阅读说明：本技术 一种MoS2/BiVO4异质结复合光催化剂的制备方法及其应用 (MoS2/BiVO4Preparation method and application of heterojunction composite photocatalyst ) 是由 刘馨琳 徐玲艳 刘倩 朱炫 逯子扬 于泽惠 周国生 朱晓蝶 李武举 于 2019-08-02 设计创作，主要内容包括：本发明属于环境材料制备技术领域,涉及水热法合成MoS_2/BiVO_4复合光催化剂的制备方法及其用途；步骤为：首先制备MoS_2纳米片,然后将硝酸铋和聚乙烯吡咯烷酮加入乙二醇中,超声分散溶解,得到混合溶液A；将NH_4VO_3加入去离子水中,超声分散溶解,得到混合溶液B；在磁力搅拌下将步MoS_2纳米片、3-巯基丙酸、混合溶液B缓慢加入到混合溶液A中,混合液转移到高压釜中进行恒温反应,反应后进行离心,得到沉淀物经清洗、干燥得到MoS_2/BiVO_4复合光催化剂；本发明操作简便,安全环保,催化剂形貌表现出0D BiVO_4/2DMoS_2的特点,催化剂的活性比表面积大,用于降解环境废水中的有害物质。(The invention belongs to the technical field of preparation of environmental materials, and relates to synthesis of MoS by a hydrothermal method 2 /BiVO 4 A preparation method and application of the composite photocatalyst; the method comprises the following steps: first, MoS is prepared 2 nano-sheets, adding bismuth nitrate and polyvinylpyrrolidone into ethylene glycol, and performing ultrasonic dispersion and dissolution to obtain a mixed solution A; reacting NH 4 VO 3 Adding the mixture into deionized water, and performing ultrasonic dispersion and dissolution to obtain a mixed solution B; under the magnetic stirring, MoS 2 Slowly adding the nano-sheet, the 3-mercaptopropionic acid and the mixed solution B into the mixtureIn the solution A, the mixed solution is transferred into an autoclave for constant temperature reaction, centrifugation is carried out after the reaction, and the obtained precipitate is washed and dried to obtain MoS 2 /BiVO 4 A composite photocatalyst; the method is simple and convenient to operate, safe and environment-friendly, and the catalyst has a morphology of 0D BiVO 4 /2DMoS 2 The catalyst has the characteristics of large active specific surface area and is used for degrading harmful substances in environmental wastewater.)

1. A preparation method of a MoS2/BiVO4 heterojunction composite photocatalyst is characterized by comprising the following steps:

Step 1, mixing (NH)₄)₆Mo₇O₂₄﹒4H₂O and CH₄N₂s, adding the mixture into deionized water, and stirring and dissolving the mixture to form a uniform solution; then transferring the mixture into a high-pressure kettle for constant-temperature reaction, naturally cooling the mixture to room temperature after the reaction, repeatedly washing the obtained product with water and ethanol, drying the washed product, grinding the dried product into fine powder to obtain MoS₂Dispersing the powder in a mixed solution of water and ethanol, ultrasonically stirring to obtain a suspension, and ultrasonically treating the suspension to obtain the final productThe sheet with the aggregated precipitates is MoS₂Nanosheets;

Step 2, adding Bi (NO)₃﹒5H₂Adding O and polyvinylpyrrolidone into ethylene glycol, and performing ultrasonic dispersion and dissolution to obtain a mixed solution A; reacting NH₄VO₃Adding the mixture into deionized water, and performing ultrasonic dispersion and dissolution to obtain a mixed solution B; then, the MoS prepared in the step (1) is stirred under magnetic force₂Slowly adding the nanosheets, the 3-mercaptopropionic acid and the mixed solution B into the mixed solution A to obtain a mixed solution C, transferring the mixed solution C into an autoclave for constant-temperature reaction, centrifuging the reacted solution, cleaning the centrifuged precipitate with deionized water and absolute ethyl alcohol, and finally passing through a vacuum drying oven to obtain MoS₂/BiVO₄A composite photocatalyst is provided.

2. The method for preparing the MoS2/BiVO4 heterojunction composite photocatalyst as claimed in claim 1, wherein in step 1, (NH) is added₄)₆Mo₇O₂₄﹒4H₂O、CH₄N₂S and H₂the dosage ratio of O is 0.1 mmol: 3 mmol: 70 mL.

3. The preparation method of the MoS2/BiVO4 heterojunction composite photocatalyst as claimed in claim 1, wherein in the step 1, the temperature of the isothermal thermal reaction is 220-250 ℃, and the reaction time is 20-24 hours.

4. The method for preparing the MoS2/BiVO4 heterojunction composite photocatalyst as claimed in claim 1, wherein the time of ultrasonic stirring is 6-10 h; the ultrasonic treatment time is 20-30 min; the volume ratio of the water to the ethanol is 3: 1.

5. The method for preparing the MoS2/BiVO4 heterojunction composite photocatalyst as claimed in claim 1, wherein in the step 2, Bi (NO) used in the mixed solution A₃﹒5H₂The dosage ratio of O, polyvinylpyrrolidone and glycol is 0.094-0.886 g: 0.4 g: 50 mL.

6. The method for preparing the MoS2/BiVO4 heterojunction composite photocatalyst as claimed in claim 1, wherein in the step 2, NH in the mixed solution B₄VO₃The dosage ratio of the deionized water is 0.0253 g-0.034 g: 30 mL.

7. The method for preparing the MoS2/BiVO4 heterojunction composite photocatalyst as claimed in claim 1, wherein in the step 2, the MoS2/BiVO4 heterojunction composite photocatalyst₂The dosage ratio of the nanosheet to the 3-mercaptopropionic acid to the mixed solution B to the mixed solution A is 5-30 mg: 0.05-0.2: 20-30 mL: 30-50 mL.

8. The method for preparing the MoS2/BiVO4 heterojunction composite photocatalyst as claimed in claim 1, wherein in the step 2, the temperature of the isothermal thermal reaction is 160-200 ℃, and the reaction time is 1-6 h; the centrifugal rotating speed is 8000-10000 r/s, and the time is 3-5 min.

9. The method for preparing the MoS2/BiVO4 heterojunction composite photocatalyst as claimed in claim 1, wherein in the step 2, the prepared MoS is prepared₂/BiVO₄In the composite photocatalyst, MoS₂The mass fraction of (A) is 5-30%.

10. The MoS2/BiVO4 heterojunction composite photocatalyst prepared by the method according to any one of claims 1 to 9 is applied to degradation of tetracycline in wastewater.

Technical Field

The invention belongs to the technical field of preparation of environmental materials, and relates to synthesis of MoS by a hydrothermal method₂/BiVO₄A preparation method and application of the composite photocatalyst.

Background

Antibiotics (Antibiotics) are pathogen-resistant secondary metabolites produced by bacteria, molds and other microorganisms or higher animals and plants, and are chemical substances that interfere with the development of other cells. In the rapidly developing modern society of the pharmaceutical industry, antibiotics are used in a large number in the treatment and defense of diseases in humans and livestock. However, the hazards of antibiotic abuse cannot be ignored: cannot be easily biodegraded and a large amount of remaining waste can flow into the aquatic environment. Various antibiotics existing in the environment promote drug-resistant genes and bacteria to be transferred into human bodies through various different ways, and serious influence is caused on the balance of a natural ecological system and human health. Therefore, how to efficiently treat ecological damage caused by antibiotic residues and solve the problem of food safety caused by antibiotic enrichment effect becomes a key concern of many researchers.

Photocatalytic degradation utilizes solar energy which is easily obtained in natural environment to degrade all toxic and harmful organic substances and part of inorganic substances in water environment. The photocatalysis technology has the characteristics of high catalysis efficiency, simple operation, energy conservation, low cost and the like, and is one of the most effective advanced oxidation technologies in the field of removing aquatic pollutants. As can be seen from the related researches, one of the methods for improving the carrier separation efficiency is to couple two semiconductors, i.e. to form a heterojunction. The heterojunction formed by the extremely poor energy of the two semiconductors can effectively promote the separation, transfer and transfer of electron holes, so that the purpose of inhibiting the recombination of photo-generated electrons and holes is achieved, and the photocatalytic activity is improved.

Molybdenum disulfide (MoS)₂) Is a two-dimensional Transition Metal Disulfide (TMD) having a unique layered structure and specific properties. Recently, some reports have shown that MoS₂Can be used as an effective cocatalyst for photocatalytic hydrogen production and degradation of organic pollutants under visible light irradiation^[1-6]. And MoS₂MoS consisting of weakly coupled S-Mo-S atomic interlayers, stacked face-to-face and weakly interacting₂The lumpy molybdenum disulfide of the layer composition has an extremely adverse effect on the photocatalytic performance, considering the two-dimensional few-layer MoS₂the nano-sheet is a feasible material of a heterojunction, has proper band gap energy of 1.9eV, and has high specific surface area and more edge positions compared with bulk molybdenum disulfide. It has been reported in the literature that oxygen-doped MoS is synthesized by hydrothermal method and chemical plating solution deposition calcination process₂nanosphere/CdS quantum dot/g-C₃N₄The nano-sheet increases more active sites, and the formed heterojunction effectively inhibits the recombination of electron hole pairs; however, the CdS quantum dots have heavy metal ions and are slightly soluble in water due to photo-corrosion, so that secondary pollution is caused.

Bismuth vanadate (BiVO)₄) Has the following advantages: non-toxic, inexpensive and chemically stable; however, BiVO is limited by defects of poor electron-hole pair separation, slow charge carrier mobility, short carrier diffusion length and significant electron-hole recombination during application₄The performance of (c). Because of these problems, if a more efficient photocatalytic system is designed to promote BiVO₄The charge separation of (a) will be of great significance. The heterostructure composite material mentioned above is beneficial to improving the performance and solves the BiVO₄Poor separation of electron-hole pairs and slow charge carrier migration rate. The core-shell is successfully prepared by adopting an in-situ hydrothermal methodNovel heterojunction photocatalyst n-Bivo4@ p-MoS with structure₂However, the core-shell structure catalyst has a smaller active specific surface area than the 0D/2D structure.

disclosure of Invention

The invention aims to prepare MoS by taking a hydrothermal method as a technical means₂/BiVO₄A composite photocatalyst is provided.

The invention is realized by the following technical scheme:

Synthesis of MoS by photolysis deposition method and hydrothermal method₂/BiVO₄The preparation method of the composite photocatalyst comprises the following steps:

Step 1, preparation of MoS₂Nanosheets;

will be (NH)₄)₆Mo₇O₂₄﹒4H₂O and CH₄N₂S, adding the mixture into deionized water, and stirring and dissolving the mixture to form a uniform solution; then transferring the mixture into a high-pressure kettle for constant-temperature reaction, naturally cooling the mixture to room temperature after the reaction, repeatedly washing the obtained product with water and ethanol, drying the washed product, grinding the dried product into fine powder to obtain MoS₂Dispersing the powder in a mixed solution of water and ethanol, performing ultrasonic stirring to obtain a suspension, performing ultrasonic treatment on the suspension to obtain a sheet material with precipitate aggregation, namely MoS₂Nanosheets;

Step 2, MoS preparation₂/BiVO₄The composite photocatalyst comprises:

Mixing bismuth nitrate (Bi (NO)₃﹒5H₂O) and polyvinylpyrrolidone are added into ethylene glycol, and ultrasonic dispersion and dissolution are carried out to obtain a mixed solution A; reacting NH₄VO₃Adding the mixture into deionized water, and performing ultrasonic dispersion and dissolution to obtain a mixed solution B; then, the MoS prepared in the step (1) is stirred under magnetic force₂Slowly adding the nanosheets, the 3-mercaptopropionic acid and the mixed solution B into the mixed solution A to obtain a mixed solution C, transferring the mixed solution C into an autoclave for constant-temperature reaction, centrifuging the reacted solution, cleaning the centrifuged precipitate with deionized water and absolute ethyl alcohol, and finally passing through a vacuum drying oven to obtain MoS₂/BiVO₄A composite photocatalyst is provided.

Preferably, in step 1, the (NH)₄)₆Mo₇O₂₄﹒4H₂O、CH₄N₂S and H₂The dosage ratio of O is 0.1 mmol: 3 mmol: 70 mL.

Preferably, in the step 1, the temperature of the constant-temperature thermal reaction is 220-250 ℃, and the reaction time is 20-24 hours.

Preferably, in the step 1, the ultrasonic stirring time is 6-10 h; the ultrasonic treatment time is 20-30 min.

preferably, in step 1, the volume ratio of the water to the ethanol is 3: 1.

Preferably, in step 2, Bi (NO) used in the mixed solution A₃﹒5H₂The dosage ratio of O, polyvinylpyrrolidone and glycol is 0.094-0.886 g: 0.4 g: 50 mL.

Preferably, in step 2, NH in the mixed solution B₄VO₃The dosage ratio of the deionized water is 0.0253 g-0.034 g: 30 mL.

Preferably, in step 2, the MoS₂The dosage ratio of the nanosheet to the 3-mercaptopropionic acid to the mixed solution B to the mixed solution A is 5-30 mg: 0.05-0.2 mL: 20-30 mL: 30-50 mL.

Preferably, in the step 2, the temperature of the isothermal thermal reaction is 160-200 ℃, and the reaction time is 1-6 h.

Preferably, in the step 2, the rotating speed of the centrifugation is 8000-10000 r/s, and the time is 3-5 min.

Preferably, in step 2, the MoS is prepared₂/BiVO₄In the composite photocatalyst, MoS₂The mass fraction of (A) is 5-30%.

Prepared MoS₂/BiVO₄The composite photocatalyst is used for degrading tetracycline in wastewater.

evaluation of photocatalytic activity: irradiating with visible light lamp in DW-01 type photochemical reactor (purchased from teaching instrument factory of Yangzhou university), adding 100mL tetracycline simulation wastewater into the reactor, measuring initial value, adding 100mg composite photocatalyst, magnetically stirring, starting aeration device, and introducing airKeeping the catalyst in suspension or floating state, sampling and analyzing at 20min interval during illumination process, centrifuging, collecting supernatant, and placing in spectrophotometer lambda_maxAbsorbance was measured at 356nm and by the formula: DR ═ [ (A)₀-A_i)/A₀]X 100% calculating the degradation rate, wherein A₀Absorbance of the tetracycline solution to equilibrium for adsorption, A_iThe absorbance of the tetracycline solution was determined for the timed samples.

Ammonium molybdate tetrahydrate, 3-mercaptopropionic acid, bismuth nitrate pentahydrate, thiourea, ammonium metavanadate and ethylene glycol which are used in the invention are analytically pure, and polyvinylpyrrolidone is super-grade pure and purchased from national chemical reagent company Limited; the tetracycline antibiotic is a standard product and is purchased from Shanghai Shubo bioengineering Co.

Has the advantages that:

the invention realizes the application of MoS₂/BiVO₄For the purpose of degrading antibiotic wastewater by the catalyst; the photocatalyst shows 0D BiVO in appearance by adding 3-mercaptopropionic acid dispersant₄/2D MoS₂The catalyst has the characteristics of large active specific surface area; the degradation rate of the tetracycline antibiotic reaches 68.83 percent within 150 min. The invention takes semiconductor material as photocatalyst, the light excitation wave band is visible light wave band, and the catalytic driving or conversion effect is realized through the interface interaction with the antibiotic wastewater molecules, so that oxygen and water molecules entering the wastewater are excited to form free negative ions with oxidizing property, and further the harmful substances in the environmental wastewater are degraded. When the molybdenum disulfide is prepared by the method, an ultrasonic stirring mode is adopted, the operation is convenient and fast, the cost is low, the solvent selected by ultrasonic is a mixed solution of water and ethanol, the method is non-toxic and harmless, and no additional pollutant is formed.

drawings

FIG. 1 is the MoS prepared in example 5₂/BiVO₄TEM image of composite photocatalyst, and FIG. a is MoS₂The edges of the flower ball are in a thin sheet shape; graph b is BiVO₄Nanoparticles, which are seriously agglomerated because no dispersant is added; FIG. c shows MoS₂/BiVO₄Adding dispersant 3-mercaptopropionic acid and BiVO into a morphology chart of the composite photocatalyst₄The nano particles are uniformly dispersed in the MoS₂On the ball, the successful preparation of the sample is indicated.

FIG. 2 is the MoS prepared in example 5₂/BiVO₄The solid ultraviolet image of the composite photocatalyst shows that the photocatalyst has a good photoresponse interval, BiVO₄Improves MoS by adding₂The sample itself is black in color, and the most preferable example is MoS in a mass fraction of 20 wt%₂/BiVO₄Has a light response intensity higher than MoS₂The sample has obvious response in a visible light region, and the prepared catalyst can effectively carry out photocatalytic reaction in the visible light region.

FIG. 3 is the MoS prepared in example 5₂/BiVO₄The XRD pattern of the composite photocatalyst can show MoS₂And BiVO₄All have better crystallinity, corresponding to standard cards JCPDS No.48-0744 and No.14-0688 respectively, MoS₂/BiVO₄The peak intensity of the composite photocatalyst is reduced, but the characteristic peak still exists, which indicates that the photocatalyst is indeed MoS₂and BiVO₄The complex of (1).

Detailed Description

the invention is further illustrated by the following examples.