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ABSTRACT: A novel hierarchical Ni-Co hydroxide assembled from two-wheeled units was successfully synthesized via a simple, hydrothermal method through the reaction of nickel salt, cobalt salt and sodium hydroxide, and with a chelating agent (EDA) to control the precipitation rate. The as-synthesized materials were characterized by x-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), Fourier transform infrared spectroscopy (FTIR), atomic absorption spectrophotometer (AAS) and thermogravimetric analysis (TG). The Ni(2+)/Co(2+) molar ratio R in the initial solution plays an important role to control the morphology of the hierarchical Ni-Co hydroxide. The influence of the EDA concentration, reaction temperature and NaOH concentration on the formation of the hierarchical Ni-Co hydroxide was also investigated. The formation mechanism of the hierarchical Ni-Co hydroxide assembled by two-wheeled units was proposed. A Ni-Co oxide with a similar structure was obtained by calcination of the as-prepared Ni-Co hydroxide.
Nanotechnology 12/2011; 23(1):015607. · 3.98 Impact Factor
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ABSTRACT: Ag nanowires within the channels of mesoporous silica have been successfully synthesized via a double solvent technique, in which n-hexane is used as a hydrophobic solvent to disperse mesoporous silica and an AgNO(3) aqueous solution is used as a hydrophilic solvent to fill mesochannels. The morphology of the obtained Ag (nanowires, nanoparticles or nanorods) can be controlled by adjusting the concentration of AgNO(3) solution and the template pore size. HRTEM images demonstrate extensive Ag nanowires with several to tens of hundreds nanometers in length are deposited along the long axis of mesochannels when the atomic AgNO(3)/Si ratio is 0.090. When the atomic AgNO(3)/Si ratio is 0.068 or 0.11, there is a combination of Ag nanoparticles and nanowires; nanoparticles are mainly formed when the atomic AgNO(3)/Si ratio is higher than 0.14. Further, the catalytic results of the oxidation of styrene show that styrene oxide and benzaldehyde are the main products of the reaction, and the morphology and diversity of Ag in Ag/mesoporous silica composites have an effect on the conversion of styrene and selectivity of styrene oxide.
Journal of Colloid and Interface Science 07/2011; 359(1):40-6. · 3.07 Impact Factor
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ABSTRACT: Ti-MCM-41 and Ti-MCM-48 are successfully prepared by one step synthesis and post-synthesis at room temperature. The samples have been characterized by X-ray diffraction, SEM, TEM, nitrogen adsorption/desorption isotherms and UV-Vis spectroscopy. The results demonstrate the existence of an ordered mesoporous structure. The Ti species are grafted into the pure silica sieve frameworks without any evidence of the formation of non-skeleton anatase. The post-synthesis Ti-MCM-41 regular nano-particles display a higher conversion and selectivity as compared to that for both the post-synthesis Ti-MCM-48 and Ti-MCM-41 with ordinary particles, in the epoxidation of cis-cyclooctene with aqueous H(2)O(2) as an oxidant. The enhanced catalytic activity may be attributed to the existence of a higher number of isolated tetracoordinated Ti active sites and regular nano-particles, which are conducive to the affinity of the reactants with active sites.
Journal of Colloid and Interface Science 10/2010; 353(2):519-23. · 3.07 Impact Factor
