Quantum dot / bismuth oxyhalide composite material, and preparation method and application thereof
Quantum dot/bismuth halide composite powders were prepared by oil bath heating and liquid phase exfoliation methods, which solved the problem of uncontrollable morphology at high temperatures and enabled the industrial production of low-temperature, high-efficiency nanosheet powders and improved photocatalytic performance, especially in the effective degradation of organic matter under dark conditions.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-06-25
- Publication Date
- 2026-03-03
AI Technical Summary
Existing quantum dot/bismuth halide composite catalysts require high preparation temperatures and have poor morphology controllability, making industrial-scale production difficult. Furthermore, the photogenerated electron-hole pair recombination rate is fast, resulting in limited light absorption capacity.
Bismuth halide catalyst powder was prepared by oil bath heating, and quantum dots such as molybdenum disulfide, black phosphorus or titanium carbide were deposited on its surface by liquid phase exfoliation to form a nanosheet structure. Mechanical energy was introduced by ultrasound to construct a photogenerated electron transfer pathway.
The method enables the low-temperature preparation of highly uniform nanosheet composite powders, which improves the separation and migration time of photogenerated carriers, broadens the application range of photocatalysis, and enhances photocatalytic performance, especially in the case of dark conditions, it can effectively catalyze degradation.
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Figure CN116870936B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of composite catalysts, specifically relating to a quantum dot / bismuth halide composite material, its preparation method, and its application. Background Technology
[0002] Bismuth oxyhalides have great potential in the field of piezoelectric-photocatalysis, but their practical application is severely hampered by problems such as the fast recombination rate of photogenerated electron-hole pairs, limited visible light absorption, and small specific surface area. Quantum dots, with their high conductivity and small size, theoretically can effectively overcome the limitations of single bismuth-based semiconductors.
[0003] However, current reports on this type of composite catalyst powder are mainly focused on preparation by hydrothermal or solvothermal methods. The main drawbacks are the high reaction temperature and poor morphology controllability, which leads to a reduction in active sites and a decrease in photocatalytic performance, while making it difficult to achieve industrial production. Summary of the Invention
[0004] The purpose of this invention is to overcome the above-mentioned technical deficiencies and provide a quantum dot / bismuth halide composite material, its preparation method and application, thereby solving the technical problems of high preparation temperature and poor morphology controllability of quantum dot / bismuth halide composite catalysts in the prior art.
[0005] To achieve the above-mentioned technical objectives, the present invention provides a quantum dot / bismuth halide composite powder:
[0006] It includes a sheet-like bismuth halide matrix and quantum dot particles deposited on the surface of the bismuth halide matrix, with two or more quantum dot particles deposited on the surface of each bismuth halide matrix; the quantum dots are one or more of molybdenum disulfide quantum dots, black phosphorus quantum dots and titanium carbide quantum dots.
[0007] Furthermore, the length and width of the bismuth halide are both 50–300 nanometers, and the size of the quantum dot particles is 2–50 nanometers.
[0008] Furthermore, the bismuth halide is one or more of bismuth iodide, bismuth bromooxy and bismuth chloride.
[0009] The preparation method of the quantum dot / bismuth halide composite powder as described above includes the following steps:
[0010] (1) Take bismuth oxyiodide and halide as the main materials, add the first solvent and mix them. Prepare bismuth oxyhalide suspension by oil bath method, and control the oil bath temperature at 60-80℃. Then centrifuge, dry and grind the bismuth oxyhalide suspension to obtain bismuth oxyhalide powder.
[0011] Quantum dot raw materials and a second solvent are mixed, and a quantum dot solution is obtained by liquid phase exfoliation under ultrasonic conditions.
[0012] (2) Mix bismuth halide powder and quantum dot solution, heat in a water bath to combine quantum dots and bismuth halide, and then perform post-processing to obtain quantum dot / bismuth halide composite powder.
[0013] Further, in step (1), the halide is one or more of bismuth oxyiodide, bismuth oxybromide and bismuth oxychloride; the molar ratio of bismuth oxyiodide to halide is 1:1;
[0014] The first solvent is a mixed solution of ethylene glycol and deionized water; the molar volume ratio of the main material to the first solvent is 4 mmol: (30-50) ml;
[0015] The oil bath heating time is 2 to 3 hours.
[0016] Further, in step (1), the second solvent is N-methylpyrrolidone, ethanol solution or ammonia solution; the quantum dot raw material is ground and then mixed with the second solvent, and the mass ratio of the quantum dot raw material to the second solvent is (0.01~0.2):10.
[0017] Furthermore, in step (1), the power of the ultrasonic condition is 120-150W, and the liquid phase ablation method is ultrasonic ablation under an ice bath for 60-300 minutes.
[0018] Furthermore, in step (2), quantum dots account for 0.02 to 2% of the total weight of the bismuth halide powder.
[0019] Furthermore, in step (2), the water bath heating is carried out at 40-80°C for 2-4 hours.
[0020] The above quantum dot / bismuth halide composite powder is used as a piezoelectric-photocatalyst.
[0021] Compared with the prior art, the beneficial effects of the present invention include:
[0022] 1. This invention uses an oil bath heating method to prepare bismuth halide catalyst powder, which has a highly uniform nanosheet morphology. The lower reaction temperature is beneficial for large-scale industrial production.
[0023] 2. This invention uses a combination of quantum dots and bismuth oxyhalide to construct a photogenerated electron transfer pathway, which can greatly improve the separation and migration time of photogenerated carriers and promote the improvement of photocatalytic degradation efficiency.
[0024] 3. This invention introduces mechanical energy through ultrasound, achieving the organic unity of light energy and mechanical energy. Mechanical energy, as an important driving force, can further promote the efficient catalytic reaction.
[0025] 4. This invention broadens the application scope of photocatalysts, enabling partial catalytic degradation to be completed even under dark conditions, thus possessing strong practical value.
[0026] 5. The research mechanism of this invention is to enhance the internal built-in electric field by using external driving force (mechanical energy), thereby improving the separation efficiency of photogenerated carriers and holes. That is, it enhances its photocatalytic performance through the piezoelectric effect, and the performance is greatly improved compared with single photocatalysis. Attached Figure Description
[0027] Figure 1 This is an HRTEM image of the titanium carbide quantum dot / bismuth oxybromide composite powder prepared in Example 1 of the present invention.
[0028] Figure 2 The images show the XRD patterns of the titanium carbide quantum dot / bismuth oxybromide composite powder prepared in Example 1 of this invention before and after use.
[0029] Figure 3 The image shows the EDX spectrum of the titanium carbide quantum dot / bismuth oxybromide composite powder prepared in Example 1 of this invention.
[0030] Figure 4 The fluorescence spectra of the titanium carbide quantum dot / bismuth oxybromide composite powders prepared in Examples 1, 10 and 11 of this invention are shown.
[0031] Figure 5 The images show the morphology of BiOBr at different temperatures, where (a) is at low temperature and (b) is at high temperature.
[0032] Figure 6 Degradation curves (MV, 20 mg / L, 50 ml) under different conditions (a) visible light, b) ultrasonic vibration, c) visible light and ultrasonic vibration. Detailed Implementation
[0033] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.
[0034] This invention provides a method for preparing a quantum dot / bismuth halide composite material, comprising the following steps:
[0035] S1. Take bismuth oxyiodide and halide as the main materials, add them to the first solvent and mix. Heat the mixture in an oil bath at 60-80℃ for 2-3 hours to obtain a bismuth oxyhalide suspension. Then centrifuge, dry and grind the suspension to obtain bismuth oxyhalide powder. The inorganic phase material used in the bismuth oxyhalide is one or more of bismuth oxyiodide, bismuth oxybromide and bismuth oxychloride.
[0036] S2. Extract quantum dot solutions from the bulk material using a liquid phase exfoliation method. The extracted quantum dot solutions are one or more of molybdenum disulfide quantum dots, black phosphorus quantum dots, and titanium carbide quantum dots.
[0037] S3. The bismuth halide powder and the quantum dot solution are mixed, and the quantum dots account for 0.02 to 2% of the total weight of the bismuth halide powder after the composite is formed.
[0038] S4. The modified piezoelectric-photocatalytic composite powder is dried and ground to obtain the quantum dot / bismuth halide piezoelectric-photocatalytic composite powder.
[0039] Preferably, in step S1, the main material uses bismuth oxyiodide (2 mmol) and potassium iodide, potassium bromide, or potassium chloride powder (2 mmol) (molar ratio 1:1), and the first solvent is a mixed solution of ethylene glycol (20 ml) and deionized water (ultrapure water) (20 ml) (volume ratio 1:1). By using potassium iodide, the nanoflower structure can be controlled and adjusted, significantly increasing the surface area and reactive sites of the photocatalytic piezoelectric-photocatalytic powder.
[0040] Preferably, the preparation process of the quantum dot solution in step S2 is as follows: a certain mass (0.02-2% of the total mass of the prepared bismuth halide powder) of the original bulk material is taken, uniformly ground for 5 minutes, dissolved in a second solvent, and ultrasonically exfoliated (120-150w) under an ice bath for 60-300 minutes. The second solvent is N-methylpyrrolidone, an ethanol solution (75% concentration), or an ammonia solution (25% concentration), and the mass ratio of the original bulk material to the second solvent is (0.01-0.2):10.
[0041] More preferably, the diameter of the quantum dots in the quantum dot solution of step S2 is between 2 and 50 nanometers (observed under a high-resolution electron microscope).
[0042] Preferably, in step S3, the bismuth halide and quantum dot solution recombination process involves heating in a water bath at 40–80 degrees Celsius for 2–4 hours to obtain a dark brown or gray mixed solution.
[0043] A quantum dot / bismuth halide composite powder, comprising a bismuth halide matrix and quantum dot particles deposited on its surface, wherein each bismuth halide surface is embedded with two or more quantum dot particles.
[0044] Preferably, the bismuth halide powder obtained by the present invention has a nanosheet structure with a diameter of 50 to 300 nanometers, and the quantum dot particles are smaller than 50 nanometers, concentrated in the range of 2 to 8 nanometers.
[0045] The application of a quantum dot / bismuth halide composite powder preparation method in the field of piezoelectric-photocatalysis, specifically in the preparation of piezoelectric-photocatalytic composite powder.
[0046] A piezoelectric-photocatalytic system includes the aforementioned quantum dot / bismuth halide composite powder. An internal electric field is formed by external mechanical energy driving the formation of the internal field. The photogenerated charge carriers include electrons and holes, which carry positive and negative charges respectively. Therefore, they move in opposite directions under the action of the internal electric field, which helps to further improve the separation efficiency of photogenerated charge carriers and holes. Only when photogenerated charge carriers, namely electrons and holes, are separated in space can photocatalytic performance, such as the degradation of organic matter, be achieved. Thus, the piezoelectric effect is used to improve the photocatalytic efficiency.
[0047] This invention modifies the surface of bismuth halide nanosheets with quantum dots to form a compact heterostructure, constructs a rapid transfer pathway for photogenerated carriers, and couples the mechanical energy generated by ultrasound to prepare highly efficient piezoelectric-photocatalytic composite powders.
[0048] Quantum dot / bismuth halide composite materials possess excellent visible light absorption, stable piezoelectricity, and a large specific surface area, making them suitable for applications in energy conversion, nanogenerators, and piezoelectric-photocatalysis. Quantum dot / bismuth halide composite catalyst powders organically combine photocatalytic heterojunction theory and piezoelectric catalysis systems, leveraging synergistic effects to further promote the separation and migration of photogenerated carriers. This overcomes the limitations of single materials and expands the application scope of photocatalysis.
[0049] The present invention will be further described in detail below through specific embodiments.
[0050] Example 1
[0051] This embodiment describes a method for preparing quantum dot / bismuth halide composite powder, the steps of which are as follows:
[0052] S1, bismuth oxyiodide (2 mmol) and potassium bromide (2 mmol) were added to a mixed solution of ethylene glycol (20 ml) and deionized water (20 ml) (volume ratio 1:1) in a molar ratio of 1:1. The mixture was heated in an oil bath at 80°C for two hours. After the reaction system cooled to room temperature, it was centrifuged, dried and ground to obtain bismuth oxyiodide powder.
[0053] S2. Take a certain mass of the original titanium carbide block, grind it evenly for 5 minutes, dissolve it in 20 ml of ammonia solution, ultrasonically peel it for 300 minutes in an ice bath (power 120-150w), centrifuge it at 11000 rpm for 10 minutes, filter the precipitate, and finally obtain the titanium carbide quantum dot solution.
[0054] S3. Mix the bismuth oxybromide powder and the titanium carbide quantum dot solution, and heat in a water bath at 70-80°C for 3 hours; the quantum dots account for 0.15% of the total weight of the bismuth oxybromide powder (calculated based on raw material ratio).
[0055] S4. The modified titanium carbide quantum dot / bismuth oxybromide composite powder is centrifuged, dried and ground to obtain the titanium carbide quantum dot / bismuth oxybromide piezoelectric-photocatalytic composite powder.
[0056] Figure 1 The image shown is an HRTEM image of the titanium carbide quantum dots prepared in this embodiment. The quantum dots are uniformly spherical in size and less than 50 nm, with the diameter basically distributed between 2 and 8 nanometers.
[0057] Figure 2 The image shows the XRD patterns of the titanium carbide quantum dot / bismuth oxybromide composite powder before and after use in this embodiment. The crystal structure did not change before and after use.
[0058] Figure 3 The figure shows the EDX spectrum of the titanium carbide quantum dot / bismuth oxybromide composite powder. As can be seen from the figure, the prepared powder is basically consistent with the designed composition.
[0059] Example 2
[0060] This embodiment describes a method for preparing quantum dot / bismuth halide composite powder, the steps of which are as follows:
[0061] S1, bismuth oxyiodide (2 mmol) and potassium iodide were added to a mixed solution of ethylene glycol (20 ml) and deionized water (volume ratio 1:1) in a molar ratio of 1:1. The mixture was heated in an oil bath at 80 degrees Celsius for two hours. After the reaction system cooled to room temperature, it was centrifuged, dried and ground to obtain bismuth oxyiodide powder.
[0062] S2. Take a certain mass of the original black phosphorus block, grind it evenly for 5 minutes, dissolve it in 20 ml of N-methylpyrrolidone solution, ultrasonically peel it for 60 minutes in an ice bath, centrifuge it at 11000 rpm for 10 minutes, filter the precipitate, and finally obtain the black phosphorus quantum dot solution.
[0063] S3. Mix the bismuth oxyiodine powder and the black phosphorus quantum dot solution, and the quantum dots account for 0.05% of the total weight percentage of the bismuth oxyiodine powder after the composite is formed.
[0064] S4. The modified black phosphorus quantum dot / bismuth oxyiodine composite powder is centrifuged, dried and ground to obtain the black phosphorus quantum dot / bismuth oxyiodine piezoelectric-photocatalytic composite powder.
[0065] Example 3
[0066] This embodiment describes a method for preparing quantum dot / bismuth halide composite powder, the steps of which are as follows:
[0067] S1, bismuth oxyiodide (2 mmol), and potassium bromide were added to a mixed solution of ethylene glycol (20 ml) and deionized water (volume ratio 1:1) in a molar ratio of 1:1. The mixture was heated in an oil bath at 80 degrees Celsius for two hours. After the reaction system cooled to room temperature, it was centrifuged, dried, and ground to obtain bismuth oxyiodide powder.
[0068] S2. Take a certain mass of the original black phosphorus block, grind it evenly for 5 minutes, dissolve it in 20 ml of N-methylpyrrolidone solution, ultrasonically peel it for 60 minutes in an ice bath, centrifuge it at 11000 rpm for 10 minutes, filter the precipitate, and finally obtain the black phosphorus quantum dot solution.
[0069] S3. Mix the bismuth oxybromine powder and the black phosphorus quantum dot solution, and after the mixture is combined, the quantum dots account for 0.1% of the total weight percentage of the bismuth oxybromine powder.
[0070] S4. The modified black phosphorus quantum dot / bismuth oxybromide composite powder is centrifuged, dried and ground to obtain the black phosphorus quantum dot / bismuth oxybromide piezoelectric-photocatalytic composite powder.
[0071] For the preparation method of quantum dots / bismuth halide provided by this invention, specific preparation examples and comparative examples are listed in Table 1. Table 1 examines the selection of bismuth halide material in step S1 (labeled A). The selection of quantum dot material in step S2 (labeled B). The selection of the weight percentage of quantum dots in the total weight of bismuth halide powder in step S3 (labeled C).
[0072] Table 1. Material selection and weight percentage in various embodiments of the present invention.
[0073]
[0074]
[0075] Figure 4 The fluorescence spectra of the titanium carbide quantum dot / bismuth oxybromide composite powders prepared in Examples 1, 10 and 11 of this invention have similar characteristic peaks.
[0076] Comparative Example 1
[0077] The only difference from Example 1 is that the temperature of the oil bath in step S1 is adjusted to 120°C, while the other steps and conditions are the same as in Example 1.
[0078] like Figure 5As shown, (a) shows the morphology of bismuth oxybromine powder prepared at low temperature (80°C) in Example 1, and (b) shows the morphology of bismuth oxybromine powder prepared at high temperature (120°C) in Comparative Example 1. The two are different, in which nanosheet structures can be prepared at low temperature.
[0079] Application Example 1
[0080] The photocatalytic powder prepared in Example 2 was subjected to application testing.
[0081] The prepared powders were subjected to piezoelectric catalysis, photocatalysis, and piezoelectric photocatalysis tests. A 400W halogen lamp and a 150W ultrasonic cleaner were used. The powder sample dosage was 0.1-1 g / L, and the test solution was methyl violet (MV 20 mg / L, 50 ml). The test time was 1 hour, with 3 ml of solution taken every 15 minutes, centrifuged, and the supernatant collected. The solution concentration was analyzed by UV-Vis assay. The test was repeated 10 times per application.
[0082] Figure 6 Degradation curves (MV, 20 mg / L, 50 ml) under different conditions (a) visible light, b) ultrasonic vibration, c) visible light and ultrasonic vibration. Figure 6 It is evident that the photocatalytic conditions formed only under visible light in (a) and the piezoelectric catalytic conditions formed only under ultrasonic vibration in (b) are not as effective as the degradation effect of the combined effects of visible light and ultrasonic vibration in (c) after 15 min. The degradation rate in (c) is about 55% after 15 min (the degradation rate of a single treatment is only between 30 and 35%), and the degradation equilibrium is basically reached after 45 min, with a degradation rate of over 85%. In contrast, the degradation rate of a single treatment with visible light or ultrasound is only about 55% after 60 min. This indicates that the quantum dot / bismuth oxyhalide composite catalyst powder of the present invention can organically combine the photocatalytic heterojunction theory and the piezoelectric catalytic system to exert a synergistic effect.
[0083] Compared with existing technologies, this invention provides a quantum dot / bismuth halide composite piezoelectric-photocatalytic powder and its preparation method, comprising the following steps: preparing bismuth halide by oil bath heating, followed by drying and grinding to obtain bismuth halide powder; exfoliating quantum dots from the bulk raw material by liquid phase exfoliation; depositing quantum dots on the surface of the bismuth halide powder using ethanol as a solvent to obtain a quantum dot / bismuth halide composite powder; the mass percentage of quantum dots in the composite is 0.02-2% of the total weight of bismuth halide; drying and grinding the composite powder to obtain the quantum dot / bismuth halide composite piezoelectric-photocatalytic powder. This invention uses an oil bath heating method to modify the surface of the bismuth halide powder with quantum dots, improving the interfacial bonding between the quantum dots and the bismuth halide powder, increasing the specific surface area of the composite catalyst, enhancing the separation and migration of photogenerated carriers at the heterojunction interface, fully utilizing the synergistic effect of mechanical and light energy, and constructing a more efficient composite catalyst powder.
[0084] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.
Claims
1. An application of a quantum dot / bismuth halide composite powder in the piezoelectric-photocatalytic degradation of methyl violet, characterized in that: The preparation method of the quantum dot / bismuth halide composite powder includes the following steps: S1, bismuth oxyiodide and potassium iodide were added to a mixed solution of ethylene glycol and deionized water in a molar ratio of 1:
1. The mixture was heated in an oil bath at 80 degrees Celsius for two hours. After the reaction system cooled to room temperature, it was centrifuged, dried and ground to obtain bismuth oxyiodide powder. The amount of bismuth oxyiodide used was 2 mmol, the amount of ethylene glycol was 20 mL, and the volume ratio of ethylene glycol to deionized water was 1:
1. S2. Take a certain mass of the original black phosphorus block, grind it evenly for 5 minutes, dissolve it in 20 ml of N-methylpyrrolidone solution, ultrasonically peel it for 60 minutes in an ice bath, centrifuge it at 11000 rpm for 10 minutes, filter the precipitate, and finally obtain the black phosphorus quantum dot solution. S3. The bismuth oxyiodide powder and the black phosphorus quantum dot solution are mixed, and the black phosphorus quantum dots account for 0.05% of the total weight of the bismuth oxyiodide powder after the composite is formed. S4. The modified black phosphorus quantum dot / bismuth oxyiodine composite powder is centrifuged, dried and ground to obtain the black phosphorus quantum dot / bismuth oxyiodine piezoelectric-photocatalytic composite powder.