One-atmosphere aqueous-solution synthesis of trimolybdate nanomaterials and the feasibility for mass production.

Mass production of low-cost functional nanomaterials is an important issue for the development of nanoscience and nanotechnology. With rich structural, physical and chemical properties, polyoxometalates are important functional materials for both industrial applications and fundamental research. We presented a family of alkali trimolybdate nanowires and nanorods that were synthesized by a one-atmosphere aqueous solution method from a mixture of two solutions, one consisting of (NH4)6Mo7O24 x 4H2O and the other of Li+, Na+, K+ and Rb+ ions, respectively. This family showed clear similarities in their Raman and infrared spectra. By systematic characterizations, we have figured out a universal formula theta(m)(NH4)(2-m)Mo3O10 x nH2O (theta = Li, Na, K, Rb; m = 1,2) for this family of hydrate nanomaterials. Among them, two new phases, namely Li2Mo3O10 x H2O and Rb2Mo3O10 x 3 x 4H2O were recognized. The method was also applied to synthesizing Ag-doped trimolybdate nanowires, and the feasibility for mass production of these nanomaterials with a continuous synthesis experiment was also clear demonstrated. The results of this work offered interesting experimental data for theoretical analysis of the unique growth mechanism.

Fabrication of nanochannels with water-dissolvable nanowires.

We report here a template method for the fabrication of nanochannels with water-dissolvable NaNH(4)Mo(3)O(10).H(2)O nanowires as the sacrificial material. By using these nanowires, which have diameters ranging from 20 to 150 nm and lengths up to a hundred microns, we have demonstrated that it is possible to obtain nanochannels with the desired shape of cross section, and desired types of channel material, such as metals and oxides. This technique shows a good potential for the development of various microfluidic and nanofluidic devices.

Room temperature synthesis of K2Mo3O10x3H2O nanowires in minutes.

Polyoxometalates have been widely used in the fields of catalysis, analytical chemistry, biochemistry, medicine and synthesis of novel organic-inorganic materials. It is difficult to synthesize pure polymolybdate products from a solution because several kinds of molybdenum-based anions may coexist. As a result, varied acidification methods are commonly used for solution synthesis of polymolybdates. In this paper we report an approach for the synthesis of [001]-oriented K(2)Mo(3)O(10)x3H(2)O nanowires from an aqueous solution of (NH(4))(6)Mo(7)O(24)x4H(2)O and KCl at low temperatures. The reaction occurs even at temperatures as low as 0 degrees C, and at 30-90 degrees C the whole procedure needs only a few minutes. Without any additional acidification treatments, the pH value of the solution is maintained in a narrow range of +/- 0.1 between 4.9 and 5.5 during the whole synthesis procedure. The starting pH depends on the reaction temperature. Crystalline structure and purity of the final products have been characterized with x-ray diffraction, electron diffraction and dehydration measurements. This simple and rapid method provides a unique case for studying the growth mechanism of polymolybdate nanostructures, and has a promising potential in the mass production of low-cost, pure-phase polymolybdates for a variety of applications.