Advanced Materials Research Vols. 306-307

Abstract: Anatase nano titanium oxide was synthesized with Ti(SO₄)₂ as titanium source and stronger ammonia water as precipitant using the hydrothermal method. The samples were characterized by XRD, SEM, TEM and UV-VIS. The results showed that the influence of the increase of the reaction time on as-prepared anatase nano titanium oxide was not obvious when stronger ammonia water was not added to Ti(SO₄)₂ solution. Anatase nano titanium oxide became small markedly under the same conditions when stronger ammonia water was added to Ti(SO₄)₂ solution. Anatase nano titanium oxide of about 20 nm in the diameter was obtained for 48 h with pH=9 at 240 °C by the hydrothermal method. That the size of Anatase nano titanium oxide particles became small was propitious to the blue shift of their absorption peak.

Abstract: Highly luminescent CdSe/Cd_xZn_1-xS core-shell quantum dots (QDs) were synthesized using CdSe cores with the size range of 2 to 5 nm in diameter through a facile organic route. The CdSe cores were prepared by using trioctylphosphine oxide and hexadecylamine as capping agents for the purpose of getting spherical morphology. The cores were coated with an alloy shell to decrease the lattice mismatch between the core and the shell through a facile organic approach. The QDs exhibited tunable photoluminescence (PL) up to 654 nm, narrow PL spectra (less than 40 nm for full width at half maximum) and high PL efficiency. Such properties make the core-shell QDs as a good candidate for further applications.

Abstract: α-Ni(OH)₂ peonylike structures assembled from nanosheets with thickness of 10nm were successfully synthesized via a hydrothermal method. The corresponding NiO peonylike structures with similar morphology to the α-Ni(OH)₂ precursor were also be fabricated by thermal decomposition of the as-synthesized α-Ni(OH)₂ at 350°C for 2 h in air. Samples are thoroughly characterized by field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectrum, Brunauer-Emmett-Tellermethod (BET), and thermogravimetric analysis (TGA). The BET surface area for α-Ni(OH)₂ and NiO are 36.0m²/g and 120.2 m²/g, respectively.

Abstract: Carbon/carbon core/shell nanofibers with length up to several micrometres have been prepared by co-pyrolysis of tetrahydrofuran and ferrocene in a stainless steel autoclave at 600 °C. The diameter of carbon core is ~10 nm, and the thickness of carbon shell is ~20 nm. It is found that the graphene layers of carbon core are perpendicular to the ones of carbon shell in stacking orientation. Comparative experiments confirm that the metallic iron catalysts, originating from the decomposition of ferrocene, are responsible for the formation of nanofibers. When the ferrocene is absence, only solid carbon spheres are observed. Moreover, hollow hexapod-like carbon materials can be obtained with water introduced into reaction system.

Abstract: A conductive glassy carbon ceramic composite electrode (GCCE) comprised of multi-walled carbon nanotubes (MWNTs) and glassy carbon microparticles in an organically modified silicate matrix was fabricated using a sol-gel method. The electrode thus prepared exhibits electrocatalytic behavior to the reduction of nitrite and facilitates the detection of nitrite at an applied potential of 0.0 V. A linear range from 2.5×10^-5 to 3×10^-3 M for the detection of sodium nitrite has been observed at the composite electrode with a sensitivity of 9.6 μA/mM and a detection limit of 9×10^-6 M based on a signal-to-noise ratio of 3.

Abstract: Carbon-nanotube(CNT)-modified glassy carbon electrodes exhibiting strong electrocatalytic response toward nitrite are described. Cyclic voltammetry and differential pulse voltammetry are used to investigate the electrocatalytic property of CNT-modified glassy carbon electrode toward the reduction of nitrite. The modified electrode could be used for nitrite sensing.

Abstract: Vanadium dioxides (VO₂) is synthesized by hydrothermal method. In this process,V₂O₅ powder is used as raw materials,cetyltrimethylammonium bromide (CTAB) is used as template and different alcohols such as methanol, ethanol, propanol and butanol are used as reductants. X-ray diffraction (XRD) and scanning electron microscopy (SEM) are used to test the properties of VO₂ nanoparticles. The results show that VO₂(B) nano-particles were succsessfully synthesized under the conditions of thermal reduction temperature 180°C, reaction time 24h and drying temperature 60°C. The variety of alcoholic reducing agents plays an important role in the structure and morphology of the product VO₂(B), which relates closly to the electric properties of materials.

Abstract: Novel organic –inorganic nanocomposite hybrid materials have been prepared by a sol-gel process. Tetraethoxysilane (TEOS) was used as inorganic source. Polyurethane acrylate (PUA) was the organic segment. 3-(trimethoxysilyl)propyl methacrylate (KH-570) was used as both a secondary inorganic source and a silane coupling agent to improve the compatibility of the organic and inorganic phases. X-ray diffraction indicates that silica was equally dispersed in polymer matrix. Furthermore, silica and polymer formed interpenetrating polymer network. Thermal property of the hybrid materials were checked by TGA study.

Abstract: In this paper, the Ti-O-Compound nanobelts from commercial TiO₂ (annatase phase) were synthesized via the alkali-hydrothermal process. The as-synthesized nanobelts are sodium titanate, hydrogen titanate and anatase with general formula Na₂Ti₃O₇, H₂Ti₃O₇ and TiO₂, respectively. The nanobelts are characterized by Thermogravimetric/Differential Thermal Analysis (TG/DTA), X-ray Diffraction (XRD), Infrared Spectra (IR) and Scanning Electron Microscope (SEM) apparatuses. The characterization indicates that the nanobelts with typical widths of 50 to 200 nm, thicknesses of 20 to 50 nm, and up to a few millimeters in length. The conversion mechanisms between the layer titanate and anatase of nanobelts have been discussed in this study.

Abstract: In the solutions which are prepared by mixing zinc nitrate hexahydrate, strong ammonia and methenamine in water bath at 90 Centigrade, lamellate and granular zinc oxide films have grown on different substrates such as B270 glass, glass based PAA films, pure aluminum foil and aluminum based PAA films. Films microstructures were characterized by scanning electron microscope (SEM). The influences of substrate and pH on the films microstructure were analyzed. Results reflect that: Ammonia plays an important role in the growing competition of grainy crystal; the more concentration of ammonia, the more zinc oxide crystals grow into granular. Because of the high specific area and adsorption capacity, lacunaris zinc oxide films have great application perspective in gas sensor, catalyzed sorption and biochemistry.