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New Insights into Manganese Local Environment in MnS-1Nanocrystals
Alenka 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).
Found in: ključnih besedah
Summary of found: ...of manganese together with conventional and microwave-assisted hydrothermal synthesis paths on the formation of manganese...
Keywords: MnS-1 Nanocrystals, Mn XANES, EXAFS, zeolites, microwave-assisted hydrothermal synthesis
Published: 06.05.2019; Views: 2220; Downloads: 0
.pdf Fulltext (9,33 MB)

Synthesis of adsorbent-free ultrathin Bi2Se3 Topological Insulator Platelets and Its Inherent Surface Properties
Blaž Belec, Katja Ferfolja, Tanja Goršak, Nina Kostevšek, Sandra Gardonio, Mattia Fanetti, Matjaž Valant, 2019, published scientific conference contribution abstract

Found in: ključnih besedah
Summary of found: ...Bismuth selenide, topological insulator, hydrothermal synthesis, surface properties...
Keywords: Bismuth selenide, topological insulator, hydrothermal synthesis, surface properties
Published: 30.09.2019; Views: 2058; Downloads: 0
.pdf Fulltext (19,45 MB)

Inherent Surface Properties of Adsorbent-Free Ultrathin Bi2Se3 Topological Insulator Platelets
Blaž Belec, Ferfolja Katja, Goršak tanja, Kostevšek Nina, Gardonio Sandra, fanetti mattiea, 2019, original scientific article

Found in: ključnih besedah
Summary of found: insulator inherent surface properties Localized surface plasmon resonance hydrothermal synthesis...
Keywords: Topological insulator inherent surface properties Localized surface plasmon resonance hydrothermal synthesis
Published: 13.12.2019; Views: 2052; Downloads: 65
.pdf Fulltext (2,11 MB)

Natural precursor based hydrothermal synthesis of sodium carbide for reactor applications
SWAPNA MOHANACHANDRAN NAIR SINDHU, 2017, original scientific article

Abstract: Carbides are a class of materials with high mechanical strength and refractory nature which finds a wide range of applications in industries and nuclear reactors. The existing synthesis methods of all types of carbides have problems in terms of use of toxic chemical precursors, high-cost, etc. Sodium carbide (Na2C2) which is an alkali metal carbide is the least explored one and also that there is no report of low-cost and low-temperature synthesis of sodium carbide using the eco-friendly, easily available natural precursors. In the present work, we report a simple low-cost, non-toxic hydrothermal synthesis of refractory sodium carbide using the natural precursor—Pandanus. The formation of sodium carbide along with boron carbide is evidenced by the structural and morphological characterizations. The sample thus synthesized is subjected to field emission scanning electron microscopy (FESEM), x-ray powder diffraction (XRD), ultraviolet (UV)—visible spectroscopy, Fourier transform infrared spectroscopy (FTIR), Raman, and photoluminescent (PL) spectroscopic techniques.
Found in: ključnih besedah
Keywords: sodium carbide, pandanus, hydrothermal synthesis, porous materials
Published: 30.06.2022; Views: 117; Downloads: 0
.pdf Fulltext (2,57 MB)

Concentration-dependent thermal duality of hafnium carbide nanofluid for heat transfer applications
V. Gokul, Mohanachandran Nair Sindhu Swapna, Vimal Raj, H. V. Saritha Devi, Sankaranarayana Iyer Sankararaman, 2021, original scientific article

Abstract: he mode mismatch dual-beam thermal lens technique is a sensitive tool for studying the nanofuids’ thermal difusivity in thermal engineering. The work reports the low-temperature green synthesis of hafnium carbide (HfC) using rice four as a natural carbon precursor and its potential in heat transfer nanofuids by studying the concentration-dependent thermal difusivity. The structure characterisations confrm the formation of HfC, whose refractory nature is revealed through the high thermal stability observed in the thermogravimetric analysis. The Tauc plot analysis shows direct bandgap energy of 2.92 eV. The fuorescence study suggests bluish-pink emission with CIE coordinates (0.271, 0.263). The existence of the critical concentration of HfC in the nanofuid decides its suitability for heat transfer or heat trap applications indicating a concentration-dependent thermal duality. Thus, the study is signifcant as it overcomes the major drawbacks of the existing methods of the synthesis of refractory HfC, using toxic chemical and costly equipment for heat transfer applications.
Found in: ključnih besedah
Summary of found: ...hafnium carbide, hydrothermal synthesis, rice flour, thermal lens spectroscopy...
Keywords: hafnium carbide, hydrothermal synthesis, rice flour, thermal lens spectroscopy
Published: 04.07.2022; Views: 69; Downloads: 0
.pdf Fulltext (1,50 MB)

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