Tungsten Trioxide Nanosheets Preparation by Thermal Oxidation

Tungsten trioxide (WO₃) is an n-type semiconductor oxide with wide band gap. Ordered nanostructured WO₃or hydrated WO₃ has the characteristics of quantum effect and surface effect unique to nanomaterials. It has wide application prospects in gas sensing, photocatalysis, energy storage devices and other fields.

The properties and applications of semiconductor materials are closely related to their microstructures and morphologies. Among them, two-dimensional nano WO₃ or hydrated WO₃with high specific surface area have attracted more and more attention due to their unique photoelectric properties.

How to reduce its thickness or obtain single-layer nanosheets is of great significance. Some scholars have prepared tungsten trioxide nanosheets by thermal oxidation method. The process includes the following steps:

(a)The first tungstic acid base was obtained by mixing wolframic acid with auxiliary stripping agent and ultrasonic treatment.

(b)The first tungstic acid base material is mixed with the main stripping agent and heated to obtain the second tungstic acid base material.

(c)Monolayer hydrated tungsten trioxide nanosheets were prepared by mixing and filtering the base material of tungstic acid with nitric acid.

The specific operation is as follows: mixing 0.5g yellow tungstic acid (about 2mmol) with 0.5mL methanol (12mmol) and ultrasonic treatment at 100W for 5min, adding 10mL tetradecylamine (38mmol), reacting at 120 ℃ for 24h, then adding sufficient acetone to the obtained mixture to form precipitation and filtration; mixing the obtained white precipitation with 50mL nitric acid solution with 4mol/L concentration, filtering after 36 hours of magnetic stirring, and filtering out. Monolayer tungsten trioxide nanosheets were prepared by yellow precipitation drying. The preparation method is simple, easy to operate and low in cost, so it is convenient for large-scale production.

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