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Effect of Graphene Oxide on the Properties of Its Composite with Polyaniline

Graphene oxide, a single layer of graphite oxide (GO), has been used to prepare graphene oxide/polyaniline (PANI) composite with improved electrochemical performance as supercapacitor electrode by in situ polymerization using a mild oxidant. The composites are synthesized under different mass ratios, using graphite as start material with two sizes: 12 500 and 500 mesh. The result shows that the morphology of the prepared composites is influenced dramatically by the different mass ratios. The composites are proposed to be combined through electrostatic interaction (doping process), hydrogen bonding, and pi-pi stacking interaction. The highest initial specific capacitances of 746 F g(-1) (12 500 mesh) and 627 F g(-1) (500 mesh) corresponding to the mass ratios 1:200 and 1:50 (graphene oxide/aniline) are obtained, compared to PANI of 216 F g(-1) at 200 mA g(-1) by charge-discharge analysis between 0.0 and 0.4 V. The improved capacitance retention of 73% (12 500 mesh) and 64% (500 mesh) after 500 cycles is obtained for the mass ratios 1:23 and 1:19 compared to PANI of 20%. The enhanced specific capacitance and cycling life implies a synergistic effect between two components. This study is of significance for developing new doped PANI materials for supercapacitors.

Deposition of Co3O4nanoparticles onto exfoliated graphite oxide sheets

A composite of graphite oxide (GO)-supported Co3O4nanoparticles (NPs) was prepared through a facile chemical route. The lamellar GO sheets in this composite were exfoliated and decorated randomly by Co3O4 particles with an average size of 100 nm. The formation route to anchor Co3O4 NPs onto the exfoliated GO sheets was proposed as the intercalation and adsorption of cobalt ions into the layered GO sheets, followed by the nucleation and growth of Co3O4 crystals, resulting in the exfoliation of GO sheets. The nanocomposite reveals unusual catalytic effect for the decomposition of ammonium perchlorate due to the concerted effects of GO and Co3O4 NPs or their integrated properties. This methodology made the synthesis of GO-NP composites possible and may be further extended to prepare more complicated nanocomposites based on GO sheets for technological applications.

Preparation and Characterization of Mesoporous Zirconia Made by Using a Poly (methyl methacrylate) Template

Superfine powders of poly (methyl methacrylate) (PMMA) have been prepared by means of an emulsion polymerization method. These have been used as templates in the synthesis of tetragonal phase mesoporous zirconia by the sol–gel method, using zirconium oxychloride and oxalic acid as raw materials. The products have been characterized by infrared spectroscopy, X-ray diffraction analysis, transmission electron microscopy, N2adsorption-desorption isotherms, and pore size distribution. The results indicate that the average pore size was found to be 3.7 nm.

An improvement on sol-gel method for preparing ultrafine and crystallized titania powder

Abstract TiO 2 nanoparticles were prepared using a sol-gel method with inorganotitanates and polyethylene glycol (PEG). However, the way TiO 2 particles were obtained from the dry gel was not by calcining but by redissolving the dry gel which had been treated at 100°C, thereby releasing the particles. The TiO 2 powder prepared in this manner was ultra-fine (∼4 nm) and crystallized (anatase phase) merely by being exposed to 100°C while inside the gel. It was supposed that this low temperature crystallization of TiO 2 results from the special structure of the gel which formed through the linking of TiO(NO 3 ) 2  · H 2 O with PEG chains by a hydrogen bond. This preparation method also has an advantage in environmental protection.

Experimental and density functional studies on 4-(4-cyanobenzylideneamino)antipyrine

4-(4-cyanobenzylideneamino)antipyrine (CBAP) has been synthesized and characterized by elemental analysis, FT-IR, UV-VIS and X-ray single crystal diffraction techniques. Crystallographic study reveals that the compound adopts trans configuration about the Schiff base imine double bond. The substituted p-cyanophenyl ring indirectly linked to the pyrazoline ring by the C=N double bond is almost coplanar with the pyrazole ring, whereas the phenyl ring directly attached to the pyrazoline ring forms an effective dihedral angle. Density functional calculations have been carried out to optimize and to characterize the title compound by using B3LYP method at 6-31G(d) basis set. The calculated results show that the optimized geometry can well reproduce the crystal structural parameters and the theoretical vibrational frequencies show good agreement with experimental values. On the basis of theoretical vibrational analyses, the thermodynamic properties (standard heat capacities, standard entropies, and standard enthalpy changes) of the title compound at different temperatures have been calculated, revealing the correlations between , , and temperatures. The total molecular dipole moment, mean linear polarizability and mean first hyperpolarizability obtained by calculation are 3.4724 Debye, 40.154 Å3 and 4.5424 × 10−29 cm5/esu, respectively. Three absorption bands in UV-VIS are mainly derived from the contribution of bands π → π* and electrons transfer from HOMO to LUMO, LUMO + 1, LUMO + 2, respectively.

Characterization of perovskite-type LaCoO3 nanocrystals prepared by a stearic acid sol--gel process

Abstracts are not published in this journal

Experimental and theoretical studies on vibrational spectra of 4-(2-furanylmethyleneamino)antipyrine, 4-benzylideneaminoantipyrine and 4-cinnamilideneaminoantipyrine

This work deals with the IR and Raman spectroscopy of 4-(2-furanylmethyleneamino) antipyrine (FAP), 4-benzylideneaminoantipyrine (BAP) and 4-cinnamilideneaminoantipyrine (CAP) by means of experimental and quantum chemical calculations. The equilibrium geometries, harmonic frequencies, infrared intensities and Raman scattering activities were calculated by density functional B3LYP method with the 6-31G(d) basis set. The comparisons between the calculated and experimental results covering molecular structures, assignments of fundamental vibrational modes and thermodynamic properties were investigated. The optimized molecular geometries have been compared with the experimental data obtained from XRD data, which indicates that the theoretical results agree well with the corresponding experimental values. For the three compounds, comparisons and assignments of the vibrational frequencies indicate that the calculated frequencies are close to the experimental data, and the IR spectra are comparable with some slight differences, whereas the Raman spectra are different clearly and the strongest Raman scattering actives are relative tightly to the molecular conjugative moieties linked through their Schiff base imines. The thermodynamic properties (heat capacities, entropies and enthalpy changes) and their correlations with temperatures were also obtained from the harmonic frequencies of the optimized structures.

Characterization and size-dependent magnetic properties of Ba3Co2Fe24O41 nanocrystals synthesized through a sol-gel method

Ba3Co2Fe24O41 nanocrystals are synthesized through a stearic acid sol-gel method. The reaction temperatures are dramatically lower than that of the conventional ceramic method. The nanocrystalline powders obtained at 750°C were spherical in shape with grain sizes in the range 15–25 nm and become a plate-like form when the heat-treatment temperature increased. The magnetic properties of these samples are different from those of the bulk Z-type hexagonal ferrite with a lower specific saturation magnetization. This phenomenon can be attributed to the existing of a nonmagnetic layer existing on the surface of the particles. The higher value of the coercivity force is obtained when the particle sizes approximately are equal to 90 nm and assume a single-domain character. The surface composition of the nanocrystalline Co2-Z hexagonal ferrite is different from that of the bulk counterpart material with a higher content of the Ba element and Co element.

Synthesis, vibrational spectral and nonlinear optical studies of N-(4-hydroxy-phenyl)-2-hydroxybenzaldehyde-imine: A combined experimental and theoretical investigation

The study of imine-bridged organics has been the one hot spot of photo-responsive material sciences in recent years. Herein we make a study of the synthesis, characteristics and potential application of N-(4-hydroxy-phenyl)-2-hydroxy-benzaldehyde-imine (HPHBI), C13H11NO2. The studied compound was synthesized in one step by the condensation reaction of salicylaldehyde and 4-aminophenol in methanol solution, and characterized by single crystal X-ray diffraction, FT-IR and FT-Raman techniques with theoretical calculations at B3LYP/6-31G(d) level. The molecule adopts trans configuration about central CN bond with intramolecular hydrogen bonding, and the adjacent molecules form wave-shaped structure linked by strong intermolecular hydrogen bonding mechanism along b axis. The vibrational spectra have been precisely assigned with the aid of theoretical frequencies. Furthermore, the thermodynamic properties have been obtained by the theoretical vibrational analysis for HPHBI. The total linear polarizability and first-order hyperpolarizabilities calculated on the studied compound respectively present 25.378 Å3 and 1.655×10(-29) cm5/esu, which indicates the compound has relatively good nonlinear optical property.

Study on the catalytic effect of NiO nanoparticles on the thermal decomposition of TEGDN/NC propellant

The catalytic effect of NiO nanoparticles on the thermal decomposition of double-base propellant composed of nitrocellulose (NC) and triethylene glycol dinitrate (TEGDN) has been investigated by thermogravimetry-mass spectrometry (TG-MS) coupling technique. It was shown that adding 2% of NiO nanoparticles to TEGDN/NC propellant can accelerate the thermal decomposition process after around 188 degrees C TG-MS analysis indicated that NiO nanoparticles have resulted in the increase in intensity (peak area) of m/z=27, 28, and 29 MS signals, but the decrease in the intensity of m/z=18, 30, 44 and 46 (peak 2) MS signals during the thermal decompsition. The catalytic mechanism was also discussed in this paper.