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Silicon carbide (SiC) was prepared by carbothermal reduction of a crystalline-layered sodium silicate (δ-Na2Si2O5)/carbon nanocomposite (LCN), which contained a stacked carbon film embedded with cobalt between the silicate layers. Subsequent sintering of this mixture for 3 h at 1000–1350°C resulted in the formation of graphitic carbon and SiC. Meanwhile, sintering without a cobalt catalyst resulted in the formation of graphitic carbon, regardless of the temperature. The use of a cobalt catalyst allowed the formation of a pure SiC phase at 1350°C. The formed SiC had an irregular worm-like morphology, with a particle size of ~5 µm. The Brunauer-Emmett-Teller surface areas of graphitic carbon and SiC were 28–150 and ~7.0 m2/g, respectively. We concluded that graphite and SiC were produced at this low sintering temperature because of the cobalt catalyst, which facilitated nanomixing of carbon and SiO2 by sandwiching the carbon films between the silicate layers. [ABSTRACT FROM AUTHOR]

Carboxylated-graphene–Mn2O3 (G-COOMn) nanocomposites were grown as Mn2O3 nanowires on graphene sheets by a one-step thermal method using graphene oxide–COOH (G-COOH) and Mn(NO3)2. Graphene oxide (G) was prepared by the Hummers method by using graphite flakes as a starting material. G-COOH sheets were synthesized using G and chloroacetic acid (Cl–CH2–COOH). G, G-COOH, and G-COOMn were characterized by X-ray diffraction, atomic force microscopy, scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, 13C-nuclear magnetic resonance, and Raman spectroscopy. The electrochemical properties of the fabricated G-COOMn supercapacitor were investigated by cyclic voltammetry, electrochemical impedance spectroscopy, and galvanostatic charge–discharge tests. The obtained results showed that the asymmetric supercapacitor had electrochemical capacitance performance within the potential range 0–0.7 V. The supercapacitor delivered a specific capacitance of ∼300 F g−1 at a current density of 50 mA cm−2. The method used in this work provides an easy and straightforward approach for depositing Mn2O3 nanowires on graphene sheets and may be readily extended to the preparation of other classes of hybrids based on G sheets for use in specific technological applications. [ABSTRACT FROM AUTHOR]

Abstract: Titanosilicate was modified by interlayer surface silylation using octyltriethoxysilane (OTES) and dodecylamine (DDA) in ethanol without a pre-swelling step. The introduction of silyl groups into the interlayer region was confirmed by XRD, FT-IR, RAMAN, SEM, TGA, 29Si NMR and TEM. DDA acts as a gallery expander and silylation catalyst. The evaporation of ethanol from the dispersion yields well-ordered silylation. Layered titanosilicate silicate with large basal spacings between 2.95 and 3.87nm were investigated. The layered structures of the silylated products were confirmed by swelling behavior upon attachment of alkylsilyl groups. Solid-state 29Si MAS NMR of the silylated samples showed Q3 and Q4 signals as well as T2 signals. The increase in the relative intensity of Q4 for Q3 and the appearance of a T2 signal was attributed to the grafting of OTES to the interlayer surface silanol groups. This method provides a promising route for the preparation of new functional nanomaterials to bond a variety of functional groups to the interlayer surface of layered materials. [Copyright &y& Elsevier]

Abstract: H+-titanosilicate (H4Ti2Si8O22 ·4H2O), formed by proton ion exchange of layered titanosilicate JDF-L1 (Na4Ti2Si8O22 ·4H2O) produced intercalation compounds in DDA (dodecylamine)–TEOS (tetraethylorthosilicate) solution. H+-titanosilicate/DDA/TEOS intercalation compounds rapidly hydrolyzed in pure water to form siloxane-pillared H+-titanosilicates. Calcination of siloxane-pillared H+-titanosilicates for 5h at 500°C in air resulted in the formation of mesoporous silica-pillared H+-titanosilicate (SPT) derivatives. SPT derivatives exhibited refractions corresponding to a basal spacing of 4.16–4.32nm, a uniform pore size of 2.8–3.4nm, and a large surface area of 535–618m2/g. The structures and physical properties of SPT derivatives remained stable after heating for 5h at 700°C in air. These results indicate that DDA molecules have a decisive role in pore formation within SPT derivatives, because they act as a base catalyst and as a template, like surfactant micelles, during the hydrolysis of TEOS. [Copyright &y& Elsevier]

Abstract: The new ion-selective electrodes (ISEs) based on salphenH2 derivatives such as N,N′-(propylenedioxy)benzenebis(salicylideneimine) L 1 and N,N′-4,5-(propylenedioxy)benzenebis(3,5-di-tert-butylsalicylideneimine) L 2 as cation carriers are developed for a uranyl ion. The combination of these new ionophores with tris(2-ethylhexyl)phosphate (TEHP) as a plasticizer particularly shows near Nernstian slope in the wide concentration range (1.0×10−6 to 1.0×10−2 M) of UO2 2+ and is observed well in the pH range from 1.0 to 5.0 with a response time less than 20s. Since the employed ionophores were confirmed to form well-defined stable 1:1 complexes with UO2 2+, the observed high selectivity for a uranyl ion over the other cations was attributed to the selective complexation as well as the lipophilic behavior of these ligands especially for L 2 . The proposed electrodes offered practically low detection limit of 6.5×10−7 M and reasonably good end-points within experimental error were obtained when the sensor was used as an indicator electrode for the potentiometric titration. [Copyright &y& Elsevier]

Mesoporous silica (MSPN12) was prepared by nonionic surfactant micelle–templated gelation of sodium silicate (Na2SiO3) and fluorosilicic acid (H2SiF6) in aqueous solution, characterized by a range of instrumental techniques, and tested as a support for Ni and Rh catalysts in the partial oxidation of methane (POM). Calcined and sintered MSPN12 exhibited well-defined d00l-spacings (3.5–4.39 nm), narrow pore distributions (2.4–3.1 nm), and large specific surface areas (552–1,246 m2 g−1), and was found to be highly thermally stable. Microscopic imaging revealed that MSPN12 comprised spherical particles with a uniform diameter of ~0.7 µm, with each particle featuring firm and regular honeycomb-type pores. MSPN12-loaded Ni and Rh maintained stable POM activity at 700 °C during almost 100 h on stream, which were comparable to those for the commercial Rh(5)/Al2O3 catalyst in terms of methane conversion and H2 formation selectivity. Thus, the combination of structural stability and favorable physicochemical properties resulted in good POM performance. [ABSTRACT FROM AUTHOR]

Mesoporous silica (MSPN12) was prepared by nonionic surfactant micelle–templated gelation of sodium silicate (Na2SiO3) and fluorosilicic acid (H2SiF6) in aqueous solution, characterized by a range of instrumental techniques, and tested as a support for Ni and Rh catalysts in the partial oxidation of methane (POM). Calcined and sintered MSPN12 exhibited well-defined d00l-spacings (3.5–4.39 nm), narrow pore distributions (2.4–3.1 nm), and large specific surface areas (552–1,246 m2 g−1), and was found to be highly thermally stable. Microscopic imaging revealed that MSPN12 comprised spherical particles with a uniform diameter of ~0.7 µm, with each particle featuring firm and regular honeycomb-type pores. MSPN12-loaded Ni and Rh maintained stable POM activity at 700 °C during almost 100 h on stream, which were comparable to those for the commercial Rh(5)/Al2O3 catalyst in terms of methane conversion and H2 formation selectivity. Thus, the combination of structural stability and favorable physicochemical properties resulted in good POM performance. [ABSTRACT FROM AUTHOR]

Silicon carbide (SiC) was prepared by carbothermal reduction of a crystalline-layered sodium silicate (δ-Na 2 Si 2 O 5 )/carbon nanocomposite (LCN), which contained a stacked carbon film embedded with cobalt between the silicate layers. Subsequent sintering of this mixture for 3 h at 1000-1350°C resulted in the formation of graphitic carbon and SiC. Meanwhile, sintering without a cobalt catalyst resulted in the formation of graphitic carbon, regardless of the temperature. The use of a cobalt catalyst allowed the formation of a pure SiC phase at 1350°C. The formed SiC had an irregular worm-like morphology, with a particle size of ~5 µm. The Brunauer-Emmett-Teller surface areas of graphitic carbon and SiC were 28-150 and ~7.0 m 2 /g, respectively. We concluded that graphite and SiC were produced at this low sintering temperature because of the cobalt catalyst, which facilitated nanomixing of carbon and SiO 2 by sandwiching the carbon films between the silicate layers.