Gold, nickel and platinum nanoparticles were synthesized by impregnating the monocrystalline silicon surface with precursors (an aqueous solution of the corresponding salt). The morphology of formed nanostructured coatings has been studied, the electronic structure and adsorption properties of synthesized nanoparticles with respect to H2, O2, and H2O have been determined. It was found that oxidized nickel nanoparticles are reduced by molecular hydrogen, and unalloyed platinum nanoparticles are oxidized by molecular oxygen already at room temperature, which is not observed for particles deposited in a similar way on highly oriented pyrolytic graphite. We also found that the formation of water molecules on gold nanoparticles in interaction with H2 and O2 proceeds in two stages, unlike the three-stage process (sequential exposure in H2, O2, H2) which is characteristic of nanoparticles deposited on graphite. Differences in the adsorption properties of nanoparticles of the same type deposited on graphite and silicon are associated with the adsorption of a significant amount of test gases on the latter.

Gold, nickel and platinum nanoparticles (NPs) have been synthesized by impregnating single-crystalline silicon surface with precursors (aqueous solutions of corresponding salts). The morphologies of the formed nanostructured coatings have been studied, and the electronic structures of the synthesized NPs, as well as their adsorption properties with respect to H2, O2, and H2O, have been determined. It has been found that oxidized nickel NPs are reduced by molecular hydrogen, while pure platinum NPs are oxidized by molecular oxygen already at room temperature. This phenomenon has not been observed for particles deposited in a similar way onto highly oriented pyrolytic graphite. In addition, it has been revealed that water molecules are formed on gold NPs as a result of the interaction between H2 and O2 in two stages, in contrast to the three-stage process (sequential exposure in H2, O2, and H2), which is inherent in NPs deposited onto graphite. Differences in the adsorption properties of NPs of the same type deposited onto graphite and silicon are associated with the adsorption of a significant amount of the test gases on the latter.

The process of hydrolysis of amide groups of polyacrylamide in the presence of a dispersion of nanosized copper particles obtained via the reduction of copper cations with sodium tetraborate has been studied. Quantum-chemical simulations have shown an increase in the effective positive charge on the carbon atom in the amide group upon formation of the complex with copper. Energy of interaction of units of polyacrylamide and polyacrylic acid macromolecules with a unit area of copper nanoparticles has been calculated. The significant difference in the energies leads to replacement of the hydrolyzed amide groups of the polymer from the surface of copper particles by the unreacted amide groups. The degree of hydrolysis of polyacrylamide in the presence of copper particles has been 89%, being 22% in the absence of the particles.

Процессы взаимодействия газообразных реагентов с образованными из наночастиц металлов покрытиями, нанесенными на пиролитический графит, исследованы методами сканирующей туннельной микроскопии и спектроскопии. Показано, что физические и химические свойства области контакта наночастиц с подложкой и области наиболее удаленной от нее могут различаться. Одной из причин наблюдаемых эффектов является перенос электрического заряда между наночастицами и подложкой. The processes of interaction of gaseous reagents with coatings formed from metal nanoparticles deposited on pyrolytic graphite have been studied by scanning tunneling microscopy and spectroscopy. It is shown that the physical and chemical properties of the area of contact of nanoparticles with the substrate and the area furthest from the first one may differ. One of the reasons for the observed effects is the transfer of electric charge between the nanoparticles and the substrate.

Проведено квантово-химическое моделирование адсорбции водорода на золотых и медных наночастицах на графите в рамках теории функционала плотности (DFT), в результате которого рассчитаны энергии связи металлических кластеров на графите с различными дефектами с атомарным водородом и изучено изменение плотности состояний атомов металлов при взаимодействии с этим адатомом. Для золота было выявлено большее уменьшение плотности состояний на границе металл-графит, для меди тенденций обнаружено не было. Все приведенные выше выводы согласуются с результатами экспериментальных исследований. Quantum-chemical modeling of hydrogen adsorption on gold and copper nanoparticles on graphite was conducted within the framework of density functional theory (DFT). As a result, bonding energies of atomic hydrogen with metal clusters on graphite with various defects were calculated, and the change in the density of states of metal atoms during interaction with this adatom was studied. For gold, a greater decrease in the density of states at the metal-graphite interface was observed, while no trends were found for copper. All the above conclusions are consistent with the results of experimental studies.

The patterns of clay modification with the addition of nickel formate and the composition of polystyrene sulfonic acid with nickel formate were studied. The addition of nickel formate alone resulted in the formation of pores in the mass and on the surface of the clay, which was filled with particles containing nickel. The introduction of polystyrene sulfonic acid into the composition led to the formation of a larger number of pores on the surface of the clay and the formation of nickel-containing particles with a more developed surface.

— A nanostructured gold–nickel coating has been synthesized on the surface of pyrolytic graphite. Its physicochemical properties have been studied by scanning tunneling microscopy and spectroscopy, Auger spectroscopy, mass spectrometry, and other methods. It has been found that the coating consists of clusters formed by gold and nickel nanoparticles. It has been shown that an electric field can inhibit or stimulate the adsorption of hydrogen on gold and the reduction of the oxidized surface of nickel nanoparticles with carbon monoxide. The mechanisms of the influence of the field on the chemical processes involving H 2 and CO are different. Quantum-chemical simulation has made it possible to determine the values of the energy barriers for CO adsorption on nickel nanoparticles.

The process of complex formation between polyethylenimine and copper cations in an aqueous solution, followed by isolation of copper nanoparticles, has been studied by means of ESR spectroscopy. It has been shown that in excess of the polymer in the solution the copper cation forms complex containing three nitrogen atoms in the coordination sphere, with distorted tetragonal geometry. The increase in copper concentration has led to the formation of the copper cation complex with water. Addition of the reducing agent NaBH 4 to the studied solutions has led to the formation of copper nanoparticles accompanied by gradual disappearance of the ESR signal of Cu(II) and the appearance of the ESR signal typical of the mononuclear copper complexes with polyethylenimine.

The influence of the ionic strength of the solution on the maximum degree of ionization of the imine groups of polyethylenimine during its interaction with hydrochloric acid was studied. It has been established that the ionic strength of the solution has a significant effect on the maximum degree of ionization of the polyethyleneimine. At a NaCl concentration of 1 mol/l, the maximum degree of ionization increases by 1.5 times.

Using the pH-metric titration method, the degree of deacylation of chitosan was determined to be 100 % and the degree of acylation of pectin was 20 % and their characteristic dissociation constants were 5.94 and 5.10, respectively. It has been shown that the solubility threshold of chitosan CS5 corresponds to the degree of ionization of amino groups equal to 22 %. It has been established that the dissociation constant of chitosan increases with increasing degree of dissociation, while for pectin it does not depend on the degree of dissociation.

Методом ЭПР-спектроскопии исследован процесс компексообразования полиэтиленимина с катионами меди в водном растворе с последующим выделением наночастиц меди. Показано, что в избытке полимера в растворе катион меди образует комплекс с тремя атомами азота в координационной сфере и искаженной тетрагональной геометрией. При увеличении концентрации меди начинает формироваться комплекс катиона меди с водой. Добавление в исследованные растворы восстановителя NaBH 4 приводит к образованию частиц Cu(0), вызывает постепенное исчезновение ЭПР-сигнала Cu(II) и возникает сигнал ЭПР, характерный для моноядерных комплексов меди с полиэтиленимином.

— Heterogeneous catalytic reactions involving nitrous oxide (N 2 O) are of great interest for medicine, technology, and ecology. The goal of this work is to determine the features of adsorption of N 2 O molecules followed by their interaction with a catalytic system based on metal nanoparticles at room temperature. Scanning tunneling microscopy and spectroscopy, as well as Auger spectroscopy, have been employed to identify the results and products of the adsorption of nitrous oxide on the surface of individual Pt nanoparticles synthesized on highly oriented pyrolytic graphite. It has been shown that, at short exposures, oxygen atoms resulting from dissociative adsorption oxidize the surface of nanoparticles only near the platinum–graphite interface. As the exposure increases, the entire surface of the nanoparticles is covered with oxide. Thus, it has been shown that the adsorption properties of the surface of the platinum nanoparticles on graphite are not the same, and this fact provides the possibility to carry out different chemical reactions on different surface regions, thereby increasing the efficiency of the catalytic system as a whole.

The formation of cobalt particles in the presence of water-soluble polymers of various nature was studied. The use of polyethyleneimine made it possible to prepare a dispersion of cobalt particles with a narrow size distribution. The use of polystyrenesulfonic acid and poly-N-vinylpyrrolidone led to the formation of a dispersion of cobalt particles 1.8–35.0 nm in size. In the presence of polyacrylic acid, particles 3.5–19.5 nm in size are formed, which consist of cobalt oxide and metallic cobalt.

The interaction of CO and H-2 with single clusters of gold and copper-based nanoparticles in the presence of an electric field has been studied. It is shown that depending on the direction of the electric field vector, the adsorption of molecules from the gas phase is stimulated or inhibited. Mechanisms of influence of the field on chemical processes are proposed.

Data have been presented on the interaction of H-2 and CO with oxidized platinum nanoparticles applied onto the surface of highly oriented pyrolytic graphite. At low exposures (of nearly 100 Langmuir), this process starts from the tops of the nanoparticles. Thus, the chemical properties of the periphery and tops of platinum nanoparticles with respect to H-2 and CO are significantly different. It has been revealed that the results of the interaction of the gases with the oxidized nanoparticles depend on the diameters of the latter.

The effect of poly-N-vinylpyrrolidone on the size characteristics, morphology, composition of particles obtained by the reduction of cobalt ions in aqueous solutions, and the distribution of particles over the surface of glass microspheres has been studied. The reduction of cobalt ions in the absence of poly-N-vinylpyrrolidone leads to the formation of particles with a size of 200 nm on the surface of glass microspheres. The use of poly-N-vinylpyrrolidone made it possible to obtain particles ranging in size from 30 to 300 nm, with a more localized distribution of particles on the surface of glass microspheres. The resulting particles are a mixture of metallic cobalt and cobalt oxides.

The quantum-chemical modeling of copper nanoparticles on graphite substrates with various defects shows a stronger decrease in the density of the states of copper atoms during hydrogen adsorption near the interface compared to similar adsorption far from it. It is also found that, in general, the effect of the substrate on the atomic and electronic structures of the copper nanoscale system is less pronounced than that of the gold nanoscale system.

Using the density functional theory (DFT) simulation of the adsorption of atomic oxygen and hydrogen on the surface of nickel and platinum nanoparticles on graphite substrates with various defects, we calculate the binding energies of adatoms and changes in the density of states of metal atoms upon interaction with adatoms. It is found that the density of states decreases more when oxygen is adsorbed at the top of a metal cluster than when oxygen is adsorbed at the interface between the metal cluster and the graphite substrate. For hydrogen adsorption, no such dependences are found. It is shown that the effect of monatomic defects of the substrate is insignificant in the case of adsorption of both types of adatoms.

Conditions were determined for the formation of a ternary complex of polyethylenimine with copper and cobalt ions, ensuring the predominant binding of the metal ions with the macromolecule of the polyethylenimine stabilizer. Metal particles were prepared under the conditions of different binding of metal ions with the stabilizer. The reduction of cobalt and copper ions in the presence of polyethylenimine yields Cu and Co metal nanoparticles irrespective of the mode of metal ion binding with the stabilizer. The metal particles obtained using the preliminarily prepared ternary complex of polyethylenimine with Cu2+ and Co2+ ions have approximately spherical shape and smaller characteristic size compared to the particles prepared without this complex. In the latter case, the particles are anisometric aggregates elongated in one direction.

The influence of the nature of the water-soluble polymer on the dimensional characteristics, morphology and chemical composition of cobalt-containing particles obtained in polymer films has been investigated. In the presence of polystyrene sulfonic acid and polyacrylic acid, polydisperse particles with a size of 20-50 nm are formed, forming aggregates of various structures. In the poly-N-vinylpyrrolidone film, the resulting particles are uniformly distributed over the film surface, do not form aggregates and have an average size of 30-40 nm. The chemical composition of the resulting particles was determined by X-ray microanalysis.