A controllable flower-like BSOCB photocatalyst with nanosheet layer stacking and a preparation method thereof
By combining CTAB and CTAC, a controllable flower-like BSOCB photocatalyst with stacked nanosheets was prepared, which solved the problem of insufficient surface area and active sites in bismuth-based photocatalytic materials, and achieved high-efficiency photocatalytic performance and broad application potential.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHAANXI UNIV OF SCI & TECH
- Filing Date
- 2023-09-19
- Publication Date
- 2026-06-09
AI Technical Summary
Existing bismuth-based photocatalytic materials have limited surface area and active sites, making it difficult to simultaneously achieve excellent light absorption capacity and efficient separation and migration of photogenerated carriers.
By employing the combined action of CTAB and CTAC, a controllable flower-like BSOCB photocatalyst with stacked nanosheets was prepared. By constructing a heterogeneous photocatalyst with controllable band gap and morphology, the surface area and active sites were increased, the hydrophilic and oleophilic properties of the catalyst were improved, and the photocatalytic efficiency was enhanced.
It significantly improves the light utilization rate and photocatalytic activity of photocatalysts, enhances the degradation ability of different pollutants, broadens the application range, and has universal applicability and recyclability.
Smart Images
Figure CN117085744B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of photocatalyst technology, and specifically relates to a controllable flower-like BSOCB photocatalyst with nanosheet stacking and its preparation method. Background Technology
[0002] Photocatalysis technology can effectively solve wastewater treatment problems in environmental pollution, and it is also a technology for developing and utilizing solar energy. Bismuth-based semiconductors generally have good photocatalytic performance. Their suitable bandgap and special layered structure give them a wide visible light response range and good physical and chemical stability, making them a major research hotspot in the field of photocatalysis.
[0003] Currently, the surface area and active sites of bismuth-based photocatalysts are limited, making it difficult to simultaneously achieve excellent light absorption and high photogenerated carrier separation and migration efficiency. By incorporating surfactants into bismuth silicate photocatalysts, on the one hand, the synergistic effect of surfactants CTAC and CTAB can be leveraged to construct heterogeneous photocatalysts with controllable band gaps and morphologies, resulting in high-performance, controllable flower-like BSOCB photocatalysts. This increases the surface area and the number of active sites, thereby enhancing the photocatalytic effect. On the other hand, it significantly improves the surface hydrophilic and oleophilic properties of the heterogeneous material, improving the compatibility between the catalytic material and organic dyes and antibiotics, thus increasing catalytic efficiency. Summary of the Invention
[0004] To overcome the shortcomings of existing technologies, the present invention aims to provide a controllable flower-like BSOCB photocatalyst with nanosheet stacking and its preparation method, utilizing the combined effect of CTAB and CTAC. This method is simple in process and equipment requirements, yields materials with good dispersibility, and produces composite photocatalysts with uniform particle size distribution, smaller and thinner sheet-like structures, and more active sites. This structure can effectively improve light utilization and enhance photocatalytic activity.
[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:
[0006] A method for preparing a controllable flower-like BSOCB photocatalyst composed of stacked nanosheets includes the following steps:
[0007] Step 1: Add complexing agent, bismuth nitrate and tetraethyl orthosilicate to a mixed solvent of deionized water and anhydrous ethanol and react for 1 h to 3 h. Then add dispersant until completely dissolved to obtain precursor solution.
[0008] Step 2: Evaporate and dry the precursor solution to obtain a dry gel, heat the dry gel at 500℃~1000℃ for 2h~8h, and grind it to obtain a BSO heterogeneous photocatalyst.
[0009] Step 3: Add 0.1g to 0.5g of the BSO heterogeneous photocatalyst to water and stir to form a suspension, and adjust the pH to 1 to 2;
[0010] Step 4: Prepare CTAC and CTAB solutions with a concentration of 10 g / L to 20 g / L respectively. Mix the two solutions at a volume ratio of 1:1 to 4:1 to prepare CTAX solution. Add 5 mL to 8 mL of CTAX solution to the suspension, stir, centrifuge and dry to obtain controllable flower-like BSOCB photocatalyst with nanosheet stacking.
[0011] In one embodiment, in step 1, the volume ratio of deionized water to anhydrous ethanol in the mixed solvent is 4:7.
[0012] In one embodiment, in step 1, the complexing agent is citric acid; the dispersant is citric acid and / or polyethylene glycol, wherein the polyethylene glycol is polyethylene glycol 400 and / or polyethylene glycol 6000, and when the dispersant is a mixture, the ratio is arbitrary.
[0013] In one embodiment, the amount of the complexing agent is 0.05 mol to 0.10 mol, the amount of the mixed solvent is 5 mL to 15 mL, the amount of bismuth nitrate is 0.005 mol to 0.010 mol, the amount of tetraethyl orthosilicate is based on a molar ratio of Bi:Si = 6:1, and the amount of the dispersant is 1 g to 5 g.
[0014] In one embodiment, in step 2, the precursor solution is stirred and evaporated in a water bath at 50°C to 100°C until it becomes a gel. The gel is then dried at 100°C to 200°C for 5 to 10 hours until it becomes a dry gel. The resulting dry gel is then placed in a muffle furnace for heat treatment and then ground to obtain the BSO heterogeneous photocatalyst.
[0015] In one embodiment, step 3 involves adding 0.1g to 0.5g of bismuth silicate powder to 20mL to 50mL of deionized water, stirring to form a suspension, adding 100μL to 500μL of nitric acid to adjust the pH to 1 to 2, and acidifying for 20min to 30min.
[0016] In one embodiment, in step 4, as the CTAC content gradually increases, the resulting BSOCB exhibits a flower shape with perpendicular intersections between slices.
[0017] The present invention also claims protection for a controllable flower-shaped BSOCB photocatalyst prepared by the aforementioned preparation method, which can be used as a catalyst for purifying chemical wastewater.
[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0019] 1. By effectively utilizing the combined effects of CTAX, CTAX can promote the occurrence of early reactions, enabling Bi... 3+ and Si 4+ The bismuth silicate powder can be uniformly distributed into the network structure, providing favorable conditions for the heat treatment process and forming a bismuth silicate powder with good crystallinity. Simultaneously, during the reaction, CTAC, as a size dispersant, significantly reduces the particle size of the powder flakes, making the sharp edges rounded and the particles densely packed together with a smoother surface. CTAB, as a morphological dispersant, enables the photocatalyst to grow nanosheets outward from the original ellipsoidal bismuth silicate morphology, gradually increasing the amount of BiOCl growing along the (110) direction. The resulting BSOCB exhibits a flower-like shape with perpendicular intersections between the flakes. Furthermore, the addition of CTAB and CTAC induces new crystal orientations in the sample, promoting multidimensional growth of the catalyst. Since the bismuth silicate powder is composed of nanoscale units, this effectively increases the surface area and active sites of the bismuth silicate photocatalyst, enhancing its photocatalytic effect on different pollutants.
[0020] 2. By effectively utilizing the halide ions introduced during the reaction process by CTAX, [SiO3] in Bi2O2SiO3 can be better converted under acidic conditions. 2- It transforms into [Bi2O2] 2+ To promote the formation of BiOX, the increase of Bi2O2SiO3 phase undoubtedly provides a basis for more transformations. More BiOX and BSO form heterostructures, inducing BiOX to form double heterojunctions. In this process, lattice distortion will cause oxygen vacancies. Due to the presence of oxygen vacancies, the capture ability of electron-hole pairs is greatly enhanced, thereby greatly improving the separation efficiency of photogenerated electron-hole pairs. Furthermore, due to the surfactant properties of CTAX itself and the chemical adsorption of pollutants, the reactants only need to overcome a very small activation energy to activate the catalytic reaction, which accelerates the photocatalytic efficiency to a certain extent.
[0021] 3. Due to electrostatic adsorption leading to surface passivation, CTAX selectively adheres to the BSO surface and preferentially grows in a directional manner. Surfactants can effectively improve the compatibility of BSO heteromaterials, thereby enhancing catalytic performance. Furthermore, due to the different formulation ratios of the BSO series photocatalysts, the generated BiOCl... x Br 1-x The band position can be adjusted between BiOCl and BiOBr, which can be adjusted for different organic compounds, thereby improving the degradation efficiency of different organic compounds.
[0022] 4. The preparation process of this invention is simple, the prepared powder has a uniform particle size distribution and light agglomeration, and the heterojunction interface and layered structure have a synergistic effect to enhance the photocatalytic activity. The prepared BSOCB series photocatalysts also have universal applicability and recyclability for antibiotics, which greatly broadens their application scope and application prospects. Attached Figure Description
[0023] Figure 1 This is a SEM image of a controllable flower-like BSOCB photocatalyst with stacked nanosheets.
[0024] Figure 2 The photocatalytic degradation curve of Rhodamine B is shown by a controllable flower-like BSOCB photocatalyst with nanosheet stacking. Detailed Implementation
[0025] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings and examples. The technical solutions of the present invention are not limited to the specific embodiments listed below, but also include any combination of the specific methods.
[0026] A method for preparing BSOCB photocatalysts via ion exchange composite of CTAB and CTAC. The method for preparing the controllable flower-like heterogeneous composite photocatalyst includes the following steps:
[0027] Step 1: Using citric acid as a complexing agent and polyethylene glycol as a dispersant, deionized water and anhydrous ethanol are mixed in a volume ratio of 4:7 to prepare a 5mL-15mL mixed solvent. 0.05mol-0.10mol of citric acid is weighed and added to the mixed solution. After complete dissolution, 0.005mol-0.010mol of bismuth nitrate is added. Then, tetraethyl orthosilicate is added at a ratio of nBi:nSi = 6:1 and reacted for 1h-3h. Finally, 1g-5g of polyethylene glycol is added until completely dissolved to obtain the precursor solution.
[0028] In this step, the dispersant is one or more of citric acid, polyethylene glycol 400, and polyethylene glycol 6000. When there are multiple dispersants, the ratio is arbitrary.
[0029] Step 2: The precursor solution is then stirred and evaporated in a water bath at 50℃ to 100℃ until it becomes a gel. The gel is then dried at 100℃ to 200℃ for 5h to 10h until it becomes a dry gel. The dry gel is then placed in a muffle furnace and heat-treated at 500℃ to 1000℃ for 2h to 8h before being ground to obtain the BSO heterogeneous photocatalyst.
[0030] Step 3: Add 0.1g to 0.5g of bismuth silicate powder to 20mL to 50mL of deionized water, stir to form a suspension, add 100μL to 500μL of 68% nitric acid solution to adjust the pH to 1 to 2, and acidify for 20min to 30min.
[0031] Step 4: Prepare CTAC and CTAB solutions with concentrations of 10 g / L to 20 g / L, and mix them at a ratio of V(CTAC):V(CTAB) of 1:1 to 4:1 to prepare a CTAX solution. Finally, add 5 mL to 8 mL of the resulting CTAX solution to the sample, stir, centrifuge, and dry to obtain the BSOCB photocatalytic material.
[0032] This step modifies and regulates the growth of bismuth silicate (BSO) by introducing hexadecyltrimethylammonium bromide (CTAB) and hexadecyltrimethylammonium chloride (CTAC), constructing a heterogeneous photocatalyst with controllable band gap and morphology. The addition of CTAC reduces the particle size of the sheet-like powder and decreases its packing density, while the addition of CTAB promotes the formation of a flower-like structure in the product. The combined effect of these two dispersants modifies BSO, controlling the formation of the heterogeneous structure and resulting in a controllable flower-like structure with thin sheet-like packing. This effectively increases the surface area while significantly improving the absorption rate of visible light radiation.
[0033] In this invention, CTAC and CTAB have different effects on the BSO heterogeneous photocatalyst, and different amounts lead to different product morphologies and properties. To further explore the effect of composite CTAX on the morphology of BSOCB, analysis using SEM and photocatalytic performance diagrams revealed that when the CTAC content in the CTAX solution is low, it is difficult to induce BiOX formation, causing the BSOCB nanosheets to continue stacking in one direction, resulting in a thicker morphology. However, as the CTAC content gradually increases, the resulting BSOCB exhibits a flower-like shape with perpendicular intersections between the nanosheets. For the BSOCB photocatalyst, CTAX provides more crystal orientations, allowing more contaminants to react at the active sites, thereby effectively improving the photocatalytic effect.
[0034] This invention also claims protection for a method for preparing a controllable flower-shaped BSOCB photocatalyst using a method for preparing nanosheet stacked BSOCB photocatalysts.
[0035] Industrial production processes may generate a lot of industrial wastewater, which contains many organic dyes and, in some cases, antibiotic residues. Adding the photocatalyst prepared under the conditions of this invention to industrial wastewater can degrade these pollutants, reducing environmental pollution. Therefore, the controllable flower-like BSOCB photocatalyst with stacked nanosheets prepared in this invention can be used as a catalyst for purifying chemical wastewater.
[0036] Example 1
[0037] (1) Using citric acid as a complexing agent and polyethylene glycol as a dispersant, 10 mL of mixed solvent was prepared by mixing deionized water and anhydrous ethanol in a volume ratio of 4:7. 0.07 mol of citric acid was weighed and added to the mixed solution. After complete dissolution, 0.005 mol of bismuth nitrate was added. Tetraethyl orthosilicate was then added at a ratio of nBi:nSi = 6:1 and reacted for 1 h. Finally, 3 g of polyethylene glycol was added until complete dissolution was achieved to obtain the precursor solution.
[0038] (2) The precursor solution was then stirred and evaporated in an 80°C water bath until it became gel-like. The gel was then dried at 120°C for 7 hours to obtain a dry gel. The dry gel was then placed in a muffle furnace and heat-treated at 600°C for 4 hours before being ground to obtain the BSO heterogeneous photocatalyst.
[0039] (3) Add 0.2g of bismuth silicate powder to 20mL of deionized water, stir to form a suspension, add 200μL of nitric acid to adjust the pH to 1, and acidify for 20min.
[0040] (4) Prepare CTAC and CTAB solutions with a concentration of 10 g / L, and mix them at a ratio of V(CTAC):V(CTAB) of 1:1 to prepare CTAX solution. Finally, add 5 mL of the resulting CTAX solution to the sample, stir, centrifuge and dry to obtain BSOCB photocatalytic material.
[0041] Example 2
[0042] (1) Using citric acid as a complexing agent and polyethylene glycol as a dispersant, 20 mL of mixed solvent was prepared by mixing deionized water and anhydrous ethanol in a volume ratio of 4:7. 0.09 mol of citric acid was weighed and added to the mixed solution. After complete dissolution, 0.008 mol of bismuth nitrate was added. Tetraethyl orthosilicate was added at a ratio of nBi:nSi = 6:1 and reacted for 2 h. Finally, 4 g of polyethylene glycol was added until complete dissolution was achieved to obtain the precursor solution.
[0043] (2) The precursor solution was then stirred and evaporated in a 90°C water bath until it became gel-like. The gel was dried at 150°C for 5 hours to obtain a dry gel. The dry gel was then placed in a muffle furnace and heat-treated at 630°C for 5 hours before being ground to obtain the BSO heterogeneous photocatalyst.
[0044] (3) Add 0.26g of bismuth silicate powder to 30mL of deionized water, stir to form a suspension, add 400μL of nitric acid to adjust the pH to 1, and acidify for 20min.
[0045] (4) Prepare CTAC and CTAB solutions with a concentration of 10 g / L, and mix them at a ratio of V(CTAC):V(CTAB) of 2:1 to prepare CTAX solution. Finally, add 5 mL of the resulting CTAX solution to the sample, stir, centrifuge and dry to obtain BSOCB photocatalytic material.
[0046] The SEM image of the product obtained in this embodiment is shown below. Figure 1 As shown, the powder particles are stacked together in a thin, sheet-like structure with a thickness of approximately 0.05 μm and a relatively smooth surface. The nanosheets grow outwards, and the sheets stack together to form a flower-like structure. The morphology is not destroyed under high-temperature conditions (heat treatment in the muffle furnace in step 2), and this structure provides more active sites, which can improve its photocatalytic performance.
[0047] Figure 2 The image shows the photocatalytic degradation curve of the catalyst obtained in this embodiment in a solution containing Rhodamine B organic dye. In the experiment, 30 mL of Rhodamine B (concentration 10 mg / L) was used, and 3 mg of catalyst was added. After addition, the photocatalytic reaction was carried out for 90 minutes, including 60 minutes of dark reaction and 30 minutes of light reaction. It can be seen that under 30 minutes of light irradiation, the degradation rate was almost 100%. Combined with the SEM image, this is attributed to the fact that CTAX provides more crystal plane orientations, allowing more pollutants to react at the active sites, thereby effectively improving the photocatalytic effect.
[0048] The method of this invention is simple to operate, and the prepared powder has a uniform particle size distribution and good dispersibility. The resulting composite material not only has the effect of a new heterostructure, but the smaller and thinner lamellar structure also provides more active sites. The photocatalytic degradation rate reaches 98.1% after 150 min of light irradiation, showing higher photocatalytic performance. In addition, the photocatalyst has universal applicability and recyclability for antibiotics, and has the ability to degrade tetracycline (TC), norfloxacin (NFX) and ciprofloxacin (CIP), which greatly broadens its application scope and application prospects.
[0049] In further embodiments of the present invention, different combinations of the aforementioned parameters were used. For example, in step 1), the mixed solvent was selected as 5 mL, 10 mL, and 15 mL, the citric acid was selected as 0.05 mol, 0.08 mol, and 0.10 mol, and the bismuth nitrate was selected as 0.005 mol, 0.008 mol, and 0.01 mol. Polyethylene glycol was selected as 1 g, 3 g, and 5 g in combination; the reaction time was selected as 1 h, 2 h, and 3 h. The results showed that precursor solutions could be prepared in all these cases.
[0050] Similarly, in step 2), the water bath temperatures were selected as 50℃, 80℃, and 100℃, the drying temperatures as 100℃, 150℃, and 200℃, the drying times as 5h, 8h, and 10h, the heat treatment temperatures as 500℃, 800℃, and 1000℃, and the heat treatment times as 2h, 4h, and 8h were combined; the results show that BSO heterogeneous photocatalysts can be prepared in all of these combinations.
[0051] Similarly, in step 3), the amounts of bismuth silicate powder were 0.1g, 0.3g, and 0.5g; the amounts of deionized water were 20mL, 35mL, and 50mL; the amounts of nitric acid solution were 100μL, 300μL, and 500μL; the amounts of pH were 1, 1.5, and 2; and the amounts of acidification time were 20min, 25min, and 30min. The results demonstrate that BSOCB photocatalyst materials can be prepared using all of these methods.
[0052] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, substitutions, combinations, simplifications, etc. made based on the principles or spirit of the present invention should be considered equivalent substitutions and are included within the protection scope of the present invention.
Claims
1. A method for preparing a controllable flower-like BSOCB photocatalyst composed of stacked nanosheets, characterized in that, Includes the following steps: Step 1: Add a complexing agent, bismuth nitrate, and tetraethyl orthosilicate to a mixed solvent of deionized water and anhydrous ethanol and react for 1 h to 3 h. Then add a dispersant until completely dissolved to obtain a precursor solution. The amount of the complexing agent is 0.05 mol to 0.10 mol, the amount of the mixed solvent is 5 mL to 15 mL, the amount of bismuth nitrate is 0.005 mol to 0.010 mol, the amount of tetraethyl orthosilicate is based on a molar ratio of Bi:Si = 6:1, and the amount of dispersant is 1 g to 5 g. Step 2: Evaporate and dry the precursor solution to obtain a dry gel, heat the dry gel at 500℃~1000℃ for 2h~8h, and grind it to obtain a BSO heterogeneous photocatalyst. Step 3: Add 0.1 g to 0.5 g of the BSO heterogeneous photocatalyst to water and stir to form a suspension, and adjust the pH to 1 to 2; Step 4: Prepare CTAC and CTAB solutions with a concentration of 10 g / L to 20 g / L. Mix them at a volume ratio of 1:1 to 4:1 to prepare CTAX solution. Add 5 mL to 8 mL of CTAX solution to the suspension, stir, centrifuge and dry to obtain controllable flower-shaped BSOCB photocatalyst with nanosheet stacking. As the CTAC content gradually increases, the obtained BSOCB exhibits a flower shape with perpendicular intersections between the slices.
2. The method for preparing the controllable flower-like BSOCB photocatalyst with nanosheet stacking according to claim 1, characterized in that, In step 1, the volume ratio of deionized water to anhydrous ethanol in the mixed solvent is 4:
7.
3. The method for preparing the controllable flower-like BSOCB photocatalyst with nanosheet stacking according to claim 1, characterized in that, In step 1, the complexing agent is citric acid; the dispersant is citric acid and / or polyethylene glycol, wherein the polyethylene glycol is polyethylene glycol 400 and / or polyethylene glycol 6000, and when the dispersant is a mixture, the ratio is arbitrary.
4. The method for preparing the controllable flower-like BSOCB photocatalyst with nanosheet stacking according to claim 1, characterized in that, In step 2, the precursor solution is stirred and evaporated in a water bath at 50℃ to 100℃ until it becomes a gel. The gel is then dried at 100℃ to 200℃ for 5 h to 10 h until it becomes a dry gel. The resulting dry gel is then placed in a muffle furnace for heat treatment and then ground to obtain the BSO heterogeneous photocatalyst.
5. The method for preparing the controllable flower-like BSOCB photocatalyst with nanosheet stacking according to claim 1, characterized in that, In step 3, 0.1 g to 0.5 g of bismuth silicate powder is added to 20 mL to 50 mL of deionized water, stirred to form a suspension, and 100 μL to 500 μL of nitric acid is added to adjust the pH to 1 to 2, and acidified for 20 min to 30 min.
6. A controllable flower-like BSOCB photocatalyst with nanosheet stacking prepared by the preparation method described in any one of claims 1 to 5.
7. The application of the controllable flower-shaped BSOCB photocatalyst of nanosheet stacking as described in claim 6 as a catalyst for purifying chemical wastewater.