[show abstract][hide abstract] ABSTRACT: This study reports the fabrication of a novel hierarchically structured nanocatalyst system possessing a well-defined nickel silicate (NS) protected Fe(3)O(4) core and a layer of uniform Ag nanoparticles on the NS shell by using a multi-step approach. The multifunctional microparticles show high performance in the reduction of 4-nitrophenol and the rate of the catalytic reaction can be controlled by changing the concentration of nanocatalysts. In particular, there was no visible decrease in the catalytic activity of the reused catalysts even after being recycled five times. Thus the hierarchically structured Fe(3)O(4)@NS particles are very suitable as a catalyst support for catalyst separation and redispersion.
[show abstract][hide abstract] ABSTRACT: In this paper, nanoporous strontium titanate (SrTiO3) with controllable morphologies was prepared by a simple and rapid ultrasound irradiation method. SrTiO3 particles were synthesized by the hydrolysis of strontium alkoxide in an alcohol/water solution and the morphology was controlled by adjusting the reaction pH value. A possible formation mechanism for the nanoporous SrTiO3 is proposed and the relevant influence of parameters is discussed. The chemical composition, porosity, microstructure and surface morphology of products were characterized by x-ray diffraction (XRD), the nitrogen adsorption–desorption method, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Nanoporous SrTiO3 can be used as the precursor for an electrorheological fluid and experimental results indicated that the as-prepared SrTiO3 electrorheological fluid (ERF) exhibited high shear stress and showed shear thinning behavior.
Smart Materials and Structures 05/2011; 20(6):065002. · 2.02 Impact Factor
[show abstract][hide abstract] ABSTRACT: A novel sonochemical method is described for the preparation of Fe3O4–TiO2 photocatalysts in which nanocrystalline titanium dioxide particles are directly coated onto a magnetic core. The Fe3O4 nanoparticles were partially embedded in TiO2 agglomerates. TiO2 nanocrystallites were obtained by hydrolysis and condensation of titanium tetraisopropyl in the presence of ethanol and water under high-intensity ultrasound irradiation. This method is attractive since it eliminated the high-temperature heat treatment required in the conventional sol–gel method, which is important in transforming amorphous titanium dioxide into a photoactive crystalline phase. In comparison to other methods, the developed method is simple, mild, green and efficient. The magnetization hysteresis loop for Fe3O4–TiO2 nanocomposites indicates that the hybrid catalyst shows superparamagnetic characteristics at room temperature. Photocatalytic activity studies confirmed that the as-prepared nanocomposites have high photocatalytic ability toward the photodegradation of RhB solution. Furthermore, the photodecomposition rate decreases only slightly after six cycles of the photocatalysis experiment. Thus, these Fe3O4–TiO2 nanocomposites can be served as an effective and conveniently recyclable photocatalyst.
International Journal of Smart and Nano Materials. 11/2010; 1(4):278-287.
[show abstract][hide abstract] ABSTRACT: a b s t r a c t A Fe 3 O 4 /Ag composite, with high efficiency in the degradation of rhodamine B was synthesized through a simple sonochemical method. These composites were obtained from sonication of Ag(NH 3) 2 + and (3-aminopropyl)triethoxysilane (APTES)-coated Fe 3 O 4 nanoparticles solution at room temperature in ambient air for 1 h. A formation mechanism was proposed and discussed. This sonochemical method is attractive since it eliminated the use of any reductants, which is necessary to transform the Ag + to the Ag 0 . In comparison to high temperature or high pressure experimental processes, this method is mild, inexpensive, green and efficient. The M–H hysteresis loop of these Fe 3 O 4 /Ag composite microspheres indicates that the composite spheres exhibit superparamagnetic characteristics at room temperature. Furthermore, these composites can be recycled six times by magnetic separation without major loss of activity. Thus, these Fe 3 O 4 /Ag composites can be served as effective and convenient recyclable catalysts for practical application.
Journal of Alloys and Compounds 01/2010; 508:400-405. · 2.39 Impact Factor