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Povzetek: Graphene oxide (GO) is a standard precursor for the synthesis of porous yet densely packed, graphene-like structures in films with a thickness of several micrometers, which are useful for electrodes in various electrochemical devices, such as supercapacitors, as well as for various sensors. As-synthesized GO films exhibit inadequate electrical conductivity because of a large concentration of oxygen chemically bonded to graphene sheets. Heating of GO films in a non-oxidizing atmosphere will cause thermal decomposition of GO by desorption of carbon oxides, which will result in numerous defects in the sheets and partial collapsing of the sheets. An alternative is the treatment of GO films with non-equilibrium hydrogen plasma, which causes reduction rather than decomposition of the GO sheets. The scientific literature on approaches to reducing GO samples by treatment with hydrogen plasma is reviewed, the results are critically evaluated, and the correlations between the reduction efficiency and processing parameters are drawn. Paradoxically, larger discharge powers lead to worse results, both in terms of the remaining oxygen concentration and electrical properties. A feasible explanation for this paradox is radiation damage, which is likely caused by energetic photons or ions. The recommendation for further experiments in this tremendously promising niche is also presented.
Ključne besede: graphene oxide, hydrogen plasma, carbon materials
Objavljeno v DiRROS: 10.07.2026; Ogledov: 71; Prenosov: 67
Celotno besedilo (2,53 MB)
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Ključne besede: epoxy, graphene, MWCNTs, hybrid nanocomposites, wear, tensile strength
Objavljeno v DiRROS: 19.06.2026; Ogledov: 137; Prenosov: 96
Celotno besedilo (1,38 MB)
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Povzetek: Graphene-based composite materials have attracted much attention for a range of applications in various fields, including electronics, sensing, catalysis, energy storage and conversion. Single-step large-scale microwave plasma synthesis of graphene and nitrogen-doped graphene (N-graphene) composite materials has been demonstrated. The developed atmospheric pressure plasma method allows continuous synthesis of different graphene-based hybrids in a controllable and environmentally friendly manner. Control over the synthesis process, i.e., size, uniformity, surface distribution of the nanoparticles and graphene/N-graphene quality, was provided by adjusting plasma parameters and injection configuration. Protocols for the production of particular composites, i.e., graphene-MnO, N-graphene-MnO, N-graphene-MnS, and N-graphene-FexOy, have been established using methane and acetonitrile as precursors. A comprehensive physicochemical characterization of the produced composites was conducted using high-resolution transmission electron microscopy, scanning transmission electron microscopy, Raman spectroscopy, X-ray diffraction, and near-edge X-ray-absorption fine-structure and X-ray photoelectron spectroscopies.
Ključne besede: graphene composite, N-grapheme composite, microwave plasma, atmospheric pressure, scalable production
Objavljeno v DiRROS: 24.04.2026; Ogledov: 292; Prenosov: 196
Celotno besedilo (9,20 MB)
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Povzetek: In the present study, two types of graphene quantum dots (GQDs) were investigated: green-emitting (G-GQDs) and blue-emitting (B-GQDs). Physicochemical characterisation was performed using transmission electron microscopy (TEM), zeta potential, and hydrodynamic radius measurements to evaluate the morphology, particle size, aggregation behaviour, and colloidal stability of the GQDs in both water and cell culture medium. G-GQDs exhibited superior colloidal stability and more uniform dispersion than B-GQDs, whereas both types showed reduced aggregation and surface charge in cell culture medium due to protein corona formation. Toxicological characterisation was performed using an in vitro human hepatocellular carcinoma (HepG2) 3D spheroid model, with GQDs exposures up to 250 µg/mL (100 µg/cm2). Cytotoxicity was measured using the CellTiter-Glo luminometric assay, while genotoxicity was evaluated by the comet assay and flow cytometric analysis of γH2AX and phosphorylated histone H3 (p-H3) after 24 h of exposure. Both GQDs induced dose-dependent cytotoxic effects in HepG2 spheroids. At non-cytotoxic concentrations, a dose-dependent increase in DNA damage was observed, as determined by the comet assay. However, no evidence of DNA double-strand breaks (γH2AX) or elevated p-H3 levels was detected, suggesting the absence of clastogenic and aneugenic activity. The observed DNA single-strand breaks may be partly attributed to reactive oxygen species induction. These results indicate that, although GQDs induced cytotoxicity and single-strand DNA damage, no clear evidence of more severe genotoxic effects was observed under the tested conditions. Further studies are warranted to elucidate underlying mechanisms and comprehensively assess the safety profile of GQDs for biomedical applications.
Ključne besede: nanomaterials, graphene quantum dots, HepG2 spheroids, toxicity
Objavljeno v DiRROS: 19.03.2026; Ogledov: 451; Prenosov: 158
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Ključne besede: gamma irradiation, nanocomposite, graphene oxide, silver nanowire
Objavljeno v DiRROS: 26.02.2026; Ogledov: 458; Prenosov: 238
Celotno besedilo (1,35 MB)
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