A TiO2 / BN hydrosol with high solid content and high catalytic efficiency, and its preparation method and application

Abstract

The present invention provides a TiO2 / BN hydrosol with high solid content and high catalytic efficiency, and a preparation method and application thereof. The present invention combines the mechanical ball milling method and the liquid phase exfoliation method to simply, low-costly and batch-prepare a TiO2 / BN hydrosol with high solid content. The obtained TiO2 / BN hydrosol has high yield, good stability, is easy to store, requires cheap solvents, and its preparation method is simple and practical, fully integrating the advantages of the mechanical ball milling method and the liquid phase exfoliation method. The raw materials are cheap and easily available, which is conducive to large-scale industrial production and has significant economic and social benefits.

Description

Technical Field

[0001] The present invention relates to a TiO2 / BN hydrogel with high solid content and high catalytic efficiency, and its preparation method and application, belonging to the fields of material preparation and photocatalysis technology. Background Art

[0002] In recent years, with the acceleration of the industrialization process, the widespread application of colored dyes has made their harm to the environment and human health increasingly prominent. During the production and use of these dyes, various toxic and harmful substances can be released, leading to water pollution and a decline in air quality. As an emerging environmental governance method, photocatalysis technology shows good prospects. Photocatalysts can effectively degrade colored dyes under light irradiation and convert them into harmless substances.

[0003] Titanium dioxide (TiO2) has the characteristics of high photocatalytic activity, low cost, and environmental friendliness, and is one of the most efficient semiconductor photocatalysts at present. However, the practical application of titanium dioxide is limited by its inherent defects, such as limited light absorption range, easy recombination of electrons and holes, and insufficient surface active sites. In recent years, in order to improve the visible light absorption of TiO2, researchers have synthesized new TiO2-based composites by methods such as bismuth (Bi) doping and nitrogen (N) doping. Due to their lower band gap, these materials can effectively absorb visible light and improve the photocatalytic reaction efficiency (Li et al., 2020). Constructing a heterojunction between TiO2 and other semiconductors can effectively inhibit the recombination of electrons and holes and improve the quantum yield. For example, the heterojunction formed by TiO2 and gallium nitride (GaN) shows better photocatalytic performance and stability (Zhang et al., 2021). In addition, through surface modification technologies, such as the loading of metals / non-metals and the introduction of nanostructures, researchers have increased the surface active sites of TiO2, improved the adsorption ability of reactants, and significantly enhanced the catalytic activity of TiO2 in the degradation of organic pollutants (Chen et al., 2023).

[0004] Boron nitride (BN) is a ceramic material with high temperature resistance, wear resistance, corrosion resistance, and good thermal conductivity, and is widely used in high-temperature engineering, electronics, aerospace and other fields; due to its two-dimensional sheet structure, it has a high specific surface area and good adsorption ability, and is often used as a catalyst carrier, but it does not respond to visible light. After TiO2 and BN are combined, an interface is formed, and electrons transfer from TiO2 to BN through the interface, and the rapid separation of photo-generated electron-hole pairs is achieved by constructing a built-in electric field. However, due to the too large particle size of ordinary BN, oxygen and moisture are easily adsorbed on its surface, its surface activity is reduced, and the interaction force with the solvent is reduced, resulting in poor dispersion in the solvent. Therefore, directly mixing boron nitride with TiO2 cannot improve the photocatalytic performance.

[0005] In recent years, the methods for exfoliating BN mainly include mechanical exfoliation, chemical exfoliation, liquid-phase exfoliation, etc. Mechanical exfoliation usually obtains single-layer or few-layer BN through physical means such as tape peeling; chemical exfoliation uses chemical solvents to reduce the interlayer binding force to achieve exfoliation; liquid-phase exfoliation disperses BN powder in a liquid and combines ultrasonic treatment or high-speed stirring to promote interlayer separation to form a BN hydrogel. Mechanical exfoliation has low efficiency and is difficult to precisely control the number of exfoliated layers, and may also cause damage to the material; the chemical functionalization exfoliation method requires attention to the standard operation when using chemical drugs and requires waste treatment; liquid-phase exfoliation faces problems such as insufficient dispersion, solvent selection, and high cost. Therefore, the existing exfoliation technologies face severe challenges in obtaining BN hydrogels with high solid content and excellent dispersion, and there is an urgent need to develop an efficient and controllable BN exfoliation method to enhance the solid content and dispersion performance of BN hydrogels and improve the catalytic performance of photocatalysts.

[0006] In summary, there is an urgent need to develop a new type of TiO2 / BN composite photocatalyst. By optimizing the BN exfoliation technology, its dispersion in the aqueous phase can be improved, thereby enhancing the visible light absorption of TiO2 and the separation efficiency of photogenerated electron-hole pairs. This composite material is expected to significantly improve the activity and stability of the photocatalytic reaction and show more excellent performance in applications such as organic pollutant degradation. Summary of the Invention

[0007] Aiming at the deficiencies of the existing technology, the present invention provides a TiO2 / BN hydrogel with high solid content and high catalytic efficiency, and its preparation method and application.

[0008] The present invention combines the mechanical ball milling method and the liquid-phase exfoliation method to simply, low-costly and batch-prepare a TiO2 / BN hydrogel with high solid content. The obtained TiO2 / BN hydrogel has high yield, good stability, easy preservation, cheap solvents required, and its preparation method is simple and practical, fully integrating the advantages of the mechanical ball milling method and the liquid-phase exfoliation method. The raw materials are cheap and easy to obtain, which is conducive to large-scale industrial production and has significant economic and social benefits.

[0009] The present invention is realized through the following technical solutions:

[0010] A preparation method of a TiO2 / BN hydrogel with high solid content and high catalytic efficiency, comprising the following steps:

[0011] (1) Add BN powder into a ball milling tank, add absolute ethanol as a buffer solution, ball mill for 10 - 12 h to obtain a BN slurry. The BN slurry is dried, fully ground, and sieved to obtain a preliminary BN powder;

[0012] (2) Add the preliminary BN powder into a mixed solution of deionized water and ethanol, stir to disperse it evenly, and perform ultrasonic treatment to obtain a BN suspension with high solid content;

[0013] (3) Centrifuge the BN suspension and collect the BN supernatant.

[0014] (4) Mix the TiO₂ nanopowder in the BN supernatant and stir to obtain a uniformly transparent TiO₂ / BN solution.

[0015] (5) Slowly add polyvinylpyrrolidone (PVP) or polyethylene glycol (PEG) to the TiO₂ / BN solution and stir for 6 - 8 h to obtain a TiO₂ / BN hydrogel.

[0016] Preferably according to the present invention, in step (1), the mass - to - volume ratio of the BN powder to absolute ethanol is (1 - 5):(10 - 50), in units of g / mL.

[0017] Preferably according to the present invention, in step (1), the ball milling is carried out using steel balls with a diameter of 3 - 6 mm, the ball milling speed is 200 - 400 rpm, and the ball milling operation program is: work for 20 - 40 min and rest for 8 - 12 min.

[0018] Preferably according to the present invention, in step (1), the drying is carried out at 50 - 70 °C for 6 - 10 h, and the sieving is through a 60 - mesh sieve.

[0019] Preferably according to the present invention, in step (2), the mass - to - volume ratio of the BN powder to the mixed solution is (0.01 - 0.3):(10 - 300), in units of g / mL.

[0020] Preferably according to the present invention, in step (2), in the mixed solution of deionized water and ethanol, the volume ratio of deionized water to absolute ethanol is 1:1.

[0021] Preferably according to the present invention, in step (2), the ultrasonic treatment is carried out at 50 - 200 W for 0.5 - 2 h.

[0022] Preferably according to the present invention, in step (3), the centrifugation is carried out at 7000 - 9000 rpm for 4 - 10 min.

[0023] Preferably according to the present invention, in step (4), the mass - to - volume ratio of the TiO₂ nanopowder to the BN supernatant is (0.05 - 1):(15 - 300), in units of g / mL.

[0024] Preferably according to the present invention, in step (4), the mass ratio of the TiO₂ nanopowder to the BN dissolved in the supernatant is (0.05 - 1):(0.0015 - 0.3).

[0025] Preferably according to the present invention, in step (5), the PVP is K90 polyvinylpyrrolidone.

[0026] Preferably according to the present invention, in step (5), the weight average molecular weight of PVP is 1.3 million.

[0027] Preferably according to the present invention, in step (5), the average molecular weight of PEG is 2000.

[0028] Preferably, according to the present invention, in step (5), the mass volume ratio of PVP or PEG to TiO2 / BN solution is (0.05-0.2):(15-60), in units of g / mL.

[0029] Preferably, in step (5), PVP or PEG needs to be added slowly. If a large amount is added violently at one time, stratification, agglomeration and the like will occur. Therefore, PVP or PEG needs to be added slowly.

[0030] As a high molecular weight polymer, PVP or PEG has good solubility and compatibility, which can effectively increase the viscosity of TiO2 / BN solution, thereby improving its fluidity and application performance. At the same time, it can inhibit the precipitation and aggregation of BN and TiO2 particles, thereby maintaining the uniformity and suspension of the hydrosol. Therefore, the addition of PVP or PEG greatly improves the dispersibility of high solid content TiO2 / BN hydrosol.

[0031] A TiO2 / BN aqueous sol with high solid content and high catalytic efficiency is prepared by the method.

[0032] The above-mentioned TiO2 / BN hydrosol is used for catalytic degradation of rhodamine B aqueous solution (RhB) under ultraviolet-visible light, and the volume ratio of TiO2 / BN hydrosol to rhodamine B aqueous solution (RhB) is (5-20):(20-80).

[0033] Compared with the prior art, this application has the following beneficial effects:

[0034] 1. The present invention innovatively combines mechanical ball milling with liquid phase exfoliation to efficiently exfoliate boron nitride (BN) nanosheets. This effectively overcomes the limitations of traditional mechanical ball milling in terms of exfoliation efficiency and the shortcomings of liquid phase exfoliation in terms of dispersibility and production cost, significantly improving the controllability and repeatability of the preparation process. The process is simple and efficient, and is highly feasible for industrial production, laying the foundation for large-scale application.

[0035] 2. The TiO2 / BN hydrosol prepared by the present invention exhibits high solid content and excellent dispersion properties, making it have broad prospects in the preparation and application of various high-performance materials. Its stability and controllability make the application of BN nanosheets in the fields of composite materials, coatings and sensors more flexible, and can meet the performance requirements of high-end industries for materials.

[0036] 3. The TiO2 / BN hydrosol of the present invention innovatively enhances the absorption ability of TiO2 in the visible light range through specific technical means, successfully solves the problems of high electron-hole recombination rate and insufficient surface active sites, and significantly enhances the efficiency of the photocatalytic reaction. This synergistic effect enables the TiO2 / BN composite material to exhibit great application potential in the field of photocatalysis, solving the problem that directly mixing boron nitride with TiO2 cannot improve the photocatalytic performance.

[0037] 4. The experimental results show that the TiO2 / BN hydrosol of the present invention has a degradation efficiency of up to 99.41% for Rhodamine B (RhB) within 30 minutes, fully demonstrating its excellent performance in the photocatalytic reaction. By optimizing the light absorption characteristics of TiO2 and the enhancement effect of BN nanosheets, not only the separation of electrons and holes is effectively promoted, the catalytic activity is improved, but also the stability and durability of the photocatalyst are improved. The experimental results not only clearly demonstrate the great potential of the TiO2 / BN hydrosol in removing environmental pollutants, but also provide new research ideas and directions for the development of future high-efficiency photocatalytic materials, indicating its practical application prospects in the field of environmental governance. Description of the Drawings

[0038] Figure 1 It is a bar chart of the particle size distribution of different BN hydrosols. a is the BN hydrosol prepared in step (4) of Example 1, and b is the BN hydrosol prepared in Comparative Example 4;

[0039] Figure 2 It is a bar chart of the comparison of the solid content of different BN hydrosols.

[0040] Figure 3 It is the XRD pattern of the TiO2 / BN hydrosol prepared in Example 1, the BN hydrosol prepared in Comparative Example 1, and the TiO2 hydrosol prepared in Comparative Example 2.

[0041] Figure 4 It is the SEM image of the TiO2 / BN hydrosol prepared in Example 1. (a) is the SEM image of the TiO2 / BN hydrosol magnified 20,000 times, and (b) is the SEM image of the TiO2 / BN hydrosol magnified 50,000 times.

[0042] Figure 5 (a) is the SEM image of the TiO2 / BN hydrosol prepared in Example 1, (b) is the EDS energy spectrum of the TiO2 / BN hydrosol prepared in Example 1, and (c), (d) are the element mapping diagrams of the TiO2 / BN hydrosol prepared in Example 1.

[0043] Figure 6(a) TEM image of the BN hydrocolloid prepared in Comparative Example 1, and (b) TEM image of the TiO2 / BN hydrocolloid prepared in Example 1.

[0044] Figure 7 HRTEM image of the TiO2 / BN hydrocolloid prepared in Example 1

[0045] Figure 8 Diffuse reflectance absorption spectra of the TiO2 / BN hydrocolloid prepared in Example 1, the BN hydrocolloid prepared in Comparative Example 1, and the TiO2 hydrocolloid prepared in Comparative Example 2.

[0046] Figure 9 Photocurrent curves of the TiO2 / BN hydrocolloids prepared in Examples 1 - 3, the BN hydrocolloid prepared in Comparative Example 1, and the TiO2 hydrocolloid prepared in Comparative Example 2.

[0047] Figure 10 Impedance curves of the TiO2 / BN hydrocolloids prepared in Examples 1 - 3, the BN hydrocolloid prepared in Comparative Example 1, and the TiO2 hydrocolloid prepared in Comparative Example 2.

[0048] Figure 11 (a) RhB degradation diagrams of the TiO2 / BN hydrocolloids prepared in Examples 1 - 5, the BN hydrocolloid prepared in Comparative Example 1, and the TiO2 hydrocolloid prepared in Comparative Example 2, and (b) RhB degradation diagrams of the TiO2 / BN hydrocolloids prepared in Example 6 and Comparative Examples 6 - 10. Detailed implementation manners

[0049] The present invention will be further described below in conjunction with specific examples, and the advantages and features of the present invention will become clearer with the description. However, the examples are merely exemplary and do not constitute any limitation to the scope of the present invention. Those skilled in the art should understand that the details and forms of the technical solutions of the present invention can be modified or replaced without departing from the spirit and scope of the present invention, but these modifications and replacements all fall within the protection scope of the present invention.

[0050] Meanwhile, in the following examples, the experimental methods are all conventional methods unless otherwise specified; the reagents and materials are all commercially available unless otherwise specified; and the equipment used is all conventional equipment.

[0051] Example 1

[0052] Preparation method of TiO2 / BN hydrocolloid with high solid content and high catalytic efficiency, the steps are as follows:

[0053] (1) Add 3 g of BN powder into a ball - milling jar with a capacity of 50 mL, then add 30 mL of absolute ethanol as a buffer solution, set the rotation speed to 300 rpm, and ball - mill for 12 h;

[0054] (2) Place the ball-milled BN slurry in an oven at 60 °C and dry it for 8 h. Thoroughly grind the obtained white BN powder and sieve it through a 60-mesh sieve to obtain the preliminary BN powder.

[0055] (3) Add 30 mg of the obtained BN powder to a mixed solution of 30 mL of deionized water and ethanol (the volume ratio of deionized water to absolute ethanol is 1:1). Use a magnetic stirrer, maintain a rotation speed of 500 rpm, stir for 30 min to make it disperse evenly, and then perform ultrasonic treatment at 100 W for 1 h to obtain a BN suspension with high dispersion and high solid content.

[0056] (4) Transfer the BN suspension with high dispersion and high solid content to a test tube, centrifuge it at 8000 rpm for 5 min, and then carefully collect the BN supernatant. Add 0.1 g of TiO2 nanopowder to 30 mL of the BN supernatant and stir for 30 min to obtain a uniform and transparent TiO2 / BN solution (with a volume of approximately 30 mL).

[0057] (5) Weigh 0.1 g of PVP and slowly add it to the TiO2 / BN solution in step (4), and stir for 8 h to obtain a TiO2 / BN (the molar ratio of TiO2 / BN is 1:30) hydrogel.

[0058] Example 2

[0059] A method for preparing a TiO2 / BN hydrogel with high solid content and high catalytic efficiency, the steps are as follows:

[0060] (1) Add 3 g of BN powder to a ball mill jar with a capacity of 50 mL, then add 30 mL of absolute ethanol as a buffer solution, set the rotation speed to 300 rpm, and ball mill for 12 h.

[0061] (2) Place the ball-milled BN slurry in an oven at 60 °C and dry it for 8 h. Thoroughly grind the obtained white BN powder and sieve it through a 60-mesh sieve to obtain the preliminary BN powder.

[0062] (3) Add 30 mg of the obtained BN powder to a mixed solution of 30 mL of deionized water and ethanol (the volume ratio of deionized water to absolute ethanol is 1:1). Use a magnetic stirrer, maintain a rotation speed of 500 rpm, stir for 30 min to make it disperse evenly, and then perform ultrasonic treatment at 100 W for 1 h to obtain a BN suspension with high dispersion and high solid content.

[0063] (4) Transfer the BN suspension with high dispersion degree and high solid content into a test tube, centrifuge it at 8000 rpm for 5 min, and then carefully collect the BN supernatant; add 0.05 g of TiO2 nano powder into 30 mL of the BN supernatant, stir for 30 min to obtain a uniformly transparent TiO2 / BN solution (with a volume of about 30 mL);

[0064] (5) Weigh 0.1 g of PVP and slowly add it into the TiO2 / BN solution in step (4), stir for 8 h to obtain a TiO2 / BN (TiO2 / BN molar ratio is 1:15) hydrogel.

[0065] Example 3

[0066] A preparation method of TiO2 / BN hydrogel with high solid content and high catalytic efficiency is as follows:

[0067] (1) Add 3 g of BN powder into a ball mill jar with a capacity of 50 mL, then add 30 mL of absolute ethanol as a buffer solution, set the rotation speed to 300 rpm, and ball mill for 12 h;

[0068] (2) Place the ball-milled BN slurry in an oven at 60 °C and dry for 8 h. Thoroughly grind the obtained white BN powder, sieve it through a 60-mesh sieve to obtain a preliminary BN powder;

[0069] (3) Add 30 mg of the obtained BN powder into a mixed solution of 30 mL of deionized water and ethanol (the volume ratio of deionized water to absolute ethanol is 1:1), use a magnetic stirrer to keep the rotation speed at 500 rpm, stir for 30 min to make it disperse evenly, and then perform ultrasonic treatment at 100 W for 1 h to obtain a BN suspension with high dispersion degree and high solid content;

[0070] (4) Transfer the BN suspension with high dispersion degree and high solid content into a test tube, centrifuge it at 8000 rpm for 5 min, and then carefully collect the BN supernatant; add 0.2 g of TiO2 nano powder into 30 mL of the BN supernatant, stir for 30 min to obtain a uniformly transparent TiO2 / BN solution (with a volume of about 30 mL);

[0071] (5) Weigh 0.1 g of PVP and slowly add it into the TiO2 / BN solution in step (4), stir for 8 h to obtain a TiO2 / BN (TiO2 / BN molar ratio is 1:60) hydrogel.

[0072] Example 4

[0073] A preparation method of TiO2 / BN hydrogel with high solid content and high catalytic efficiency is as follows:

[0074] (1) Add 3 g of BN powder into a ball milling jar with a capacity of 50 mL, and then add 30 mL of absolute ethanol as a buffer solution. Set the rotation speed to 300 rpm and ball mill for 12 h;

[0075] (2) Place the ball-milled BN slurry in an oven at 60 °C and dry for 8 h. Thoroughly grind the obtained white BN powder and sieve it through a 60-mesh sieve to obtain the preliminary BN powder;

[0076] (3) Add 30 mg of the obtained BN powder into a mixed solution of 30 mL of deionized water and ethanol (the volume ratio of deionized water to absolute ethanol is 1:1). Use a magnetic stirrer to maintain a rotation speed of 500 rpm and stir for 30 min to make it evenly dispersed, obtaining a BN suspension;

[0077] (4) Transfer the BN suspension with high dispersion and high solid content to a test tube, centrifuge at 8000 rpm for 5 min, and then carefully collect the BN supernatant. Add 0.1 g of TiO2 nano powder into 30 mL of the BN supernatant and stir for 30 min to obtain a uniformly transparent TiO2 / BN solution (with a volume of about 30 mL);

[0078] (5) Weigh 0.1 g of PVP and slowly add it into the TiO2 / BN solution in step (4), and stir for 8 h to obtain a TiO2 / BN (the molar ratio of TiO2 / BN is 1:30) hydrogel.

[0079] Example 5

[0080] A preparation method of a TiO2 / BN hydrogel with high solid content and high catalytic efficiency is as follows:

[0081] (1) Add 3 g of BN powder into a ball milling jar with a capacity of 50 mL, and then add 40 mL of absolute ethanol as a buffer solution. Set the rotation speed to 300 rpm and ball mill for 12 h;

[0082] (2) Place the ball-milled BN slurry in an oven at 60 °C and dry for 8 h. Thoroughly grind the obtained white BN powder and sieve it through a 60-mesh sieve to obtain the preliminary BN powder;

[0083] (3) Add 30 mg of the obtained BN powder into a mixed solution of 20 mL of deionized water and ethanol (the volume ratio of deionized water to absolute ethanol is 1:1). Use a magnetic stirrer to maintain a rotation speed of 500 rpm and stir for 30 min to make it evenly dispersed, obtaining a BN suspension;

[0084] (4) Transfer the BN suspension with high dispersion and high solid content to a test tube, centrifuge it at 8000 rpm for 5 min, and then carefully collect the BN supernatant; add 0.1 g of TiO2 nano powder to 30 mL of the BN supernatant, stir for 30 min to obtain a uniformly transparent TiO2 / BN solution (with a volume of about 30 mL);

[0085] (5) Weigh 0.1 g of PVP, slowly add it to the TiO2 / BN solution in step (2), and stir for 8 h to obtain a TiO2 / BN (TiO2 / BN molar ratio is 1:30) hydrogel.

[0086] Example 6

[0087] A preparation method of TiO2 / BN hydrogel with high solid content and high catalytic efficiency is as follows:

[0088] (1) Add 3 g of BN powder to a ball mill jar with a capacity of 50 mL, and then add 30 mL of absolute ethanol as a buffer solution. Set the rotation speed to 300 rpm and ball mill for 12 h;

[0089] (2) Place the ball-milled BN slurry in an oven at 60 °C and dry for 8 h. Thoroughly grind the obtained white BN powder, sieve it through a 60-mesh sieve to obtain the preliminary BN powder;

[0090] (3) Add 30 mg of the obtained BN powder to a mixed solution of 30 mL of deionized water and ethanol (the volume ratio of deionized water to absolute ethanol is 1:1), use a magnetic stirrer, keep the rotation speed at 500 rpm, stir for 30 min to make it disperse evenly, and then perform ultrasonic treatment at 100 W for 1 h to obtain a BN suspension with high dispersion and high solid content;

[0091] (4) Transfer the BN suspension with high dispersion and high solid content to a test tube, centrifuge it at 8000 rpm for 5 min, and then carefully collect the BN supernatant; add 0.1 g of TiO2 nano powder to 30 mL of the BN supernatant, stir for 30 min to obtain a uniformly transparent TiO2 / BN solution (with a volume of about 30 mL);

[0092] (5) Weigh 0.1 g of PEG, slowly add it to the TiO2 / BN solution in step (4), and stir for 8 h to obtain a TiO2 / BN (TiO2 / BN molar ratio is 1:30) hydrogel.

[0093] Comparative Example 1

[0094] (1) Add 3 g of BN powder to a ball mill jar with a capacity of 50 mL, and then add 30 mL of absolute ethanol as a buffer solution. Set the rotation speed to 300 rpm and ball mill for 12 h;

[0095] (2) Place the ball-milled BN slurry in an oven at 60 °C and dry it for 8 h. Thoroughly grind the obtained white BN powder and sieve it through a 60-mesh sieve to obtain a preliminary BN powder.

[0096] (3) Add 30 mg of the obtained BN powder to a mixed solution of 30 mL of deionized water and ethanol (the volume ratio of deionized water to absolute ethanol is 1:1). Use a magnetic stirrer to maintain a rotation speed of 500 rpm and stir for 30 min to disperse it evenly. Then, assist with ultrasonic treatment at 100 W for 1 h to obtain a BN suspension with high dispersion and high solid content.

[0097] (4) Transfer the dispersion to a test tube and centrifuge it at 8000 rpm for 5 min. Then, carefully collect the BN supernatant.

[0098] (5) Weigh 0.1 g of PVP and slowly add it to the BN supernatant in step (4). Stir for 8 h to obtain a BN hydrogel.

[0099] Comparative Example 2

[0100] (1) Add 0.1 g of TiO2 nanopowder to a mixed solution of 30 mL of deionized water and ethanol (the volume ratio of deionized water to absolute ethanol is 1:1). Use a magnetic stirrer to maintain a rotation speed of 500 rpm and stir for 30 min to disperse it evenly. Stir for 30 min to obtain a uniform and transparent TiO2 solution (volume is about 30 mL).

[0101] (2) Weigh 0.1 g of PVP and slowly add it to the TiO2 solution in step (1). Stir for 8 h to obtain a TiO2 hydrogel.

[0102] Comparative Example 3

[0103] (1) Add 3 g of BN powder to a ball mill jar with a capacity of 50 mL. Then add 30 mL of absolute ethanol as a buffer solution. Set the rotation speed to 300 rpm and ball mill for 12 h.

[0104] (2) Place the ball-milled BN slurry in an oven at 60 °C and dry it for 8 h. Thoroughly grind the obtained white BN powder and sieve it through a 60-mesh sieve to obtain a preliminary BN powder.

[0105] (3) Add 30 mg of the obtained BN powder to a mixed solution of 30 mL of deionized water and ethanol (the volume ratio of deionized water to absolute ethanol is 1:1). Use a magnetic stirrer to maintain a rotation speed of 500 rpm and stir for 30 min to disperse it evenly. Transfer the dispersion to a test tube and centrifuge it at 8000 rpm for 5 min. Then, carefully collect the BN supernatant to obtain a BN hydrogel.

[0106] Comparative Example 4

[0107] 30 mg of BN powder was added to a mixed solution of 30 mL of deionized water and ethanol (the volume ratio of deionized water to absolute ethanol was 1:1). Using a magnetic stirrer, the rotation speed was maintained at 500 rpm and stirred for 30 min to disperse it evenly. Then, it was supplemented with ultrasonic treatment at 100 W for 1 h. The dispersion was transferred to a test tube and centrifuged at 8000 rpm for 5 min. Then, the BN supernatant was carefully collected to obtain the ultrasonically treated BN hydrogel.

[0108] Comparative Example 5

[0109] 30 mg of BN powder was added to a mixed solution of 30 mL of deionized water and ethanol (the volume ratio of deionized water to absolute ethanol was 1:1). Using a magnetic stirrer, the rotation speed was maintained at 500 rpm and stirred for 30 min to disperse it evenly. The dispersion was transferred to a test tube and centrifuged at 8000 rpm for 5 min. Then, the BN supernatant was carefully collected to obtain the BN hydrogel.

[0110] Comparative Example 6

[0111] (1) 3 g of BN powder was added to a ball mill jar with a capacity of 50 mL, and then 30 mL of absolute ethanol was added as a buffer solution. The rotation speed was set at 300 rpm and ball milled for 12 h;

[0112] (2) The ball milled BN slurry was placed in an oven at 60 °C and dried for 8 h. The obtained white BN powder was thoroughly ground and sieved through a 60-mesh sieve to obtain the preliminary BN powder;

[0113] (3) 30 mg of the obtained BN powder was added to a mixed solution of 30 mL of deionized water and ethanol (the volume ratio of deionized water to absolute ethanol was 1:1). Using a magnetic stirrer, the rotation speed was maintained at 500 rpm and stirred for 30 min to disperse it evenly. Then, it was ultrasonically treated at 100 W for 1 h to obtain a highly dispersed and high solid content BN suspension;

[0114] (4) The dispersion was transferred to a test tube and centrifuged at 8000 rpm for 5 min. Then, the BN supernatant was carefully collected. 0.1 g of TiO2 nanopowder was added to 30 mL of the BN supernatant and stirred for 30 min to obtain a uniformly transparent TiO2 / BN (TiO2 / BN molar ratio was 1:30) hydrogel.

[0115] Comparative Example 7

[0116] (1) 3 g of BN powder was added to a ball mill jar with a capacity of 50 mL, and then 30 mL of absolute ethanol was added as a buffer solution. The rotation speed was set at 300 rpm and ball milled for 12 h;

[0117] (2) Place the ball-milled BN slurry in an oven at 60 °C and dry for 8 h. Thoroughly grind the obtained white BN powder and sieve it through a 60-mesh sieve to obtain the preliminary BN powder;

[0118] (3) Add 30 mg of the obtained BN powder to a mixed solution of 30 mL of deionized water and ethanol (the volume ratio of deionized water to absolute ethanol is 1:1). Use a magnetic stirrer, maintain a rotation speed of 500 rpm, stir for 30 min to make it evenly dispersed, and then ultrasonically treat it at 100 W for 1 h to obtain a BN suspension with high dispersion and high solid content;

[0119] (4) Transfer the dispersion to a test tube and centrifuge it at 8000 rpm for 5 min. Then, carefully collect the BN supernatant. Add 0.1 g of TiO2 nanopowder to 30 mL of the BN supernatant and stir for 30 min to obtain a uniformly transparent TiO2 / BN solution (with a volume of approximately 30 mL);

[0120] (5) Weigh 0.01 g of PVP and slowly add it to the TiO2 / BN solution in step (4), stir for 8 h to obtain a TiO2 / BN (TiO2 / BN molar ratio is 1:30) hydrogel.

[0121] Comparative Example 8

[0122] (1) Add 3 g of BN powder to a ball mill pot with a capacity of 50 mL, and then add 30 mL of absolute ethanol as a buffer solution. Set the rotation speed to 300 rpm and ball mill for 12 h;

[0123] (2) Place the ball-milled BN slurry in an oven at 60 °C and dry for 8 h. Thoroughly grind the obtained white BN powder and sieve it through a 60-mesh sieve to obtain the preliminary BN powder;

[0124] (3) Add 30 mg of the obtained BN powder to a mixed solution of 30 mL of deionized water and ethanol (the volume ratio of deionized water to absolute ethanol is 1:1). Use a magnetic stirrer, maintain a rotation speed of 500 rpm, stir for 30 min to make it evenly dispersed, and then ultrasonically treat it at 100 W for 1 h to obtain a BN suspension with high dispersion and high solid content;

[0125] (4) Transfer the dispersion to a test tube and centrifuge it at 8000 rpm for 5 min. Then, carefully collect the BN supernatant. Add 0.1 g of TiO2 nanopowder to 30 mL of the BN supernatant and stir for 30 min to obtain a uniformly transparent TiO2 / BN solution (with a volume of approximately 30 mL);

[0126] (5) Weigh 0.01 g of PEG and slowly add it to the TiO2 / BN solution in step (4), and stir for 8 h to obtain a TiO2 / BN (TiO2 / BN molar ratio is 1:30) hydrosol.

[0127] Comparative Example 9

[0128] (1) Add 3 g of BN powder to a ball milling jar with a capacity of 50 mL, and then add 30 mL of absolute ethanol as a buffer solution. Set the rotation speed to 300 rpm and ball mill for 12 h;

[0129] (2) Place the ball milled BN slurry in an oven at 60 °C and dry for 8 h. Thoroughly grind the obtained white BN powder and sieve it through a 60-mesh sieve to obtain a preliminary BN powder;

[0130] (3) Add 30 mg of the obtained BN powder to a mixed solution of 30 mL of deionized water and ethanol (volume ratio of deionized water to absolute ethanol is 1:1), use a magnetic stirrer, keep the rotation speed at 500 rpm, and stir for 30 min to make it disperse evenly. Then, perform ultrasonic treatment at 100 W for 1 h to obtain a BN suspension with high dispersion and high solid content;

[0131] (4) Transfer the dispersion to a test tube and centrifuge at 8000 rpm for 5 min. Then, carefully collect the BN supernatant. Add 0.1 g of TiO2 nano powder to 30 mL of the BN supernatant and stir for 30 min to obtain a uniformly transparent TiO2 / BN solution (volume is about 30 mL);

[0132] (5) Weigh 0.3 g of PVP and slowly add it to the TiO2 / BN solution in step (4), and stir for 8 h to obtain a TiO2 / BN (TiO2 / BN molar ratio is 1:30) hydrosol.

[0133] Comparative Example 10

[0134] (1) Add 3 g of BN powder to a ball milling jar with a capacity of 50 mL, and then add 30 mL of absolute ethanol as a buffer solution. Set the rotation speed to 300 rpm and ball mill for 12 h;

[0135] (2) Place the ball milled BN slurry in an oven at 60 °C and dry for 8 h. Thoroughly grind the obtained white BN powder and sieve it through a 60-mesh sieve to obtain a preliminary BN powder;

[0136] (3) Add 30 mg of the obtained BN powder into a mixed solution of 30 mL of deionized water and ethanol (the volume ratio of deionized water to absolute ethanol is 1:1). Use a magnetic stirrer to maintain a rotation speed of 500 rpm and stir for 30 min to disperse it evenly. Then, perform ultrasonic treatment at 100 W for 1 h to obtain a BN suspension with high dispersion and high solid content;

[0137] (4) Transfer the dispersion to a test tube and centrifuge it at 8000 rpm for 5 min. Then, carefully collect the BN supernatant. Add 0.1 g of TiO2 nanopowder into 30 mL of the BN supernatant and stir for 30 min to obtain a uniformly transparent TiO2 / BN solution (with a volume of about 30 mL);

[0138] (5) Weigh 0.3 g of PEG and slowly add it into the TiO2 / BN solution in step (4), and stir for 8 h to obtain a TiO2 / BN (the molar ratio of TiO2 / BN is 1:30) hydrogel.

[0139] Experimental Example

[0140] Conduct the following analysis experiments on the materials of Examples 1-6 and Comparative Examples 1-10:

[0141] 1. Particle size analysis: Figure 1 (a) is the bar chart of the particle size distribution of the BN hydrogel prepared in Comparative Example 4, and (b) is the bar chart of the particle size distribution of the BN hydrogel in step (4) of Example 1. It can be seen from Figure 1 (a) that the particle size distribution of the BN particles without ball milling and ultrasonic treatment is relatively dispersed (0.05 - 45 μm), 39.28% of the BN particles have a particle size distribution in the range of 2 - 5 μm, and 15.14% of the BN particles have a particle size above 10 μm. It can be seen from Figure 1 (b) that the particle size distribution of the BN particles in the BN hydrogel prepared in Example 1 is concentrated in the range of 0.5 - 2 μm, and 84.2% of the BN particles have a particle size distribution in the range of 0.8 - 1.5 μm. The bar chart of the particle size distribution shows that after the BN particles are treated by the ball milling and ultrasonic method, the particle size is significantly reduced, which indicates that this treatment method effectively breaks the particles, increases their specific surface area, and thus improves their reaction activity and efficiency in applications such as catalysis and adsorption. In addition, the reduction of the particle size also helps to improve the dispersibility and uniformity of the material.

[0142] 2. Solid content test: Prepare four centrifuge tubes, weigh and record the weight of the centrifuge tubes. Transfer the BN hydrogel in step (4) of Example 1 and the BN hydrogels prepared in Comparative Examples 3-5 into the centrifuge tubes with known mass, and place them in a vacuum drying oven at 60 °C for vacuum drying for 12 h. Then weigh and record the mass of the centrifuge tubes after vacuum drying. According to the formula Obtain the solid content of the BN hydrogel, as Figure 2 shown. Where G is the solid content of the hydrogel, in mg / ml; m1 is the mass of the centrifuge tube, m2 is the mass of the centrifuge tube after vacuum drying, in g; v is the volume of the hydrogel, in mL.

[0143] From Figure 2 it can be seen that for the BN hydrogel without any treatment in Comparative Example 5, the solid content is the lowest, which is 0.063 mg / mL. The solid content of the BN hydrogel treated by ball milling and ultrasonic treatment in Example 1 is the highest, which is 0.107 mg / mL. After ball milling and ultrasonic treatment, the solid content of the BN hydrogel has increased by 70%. Further analysis shows that ball milling and ultrasonic treatment significantly improve the dispersibility and stability of the BN hydrogel. This may be related to the decrease in the size of BN particles and the increase in surface energy during the treatment process, thus promoting its uniform distribution in the aqueous phase. In addition, the increase in the solid content not only reflects the increase in the effective addition amount of BN, but also means better dispersibility in the hydrogel, which helps to improve the performance in subsequent applications.

[0144] 3. XRD test: Figure 3 are the XRD patterns of the TiO2 / BN hydrogel prepared in Example 1, the BN hydrogel prepared in Comparative Example 1, and the TiO2 hydrogel prepared in Comparative Example 2. The XRD pattern shows that the crystal phase structure of the TiO2 / BN hydrogel is consistent with that of TiO2 in Comparative Example 2, and at the same time, the relevant diffraction peaks of BN can be detected, indicating the successful preparation of the TiO2 / BN hydrogel.

[0145] 4. SEM test and elemental mapping analysis: Use a dropper to suck the TiO2 / BN hydrogel prepared in Example 1, and drop 2 - 3 drops of the TiO2 / BN hydrogel on a conductive glass with an area of 1 cm 2 . Place it in an oven at 40 °C and dry for 7 h to obtain a film material. Adhere the dried conductive glass to the conductive glue with the side coated with the TiO2 / BN hydrogel facing up. After sputtering with gold, perform SEM and EDS tests on the film material. Figure 4 are the SEM pictures of the TiO2 / BN hydrogel prepared in Example 1. (a) is the SEM picture of the TiO2 / BN hydrogel magnified 20,000 times, and (b) is the SEM picture of the TiO2 / BN hydrogel magnified 50,000 times. From Figure 4 it can be seen that the TiO2 nanoparticles are about 5 nm in size, with a small particle size, and are evenly attached to the BN nanosheets, increasing the active sites for the photocatalytic reaction. Figure 5 a is the SEM picture of the TiO2 / BN hydrogel prepared in Example 1. Figure 5 b is the EDS energy spectrum of the TiO2 / BN hydrogel prepared in Example 1. Figure 5 c, Figure 5d is the elemental mapping diagram of the TiO2 / BN hydrosol prepared in Example 1. The EDS spectrum proves the existence of various elements in the sample, and the elemental mapping diagram further proves the uniform distribution of various elements in the TiO2 / BN hydrosol.

[0146] 5. TEM test: Figure 6 a is the TEM image of the BN hydrosol prepared in Comparative Example 1. Figure 6 b is the TEM image of the TiO2 / BN hydrosol prepared in Example 1. It can be seen from the Figure 6 comparison that the incorporation of TiO2 makes the originally smooth surface of the BN nanosheets uneven, increasing the specific surface area of the material and providing more active sites.

[0147] 6. HRTEM test: Figure 7 is the HRTEM image of the TiO2 / BN hydrosol prepared in Example 1. The interplanar spacings of the selected regions are 0.171 nm and 0.216 nm, corresponding to the (105) crystal plane of TiO2 and the (100) crystal plane of BN respectively. This indicates that the grain boundary interaction during the formation of the TiO2 / BN hydrosol promotes the good combination of the two materials.

[0148] 7. UV-Vis DRS analysis: The results of the diffuse reflectance absorption spectrum UV-Vis DRS analysis of Example 1 and Comparative Examples 1-2 are as Figure 8 shown. The results show that the BN hydrosol and TiO2 hydrosol prepared in Comparative Examples 1-2 have light absorption only in the ultraviolet region and no light absorption in the visible region. The TiO2 / BN hydrosol prepared in Example 1 has light absorption in both the ultraviolet region and the visible region. This indicates that the optical properties of the TiO2 / BN hydrosol give it significant advantages in the conversion and utilization of light energy. By introducing BN, the light absorption range of the hydrosol is extended, and more solar energy can be effectively captured, thereby improving the efficiency of the photocatalytic reaction.

[0149] 8. Photocurrent analysis: The photocurrent analysis of the materials in Examples 1-3 and Comparative Examples 1-2 is carried out, and the results are as Figure 9 shown. The TiO2 / BN hydrosol prepared in Example 1 has the strongest photocurrent response ability. This indicates that the TiO2 / BN hydrosol can effectively generate more photoinduced electrons under illumination, showing excellent photocurrent response performance, and can quickly and effectively convert light energy into electrical energy, promoting the reaction rate in the photocatalytic process, thereby improving the overall reaction efficiency.

[0150] 9. AC impedance analysis: The impedance analysis of the materials in Examples 1-3 and Comparative Examples 1-2 is carried out, and the results are as Figure 10 shown. The size of the arc reflects the electron transport ability of the photocatalyst. The smaller the radius, the easier the electrons are to transport. From Figure 10It can be seen that the TiO2 / BN hydrosol prepared in Example 1 has the minimum impedance and the maximum electron transport ability. Compared with the hydrosols prepared in Comparative Examples 1-2, the structure of this composite hydrosol can reduce the energy loss of electrons during migration, further optimizing the kinetics of the photocatalytic reaction. This enhanced electron transport ability not only increases the reaction rate of the photocatalyst but also helps to improve the stability and efficiency of the photocatalytic process.

[0151] Application Experimental Example 1:

[0152] Photocatalytic degradation of Rhodamine B (RhB)

[0153] The hydrosols prepared in Examples 1-6 and Comparative Examples 1-2, 6-10 were applied to the photocatalytic degradation of Rhodamine B (RhB) solution. The concentration of the Rhodamine B (RhB) solution was 20 mg / L. The specific steps are as follows:

[0154] Photocatalytic degradation method: At room temperature, 9 mL of the above different hydrosols was added to 36 mL of Rhodamine B (RhB) solution, and magnetic stirring was carried out in a photoreactor for 30 min to achieve adsorption-desorption equilibrium; an 800 W xenon lamp source was used to simulate standard sunlight, and samples were taken every 5 min for absorbance detection with a UV-2550 spectrophotometer. The results are shown in Table 1 and Figure 11 as follows.

[0155] Table 1 Comparison of degradation rate and degradation time of photocatalytic degradation of RhB by different samples

[0156] Serial number Sample Degradation rate Degradation time 1 Example 1 99.41％ 30min 2 Example 2 90.03％ 30min 3 Example 3 82.97％ 30min 4 Example 4 98.48％ 30min 5 Example 5 97.33％ 30min 6 Example 6 98.65％ 30min 7 Comparative example 1 1.12％ 30min 8 Comparative example 2 3.9％ 30min 9 Comparative example 6 79.11％ 30min 10 Comparative example 7 96.1％ 30min 11 Comparative example 8 95.54％ 30min 12 Comparative example 9 86.5％ 30min 13 Comparative example 10 84.6％ 30min

[0157] It can be seen from Table 1 that within the same degradation time, the TiO2 / BN hydrosol prepared in Example 1 has the largest degradation rate of RhB, which is 99.41%, and the BN hydrosol prepared in Comparative Example 1 has the smallest degradation rate of RhB, which is 1.12%.

[0158] Figure 11 (a) is the RhB degradation diagram of the TiO2 / BN hydrosols prepared in Examples 2-5, the BN hydrosol prepared in Comparative Example 1, and the TiO2 hydrosol prepared in Comparative Example 2. It can be seen from the Figure 11 degradation curve of (a) that the hydrosols prepared in Examples 4-5 have a higher photocatalytic degradation rate, and both the adsorption ability and the photocatalytic degradation ability are superior to those of the hydrosols prepared in Examples 2-3. However, the adsorption ability and the photocatalytic degradation ability of Examples 2-3 are superior to those of Comparative Examples 1-2, and the degradation efficiency of Comparative Examples 1-2 is much lower than that of Examples 2-5. This indicates that the introduction of BN has a significant promoting effect on the photocatalytic ability of TiO2. Figure 11 (b) is the RhB degradation diagram of the TiO2 / BN hydrosols prepared in Example 1, Example 6, and Comparative Examples 6-10. FromFigure 11 It can be clearly observed in (b) that the TiO2 / BN hydrosol prepared in Example 1 exhibits the highest photocatalytic degradation rate, while the TiO2 / BN hydrosol of Comparative Example 6 shows the lowest degradation efficiency. At the same time, the photocatalytic degradation rates of the TiO2 / BN hydrosols prepared in Example 1 and Example 6 are similar, and the photocatalytic degradation rates of Comparative Example 7 and Comparative Example 8 also show similar performances. The degradation rates between Comparative Example 9 and Comparative Example 10 are also close. However, too much or too little PVP and PEG in Comparative Examples 7-10 will reduce the performance of the hydrosol. These results indicate that adding PVP or PEG to the TiO2 / BN hydrosol can significantly improve its photocatalytic degradation rate, and the effects of PVP and PEG on the performance of the hydrosol are similar. The appropriate addition of additives in the TiO2 / BN hydrosol can effectively prevent particle agglomeration, thereby increasing the specific surface area of the catalyst and further enhancing the overall efficiency of the photocatalytic reaction.

Claims

1. Application of TiO2 / BN hydrosol with high solid content and high catalytic efficiency, characterized in that, For the catalytic degradation of rhodamine B aqueous solution under ultraviolet-visible light, the volume ratio of TiO2 / BN sol to rhodamine B aqueous solution is (5-20):(20-80); The TiO2 / BN sol with high solid content and high catalytic efficiency is prepared by the following method: (1) Add BN powder into a ball milling tank, add absolute ethanol as a buffer solution, ball mill for 10-12 h to obtain a BN slurry. Dry the BN slurry, grind it thoroughly, and sieve it to obtain preliminary BN powder; the mass-volume ratio of BN powder to absolute ethanol is (1-5):(10-50), unit g / mL. The ball milling is carried out using steel balls with a diameter of 3-6 mm, the ball milling speed is 200-400 rpm, and the ball milling operation program is: work for 20-40 min, rest for 8-12 min. Drying is carried out at 50-70 °C for 6-10 h, and sieving is through a 60-mesh sieve; (2) Add the preliminary BN powder into a mixed solution of deionized water and ethanol, stir to disperse it evenly, and perform ultrasonic treatment to obtain a high-solid-content BN suspension; the mass-volume ratio of BN powder to the mixed solution is (0.01-0.3):(10-300), unit g / mL. The volume ratio of deionized water to absolute ethanol in the mixed solution of deionized water and ethanol is 1:

1. The ultrasonic treatment is carried out at 50-200 W for 0.5-2 h; (3) Centrifuge the BN suspension and collect the BN supernatant; (4) Mix TiO2 nanopowder in the BN supernatant and stir to obtain a uniformly transparent TiO2 / BN solution; the mass-volume ratio of TiO2 nanopowder to the BN supernatant is (0.05-1):(15-300), unit g / mL, and the mass ratio of TiO2 nanopowder to the dissolved BN in the supernatant is (0.05-1):(0.0015-0.3); (5) Slowly add polyvinylpyrrolidone (PVP) or polyethylene glycol (PEG) to the TiO2 / BN solution and stir for 6-8 h to obtain TiO2 / BN sol; PVP is K90 polyvinylpyrrolidone with a weight-average molecular weight of 1.3 million, the average molecular weight of PEG is 2000, and the mass-volume ratio of PVP or PEG to the TiO2 / BN solution is (0.05-0.2):(15-60), unit g / mL.

2. The application according to claim 1, characterized in that, In step (3), centrifugation is carried out at 7000-9000 rpm for 4-10 min.

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