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Keywords: electron microscopy

Structural and morphological characteristics of layered hydroaluminosilicates activated by solutions of alkali metal chlorides

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 38-49 p.
Abstract
This study presents the results of a comparative investigation into the chemical and mineralogical compositions, as well as the structural-morphological characteristics of enriched and modified forms of clay, which contains layered hydroaluminosilicate – montmorillonite – as its main mineral phase. Impurity minerals in the clay raw material include kaolinite, low-temperature trigonal quartz, calcite, and illite, whose presence is confirmed by transmission electron microscopy and infrared Fourier spectrometry. Activation of the enriched rock was performed by treating it with solutions of alkali metal chlorides – lithium, potassium, and sodium chlorides. It is shown that the original form of the clay does not contain Na2O and Li2O oxides. However, through the salt treatment of the enriched hydroaluminosilicate rock, products with a content of lithium, sodium, and potassium oxides were obtained, amounting to 1.96%, 3.98%, and 6.28% by mass, respectively. It is established that the treatment with potassium chloride solution has the most significant influence on the structural-morphological characteristics of montmorillonite clay. Specifically, the sample treated with KCl solution exhibits an increased tendency towards particle aggregation and the formation of relatively large, spherical grains. It is also shown that the activated product mentioned above is almost entirely devoid of the mineral phase known as calcite. Meanwhile, the impact of LiCl and NaCl salt solutions on the enriched clay raw material hardly alters the microstructure of the resulting products.
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FORMATION OF NANOCOMPOSITE CARBON MATERIALS WITH BIMETALLIC NANOPARTICLES FOR AUTONOMOUS ENERGY SOURCES

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 5-12 p.
Abstract
The development of highly efficient autonomous energy sources allows for stable and uninterrupted power supply of physical and chemical processes and industries under various operating modes. Modern technological methods and approaches to the production of nanostructured electrode materials, as well as the elucidation of the features of the mechanisms of electrochemical reactions based on platinum metal nanoparticles make it possible to design control sensors, fuel cells and electrolyzers with increased energy characteristics. Carbon nanotubes used to create nanostructured electrodes in chemical energy converters have high functional properties compared to other matrices and, modified with nanoparticles with a reduced metal content, can increase the electrocatalytically active electrode surface area and achieve maximum fuel cell power parameters. In this work, the formation of bimetallic nanostructured composites with a variable composition on carbon carrier matrices for the construction of electrodes of autonomous current sources was carried out. Single- and multi-wall carbon nanotubes were chosen as substrates. To obtain composites, bimetallic platinum-palladium nanoparticles with different metal ratios were synthesized. The materials were studied by electron microscopy and X-ray phase analysis. As a result, an optimal algorithm, a synthesis method and conditions for creating nanocomposites with minimal particle sizes are established. The molar ratio water:surfactant changing, as well as the ratio of precursor metals, it is possible to obtain bimetallic platinum-palladium nanoparticles up to 12 nm. The data on the influence of the formation metal nanoparticles conditions on their size, shape and distribution over the matrix surface had been obtained. A series of prototypes has been formed for practical use in the design of current sources.
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MINERALOGICAL COMPOSITION OF CLAYS OF THE «POLYANA» FIELD AS POTENTIAL SORPTION-ACTIVE MATERIALS OF INORGANIC ORIGIN

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 67-76 p.
Abstract
This work presents the results of a study of the phase (mineralogical) composition of clay from the Polyana field, Shebekinsky district, Belgorod region. To study the morphological and structural features of the mineral components that make up the specified clay, a set of methods of scanning and transmission microscopy, electron microdiffraction and energy dispersive analysis were used. Electron microscopic examination of Polyanskaya clay showed that it is composed of such minerals as: calcium and magnesium-iron form of montmorillonite, muscovite, low-temperature trigonal quartz, illite and ruthyl. More often than others, the preparations contain particles identified as montmorillonite, differing in structure without shaped edges and having a layered structure (layer thickness of about 1 nm). Particles of this mineral show a high tendency to aggregation, but at the same time they are quite easily split along the cleavage plane during dispersion, and therefore have a developed specific surface area, which determines good sorption characteristics.
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PHYSICO-CHEMICAL FEATURES OF THE PALLADIUM NANOCATALYSTS FORMATION ON COMBINED MATRICES-CARRIER FOR FUEL CELLS

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 58-66 p.
Abstract
The development of modern nanotechnological methods and approaches to the synthesis and formation of nanostructures allows us to create new materials that combine various functional properties and unique physical and chemical characteristics. Such structures include composite materials consisting of a structured matrix modified with various fillers. Currently, composites are of particular interest to researchers, in which nanoscale particles play the role of filler, which makes it possible to obtain catalysts with increased activity and stability. Commercial perfluorinated proton exchange membranes of the Nafion type and carbon-containing carriers (carbon nanotubes, graphene, fullerenes) are promising carrier matrices for chemical energy sources – fuel cells. Nanoparticles based on platinum, palladium, or their alloys are excellent materials for the reactions of electrocatalytic oxidation of hydrogen and oxygen reduction that occur in fuel cells. The elements based on the direct oxidation of formic acid mainly use bimetallic nanoparticles based on palladium, which exhibit higher catalytic properties. In this work, new effective polymer-carbon composites modified with palladium nanoparticles were synthesized. Single- and multi-wall carbon nanotubes were chosen as substrates. Physicochemical studies of the obtained materials were carried out using electron microscopy and small-angle X-ray light scattering. The sizes of nanoparticles in the composition of functional carrier matrices are determined. It was found that the carbon filler contributes to the better stabilization of small nanoparticles in the composition of the composite. The data on the influence of the conditions for the formation of metal nanoparticles on their size, shape and distribution over the matrix surface are obtained. The stability of samples with variable palladium loading on various carrier matrices was studied by chronoamperometry. The prospects of using the formed materials for fuel cell electrodes with direct oxidation of formic acid are proved.
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