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Povzetek: We report the synthesis of a ceria-based catalyst support containing embedded magnetic iron–oxide nanoparticles (IONPs) that enable heating under a high-frequency alternating magnetic field. The ≈11 nm IONPs, synthesized by co-precipitation of Fe2+/Fe3+ ions at room temperature, were coarsened to ≈18 nm through subsequent hydrothermal treatment at 120 ◦C and then coated with a ≈2 nm silica layer. The catalyst support was prepared by depositing nanocrystalline ceria (CeO2) onto the IONPs via controlled precipitation of Ce3+ ions in the presence of hexamethylenetetramine (HMTA) in aqueous suspension. When deposited directly on the iron oxide, ceria formed small agglomerates of ≈10 nm octahedral nanocrystallites, whereas deposition on silicacoated IONPs produced a homogeneous 3–6 nm-thick shell composed of ≈3 nm globular crystallites. Special attention was given to elucidating the mechanism of shell formation. The magnetic catalyst was obtained by precipitating Ru nanoparticles (1–2 nm) onto the ceria support. Morpho-structural characterization was performed by XRD, TEM, and aberration-corrected STEM. Static and dynamic magnetization measurements at room temperature were used to assess the magnetic and heating performance. At low field amplitudes (<15 mT), catalysts prepared with IONPs of both sizes exhibited similar specific absorption rates, whereas at higher amplitudes the larger IONPs demonstrated superior heating efficiency. The catalytic performance was demonstrated in the magnetically heated hydrogenation of the bio-based compound 5-(hydroxymethyl)furfural to 2,5-bis (hydroxymethyl)furan, showing high activity, 100 % selectivity, and excellent stability upon recycling.
Ključne besede: nanotechnology, catalyst synthesis, ceria, magnetic nanoparticles, catalysis by magnetic heating, biomass valorisation, transmission electron microscopy
Objavljeno v DiRROS: 14.01.2026; Ogledov: 44; Prenosov: 24
Celotno besedilo (11,51 MB)
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Povzetek: Temperature sensing at the micro- and nanoscale remains a significant challenge due to the limitations of conventional techniques in spatial resolution and invasiveness. Here, we report the development of luminescent, temperature-sensitive coatings and nanoparticles based on a newly synthesized europium (Eu) complex integrated into a composite poly(methyl methacrylate)-siloxane-silica (PMMA-siloxane silica) matrix. The Eu complex, identified as the most promising candidate among three lanthanide complexes, was functionalized with silyl ethers via copper-catalyzed azide-alkyne cycloaddition and successfully incorporated into thin PMMA-siloxane silica films on glass surfaces and within silica nanoparticles. These materials exhibited strong thermal responsiveness, chemical stability, and suitability for high-resolution temperature sensing. Furthermore, Eu-loaded silica nanoparticles showed a distinct fluorescent signal and multiplexing capability in live-cell confocal microscopy and were internalized by lung epithelial cells (LA-4 cell line), highlighting their potential as bioimaging probes for localized intracellular temperature sensing. Although some photobleaching was observed under prolonged excitation, the materials demonstrated sufficient chemical and mechanical stability, making them promising for luminescent temperature sensing and live-cell imaging. These results establish the developed Eu-based hybrid materials as robust, non-invasive luminescent probes for high-resolution thermal sensing and cellular imaging.
Ključne besede: temperature sensing, silica nanoparticles, europium complex, photostability
Objavljeno v DiRROS: 26.09.2025; Ogledov: 300; Prenosov: 128
Celotno besedilo (4,72 MB)
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Ključne besede: hybrid composites, glass-jute fiber, eggshell nanoparticles, sustainable reinforcement, bio-inspired nanocomposites, waste valorization
Objavljeno v DiRROS: 23.06.2025; Ogledov: 585; Prenosov: 275
Celotno besedilo (1,43 MB)
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Povzetek: Gold nanoparticles (AuNPs) were synthesised using ultrasonic spray pyrolysis (USP) with the addition of polyvinylpyrrolidone (PVP) as a stabilising agent and subsequently dried via lyophilisation. The resulting dried AuNPs were redispersed in ethanol and homogenised to ensure uniform dispersion. This AuNP dispersion was then deposited onto a ceramic substrate - aluminum oxide (Al2O3) - using plasma jet printing. Comprehensive characterisation of the dispersion, AuNPs, and the resulting printed lines was performed using the following methods: inductively coupled plasma optical emission spectroscopy (ICP-OES), scanning electron microscopy (SEM), transmission electron microscopy (TEM), selected area electron diffraction (SAED), scanning transmission electron microscopy (STEM), energy dispersive X-ray spectroscopy (EDS), ultraviolet-visible spectroscopy (UV–Vis), dynamic light scattering (DLS), measurements of dispersion viscosity and printed line roughness. ICP-OES confirmed consistent gold content in the AuNP dispersion, while the SEM and EDS analyses revealed predominantly spherical AuNPs with minimal aggregation and similar size distributions. TEM, SAED, and STEM/EDS confirmed that the crystalline structure and elemental composition of the AuNPs had diverse morphologies and strong gold signals. The UV–VIS, DLS, and zeta potential measurements indicated moderate colloidal stability, and thermogravimetric analysis (TGA) verified the AuNPs dispersion’s composition. The AuNP dispersion exhibited thixotropic behaviour favourable for printing applications, while confocal microscopy confirmed smooth, uniform printed traces, with an average surface line roughness of 1.65 μm. The successful use of plasma printing with the AuNP dispersion highlights its potential for functional material applications in electronics.
Ključne besede: gold nanoparticles, ultrasonic spray pyrolysis, dispersion, plasma jet printing
Objavljeno v DiRROS: 19.06.2025; Ogledov: 574; Prenosov: 327
Celotno besedilo (5,02 MB)
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Povzetek: The study aimed to develop a superhydrophobic coating on the aluminium alloy 2024-T3 surface. The desired surface roughness and low surface energy were achieved with SiO2 nanoparticles, synthesised via the Stöber method and modified with alkyl silane (AS) or perfluoroalkyl silane (FAS). To enhance particle adhesion to the alloy substrate, nanoparticles were incorporated into a hybrid sol–gel coating composed of tetraethyl orthosilicate, methyl methacrylate, and 3-methacryloxypropyl trimethoxysilane. The coated substrates were characterised using field emission scanning and transmission electron microscopy with energy-dispersive spectroscopy for surface topography, nanoparticle size distribution, composition, and coating thickness. The corrosion resistance of the coatings on AA2024-T3 was evaluated in a 0.1 M NaCl solution using electrochemical impedance spectroscopy. The synthesised SiO2 nanoparticles had an average size between 25 and 35 nm. The water contact angles on coated aluminium surfaces reached 135° for SiO2 + AS and 151° for SiO2 + FAS. SiO2 + FAS, indicating superhydrophobic properties, showed the most uniform surface with the most consistent size distribution of the SiO2 nanoparticles. Incorporation of nanoparticles into the hybrid sol–gel coating further improved particle adhesion. The ~2 µm-thick coating also demonstrated efficient barrier properties, significantly enhancing corrosion resistance for over two months under the test conditions.
Ključne besede: nanoparticles, hybrid sol–gel, adhesion
Objavljeno v DiRROS: 15.04.2025; Ogledov: 851; Prenosov: 346
Celotno besedilo (11,65 MB)
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