Tungsten Oxide Nanowires Preparation by Low Temperature Hydrothermal Method

Tungsten oxide is a typical transition metal oxide with a band gap of 2.4-2.8ev, which belongs to a typical n-type semiconductor. In addition to catalysis, electrochromism, battery electrode, solar energy absorbing material and invisible material, tungsten oxide also has the properties of semiconductor functional materials such as pressure sensitive, thermal sensitive and gas sensitive.

The traditional preparation process of tungsten oxide nanowires is complex, energy consumption is large, and the experimental conditions of these methods are demanding. Some hydrothermal temperature is as high as 200 ℃, and the hydrothermal time is as long as 24 hours or even longer. In the traditional hydrothermal process, the reaction vessels used are all high-pressure reaction kettles lined with polytetrafluoroethylene. This kind of equipment consumes a lot of energy.

In order to solve the above problems, some scholars have studied a process for preparing tungsten oxide nanowires at a low temperature, and the preparation steps are as follows:

Prepare 50mL of 0.01mol/L Na₂WO₄·2H₂O aqueous solution, use (NH₄)₂SO₄ as surfactant, add 0.66g in solution; add concentrated hydrochloric acid dropwise at 0.1ml/s under magnetic stirring conditions. In the Na₂WO₄·2H₂O solution, the pH of the solution is adjusted to 5, and the dropping is stopped; the obtained mixed solution is transferred to a sealed glass bottle, and the temperature of the drying box is stabilized at 95 °C, and the glass bottle is placed in a constant temperature drying oven. The reaction was carried out for 3 hours; the precipitate obtained after the reaction was washed twice with water and ethanol, and then dried in an oven at 60 °C for 1 h. The obtained tungsten oxide was a nanowire structure having a diameter of about 10 nm and a length of 200-300nm.

Compared with the existing preparation methods of tungsten oxide nanowires, the low temperature hydrothermal method is simple in process, simple in operation, ultra-low in reaction temperature, and can greatly shorten the reaction cycle, simple in equipment requirements, just using ordinary glass containers, and lower in energy consumption and cost compared with the traditional method of PTFE lined high-pressure reactor.

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