Tungsten Trioxide in Single Crystal System Preparation by Hydrothermal Method

Tungsten oxide is a new type of semiconductor material and one of the few oxide semiconductors which are easy to achieve quantum size effect. It has the characteristics of electrochromic, absorption and catalysis. It has been widely used in fuel cells, chemical sensors, optoelectronic devices and other fields.

The preparation and properties of tungsten oxide with special structure and morphology are the key technologies in the development of tungsten oxide and semiconductor materials. At present, the preparation methods of tungsten oxide are various, such as solid phase method, chemical deposition method, sol-gel method, microemulsion method, hydrothermal synthesis method, etc. different methods can be used to prepare tungsten oxide particles with different structures, such as tetragonal, six square crystal, monoclinic, orthorhombic system, etc.

In the application of photocatalysis, the tungsten oxide materials prepared by the existing tungsten oxide technology are applied to textile printing and dyeing industry and environmental protection, which show some shortcomings such as weak adsorptivity and poor treatment effect of dye wastewater. In order to improve the photocatalytic performance of tungsten oxide, hydrothermal method has been used to prepare single crystal tungsten trioxide. The main processes include:

(1)Preparing precursor solution: adding tungstate into water, the molar ratio of water to tungstate is 241 to 483;

(2)Adjusting the pH value: adding acid and stirring to the forward body solution, adjusting the pH value of the solution from 1 to 2;

(3)The above solution was kept for 0.5 to 3 days.

(4)The static solution was moved into the PTFE hydrothermal kettle and aged for 6 hours to 8 days at 40 ~180 ~℃.

(5)The sample obtained in step (4) was centrifuged and washed three times with water, then dried in a constant temperature drying box at 100 ℃ for 24 hours to prepare rod-like single crystal WO₃ material.

A single crystal tungsten trioxide material with high specific surface area and strong adsorbability for dyes was obtained by a simple hydrothermal method. The key is to adjust the ratio of raw materials, aging time and aging temperature to control the size, crystal surface structure and adsorption properties of WO₃ single crystal. The smaller the single crystal particle is, the larger the specific surface area is, the stronger the dye adsorption performance is, and the dye wastewater treatment effect is good. According to the test, the prepared single crystal tungsten oxide material has strong adsorbability to rhodamine B, methylene blue and other dyes, and has a good effect on the treatment of dye wastewater.

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