The paper reports a facile way for noncovalent functionalization of 1T-MoS2 with L-lysine (Lys) monolayers. The structure of the resultant hybrid compound was revealed by the powder X-ray diffraction (PXRD), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy, absorption spectroscopy and density functional theory (DFT) calculations study. A significant strength of the in-layer organic and organic-inorganic hydrogen bonding amounting to 24.6 and 29.9 kcal per mole of Lys, respectively, was found to hold the hydrated Lys molecules arranged in 2D chains and keep these chains tightly bound to the MoS2 sheets. The MoS2 hybridization with Lys significantly rises the upper temperature stability limit of 1T-MoS2 polymorph, which possesses the remarkable photothermal properties in near infra-red (NIR) region. The hybrid structure demonstrates excellent photothermal light-to-heat conversion efficiency reaching 49.5% upon 808 nm laser irradiation and higher thermal durability than unmodified 1T-MoS2.

1T-MoS2 shows great promise for hydrogen production due to phenomenal performance in catalyzing hydrogen evolution reaction (HER) from water. However, this phase converts to low-active 2H–MoS2 on superambient heating. A series of MoS2 layered compounds (LCs) with guest organic cations was prepared to reveal the effect of cationic organics on the structure stabilization of 1T-MoS2 and thereby on the catalytic performance of this phase in HER. The results showed that LCs provide significantly higher 1T/2H ratio after heating than non-stabilized 1T phase and some of them exhibit excellent thermal durability in the capacity of HER catalysts. The effect is most pronounced for the organics remaining tightly bound to sulfide sheets in a sulfuric acid electrolyte. Cetyltrimethylammonium and bis(dimethylamino)naphthalene perfectly matched this criterion and provided a long-term maintaining of catalyst activity. The data obtained in this study are hoped to offer new approach for rational design of the efficient non-precious 1T-MoS2-based electrocatalysts for hydrogen production.

Glassy carbon supported Ni/GC and amorphous Ni-P/GC electrodes were prepared by potentiostatic electrodeposition. The catalysts have been characterized by X-ray powder diffraction, transmission and scanning electron microscopy, and cyclic voltammetry. Particular attention has been paid to the influence of electrochemical oxidation on the electrochemical behavior of Ni-P/GC and Ni/GC electrodes in alkaline media as well as the activity of these electrodes in the hydrogen oxidation reaction (HOR). It was found that the oxidation treatment changes the properties of Ni/GC electrode due to the formation of active Ni/NiOx surface sites, while insignificantly affecting the performance of Ni-P/GC sample. The unordinary behavior of electrodeposited Ni-P/GC samples is tentatively attributed to their amorphous structure and the formation of nickel phosphate under high anodic potentials, which prevents the formation of irreversible Ni oxides.

Metallic Co nanoparticles, widely used and studied as supported heterogeneous catalysts for Fischer-Tropsch synthesis (FTS), display catalytic properties that can vary significantly depending on their size and crystal structure. In this work, we used 59Co Internal Field NMR (59Co IF NMR) complemented by high-resolution transmission electron microscopy (HRTEM) to demonstrate the influence of strong metal-support interaction on two noticeably different metastable alumina phases - γ-Al2O3 and χ-Al2O3. According to 59Co IF NMR and HRTEM, the metallic particles supported on χ-Al2O3 were larger and displayed a significantly higher content of hcp Co phase, which are known to be more active and selective to C5+ in FTS. The 1H NMR chemical shifts of hydroxyl groups anchored to the (110) and (111) spinel crystal planes were calculated by DFT. It revealed that the hydroxyl coverage of γ-Al2O3 facilitates the dispersion of Co precursor over the surface of the support, ultimately leading to the formation of smaller metal Co nanoparticles on γ-Al2O3, than on χ-Al2O3 .

Zn aluminosilicates of a ZSM-5 zeolite structural type are synthesized from alkaline alumino-silica gels via hydrothermal crystallization. Structural and morphological data on the samples show that incorporating zinc into the zeolite structure leads to the formation of the particles of different morphology and elemental composition. Data from EDX analysis show that the distribution of elements throughout the zeolite catalyst is almost uniform, due to the morphology of the crystals that form. It is found that Zn aluminosilicates have high catalytic activity in the conversion of propane into aromatic hydrocarbons. A 0.81% Zn-AC sample exhibits the greatest selectivity toward aromatic compounds, due to the specific distribution and state of Zn in the zeolite and its acidic properties.

The article provides information about the history of formation, development, main recent activities and achieved results of the Analytical and Technological Research Center of the Faculty of Physics of Novosibirsk State University (ATRC NSU) during its 15 years of operation. The main areas of physical research are: modern materials science, nanomaterials, nanotechnologies and technological processes, experimental diagnostics of structures and substances, development of methods for nanostructures fabrication, computer simulation of low-dimensional structures, improvement of the characteristics of solid-state semiconductor electronics, search for materials for storage and transfer of digital information, study of technological properties of low-dimensional semiconductors, catalysts, metamaterials and organic optoelectronics, study of materials and systems for terahertz electronics. Due to the organization of the Shared Research Facilities “High Technologies and Analytics of Nanosystems” (CCU “VTAN”) within the structure, ATRC successfully cooperates with scientific and educational organizations and with industrial companies of the real sector of the economy in the Siberian region, Russia and neighboring countries. The main part of scientific research is carried out by the staff of the youth Laboratory of Functional Diagnostics of Nanoscale Systems for Nanoelectronics (LabFDNS) that contributes to the involvement of students and young employees of NSU into the implementation of relevant in-demand research work, and thus provides them with a high level of training in their chosen specialty.

Heterolayer MoS 2 compounds with molecules of protonated guanidine (GUA) and its aliphatic derivative 1,5,7- triazobicyclo[4.4.0]dec-5-ene (TABD) are prepared using single-layer dispersion of molybdenum disulfide. The structure of these compounds, including the geometry of sulfide layers and the localization of organic cations, is determined by powder X-ray diffraction, transmission electron microscopy, thermogravimetric analysis, differential scanning calorimetry, and density functional theory (DFT) calculations. The analysis of the topology and energy characteristics of non-covalent bonding interactions within the Quantum Theory of Atoms in Molecules shows that the contribution of NH…S bonds to the stabilization of the heterolayer structure is essential in the compound with GUA and is significantly smaller than the contribution of CH…S contacts in the compound with TABD. Relation between the number and energetics of bonding contacts between the components with the geometry and positions of organic molecules in the interlayer space of MoS 2 is discussed.

Zinc-isomorphously substituted HZSM-5 (Zn/HZSM-5(iso)) surpasses Zn/HZSM-5(i.e) sample obtained by ion exchange in its catalytic performance in the conversion of a mixture of DME + syngas (in different compositions) to liquid hydrocarbons. The uniform distribution of highly dispersed zinc species over zeolite crystals provides high selectivity of Zn/HZSM-5(iso) to liquid hydrocarbons (90 wt%). New ZnOH+ active sites of medium strength with mild hydrogenation properties explain the low yield of arenes (4.7 wt%) and the high yield of i-alkanes (72.5 wt%). The absence of methanol in the product stream indicates its dehydration to DME, which is known to have a higher reactivity or its participation in the methylation of alkenes to form methyl-substituted alkanes. A larger mesopores volume in Zn/HZSM-5(iso) promotes a lower degree of coke precursors polycondensation. Therefore, this allows the use of mild oxidative regeneration conditions. The Zn/HZSM-5(iso) catalyst retains its efficient and stable operation for 72 h, with high conversion of DME and high selectivity for liquid hydrocarbons. The resulting hydrocarbon mixture can be used as a base component for environmentally friendly fuels.

Emerging interest in the platinum group metal (PGM)-free electrocatalysts calls for a fundamental understanding of the key factors determining their activity, the latter being critical for the development of efficient catalysts. Ni-based materials show high promises as PGM-free anodes of anion exchange membrane fuel cells (AEMFCs). However, their hydrogen oxidation reaction (HOR) activity can differ by several orders of magnitude, and the factors responsible for this are still being debated. In this work, the effect of unintentional surface oxides in Ni/C and NiM/C (M = Cu and Mo) is revealed by benchmarking either the catalysts conventionally stored under ambient conditions or purposely reduced "oxide-free" materials. The analysis of electrocatalytic data complemented by detailed material characterization, Monte Carlo simulations, and density functional calculations, underlines the key importance of surface oxides in the HOR catalysis on Ni, NiCu, and NiMo electrodes. These findings underscore the need to measure the HOR activity of Ni-based catalysts in the absence of surface oxides in order to unambiguously interpret the influence of other factors (such as the electronic effect of the second element) on activity enhancement.

С применением монослоевого диспергирования дисульфида молибдена получены гетерослоистые соединения MoS2 с протонированными молекулами гуанидина (GUA) и его алифатического производного, 1,5,7-триазобицикло[4.4.0]дец-5-ена (TABD). Строение соединений, включая геометрию сульфидных слоев и локализацию органических катионов, установлено на основе данных порошковой рентгеновской дифракции (PXRD), просвечивающей электронной микроскопии (TEM), термогравиметрического анализа (TGA), дифференциальной сканирующей калориметрии (DSC) и квантово-химических расчетов методом функционала плотности. Анализ топологии и энергетических характеристик нековалентных связывающих взаимодействий в рамках теории “Атомы в молекулах” (AIM) показал, что вклад NH…S связей в стабилизацию гетерослоистой структуры, который является определяющим для соединения c GUA, существенно уступает вкладу CH…S контактов в случае соединения c TABD. Обсуждается взаимосвязь набора и энергетики связывающих контактов между компонентами с геометрией органических молекул и их положением в межслоевом пространстве MoS2.

In the present work, complex powder alloys containing spinel as a minor phase were produced by mechanical alloying in a high-energy planetary ball mill from a 33Al–45Cu–22Fe (at.%) powder blend. These alloys show characteristics suitable for the synthesis of promising catalysts. The alloying was conducted in two stages: at the first stage, a Cu+Fe powder mixture was ball-milled for 90 min; at the second stage, Al was added, and the milling process was continued for another 24 min. The main products of mechanical alloying formed at each stage were studied using X-ray diffraction phase analysis, Mössbauer spectroscopy, transmission electron microscopy, and energy-dispersive spectroscopy. At the end of the first stage, crystalline iron was not found. The main product of the first stage was a metastable Cu(Fe) solid solution with a face-centered cubic structure. At the second stage, the Cu(Fe) solid solution transformed to Cu(Al), several Fe-containing amorphous phases, and a spinel phase. The products of the two-stage process were different from those of the single-stage mechanical alloying of the ternary elemental powder mixture; the formation of undesirable intermediate phases was avoided, which ensured excellent composition uniformity. A sequence of solid-state reactions occurring during mechanical alloying was proposed. Mesopores and a spinel phase were the features of the two-stage milled material (both are desirable for the target catalyst).

CeO2 and binary La2O3-CeO2 oxides, with different La/Ce atomic ratios (1:4; 1:1; 4:1), were synthesized using sol-gel method in the presence of citric acid in ammonia solution, at pH similar to 9, and Ni (10 wt%) was added by wetness impregnation method. The physical-chemical properties, catalytic activity and long-run stability of the prepared catalysts were evaluated in DRM reaction. Characterizations of both fresh and spent catalysts were carried out using low-temperature N-2 adsorption, XRD, TGA, TPR, Raman and TEM analyses. The DRM gradient catalytic tests performed in the range of 400-800 degrees C revealed higher catalytic conversions for Ni/La2O3-CeO2 catalysts, especially for those with La/Ce ratio 1:4 and 1:1. The stable conversions of CH4 and CO2 (long run at 650 degrees C for 24 h) registered for such Ni/La2O3-CeO2 catalysts were attributed to the presence of small Ni crystallites. During long run tests, Ni/La2O3-CeO2 catalysts, with La/Ce atomic ratios 1:4 and 1:1, formed the same types of carbon, both as filaments and layered carbon with graphene structure, but their catalytic activity was retained. Ni/CeO2 showed the smallest content of carbon, however, exhibited lower CH4 and CO2 conversions in comparison with the Ni-La2O3-CeO2 systems, due to the presence of big Ni particles with sizes of up to 0.5 mu m.

Metastable modification of MoS2 (1T) is widely recognized as a hopeful non-precious electrocatalyst in hydrogen production. This paper describes an approach to impart a superambient temperature stability to 1T-MoS2 by incorporating it in 2D hybrid architecture with cationic monomolecular phenanthrolinium (PhenH(+)) hydrate layers. The atomic structure and bonding interactions of the assembled architecture revealed by PXRD, TEM, XPS, Raman and UV-Vis spectroscopy data coupled with DFT calculations and quantum theory of atoms in molecules (QTAIM) analysis suggest that the 1T-MoS2 sheets are involved in strong bonding with the PhenH-H2O layers. This results in a highly stable layered system, which is kept intact in 0.5 M sulfuric acid electrolyte and tolerates superambient temperature heating. As compared with pure 1T-MoS2, the compound with a phenanthroline interlayer provides greater activity and better current-voltage efficiency in electrocatalytic hydrogen evolution after heating treatment owing to stabilization of the 1T phase. The obtained results could be useful for the design of novel electrocatalytic devices exploiting 1T-MoS2 modification.

Two series of Ag-TiO2 photocatalysts were prepared with the use of photodeposition method with variation of the irradiation time and precursor concentration. The obtained photocatalysts were studied by XRD, Raman spectroscopy, HR TEM, UV-vis spectroscopy, and low-temperature N-2 adsorption/desorption method. It has been consequently found that the optical properties of the resulting catalysts differ significantly: the positions of surface plasmon resonance peaks red-shifted with the increase in precursor concentration. At the same time, optical absorption of the samples increases with both precursor concentration and irradiation time. Photo catalytic activity for the obtained catalysts was evaluated in decolorization of Rhodamine B with the use of Xe arc lamp (250 W) with and without lambda > 420 nm light filter. Radical trap experiments have shown that the amount of both superoxide anions and hydroxyl radicals increased in full spectrum of the lamp, with the latter being absent in the reaction mixture during visible light photocatalysis. Comparison of different Ag-TiO2 catalysts has also been made, with 1-Ag-90 min sample being the most active in full spectrum, and 3-Ag-90 min demonstrating the highest conversion in visible light attributed to the increased generation of superoxide species on the surface of Ag clusters. Controversially, 1-Ag-45 min sample showed the lowest activity in full spectrum being surpassed even by unmodified TiO2, but reached the highest rate constant value in visible light. This effect can be related to advanced electronic interaction between Ag plasmonic nanoparticles and titania support in the presence of sensitizer compound, and the formation of Ag/Ag2O composite system on the surface of titania. Influence of the state of silver on photocatalytic activity and mechanism details is discussed with special attention to irradiation wavelengths.

Методом импульсной лазерной абляции в жидкостях получен композитный катализатор Au/CeO2. Дисперсии золота и церия готовились в спирте и воде соответственно, затем смешивались, сушились при 60 °C и прокаливались при различных температурах: 450 °C, 600 °C, 800 °C. С применением физических методов (РФЭС, РФА, ПЭМВР, СКР) обнаружено возникновение контактного взаимодействия между частицами золота и диоксида церия вследствие прокаливания на воздухе или при воздействии реакционной среды. Методом РФЭС зафиксировано наряду с металлическими частицами появление ионной компоненты золота с Есв(Au 4f7/2) = 85.3 эВ. Из данных СКР (λ = 785 нм) следует, что наночастицы CeO2 сильно дефектны, золотые кластеры стабилизируются на вакансиях решетки диоксида церия. Каталитические испытания в реакции СО + О2 показали, что прокалка при 450—600 °C на воздухе или в реакционной среде активирует катализаторы и приводит к появлению высокой низкотемпературной активности. Рассчитанные значения частоты оборота активного центра составили 0.08 с–1 при 0 °C и 0.17 с–1 при 20 °C. Согласно данным РФА и РФЭС, прокаливание композита при 800 °C приводит к полному восстановлению золота и спеканию его в крупные частицы, а затем к потере низкотемпературной активности вследствие этого.

The physicochemical and catalytic properties of Mo/ZSM-5 catalysts for methane dehydroaromatization prepared using different (NH4- and H-) zeolite forms and nanosized Mo powder are studied. It is shown that the properties of the samples under study depend on the initial form of the zeolite used for their preparation. According to the data of electron microscopy and EDS analysis, the morphology and elemental composition of particles in the Mo/H-ZSM-5 and Mo/NH4-ZSM-5 samples are practically similar, and molybdenum is stabilized in the zeolite matrix in the form of the aggregates of atoms. The distribution profiles of silicon and molybdenum in the catalysts indicate that a more uniform distribution of molybdenum in the zeolite is observed for the Mo/NH4-ZSM-5 sample. Changes in molybdenum localization after methane dehydroaromatization were revealed. Molybdenum migration to the zeolite surface was observed, with the formation of MoCx particles up to 100 nm in size, coated with a carbon layer about 3 nm thick. It was established by means of the thermal desorption of ammonia that the concentration of strong acid sites in the catalyst prepared using the hydrogen form of the zeolite was lower than that for the catalyst prepared on the basis of the ammonium form of the zeolite. This difference in the acidic characteristics of the obtained Mo/ZSM-5 catalysts depends on the conditions of their preparation. The number of thermal treatments increased in the course of catalyst preparation using the hydrogen form of the zeolite, which resulted in the partial destruction of the zeolite crystal lattice with the formation of the Al-2(MoO4)(3) phase. Studies of the catalytic properties of the samples showed that the Mo/ZSM-5 catalyst prepared on the basis of ammonium zeolite exhibited the highest activity in the course of the nonoxidative conversion of methane to aromatic hydrocarbons.

The oxidized palladium nanoparticles comprising Pd4+ species were prepared by radio frequency (RF) discharge in an O-2 atmosphere and analyzed with X-ray photoelectron spectroscopy. PdOx particles were deposited on CeO2 or the reference support (Ta2O5) with variation of the RF sputtering time. Regardless of the used support, small PdOx particles (d < 1 nm) contained only Pd2+ species, while an increase of the particle size led to the appearance of the additional oxidized Pd state-Pd4+. The stabilization of Pd4+ on the surface of defect PdO particles was proposed. The Pd4+ species in the PdOx/CeO2 system was stable during heating in ultra-high vacuum conditions up to 250 degrees C. Pd4+ species demonstrated a high reaction probability toward CO oxidation at room temperature. However, a transition from the relatively inert support (Ta2O5) to the reducible oxide (CeO2) did not lead to a significant improvement of the Pd4+ reaction probability. Pd4+ species could not be recovered by the exposure of the reduced systems to molecular oxygen at room temperature. The obtained results bring new insights into consideration of Pd4+ species as active sites for oxidation processes at low temperatures.