Method for preparing visible light catalyst of Nano crystal BiVO4 in high activity through ultrasound chemistry

[0027] Example 1

[0028] BiVO 4 Using Bi(NO 3 ) 3 ·5H 2 O and NH 4 VO 3 (Analytical pure) is synthesized as raw material, according to stoichiometric ratio, weighs 0.97g Bi(NO 3 ) 3 ·5H 2 O (analytical grade) was dissolved in 70 mL of water, and then 0.234 g of NH 4 VO 3 (analytical pure), stirring to form a yellow suspension precursor. Then immerse the ultrasonic probe in it for ultrasonic treatment. After comparative experiments, the diameter of the titanium alloy working probe is selected to be 0.6cm, the power of the ultrasonic wave is 500W, and the reaction time is 1h. After the reaction, the obtained yellow precipitate was filtered, washed three times with deionized water and absolute ethanol, and then dried at 80°C. like figure 1 , by XRD component analysis and Debye Scherer formula calculation, the monoclinic phase BiVO of about 50nm was obtained 4 Nanocrystalline. figure 2 Among them, A and B are typical scanning electron micrographs of different magnifications of samples prepared by the ultrasonic preparation method provided by the invention respectively. As can be seen from the figure, BiVO with a particle diameter of about 300nm 4 The particles are aggregated by nanocrystals with a size of about 50nm.

[0029] By measuring the UV/visible diffuse reflectance spectrum of the product, the BiVO prepared by the present invention 4 The photocatalyst is photoresponsive from the ultraviolet region all the way to the visible region with an estimated bandgap of 2.45eV.

[0030] In order to study the photocatalytic performance of the prepared samples, an experiment was designed to degrade methyl orange dye under visible light. Utilizing the photocatalytic degradation and decolorization properties of methyl orange, the absorbance of the solution at 464nm was measured by ultraviolet/visible absorption spectrum to observe the change of the chromaticity of the solution, and then obtain the decolorization rate. For comparison, the same amount (0.06 mmol) of BiVO prepared by sonochemical method 4 Powder, BiVO prepared by solid state reaction 4 Add powder and P25 powder to 60mL of methyl orange solution with a concentration of 40mg/L, and stir for 30 minutes in the dark to achieve adsorption equilibrium, and then irradiate under a 500W high-pressure mercury lamp filtered by a filter of λ>400nm . After 30 minutes of visible light photocatalytic degradation, under the naked eye, the BiVO prepared by sonochemical method 4 The degradation effect of the powder is obvious, and the solution is obviously faded, while the degradation effect of the other two photocatalysts is not obvious. image 3 The time-dependent change of the absorbance of the methyl orange solution in the ultrasonic sample suspension is given, and it can be seen that it is basically degraded into a colorless solution in only 30 minutes. As a comparison, Figure 4The amounts of the same substances are given in BiVO prepared by sonochemical reaction, solid-state reaction 4 The degradation of powder and P25 under the same conditions, in the figure C 0 is the initial concentration of the solution, and C is the solution concentration at time t. Obtained by spectrophotometric measurement and calculation: BiVO prepared by sonochemical method 4 The visible light degradation rate of the powder is 90%, and the degradation efficiency is the same as that of nano-TiO 2 (P25) ten times (P25 efficiency is 6%). However, BiVO with the same crystal form and the same components prepared by the solid-state reaction method 4 The photocatalytic degradation efficiency is only 8%, demonstrating its high visible-light photocatalytic activity.

[0031] Example 2

[0032] BiVO 4 Use BiCl 3 and NH 4 VO 3 Synthesize as raw material, according to stoichiometric ratio, weigh 0.631g BiCl 3 (analytical pure) was dissolved in 70mL water, then added 0.2g polyethylene glycol (PEG20000), stirred for 30 minutes, then added 0.234g NH 4 VO 3 (analytical pure), stirring to form a yellow suspension precursor. Then immerse the ultrasonic probe in it for ultrasonic treatment, the ultrasonic power is 600W, and the reaction time is 1h. After the reaction, the obtained yellow precipitate was filtered, washed three times with deionized water and absolute ethanol, and then dried at 80°C. The product was determined to be monoclinic phase BiVO by XRD component analysis 4 , the particle size observed by an electron microscope is about 200nm, and the visible light degradation experiment result of wavelength λ>400nm is slightly lower than that of Example 1, and the degradation rate is 70%.

[0033] Example 3

[0034] BiVO 4 Use BiCl 3 and NH 4 VO 3 Synthesize as raw material, according to stoichiometric ratio, weigh 0.631g BiCl 3 (analytical pure) was dissolved in 70mL of water, then added 0.2g cetyltrimethylammonium bromide (CTAB), stirred for 30 minutes, then added 0.234g NH 4 VO 3 (analytical pure), stirring to form a yellow suspension precursor. Then immerse the ultrasonic probe in it for ultrasonic treatment, the ultrasonic power is 600W, and the reaction time is 1h. After the reaction, the obtained yellow precipitate was filtered, washed three times with deionized water and absolute ethanol, and then dried at 60°C. XRD component analysis showed that the product was monoclinic phase BiVO 4 , the particle size of the product is about 500nm according to scanning electron microscope analysis. The visible light degradation experiment of methyl orange with wavelength λ>400nm shows that the visible light photocatalytic performance of the product prepared by using CTAB as surfactant is not ideal.