Nano Silver / Tungsten Trioxide Photocatalyst

Tungsten trioxide (WO₃) is an important photocatalytic semiconductor material, which is widely used in the field of semiconductor heterogeneous photocatalytic technology to solve industrial wastewater and domestic wastewater pollution treatment.

With sodium tungstate as raw material, deionized water as reaction solvent, noble metal silver is loaded on the surface of catalyst. As Ag deposits on the surface of catalyst, fine metal particles can focus, thus forming an electron accumulation center, which has the best attraction to the free electrons of catalyst, increases the separation probability of photogenerated electrons and holes, and improves the photocatalytic activity of catalyst.

Nowadays, the doping of noble metal nanocrystals is involved in the methods of modifying the surface of tungsten oxide photocatalyst with noble metals to improve its photocatalytic activity. The preparation process is complex. Recently, some researchers have optimized the preparation process, simplified the process and reduced the cost without reducing the performance. The main processes are as follows:

1)Preparation of tungsten oxide flake nano-materials: 3.5G sodium tungstate was dispersed and dissolved in 20 ml deionized water for 15 minutes by ultrasound, and then filled with cation exchange resin column. The exchange rate was controlled to 25 drops per minute. The light yellow colloid of tungsten acid was prepared by full exchange. Tungsten trioxide nanosheets were prepared by hydrothermal reaction at 160 degrees Celsius for 24 hours after 18 hours of static aging. The nanosheets were washed with ethanol and deionized water three times, respectively.

2)Ultraviolet reduction: 200 ml silver nitrate solution with mass concentration of 0.4% wt was accurately prepared, and acid system with proper amount of nitric acid added to the solution at pH=1 was added. The solution was dispersed in ultrasonic generator for 10 minutes without light. The tungsten oxide nano-sheet prepared in step 1 was added to the silver nitrate solution and dispersed in the ultrasonic generator for 20 minutes, then placed in the ultraviolet lamp (wavelength 254 nm) for 15 minutes, and the final product was obtained.

3)Follow-up treatment: centrifuge the product and filter the supernatant by the method of precipitation, wash it with ethanol and deionized water for three times, transfer it to 100 ml beaker in wet state and calcine it at 250 degrees Celsius for 5 minutes on the electric heating jacket. Then a loaded nano-silver/tungsten trioxide photocatalyst with high catalytic activity can be obtained.

The preparation of tungsten trioxide nanosheets by ion exchange/hydrothermal method is based on photoreduction loaded nanosilver and calcined in wet state to improve the catalytic activity of tungsten trioxide photocatalyst. The process is low cost, simple operation and easy to industrialize.

• < Prev
• Next >