Protocol for robust and efficient preparation of the self-blotting nanowire TEM grids

Functional sample comprises a protocol for preparation of the TEM grids coated with the Cu(OH)2 nanowires. Such TEM grids are specifically suitable for preparation of the macromolecular samples for cryo-electron microscopy using spray of piezo-dispenzing devices.Funkční vzorek poskytuje protokol pro přípravu TEM mřížek potažených vrstvou Cu(OH)2 nanovláken. Takové TEM mřížky jsou specificky vhodné pro přípravu komplexů makromolekul pro účely kryo-elektronové mikroskopie pomocí sprejovacího zařízení.Functional sample comprises a protocol for preparation of the TEM grids coated with the Cu(OH)2 nanowires. Such TEM grids are specifically suitable for preparation of the macromolecular samples for cryo-electron microscopy using spray of piezo-dispenzing devices

Chemical Wet Synthesis and Characterization of Copper-Silver Nanoparticles

AgCu nanoparticles (NPs) of near-eutectic composition were prepared by various route of wet synthesis. Nanoparticles suspended in nonpolar solvents were prepared by solvothermal synthesis from metallo-organic precursors. AgCu colloids in aqueous solution were obtained by hydride reduction of Ag and Cu nitrates under action of different stabilization substances. The different surface stabilizing agents were used. Chemical characterisations of as-synthesized AgCu NPs were done using inductively-coupled plasma-optical emission spectrometry (ICP-OES). The optical properties of nanoparticles were monitored using UV-Vis spectrophotometer. The size of colloid nanoparticles was measured by both dynamic light scattering (DLS) and small angle X-ray scattering (SAXS) method in some extra cases. Zeta potential of AgCu colloids was measured by electrophoretic method. Size and shape of metal core of nanoparticles and morphology of aggregates were investigated by electron microscopy (SEM, TEM and HRTEM), the thermal properties of AgCu nanoparticles were evaluated by differential scanning calorimetry (DSC) and temperature controlled X-ray diffraction method (t-XRD). Mass loss under heating inside inert and air was monitored by thermo gravimetric analysis (TGA). The fraction of organic matter was deduced from ICP-OES analysis and compared to TGA mass loss. The adsorption maxima in UV-Vis region were occurred. Hydrodynamic size of AgCu NPs measured by DLS was compared with the metallic core size obtained by electron microscopy. The morphologies of aggregates were observed as well as the phase transformation (t-XRD) that undergoes at heating to liquid temperature (DSC). The obtained results were compared with respect to perspective use.Nanočástice AgCu (NPS)s téměř eutektickým složením byly připraveny různými způsoby mokré syntézy. Nanočástice suspendované v nepolárních rozpouštědlech byly připraveny solvothermal syntézou z prekurzorů organokovovů. AgCu koloidy ve vodném roztoku byly získány hydridovou redukcí dusičnanů Ag a Cu za přítomnosti různých stabilizačních látek. Chemická složení bylo stanoveno pomocí indukčně vázané emisní spektrometrie (ICP-OES). Optické vlastnosti nanočástic byly sledovány pomocí UV-VIS spektrofotometru. Velikost koloidních nanočástic byla měřena jak dynamickým rozptylem světla (DLS) tak i metodou sledování XDR malých úhlů (SAXS). Zeta potenciál AgCu NPs byl měřen elektroforetickou metodou.Velikost a tvar kovového jádra nanočástic a morfologie agregátů byly zkoumány elektronovým mikroskopem (SEM, TEM a HRTEM), tepelné vlastnosti AgCu nanočástic byly hodnoceny pomocí diferenční skenovací kalorimetrie (DSC), a rentgenové difrakční metody s řízenou změnou teploty (t -XRD). Úbytek hmotnosti při zahřívání v inertu a na vzduchu byl sledován pomocí termogravimetrické analýzy (TGA). Frakce organické hmoty byla odvozena z ICP-OES analýzy a srovnání s TGA. Hydrodynamická velikost AgCu NP měřená DLS byla porovnána s velikostí kovového jádra

Ag-Cu Colloid Synthesis: Bimetallic Nanoparticle Characterisation and Thermal Treatment

The Ag-Cu bimetallic colloidal nanoparticles (NPs) were prepared by solvothermal synthesis from metalloorganic precursors in a mixture of organic solvents. The nanoparticles were characterized by dynamic light scattering (DLS) and small angle X-ray scattering (SAXS). The properties of metallic core and organic shell of the nanoparticles were studied by direct inlet probe mass spectrometry (DIP/MS), Knudsen effusion mass spectrometry (KEMS), double-pulse laser-induced breakdown spectroscopy (DPLIBS), and differential scanning calorimetry (DSC). The transmission electron microscopy (TEM) and scanning electron microscopy (SEM) were used for particle characterization before and after thermal analysis. The experiment yielded results that were for AgCu nanoparticles for the first time. The detected liquidus temperature has been compared with the prediction obtained from calculation of the phase diagram of Ag-Cu nanoalloy. The experimental results show that of near-eutectic composition AgCu nanoparticles possess the fcc crystal lattice. Surprisingly, spinodal decomposition was not observed inside the AgCu nanoparticles at temperatures up to 230C. The depression of the eutectic AgCu melting point was calculated but not observed. The eutectic AgCu microparticles are formed before melting.Ag-Cu bimetalické koloidní nanočástice (NPs) byly připraveny solvotermální syntézou z metalických prekurzorů ve směsi organických rozpouštědel. Nanočástice byly charakterizovány metodami: DLS a SAXS. Vlastnosti kovového jádra a stabilizační obálky z organických látek byly studovány metodou přímého vstupu do hmotnostního spektrometru (DIP/MS), Knutsenovou hmotnostní spektrometrií (KEMS), double -pulse laserovou spektroskopií (DPLIBS) a diferenční skenovací kalorimetrií (DSC). Transmisní elektronová mikroskopie (TEM) a řádkovací elektronová mikroskopie (SEM) byly použity pro charakterizaci částic před a po termické analýze. Teplota likvidu zjištěna experimentálně byla srovnávána s predikcí fázového diagramu Ag-Cu nanoslitiny. Experimentální výsledky ukázaly téměř eutektické složení a fcc krystalovou mřížku AgCu NPs. Překvapivě, spinodální rozklad nanočástic nebyl pozorován při teplotách do 230C

Propylene metathesis over molybdenum silicate microspheres with dispersed active sites

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-1CF CryoE; European Regional Development Fund-Project “UP CIISB, (CZ.02.1.01/0.0/0.0/18_046/0015974, LM2018110); Francqui Foundation; Grant Agency of Masaryk University, (MUNI/A/1298/2022, MUNI/J/0007/2021); U.S. Department of Energy, USDOE; Basic Energy Sciences, BES, (DE-SC0016214); Massachusetts Institute of Technology, MIT; Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT, (LM2023042, RP/CPS/2022/007); Grantová Agentura České Republiky, GA ČR, (GJ20-03636Y); Central European Institute of Technology, CEITECMinistry of Education, Youth, and Sports of the Czech Republic within the INTER-EXCELLENCE II program; Ministry of Education, Youth, and Sports of the Czech Republic [RP/CPS/2022/007]; U.S. Department of Energy, Office of Basic Energy Sciences [DE-SC0016214]; European Regional Development Fund-Project "UP CIISB" [CZ.02.1.01/0.0/0.0/18_046/0015974, LM2018110]; MEYS CR [GJ20-03636Y, LM2023042]; Czech Science Foundation; Grant Agency of Masaryk University [MUNI/J/0007/2021, MUNI/A/1298/2022]; Francqui Foundation for the Francqui Research Professor chai

Shear Strength of Copper Joints Prepared by Low Temperature Sintering of Silver Nanoparticles

In this work, mechanical properties of Cu-to-Cu joint samples prepared by low temperature sintering of Ag nanoparticle paste have been investigated. The silver nanopaste was prepared by a controlled thermal decomposition of an organometallic precursor. The as-synthesized Ag particles were spherical, with an average diameter of 8.5 nm. The Cu-to-Cu joint samples were made by placing a small amount of Ag nanopaste between two polished Cu plates and sintering at 150C, 200C, 220C and 350C in air. A normal load was applied to aid sintering. Mechanical properties were measured by imposing a uniform stress across the sample bond area and measuring the corresponding strain. The application of external load was found to have a positive effect on the material’s mechanical properties. Furthermore, interestingly high values of shear strength were observed.Byly zkoumány mechanické vlastnosti Cu-to-Cu spojů připravených nízkoteplotní sintrací pasty Ag nanočástic. Ag nanopasta byla připravena řízeným tepelným rozkladem organokovových prekurzorů. Syntetizované Ag NPs byly kulovité, o středním průměru 8,5 nm. Cu-to-Cu spoje byly vyrobeny umístěním malého množství Ag nanopasty mezi dvě leštěné Cu desky a sintrováním při 150C, 200C, 220C and 350C na vzduchu. Zatížení bylo použito na k podpoře sintrace. Mechanické vlastnosti byly měřeny stanovením napětí lomu a deformace. Bylo zjištěno, že aplikace vnějšího zatížení má pozitivní vliv na mechanické vlastnosti spoje

Ethanol dehydrogenation over copper-silica catalysts: From sub-nanometer clusters to 15 nm large particles

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 (sub-nanometer clusters), dry impregnation (A̅ = 3.4 nm; σ = 0.9 nm and particles up to 32 nm), strong electrostatic adsorption (A̅ = 3.1 nm; σ = 0.6 nm), and solvothermal hot injection followed by Cu particle deposition (A̅ = 4.0 nm; σ = 0.8 nm). All materials were characterized by ICP-OES, XPS, N2 physisorption, STEM-EDS, XRD, RFC N2O, and H2-TPR and tested in ethanol dehydrogenation from 185 to 325 °C. The sample prepared by hydrolytic sol–gel exhibited high 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). Importantly, 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.Web of Science1130109921098

Vanadium metal-organic frameworks derived VOx/Carbon nano-sheets and paperclip-like VOx/nitrogen-doped carbon nanocomposites for sodium-ion battery electrodes

In this work, vanadium metal-organic framework derived VOx/carbon and VOx/N-doped carbon nanocomposites are presented. The methodology introduced here is based on a novel polyol synthesis of vanadium metal-organic frameworks (MOFs) involving a microwave-assisted solvothermal reaction of vanadyl acetylacetonate with biphenyl-4,4'-dicarboxylic acid (Bpdc) and/or 2,2'-bipyridine-4,4'-dicarboxylic acid (NBpdc) in diethylene glycol (DEG) at the temperature of 230 degrees C. The V-based MOFs, labeled as V-Bpdc and V-NBpdc, were used as precursors for the preparation of VOx/carbon and VOx/N-doped carbon nanocomposites with unique sponge-like nano-sheet and paperclip-like morphology, respectively. The nanocomposites were obtained via thermal transformation of as-prepared vanadium MOFs in the argon atmosphere at 600 degrees C. The VOx/carbon sample consists of nano-sheets with the thickness 5-20 nm while the VOx/N-doped carbon paperclip-like nanocomposite has a rod diameter 35-70 nm. It was found that the approach reported here provides an effective and simple preparation pathway of carbon-based nanocomposites containing homogeneously distributed VOx species. Both V-MOFs and V-MOF-derived nanocomposites were characterized by the variety of physicochemical methods. In the following step, the obtained nanocomposites were investigated as electrode materials in sodium-ion batteries. Based on the obtained results, high electrochemical activities of VOx/carbon and VOx/N-doped carbon nanocomposites were evidenced. Particularly, in the case of VOx/N-doped carbon-based electrode, high capacity and low irreversible capacity were achieved. Therefore, reported materials are found to be promising candidates for electrode materials in sodium-ion batteries.FEKT-S-20-6206; INTER-TRANSFER LTT19001, RP/CPS/2020/006; Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT: LM2018110, LM2018127; Central European Institute of Technology, CEITEC; European Regional Development Fund, ERDF: CZ.1.05/2.1.00/19.0409; Masarykova Univerzita, MUMinistry of Education, Youth and Sports of the Czech Republic-Program NPU I [LO1504]; DKRVO [RP/CPS/2020/006]; INTER-TRANSFER [LTT19001]; Operational Program Research and Development for Innovations - European Regional Development Fund; national budget of the Czech Republic [CZ.1.05/2.1.00/19.0409]; BUT specific research program [FEKT-S-20-6206]; MEYS CR [LM2018127, LM2018110

Non-aqueous synthesis of homogeneous molybdenum silicate microspheres and their application as heterogeneous catalysts in olefin epoxidation and selective aniline oxidation

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(acetylacetonato)dioxomolybdenum and biphenyl-4,4′-dicarboxylic acid with 3-aminopropyltriethoxysilane under non-aqueous conditions. The as-prepared product was calcined at 500 °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 °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. © 2021 The Korean Society of Industrial and Engineering ChemistryRP/CPS/2020/006; Ministerstvo Školství, Mládeže a Tělovýchovy, MŠMT: LM2018110, LM2018127; Grantová Agentura České Republiky, GA ČR: GJ20-03636Y; Central European Institute of Technology, CEITEC; European Regional Development Fund, ERDF: CZ.1.05/2.1.00/19.040