Nanoparticles, due to their unique size-dependent properties, distinct from those of bulk materials, have become a rapidly developing and intensively studied area of chemistry. These properties include the ability to catalyse chemical reactions, reduced melting temperatures, and distinctive optical characteristics. In this paper, we investigate these features in bimetallic Ag@Ni core-shell nanoparticles of varying composition. The nanoparticles were synthesised via a solvothermal method using silver nitrate and nickel(ii) acetylacetonate in a mixture of oleylamine and octadec-1-ene as solvents. Characterisation was carried out using a series of spectroscopic and microscopic methods. Catalytic activity and surface processes leading to the production and release of carbon dioxide were examined using Knudsen effusion mass spectrometry (KEMS). The highest catalytic activity was noted for Ag-Ni nanoparticles containing approximately 30-50 at% silver. The catalytic process is accompanied by the formation of organometallic compounds, which were detected by X-ray photoelectron spectroscopy (XPS) and laser ablation-inductively coupled plasma mass spectrometry (LA-ICP-MS). Thermal stability during heating was evaluated by differential scanning calorimetry (DSC), and a melting point depression of approximately 10 °C was observed for all studied samples. The paper is a part of a broader study of Ni-based bimetallic nanoparticles, their thermal stability and catalytic activity.

Boroaluminates are promising materials for various catalytic applications, particularly due to their tunable acidity and textural properties, although they have not yet reached their full potential. Developing synthetic routes that yield mesoporous structures with high surface areas is crucial for maximizing their performance. Traditional preparation methods (including hydrolytic sol-gel) often struggle to produce highly mesoporous, high-surface-area boroaluminates without the use of templating agents and can lead to heterogeneous elemental distribution. Furthermore, direct comparisons of different non-hydrolytic sol-gel (NHSG) approaches for these materials are limited. In this work, we present an NHSG preparation method for mesoporous boroaluminates, utilizing the alkyl-halide condensation reaction between Al(OiPr)3 and BCl3, with a 1:1 boron/aluminum precursor ratio. This approach resulted in amorphous xerogels featuring a homogeneous distribution of boron and aluminum atoms within the structure. Our method successfully produced mixed boria-alumina xerogels with high surface areas, reaching up to 600 m2 g−1 without the need for any templating agent. We characterized these materials using 11B and 27Al MAS NMR spectroscopy, SEM and STEM-EDS microscopy, N2 porosimetry, thermogravimetry, ICP-OES and XPS elemental analysis and ammonia-TPD. Additionally, we provide a comparative analysis with boroaluminates prepared by other non-hydrolytic sol-gel reactions and demonstrate their practical utility in catalysis through ethanol dehydration (with >83

Nonoxidative ethanol dehydrogenation opens a pathway for the sustainable production of acetaldehyde and butadiene. One crucial aspect of producing butadiene by the Lebedev process is the high-temperature stability of ethanol to acetaldehyde conversion. However, copper-based catalysts, despite exhibiting high activity and selectivity, suffer from sintering and coking and need to be improved for successful industrial applications. Herein, we show Cu-based (∼2.5 wt %) catalysts doped with Ni and Zn (0.028-0.36 wt %) to improve the catalytic performance of nanoparticles. The catalysts were prepared by hydrolytic sol-gel and dry impregnation methods. STEM analysis determined the nanoparticle sizes in the 1.9-2.8 nm range. Ni-doped catalysts outperformed the parent Cu catalysts in ethanol dehydrogenation activity at lower temperatures (185-220 °C) but suffered from faster deactivation. The Zn-doped catalysts exhibited improved high-temperature stability. For these materials, acetaldehyde selectivity fluctuated around ∼90% and acetaldehyde productivity reached 3.63 g g-1 h-1 at 290 °C and a WHSV of 4.73 h-1. The improved stability of the Zn-doped samples was correlated with lower coke formation (XPS, TG analysis, and Raman spectroscopy).

Carbon dioxide utilization presents an important and topical research topic. However, the performance of catalysts needed for CO2 transformations does not achieve the necessary levels for their widespread application. To this end, we decided to study non-aqueous condensations providing amine-functionalized silica catalysts, possibly active in CO2-epoxide cycloaddition reaction. While non-hydrolytic sol-gel method is well-known for its efficiency in providing highly porous Lewis and Brønsted acid metallosilicates, here we show for the first time its application for the preparation of silica-based catalysts containing basic groups. First, the reaction conditions were screened to reproducibly obtain porous materials with preserved amine moieties. These were identified as follows: silicon tetraacetate and bridging tertiary amine silanes as precursors, toluene as a solvent, and temperature between 160 and 180 °C. In such a way, materials with up to 776 m2 g−1 and 1.58 cm3 g−1 were obtained in one-step process, without any template, after conventional drying step. Next, the amine-functionalized materials were tested in CO2-epoxide coupling providing cyclic organic carbonates with high selectivity (>99 %) and moderate activity (up to 86 % epichlorohydrin conversion after 1 h at 120 °C and 10 bar CO2). The characterization of spent catalysts revealed a presence of cyclic organic carbonates at the catalyst surface as well as conversion of tertiary amine groups to quaternary ammonium moieties.

Synthesis of 1,3-butadiene (BD) from ethanol has experienced a true renaissance in recent years due to ecological and economic reasons. The open porosity and number of Lewis acid sites in metal silicates (M = Zr, Ta) have been reported in numerous studies as key factors enabling reaching high BD productivity. However, some microporous zeolites recently displayed very high BD productivity. To gain a deeper insight, we have applied non-hydrolytic sol-gel (NHSG) – a method well-known to produce highly porous and homogeneous metal silicates – in the preparation of zirconosilicates with varying micropore volume. The porosity (N2 adsorption-desorption experiments), structure (IR, XPS, NMR, and DRUV-Vis spectroscopy, XRD, MAS NMR), and acidity (IR spectroscopy combined with pyridine adsorption) of these materials have been described in detail and compared to a benchmark sample prepared by dry impregnation. Above mentioned characterization methods proved that NHSG preparation provided highly homogeneous Zr dispersion in silica leading to almost doubled Lewis acid site numbers and higher activity in ethanol-to-butadiene (ETB) transformation, Meerwein-Ponndorf-Verley (MPV) redox reaction, and aldol condensation, in comparison to the catalyst prepared by dry impregnation. The fraction of micropore volume in micro-mesoporous samples (ranging from 27 % to 69 %) did not play a significant role: The activity in all three catalytic reactions followed the acid site numbers. The selectivity and long-term stability in ETB process were similar for catalysts prepared by NHSG and dry impregnation.

Non-oxidative ethanol dehydrogenation is a renewable source of acetaldehyde and hydrogen. The reaction is often catalyzed by supported copper catalysts with high selectivity. The activity and long-term stability depend on many factors, including particle size, choice of support, doping, etc. Herein we present four different synthetic pathways to prepare Cu/SiO2 catalysts (~2.5 wt% Cu) with varying copper distribution: hydrolytic sol-gel (mostly atomic dispersion), dry impregnation (Ā = 3.9 nm; σ = 1.4 nm and particles up to 22 nm), strong electrostatic adsorption (Ā = 2.6 nm; σ = 1.0 nm) and solvothermal hot injection followed by Cu particles deposition (Ā = 14.7 nm; σ = 3.1 nm). All materials were characterized by ICP-OES, XPS, N2 physisorption, STEM-EDS, XRD, and H2-TPR, and tested in ethanol dehydrogenation from 185 to 325 °C. The sample prepared by hydrolytic sol-gel exhibited mostly atomic Cu dispersion and, accordingly, the highest catalytic activity. Its acetaldehyde productivity (2.79 g g−1 h−1 at 255 °C) outperforms most of the Cu-based catalysts reported in the literature, but it lacks stability and tends to deactivate over time. On the other hand, the sample prepared by simple and cost-effective dry impregnation, despite having Cu particles of various sizes, was still highly active (2.42 g g−1 h−1 acetaldehyde at 255 °C) and it was the most stable sample out of the studied materials. The characterization of the spent catalyst confirmed its exceptional properties: it showed the lowest extent of both coking and particle sintering.

Non-oxidative ethanol dehydrogenation opens a road for sustainable production of acetaldehyde and butadiene. One crucial part of producing butadiene by the Lebedev process is high-temperature stability of ethanol-to-acetaldehyde conversion. However, copper-based catalysts, despite exhibiting high activity and selectivity, suffer from sintering and coking and need to be improved for successful industrial application. Herein, we show Cu-based (~2.5 wt%) catalysts doped by Ni and Zn (0.02−0.3 wt%) to improve the catalytic performance of nanoparticles. Catalysts were prepared by hydrolytic sol-gel and dry impregnation. STEM analysis determined nanoparticle sizes in the 1.9−2.8 nm range. Ni-doped catalysts outperformed parent Cu catalysts in ethanol dehydrogenation activity at lower temperatures (185-220 °C) but suffered from faster deactivation. Zn-doped catalysts exhibited an improved high-temperature stability. For these materials, acetaldehyde selectivity fluctuated around ~90 % and acetaldehyde productivity reached 3.63 g · g−1 · h−1 at 290 °C. The improved stability of Zn-doped samples correlated with a lower coke formation (TG analysis).

Amidst growing concerns over the environmental impact of petroleum-based industries and their contribution to global ecological challenges, there is a pressing need for sustainable alternatives in chemical synthesis. This study addresses this imperative by exploring an innovative catalytic approach for the eco-friendly production of acetaldehyde from ethanol, a crucial chemical feedstock. Catalysts utilized so far perform poorly due to their low stability. Supported copper nanoparticles at higher temperatures suffer from the rapid deactivation caused by nanoparticles sintering and reduction of active sites by coking. To address this issue, the advanced copper nanoparticle-decorated silica nanofibres (107 nm in diameter) with outstanding surface area (700 m2 g−1) were synthesized and tested, showing enhanced stability in comparison to benchmark (Aerosil 300 SiO2/Cu). Two approaches were compared for the preparation of copper catalyst, i.e., dry impregnation and one-pot synthesis. Remarkably, the dry-impregnated DI-9.4 sample at 325 °C after 100 h maintained over 66 % of ethanol conversion with 99 % selectivity to acetaldehyde (acetaldehyde productivity: 3.09 g g h–1). This stability values surpass the benchmark catalyst, which dropped to 40 % of ethanol conversion. Our findings highlight the potential of the superior morphological advantage of electrospun SiO2 nanofibers as an efficient catalyst.

Metallic tungsten microfibers were prepared in a multigram yield by electrospinning from the aqueous phos-photungstic acid/polyvinyl alcohol (PVA) solution in three steps. Green composite microfibers of H3PW12O40 /PVA were easily electrospun from precursor solutions on a Nanospider instrument with a cylindrical rotating electrode. Subsequent oxidation of the organic PVA matrix and decomposition of phosphotungstic acid in the air at 600 degrees C provided ceramic WO3/P2O5 fibers. Finally, prepared oxide fibers were reduced in a forming gas at-mosphere at temperatures up to 1000 degrees C. During the reduction, all phosphorus was removed, and pure metallic tungsten microfibers were produced.

Non-oxidative ethanol dehydrogenation is a renewable source of acetaldehyde and hydrogen. The reaction is often catalyzed by supported copper catalysts with high selectivity. The activity and long-term stability depend on many factors, including particle size, choice of support, doping, etc. Herein we present four different synthetic pathways to prepare Cu/SiO2 catalysts (~2.5 wt% Cu) with varying copper distribution: hydrolytic sol-gel (mostly atomic dispersion), dry impregnation (Ā = 3.9 nm; σ = 1.4 nm and particles up to 22 nm), strong electrostatic adsorption (Ā = 2.6 nm; σ = 1.0 nm) and solvothermal hot injection followed by Cu particles deposition (Ā = 14.7 nm; σ = 3.1 nm). All materials were characterized by ICP-OES, XPS, N2 physisorption, STEM-EDS, XRD, and H2-TPR, and tested in ethanol dehydrogenation from 185 to 325 °C. The sample prepared by hydrolytic sol-gel exhibited mostly atomic Cu dispersion and, accordingly, the highest catalytic activity. Its acetaldehyde productivity (2.79 g g−1 h−1 at 255 °C) outperforms most of the Cu-based catalysts reported in the literature, but it lacks stability and tends to deactivate over time. On the other hand, the sample prepared by simple and cost-effective dry impregnation, despite having Cu particles of various sizes, was still highly active (2.42 g g−1 h−1 acetaldehyde at 255 °C) and it was the most stable sample out of the studied materials. The characterization of the spent catalyst confirmed its exceptional properties: it showed the lowest extent of both coking and particle sintering.

The open porosity and number of Lewis acid sites in metal silicates (M = Zr, Ta) have been reported as key factors enabling reaching high butadiene (BD) productivity from ethanol. However, some microporous zeolites recently displayed very high BD yields. To gain a deeper insight, we have applied non-hydrolytic sol-gel (NHSG) in the preparation of micro-mesoporous zirconosilicates. The porosity, structure, and acidity of these materials have been described and compared to a benchmark sample prepared by dry impregnation. The detailed characterization proved that NHSG preparation provided highly homogeneous Zr dispersion in silica leading to almost doubled Lewis acid site numbers and higher activity in ethanol-acetaldehyde conversion to BD, MeerweinPonndorf-Verley (MPV) reaction, and aldol condensation, in comparison to the catalyst prepared by dry impregnation. The selectivity and stability were similar for catalysts prepared by NHSG and dry impregnation.

Nowadays, the production of acetaldehyde heavily relies on the petroleum industry. Developing new catalysts for the ethanol dehydrogenation process, which could sustainably substitute current acetaldehyde production methods, is highly desired. Among ethanol dehydrogenation catalysts, copper-based materials have been intensively studied. Unfortunately, the Cu-based catalysts suffer from sintering and coking, which lead to rapid deactivation with time-on-stream (TOS). Phosphorus doping has been demonstrated to diminish coking in methanol dehydrogenation, fluid catalytic cracking, and ethanol-to-olefin reactions. This work reports a pioneering application of the well-characterized copper phosphinate complexes as molecular precursors for copper-based ethanol dehydrogenation catalysts enriched with phosphate groups (Cu-phosphate/SiO2). Three new catalysts (CuP-1, CuP-2, CuP-3), prepared by the deposition of complexes {Cu(SAAP)}n (1), [Cu6(BSAAP)6] (2), and [Cu3(NAAP)3] (3) on the surface of commercial SiO2, calcination at 500 °C, and reduction in the stream of the forming gas 5% H2/N2 at 400 °C exhibited unusual properties. First, the catalysts showed a rapid increase in catalytic activity. After reaching a maximum conversion, the catalyst started to deactivate. The unusual behavior could be explained by the presence of the phosphate phase, which prevented the Cu2+ reduction. The phosphorus content gradually decreased during time-on-stream, copper was reduced, and the activity increased. The deactivation of the catalyst could be related to the copper diffusion processes. The most active CuP-1 catalyst reaches a maximum of 74 % ethanol conversion and over 98 % acetaldehyde selectivity at 325 °C and WHSV = 2.37 h−1.

Nickel nanoparticle–decorated reduced graphene oxide nanocomposites (NiG) were prepared by a one-step microwave-assisted solvothermal method. The as-prepared NiG nanocomposite systems were further heated up to 800 °C under an inert atmosphere (named NiG-800) to modify their structural and electromagnetic properties. Thereafter, these developed NiG-800 nanocomposite systems of rGO and nickel nanoparticles (25 wt.%) were applied as nanofillers (50 wt.% and 70 wt.%) in a SEBS (Polystyrene- block -poly(ethylene- ran -butylene)- block -polystyrene) polymer matrix to create NiG-800(50)-SEBS and NiG-800(70)-SEBS nanocomposites. The addition of NiG-800 to SEBS led to an increase of Young’s modulus from 16 (SEBS) to 35 MPa (NiG-800(70)-SEBS) while the maximum elongation is still around 300%. The developed NiG-800(70)-SEBS nanocomposite exhibited high-performance electromagnetic wave absorption (minimum reflection loss RL min ≈ –48.2 dB at 9.29 GHz) at a low thickness of 2.3 mm in the frequency range of 8.2−12.4 GHz. The prepared NiG-800(70)-SEBS nanocomposite has the potential of an electromagnetic wave absorber. The NiG-800(70)-SEBS nanocomposite reported here has total shielding efficiency > 10 dB at a thickness of 1 mm in the whole frequency range (X-band) with reflection ≈ 50% and absorption ≈ 40% which has the potential for electromagnetic wave absorber applications.

In this work, we demonstrate that amorphous and porous molybdenum silicate microspheres are highly active catalysts for heterogeneous propylene metathesis. Homogeneous molybdenum silicate microspheres and aluminum-doped molybdenum silicate microspheres were synthesized via a nonaqueous condensation of a hybrid molybdenum biphenyldicarboxylate-based precursor solution with (3-aminopropyl)triethoxysilane. The as-prepared hybrid metallosilicate products were calcined at 500 °C to obtain amorphous and porous molybdenum silicate and aluminum-doped molybdenum silicate microspheres with highly dispersed molybdate species inserted into the silicate matrix. These catalysts contain mainly highly dispersed MoOx species, which possess high catalytic activity in heterogeneous propylene metathesis to ethylene and butene. Compared to conventional silica-supported MoOx catalysts prepared via incipient wetness impregnation (MoIWI), the microspheres with low Mo content (1.5-3.6 wt %) exhibited nearly 2 orders of magnitude higher steady-state propylene metathesis rates at 200 °C, approaching site time yields of 0.11 s-1.

We disclose the preparation of high-surface-area mesoporous zirconium phosphonates by the non-hydrolytic solgel reactions (NHSG) of Zr(NEt2)4 with trimethylsilylated phosphonates RP(O)(OSiMe3)2 (R = Me, tBu, Ph, OSiMe3), and bis-phosphonates (Me3SiO)2(O)P-X-P(O)(OSiMe3)2 (X = CH2, C6H4, CH2(C6H4)CH2, and CH2(C6H4)2CH2) in dry toluene under ambient pressure. Zirconium phosphonate xerogels are prepared by condensation reaction with the elimination of silylamine Me3SiNEt2. This irreversible reaction provides the amorphous xerogels and drives the formation of the porous structure. The influence of organic moieties bonded to phosphorus atoms on porosity was examined in this study. The final surface area of dried xerogels reached 720 m2 g-1 without any extra templating agent. Xerogels were characterized by 13C, 29Si, and 31P solid-state NMR to define atomic homogeneity and evidence the presence of organic phosphonate substituents and residual amido and trimethylsilyl groups. The amount of residual reactive groups was determined by gravimetric measurements and the thermal analysis (TG-DSC) method. These groups may be applied in post-synthetic surface modification, such as controlling the hydrophobic/hydrophilic properties.The catalytic properties of NHSG-prepared xerogels were tested on a model reaction of aminolysis of styrene oxide in a batch mode employing relatively bulky molecules. Products were identified and quantified by the 1H NMR spectroscopy. Catalyst performance parameters, such as selectivity, conversion, turnover frequency, and others, were exceeded compared to benchmark microporous layered zirconium phosphonate catalysts.

Design and properties of a plasmonic modulator in situ tunable by electric field are presented. Our design comprises the creation of periodic surface pattern on the surface of an elastic polymer supported by a piezo–substrate by excimer laser irradiation and subsequent selective coverage by silver by tilted angle vacuum evaporation. The structure creation was confirmed by AFM and FIB-SEM techniques. An external electric field is used for fine control of the polymer pattern amplitude, which tends to decrease with increasing voltage. As a result, surface plasmon–polariton excitation is quenched, leading to the less pronounced structure of plasmon response. This quenching was checked using UV–Vis spectroscopy and SERS measurements, and confirmed by numerical simulation. All methods prove the proposed functionality of the structures enabling the creation smart plasmonic materials for a very broad range of advanced optical applications.

In this work, a novel synthesis of homogeneous molybdenum silicate spheres under non-aqueous conditions is presented. A preparation method is based on the condensation of molybdenum metal-organic framework-based precursor solution prepared via a microwave-assisted approach from bis(acetylaceto nato)dioxomolybdenum and biphenyl-4,40-dicarboxylic acid with 3-aminopropyltriethoxysilane under non-aqueous conditions. The as-prepared product was calcined at 500 degrees C to obtain amorphous and porous molybdenum silicate microspheres with homogeneously distributed molybdenum species within silicate matrix. The microspheres exhibit an average size of about 480 nm. This material was further studied as a heterogeneous catalyst for the epoxidation of olefins via the model catalytic epoxidation of cyclohexene with cumylhydroperoxide. High catalytic activity at the moderate temperature (65 degrees C) with the conversion of 86% after 2 h and the high selectivity to cyclohexene oxide has been achieved. In addition, molybdenum silicate microspheres exhibit catalytic activity and high selectivity in the oxidation of aniline to nitrosobenzene. (c) 2021 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.

We disclose the preparation of high-surface-area mesoporous aluminophosphates and aluminophosphonates by the non-hydrolytic sol-gel reactions (NHSG) of Al(NMe2)(3) with trimethylsilylated phosphate OP(OSiMe3)(3), phosphonates RP(O)(OSiMe3)(2) (R = Me, tBu, Ph), and bis-phosphonates (Me3SiO)(2)(O)P-X-P(O)(OSiMe3)(2) (X = C6H4, (C6H4)(2)) in dry toluene. The reactions proceed by silylamine elimination of Me3SiNMe2 to provide organicinorganic hybrid xerogels with properties influenced by organic substituents and the Al:P ratio of the precursors. Dried xerogels exhibit large surface areas (up to 1000 m(2) g(-1)) and matrices based on condensed Al-O-P networks. They stay stable under relatively harsh thermal conditions. Al-27, C-13, and Si-29 solid-state NMR spectroscopy was employed to characterize the aluminum coordination and the residual amido and trimethylsilyl groups. The catalytic performance of NHSG prepared material was examined in gas-phase dehydration of ethanol to ethylene exhibiting conversion and selectivity comparable to weak solid acid benchmark catalysts. The number of unreacted surface groups was determined by gravimetric measurements and by thermal analysis (TGDSC). These residual groups have the potential to be used in post-synthetic grafting of catalytically active metal centers.

Development of materials with highly nonlinear optical activity represents an intensively studied discipline due to potentially unique applications of such materials in photonics and information technologies. In this work the creation of ordered nanostructured arrays of c-shaped metals (Ag, Au, Al, and Pd) and characterization of their nonlinear optical properties are described. Large scale ordered arrays were created by the excimer laser pattering of a polymer surface and subsequent coating with Ag, Au, Al, and Pd. The successful creation of required structures was confirmed by the conductive AFM and FIB-SEM techniques. Linear optical response of the structures was examined using the UV–Vis technique and strong excitation of surface plasmon polariton resulting in appearance of strong absorption band was confirmed. The Z-scan technique with femtosecond laser pulses was used to determine the nonlinear optical response of the prepared metal arrays. It was found that the strong two-photon absorption appears under the illumination at the wavelength corresponding to the surface plasmon excitation. Extensive comparison with available literature data shows that the present structures exhibit markedly higher two-photon absorption activity.

Abstract Graphene preparation by the method of chemical vapour deposition on SiC substrates is described. Despite very low growth temperature (1080 °C) and with use of methane atmosphere, carbon layers in the form of multi-layer graphene were prepared. Graphene quality was verified by means of available analytical methods: Raman spectroscopy, X-ray photoelectron spectroscopy, Van der Paw method.