Cadmium Selenide-Bismuth Tungstate Composite Photocatalyst

Cadmium selenide nanocrystals are the most widely studied and promising class of II-VI semiconductor nanocrystals. They have attracted worldwide attention due to their important non-linear optical properties, luminescent properties and other physical and chemical properties.

Cadmium selenide is a direct bandgap semiconductor material with a band gap of 1.7eV. It has two crystal structures, cubic sphalerite and hexagonal wurtzite. The cubic phase structure is metastable and can only exist at lower temperatures, but can be transformed into hexagonal phase structure at high temperatures. There are cubic and hexagonal crystal phases in cadmium selenide at room temperature.

However, cadmium selenide is easy to be photoetched and has poor photocatalytic stability. In the application of photocatalysis, it needs to be combined with other semiconductor photocatalysts. However, the light absorption threshold of ordinary titanium dioxide is limited to ultraviolet light, and the solar utilization rate is low, which greatly limits their performance.

In the process of research, some scholars choose to replace titanium dioxide with bismuth tungstate. The preparation of cadmium selenide-bismuth tungstate composite photocatalyst provides the following technical scheme:

1.Compound sodium tungstate solution with bismuth nitrate solution to obtain precursor solution. Then, the precursor solution is placed in a sealed state at 160 ℃ for 20 hours. After natural cooling to room temperature, bismuth tungstate powder is obtained by centrifugation, washing and drying.

2.Cadmium selenide quantum dots were prepared by dissolving cadmium chloride hydrate and 3-mercaptopropionic acid (stabilizer) in deionized water at a molar ratio of 1:1.55 and adjusting the solution pH to 7-8 with sodium hydroxide.

3.Cadmium selenide quantum dots and bismuth tungstate were dissolved in deionized water, stirred for 10 minutes, refluxed for 24 hours at 100 ℃, and centrifugally dried to obtain CdSe-Bismuth Tungstate composite photocatalyst.

Compared with CdSe-Ti₂ composite photocatalyst, CdSe-Bismuth Tungstate composite photocatalyst has good catalytic activity and high stability.

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