Tungsten Oxide Quantum Dots Preparation by Solvent Method

Energy shortage and environmental deterioration have become the most important problems facing all countries in the world. The development of new functional materials will be an effective way to solve these problems. Because of its unique physical and chemical and electronic properties, tungsten oxide materials have good application prospects in the fields of color-changing window, photocatalysis, fuel cell, chemical sensor, environmental purification, solar energy conversion and other functions, and have become one of the hot topics in the current research of new materials.

Normally, the preparation method of tungsten oxide quantum dots is the model method, but it is difficult to remove the model in this method, which brings inconvenience for subsequent applications. Therefore, it is of great practical significance to develop an effective liquid phase method to prepare tungsten oxide quantum dot solutions with single size, uniform distribution and adjustable particle size. Some scholars have prepared tungsten oxide quantum dots by solvent method, including:

(1)The inorganic tungsten compounds as tungsten source and organic compounds as ligands are mixed in molar ratio of 1:10-1:100, heated to 30-180 for reaction time of more than 0.5 h, preferably 0.5-24 h, then cooled to room temperature, and added alkaline aqueous solution to the reaction mixture. The organic layer is extracted with the first organic solvent, and the organic layer is obtained by vacuum distillation at 30-70 ℃. Red-brown solid organic tungsten precursor;

(2)The organic tungsten precursor was preheated to 80-320oC, then mixed with the second organic solvent for more than one minute, and the optimum reaction time was 1-120 minutes. The molar ratio of the organic tungsten precursor to the second organic solvent was 1:10-1:200. After the reaction, the reaction mixture was cooled to room temperature, and the solids were separated to obtain tungsten oxide quantum dot materials.

Compared with the standard method, the liquid-phase solvent method can synthesize tungsten oxide nanoparticles from easily available inorganic tungsten compounds through organic tungsten precursors in two steps. The process is simple and easy to operate. The obtained tungsten oxide nanoparticles are uniform in size, adjustable in size, highly dispersed and have obvious quantum size effect.

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