Preparation Method of Tungsten-Based Tungsten Trioxide Nanofilm

In recent years, research on tungsten trioxide (WO3) nanofilm has attracted more and more attention. WO3 is an n-type semiconductor material with a narrow band gap (2.4-2.8eV), is capable of responding to visible light, and has similar characteristics to TiO2 photocatalyst, namely stable, non-toxic, photo-resistant, low-cost and low-priced. The potential of the belt is high and the photo-generated holes are highly oxidizing.

The tungsten trioxide film has photoelectrocatalytic performance and sensing performance, and can be used for photocatalytic degradation of organic matter, photocatalytic decomposition of water to produce hydrogen, and pH, CH4, NO2 sensors, etc. However, the microstructure of the tungsten trioxide film determines the photocatalytic performance, sensing performance and service life of the tungsten trioxide film.

The preparation of the existing tungsten trioxide nanofilm is mainly done by hydrothermal chemical method. However, in the existing hydrothermal chemical preparation method, since the substrate is made of conductive glass, the conductive glass and the WO3 are between different elemental substances. The combination is unnatural, and the mutual bonding force is poor, especially when subjected to mechanical external force, or when the ambient temperature changes, due to the different material expansion coefficients, the internal stress will change, thus making WO3 and conductive glass Cracking or fracture occurs between the substrates. The unnaturally bonded film between the different elements has a slow charge transfer and charge recombination, which will seriously affect the photoelectrocatalytic performance, electrochemical performance and sensing performance of the material, and affect its application.

Regarding this, some researchers have developed a tungsten-based tungsten trioxide nanofilm material which has the same natural elements as the substrate, and has high catalytic performance or sensing performance. The tungsten trioxide nanofilm preparation method is as follows:

The polished and cleaned tungsten flakes are dried, placed in a muffle furnace, and the temperature is controlled at 450-650 ° C for 30 min, and a layer of WO3 fine particles is formed on the surface of the metal tungsten as a seed crystal for subsequent crystal growth; WO3 will be attached The tungsten sheet of the seed crystal is immersed in a hydrothermal reaction system, and the hydrothermal reaction system contains polyethylene glycol having a volume fraction of 5 to 15% and a molecular weight of 200-400 as a crystal growth directing agent and tungsten having a concentration of 0.01-0.03 mol/L. The sodium solution is used as a material for crystal growth. The inner wall of the reaction vessel is a polytetrafluoroethylene material. The pH of the reaction solution is adjusted to 1.0 to 2.0 with hydrochloric acid, the reaction temperature is controlled at 160 to 200 ° C, and the reaction time is 2-8 h. Oriented growth of tungsten trioxide on the surface of the substrate tungsten; the tungsten-based tungsten trioxide reaction product is taken out, repeatedly immersed in distilled water to remove the residue on the surface of the product, then dried, placed in a muffle furnace, and calcined at 450-650 ° C for 180 min. That is, the preparation of the tungsten-based tungsten trioxide nano-film material is completed.

Compared with the existing conductive glass-based tungsten trioxide thin film, the tungsten-based tungsten trioxide nanofilm material has the advantages of strong bonding and stable structure between the substrate and the tungsten oxide, and good photoelectric catalytic performance, electron transport performance and sensing performance. At the same time, it has good mechanical stability and service life, and can be widely used in photocatalytic degradation of organic matter, photocatalytic degradation of organic matter and decomposition of hydrogen production, photocatalytic COD sensors, pH sensors and gas sensors.

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