Advanced Materials Research Vol. 643

Abstract: Synthesis of titanium dioxide sol was prepared by sol-gel method, using tetrabutyl titanate as source, ethanol as solvent, acetic acid as complexing agent. A transparent sol aging in air 30min, titanium dioxide films were prepared by using spin coating method. Congo red degradation was investigated by TiO₂ photocatalysis. Study the efficiency of decolorization was influenced by the coating times, heat-treated time, the initial concentration of congo red and solution pH.

Abstract: Titanium tetrachloride with inorganic salts as raw materials in the experiment, TiO₂ is prepared by the hydrolyzation method in (NH₄)₂SO₄-modified TiCl₄ solution, the maximal photocatalytic activity is observed at the mole ratio of TiCl₄: (NH₄)₂SO₄=1:2, the water-bath temperature of 90°C. Bromophenol blue solution is degraded by the nanometer TiO₂. The photocatalytic degradation efficiency is influenced by the nanometer TiO₂ amount, irradiation time, the UV irradiation intensity and solution temperature. The short degradation time shows that the nanometer TiO₂ can be used as an easy and efficient method to degrade bromophenol blue solution.

Abstract: Single crystalline CdS dendrites were successfully synthesized in high yield by a simple and facile hydrothermal method. The allyl thiourea and CdCl2•5H2O were used as raw materials for the synthesis of dendritic CdS nanostructures for the first time. The as-prepared products were characterized by X-ray powder diffraction, scanning electron microscopy, transmission electron microscope and selected area electron diffraction. The results demonstrate that the petal in an individual dendritic CdS nanoarchitecture is single crystalline and prefers growth along the [101] direction. The reaction parameters affected the CdS morphology were investigated systematically. It is found that the morphology of the samples are strongly dependent on the cadmium source, sulfide source, the reaction time and the solvent, the temperature has no effect on the morphology of the products. The possible mechanism was proposed for the formation of dendritic CdS nanostructures

Abstract: In order to avoid their agglomeration and incompatibility with polymer matrix, hydrophobic magnesium hydroxide nanoparticles were obtained by means of grafting polystyrene (PS) onto the surface of nanoparticles after oleic acid (OA) modification. Firstly, the functional double bonds were conducted on the surface of blank magnesium hydroxide nanoparticles by OA modification, and then, PS was grafted on the surface of OA-modified magnesium hydroxide. The microstructure of resultant sample was characterized by TEM, TGA and FTIR. In the meantime, the compatibility with some organic solutions was determined by dispersibility evaluation. The results show that the organic macromolecule PS could be successfully grafted on the surface of OA-modified magnesium hydroxide nanoparticles, and the dispersibility and the compatibility of nanoparticles greatly improved in organic phase.

Abstract: We report on a simple method for the fabrication of metalized tips by depositing gas-phase synthesized silver nanoparticles onto atomic force microscope (AFM) tips. The method enables fabricating tips suitable for AFM based tip-enhanced Raman spectroscopy (TERS) with high yield. The performance of the fabricated silver nanoparticle decorated tips is examined by detecting low concentration BPE molecules using a transmission mode TERS setup. An 30-fold enhancement of the Raman signal is shown. The net TERS enhancement factor is calculated to be about 1000.

Abstract: Nanoscale thermodynamics and kinetics were explored via the manipulation of Pb/PbO core-shell nanoparticles with a focused electron beam which served as a nanometer heating probe. In the electron transmission microscope (TEM), when an electron beam of moderate intensity was used to irradiate the nanoparticles, the amorphous particles gradually crystallized and showed distinct boundaries between lead cores and oxide shells. In such a way, the oxide shell could be easily measured to be 0.5-2 nanometers. With a high intensity electron beam, melting of the lead cores could be observed, indicating a sufficient local temperature increasing induced by the concentrated heat generated by inelastic electron collisions. The fluidic metal core erupted out through the cracked shells accompanied with the vanish of the boundaries between the cores and shells. Manipulations on nanoparticle decorated carbon wires proved that the lead oxide shells could sustain the irradiation of intense electron beam.