21. Solvothermal synthesis of iron phosphides and their application for efficient electrocatalytic hydrogen evolutionTakwa Chouki, Manel Machreki, Saim Emin, 2020, original scientific article Abstract: Abstract
In this paper, we present a solvothermal synthesis of iron phosphide electrocatalysts using a triphenylphosphine (TPP) precursor. The synthetic protocol generates Fe2P phase at 300 °C and FeP phase at 350 °C. To enhance the catalytic activities of obtained iron phosphide particles heat-treatments were carried out at elevated temperatures. Annealing at 500 °C under reductive atmosphere induced structural changes in the samples: (i) Fe2P provided a pure Fe3P phase (Fe3P−500 °C) and (ii) FeP transformed into a mixture of iron phosphide phases (Fe2P/FeP−500 °C). Pure Fe2P films was prepared under argon atmosphere at 450 °C (Fe2P−450 °C). The electrocatalytic activities of heat-treated Fe2P−450 °C, Fe3P−500 °C, and Fe2P/FeP−500 °C catalysts were studied for hydrogen evolution reaction (HER) in 0.5 M H2SO4. The HER activities of the iron phosphide catalyst were found to be phase dependent. The lowest electrode potential of 110 mV vs. a reversible hydrogen electrode (RHE) at 10 mA cm−2 was achieved with Fe2P/FeP−500 °C catalyst.
Keywords: Solvothermal synthesis, Iron phosphide, Electrocatalyst, Hydrogen evolution, Overpotential
Published in RUNG: 20.07.2020; Views: 2659; Downloads: 0
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22. X-ray absorption spectroscopy set-up for unstable gases: A study of 5p HydridesRobert Hauko, Jana Padežnik Gomilšek, Alojz Kodre, Iztok Arčon, 2020, original scientific article Abstract: An absorption cell is constructed for x-ray absorption spectroscopy of reactive, unstable or hazardous gases at
room temperature. In conjunction with in-situ micro-synthesis technique relying on handling the gas in syringes
it enabled a first measurement of x-ray absorption spectra in the region of K and L edges for the series of hydrides
of 5p elements (SnH4, SbH3, TeH2, HI). The signal-to-noise ratio above 103 was achieved, whereby fine detail is
discerned in the spectra, in particular the small sharp features above each absorption edge, testifying of coexcitations
of outer electrons in the core photoeffect.
Keywords: X-ray absorption spectroscopy
Micro-synthesis absorption cell
Gaseous hydrides
Multielectron photoexcitations
Published in RUNG: 10.02.2020; Views: 3446; Downloads: 0
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24. Synthesis of adsorbent-free ultrathin Bi2Se3 Topological Insulator Platelets and Its Inherent Surface PropertiesBlaž Belec, Katja Ferfolja, Tanja Goršak, Nina Kostevšek, Sandra Gardonio, Mattia Fanetti, Matjaž Valant, 2019, published scientific conference contribution abstract Keywords: Bismuth selenide, topological insulator, hydrothermal synthesis, surface properties
Published in RUNG: 30.09.2019; Views: 3328; Downloads: 0
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25. New Insights into Manganese Local Environment in MnS-1NanocrystalsAlenka Ristić, Matjaž Mazaj, Iztok Arčon, Nina Daneu, Nataša Zabukovec Logar, Roger Glaser, Nataša Novak Tušar, 2019, original scientific article Abstract: Manganese plays an important role in redox catalysis using zeolites as inorganic support materials, but the formation of the preferred redox manganese species (framework or extraframework) is still not well understood. Herein, the influence of the amount of manganese together with conventional and microwave-assisted hydrothermal synthesis paths on the formation of manganese species within the zeolite silicalite-1 (S-1) with MFI structure was investigated. It was found out that both synthesis procedures led to the formation of framework and extraframework manganese species, but in different molar ratios. However, the conventional synthesis procedure with all Mn/Si molar ratios generates more framework Mn in comparison to the microwave procedure. Additionally, the diminution of the zeolite crystals to nanoscale from 100 to 200 nm was achieved via the conventional procedure for the first time. UV–vis, Raman, and X-ray absorption spectroscopic analyses revealed different local environments of manganese: Mn3+ incorporated into the silicalite-1 framework as “framework manganese” and Mn2+/3+ present as “extraframework manganese” (Mn2O3, Mn3O4). TEM reveals the presence of Mn3O4 nanorods. Both framework manganese and extraframework manganese exhibit good catalytic activity for styrene epoxidation. Catalytic results suggest that, in oxidation reactions of hydrocarbons, framework manganese is more active at lower Mn contents (Mn/Si < 0.015), whereas extraframework manganese is more active at higher loadings (Mn/Si > 0.015).
Keywords: MnS-1 Nanocrystals, Mn XANES, EXAFS, zeolites, microwave-assisted hydrothermal synthesis
Published in RUNG: 06.05.2019; Views: 3353; Downloads: 0
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28. Pursuing the stabilisation of crystalline nanostructured magnetic manganites through a green low temperature hydrothermal synthesisArianna Minelli, Paolo Dolcet, Stefano Diodati, Sandra Gardonio, Claudia Innocenti, Denis Badocco, Stefano Gialanella, Paolo Pastore, Luciano Pandolfo, Andrea Caneschi, Angela Trapanati, Silvia Gross, 2017, original scientific article Abstract: A quick, easy and green water-based synthesis protocol involving coprecipitation of oxalates combined with hydrothermal treatment resulted in the crystallisation of nanostructured manganites at a relatively low temperature (180 °C). The subcritical hydrothermal approach was shown to play a key role in stabilising phases which are generally achieved at much higher temperatures and under harsher conditions, thus disclosing an exciting alternative for their synthesis. Through this mild wet chemistry approach, the compounds CuMnO2, ZnMn2O4 and ZnMnO3 were synthesised as nanocrystalline powders. Noticeably, the optimised route proved to be effective in stabilising the exotic polymorph cubic spinel ZnMnO3 in pure form. This is particularly notable, as very few records concerning this compound are available in the literature. The compounds were fully characterised from compositional, structural, morphological and magnetic points of view.
Keywords: nanostructured manganites, low temperature wet chemistry synthesis
Published in RUNG: 28.03.2017; Views: 4276; Downloads: 0
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29. One-pot synthesis of biocompatible silver nanoparticle composites from cellulose and keratin: characterization and antimicrobial activityChieu Ding Tran, Franja Prosenc, Mladen Franko, Gerald Benzi, 2016, original scientific article Abstract: A novel, simple method was developed to synthesize biocompatible composites containing 50% cellulose (CEL) and 50% keratin (KER) and silver in the form of either ionic (Ag+) or Ag0 nanoparticle (Ag+NPs or Ag0NPs). In this method, butylmethylimmidazolium chloride ([BMIm+Cl-]), a simple ionic liquid, was used as the sole solvent and silver chloride was added to the [BMIm+Cl-] solution of [CEL+KER] during the dissolution process. The silver in the composites can be maintained as ionic silver (Ag+) or completely converted to metallic silver (Ag0) by reducing it with NaBH4. Results of spectroscopy (Fourier-transform infrared (FTIR), X-ray diffraction (XRD)) and imaging (scanning electron microscope (SEM)) measurements confirm that CEL and KER remain chemically intact and homogeneously distributed in the composites. Powder X-ray diffraction (XRD) and SEM results show that the silver in the [CEL+KER+Ag+] and [CEL+KER+Ag0] composites is homogeneously distributed throughout the composites in either Ag+ (in the form of Ag2O nanoparticles (NPs)) or Ag0NPs form with size of (9 ± 1) nm or (27 ± 2) nm, respectively. Both composites were found to exhibit excellent antibacterial activity against many bacteria including Escherichia coli, Staphylococus aureus, Pseudomonas aeruginosa, methicillin resistant Staphylococus aureus (MRSA), vancomycin resistant Enterococus faecalis (VRE). The antibacterial activity of both composites increases with the Ag+ or Ag0 content in the composites. More importantly, for the same bacteria and the same silver content, [CEL+KER+Ag0] composite exhibits relatively greater antimicrobial activity against bacteria compared to the corresponding [CEL+KER+Ag+] composite. Experimental results confirm that there was hardly any Ag0NPs release from the [CEL+KER+Ag0NPs] composite, and hence its antimicrobial activity and biocompatibility is due, not to any released Ag0NPs but rather entirely to the Ag0NPs embedded in the composite. Both Ag2ONPs or Ag0NPs were found to be toxic to human fibroblasts at higher concentration (>0.72 mmol), and that for the same silver content, [CEL+KER+Ag2ONPs] composite is relatively more toxic than [CEL+KER+Ag0NPs] composite. As expected, by lowering the Ag0NPs concentration to 0.48 mmol or less, the [CEL+KER+Ag0NPs] composite can be made biocompatible while still retaining its antimicrobial activity against bacteria such are E. coli, S. aureus, P. aeruginosa, MRSA, VRE. These results together with our previous finding that [CEL+KER] composites can be used for controlled delivery of drugs such as ciprofloxacin clearly indicate that the [CEL+KER+Ag0NPs] composite possess all required properties for successfully used as high performance dressing to treat chronic ulcerous infected wounds.
Keywords: Celulose, Keratin, Cmposites, Biocompatible, Ag nanoparticles, one-pot synthesis, Antibacterial, Antiviral
Published in RUNG: 28.11.2016; Views: 5072; Downloads: 0
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30. Synthesis, Structure and Antimicrobial Property of Green Composites from Cellulose, Wool, Hair and Chicken FeatherChieu Tran, Franja Prosenc, Mladen Franko, Gerald Benzi, 2016, original scientific article Abstract: Novel composites between cellulose (CEL) and keratin (KER) from three different sources (wool, hair and chicken feather) were successfully synthesized in a simple one-step
process in which butylmethylimidazolium chloride (BMIm+Cl-), an ionic liquid, was used as the sole solvent. The method is green and recyclable because [BMIm+Cl-] used was recovered for reuse. Spectroscopy (FTIR, XRD) and imaging (SEM) results confirm that CEL and KER remain chemically intact and homogeneously distributed in the composites. KER retains some of its secondary structure in the composites. Interestingly, the minor differences in the structure of
KER in wool, hair and feather produced pronounced differences in the conformation of their corresponding composites with wool has the highest α-helix content and feather has the lowest content. These results correlate well with mechanical and antimicrobial properties of the composites. Specifically, adding CEL into KER substantially improves mechanical strength of [CEL+KER] composites made from all three different sources, wool, hair and chicken feathers (i.e., [CEL+wool], [CEL+hair] and [CEL+feather]. Since mechanical strength is due to CEL, and CEL has only random structure, [CEL+feather] has, expectedly, the strongest mechanical property because feather has the lowest content of α-helix. Conversely, [CEL+wool] composite
has the weakest mechanical strength because wool has the highest α-helix content. All three composites exhibit antibacterial activity against methicillin resistant S. aureus (MRSA). The antibacterial property is due not to CEL but to the protein and strongly depends on the type of the
keratin, namely, the bactericidal effect is strongest for feather and weakest for wool. These results together with our previous finding that [CEL+KER] composites can control release of drug such as ciprofloxacin clearly indicate that these composites can potentially be used as wound dressing.
Keywords: Green synthesis, Ionic liquid, Keratin, Antibacteria, Wound dressing
Published in RUNG: 08.06.2016; Views: 4479; Downloads: 0
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