Defective Tungsten Trioxide Preparation

In the research of traditional catalysts, titanium dioxide (titanium dioxide) is widely used to treat various environmental pollution problems by its photocatalytic reaction. However, titanium dioxide can only be stimulated by ultraviolet light, and ultraviolet light only accounts for about 5% of the energy in sunlight. Therefore, there is a problem of insufficient utilization of solar energy. Therefore, researchers are looking for other new photocatalysts, including trioxide. Tungsten oxide (WO₃), however, can absorb UV light with wavelength less than 460nm. The utilization of other visible and infrared energy is still low.

To this end, some scholars have proposed a method for preparing defective tungsten trioxide for photocatalytic aerobic coupling. The main process includes the following steps:

(1)The tungsten source is connected to the evaporation electrode of the vacuum hot evaporation coating machine, and the substrate is placed at a distance of 2-100 mm from the tungsten source.

(2)Open the mechanical pump and vacuum the vacuum coating chamber for 20 minutes.

(3)Introduce oxygen and inert gas into the vacuum coating chamber, and keep it for 20 minutes after the pressure in the chamber is stable.

(4)Continuously inject oxygen and inert gas into the vacuum coating chamber, turn on the heat evaporation power supply, heat the tungsten boat to 1200 ℃ or above, and then keep it for 20 minutes, so that the surface of the boat is oxidized and sublimated into a vapor tungsten oxide layer, and then solid tungsten oxide is grown on the substrate.

(5)Close the oxygen valve, interrupt the oxygen supply, and conduct high temperature anoxic treatment for 10 minutes at 1200 ℃ or above.

(6)Turning off the power supply of thermal evaporation and cooling the substrate to room temperature in the vacuum coating chamber resulted in the growth of anoxic tungsten oxide photocatalyst on the substrate.

The above process uses vacuum hot evaporation coating machine to complete the steps of preparing tungsten oxide and high temperature anoxic treatment. The whole preparation process is in place in one step without opening the vacuum coating chamber or using other equipment. The preparation efficiency is high and the preparation conditions are easy to adjust. It is beneficial to improve the controllability of operation and the stability of catalyst products. By limiting the distance between the substrate and the tungsten boat, the pressure in the chamber, the flow rate of oxygen and inert gas, heating temperature and treatment time, the final prepared tungsten oxide photocatalyst has wide spectral response, high crystallinity and stable structure. Compared with ordinary tungsten trioxide WO₃, anoxic tungsten oxide has obvious energy absorption response in infrared band, prominent broad spectral response characteristics and good photocatalytic performance.

• < Prev
• Next >