Preparing Tungsten Trioxide Nanomaterial with Liquid-Phase Method

Tungsten trioxide is an indirect band gap n-type semiconductor metal oxide, which has broad application prospects in electrochromism, semiconductor, gas sensors and photocatalysis. Nano-sized tungsten trioxide has excellent properties. It has strong absorption for electromagnetic waves, which makes it to be solar energy absorbing material and military stealth material. The huge specific surface area and surface effect make it a kind of excellent catalyst. In addition, as a transition metal compound, it also possesses semiconductor properties and is a sensing material with great potential.

There are many preparation methods for tungsten trioxide nanomaterials. Some scholars have proposed a liquid-phase method, which needs to be completed as follows:

1) Firstly place the metal tungsten sheet in deionized water or distilled water under stirring. Then, use a laser (with a wavelength of 532 nm or 1064 nm, a pulse width of 5 to 15 ns, a repetition frequency of 1 to 20 Hz, and a single pulse energy of 50 to 120 mJ) Laser to irradiate the tungsten sheet for at least 10 minutes to obtain a tungstic acid colloidal solution. Followed by aging treatment of the tungstic acid colloidal solution for at least 24 h, or adding an acid to the tungstic acid colloidal solution to adjust the pH to ‐0.6 to 3.0 to obtain a yellow precipitate.

2) Firstly centrifuge and wash the yellow precipitate to obtain tungstic acid. Then anneal the tungstic acid at 480 to 520 ° C for at least 1 h to obtain a tungsten trioxide nanomaterial (with a thickness of 10 ~ 30 nm, a sheet width of 10 nm ~ 1.4 μm, and having a sheet length of 10 nm ~ 2.8 μm.).

Wherein, the purity of the metal tungsten sheet is ≥99.9%; the acid is added to the tungstic acid colloid solution to adjust the pH value to‐0.6 ~ 1.0, or the pH of the metal tungsten sheet is first stirred. ——0.6～1.0 in the acid solution; the acid is sulfuric acid, or hydrochloric acid, or nitric acid; the laser has a pulse width of 10 ns, a repetition frequency of 10 Hz, and a single pulse energy of 80 mJ; the spot diameter of the laser The laser having an emission wavelength of 532 nm or 1064 nm is an Nd:YAG solid laser; the centrifugal and washing treatment is 3 to 5 times; and the centrifugal speed is 8000 to 12000 r. /min; The washing treatment is washed 3 to 5 times with water and ethanol.

Using the liquid-phase method to produce tungsten trioxide nanomaterial has many advantages. The tungsten acid colloid solution is obtained by laser irradiation of the tungsten sheet in the liquid medium, and the yellow precipitate is obtained by aging the tungstic acid colloid solution or adjusting the pH of the tungstic colloidal solution, or directly adjusting the pH of the liquid medium. After the value is irradiated by the laser to the tungsten flakes to obtain a yellow precipitate, and then the yellow precipitate is annealed, the neutral or acidic tungstic colloidal solution is easily obtained, and trace impurity cations are avoided. The adverse effects on the tungstic colloidal solution are also achieved by aging the tungstic acid colloidal solution or adjusting the pH value, or directly adjusting the pH of the liquid medium to achieve a large range of product morphology and size. The purpose of effective regulation is to make the prepared products have broad application prospects.

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