carbon precursor, and results confirmed the computational predictions. Microwave-assisted modification enabled carbon deposition times ranging from 10 min down to 3 s, avoided energy-intensive side heating, and enhanced electrochemical performance. The modification increased reversible capacity from 362 mAh g-1 to 399 mAh g-1 and improved coulombic efficiency from 76% to 87% in the first cycle. The proposed method offers a rapid, efficient approach to improve graphite anodes for high-performance lithium-ion batteries.

Experimental investigation of the relationship between activation and performance was done using a Co-catalyzed Fischer-Tropsch synthesis as a model. This research was aimed at obtaining clarification for two important problems: (1) Can the degree of reduction of the active metal deposited on a multicomponent support be treated as an additive value. (2) Is a high degree of Co reduction necessary for achieving high performance? The Co reduction degree was measured both for each component of a complex support and for a whole catalyst. We found that the Co reduction degree is never additive but determined by the most difficult-to-reduce component and depends primarily on binder properties. It was also shown experimentally that the active Co centers continue to change their reduction degree in the course of Fischer-Tropsch synthesis. Thus, the relationship between the activation and performance of catalysts turned out to be more complicated and important for synthetic fuel processes.

This work focuses on investigating carbon materials as anodes for sodium-ion batteries, specifically utilizing a non-graphitizable carbon material based on the phenol-formaldehyde resin with varying concentrations of aniline and thiophene as heteroatoms. Four series of experiments were conducted to synthesize anode materials based on a simple phenol-formaldehyde resin precursor. Four different phenol-formaldehyde resin to aniline weight ratios were applied, namely 0:1, 1:1, 9:1, and 3:1. In the case of thiophene there were three samples and the molar ratios of reagents were as follows: 1:1, 9:1, 99:1. This study aims to provide insights into the electrochemical behavior of these novel anode materials, shedding light on the impact of aniline incorporation into phenol-formaldehyde resins for sodium-ion battery applications.

This paper describes various compositions of electrically conductive pastes based on polyvinyl chloride, which are suitable for screen printing technology. These pastes are composite systems consisting of finely dispersed particles of a conductive filler, specifically various carbon modifications. These carbon particles are uniformly dispersed within a polymer binder. Electrically conductive carbon pastes therefore consist of three main components: the conductive carbon filler, the polymer binder, and a solvent. Other modifying or stabilizing additives can also be used in the paste, depending on the specific application. The paper investigates the optimal ratio of these componentsAin pastes, specifically between the selected polymer binder (polyvinyl chloride) and the total amount of carbon fillers (graphite and carbon black). This allows to obtaine relatively high-quality electrodes with low electrical resistance. To further search of the minimum possible electrical resistivity value at the selected polyvinyl chloride concentration, an additional set of experiments was conducted with varying ratios of both carbon fillers. The results of a comparative analysis of the surface of the manufactured electrodes using scanning electron microscopy are presented, showing the difference in coating quality based on the composition. It is demonstrated that, in order to meet the required objectives, it is possible to produce electrically conductive carbon pastes with specific properties. Factors that lead to defects affecting both the screen printing process and final printed products are discussed. A unique graph illustrating the correlation between the possibility of screen printing the developed electrically conductive carbon paste and the final electrical resistivity values of the electrodes based on them is provided.

One of the most popular technologies for electrical energy storage currently remains lithium-ion batteries (LIB), in which various carbon materials can act as the active anode material, in particular natural graphite, characterized by stable electrochemical characteristics during repeated cycling of charging/discharging processes. The paper discusses the use of gas chromatography to optimize the conditions for the pyrolytic deposition of hydrocarbons onto modified (spheroidized) natural graphite, which is carried out to significantly improve the Coulomb efficiency of these carbon materials when used in LIBs. It was shown that the analysis of gases released from the pyrolysis reactor by gas chromatography makes it possible to choose carbon-containing precursors and the conditions of their pyrolytic heterophase decomposition for the formation of a uniform film of pyrolytic carbon on the surface of modified (spherolized) natural graphite. The using of gas chromatography in the analysis of released gases also makes it possible to minimize the processes of homophase pyrolytic decomposition of a carbon-containing precursor, leading to the formation of separate carbon phases, which can be characterized by extremely low values of reversible capacity for lithium. Analysis of the ratios of product concentrations during pyrolysis allows us to conclude that the pyrolysis mechanism remains unchanged throughout the entire duration of the process. It was shown that the profile of changes in the hydrogen content in the gas mixture coming from the reactor of the pyrolytic decomposition of carbon-containing precursors correlates with the trend of changes in the specific surface area of spheroidized graphite samples. The results obtained suggest that in the case of the unchanged mechanism of pyrolytic decomposition of a carbon-containing precursor, its unchanging concentration and the heterophasic nature of pyrodecomposition, analysis of the profile of changes in the hydrogen content emanating from the reactor can be used to select optimal conditions for pyrodeposition. For example, it can be used to select the pyrolysis duration necessary to saturate structural defects in the graphite matrix, the presence of which can lead to high irreversible capacity during the first cycles of lithium interclaring and deintercalation.

Experimental results of investigation of the original and fluorinated ultra-long double- walled carbon nanotubes (DWCNTs) with a length of at least 1000 mu m are presented. The degree of fluoridation did not exceed 27 at.%. It has been shown that the process of fluorination of samples of double-walled carbon nanotubes deforms the outer surface of the nanotube wall although does not destroy its internal concentric structure, while the diameter of the fluorinated nanotube increases by 1.5-2 times. In addition, the fluorinated samples, which were thermochemically purified from iron particles and other forms of carbon before fluorination, demonstrated many split/cut ends of nanotubes. The effect of fluorination on the electrical properties of initial and purified samples of double-walled carbon nanotubes was studied. It was revealed that with an increase in temperature from 80 to 300 K for non-fluorinated and fluorinated purified nanotube samples, the resistivity decreases, which corresponds to the semiconductor nature of the conductivity. It was also revealed that when a sample of initial DWNT is fluorinated, a change in the nature of conductivity from semiconductor to metallic is observed. With an increase in temperature from 80 to 300 K, the resistance of the non-fluorinated sample of the original DWNTs decreased by 45%, while the resistance of the fluorinated sample increased by 11%. Despite the decrease in electrical conductivity as a result of fluorination of the purified samples, all samples remained conductors, which presumably indicates partial fluorination of the outer wall of the DWNTs while maintaining the structure of the inner wall. Thus, fluorination of double-walled carbon nanotubes with a well-aligned and concentric structure leads to the formation of fluorocarbon nanostructures, which can be promising materials for electronic nanodevices.

This work is devoted to the development of anode material for sodium-ion batteries. Nongraphitizable carbon as known as hard carbon is most often used as such a material in research, since, unlike the situation with the problematic intercalation of sodium ions into graphite, here they can intercalate into pseudographitic domains and be reversibly adsorbed on surface edges, defects and nano-sized pores. In this research, samples of material for the anodes of sodium-ion batteries based on hard carbon obtained by carbonization under different conditions of a resol-type phenol-formaldehyde resin with a molar ratio of reagents of 1:1 were prepared and studied. Two series of experiments were carried out on the synthesis ofAten anode materials: in which the effect of carbonization temperature (1000/1100/1200/1400 degrees C) and the effect of exposure time at a temperature of 1100 degrees C (30/60/90/120/180/240 min) were studied. All obtained materials are subjected to grinding and sifting to obtain a powder with a particle size of no more than 80 mu m. The manufactured materials were studied by transmission electron microscopy, scanning electron microscopy and Raman spectroscopy. AsAa result of electrochemical measurements, it was found that the carbonization temperature of phenol-formaldehyde resin greatly affects the discharge capacity of the final material, which increases to 311 mAh/g in the first cycle when moving from 1000 to 1100 degrees C and then decreases. On the other hand, the dependence of capacity on exposure time is also not monotonic and has a certain optimum around 180 min. In all cases, the Coulombic efficiency in the first cycle varies from 70 to 85% and exceeds 80% for the sample held for 180 min at the temperature of 1100 degrees C.

The activation stage of high-performance cobalt catalysts for Fischer–Tropsch synthesis has been studied, taking into account the transformation of emerging structures and the presence of a percolation heat-conducting network of metallic aluminum. The influence of temperature, process duration, composition of the reducing gas, as well as its volumetric velocity on the degree of reduction and surface area of the active component of the catalyst was studied. These characteristics were determined by low- and high-temperature oxygen titration in a chromatographic-type sorption unit, as well as using temperature-programmed reduction. The possibility of reducing the temperature and concentration of hydrogen in the gas to achieve the required parameters during reduction to obtain a high-performance catalytic system has been experimentally demonstrated. Its performance in Fischer–Tropsch synthesis (CO conversion, liquid hydrocarbon productivity) is comparable or better than that achieved on a catalyst reduced under standard conditions.

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Structured Fischer–Tropsch synthesis catalysts were tested in tubular reactors of industry-standard diameters of 0.5 or 0.75 inches. The structured catalyst bed was manufactured by the obturation of a straight bunch of graphite-based extrudates (D = 1.5 mm, L = 30 mm). A conventional loose bed of granulated catalyst (D = 1.5 mm, L = 3 mm) was tested as a reference. In a 1000–3000 h−1 syngas space velocity range, structured and loose catalyst bed testing showed no significant differences in their main catalytic parameters. Nevertheless, their C5+ hydrocarbon group composition was quite different, i.e., the alkene fraction rose from 9 to 23%, while n-alkanes dropped from 81 to 64%. This could be a result of secondary reaction intensification in the conventional loose bed due to its zeolite acid site’s higher availability. Further FTS testing of the structured catalysts in 4000–6000 h−1 manifested distinctive limits in C5+ productivity for 0.5 and 0.75 inches of 512 kg C5+/(m3 reactor·h) and 362 kg C5+/(m3 reactor·h), respectively. This may be explained by limitations in structured bed thermal conductivity. It suggests that the arrangement of extrudates in the structured catalyst can significantly affect the reaction heat and mass transfer conditions and affords new opportunities for group composition control by means of catalyst bed organization.

It is shown that acid activation of ultralong carbon nanotubes synthesis products increases their reactivity during subsequent thermochemical treatment in air at 480 degrees C. Such an integrated approach of CNTs processing provides high purity and maximum yield of the target product. For example, the non-CNT fraction decreases by 3.2 times, while the residual iron content decreases by 17-24 times in comparison with thermochemical treatment without acid. Raman spectroscopy and low-temperature nitrogen adsorption showed that acid activation does not lead to extra surface defects, which could initiate further oxidation of carbon matrix in air. It is suggested that the increased reactivity of CNT synthesis products after acid activation during thermo-oxidative degradation may be due to the formation of an "adduct" of carboxyl groups on the surface of nanotube carbon matrix with hydrogen chloride. It was shown by thermogravimetric studies coupled with mass-spectra investigation of gas evolved, that under the constant heating, at the temperatures of the beginning of intensive oxidation (500-600 degrees C), the decomposition of the "adduct" occurs, bypassing the stage of formation of more temperature-resistant phenolic groups, which can inhibit further oxidation. Water released during the decomposition of the "adduct" can also accelerate the process of thermal oxidation.

The possibility of the use of commercially available silica-alumina hydrate Siral-40, containing 40 wt.% of SiO2, in the composition of a composite cobalt Fischer-Tropsch - Tropsch synthesis (FTS) catalyst was studied. The use of silica aluminas may become aAnew promising direction in the development of catalysts forAa shortened technological chain based on the use of bifunctional catalysts that make it possible to eliminate the hydroprocessing stage. In addition, such catalysts can be useful for expanding the range of products obtained, including those unconventional for singlereactor Fischer-Tropsch synthesis. The initial silica alumina powder was pretreated in air flow at different temperatures to adjust the concentration of acid cites on its surface. The initial and calcined powders were studied using X-ray diffraction analysis, IR spectroscopy and sorption methods. The catalysts were investigated by diffraction and sorption methods. It has been shown that an increase in the calcination temperature of the initial Siral-40 powder leads to a decrease in the specific surface area and pore volume of catalysts based on it, with temperatures above 900 degrees C having the greatest effect. The synthesized catalysts were active in FTS, and the composition of the obtained C5+ hydrocarbons depended more on the properties of the Siral-40 powder than the catalytic performance. The composition of C5+ hydrocarbons, obtained in the presence of all investigated catalysts contained at least 60% of diesel fraction and more than 30% of wide base oil fraction. Thus, synthetic amorphous silica aluminas areAa promising component for new Fischer-Tropsch synthesis catalysts, which make it possible to obtain a wide range of products without the use of a deep hydroprocessing stage in the technological chain.

The intensive development of electric vehicles and portable electronics significantly activated the research in the field of electric batteries, in particular, lithium-ion batteries (LIB) and their components such as electrodes. The application of differential thermogravimetric analysis and differential scanning calorimetry under oxidative atmosphere for quantitate determination of pyrolytic carbon in the products of heterophase decomposition of toluene-argon mixture on the spheroidized graphite, which is used as the active materials of the LIA anodes, is regarded. It was shown, that the using of double mass loss at the maximum combustion rate of pyrolytic graphite under the heating rate of 10 degrees C/min makes it possible to determine the content of pyrocarbon in the range from 8 to 23 wt.% with the precision of not less than 10%. The local extremums on the curves of either differential thermogravimetric analysis or differential scanning analysis can be chosen as the maximum combustion rate of pyrolytic carbon. It was established that further increasing of precision can be achieved by decreasing of heating rate which causes, however, increasing of the measurement duration. The using of heating rates higher than 10 degrees C/min can result in significant overlapping of thermooxidative destruction processes of pyrolytic carbon and spheroidized graphite, that can lead to increasing in an error and to appearance of difficulties under determination of maximal combustion rate of pyrolytic carbon. It was noted that such an approach can cause significant error if the properties of pyrolytic carbon coating are similar to those of spheroidized graphite.

Уважаемые коллеги!Благодарим Вас за проявленный интерес к Четвертой российской конференции «Графен: молекула и 2D кристалл» и желание принять участие в её работе.Конференция проходит в научно-образовательном центре города Новосибирска -Академгородке.Мероприятие посвящено актуальным направлениям исследований и разработок в области углеродных и низкоразмерных материалов.Проведение конференции поможет координации усилий ученых в решении современных проблем материаловедения и привлечению молодых исследователей для решения актуальных научных задач.Оргкомитет выражает особую благодарность НГУ, Центру компетенций НТИ «Моделирование и разработка новых функциональных материалов с заданными свойствами», компаниям «Диаэм», «НТ-МДТ Спектрум Инструментс» и корпорации "Графеновая Долина" за финансовую поддержку и журналам Аналитика, Наноиндустрия и РЭНСИТ за информационную поддержку.Искренне надеемся, что пребывание в Новосибирском Академгородке и в стенах Новосибирского государственного университета оставит множество положительных эмоций и

There is a demand for new affordable and inexpensive batteries, such as those based on sodium, but sodium-ion battery (NIB) technology is still in its early stages of development. The development of high-performance anodes and a full understanding of sodium storage mechanisms are the main issues that need to be solved. Lithium (LIB) and sodium ion batteries (NIB) have similar components and a similar electrochemical principle of operation. Graphite, the most common anode material used in commercial LIBs, exhibits poor electrochemical performance when used in NIBs. For NIBs, non-graphitic carbon is widely used as an anode material, since sodium ions can intercalate into pseudographitic domains and be reversibly adsorbed on surface edges, defects, and nanosized pores. In the present work, hybrid carbon materials based on the non-graphitizable phenol-formaldehyde resin with graphite-containing additives such as colloidal graphite (CG) and graphene modified with phenol-formaldehyde groups (GMF) were prepared and investigated as anodes for sodium-ion batteries. On the basis of the FF11 precursor, two series of experiments were carried out on the synthesis of 3 anode materials with the addition of 0.2; 1 and 5 wt. % graphite additives of the carbon mass in the resin. The fabricated materials were studied by transmission electron microscopy, scanning electron microscopy, and Raman spectroscopy. As a result of electrochemical measurements, it was established that the presence of CG additives in the FF11 anode material does not lead to a significant change in the shape of the charge-discharge curve and discharge capacity, however, it significantly improves the material cyclability: the Coulombic efficiency of the charge-discharge cycle in this case reaches 99.8-99.9% at 250 mAh/g discharge capacity. On the opposite, the introduction of GMF additives into the anode material leads to a significant increase in capacity, which reaches 293 mAh/g at an additive content of 5%, while the Coulombic efficiency remains at the level of 96.5-98.5%. It is shown that all investigated anode materials are characterized by high cyclic stability.

An Erratum to this paper has been published: https://doi.org/10.1134/S2070050423030121

Continuous glucose monitoring (CGM) is considered to be the most advanced system for the minimally invasive blood sugar control. The working electrode of the CGM sensor should possess a number of properties such as flexibility to ensure the safety of an insertion under the skin, analytic signal stability, resistance to temperature, pH of the surrounding medium, humidity and mechanical stress (the friction against clothing when wearing or accidental impact). Enzymatic sensors, which are part of the vast majority of modern glucose meters, are affected by all the above impacts during both the operation and storage, because of the glucose oxidase enzyme that is the main constituent of the electrode of the sensor. In that regard the development of the enzyme-free electrode for glucose oxidation is still a contemporary task until now. This work is devoted to the fabrication of a flexible carbon electrode based on electrolytic manganese dioxide for enzyme-free glucose oxidation and to the determination of the activity dependence on the deposition potential of manganese dioxide on a flexible graphite foil (GF) from the MnSO4 solution. As a result of this study, the electrolytic MnO2 was shown to act as an enzyme-free electrocatalyst for glucose oxidation, and the deposition potential of the manganese dioxide on a graphite electrode was found to affect appreciably on its activity. It is shown that manganese dioxide obtained under low deposition rate possesses the highest activity, and the flexible graphite electrode based on it demonstrates a wide linear range (1-30 mM) of the dependence of the oxidation current on the square root of the glucose concentration. The sensitivity of the electrode was found to be 11.4 and 22.3 mu A/(cm(2).mM(0.5)) at 25 and 36degree celsius, respectively, which indicates that the sensor not only does not fail when the temperature rises, but also becomes twice as sensitive under conditions close to the real practical application.

A method for leaching Co2Al9 alloy was developed and optimized to produce nonpyrophoric Raney cobalt, which is used as a component of a highly efficient granular Fischer-Tropsch synthesis catalyst. A comparative study of the laboratory-produced Raney cobalt with commercially available analog was done using the methods of low-temperature nitrogen sorption, thermoprogrammed reduction (TPR), thermoprogrammed ammonia desorption, thermal analysis, thermal conductivity, and scanning and transmission electron microscopy. Partial dissolution of cobalt with the formation of Co2+ and Co3+ ions was detected during aluminum leaching. It was found that incomplete purification of commercial Raney cobalt from aluminum hydroxide impurity may lead to overestimation of specific surface area. It was also found that the acidity of the molded catalyst is mainly determined not by Raney cobalt, but by elements of the composite catalyst carrier. For the first time, a linear dependence between the content of structures in a Fischer-Tropsch synthesis catalyst with TPR-AR maxima of 500-800 degrees C and the amount of synthesized liquid hydrocarbons has been established. It is concluded that metal nanoparticles with partial charge transfer (Co delta+) are active centers of selective formation of C5+ hydrocarbons. Obtaining the maximum number of these centers and reaching a high thermal conductivity of the composite with a developed system of transport pores is a criterion for creating an effective cobalt catalyst for low-temperature synthesis of hydrocarbons.

Fischer-Tropsch synthesis, which is accompanied by the release of a significant amount of heat, inevitably imposes strict requirements on heat and mass transfer in the catalyst bed to ensure high productivity and selectivity for C5+ hydrocarbons. In this work, various types of aluminum metal powder were used as a heat-conducting additive, which were introduced into the composition of granular composite cobalt-zeolite catalyst. The influence of the aluminum metal powder particle size on some physicochemical characteristics of the composite, the main catalytic parameters and the composition of the formed C5+ hydrocarbons was studied. Synthesized and investigated Fischer- Trop sch synthesis catalysts, containing aluminum metal powder as a heat-conducting additive, which differs in shape and particle size, exhibited different catalytic activity in the formation of C5+ hydrocarbons and differed in the composition of the obtained products. It has been established that the particle size of the initial powder of heat-conducting additive determines the heat-conducting properties of the synthesized composite: the larger the particle size of the initial aluminum metal powder, the higher the thermal conductivity of the formed support. This, in turn, determined the productivity of the composite in the synthesis of C5+ hydrocarbons from CO and H-2. The porous system depended primarily on the shape of the particles (sphere or flake) and the manufacturer of the aluminum metal powder. The selectivity of the catalyst and the composition of the synthesis products, apparently, depended on the method of preparation and the chemical composition of the aluminum powder to a greater extent than on their size. The most selective in the formation of liquid hydrocarbons was catalyst containing aluminum metal flakes PAP-2 manufactured by RUSAL. It also had rather high C5+ hydrocarbons productivity, which makes it the most promising for further use due to its cost and availability on the Russian market.

A comparative analysis of industrial zeolite-containing cobalt catalysts for Fischer-Tropsch synthesis with a number of physicochemical parameters is performed. Catalysts containing a heat-conducting additive (aluminum flakes or exfoliated graphite) were tested in an industrial size single-tube reactor (length—6000 mm, inner diameter—12 mm). The testing results of a sample without heat-conducting additive are presented for comparison. It is shown that a catalyst based on support, containing exfoliated graphite is preferable for industrial application at high gas hour space velocities of the syngas due to its higher thermal stability and liquid hydrocarbon productivity.