CN115646513A - Preparation method and application of BiOBr/BiOI/SDBS composite material with microspherical appearance - Google Patents

Abstract

The invention discloses a preparation method and application of a BiOBr/BiOI/SDBS composite material with a microspherical shape, using Bi(NO ₃ )·5H ₂ O as a Bi source, SDBS as a surfactant, and absolute ethanol as a solvent , to prepare solution A; take NaBr as the Br source, KI as the I source, and absolute ethanol as the solvent to prepare solution B; after the two solutions of A and B are sonicated respectively, solution B is added dropwise to solution A and Stirring is carried out; after the stirring is completed, the mixed solution is put into a closed reaction kettle, and a solvothermal reaction is carried out in an oven, and finally a yellow powder is obtained as a BiOBr/BiOI/SDBS photocatalytic material. In the present invention, by controlling the atomic ratio of Br and I, a BiOBr/BiOI/SDBS composite material capable of efficiently degrading RHB can be prepared. The appearance of the BiOBr/BiOI/SDBS composite material is a microsphere shape formed by gathering thinner nanosheets, The particle size of the microspheres is 1-1.5μm; the microspheres formed by the aggregation of nanosheets have larger gaps, which is conducive to the refraction of light, thereby absorbing more visible light, and has higher photocatalysis for degrading organic dyes under visible light efficiency.

Description

A preparation method of BiOBr/BiOI/SDBS composite material with microspherical morphology law and application

technical field

The invention belongs to the technical field of semiconductor material photocatalysis, relates to BiOBr and BiOI materials, in particular to a preparation method and application of a BiOBr/BiOI/SDBS composite material with a microspherical shape.

Background technique

With the progress of society and the development of science and technology, problems such as environmental pollution and energy shortage have become more and more severe. At present, environmental problems mainly include water pollution, air pollution and soil pollution. Among them, the problem of water pollution is particularly serious, mainly caused by the massive discharge of industrial wastewater. Industrial wastewater contains a large amount of organic pollutants such as dyes, which has certain toxicity and seriously affects people's domestic water and health. These pollutants have stable chemical properties, complex structures, and are difficult to completely degrade. Moreover, their degradation costs are high and time-consuming, making it difficult to meet current requirements. Photocatalysis is the use of semiconductor materials to degrade organic matter through an oxidation reaction under light conditions. This method is environmentally friendly, highly efficient in degrading organic matter in water pollution, and has good application value.

So far, researchers have demonstrated that there are a variety of semiconductors capable of generating electrical and chemical energy under visible light, such as gC ₃ N ₄ , MoS ₂ , BiOBr, TiO ₂ and BiOI, among others. However, when these materials are used alone as photocatalysts, there are some disadvantages, such as high carrier recombination rate and low visible light absorption rate, which will reduce the photocatalytic activity.

Contents of the invention

In view of the deficiencies in the prior art, the purpose of the present invention is to provide a preparation method and application of a BiOBr/BiOI/SDBS composite material with microspherical morphology, to solve the problem of degradation of organic matter by BiOBr monomer materials in the prior art. The range of light absorption is limited and the recombination rate of photogenerated electrons and holes is fast.

In order to solve the above technical problems, the present invention adopts the following technical solutions to achieve:

A preparation method of BiOBr/BiOI/SDBS composite material with microspherical morphology, the method uses Bi(NO ₃ )·5H ₂ O as Bi source, SDBS as surfactant, and absolute ethanol as solvent to prepare solution A: With NaBr as the Br source, KI as the I source, and dehydrated alcohol as the solvent, a solution B is prepared; after the solution A and the solution B are respectively ultrasonicated, the solution B is added dropwise to the solution A and stirred; After the end, the mixed solution was put into a closed reaction kettle, and a solvothermal reaction was carried out in an oven to finally obtain a yellow powder BiOBr/BiOI/SDBS photocatalytic material.

The present invention also includes following technical characteristics:

Specifically, the method includes the following steps:

Step 1, prepare Bi source solution A:

Solution A was prepared by dissolving Bi(NO ₃ )·5H ₂ O and SDBS in absolute ethanol and ultrasonication;

Step 2, prepare Br source and I source solution B:

Dissolve NaBr and KI in absolute ethanol, and obtain solution B after ultrasonication;

Step 3, preparing microspherical BiOBr/BiOI/SDBS composite material:

Add the solution B prepared in step 2 dropwise to the solution A prepared in step 1 during the stirring process, and then stir vigorously; put the stirred mixed solution into a closed reaction kettle, and carry out the solvent in the oven Thermal reaction; then naturally cooled, the cooled product was collected by high-speed centrifugation, washed several times with deionized water and absolute ethanol, and then the pure product was dried in an oven and ground with an agate mortar to obtain a yellow powder, which is micro BiOBr/BiOI/SDBS with spherical morphology.

Specifically, in the first step, the ratio of the mass (g) of Bi(NO ₃ )·5H ₂ O, the mass (g) of SDBS and the volume (mL) of absolute ethanol is: 0.485:0.07:10.

Specifically, in the second step, the ratio of the amount (mol) of NaBr, the amount (mol) of KI and the volume (mL) of absolute ethanol is: 1:(0.5-4):10.

Specifically, in the second step, the molar ratio of NaBr and KI is 1:2.

Specifically, the ultrasonic time in the step 1 and step 2 is 10 minutes.

Specifically, the stirring time in the third step is 1 h.

Specifically, the reaction temperature of the solvothermal reaction in the third step is 160° C., and the reaction time is 12 hours.

The BiOBr/BiOI/SDBS composite material with microspherical morphology is prepared by adopting the preparation method of the BiOBr/BiOI/SDBS composite material with microspherical morphology.

The preparation method of the BiOBr/BiOI/SDBS composite material with a microspherical morphology can be used as a photocatalytic material for degrading organic dyes.

Compared with the prior art, the present invention has the following technical effects:

(1) The present invention adopts a simple one-step solvothermal method to prepare the BiOBr/BiOI/SDBS composite material with a microspherical shape. This method has the advantages of simple process, short preparation period and low cost.

(2) The BiOBr/BiOI/SDBS microspheres prepared by the present invention have a diameter of 1-1.5 μm, have larger specific surface area and voids, can absorb more visible light, and fully contact with organic matter in the photocatalytic reaction.

(3) Compared with other photocatalytic materials, the flaky powder BiOBr/BiOI/SDBS composite material prepared by the present invention has higher stability, and has the advantages of low cost, rich content and non-toxicity.

(4) The BiOBr/BiOI/SDBS composite material prepared by the present invention has very high photocatalytic properties for organic dyes, can completely degrade RHB within 20 minutes, and degrade Congo Red by 99%.

Description of drawings

Fig. 1 is the XRD spectrum of the BiOBr/BiOI/SDBS composite material of microspherical morphology in Example 1.

Fig. 2 is the SEM and Mapping spectrum of the BiOBr/BiOI/SDBS composite material of microspherical morphology in Example 1.

FIG. 3 is the XRD spectrum of the BiOBr/BiOI/SDBS composite material in Example 2.

Figure 4 is the XRD spectrum of the BiOBr/BiOI/SDBS composite material in Example 3.

FIG. 5 is a SEM spectrum of the BiOBr/BiOI/SDBS composite material in Example 2.

Figure 6 is the SEM spectrum of the BiOBr/BiOI/SDBS composite material in Example 3.

Fig. 7 is the spectrum of degrading RHB at different times of the BiOBr/BiOI/SDBS composite material with microspherical morphology in Examples 1-3.

Figure 8 is the photocatalytic spectrum of the degradation of different dyes by BiOBr/BiOI/SDBS in Example 1.

Detailed ways

In order to improve the photocatalytic performance of semiconductor monomers, this program studies a new high-efficiency photocatalyst, among which, the bismuth oxyhalide (BiOX, X=Br, I and Cl) photocatalyst has excellent optical properties, electrical properties, unique layered The structure and strong photocatalytic activity have attracted much attention and attention in the field of photocatalysis. BiOBr is a layered semiconductor material with a narrow bandgap and an orthofluoropyronite (PbFCl) structure belonging to the tetragonal crystal system. BiOBr has a symmetry of D4 h and a space group of P4 nmm, belonging to a tetragonal crystal structure. This special crystal structure can make BiOBr have more suitable bandgap width, wider visible light response range, better electrical conductivity and more efficient quantum efficiency. Due to its unique layered structure, high stability and narrow bandgap, it has been widely used in the fields of photocatalysis and photoelectrocatalysis. However, the light absorption range of BiOBr material is limited, and the characteristics of fast electron-hole recombination rate make it still have a big gap in practical application. Therefore, this scheme chooses BiOI with similar characteristics to compound it, and tries to take advantage of the characteristics of BiOX without using other semiconductors. Both BiOBr(2.73eV) and BiOI(1.75eV) have narrow band gaps, while BiOCl(3.24eV) has wider band gaps. In addition, BiOI has the strongest absorption in the visible region. Therefore, this project chooses BiOBr and BiOI whose microstructure is easier to adjust to match the energy band potential and monitor their photocatalytic activity. Therefore, in this experiment, BiOBr/BiOI/SDBS composites were prepared by solvothermal method, and their photocatalytic properties for degrading different dyes were studied, which is of great significance for protecting the environment and water resources, and promoting the development of green ecology.

The present invention provides a preparation method of a BiOBr/BiOI/SDBS composite material with a microspherical morphology. In the method, Bi(NO ₃ )·5H ₂ O is used as a Bi source, SDBS is used as a surfactant, and absolute ethanol is used as a solvent. Solution A is prepared; with NaBr as the Br source, KI as the I source, and absolute ethanol as the solvent, solution B is prepared; after solution A and solution B are respectively ultrasonicated, solution B is added dropwise to solution A and carried out Stirring; after the stirring is completed, put the mixed solution into a closed reaction kettle, and carry out a solvothermal reaction in an oven, and finally obtain a yellow powder BiOBr/BiOI/SDBS photocatalytic material.

The method includes the following steps:

Step 1, prepare Bi source solution A:

Solution A was prepared by dissolving Bi(NO ₃ )·5H ₂ O and SDBS in absolute ethanol and ultrasonication;

Step 2, prepare Br source and I source solution B:

Dissolve NaBr and KI in absolute ethanol, and obtain solution B after ultrasonication;

Step 3, preparing microspherical BiOBr/BiOI/SDBS composite material:

Add the solution B prepared in step 2 dropwise to the solution A prepared in step 1 during the stirring process, and then stir vigorously; put the stirred mixed solution into a closed reaction kettle, and carry out the solvent in the oven Thermal reaction; then naturally cooled, the cooled product was collected by high-speed centrifugation, washed several times with deionized water and absolute ethanol, and then the pure product was dried in an oven and ground with an agate mortar to obtain a yellow powder, which is micro BiOBr/BiOI/SDBS with spherical morphology.

In step 1, the mass ratio of Bi(NO ₃ )·5H ₂ O (g), SDBS mass (g) and absolute ethanol volume (mL) is 0.485:0.07:10.

In step 2, the ratio of the amount of substance (mol) of NaBr, the amount of substance of KI (mol) and the volume of absolute ethanol (mL) is: 1:(0.5-4):10.

Preferably, in step 2, the molar ratio of NaBr and KI is 1:2.

The ultrasonic time in step 1 and step 2 is 10 min.

The stirring time in step 3 is 1 h.

The reaction temperature of the solvothermal reaction in step 3 is 160° C., and the reaction time is 12 hours.

The invention also provides a BiOBr/BiOI/SDBS composite material with a microspherical shape, which is prepared by the preparation method of the BiOBr/BiOI/SDBS composite material with a microspherical shape.

Preparation method of BiOBr/BiOI/SDBS composite material with microspherical morphology The prepared BiOBr/BiOI/SDBS composite material with microspherical morphology is used as a photocatalytic material for the degradation of organic dye RHB.

Specific embodiments of the present invention are provided below, and it should be noted that the present invention is not limited to the following specific embodiments, and all equivalent transformations done on the basis of the technical solutions of the present application all fall within the scope of protection of the present invention.

Example 1:

The present embodiment provides a kind of preparation method of BiOBr/BiOI/SDBS composite material with microspherical shape, and this method specifically comprises the following steps:

Step 1, prepare Bi source solution A:

Weigh 0.485g of Bi(NO ₃ )·5H ₂ O and 0.07g of SDBS and dissolve it in 10mL of absolute ethanol, and after 10min of ultrasonication, a solution A is prepared;

Step 2, prepare Br source and I source solution B:

Weigh 0.025g of NaBr and 0.083g of KI (the molar ratio of Br and I is 1:2) and dissolve them in 10mL of absolute ethanol, and after ultrasonication for 10min, solution B is prepared;

Step 3, making microspherical BiOBr/BiOI/SDBS material:

Add the solution B prepared in step 2 dropwise to the solution A prepared in step 1 during the stirring process, and then carry out vigorous stirring for 1 hour; put the stirred mixed solution into a closed reaction kettle, and carry out in the oven Solvothermal reaction at 160°C for 12 hours; then naturally cooled, the cooled product was collected by high-speed centrifugation, washed several times with deionized water and absolute ethanol, and then the pure product was dried in an oven and ground with an agate mortar to obtain The yellow powder is BiOBr/BiOI/SDBS with a microspherical shape; the photocatalytic performance of the obtained material is characterized by the photocatalytic performance test.

Figure 1 is the XRD spectrum of the BiOBr/BiOI/SDBS composite material with microspherical morphology. After comparing Figure 1 with the standard card JCPDS 73-2061 of BiOBr and the JCPDS 73-2062 spectrum of BiOI, it can be seen that due to the diffraction of BiOBr and BiOI The peaks are similar, and the XRD diffraction peaks of the microspherical BiOBr/BiOI/SDBS composite material finally prepared in this example are the result of phase miscibility between BiOBr and BiOI. When the diffraction peaks appear at 2θ=19.86°, 25.18°, 30.16°, 32.3°, 38.08°, 46.04°, 56.02°, 67.16°, 76.26°, after comparing with BiOBr and BiOI standard cards, the results all correspond to (001 ), (011), (012), (110), (112), (020), (212), (220), (130) crystal planes, the diffraction peaks are strong and narrow. It is fully explained that the prepared material is composed of BiOBr and BiOI, and no other impurities appear.

Adopt the preparation method of the BiOBr/BiOI/SDBS composite material of the microspherical morphology in this embodiment, as shown in Figure 2, the BiOBr/BiOI/SDBS composite material of the microspherical morphology finally made has more regular microspheres Flower-like structure, the average particle size of the microsphere is about 0.5-1 μm, and the maximum particle size is less than 1.5 μm. It can be found from the Mapping diagram that Bi, Br, I and O are uniformly distributed on the microspheres, which further proves that the composite material is composed of BiOBr and BiOI.

The photocatalytic degradation experiment was carried out on the BiOBr/BiOI/SDBS composite material prepared under the optimized process and two control groups. The time interval of 4min was selected to take 5mL of the pollutant solution in the catalytic process, the solution was centrifuged, and the supernatant was taken Perform an absorbance test. The formula for calculating the degradation rate of specific pollutants is as follows:

D=C/C ₀

Among them, D is the photocatalytic degradation rate, C ₀ is the concentration of the pollutant solution at the initial time, and C is the concentration of the solution at time t. The composite photocatalyst prepared under the optimized process was used to degrade the RHB solution, and the test results are shown in Figure 7. Among them, taking time 0 as the node, the left side corresponds to the dark reaction stage in the photocatalysis experiment, and the right side corresponds to the degradation process after the visible light source is turned on. It can be seen from the figure that in the dark reaction, the adsorption degree of the BiOBr/BiOI/SDBS composite material prepared in Example 1 is less than 10%, and the photocatalytic rate is the fastest in the light reaction, and the degradation rate reaches 99% in 20 minutes. Combining with Figure 2, it can be seen that the BiOBr/BiOI/SDBS composite material with microspherical morphology forms a relatively dispersed microspherical structure, and the average particle size is small, which is conducive to increasing the specific surface area and fully contacting with organic pollutants. In addition, the large gap between each nanosheet can absorb more visible light during photoreaction, thereby enhancing the photocatalytic performance.

Figure 8 is the photocatalytic spectrum of the degradation of different dyes by the BiOBr/BiOI/SDBS composite material with microsphere shape. It can be concluded that under visible light, the BiOBr/BiOI/SDBS composite material can degrade 99% of RHB, 89% of Congo red and 83% of methylene blue under visible light. The BiOBr/BiOI/SDBS composite has a high photocatalytic degradation ability for various organic dyes.

Example 2:

The present embodiment provides a kind of preparation method of BiOBr/BiOI/SDBS composite material with microspherical appearance, this method is basically the same as the preparation method of Example 1, the difference is that the molar ratio of Br and I in step 2 is 1 : 0.5.

Using the preparation method of the BiOBr/BiOI/SDBS composite material in this example, as shown in Figure 3 and Figure 5, the XRD pattern can prove that BiOBr/BiOI/SDBS is composed of BiOBr and BiOI. The final BiOBr/BiOI/SDBS composite material has a relatively dense microspherical structure, and the nanosheets of the microspherical structure have a higher degree of aggregation and smaller gaps between the nanosheets.

Example 3:

The present embodiment provides a kind of preparation method of BiOBr/BiOI/SDBS composite material with microspherical appearance, this method is basically the same as the preparation method of Example 1, the difference is that the molar ratio of Br and I in step 2 is 1 :4.

Adopt the preparation method of BiOBr/BiOI/SDBS composite material in the present embodiment, as shown in Figure 4 and Figure 6, can prove in XRD pattern that BiOBr/BiOI/SDBS is made up of BiOBr and BiOI, and by comparing Example 1 and implementation From the XRD spectrum of Example 2, it can be seen that the higher the ratio of I, the closer the XRD diffraction peak of the BiOBr/BiOI/SDBS composite material is to the standard card spectrum of BiOI. The finally prepared BiOBr/BiOI/SDBS composite material has a relatively loose microspherical structure, and the aggregation degree of the nanosheets of the microspherical structure is lower, and the gap between the nanosheets is larger.

From Examples 1-3, the following conclusions can be drawn:

From the analysis of the XRD spectrum, it can be seen that as the content of I element in the BiOBr/BiOI/SDBS composite material is higher, the two diffraction peaks (012) and (110) are closer to the standard card of BiOI, on the contrary, the Br element in the composite material The higher the content, the closer the two diffraction peaks (012) and (110) are to the standard card of BiOBr. This result shows that the ratio of Br and I will affect the position of the XRD diffraction peak, indicating that BiOBr and BiOI are successfully composited. From the morphology in SEM, it can be concluded that the higher the content of I element in the composite material, the larger the pores of the nanosheets in the BiOBr/BiOI/SDBS microspheres, and the looser the degree of aggregation. When the ratio of Br and I was (1:2), the photocatalytic efficiency of BiOBr/BiOI/SDBS microspheres to degrade the organic dye RHB was the highest, and it could be degraded almost completely within 20 min.

In summary, the preparation method of the BiOBr/BiOI/SDBS photocatalytic material with the microspherical morphology of the present invention is a solvothermal method, and the BiOBr/BiOI/SDBS microspheres are formed by gathering thinner nanosheets, and there are large gaps between the nanosheets. The voids can absorb more visible light, and the microspheres are smaller in diameter and evenly distributed, which is conducive to better contact with organic pollutants, thereby improving the photocatalytic performance. Compared with other ratios of BiOBr/BiOI/SDBS composite materials, the photocatalytic efficiency of Example 1 is the highest, and the optimal ratio in the preparation process is determined. The microspherical BiOBr/BiOI/SDBS photocatalytic material obtained based on this method is of great significance for the development of photocatalytic materials with novel morphology and excellent performance.

Claims (10)

1. a kind of preparation method with the BiOBr/BiOI/SDBS composite material of microspherical appearance, it is characterized in that, this method is Bi source with Bi(NO ₃ ) 5H ₂ O, SDBS is tensio-active agent, dehydrated alcohol As a solvent, solution A was prepared; with NaBr as the source of Br, KI as the source of I, and absolute ethanol as the solvent, solution B was prepared; after ultrasonicating solution A and solution B respectively, solution B was added dropwise to solution A After stirring, put the mixed solution into a closed reaction kettle, and carry out solvothermal reaction in an oven, and finally obtain a yellow powder BiOBr/BiOI/SDBS photocatalytic material. 2. the preparation method of the BiOBr/BiOI/SDBS composite material with microspherical appearance as claimed in claim 1, is characterized in that, the method comprises the following steps: Step 1, prepare Bi source solution A: Solution A was prepared by dissolving Bi(NO ₃ )·5H ₂ O and SDBS in absolute ethanol and ultrasonication; Step 2, prepare Br source and I source solution B: Dissolve NaBr and KI in absolute ethanol, and obtain solution B after ultrasonication; Step 3, preparing microspherical BiOBr/BiOI/SDBS composite material: Add the solution B prepared in step 2 dropwise to the solution A prepared in step 1 during the stirring process, and then stir vigorously; put the stirred mixed solution into a closed reaction kettle, and carry out the solvent in the oven Thermal reaction; then naturally cooled, the cooled product was collected by high-speed centrifugation, washed several times with deionized water and absolute ethanol, and then the pure product was dried in an oven and ground with an agate mortar to obtain a yellow powder, which is micro BiOBr/BiOI/SDBS with spherical morphology. 3. the preparation method of the BiOBr/BiOI/SDBS composite material with microspherical morphology as claimed in claim 2, is characterized in that, in described step one, the mass (g) of Bi(NO ₃ )·5H ₂ O , The ratio of the mass (g) of SDBS to the volume (mL) of absolute ethanol is: 0.485:0.07:10. 4. the preparation method of the BiOBr/BiOI/SDBS composite material with microspherical morphology as claimed in claim 2, is characterized in that, in described step 2, the amount of substance (mol) of NaBr, the amount of substance of KI (mol) and the volume (mL) of absolute ethanol are used in the following ratio: 1:(0.5～4):10. 5. the preparation method of the BiOBr/BiOI/SDBS composite material with microspherical morphology as claimed in claim 4, is characterized in that, in described step 2, the mol ratio of NaBr and KI is 1:2. 6. the preparation method of the BiOBr/BiOI/SDBS composite material with microspherical morphology as claimed in claim 2, is characterized in that, the ultrasonic time in described step 1 and step 2 is 10min. 7. The preparation method of the BiOBr/BiOI/SDBS composite material with microspherical morphology as claimed in claim 2, characterized in that, the stirring time in the step 3 is 1h. 8. the preparation method of the BiOBr/BiOI/SDBS composite material with microspherical morphology as claimed in claim 2, is characterized in that, the reaction temperature of the solvothermal reaction in the described step 3 is 160 ℃, and the reaction time is 12h . 9. The BiOBr/BiOI/SDBS composite material with microspherical morphology is characterized in that, the preparation method of the BiOBr/BiOI/SDBS composite material with microspherical morphology described in claim 3 to 8 is adopted get. 10. The BiOBr/BiOI/SDBS composite material with microspherical morphology prepared by the preparation method of the BiOBr/BiOI/SDBS composite material with microspherical morphology according to any one of claims 3 to 8 is used as photocatalytic material Applications for the degradation of organic dyes.

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