BiOBr / ZIF-67 composite material and application thereof

Abstract

The invention belongs to the technical field of photocatalysis, and particularly relates to a BiOBr / ZIF-67 composite material and application thereof. The BiOBr / ZIF-67 composite material provided by the invention is obtained by mechanically mixing the BiOBr powder and the ZIF-67 powder, and the compounding mode not only can utilize the porous structure of the ZIF-67 to improve the specific surface area and the light absorption capacity of a photocatalyst, but also can promote the separation and transmission of photon-generated carriers through an interface synergistic effect, so that the photocatalytic degradation efficiency is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of photocatalysis, and specifically relates to a BiOBr / ZIF-67 composite material and application thereof. Background Art

[0002] In recent years, with the continuous increase in industrial output value, how to efficiently and environmentally treat industrial wastewater while producing and consuming products is one of the problems that needs to be solved urgently. Most industrial wastewaters have different degrees of physiological toxicity, such as organic dyes such as rhodamine B, methyl orange and methylene blue contained in printing and dyeing wastewater; antibiotics and anti-inflammatory drugs such as tetracycline and ibuprofen contained in pharmaceutical wastewater; polycyclic aromatic hydrocarbons, bisphenols and other benzene series contained in petrochemical wastewater. The above organic matter and related by-products will react and transform through various environmental media in the water body, which can easily cause harmful effects on the human body and the natural environment.

[0003] At present, the methods for treating industrial wastewater include adsorption, chemical oxidation, biodegradation, photocatalysis, etc. Photocatalytic technology is the use of solar energy for energy conversion at room temperature and pressure. It has the characteristics of low cost and no pollution. Therefore, photocatalytic technology is considered to be a promising technical strategy to alleviate the increasingly serious environmental pollution. However, many photocatalytic materials show low photocatalytic efficiency due to problems such as wide band gap, fast electron-hole pair recombination rate and low visible light utilization, which hinders the pace of their engineering application. Therefore, it is currently necessary to study new photocatalysts to improve the performance of photocatalytic treatment of industrial wastewater.

[0004] Bismuth oxybromide (BiOBr) is a new type of visible light responsive photocatalyst with a band gap of about 2.7 eV. It has the disadvantage of a low separation rate of photogenerated electron-hole pairs, which leads to low photocatalytic degradation efficiency and greatly limits its application in the field of photocatalysis. Summary of the invention

[0005] Therefore, the technical problem to be solved by the present invention is to overcome the defect of low photocatalytic degradation efficiency of BiOBr in the prior art, thereby providing a BiOBr / ZIF-67 composite material and application thereof.

[0006] To this end, the present invention provides the following technical solutions.

[0007] In a first aspect, the present application provides a BiOBr / ZIF-67 composite material, wherein the BiOBr / ZIF-67 composite material is obtained by mechanically mixing BiOBr powder and ZIF-67 powder.

[0008] In an optional embodiment, the weight ratio of the BiOBr powder to the ZIF-67 powder is (8.9-9.1): (0.9-1.1).

[0009] In an alternative embodiment, the specific surface area of the BiOBr / ZIF-67 composite material is 100 - 312 m 2 / g.

[0010] In an alternative embodiment, the preparation process of the BiOBr powder includes:

[0011] Mixing a bromide salt solution with a bismuth salt solution and performing a first reaction to obtain a first reaction product;

[0012] Collecting the white precipitate in the first reaction product and performing a first washing and a first drying.

[0013] In an alternative embodiment, the preparation process of the ZIF-67 powder includes:

[0014] Adding a 2-methylimidazole solution to a cobalt nitrate solution under stirring conditions and performing a second reaction to obtain a second reaction product;

[0015] Collecting the purple precipitate in the second reaction product and performing a second washing and a second drying.

[0016] In a second aspect, the present application provides the use of the above BiOBr / ZIF-67 composite material in the preparation of a photocatalyst.

[0017] In a third aspect, the present application provides a photocatalyst, which comprises the above BiOBr / ZIF-67 composite material.

[0018] In a fourth aspect, the present application provides the use of the above BiOBr / ZIF-67 composite material in sewage treatment.

[0019] In an alternative embodiment, the sewage treatment includes degrading antibiotic pollutants and / or dye pollutants in water bodies.

[0020] In a fifth aspect, the present application provides a sewage treatment agent, which comprises the above BiOBr / ZIF-67 composite material.

[0021] The technical solution of the present invention has the following advantages:

[0022] The BiOBr / ZIF-67 composite material provided by the present invention is obtained by mechanically mixing BiOBr powder and ZIF-67 powder. This composite method can not only utilize the porous structure of ZIF-67 to increase the specific surface area and light absorption ability of the photocatalyst, but also promote the separation and transport of photo-generated carriers through interfacial synergistic effects, thereby improving the photocatalytic degradation efficiency.

[0023] Specifically, the BiOBr / ZIF-67 composite material is obtained by mechanically mixing BiOBr powder and ZIF-67 powder. This composite method can simply and efficiently achieve the tight combination of the two under mild conditions by in-situ compounding BiOBr and ZIF-67, avoiding the traditional high-temperature calcination or complex post-treatment process, while retaining the excellent properties of BiOBr and ZIF-67. Therefore, this composite method can not only fully exert the photocatalytic activity of BiOBr, but also utilize the porous structure of ZIF-67 to enhance the adsorption capacity of BiOBr for organic pollutants, thereby achieving efficient degradation of refractory organic pollutants in sewage.

[0024] In addition, through research, it is found that the BiOBr / ZIF-67 composite material obtained by the composite method of this application has abundant oxygen vacancies, which can further improve its photocatalytic degradation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0026] Figure 1 is the XRD pattern of BiOBr / ZIF-67 prepared in Example 1 of the present invention;

[0027] Figure 2 is the scanning electron microscope (SEM) image of BiOBr / ZIF-67 prepared in Example 1 of the present invention;

[0028] Figure 3 is the N 2 adsorption-desorption isotherm diagram of BiOBr / ZIF-67 prepared in Example 1 of the present invention;

[0029] Figure 4 is the electron spin resonance spectrometer (ESR) test diagram of BiOBr / ZIF-67 prepared in Example 1 of the present invention;

[0030] Figure 5 is the change curve of the degradation rate of tetracycline hydrochloride with time for BiOBr / ZIF-67-1, BiOBr, ZIF-67 and without catalyst in Experimental Example 1 of the present invention;

[0031] Figure 6Photocatalytic activities (a) and first-order reaction kinetic fitting curves (b) of BiOBr / ZIF-67-1, BiOBr, ZIF-67, and without catalyst for tetracycline hydrochloride in Experimental Example 1 of the present invention;

[0032] Figure 7 Variation curves of the degradation rates of BiOBr / ZIF-67-1, BiOBr, ZIF-67, and without catalyst for rhodamine B with time in Experimental Example 2 of the present invention;

[0033] Figure 8 Photocatalytic activities (a) and first-order reaction kinetic fitting curves (b) of BiOBr / ZIF-67-1, BiOBr, ZIF-67, and without catalyst for rhodamine B in Experimental Example 2 of the present invention. Detailed implementation manners

[0034] The following embodiments are provided to better further understand the present invention, which are not limited to the described optimal implementation manners, and do not constitute limitations on the content and protection scope of the present invention. Any product identical or similar to the present invention obtained by anyone under the inspiration of the present invention or by combining the features of the present invention with those of other existing technologies falls within the protection scope of the present invention.

[0035] For those embodiments where specific experimental steps or conditions are not indicated, the operations or conditions of the conventional experimental steps described in the literature in this field can be followed. For the reagents or instruments whose manufacturers are not indicated, they are all conventional reagent products that can be obtained through commercial purchase.

[0036] Some of the reagents and instruments involved in the present invention are as follows:

[0037] Reagents: The purity of cobalt (II) nitrate hexahydrate, 2-methylimidazole, bismuth (III) nitrate pentahydrate, ethanol, and potassium bromide is 99%. All the drugs do not need further purification and can be directly used in the experiment.

[0038] Instruments: Electronic balance (AL204, METTLER TOLEDO Instruments Co., Ltd., Shanghai); Magnetic stirrer (85-1, Shanghai Sile Instruments Co., Ltd.); Oven (101-1AB, Tianjin Test); Xenon lamp (YM-GHX-XE-300, Shanghai Yuming Instruments Co., Ltd.); Scanning electron microscope (JSM-6700F Microscope, Shenzhen Blue Star Yu Electronics Co., Ltd.); Transmission electron microscope (JEM-2100, JEOL Ltd., Japan); Visible spectrophotometer (723PC, Shanghai Spectrum Instruments Co., Ltd.).

[0039] Example 1

[0040] Prepare the BiOBr / ZIF-67 composite material according to the following method:

[0041] (1) Preparation of BiOBr

[0042] Dissolve 1.455 g of bismuth nitrate pentahydrate (Bi(NO 3 )) 3 ·5H 2 O) in 20 mL of distilled water, place it in an ultrasonic machine and ultrasonicate for 30 min to obtain a bismuth nitrate solution; dissolve 0.357 g of potassium bromide (KBr) in 25 mL of distilled water, add a magnetic stir bar, and stir on a magnetic stirrer for 10 min to obtain a potassium bromide solution; add the bismuth nitrate solution after ultrasonic treatment to the above potassium bromide solution, and stir at room temperature for 3 h to obtain a first reaction product; centrifuge the above first reaction product and collect the resulting white precipitate, wash it twice with distilled water and three times with ethanol, and place the washed product in an oven at 60 °C to dry for 8 h for standby, labeled as BiOBr.

[0043] (2) Preparation of ZIF-67

[0044] Dissolve 0.548 g of cobalt nitrate hexahydrate (Co(NO 3 )) 2 ·6H 2 O) and 4.54 g of 2-methylimidazole (C 4 H 6 N 2 ) in 5 mL and 30 mL of distilled water respectively to obtain a cobalt nitrate solution and a 2-methylimidazole solution; on a magnetic stirrer, add a magnetic stir bar to the cobalt nitrate solution, stir, quickly pour in the 2-methylimidazole solution, and stir at room temperature for 30 min to obtain a second reaction product; centrifuge the above second reaction product and collect the resulting purple precipitate, wash it three times with ethanol, and place the washed product in an oven at 60 °C to dry for 8 h for standby, labeled as ZIF-67.

[0045] (3) Preparation of BiOBr / ZIF-67

[0046] Take 0.1 g of the above ZIF-67 and 0.9 g of the above BiOBr, place them in a mortar for mechanical mixing, and label the resulting product as BiOBr / ZIF-67.

[0047] Characterize the BiOBr / ZIF-67 prepared in this example using an X-ray diffraction (XRD) instrument, and the results are as Figure 1 shown. Figure 1XRD pattern of BiOBr / ZIF-67 prepared in this example. Among them, PDF#09-0393 is the standard diffraction pattern of BiOBr. By comparison, it can be seen that compared with the standard diffraction pattern shown in PDF#09-0393, some diffraction peaks originally belonging to BiOBr on the BiOBr / ZIF-67 pattern disappear, and some other characteristic peaks appear. The position marked by the heart-shaped pattern is the characteristic peak position of ZIF-67, indicating that the target product BiOBr / ZIF-67 is successfully synthesized.

[0048] To further study the morphology of BiOBr / ZIF-67 prepared in this example, the sample was tested by scanning electron microscopy (SEM). BiOBr is a material with photocatalytic activity, while ZIF-67 is a zeolitic imidazolate framework material with a high specific surface area and good pore structure. Figure 2 Scanning electron microscopy (SEM) image of BiOBr / ZIF-67 prepared in this example. Figure 2 It can be seen that the two materials are loaded together and distributed evenly, further indicating that BiOBr / ZIF-67 with a high specific surface area and better pore structure is successfully prepared.

[0049] Figure 3 N 2 adsorption-desorption isotherm diagram of BiOBr / ZIF-67 prepared in this example. Figure 3 It can be seen that the BiOBr / ZIF-67 material shows a typical type IV isotherm, indicating that it has a mesoporous structure, that is, it has a high specific surface area and good mass transfer characteristics. By calculation, the specific surface area of the BiOBr / ZIF-67 material prepared in this example is 207.783 m 2 / g. This curve reflects that after the formation of the heterojunction, the material shows a higher specific surface area, and the higher specific surface area will expose more active sites, which is beneficial to the adsorption of reactants and improves the photocatalytic degradation rate.

[0050] Figure 4 Electron spin resonance spectrometer (ESR) test image of BiOBr / ZIF-67 prepared in this example. It can be seen from the figure that compared with BiOBr, BiOBr / ZIF-67 has a strong signal peak, indicating that CoCo-LDH contains rich oxygen vacancies, and the rich oxygen vacancies can further improve its photocatalytic degradation efficiency.

[0051] Example 2

[0052] The BiOBr / ZIF-67 composite material was prepared according to the method of Example 1, except that in step (3) of this example, the amount of ZIF-67 used was 0.09 g and the amount of BiOBr used was 0.91 g.

[0053] Example 3

[0054] The BiOBr / ZIF-67 composite material was prepared according to the method of Example 1, except that in step (3) of this example, the amount of ZIF-67 used was 0.11 g and the amount of BiOBr used was 0.89 g.

[0055] Comparative Example

[0056] The BiOBr / ZIF-67 composite material was prepared according to the method of Example 1, except that in step (3) of this comparative example, 0.1 g of ZIF-67 and 0.9 g of BiOBr were placed in 25 mL of distilled water and sonicated for 30 min, then placed on a magnetic stirrer and stirred at room temperature for 1 h. Then, the reaction product was centrifuged and the obtained precipitate was collected, washed three times with ethanol, and the washed product was placed in an oven at 60 °C and dried for 8 h for standby.

[0057] Experimental Example 1 Determination of the degradation rate of tetracycline hydrochloride

[0058] The BiOBr / ZIF-67 composite materials prepared in Examples 1-3 were numbered BiOBr / ZIF-67-(1-3) in sequence, and the BiOBr / ZIF-67 composite material prepared in the comparative example was numbered BiOBr / ZIF-67-D. At the same time, BiOBr and ZIF-67 prepared in Example 1 were used as controls, and a blank control (without catalyst) was set. The degradation rate of tetracycline hydrochloride was determined according to the following method:

[0059] Prepare a 20 mg / L tetracycline hydrochloride solution using a 1000 mL volumetric flask. After standing overnight, measure 100 mL of the tetracycline hydrochloride solution and slowly pour it into containers containing 50 mg of each catalyst (the blank control is an empty container). Then place each container on a magnetic stirrer and stir. Adsorb in the dark for 30 min. After completion, take 8 g of the supernatant into a centrifuge tube, and place the remaining solution under a preheated xenon light source and irradiate while stirring. After the irradiation starts, take 8 g of the supernatant from the container into a centrifuge tube every 10 min. The taken solution should be stored in the dark. Stop sampling after 90 min. Centrifuge each centrifuge tube at 10000 r / min for 10 min, take the supernatant, and measure the absorbance of the samples at 357 nm using a visible spectrophotometer in ascending order of concentration to calculate the degradation rate. Calculate the degradation rate of tetracycline hydrochloride for each catalyst at the 10th, 20th, 30th, 40th, 50th, 60th, 70th, 80th, and 90th minutes after the start of light irradiation. The results are shown in Table 1. Among them, the change curves of the degradation rates of BiOBr / ZIF-67-1, BiOBr, ZIF-67, and no catalyst for tetracycline hydrochloride are as Figure 5 shown.

[0060] Table 1 Degradation rates of each catalyst for tetracycline hydrochloride (%)

[0061] 10 min 20 min 30 min 40 min 50 min 60 min 70 min 80 min 90 min BiOBr / ZIF-67-1 36.96 62.88 76.32 81.76 86.88 89.44 93.20 94.80 95.00 BiOBr / ZIF-67-2 30.56 50.89 63.50 69.60 71.78 72.71 73.66 74.89 75.57 BiOBr / ZIF-67-3 30.78 51.98 68.70 70.60 73.19 74.72 76.78 78.10 79.90 BiOBr / ZIF-67-D 30.45 49.46 60.68 67.68 68.67 69.75 70.67 71.89 72.37 BiOBr 5.40 10.90 15.70 19.40 23.80 27.60 34.10 39.90 45.60 ZIF-67 21.60 36.50 45.70 51.20 55.20 59.10 58.72 62.52 65.90 No catalyst 0.31 0.62 0.94 1.25 1.56 1.87 2.19 2.50 2.810

[0062] Use the ratio (C t of the concentration of tetracycline hydrochloride at any time to its initial concentration C 0 (C t / C 0 ) to characterize the photocatalytic activity of each catalyst for the photocatalytic degradation of tetracycline hydrochloride. The smaller the C t / C 0 value, the better the photocatalytic activity. Perform kinetic fitting according to the following formula to characterize the photocatalytic degradation ability of each catalyst:

[0063] ln(C 0 / C t ) = KT;

[0064] where T is the time of photocatalytic degradation, and the K value represents the first-order reaction rate constant. Generally speaking, the larger the K value, the better the photocatalytic degradation performance of the sample.

[0065] The photocatalytic activities of each catalyst for the photocatalytic degradation of tetracycline hydrochloride are shown in Table 2. Among them, the photocatalytic activities of BiOBr / ZIF-67-1, BiOBr, ZIF-67, and no catalyst for tetracycline hydrochloride are as Figure 6as shown in (a) therein. The degradation reaction rate constant K of each catalyst for tetracycline hydrochloride is shown in Table 3. Among them, the first-order reaction kinetic fitting curves of BiOBr / ZIF-67-1, BiOBr, ZIF-67, and the catalyst-free for the photocatalysis of tetracycline hydrochloride are as Figure 6 shown in (b) therein.

[0066] Table 2 Photocatalytic activities of various catalysts for the photocatalytic degradation of tetracycline hydrochloride

[0067]

[0068] Table 3 Degradation reaction rate constant K of each catalyst for tetracycline hydrochloride

[0069] <![CDATA[First-order reaction rate constant K (min -1 )]]> BiOBr / ZIF-67-1 0.03374 BiOBr / ZIF-67-2 0.01446 BiOBr / ZIF-67-3 0.01628 BiOBr / ZIF-67-D 0.01300 BiOBr 0.01088 ZIF-67 0.00647 No catalyst 0.00032

[0070] It can be seen that compared with the composite method in aqueous solution, after BiOBr and ZIF-67 are combined by the mechanical composite method of the present invention, the photocatalytic performance of the material can be significantly improved, and the degradation rate of tetracycline hydrochloride can be increased.

[0071] Experimental Example 2 Determination of the degradation rate of Rhodamine B

[0072] The BiOBr / ZIF-67 composite materials prepared in Examples 1-3 were numbered BiOBr / ZIF-67-(1-3) in sequence, and the BiOBr / ZIF-67 composite material prepared in the comparative example was numbered BiOBr / ZIF-67-D. The degradation rate of Rhodamine B was determined according to the following method:

[0073] 100 mL of a rhodamine B solution with a concentration of 20 mg / L was slowly poured into 50 mg of the catalyst under stirring, stirred on a magnetic stirrer, adsorbed in the dark for 30 min. After completion, 8 g of the supernatant was taken into a centrifuge tube, and the remaining solution was placed under the preheated xenon lamp source and irradiated while stirring. After the irradiation started, 8 g of the supernatant was taken into a centrifuge tube every two minutes, and attention should be paid to storing the taken solution in the darkroom. Sampling was stopped after 8 min. Each centrifuge tube was centrifuged at 10,000 r / min for 3 min, and the supernatant was taken to measure the absorbance of the sample at 520 nm with a visible spectrophotometer in ascending order of concentration, and the degradation rate was calculated. The degradation rates of rhodamine B of each catalyst at the 2nd, 4th, 6th, and 8th minutes after the start of light irradiation were calculated respectively. The results are shown in Table 4. Among them, the curves of the degradation rates of BiOBr / ZIF-67-1, BiOBr, ZIF-67, and the catalyst-free for rhodamine B changing with time are as Figure 7 shown.

[0074] Table 4 Degradation rates of various catalysts for Rhodamine B

[0075] 2 min 4 min 6 min 8 min BiOBr / ZIF-67-1 58.36％ 81.64％ 95.97％ 98.7％ BiOBr / ZIF-67-2 53.3％ 75.5％ 94.8％ 96.5％ BiOBr / ZIF-67-3 52.1％ 72.3％ 94.1％ 95.2％ BiOBr / ZIF-67-D 51.7％ 67.8％ 93.7％ 95.6％ BiOBr 39.77％ 63.45％ 83.71％ 94.3％ ZIF-67 9.53％ 19.63％ 26.54％ 37.9％ No catalyst 0.75％ 1.69％ 2.45％ 2.82％

[0076] At any given time, the concentration C of rhodamine B t and its initial concentration C 0 The ratio (C t / C 0 ) characterizes the photocatalytic activity of each catalyst for the photocatalytic degradation of rhodamine B. The smaller the C t / C 0 value, the better the photocatalytic activity. Kinetic fitting is performed according to the following formula to characterize the photocatalytic degradation ability of each catalyst:

[0077] ln(C 0 / C t ) = KT;

[0078] where T is the time of photocatalytic degradation, and the K value represents the first-order reaction rate constant. Generally speaking, the larger the K value, the better the photocatalytic degradation performance of the sample.

[0079] The photocatalytic activities of each catalyst for the photocatalytic degradation of rhodamine B are shown in Table 5. Among them, the photocatalytic activities of BiOBr / ZIF-67-1, BiOBr, ZIF-67, and the catalyst-free for rhodamine B are as Figure 8 shown in (a) of. The degradation reaction rate constants K of each catalyst for rhodamine B are shown in Table 6. Among them, the first-order reaction kinetic fitting curves of BiOBr / ZIF-67-1, BiOBr, ZIF-67, and the catalyst-free for the photocatalysis of rhodamine B are as Figure 8 shown in (b) of.

[0080] Table 5 Photocatalytic activities of each catalyst for the photocatalytic degradation of rhodamine B

[0081]

[0082]

[0083] Table 6 Degradation reaction rate constants K of each catalyst for rhodamine B

[0084] <![CDATA[First-order reaction rate constant K (min -1 )]]> BiOBr / ZIF-67-1 0.54775 BiOBr / ZIF-67-2 0.44499 BiOBr / ZIF-67-3 0.40836 BiOBr / ZIF-67-D 0.4142 BiOBr 0.0581 ZIF-67 0.3522 No catalyst 0.00375

[0085] It can be seen that by using the composite method of the present invention to composite BiOBr and ZIF-67, the photocatalytic performance of the material can be significantly improved, and the degradation rate of rhodamine B can be increased.

[0086] In summary, the present invention designs and provides a composite material based on BiOBr and ZIF-67. Through photocatalytic technology, a BiOBr / ZIF-67 composite material with a high specific surface area, strong adsorption and efficient photocatalytic performance is prepared. The photocatalytic activity of the catalyst is evaluated by the performance of photocatalytic degradation of pollutants such as antibiotics and dyes in water. Through characterizations such as transmission electron microscopy, X-ray diffractometer, scanning electron microscopy, BET, etc., the structure and composition of the material are deeply explored. The experimental results show that the prepared BiOBr / ZIF-67 composite material has excellent photocatalytic degradation performance. The degradation rate of antibiotic pollutants such as tetracycline hydrochloride in water is as high as 95% within 90 minutes, and the degradation rate of dye pollutants such as rhodamine B in water can be as high as 98.7% within 8 minutes. It is found that after BiOBr with good photocatalytic activity is combined with ZIF-67 with a high specific surface area and pore structure, it exhibits excellent performance in the fields of photocatalysis, material adsorption, separation, and photogenerated carrier separation ability, providing a basis for efficient photocatalytic degradation of sewage.

[0087] Obviously, the above embodiments are merely examples given for clear illustration and not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. A BiOBr / ZIF-67 composite material, characterized in that: The BiOBr / ZIF-67 composite material is obtained by mechanically mixing BiOBr powder and ZIF-67 powder.

2. The BiOBr / ZIF-67 composite material according to claim 1, characterized in that The weight ratio of the BiOBr powder to the ZIF-67 powder is (8.9-9.1):(0.9-1.1).

3. The BiOBr / ZIF-67 composite material according to claim 1, characterized in that The specific surface area of ​​the BiOBr / ZIF-67 composite material is 100 to 312 m 2 / g.

4. The BiOBr / ZIF-67 composite material according to claim 1, characterized in that The preparation process of the BiOBr powder comprises: mixing a bromine salt solution and a bismuth salt solution and performing a first reaction to obtain a first reaction product; The white precipitate in the first reaction product is collected, and subjected to a first washing and a first drying.

5. The BiOBr / ZIF-67 composite material according to claim 1, characterized in that The preparation process of the ZIF-67 powder comprises: Under stirring conditions, adding the 2-methylimidazole solution to the cobalt nitrate solution and performing a second reaction to obtain a second reaction product; The purple precipitate in the second reaction product is collected, and subjected to a second washing and a second drying.

6. Use of the BiOBr / ZIF-67 composite material according to any one of claims 1 to 5 in the preparation of a photocatalyst.

7. A photocatalyst, characterized in that: The photocatalyst comprises the BiOBr / ZIF-67 composite material according to any one of claims 1 to 5.

8. Use of the BiOBr / ZIF-67 composite material according to any one of claims 1 to 6 in sewage treatment.

9. The use according to claim 8, characterized in that: The sewage treatment includes degrading antibiotic pollutants and / or dye pollutants in the water body.

10. A sewage treatment agent, characterized in that: The sewage treatment agent comprises the BiOBr / ZIF-67 composite material according to any one of claims 1 to 5.

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