Sol-Gel Hydrothermal Method for The Preparation of Bismuth Tungstate Photocatalyst

Bismuth tungstate (Bi₂WO₆) photocatalyst is considered to be a potential excellent visible light photocatalyst because of its unique electronic structure, excellent visible light absorbability and high organic degradation ability. At present, the preparation methods of bismuth tungstate are mainly concentrated in coprecipitation and hydrothermal methods.

The sol-gel hydrothermal method is an upgrade for the preparation of bismuth tungstate photocatalyst by hydrothermal method. This method can be used for doping in the sol-gel process and hydrothermal reaction, can overcome the existing preparation method of bismuth tungstate crystal agglomeration, difficult doping defects, prepared with small particle size, low agglomerated and complete crystal form, nano bismuth tungstate doped photocatalyst, the this process is as follows:

(1)With ammonium tungstate, bismuth nitrate, EDTA and deionized water as raw materials, ammonium tungstate and bismuth nitrate and deionized water were mixed into aqueous solution respectively. Then EDTA solution was added into ammonium tungstate solution and bismuth nitrate solution to form transparent solution under stirring conditions.

(2)Step (1) of the transparent solution molar of n (H₄₀N₁₀O₄₁W₁₂): n (Bi (NO₃) ₃) =1:24 mixed, in this process can also add other elements to composite, such as indium, silver, cobalt etc.. Then the wet gel was kept in the water bath at 60~80 ℃ for 12~24 hours, and the wet gel was dried at 110 degrees C. Then, the obtained transparent mixture solution was kept in a water bath at 60-80 ℃. for 12-24 hours to obtain a wet gel, and the wet gel was dried at 110 ℃ to obtain a dry gel.

(3)The xerogels obtained from step 2 were moved to a hydrotherm kettle, and the pH value of the reaction solution was adjusted to 2~11 with acid or alkali. Then, after 6~36 hours at 180~240 ℃, the bismuth tungstate photocatalyst with high catalytic activity was obtained after cold filtration, filtration, washing and drying.

The bismuth tungstate photocatalyst obtained by sol-gel hydrothermal method has good crystalline properties, and the morphology is folded sphere. It has a large specific surface area and good photocatalytic activity. It overcomes the shortcoming that the grains are easily agglomerated and difficult to be doped in the preparation of bismuth tungstate, and prepare nanometer bismuth tungstate photocatalyst with small particle size, low agglomeration degree, complete crystal structure and easy doping.

• < Prev
• Next >