A multi-level hollow blue titanium dioxide microsphere material, its preparation method and application
By synthesizing hierarchical hollow blue titanium dioxide microspheres via a solvothermal method, the problems of instability and low photocatalytic efficiency of hollow TiO2 structure were solved, achieving good stability and high efficiency in visible light photocatalysis.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-11-15
- Publication Date
- 2026-03-13
AI Technical Summary
The existing hollow structure of TiO2 is unstable and has low photocatalytic efficiency, large mass transfer resistance, and high recombination rate of photogenerated electrons and holes, making it difficult to effectively utilize visible light.
Multi-level hollow blue titanium dioxide microspheres were synthesized by a solvothermal method. Vertical channels were formed by the self-assembly of dendritic nano-TiO2 to regulate oxygen defect concentration and crystal phase composition, reduce mass transfer resistance, and enhance visible light response.
The prepared hierarchical hollow blue titanium dioxide microspheres exhibit good stability, low mass transfer resistance, large specific surface area, and excellent visible light photocatalytic activity, enabling them to effectively degrade organic pollutants.
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Figure CN117566788B_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of micro / nano material preparation and the interdisciplinary fields of environmental chemistry and photocatalysis, specifically relating to a multi-level hollow blue titanium dioxide microsphere material, its preparation method and application. Background Technology
[0002] Among numerous semiconductor photocatalytic materials, TiO2 stands out for its excellent physicochemical properties, including low cost, non-toxicity, high photocatalytic activity, and strong stability (resistance to chemical and photocorrosion). It is widely used in environmental purification, photocatalytic water splitting for hydrogen production, and novel solar cells, making it one of the most promising photocatalytic materials for practical applications. It is well known that changes in the structure and morphology of a material can alter its optical, electrical, mechanical, and catalytic properties to a certain extent. Therefore, extensive research has focused on synthesizing TiO2 materials with special structures and morphologies, particularly hollow TiO2 microspheres. On the one hand, hollow spheres have a large specific surface area, and their hollow structure facilitates the enrichment and diffusion of reactant molecules, increasing the reaction rate. On the other hand, the hollow structure facilitates light diffraction and reflection; through multiple reflections of light within the hollow spheres, photocatalytic efficiency is significantly improved. However, current traditional hollow TiO2 materials are mostly composed of nanoscale particle stacking, with the pores within the shell primarily consisting of inter-particle packing pores. These pores are tortuous, small in size, and non-uniform. Therefore, a thicker shell will lead to a sharp increase in mass transfer resistance, while a thinner shell will make the shell more prone to damage, resulting in instability of the hollow structure.
[0003] Furthermore, TiO2 is a wide-bandgap semiconductor material that can only be excited by ultraviolet light, and its surface has a high recombination rate of photogenerated electrons and holes, resulting in low photocatalytic efficiency and greatly limiting its potential as a solar photocatalyst. In recent years, researchers have used methods such as elemental doping, narrow-bandgap semiconductor recombination, or high-temperature reduction to functionalize TiO2 and expand its photoresponse range. Among these methods, high-temperature reduction can introduce oxygen vacancies into TiO2, creating intrinsic defects and thus enabling it to exhibit photocatalytic activity under visible light. However, these methods are cumbersome, costly, and involve certain risks in the experimental procedures. Summary of the Invention
[0004] To address the instability and low photocatalytic efficiency of current central control structures, this application provides a multi-level hollow blue titanium dioxide microsphere material. The prepared multi-level hollow microspheres are self-assembled from dendritic nano-TiO2, which has advantages such as low mass transfer resistance and large specific surface area. Moreover, the prepared TiO2 multi-level hollow microsphere material is blue, has good stability, and has adjustable crystal phase composition, oxygen vacancy concentration, and good visible light photocatalytic activity.
[0005] The proposed solution is as follows:
[0006] A multi-level hollow blue titanium dioxide microsphere material is prepared by means of the following raw materials: solution A; solution B and TiCl3; solution A is a mixture of organic alcohol 1 and polyethylene glycol; solvent B is a mixture of urea and organic alcohol 2; the raw materials are mixed and then subjected to a hydrothermal reaction.
[0007] Preferably, the volume ratio of polyethylene glycol to organic alcohol 1 is 1:(1.8-3.6); and / or the amount ratio of urea to organic alcohol 2 is (0.24-0.8) g:1 ml; and / or the TiCl3 needs to be prepared as a solution, the TiCl3 solution being a 15% by mass solution, and the volume ratio of TiCl3 solution to organic alcohol being 1:(1.5-3). The purchased TiCl3 solution used in this application contains approximately 20% hydrochloric acid because trivalent titanium is easily hydrolyzed and requires an acidic system for protection to maintain stability.
[0008] Preferably, the polyethylene glycol has a molecular weight of 200-600 Da; and / or, organic alcohol 1 is one or more of methanol, ethanol, and ethylene glycol; and / or, organic alcohol 2 is one or more of methanol, ethanol, and ethylene glycol. Organic alcohol 1 and organic alcohol 2 may be the same or different.
[0009] Preferably, the mixture further includes adjusting the pH to 0.5-1.2 after mixing.
[0010] Another object of the present invention is to protect the preparation method of the above-mentioned multi-level hollow blue titanium dioxide microsphere material, comprising the following steps:
[0011] (1) Add polyethylene glycol to organic alcohol 1 and stir until homogeneous to obtain solution A;
[0012] (2) Add urea to organic alcohol 2 and dissolve it completely to obtain solution B;
[0013] (3) Add solution B to solution A and stir until homogeneous to obtain solution C;
[0014] (4) Add TiCl3 solution to solution C and stir until a purple solution is obtained;
[0015] (5) After stirring the solution obtained in step (4) evenly, a solvothermal reaction is carried out. After the reaction is completed, the solution is centrifuged, washed and dried to obtain blue TiO2 hierarchical hollow microsphere material.
[0016] Further, after obtaining the purple solution in step (4), the pH is adjusted to 0.5-1.2; and / or the pH of the system is adjusted to 0.5-1.2 with an ammonia solution.
[0017] Further, step (5) is carried out by stirring at room temperature; and / or, the conditions for the solvothermal reaction are 120-160°C for 10-24 h; and / or, the washing is washing with deionized water 3-5 times, and then washing with anhydrous ethanol 2-3 times; and / or, the drying is vacuum drying at 55-60°C for 5-10 h.
[0018] Another objective of this invention is to protect the above-mentioned multi-level hollow blue titanium dioxide microsphere material, wherein the concentration of reactive oxygen species defects in the material can be controlled by changing the pH of the system; and / or, the material is a mixed crystal of rutile and anatase; and / or, the ratio of rutile to anatase in the material can be controlled by the amount of urea added.
[0019] Another object of the present invention is to protect the application of the above-mentioned multi-level hollow blue titanium dioxide microsphere material as a photocatalyst.
[0020] Furthermore, the application is in the photocatalytic degradation of Rhodamine B.
[0021] Using inexpensive TiCl3 solution as a raw material, a one-step hydrothermal synthesis of hierarchical hollow blue titanium dioxide microspheres was achieved through optimized reaction conditions. The hierarchical hollow blue titanium dioxide microspheres prepared by this method are self-assembled from dendritic TiO2 nanoneedles, possessing radially distributed linear channels perpendicular to the outer shell and uniform pore size. This results in advantages such as low mass transfer resistance and large specific surface area for the hierarchical hollow microspheres.
[0022] The prepared hierarchical hollow blue titanium dioxide microspheres contain a large number of active oxygen defect sites, which effectively reduces the band gap of TiO2 and the recombination rate of photogenerated electrons and holes, and enhances its response to visible light. Under visible light irradiation, its photocatalytic degradation effect of rhodamine B is better than that of commercial titanium dioxide P25, and the oxygen defect concentration in the material can be controlled by changing the pH of the system.
[0023] The multi-level hollow blue titanium dioxide microsphere material of this invention is a mixed crystal of rutile and anatase, and the ratio of rutile to anatase can be controlled by the amount of urea added.
[0024] Beneficial effects of the present invention
[0025] The hollow spherical shell prepared in this application is composed of a large number of dendritic TiO2 nanoparticles. These dendritic particles are intertwined through branches, ensuring the stability of the shell while maintaining its permeability and reducing mass transfer resistance. The multi-level structure of this application... Figure 1 SEM and Figure 2 The TEM image shows that a micron-sized hollow TiO2 sphere structure is composed of a large number of dendritic TiO2 nanoparticles.
[0026] This invention proposes a simple solvothermal method for one-step synthesis of hierarchical hollow blue titanium dioxide microspheres. The synthesis process requires no complex surfactants or additives, is simple in structure and short in cycle, and does not require a vacuum environment or protective gas, which is beneficial for large-scale production. Furthermore, the morphology, crystal form, and oxygen vacancy concentration of the prepared hierarchical hollow blue titanium dioxide microspheres are tunable, and they possess advantages such as low mass transfer resistance and large specific surface area. They exhibit high photocatalytic performance under visible light, enabling the complete degradation of organic pollutants such as dyes. They can also be used in photocatalytic water splitting, supercapacitors, etc., and have strong market application prospects.
[0027] Finally, this invention avoids the use of complex and expensive surfactants or templates, and the method is simple, has a short cycle, and the reaction process does not require a vacuum environment or protective gas, which is conducive to large-scale production. Attached Figure Description
[0028] Figure 1 This is a SEM image of the hierarchical hollow blue titanium dioxide microsphere material prepared in Example 1;
[0029] Figure 2 This is a TEM image of the hierarchical hollow blue titanium dioxide microsphere material prepared in Example 1;
[0030] Figure 3 The UV-Dr comparison image shows the hierarchical hollow blue titanium dioxide microspheres prepared in Example 1 and commercial titanium dioxide P25.
[0031] Figure 4 This is a SEM image of the multi-level hollow blue titanium dioxide microsphere material prepared in Example 2;
[0032] Figure 5 The above are comparison images of the EPR of the multi-level hollow blue titanium dioxide microspheres prepared in Examples 1 and 3.
[0033] Figure 6 This is a comparison of the performance of the multi-level hollow blue titanium dioxide microspheres prepared in Examples 1 and 3 with that of commercial P25 in degrading Rhodamine B under visible light.
[0034] Figure 7 The images show the XRD patterns of the hierarchical hollow blue titanium dioxide microspheres prepared in Examples 1, 4, and 5.
[0035] Figure 8 This is a comparison of the optical colors of the titanium dioxide products prepared in Comparative Example 1 and Example 1.
[0036] Figure 9SEM image of the titanium dioxide product prepared in Comparative Example 1. Detailed Implementation
[0037] Example 1
[0038] A method for preparing a multi-level hollow blue titanium dioxide microsphere material includes the following steps:
[0039] (1) Take 25 ml of anhydrous ethanol and add it to a three-necked flask. Then add 12 ml of polyethylene glycol 200 Da to the ethanol and stir well to obtain solution A.
[0040] (2) Add 2.4g of urea to 5ml of anhydrous ethanol and stir for 20min to dissolve it completely to obtain solution B;
[0041] (3) Add solution B to solution A and stir until homogeneous to obtain solution C;
[0042] (4) Add 12 ml of TiCl3 solution to solution C, stir well to obtain a purple solution, and then add ammonia solution to adjust the pH of the system to 0.8.
[0043] (5) After stirring the solution obtained in step (4) at 25°C for 60 min, it was quickly transferred to a high-pressure reactor with a polytetrafluoroethylene liner and subjected to a solvothermal reaction at 150°C for 12 hours. After the reaction was completed, the product was separated by centrifugation, washed three times each with anhydrous ethanol and deionized water, and then placed in a vacuum drying oven at 60°C for 10 h to obtain multi-level hollow blue titanium dioxide microspheres.
[0044] Figure 1 and Figure 2 The images shown are SEM and TEM images of the multi-level hollow blue titanium dioxide microspheres prepared in this embodiment. It can be seen that the multi-level hollow blue titanium dioxide microspheres are assembled from a large number of dendritic nanoparticles and have obvious hollow cavities. Figure 3 The image shows a comparison of the UV-Vis spectra of the hierarchical hollow blue titanium dioxide microspheres prepared in this embodiment and commercial titanium dioxide P25. It can be seen that the absorption band edge of the hierarchical hollow blue titanium dioxide microspheres synthesized in this embodiment is significantly better than that of commercial titanium dioxide P25, and it also has obvious light absorption in the visible light region (wavelength > 400 nm).
[0045] Example 2
[0046] A method for preparing a multi-level hollow blue titanium dioxide microsphere material includes the following steps:
[0047] (1) Take 25 ml of anhydrous methanol and add it to a three-necked flask. Then add 12 ml of polyethylene glycol 400 Da to the methanol and stir well to obtain solution A.
[0048] (2) Add 2.4g of urea to 5ml of anhydrous methanol and stir for 20min to dissolve it completely to obtain solution B;
[0049] (3) Add solution B to solution A and stir until homogeneous to obtain solution C;
[0050] (4) Add 12 ml of TiCl3 solution to solution C, stir well to obtain a purple solution, and then add ammonia solution to adjust the pH of the system to 0.8.
[0051] (5) After stirring the solution obtained in step (4) at 25°C for 60 min, it was quickly transferred to a high-pressure reactor with a polytetrafluoroethylene liner and subjected to a solvothermal reaction at 120°C for 12 hours. After the reaction was completed, the product was separated by centrifugation, washed three times each with anhydrous ethanol and deionized water, and then placed in a vacuum drying oven at 60°C for 10 h to obtain multi-level hollow blue titanium dioxide microspheres.
[0052] Figure 4 The image shows a SEM image of the hierarchical hollow blue titanium dioxide microspheres prepared in this embodiment. It can be seen that the hierarchical hollow blue titanium dioxide microspheres are assembled from a large number of dendritic nanoparticles and have obvious hollow cavities.
[0053] Example 3
[0054] A method for preparing a multi-level hollow blue titanium dioxide microsphere material includes the following steps:
[0055] (1) Take 25 ml of anhydrous ethanol and add it to a three-necked flask. Then add 12 ml of polyethylene glycol 200 Da to the ethanol and stir well to obtain solution A.
[0056] (2) Add 2.4g of urea to 5ml of anhydrous ethanol and stir for 20min to dissolve it completely to obtain solution B;
[0057] (3) Add solution B to solution A and stir until homogeneous to obtain solution C;
[0058] (4) Add 12 ml of TiCl3 solution to solution C, stir well to obtain a purple solution, and then add ammonia solution to adjust the pH of the system to 1.0;
[0059] (5) After stirring the solution obtained in step 4 at 25°C for 60 min, it was quickly transferred to a high-pressure reactor with a polytetrafluoroethylene liner and subjected to a solvothermal reaction at 150°C for 12 hours. After the reaction was completed, the product was separated by centrifugation, washed three times each with anhydrous ethanol and deionized water, and then placed in a vacuum drying oven at 60°C for 10 h to obtain multi-level hollow blue titanium dioxide microspheres.
[0060] Figure 5 The EPR comparison images of the hierarchical hollow blue titanium dioxide microspheres prepared in Examples 1 and 3 show that both samples exhibit a distinct EPR signal peak at g = 2.003, confirming the presence of oxygen vacancies in both samples. Furthermore, the EPR signal intensity of the sample prepared in Example 3 is significantly higher than that in Example 1, indicating a higher oxygen vacancy concentration in the sample prepared in Example 3. This confirms that the oxygen vacancy concentration in the hierarchical hollow blue titanium dioxide microspheres can be controlled by adjusting the pH. Figure 6 The photocatalytic degradation curves of the organic dye Rhodamine B by the hierarchical hollow blue titanium dioxide microspheres prepared in Examples 1 and 3 under visible light are shown.
[0061] Example 4
[0062] A method for preparing a multi-level hollow blue titanium dioxide microsphere material includes the following steps:
[0063] (1) Take 25 ml of anhydrous ethanol and add it to a three-necked flask. Then add 12 ml of polyethylene glycol 200 Da to the ethanol and stir well to obtain solution A.
[0064] (2) Add 1.8g of urea to 5ml of anhydrous ethanol and stir for 20min to dissolve it completely to obtain solution B;
[0065] (3) Add solution B to solution A and stir until homogeneous to obtain solution C;
[0066] (4) Add 12 ml of TiCl3 solution to solution C, stir well to obtain a purple solution, and then add ammonia solution to adjust the pH of the system to 0.8.
[0067] (5) After stirring the solution obtained in step 4 at 25°C for 60 min, it was quickly transferred to a high-pressure reactor with a polytetrafluoroethylene liner and subjected to a solvothermal reaction at 150°C for 12 hours. After the reaction was completed, the product was separated by centrifugation, washed three times each with anhydrous ethanol and deionized water, and then placed in a vacuum drying oven at 60°C for 10 h to obtain multi-level hollow blue titanium dioxide microspheres.
[0068] Example 5
[0069] A method for preparing a multi-level hollow blue titanium dioxide microsphere material includes the following steps:
[0070] (1) Take 25 ml of anhydrous ethanol and add it to a three-necked flask. Then add 12 ml of polyethylene glycol 200 Da to the ethanol and stir well to obtain solution A.
[0071] (2) Add 1.2g of urea to 5ml of anhydrous ethanol and stir for 20min to dissolve it completely to obtain solution B;
[0072] (3) Add solution B to solution A and stir until homogeneous to obtain solution C;
[0073] (4) Add 12 ml of TiCl3 solution to solution C, stir well to obtain a purple solution, and then add ammonia solution to adjust the pH of the system to 1.0;
[0074] (5) After stirring the solution obtained in step (4) at 25°C for 60 min, it was quickly transferred to a high-pressure reactor with a polytetrafluoroethylene liner and subjected to a solvothermal reaction at 150°C for 12 hours. After the reaction was completed, the product was separated by centrifugation, washed three times each with anhydrous ethanol and deionized water, and then placed in a vacuum drying oven at 60°C for 10 h to obtain multi-level hollow blue titanium dioxide microspheres.
[0075] Figure 7 The XRD patterns of the multi-level hollow blue titanium dioxide microspheres prepared in Examples 1, 4 and 5 show that the crystal phase structure of the products can be controlled by changing the amount of urea added.
[0076] Example 6
[0077] A method for preparing a multi-level hollow blue titanium dioxide microsphere material includes the following steps:
[0078] (1) Take 25 ml of ethylene glycol and add it to a three-necked flask. Then add 12 ml of polyethylene glycol 200 Da to the ethylene glycol and stir well to obtain solution A.
[0079] (2) Add 2.4g of urea to 5ml of anhydrous methanol and stir for 20min to dissolve it completely to obtain solution B;
[0080] (3) Add solution B to solution A and stir until homogeneous to obtain solution C;
[0081] (4) Add 12 ml of TiCl3 solution to solution C, stir well to obtain a purple solution, and then add ammonia solution to adjust the pH of the system to 0.5;
[0082] (5) After stirring the solution obtained in step (4) at 25°C for 60 min, it was quickly transferred to a high-pressure reactor with a polytetrafluoroethylene liner and subjected to a solvothermal reaction at 160°C for 10 h. After the reaction was completed, the product was separated by centrifugation, washed three times each with anhydrous ethanol and deionized water, and then placed in a vacuum drying oven at 60°C for 10 h to obtain multi-level hollow blue titanium dioxide microspheres.
[0083] Example 7
[0084] A method for preparing a multi-level hollow blue titanium dioxide microsphere material includes the following steps:
[0085] (1) Take 25 ml of anhydrous methanol and add it to a three-necked flask. Then add 12 ml of polyethylene glycol 600 Da to the methanol and stir well to obtain solution A.
[0086] (2) Add 4.0g of urea to 5ml of anhydrous ethanol and stir for 20min to dissolve it completely to obtain solution B;
[0087] (3) Add solution B to solution A and stir until homogeneous to obtain solution C;
[0088] (4) Add 12 ml of TiCl3 solution to solution C, stir well to obtain a purple solution, and then add ammonia solution to adjust the pH of the system to 1.2;
[0089] (5) After stirring the solution obtained in step (4) at 25°C for 60 min, it was quickly transferred to a high-pressure reactor with a polytetrafluoroethylene liner and subjected to a solvothermal reaction at 150°C for 12 hours. After the reaction was completed, the product was separated by centrifugation, washed three times each with anhydrous ethanol and deionized water, and then placed in a vacuum drying oven at 60°C for 10 h to obtain multi-level hollow blue titanium dioxide microspheres.
[0090] Comparative Example 1
[0091] A method for preparing titanium dioxide material includes the following steps:
[0092] (1) Take 25 ml of anhydrous ethanol and add it to a three-necked flask. Then add 12 ml of polyethylene glycol 200 Da to the ethanol and stir well to obtain solution A.
[0093] (2) Add 2.4g of urea to 5ml of anhydrous ethanol and stir for 20min to dissolve it completely to obtain solution B;
[0094] (3) Add solution B to solution A and stir until homogeneous to obtain solution C;
[0095] (4) Add 10 ml of TiCl3 solution to solution C and stir until a purple solution is obtained;
[0096] (5) After stirring the solution obtained in step (4) at 25°C for 60 min, it was quickly transferred to a high-pressure reactor with a polytetrafluoroethylene liner and subjected to a solvothermal reaction at 160°C for 12 hours. After the reaction was completed, the product was separated by centrifugation, washed three times each with anhydrous ethanol and deionized water, and then placed in a vacuum drying oven at 60°C for 10 h to obtain multi-level hollow blue titanium dioxide microspheres.
[0097] Figure 8 The optical color comparison diagram of the titanium dioxide products prepared in Comparative Example 1 and Example 1 shows that the product in Comparative Example 1 is white, while the product in Example 1 is dark blue. Figure 9 The image shows a SEM image of the titanium dioxide product prepared in Comparative Example 1. The product has a non-hollow structure composed of coarse rod-shaped particles.
Claims
1. A method for preparing a multi-level hollow blue titanium dioxide microsphere material, characterized in that, Includes the following steps: (1) Add polyethylene glycol to organic alcohol 1 and stir until homogeneous to obtain solution A; (2) Add urea to organic alcohol 2 and dissolve it completely to obtain solution B; (3) Add solution B to solution A and stir until homogeneous to obtain solution C; (4) Add TiCl3 solution to solution C and stir until a purple solution is obtained; (5) After stirring the solution obtained in step (4) evenly, a solvothermal reaction is carried out. After the reaction is completed, the solution is centrifuged, washed and dried to obtain blue TiO2 hierarchical hollow microsphere material. The solvothermal reaction conditions are 120-160℃ for 10-24 hours; After obtaining the purple solution in step (4), adjust the pH to 0.5-1.2; The molecular weight of the polyethylene glycol is 200-600 Da; The organic alcohol 1 is one or more of methanol, ethanol, and ethylene glycol; The organic alcohol 2 is one or more of methanol, ethanol, and ethylene glycol; The volume ratio of polyethylene glycol to organic alcohol 1 is 1:(1.8-3.6); The ratio of urea to organic alcohol 2 is (0.24-0.8) g: 1 ml.
2. The preparation method according to claim 1, characterized in that, The TiCl3 solution has a mass percentage of 15%, and the volume ratio of TiCl3 solution to organic alcohol is 1:(1.5-3).
3. The preparation method according to claim 1, characterized in that, In step (4), the pH value of the system is adjusted using an ammonia solution.
4. The preparation method according to any one of claims 1-3, characterized in that, The stirring in step (5) is carried out at room temperature; And / or, the washing is to wash with deionized water 3-5 times, and then wash with anhydrous ethanol 2-3 times; And / or, the drying is carried out at 55-60°C under vacuum for 5-10 hours.
5. A multi-level hollow blue titanium dioxide microsphere material prepared by the preparation method according to any one of claims 1-4, characterized in that, The concentration of reactive oxygen species defects in the material is controlled by changing the pH of the system. And / or, the material is a mixed crystal of rutile and anatase; And / or, the ratio of rutile to anatase in the material is controlled by the amount of urea added.
6. The application of a multi-level hollow blue titanium dioxide microsphere material prepared by any one of the preparation methods described in claims 1-4 as a photocatalyst.
7. The application according to claim 6, characterized in that, The application described is in the photocatalytic degradation of Rhodamine B.