The Sonochemical Preparation of Other Oxides

Brij-35 [polyoxyethylene (23) lauryl ether] stabilized palladium nanoparticles, obtained on attempted sonochemical reduction of PdCl2, by sodium sulfite in water 

Two reports have been published on the sonochemical preparation of nanosized ceria, Ce02 [133, 134]. Zhu and coworkers [133] synthesized nanocrystalline ceria (Ce02) particles via sonochemical and microwave assisted heating routes from aqueous solutions containing (NH4)2Ce(N03)6, hexamethylenetetramine and poly (ethylene glycol) (PEG Mw = 19,000). Analysis of the results showed that the products had a uniform shape, narrow size distribution, and displayed conspicuous quantum size effects. 

A composite material made of zinc oxide and polyvinyl alcohol was prepared by a sonochemical method [135]. Annealing of the composite under air removed the polymer, leaving porous spheres of ZnO. This change was accompanied by a change in the surface area from 2 to 34 m g k The porous ZnO particles were used as the electrode material for dye-sensitized solar cells (DSSCs). They were tested by forming a film of the doped porous ZnO on a conductive glass support. The performance of the solar cell is reported. 

A very unusual and previously unknown oxide of copper, the paramelaconite, CU4O3, was synthesized sonochemically in a polyaniline matrix [136]. An aqueous solution of copper (II) acetate and aniline (1 10 molar ratio) is irradiated by ultrasound to produce nanophased CU4O3 embedded in a polyaniline matrix. The as-prepared Cu403-polyaniline is characterized by X-ray diffraction (XRD), and other methods. The mechanism for the fabrication of Cu403-polyaniline is proposed and discussed. This method is general and works also for the production of nanocrystalline Fe304 and CU2O embedded in polyaniline. This technique is also an easy route for the production of other metal oxides embedded in polyaniline. 

Amorphous tungsten oxide has been prepared by ultrasound irradiation of a solution of tungsten hexacarbonyl W(CO)6 in diphenylmethane (DPhM) in the presence of an Ar (80%) and O2 (20%) gaseous mixture at 90 °C [137]. Heating this amorphous powder at 550 °C under Ar yields snowflake-like dendritic particles consisting of a mixture of monodinic and orthorhombic WO2 crystals. Annealing 

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