Preparation method and application of SnO2 / MoS2 / g-C3N4atBC composite aerogel

Abstract

The invention discloses a preparation method of SnO2 / MoS2 / g-C3N4 coated BC composite aerogel and an application of the SnO2 / MoS2 / g-C3N4 coated BC composite aerogel. G-C3N4, MoS2 and SnO are compounded, an electron structure and an electron transfer path can be changed by constructing a heterojunction, the quantum efficiency of the photocatalyst is improved, electrons are captured, compounding of the electrons and holes is inhibited, and the photocatalytic activity is improved. The degradation rate of the obtained catalyst to rhodamine B can reach 99.3% within 30 minutes. The aerogel is prepared by combining catalyst powder with SDBS, MTMS and ethanol, so that the loss of the powder is avoided, and the reusability and long-term stability of the material are ensured. After the aerogel material is recycled for five times, the degradation rate still reaches 94%, the photocatalytic degradation efficiency of the aerogel material is basically not attenuated, and the recycling performance is good.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of photocatalysts, and particularly relates to a preparation method of SnO2 / MoS2 / g-C3N4@BC composite aerogel and application thereof. BACKGROUND

[0002] With the growth of manufacturing industry, the pollutants discharged to the environment increase. Among them, the textile, printing and dyeing, leather, cosmetics, pharmaceutical, food and other industries discharge a large amount of dye wastewater, which is one of the main harmful industrial pollutants. However, in the treatment of some complex pollutants, the traditional method has limitations in efficiency and energy use, and the risk of generating secondary pollutants increases. In the process of pursuing sustainable and efficient wastewater treatment, photocatalysis has become a very promising innovative technology.

[0003] Two-dimensional inorganic semiconductor graphite carbon nitride (g-C3N4) has been widely used in the construction of new photocatalysts due to its adjustable band gap, high stability and other capabilities. However, the rapid recombination of electron-hole pairs and the weak oxidation ability of holes have always been the key factors limiting g-C3N4 photocatalysts. MoS2 has good electrical conductivity, narrow band gap and large specific surface area, but its intrinsic carrier recombination rate is high. SnO2 has important application value in photocatalytic hydrogen production, pollutant degradation and other fields due to its high electron mobility, wide band gap stability and low cost advantage. At the same time, the recycling degradation rate of powder material is very low, and the photocatalyst is in suspension, which is difficult to recycle and reuse for water purification.

[0004] Therefore, in order to solve the defects of single material, it is a technical problem to be solved in the field to develop a multi-component composite photocatalyst with high efficient charge separation and recyclable characteristics. SUMMARY

[0005] In order to solve the above problems, the application provides a SnO2 / MoS2 / g-C3N4 ternary heterojunction photocatalytic material with simple process, low cost and high photocatalytic performance, which loads the catalyst powder on the aerogel, and finally a composite aerogel with high efficiency, recyclable and repeated photocatalytic degradation of dye wastewater can be prepared.

[0006] And the obtained photocatalytic material is compounded into bacterial cellulose to construct SnO2 / MoS2 / g-C3N4@BC composite aerogel material with high efficient visible light response performance, good structural stability and recyclability. The composite aerogel material has great application potential in the field of organic dye wastewater treatment and other environmental governance.

[0007] In order to achieve the above purpose, the application adopts the following technical scheme: A preparation method of SnO2 / MoS2 / g-C3N4@BC composite aerogel, comprising the following steps: (1) Sn source is dissolved in isopropyl alcohol, and then titrated with an alkaline solution, after stirring for a certain time, aging, centrifugal washing, freeze-drying and grinding, SnO2 precursor is obtained; (2) Molybdenum disulfide is placed in isopropyl alcohol and ultrasonically treated for 1 h, and then centrifuged and dried to obtain ultrasonically exfoliated molybdenum disulfide U-MoS2; (3) The SnO2 precursor, urea, melamine and U-MoS2 are mixed and placed in an alumina crucible with a cover, and then heat-treated in a muffle furnace, after the heat treatment is completed, grinding is performed to obtain a SnO2 / MoS2 / g-C3N4 composite photocatalyst; (4) BC, SnO2 / MoS2 / g-C3N4 composite photocatalyst and SDBS are dispersed in deionized water, after uniform stirring, MTMS and anhydrous ethanol are added and uniformly stirred, and finally the mixture is freeze-dried to obtain a composite aerogel.

[0008] Further, in step (1), the Sn source is SnCl4·5H2O, the concentration in isopropyl alcohol is 37-38 mmol / L, the alkaline solution is a mixed solution of isopropyl alcohol and ammonia water, the volume ratio of isopropyl alcohol to ammonia water is 40: (10-15), and the stirring time is 20 min, and the aging time is 1 h.

[0009] Further, in step (3), the mass ratio of SnO2 precursor, urea, melamine and U-MoS2 is (0.05-0.1 g): 13.5 g: 1.5 g: (0.05-0.1 g).

[0010] Further, in step (3), the heat treatment conditions are as follows: from room temperature, the temperature is increased to 550 DEG C at a rate of 10 DEG C / min, and the temperature is kept for 2 h.

[0011] Further, in step (3), the amount ratio of BC, SnO2 / MoS2 / g-C3N4 composite photocatalyst powder, SDBS, deionized water, MTMS and anhydrous ethanol is 15 g: 0.04 g: (0.05-0.015 g): 15 g: 0.2 mL: 0.1 mL.

[0012] The application also provides the application of the SnO2 / MoS2 / g-C3N4@BC composite aerogel obtained by the above preparation method in visible light catalytic degradation of organic dye pollutants, and the organic dye pollutants are rhodamine B.

[0013] The application has the following beneficial effects: 1. The g-C3N4, MoS2 and SnO2 are compounded in the application, the formation of heterojunction can change the electronic structure and electron transfer path, improve the quantum efficiency of the photocatalyst, capture electrons, inhibit the recombination of electrons and holes, and improve the photocatalytic activity.

[0014] 2. The preparation method of the SnO2 / MoS2 / g-C3N4@BC composite aerogel is simple and convenient, the raw materials are cheap and easy to obtain, the cost is greatly reduced, and the prepared composite photocatalytic aerogel is conducive to recycling and reuse, has no pollution to the environment, realizes green chemistry.

[0015] 3. The SnO2 / MoS2 / g-C3N4@BC is used for degrading rhodamine B, the degradation rate of rhodamine B is as high as 99%, and after five degradations, the degradation rate is still 94%, the recycling performance is good, and has application prospect and practical value in the field of organic dye wastewater treatment and environmental governance. DETAILED DESCRIPTION

[0016] Figure 1 It is a SEM diagram of g-C3N4.

[0017] Figure 2 It is a SEM diagram (A) and an element distribution diagram (B) of 0.1UM-0.1Sn-CN.

[0018] Figure 3 It is an XRD diagram of g-C3N4, 0.1UM-CN and 0.1UM-0.1Sn-CN.

[0019] Figure 4 It is a steady-state photoluminescence (PL) spectrum diagram of g-C3N4, 0.1UM-CN, 0.1Sn-CN and 0.1UM-0.1Sn-CN.

[0020] Figure 5 It is a visible light catalytic degradation efficiency diagram (A) and a first-order kinetic fitting diagram (B) of g-C3N4, 0.1UM-CN, 0.1Sn-CN and 0.1UM-0.1Sn-CN on rhodamine B.

[0021] Figure 6 It is a TEM diagram of 0.1UM-0.1Sn-CN-0.01S@BC composite aerogel.

[0022] Figure 7 It is a visible light catalytic degradation efficiency diagram of 0.1UM-0.1Sn-CN@BC, 0.1UM-0.1Sn-CN-0.005S@BC, 0.1UM-0.1Sn-CN-0.01S@BC and 0.1UM-0.1Sn-CN-0.015S@BC on rhodamine B.

[0023] Figure 8 The visible light catalytic degradation cycle chart of rhodamine B by 0.1 UM-0.1 Sn-CN.

[0024] Figure 9 The visible light catalytic degradation cycle chart of rhodamine B by 0.1 UM-0.1 Sn-CN-0.01 S@BC. DETAILED DESCRIPTION

[0025] In order to make the content of the present application more convenient to understand, the technical solutions of the present application will be further described below in combination with specific embodiments, but the present application is not limited to this.

[0026] Comparative Example 1 (1) 13.5 g of urea and 1.5 g of melamine were placed in a 100 mL alumina crucible, and after covering the crucible cover, heat treatment was carried out in a muffle furnace, and under air atmosphere, the temperature was raised to 550 ℃ at a rate of 10 ℃ / min from room temperature, and then the temperature was kept for 2 h, and then the furnace was cooled to room temperature. After grinding, a light yellow g-C3N4 powder was obtained.

[0027] (2) 10 mg of g-C3N4 was weighed and added to 100 mL of rhodamine B solution with a concentration of 30 mg / L, and after ultrasonic treatment for 30 minutes in the dark, 3 mL of rhodamine B solution was taken every 5 minutes for testing the degradation rate of rhodamine B under the irradiation of a 300 W xenon lamp simulating visible light (λ ≥420 nm).

[0028] Figure 1 The SEM image of g-C3N4 can be seen, which shows that g-C3N4 presents a clear sheet-like stacking morphology, accompanied by pores and surface wrinkles, forming a loose three-dimensional porous structure.

[0029] Comparative Example 2 (1) Molybdenum disulfide (MoS2) was ultrasonically treated in isopropanol for 1 h, and the product was collected by centrifugation, and after drying in a 60 ℃ air drying oven for 2 h, ultrasonically exfoliated molybdenum disulfide (U-MoS2) was obtained.

[0030] (2) 13.5 g of urea, 1.5 g of melamine and 0.1 g of U-MoS2 were uniformly mixed and placed in a 100 mL alumina crucible, and after covering the crucible cover, heat treatment was carried out in a muffle furnace, and under air atmosphere, the temperature was raised to 550 ℃ at a rate of 10 ℃ / min from room temperature, and then the temperature was kept for 2 h, and then the furnace was cooled to room temperature. After grinding, a black MoS2 / g-C3N4 powder (0.1 UM-CN) was obtained.

[0031] Take 10 mg 0.1 UM-CN into 100 mL rhodamine B solution with a concentration of 30 mg / L, after ultrasonic treatment for 30 minutes in dark condition, use 300 W xenon lamp to simulate visible light (λ ≥420nm) irradiation, take 3 mL rhodamine B solution every 5 minutes to test the degradation rate of rhodamine B.

[0032] Comparative Example 3 (1) First, mix 20 mL isopropyl alcohol and 6.5 mL ammonia water in a 60 ℃ water bath to obtain a basic solution, then dissolve 0.521 g tin chloride pentahydrate in 40 mL isopropyl alcohol, and then add the above basic solution dropwise, keep stirring (400 r / min) for 20 min, and then let the gel stand at room temperature for 1 h. The obtained gel is washed with deionized water and centrifuged three times, and then freeze-dried to obtain a SnO2 precursor.

[0033] (2) Weigh 13.5 g urea, 1.5 g melamine and 0.1 g SnO2 precursor, mix them uniformly and put them in a 100 mL alumina crucible, cover the crucible with a lid, and then put it in a muffle furnace for heat treatment, in air atmosphere, from room temperature to 550 ℃ at a heating rate of 10 ℃ / min, and keep the temperature for 2 h, then cool the furnace to room temperature, and grind to obtain a gray SnO2 / g-C3N4 powder (0.1Sn-CN).

[0034] (3) Take 10 mg 0.1Sn-CN into 100 mL rhodamine B solution with a concentration of 30 mg / L, after ultrasonic treatment for 30 minutes in dark condition, use 300 W xenon lamp to simulate visible light (λ ≥420nm) irradiation, take 3 mL rhodamine B solution every 5 minutes to test the degradation rate of rhodamine B.

[0035] Example 1 (1) First, mix 20 mL isopropyl alcohol and 6.5 mL ammonia water in a 60 ℃ water bath to obtain a basic solution, then dissolve 0.521 g tin chloride pentahydrate in 40 mL isopropyl alcohol, and then add the above basic solution dropwise, keep stirring (400 r / min) for 20 min, and then let the gel stand at room temperature for 1 h. The obtained gel is washed with deionized water and centrifuged three times, and then freeze-dried to obtain a SnO2 precursor.

[0036] (2) Ultrasonic the molybdenum disulfide in isopropyl alcohol for 1 h, centrifuge to collect the product, and dry in a 60 ℃ air-drying oven for 2 h to obtain ultrasonic exfoliated molybdenum disulfide (U-MoS2).

[0037] (3) 13.5 g of urea, 1.5 g of melamine, 0.1 g of U-MoS2 and 0.1 g of SnO2 precursor were weighed and uniformly mixed and placed in a 100 mL alumina crucible, and after covering the crucible cover, it was placed in a muffle furnace for heat treatment, and in an air atmosphere, it was heated to 550 °C at a temperature rising rate of 10 °C / min from room temperature, and then it was kept for 2 h, and then it was cooled with the furnace, and a gray SnO2 / MoS2 / g-C3N4 powder (0.1UM-0.1Sn-CN) was obtained by grinding.

[0038] (4) 10 mg of 0.1UM-0.1Sn-CN was weighed and added to 100 mL of a rhodamine B solution with a concentration of 30 mg / L, and after ultrasonic treatment for 30 minutes in the dark, it was irradiated with a 300 W xenon lamp to simulate visible light (λ ≥420 nm), and every 5 minutes, 3 mL of the rhodamine B solution was taken to test the degradation rate of rhodamine B.

[0039] Figure 2 The SEM image and element distribution map of 0.1UM-0.1Sn-CN prepared in Example 1, the SEM can observe that the g-C3N4 sheet is closely attached to the surface and around the MoS2, which provides a basis for the construction of a heterojunction interface between the two, and helps to promote the effective separation of photo-generated electron-hole pairs, further improving the photocatalytic efficiency of the composite material. According to the element distribution, it can be seen that MoS2, SnO2 and g-C3N4 are successfully compounded.

[0040] Figure 3 The XRD patterns of g-C3N4, 0.1UM-CN and 0.1UM-0.1Sn-CN prepared in Comparative Example 1, 2 and Example 1. Two main peaks of g-C3N4 were observed at 13.1° and 27.4°, the diffraction peak at 13.1° corresponds to the (100) crystal face, indicating the periodic arrangement of the triazine unit structure in the plane, while the strong diffraction peak at 27.4° corresponds to the (002) crystal face, reflecting the layered stacking structure of g-C3N4. These diffraction characteristics are consistent with the typical g-C3N4 structure reported in the literature, indicating that the graphite phase carbon nitride material is successfully synthesized. According to the standard card comparison (PDF #77-1716), the obvious diffraction peaks of MoS2 can also be clearly observed.

[0041] Figure 4 The visible light catalytic degradation efficiency of rhodamine B of g-C3N4, 0.1UM-CN, 0.1Sn-CN and 0.1UM-0.1Sn-CN prepared in Comparative Examples 1-3 and Example 1 and the first-order kinetic fitting diagram thereof. As shown in FIG. 1, the photocatalytic degradation rate of rhodamine B of 0.1UM-0.1Sn-CN is 99.6%, which is much higher than that of g-C3N4, 0.1UM-CN and 0.1Sn-CN. Figure 4As shown, the degradation efficiency of g-C3N4 was 81.9% (Comparative Example 1) after 30 minutes of illumination, the degradation efficiency of 0.1UM-CN was 97% (Comparative Example 2), the degradation efficiency of 0.1Sn-CN was 84.4% (Comparative Example 3), and the degradation efficiency of 0.1UM-0.1Sn-CN reached 97.6% in 20 min and 99.3% after 30 min (Example 1).

[0042] First-order kinetics simulation was used to further quantitatively compare the photocatalytic activities of various photocatalysts:

[0043] k is the rate constant, t is the reaction time, C 0 is the initial concentration of RhB, C is the reaction time t is the concentration of RhB. The three curves fit well (R 2 all greater than 0.94), indicating that the degradation process conforms to the first-order kinetics model. The photocatalytic activities of all photocatalysts are arranged in the order of rate constant as follows: 0.1UM-0.1Sn-CN > 0.1UM-CN > 0.1Sn-CN > g-C3N4. The rate constant of 0.1UM-0.1Sn-CN is 0.15945 min -1 , which is 3.43 times that of pure g-C3N4 (0.04638 min -1 ), indicating that the presence of MoS2 and SnO2 inhibits the recombination of photo-generated electron / hole pairs of pure g-C3N4 and significantly promotes the photocatalytic reaction.

[0044] Figure 5 are the fluorescence spectra of g-C3N4, 0.1UM-CN, 0.1Sn-CN and 0.1UM-0.1Sn-CN prepared in Comparative Examples 1-3 and Example 1. The steady-state photoluminescence (PL) was measured under 330 nm light excitation as Figure 5The lower the fluorescence curve intensity, the lower the photoelectron / hole recombination efficiency. As shown, g-C3N4, 0.1UM-CN, 0.1Sn-CN and 0.1UM-0.1Sn-CN all show obvious emission peaks at 440 nm, which is caused by the recombination of photo-generated electron-hole pairs. The sample g-C3N4 shows the highest fluorescence intensity, indicating that the pure g-C3N4 electron-hole pair recombination rate is very fast. The addition of MoS2, SnO2 causes the weakening of photo-generated electron-hole recombination. Further introduction into ternary composite material, 0.1UM-0.1Sn-CN PL peak intensity decreases and 0.1UM-0.1Sn-CN is the lowest among all samples, indicating that it has the fastest charge separation efficiency.

[0045] Example 2 Take 15 g BC and 40 mg 0.1UM-0.1Sn-CN catalyst powder in 15 g deionized water, stir vigorously (400 r / min) for 1 h, make sure the mixture is uniform. Then add 0.2 mL MTMS (methyltrimethoxysilane), 0.1 mL anhydrous ethanol, continue to stir (400 r / min) for 1 h, then pour the mixture into a circular mold (diameter 60 mm petri dish) first at -20℃ freeze for 24 h, after 48 h freeze drying to get 0.1UM-0.1Sn-CN@BC composite aerogel.

[0046] Example 3 Take 15 g BC, 40 mg 0.1UM-0.1Sn-CN catalyst powder and 0.005 g SDBS (sodium dodecyl benzene sulfonate) dispersed in 15 g deionized water, stir vigorously (400 r / min) for 1 h, make sure the mixture is uniform. Then add 0.2 mL MTMS, 0.1 mL anhydrous ethanol, continue to stir (400 r / min) for 1 h, then pour the mixture into a circular mold (diameter 60 mm petri dish) first at -20℃ freeze for 24 h, after 48 h freeze drying to get 0.1UM-0.1Sn-CN-0.005S@BC composite aerogel.

[0047] Example 4 Take 15 g BC, 40 mg 0.1UM-0.1Sn-CN catalyst powder and 0.01 g SDBS dispersed in 15 g deionized water, stir vigorously (400 r / min) for 1 h, make sure the mixture is uniform. Then add 0.2 mL MTMS, 0.1 mL anhydrous ethanol, continue to stir (400 r / min) for 1 h, then pour the mixture into a circular mold (diameter 60 mm petri dish) first at -20℃ freeze for 24 h, after 48 h freeze drying to get 0.1UM-0.1Sn-CN-0.01S@BC composite aerogel.

[0048] Figure 6 TEM image of the prepared 0.1UM-0.1Sn-CN-0.01S@BC composite aerogel. The surface of the single catalytic cluster is loose and porous, and the three-dimensional nanofiber network formed by the bacterial cellulose can be clearly observed, which provides a good support platform for the loading and dispersion of the catalyst.

[0049] Example 5 15 g of BC, 40 mg of 0.1UM-0.1Sn-CN catalyst powder, and 0.015 g of SDBS were weighed into 15 g of deionized water and stirred vigorously (400 r / min) for 1 h to ensure uniform mixing. Then 0.2 mL of MTMS and 0.1 mL of anhydrous ethanol were added, and stirring (400 r / min) was continued for 1 h. The mixture was then poured into a circular mold (diameter 60 mm petri dish) and frozen at -20°C for 24 h. After 48 h of freeze-drying, 0.1UM-0.1Sn-CN-0.015S@BC composite aerogel was obtained.

[0050] Figure 7 Visible light catalytic degradation efficiency of rhodamine B by 0.1UM-0.1Sn-CN@BC, 0.1UM-0.1Sn-CN-0.005S@BC, 0.1UM-0.1Sn-CN-0.01S@BC, and 0.1UM-0.1Sn-CN-0.015S@BC prepared in Examples 3-5, the specific steps are the same as those in step (4) of Example 1. With the increase of the amount of SDBS added, the photocatalytic performance first increases and then decreases. 0.1UM-0.1Sn-CN-0.01S@BC shows the best photocatalytic effect.

[0051] Comparative Example 4 40 mg of 0.1UM-0.1Sn-CN was weighed into 100 mL of rhodamine B solution with a concentration of 30 mg / L, and after ultrasonic treatment for 30 min in the dark, it was irradiated with a 300 W xenon lamp to simulate visible light (λ ≥420 nm) for 60 min. After the reaction was completed, the catalyst powder was separated by centrifugation at 7000 r / min for 5 min, washed with deionized water twice, and dried in a vacuum drying oven at 60°C for 4 h. The recovered 0.1UM-0.1Sn-CN was used for the next catalytic cycle, and the results are shown in Figure 8 As shown in the table, the initial mass of 40 mg was reduced to 4.5 mg after three cycles, and the degradation rate was only 45.2% in the fourth cycle.

[0052] Example 6 The aerogel 0.1 UM-0.1 Sn-CN-0.01 S@BC was taken out of the dye solution and gently squeezed to remove the adsorbed residual liquid until no water droplets were squeezed out. At this time, the morphology of the aerogel remained unchanged, and no drying treatment was required. The aerogel was directly placed in a freshly prepared dye solution (100 mL of a 30 mg / L rhodamine B solution) to carry out the next round of photocatalytic experiments. The results of the cycle are shown in Figure 9 As shown, the degradation rate still reached 94% after five cycles.

[0053] Obviously, the above examples are only examples for the sake of clarity, and are not limitations on the embodiments. Based on the above description, those of ordinary skill in the art can also make other different forms of changes or variations. Here, all the embodiments cannot be exhausted. The changes or variations that are not inferred are still within the protection scope of the present application.

Claims

1. A method for preparing SnO2 / MoS2 / g-C3N4@BC composite aerogel, characterized in that: Comprise the following steps: (1) Sn source is dissolved in isopropanol, and then titrated with an alkaline solution. After stirring for a certain period of time, SnO2 precursor is obtained through aging, centrifugal washing, freeze-drying and grinding; (2) Molybdenum disulfide is placed in isopropanol and ultrasonically treated for 1 h. After centrifugal washing and drying, ultrasonically exfoliated molybdenum disulfide U-MoS2 is obtained; (3) SnO2 precursor, urea, melamine and U-MoS2 are mixed and placed in an alumina crucible with a cover, and then heat-treated in a muffle furnace. After the heat treatment, SnO2 / MoS2 / g-C3N4 composite photocatalyst is obtained through grinding; (4) BC, SnO2 / MoS2 / g-C3N4 composite photocatalyst and SDBS are dispersed in deionized water. After uniform stirring and dispersion, MTMS and anhydrous ethanol are added and uniformly stirred. The obtained mixture is freeze-dried to obtain composite aerogel.

2. The method of claim 1, wherein: In step (1), the Sn source is SnCl4·5H2O, and the concentration in isopropanol is 37-38 mmol / L; the alkaline solution is a mixed solution of isopropanol and ammonia water, wherein the volume ratio of isopropanol to ammonia water is 40: (10-15), and the stirring time is 20 min, and the aging time is 1 h.

3. The method of claim 1, wherein: In step (3), the mass ratio of SnO2 precursor, urea, melamine and U-MoS2 is (0.05-0.1 g): 13.5 g: 1.5 g: (0.05-0.1 g).

4. The method of claim 1, wherein: In step (3), the heat treatment conditions are as follows: the temperature is increased to 550 ℃ at a rate of 10 ℃ / min from room temperature, and the temperature is kept for 2 h.

5. The method of claim 1, wherein: In step (3), the amount ratio of BC, SnO2 / MoS2 / g-C3N4 composite photocatalyst powder, SDBS, deionized water, MTMS and anhydrous ethanol is 15 g: 0.04 g: (0.05-0.015 g): 15 g: 0.2 mL: 0.1 mL.

6. SnO2 / MoS2 / g-C3N4@BC composite aerogel prepared by the preparation method of any one of claims 1-5.

7. Application of the SnO2 / MoS2 / g-C3N4@BC composite aerogel of claim 6 in visible light catalytic degradation of organic dye pollutants.

8. Use according to claim 7, characterized in that: The organic dye pollutants are rhodamine B.

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