A core-shell snowman-like janus composite material, and a preparation process and application thereof

Abstract

The present application relates to the technical field of functional materials, in particular to a kind of core-shell snowman Janus composite material and its preparation process and application, the method is first by light initiation seed swelling polymerization method preparation with epoxy / pyridine group chemical anisotropy snowman Janus microspheres, after amino modification, using amino hydrolysis condensation and pyridine nitrogen coordination effect makes titanium dioxide uniform deposition on surface, again by high-temperature carbonization and water vapor activation, with Janus carbon as core, defect anatase TiO2 As shell of core-shell composite material.This material has high specific surface area adsorption performance and photocatalytic activity, can efficiently remove dye pollutants in wastewater, and excellent cycle stability.

Description

Technical Field

[0001] This invention relates to the field of functional materials technology, specifically to a core-shell type snowman-shaped Janus composite material, its preparation process, and its applications. Background Technology

[0002] The printing, textile, and paper industries release large amounts of organic pollutants, such as toxic dyes, during their production processes. These pollutants inevitably enter water bodies, causing water pollution and posing a serious threat to human health. Dye wastewater is characterized by its deep color, high content of organic pollutants, and reluctance to degrade. Significant changes in water quality can disrupt the stability of aquatic ecosystems, interfere with normal material cycling and energy flow in water bodies, and some dyes and their degradation products may possess carcinogenic, teratogenic, and mutagenic toxicity. Advanced oxidation processes (AOPs) are widely considered a highly efficient water treatment technology capable of effectively degrading organic pollutants in water by generating reactive free radicals. Photocatalysis, as a clean advanced oxidation technology, has attracted widespread attention in the water treatment field due to its ability to efficiently utilize solar energy to decompose organic pollutants.

[0003] Titanium dioxide (TiO2) nanoparticles are considered ideal photocatalysts for solving organic pollution problems due to their low cost, non-toxicity, high efficiency, and excellent chemical stability. However, there are two main problems with the practical application of nano-TiO2 photocatalysts: (1) Nano-TiO2 has a wide band gap (about 3.2 eV), a fast photogenerated electron-hole recombination rate, and inherent easy aggregation characteristics, which limit its utilization of solar energy and photocatalytic activity; (2) TiO2 powder photocatalysts are difficult to separate, recover, and reuse in actual water treatment, which hinders their practical application and poses a risk of secondary pollution to the environment. In addition, the adsorption of organic matter on the TiO2 surface is the rate-controlling step of photocatalytic degradation kinetics, but the adsorption capacity of TiO2 powder itself is small, which seriously affects the degradation performance. Therefore, it is urgent to develop a new composite system to break through the application bottleneck of TiO2 photocatalysis and improve its practical water treatment efficiency.

[0004] To address these issues, researchers have explored various modification strategies. One strategy involves loading TiO2 onto various support materials to reduce TiO2 aggregation and increase surface active sites. Another strategy is to construct core-shell composite materials, assembling TiO2 and functional components in a spatially uniform and ordered manner to achieve synergistic effects between the core and shell components, thereby improving photocatalytic efficiency. However, traditional support materials are often structurally simple and lack functionality, making it difficult to simultaneously meet the synergistic requirements of high adsorption performance and efficient photocatalytic activity.

[0005] In recent years, Janus particles—colloidal particles with different chemical compositions or properties on both sides—have attracted attention due to their unique chemical anisotropy. The Janus structure can effectively promote charge separation, thus exhibiting excellent photocatalytic performance potential. Previous studies have shown that Janus-based catalysts can improve degradation efficiency by 1.5 to 10 times compared to non-Janus core-shell catalysts. However, the preparation of TiO2 / Janus composites still faces the following technical challenges: First, the uniformity of TiO2 coating on the Janus particle surface is difficult to control, easily leading to localized excessive thickness or exposure, resulting in unstable catalytic performance; second, the interfacial bonding strength between the TiO2 shell and the Janus core is insufficient, making shell detachment prone to occur during recycling; third, the TiO2 / Janus composites prepared by existing methods have limited specific surface area and low adsorption capacity, making it difficult to fully utilize the synergistic effect of adsorption-catalysis. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a core-shell snowman-shaped Janus composite material, its preparation process, and its applications. The invention utilizes polyglycidyl methacrylate microspheres as seeds, employing a photo-initiated seed swelling polymerization method to prepare snowman-shaped Janus microspheres with chemical anisotropy between epoxy and pyridine groups. Further, the head epoxy groups are converted to amino groups via an epoxy-amine reaction. The hydrolysis and condensation reaction of the amino group with tetrabutyl titanate, along with the coordination reaction between nitrogen and titanium atoms in the pyridine ring, achieves uniform deposition of TiO2 on the entire surface of the snowman-shaped Janus particles. Finally, high-temperature calcination carbonizes the core to form Janus carbon, while simultaneously using steam activation to create pores and retain the TiO2 shell. The prepared core-shell snowman-shaped Janus composite material combines the high specific surface area adsorption performance of the Janus carbon core with the photocatalytic activity of the TiO2 shell, effectively overcoming the defects of traditional TiO2 photocatalysts such as easy aggregation, difficulty in recovery, and poor adsorption capacity. It has broad application prospects in the adsorption and photocatalytic degradation of dye pollutants.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A method for preparing a core-shell type snowman-shaped Janus composite material includes the following steps: After activating the poly(glycidyl methacrylate) microsphere seeds, they were mixed with an organic phase containing 4-vinylpyridine, divinylbenzene, dodecyl alcohol and cyclohexanol and an aqueous phase containing sodium dodecyl sulfate and polyvinyl alcohol to form an emulsion. A photoinitiator was added, and the polymerization reaction was initiated by swelling and ultraviolet light irradiation to obtain snowman-shaped Janus microspheres.

[0008] The snowman-shaped Janus microspheres were reacted with ethylenediamine to convert the epoxy groups at the head into amino groups, thus obtaining amino-modified snowman-shaped Janus microspheres.

[0009] The amino-modified snowman-shaped Janus microspheres were then dispersed in an aqueous solution containing sodium dodecyl sulfate. Anhydrous ethanol, isopropanol, and tetrabutyl titanate were added and stirred. Through the hydrolysis and condensation reaction of amino groups with tetrabutyl titanate and the coordination reaction between nitrogen atoms in the pyridine ring and titanium atoms, titanium dioxide was deposited in situ on the surface of the microspheres. After washing and drying, core-shell snowman-shaped Janus composite microspheres were obtained.

[0010] The core-shell snowman-shaped Janus composite microspheres were first pre-carbonized by heating in an air atmosphere, and then activated by heating in a nitrogen atmosphere and introducing water vapor, so that the core was carbonized to form disordered porous carbon, while the titanium dioxide shell was retained, thus obtaining the core-shell snowman-shaped Janus composite material.

[0011] In a preferred embodiment of the present invention, the polymer skeleton is first heated to 300-500°C at a heating rate of 1-5°C / min in an air atmosphere and held for 5-8 hours to pre-carbonize the polymer skeleton. Then, the temperature is raised to 400-800°C at a heating rate of 1-5°C / min in a N2 atmosphere, and water vapor is introduced for activation treatment to increase the surface area and pore size of the material.

[0012] In a preferred embodiment of the present invention, the mass ratio of the polyglycidyl methacrylate seeds to the oil phase containing 4-vinylpyridine, divinylbenzene, dodecyl alcohol and cyclohexanol, and the aqueous phase containing sodium dodecyl sulfate and polyvinyl alcohol is 1~5:10~20:30~60; in the oil phase, 4-vinylpyridine accounts for 30~40%, divinylbenzene accounts for 15~25%, dodecyl alcohol accounts for 20~35%, and cyclohexanol accounts for 5~20%, totaling 100%; in the aqueous phase, sodium dodecyl sulfate accounts for 0.1~2%, polyvinyl alcohol accounts for 3~10%, and the remainder is water, totaling 100%.

[0013] In a preferred embodiment of the present invention, the particle size of the polyglycidyl methacrylate microspheres is 0.2 μm to 3.0 μm; the amount of anhydrous ethanol is 5.0 to 20 mL; the amount of isopropanol is 0.2 to 2.0 mL; the amount of tetrabutyl titanate is 0.1 to 2.0 mL; the stirring rate is 80 to 150 rpm; the ratio of the amino-modified snowman-shaped Janus microspheres to the aqueous solution of sodium dodecyl sulfate is 2:10 to 30; the temperature of the hydrolysis-condensation reaction is 25 to 30 °C, and the reaction time is 10 to 30 min; the reaction temperature of the coordination reaction is 60 to 80 °C, and the reaction time is 5 to 8 h.

[0014] Another objective is to obtain a core-shell type snowman-shaped Janus composite material by the aforementioned preparation method.

[0015] In a preferred embodiment of the present invention, the shell of the core-shell type snowman-shaped Janus composite material has a snowman-like morphology, consisting of two spheres of different sizes bonded together, one for the head and one for the body; the core is Janus carbon, and the outer shell is a titanium dioxide layer, forming a clear interface between the shell and the core; the shell is TiO2 with a defective anatase structure; the TiO2 shell with the defective anatase structure is firmly loaded onto the surface of the Janus carbon core through coordination bonds and chemical bonds with the nitrogen atoms in the amino groups of the head and the pyridine rings of the body; the snowman-shaped Janus composite material containing the titanium dioxide shell has a mesoporous structure with a specific surface area ≥177 m². 2 / g, and has a wide range of light absorption capabilities in the ultraviolet-visible band; the pore size of the mesoporous structure is mainly distributed between 2 and 50 nm.

[0016] The composite material described in this invention is used as an adsorbent or photocatalyst for removing dye pollutants from wastewater.

[0017] In a preferred embodiment of the present invention, the dye pollutant is Coomassie Brilliant Blue or Methylene Blue; the composite material provides physical adsorption sites through its disordered porous carbon core and provides photocatalytic active centers through its oxygen-deficient anatase titanium dioxide shell, thereby achieving a synergistic removal effect of adsorption enrichment and photocatalytic degradation.

[0018] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention provides a method for preparing a core-shell type snowman-shaped Janus composite material. The method uses polyglycidyl methacrylate microspheres as seeds, 4-vinylpyridine as a functional monomer, divinylbenzene as a crosslinking agent, and dodecyl alcohol and cyclohexanol as dual-template pore-forming agents. A photo-initiated seed swelling polymerization method is used to prepare snowman-shaped Janus microspheres with chemical anisotropy between epoxy groups and pyridine groups. The head epoxy groups are modified to amino groups through an epoxy-amine reaction. The uniform and firm deposition of TiO2 on the entire surface of the snowman-shaped Janus particles is achieved by utilizing the hydrolysis and condensation reaction of the amino group with tetrabutyl titanate and the coordination reaction between nitrogen atoms in the pyridine ring and titanium atoms. This avoids the problem of uneven shell layer or detachment caused by the lack of chemical anchoring points in traditional TiO2 coating methods. Finally, high-temperature calcination carbonizes the core to form Janus carbon, while retaining the TiO2 shell layer. Steam activation is used to further increase the specific surface area. The preparation method is simple, easy to implement, and under mild conditions, making it suitable for industrial production.

[0019] 2. The core-shell, snowman-shaped Janus composite material prepared in this invention effectively solves the problems of easy aggregation and rapid photogenerated electron-hole recombination rate in traditional TiO2 photocatalysts. By anchoring TiO2 in the form of a shell on the surface of the snowman-shaped Janus microspheres, the TiO2 nanoparticles are spatially separated, avoiding self-aggregation. Simultaneously, the Janus carbon core acts as an electron acceptor, effectively capturing and transferring TiO2 photogenerated electrons, inhibiting the recombination of photogenerated electron-hole pairs, and significantly improving the quantum efficiency. Furthermore, the asymmetric structure of the Janus particles further promotes the spatial separation and migration of charges, enhancing photocatalytic activity.

[0020] 3. The core-shell snowman-shaped Janus composite material prepared by this invention possesses both high specific surface area adsorption performance and photocatalytic degradation performance. On the one hand, after high-temperature carbonization and steam activation, the Janus carbon core forms a disordered carbon structure and abundant mesopores (2~50 nm), with a specific surface area reaching 177 m². 2 With a density of over / g, the TiO2 shell provides numerous adsorption sites, enabling efficient enrichment of dye pollutants. Furthermore, the TiO2 shell retains complete photocatalytic activity, allowing for efficient degradation of adsorbed and enriched pollutants under light conditions. This synergistic effect of adsorption and photocatalysis results in a removal rate of over 95% for dye pollutants such as Coomassie Brilliant Blue, far superior to single-function TiO2 photocatalysts or carbon adsorbents.

[0021] 4. The core-shell snowman-shaped Janus composite material prepared in this invention solves the engineering challenge of separating and recovering traditional TiO2 powder photocatalysts. This material exists in the form of micron-sized (2~5 μm) snowman-shaped particles, which can be rapidly separated and recovered through simple centrifugation or filtration, avoiding secondary pollution of water bodies by TiO2 nanoparticles. Simultaneously, this material exhibits excellent reusability; after five adsorption-photocatalytic cycles, it can still remove more than 95% of Coomassie Brilliant Blue, with the degradation efficiency only slightly decreasing from 89% to 82%, and no Ti component loss was detected, with a weight loss rate of less than 1%, demonstrating excellent cycle stability and practical value.

[0022] 5. The core-shell snowman-shaped Janus composite material prepared by this invention exhibits excellent light absorption capabilities in both the ultraviolet and visible light bands. Unlike pure TiO2, which only responds to ultraviolet light, the presence of the Janus carbon core endows the composite material with visible light response characteristics, effectively broadening the scope of solar energy utilization, improving the utilization rate of sunlight, and reducing the energy consumption cost of water treatment. It has broad application prospects in the field of organic dye pollution treatment such as dyeing and printing wastewater and papermaking wastewater. Attached Figure Description

[0023] Figure 1 This is a schematic diagram illustrating the preparation of core-shell Janus composite materials.

[0024] Figure 2 The images show (a) scanning electron microscopy and (b) particle size distribution of the non-porous polyglycidyl methacrylate microspheres in Example 1.

[0025] Figure 3 (a, b) Scanning electron microscope images of the snowman-shaped Janus microspheres in Example 1.

[0026] Figure 4 The images show (a, b) scanning electron microscope and (c) transmission electron microscope images of polymer@TiO2 in Example 1.

[0027] Figure 5 The images show (a, b) scanning electron microscope (SEM) and transmission electron microscope (TEM) images of C@TiO2-1 in Example 1.

[0028] Figure 6 XPS spectra of snowman-shaped Janus microspheres and polymer@TiO2 particles (a) and high-resolution XPS spectra of Ti 2p (b).

[0029] Figure 7 The infrared spectra of poly(glycidyl methacrylate) microspheres, snowman-shaped Janus microspheres, and polymer@TiO2 in Example 1 (a) are shown.

[0030] Figure 8 The N2 adsorption / desorption curves of polymer@TiO2 in Example 1 are shown.

[0031] Figure 9 The image shows the UV-Vis diffuse reflectance spectrum of C@TiO2-1 in Example 1.

[0032] Figure 10 The image shows the dynamic adsorption curve of C@TiO2-1 for Coomassie Brilliant Blue in Example 1.

[0033] Figure 11 The image shows (a) the photocatalytic degradation of Coomassie Brilliant Blue by C@TiO2-1 in Example 1 and (b) the pseudo-first-order kinetic curve.

[0034] Figure 12 The graph shows the adsorption and degradation efficiency of C@TiO2-1 after five cycles in Example 1.

[0035] Figure 13 The image shows a scanning electron microscope image of C@TiO2-2 in Example 2.

[0036] Figure 14 The N2 adsorption / desorption curves of C@TiO2-2 in Example 2 are shown.

[0037] Figure 15The image shows the UV-Vis diffuse reflectance spectrum of C@TiO2-2 in Example 2.

[0038] Figure 16 The image shows the dynamic adsorption curve of C@TiO2-2 for Coomassie Brilliant Blue in Example 2.

[0039] Figure 17 The image shows (a) the photocatalytic degradation of Coomassie Brilliant Blue by C@TiO2-2 in Example 2 and (b) the pseudo-first-order kinetic curve.

[0040] Figure 18 The image shows a scanning electron microscope image of C@TiO2-3 in Example 3.

[0041] Figure 19 The N2 adsorption / desorption curves of C@TiO2-3 in Example 3 are shown.

[0042] Figure 20 The image shows the UV-Vis diffuse reflectance spectrum of C@TiO2-3 in Example 3.

[0043] Figure 21 The image shows the dynamic adsorption curve of C@TiO2-3 for Coomassie Brilliant Blue in Example 3.

[0044] Figure 22 The image shows (a) the photocatalytic degradation of Coomassie Brilliant Blue by C@TiO2-3 in Example 3 and (b) its pseudo-first-order kinetic curve.

[0045] Figure 23 The images are (a, b) scanning electron microscope (SEM) images of C@TiO2-4 in Comparative Example 1.

[0046] Figure 24 The images are (a, b) scanning electron microscope (SEM) images of C@TiO2-5 in Comparative Example 2.

[0047] Figure 25 The images are (a, b) scanning electron microscope (SEM) images of C@TiO2-6 in Comparative Example 3.

[0048] Figure 26 The N2 adsorption / desorption curves are for C@TiO2-6 in Comparative Example 3.

[0049] Figure 27 The dynamic adsorption curve of C@TiO2-6 for Coomassie Brilliant Blue in Comparative Example 3 is shown.

[0050] Figure 28 The images are (a, b) scanning electron microscope (SEM) images of Janus-carbon in Comparative Example 4.

[0051] Figure 29 The image shows the dynamic adsorption curve of Coomassie Brilliant Blue by Janus-carbon in Comparative Example 4.

[0052] Figure 30 The image shows the photocatalytic degradation of Coomassie Bright Blue by Janus-carbon in Comparative Example 4. Detailed Implementation

[0053] The following detailed description, in conjunction with embodiments of the present invention and accompanying drawings, provides a clear and complete illustration of the technical solutions in these embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0054] It should be noted that all technical terms used in this invention are for the purpose of describing specific embodiments only and are not intended to limit the scope of protection of this invention. Unless otherwise specified, all raw materials, reagents, instruments and equipment used in the following embodiments of this invention can be purchased from the market or prepared by existing methods.

[0055] Example 1: Preparation of core-shell snowman-shaped Janus composite material and its application in dye adsorption and photocatalytic degradation.

[0056] (1) Preparation process of snowman-shaped Janus microspheres: Preparation of self-made polyglycidyl methacrylate microspheres (particle size range 1.7–2 μm): First, 2.0 g of polyvinylpyrrolidone was weighed and added to a pear-shaped flask; then 100 mL of anhydrous ethanol was measured and ultrasonically mixed until homogeneous; subsequently, 10 mL of glycidyl methacrylate and 0.25 g of azobisisobutyronitrile were weighed and added to the pear-shaped flask, ultrasonicated for 15 min, and then purged with nitrogen for 30 min. The reaction apparatus was placed in a rotary evaporator, the temperature was set at 70 ℃, the rotation speed at 110 rpm, and the reaction was carried out for 24 h. After centrifugation and washing, the microspheres were freeze-dried under vacuum for 8 h to obtain solid polyglycidyl methacrylate microspheres (particle size range 1.7–2 μm) with smooth and non-porous surfaces.

[0057] Preparation of snowman-shaped Janus microspheres: First, 0.75 g of poly(GMA) seeds were placed in a quartz conical flask, and the flask was placed in a shaking incubator and activated at 25 ℃ and 200 rpm for 30 min. 1.5 mL of 4-VP, 0.8 mL of DVB, 1.0 mL of dodecanol, and 0.5 mL of cyclohexanol were used as the organic phase, and a mixed solution of 10 mL of 0.2% SDS and 5% PVA was used as the aqueous phase. The organic and aqueous phases were mixed. An oil-in-water emulsion was formed under ultrasonic treatment. Next, 3.0 g of DMPA was added to the emulsion, and the emulsion was mixed with the activated seed suspension. The mixture was shaken at 200 rpm for 16 h. Afterward, the mixture was irradiated under UV light for 2 h. The product was centrifuged, washed with water and ethanol respectively, and then freeze-dried under vacuum to obtain snowman-shaped Janus microspheres.

[0058] (2) Preparation process of snowman-shaped Janus microspheres containing TiO2 shell 2.0 g of dried, snowman-shaped Janus microspheres were dispersed in 20 mL of deionized water and sonicated for 15 min. Then, 1 mL of ethylenediamine solution was added, and the mixture was reacted at 70 °C for 6 h. After the reaction, the microspheres were washed by centrifugation with anhydrous ethanol and deionized water, and finally freeze-dried to obtain amino-containing snowman-shaped Janus microspheres. 2.0 g of amino-containing Janus particles and 1.0 g of sodium dodecyl sulfate were dispersed in 20 mL of deionized water. The mixture was placed in a two-necked flask and sonicated for 15 min to ensure complete dispersion. Then, 10 mL of anhydrous ethanol, 1.0 mL of isopropanol, and 1 mL of tetrabutyl titanate were added to a test tube and sonicated for 10 min. The mixture in the test tube was slowly added dropwise to the two-necked flask under mechanical stirring at 150 rpm. The mixture was reacted at 25 °C for 15 min, then the temperature was increased to 70 °C, and the reaction was continued for 6 h. After the reaction was completed, the product was washed by centrifugation with anhydrous ethanol and deionized water, and then freeze-dried to obtain core-shell snowman-shaped Janus microspheres with TiO2 particles deposited on the surface, which were named polymer@TiO2.

[0059] (3) Preparation process of core-shell type snowman-shaped Janus composite material Carbonization: 5.0 g of core-shell snowman-shaped Janus microspheres were placed in a tube furnace and heated to 350 °C at a heating rate of 1.5 °C / min under air atmosphere, held at that temperature for 5 h, and then cooled to 30 °C at a cooling rate of 1.5 °C / min. Activation: Under N2 atmosphere, the temperature was increased to 600 °C at a heating rate of 1.5 °C / min. Simultaneously, water vapor was introduced at a flow rate of 12 mL / min, and the temperature was maintained at 600 °C for 2 h. The resulting core-shell snowman-shaped Janus composite material was named C@TiO2-1.

[0060] Product Application C@TiO2-1 was used as a photocatalyst for the separation and degradation of Coomassie Brilliant Blue. CBB adsorption: C@TiO2 particles were weighed and added to a CBB solution, then shaken. The shaken solution was filtered. The absorbance of the solution was then measured using a UV-Vis spectrophotometer. This process was repeated five times.

[0061] Photocatalytic degradation of CBB: A photocatalyst was added to the CBB solution, and the mixture was shaken in a dark field. After shaking and sampling, the mixture was transferred to a reactor, and the photoreaction was carried out under a xenon lamp. 1 mL of sample was collected every 20 min. The CBB solution was separated from the catalyst using a 0.22 μm filter membrane. The concentration of CBB was determined using a UV spectrophotometer, and this process was repeated five times.

[0062] Example 2: Preparation of a snowman-shaped Janus composite material containing a TiO2 shell and its application in dye adsorption and photocatalytic degradation.

[0063] The carbonization temperature was adjusted to 600 °C during the preparation of C@TiO2-1 in Example 1, and the remaining preparation steps (process and conditions) were the same as in Example 1. The resulting snowman-shaped Janus composite material containing a titanium dioxide shell was named C@TiO2-2.

[0064] Product Application C@TiO2-2 was used as a photocatalyst for the separation and degradation of Coomassie Brilliant Blue, following the same process as in Example 1.

[0065] Example 3: Preparation of a snowman-shaped Janus composite material containing a TiO2 shell and its application in dye adsorption and photocatalytic degradation.

[0066] The carbonization temperature was adjusted to 800 °C during the preparation of C@TiO2-1 in Example 1, while the remaining preparation steps (process and conditions) were the same as in Example 1. The resulting snowman-shaped Janus composite material containing a titanium dioxide shell was named C@TiO2-3.

[0067] The product was applied by using C@TiO2-3 as a photocatalyst for the separation and degradation of Coomassie Brilliant Blue, in the same process as in Example 1.

[0068] Comparative Example 1: Preparation of a snowman-shaped Janus composite material containing a TiO2 shell and its application in dye adsorption and photocatalytic degradation.

[0069] The amount of tetrabutyl titanate fed directly affects the thickness of the shell and the generation of secondary particles.

[0070] In the preparation of polymer@TiO2 in Examples 1, 2, and 3, the tetrabutyl titanate was adjusted to 3 mL, and the remaining steps (process and conditions) were the same as in Examples 1, 2, and 3. The obtained TiO2-modified core-shell Janus microspheres were named C@TiO2-4.

[0071] In Comparative Example 1, C@TiO2-4 could not uniformly coat TiO2, and TiO2 agglomeration was severe, making it impossible to carry out the next step of adsorption and degradation application.

[0072] Comparative Example 2: Preparation of a snowman-shaped Janus composite material containing a TiO2 shell and its application in dye adsorption and photocatalytic degradation.

[0073] Under static conditions, shell growth is limited due to the low diffusion rate of tetrabutyl titanate. However, excessively high stirring rates significantly increase the interfacial area between the organic and aqueous phases, thereby consuming more tetrabutyl titanate, reducing the amount of tetrabutyl titanate available for shell deposition, and leading to the formation of many secondary particles.

[0074] In Examples 1, 2, and 3, the stirring rate was adjusted to 300 rpm during the preparation of polymer@TiO2, and the remaining steps (process and conditions) were the same as in Examples 1, 2, and 3. The obtained TiO2-modified core-shell Janus microspheres were named C@TiO2-5.

[0075] In Comparative Example 1, C@TiO2-5 could not uniformly coat TiO2, and TiO2 agglomeration was severe, making it impossible to carry out further adsorption and degradation applications.

[0076] Comparative Example 3: Preparation of a snowman-shaped Janus composite material containing a TiO2 shell and its application in dye adsorption and photocatalytic degradation.

[0077] In the preparation of C@TiO2 in Examples 1, 2, and 3, water vapor was not used for activation, and the remaining steps (processes and conditions) were the same as in Examples 1, 2, and 3. The obtained TiO2-modified core-shell Janus microspheres were named C@TiO2-6.

[0078] Product Applications: C@TiO2-6 was used as a photocatalyst for the separation and degradation of Coomassie Brilliant Blue, following the same process as in Example 1.

[0079] Comparative Example 4: Preparation of a snowman-shaped Janus composite material without a TiO2 shell and its application in dye adsorption and photocatalytic degradation.

[0080] In Examples 1, 2, and 3, tetrabutyl titanate was not added during the preparation of polymer@TiO2, and the remaining steps (process and conditions) were the same as in Examples 1, 2, and 3. The resulting snowman-shaped Janus composite material was named Janus-carbon.

[0081] Product Application Janus-carbon was used as a photocatalyst for the separation and degradation of Coomassie Brilliant Blue, following the same process as in Example 1.

[0082] Results Analysis Figure 2 The images show (a) scanning electron microscopy (SEM) and (b) particle size distribution of the non-porous polyglycidyl methacrylate (PGM) microspheres in Example 1. The figures show that the self-made PGM microspheres have an average particle size of approximately 1.80 µm, exhibiting good monodispersity and a smooth surface. Figure 3 Images (a) and (b) are scanning electron microscope (SEM) images of the snowman-shaped Janus microspheres from Example 1. The Janus microspheres are snowman-shaped, with a width ranging from 2.3 to 2.5 μm and a height ranging from 3 to 3.3 μm. One end of the microsphere is rough, while the other end has wrinkles and no obvious pore structure. Figure 4 Images (a) and (b) are scanning electron microscope images of polymer@TiO2 in Example 1. The polymer@TiO2 maintains a snowman-like morphology and has a distinct shell structure on its surface. Figure 4 Image c is a transmission electron microscope (TEM) image of polymer@TiO2 in Example 1. The image shows that the snowman-shaped microspheres are coated with a layer of TiO2 particles. Figure 5 Image a is a scanning electron microscope image of C@TiO2-1 in Example 1. The polymer@TiO2 retains its snowman-like morphology after calcination, and... Figure 5 b. Transmission electron microscopy shows that after calcination at 350 °C, the Janus carbon sphere core (white dashed line) and shell (blue dashed line) of C@TiO2-1 particles are clearly defined, with the shell thickness being approximately 189 nm.

[0083] Its chemical composition was studied using XPS. Figure 6 Figure a shows the XPS spectra of Janus particles and polymer@TiO2 particles. It can be seen that the full XPS spectrum of Janus particles only contains O 1s, C 1s, and N 1s peaks, while the polymer@TiO2 particles contain O 1s, C 1s, N 1s, and Ti 2p peaks. Figure 6As shown in Figure b, the high-resolution spectra of the Ti 2p orbitals corresponding to the polymer@TiO2 particles show peaks at 464.1 eV and 458.3 eV, belonging to the 2p1 / 2 orbitals of Ti atoms and the 2p3 / 2 orbitals from the Ti groups of TBT. These results successfully confirm that the Janus microspheres are coated with a TiO2 shell. The C@TiO2-1 particles are formed after calcination of polymer@TiO2. All the original chemical bonds in polymer@TiO2 break, and the organic matter decomposes, ultimately leaving a porous carbon skeleton core and a TiO2 shell, forming a physically hybrid composite material.

[0084] Figure 7 The infrared spectra of polyglycidyl methacrylate microspheres, snowman-shaped Janus microspheres, and polymer@TiO2 in Example 1 (a) are shown. The Janus particle spectrum has a peak value of 1639 cm⁻¹. -1 The peak at 3419 cm corresponds to the tensile vibration of C=C. -1 The peak at 557 cm⁻¹ corresponds to the NH stretching vibration in the 4-VP pyridine ring. (Polymer@TiO₂ spectrum) -1 The peak at 3324 cm corresponds to Ti-N tensile vibration. -1 The peaks at these peaks correspond to the -OH stretching vibrations on the TiO2 surface. These results further demonstrate the successful coating of TiO2 onto Janus microspheres. However, the existence of these coordination bonds is strictly dependent on the chemical structure of the snowman-shaped Janus microsphere template. During subsequent calcination, the Janus microsphere template undergoes thermal decomposition and carbonization at high temperatures, completely removing all organic functional groups and transforming into an amorphous carbon skeleton. At this point, the original N-Ti coordination bonds are irreversibly destroyed, and no new covalent or coordination bonds (such as Ti-C bonds) recognizable by infrared spectroscopy are formed between carbon and TiO2. In the final C@TiO2-1 composite material, the interface between the carbon core and the TiO2 shell is mainly maintained by physical contact and van der Waals forces, without characteristic vibrational absorption.

[0085] The results of nitrogen adsorption / desorption experiments show that, Figure 8 As shown, after high-temperature calcination, the surface area of ​​C@TiO2-1 particles increased to 177 m². 2 / g, with pore sizes mainly distributed between 2 and 50 nm, belonging to a typical mesoporous structure.

[0086] The results of ultraviolet-visible diffuse reflectance spectroscopy indicate that, for example Figure 9 The C@TiO2-1 particles shown exhibit a wide range of absorption in the ultraviolet-visible wavelength range.

[0087] Based on the dynamic adsorption curve ( Figure 10The maximum adsorption capacity of C@TiO2-1 particles was approximately 186 mg / g. Adsorption reached equilibrium after about 60 minutes.

[0088] According to the photocatalytic degradation performance diagram ( Figure 11 In both cases (a) and (b), C@TiO2-1 achieved a removal rate of >95% for Coomassie Brilliant Blue. The photocatalytic degradation process of Coomassie Brilliant Blue followed the Langmuir-Hinshelwood model, and the linear correlation coefficient (R > 0.99) indicated that the photocatalytic degradation process conformed to pseudo-first-order kinetics. The reaction rate constant of C@TiO2-1 was 0.0156 min. -1 C@TiO2-1 exhibits excellent photocatalytic degradation of Coomassie Brilliant Blue.

[0089] Based on five consecutive adsorption cycles and a photodegradation cycle bar chart ( Figure 12 It can be seen that after the fifth cycle, C@TiO2-1 can still remove >95% of Coomassie Brilliant Blue from the solution; in addition, the degradation efficiency of Coomassie Brilliant Blue only showed a moderate decrease from 89% to 82% after 5 cycles, no loss of Ti content was detected, and there was a weight loss rate of <1% after 5 cycles.

[0090] Scanning electron microscopy results show that, Figure 13 As shown, the snowman-like structure of C@TiO2-2 microspheres exhibits slight collapse. In contrast, in Comparative Example 1, the polymer core vaporizes at a calcination temperature of 600 °C.

[0091] Results of nitrogen adsorption / desorption experiments ( Figure 14 This indicates that the specific surface area of ​​C@TiO2-2 is 26.9 m². 2 / g. Compared with Example 1, due to the vaporization of the polymer core, the disappearance of the carbon solid phase resulted in C@TiO2-2 leaving only a titanium dioxide shell, and the specific surface area of ​​C@TiO2-2 was significantly reduced compared to C@TiO2-1.

[0092] The results of ultraviolet-visible diffuse reflectance spectroscopy indicate that, for example Figure 15 The S-TiO2-600 shown only exhibits strong absorption in the ultraviolet region.

[0093] Based on the dynamic adsorption curve ( Figure 16 The maximum adsorption capacity of C@TiO2-2 particles was approximately 62.3 mg / g. Adsorption reached equilibrium after approximately 45 minutes.

[0094] According to the photocatalytic degradation performance diagram ( Figure 17 Compared with Example 1, the reaction rate constant of Example 1 was significantly reduced (0.0027 min). -1This is attributed to the fact that C@TiO2-2 only has a TiO2 shell, and its large band gap limits its light absorption and catalytic efficiency under visible light irradiation, resulting in its low adsorption and photocatalytic performance.

[0095] Scanning electron microscopy results show that, Figure 18 As shown, the snowman-like structure of C@TiO2-3 microspheres exhibited severe collapse and sintered material. Comparing Examples 1 and 2, it can be inferred that the polymer core completely vaporized at 800 °C.

[0096] Results of nitrogen adsorption / desorption experiments ( Figure 19 This indicates that the specific surface area of ​​C@TiO2-3 is 13.3 m². 2 / g. Compared with Examples 1 and 2, due to the vaporization of the polymer core, the disappearance of the carbon solid phase resulted in C@TiO2-3 leaving only a titanium dioxide shell, and the high temperature caused sintering of C@TiO2-3.

[0097] The results of ultraviolet-visible diffuse reflectance spectroscopy indicate that, for example Figure 20 The C@TiO2-3 shown exhibits strong absorption only in the ultraviolet region.

[0098] Comparing Examples 1, 2, and 3, as the calcination temperature continued to rise, the core of the core-shell snowman-shaped Janus composite material gradually carbonized and eventually vaporized, indicating that temperature adjustment would significantly affect the formation of the disordered carbon structure in the core, thereby affecting the specific surface area of ​​the composite material.

[0099] Based on the dynamic adsorption curve ( Figure 21 The maximum adsorption capacity of C@TiO2-2 particles was approximately 57.2 mg / g. Adsorption reached equilibrium after approximately 45 minutes.

[0100] According to the photocatalytic degradation performance diagram ( Figure 22 Compared with implementations 1 and 2, the reaction rate constant of C@TiO2-3 was further reduced (0.0016 min). -1 ).

[0101] Based on the scanning electron microscope image, such as Figure 23 As shown, when the amount of TBT added is 3 mL, the Janus particle phase separation interface is blurred and the particles stick together, with a small number of small particles appearing around the particles.

[0102] like Figure 24 As shown, the core-shell Janus microspheres prepared in Comparative Example 2 were named C@TiO2-5. When the stirring rate was 300 rpm, the Janus particle phase separation interface was completely covered by small particles, the Janus particles were severely adhered to each other, and a large number of small particles appeared around the particles.

[0103] Based on the scanning electron microscope image, such as Figure 25 As shown, when not activated by water vapor, C@TiO2-6 still maintains its complete snowman shape, with no adhesion between particles, and the entire particle is covered by TiO2 particles.

[0104] Results of nitrogen adsorption / desorption experiments ( Figure 26 This indicates that the specific surface area of ​​C@TiO2-5 is 35.3 m². 2 / g. Compared with Examples 1, 2 and 3, since steam activation was not performed, the key step of "pore formation" was missing. The C@TiO2-6 mainly relied on the initial pores formed by pyrolysis, resulting in a lower specific surface area than Example 1, but a higher specific surface area than Examples 2 and 3.

[0105] Based on the dynamic adsorption curve ( Figure 27 The maximum adsorption capacity of C@TiO2-5 particles was approximately 96.4 mg / g. Adsorption reached equilibrium after approximately 90 minutes. Compared with Example 1, the adsorption capacity of C@TiO2-6 was significantly reduced, indicating that the lack of steam activation affects the adsorption performance of the material and further affects the efficiency of dye treatment.

[0106] Based on the scanning electron microscope image, such as Figure 28 As shown, when tetrabutyl titanate is not added, the carbonized Janus-carbon still maintains its complete snowman shape, with no adhesion between particles and no particulate matter adhering to the surface. The particle size changes from about 5 μm in length to about 2.2 μm compared to the original snowman-shaped Janus particles, indicating that the Janus particles have undergone carbonization.

[0107] Based on the dynamic adsorption curve ( Figure 29 The maximum adsorption capacity of Janus-carbon particles was approximately 230.6 mg / g. Adsorption reached equilibrium after approximately 60 minutes. Comparing Examples 1, 2, and 3, Janus-carbon exhibited the highest adsorption capacity, indicating that TiO2 coating reduces the adsorption performance of the snowman-shaped Janus composite material on Coomassie Brilliant Blue.

[0108] According to the photocatalytic degradation performance diagram ( Figure 30 Compared with implementations 1, 2, and 3, after illumination was turned on (0 h), Janus-carbon showed almost no degradation of Coomassie Brilliant Blue, with a degradation efficiency close to 0%. This indicates that the photocatalytic performance of the material is mainly provided by TiO2.

[0109] It should be noted that when numerical ranges are involved in this invention, it should be understood that both endpoints of each numerical range, as well as any value between the two endpoints, can be selected. Since the steps and processes used are the same as in the embodiments, preferred embodiments are described here to avoid redundancy. Although preferred embodiments of the invention have been described, those skilled in the art, once they understand the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of this invention.

[0110] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for preparing a core-shell type snowman-shaped Janus composite material, characterized in that, Includes the following steps: After activating poly(glycidyl methacrylate) microsphere seeds, they were mixed with an organic phase containing 4-vinylpyridine, divinylbenzene, dodecyl alcohol and cyclohexanol and an aqueous phase containing sodium dodecyl sulfate and polyvinyl alcohol to form an emulsion. A photoinitiator was added, and the polymerization reaction was initiated by swelling and ultraviolet light irradiation to obtain snowman-shaped Janus microspheres. The snowman-shaped Janus microspheres were reacted with ethylenediamine to convert the epoxy groups at the head into amino groups, thus obtaining amino-modified snowman-shaped Janus microspheres. The amino-modified snowman-shaped Janus microspheres were then dispersed in an aqueous solution containing sodium dodecyl sulfate. Anhydrous ethanol, isopropanol, and tetrabutyl titanate were added and stirred. Through the hydrolysis and condensation reaction of amino groups with tetrabutyl titanate and the coordination reaction between nitrogen atoms in the pyridine ring and titanium atoms, titanium dioxide was deposited in situ on the surface of the microspheres. After washing and drying, core-shell snowman-shaped Janus composite microspheres were obtained. The core-shell snowman-shaped Janus composite microspheres were first pre-carbonized by heating in an air atmosphere, and then activated by heating in a nitrogen atmosphere and introducing water vapor, so that the core was carbonized to form disordered porous carbon, while the titanium dioxide shell was retained, thus obtaining the core-shell snowman-shaped Janus composite material.

2. The method for preparing the core-shell type snowman-shaped Janus composite material according to claim 1, characterized in that, First, the polymer skeleton is pre-carbonized by heating it to 300-500 ℃ at a heating rate of 1-5 ℃ / min in an air atmosphere and holding it for 5-8 h. Then, it is heated to 400-800 ℃ at a heating rate of 1-5 ℃ / min in a N2 atmosphere and activated by introducing water vapor to increase the surface area and pore size of the material.

3. The method for preparing the core-shell type snowman-shaped Janus composite material according to claim 1, characterized in that, The mass ratio of the poly(glycidyl methacrylate) seeds to the oil phase containing 4-vinylpyridine, divinylbenzene, dodecyl alcohol, and cyclohexanol, and the aqueous phase containing sodium dodecyl sulfate and polyvinyl alcohol is 1-5:10-20:30-60. In the oil phase, 4-vinylpyridine accounts for 30-40%, divinylbenzene for 15-25%, dodecyl alcohol for 20-35%, and cyclohexanol for 5-20%, totaling 100%. In the aqueous phase, sodium dodecyl sulfate accounts for 0.1-2%, polyvinyl alcohol for 3-10%, and the remainder is water, totaling 100%.

4. The method for preparing the core-shell type snowman-shaped Janus composite material according to claim 1, characterized in that, The particle size of the poly(glycidyl methacrylate) microspheres is 0.2 μm to 3.0 μm; the amount of anhydrous ethanol used is 5.0 to 20 mL; the amount of isopropanol used is 0.2 to 2.0 mL; the amount of tetrabutyl titanate used is 0.1 to 2.0 mL; the stirring rate is 80 to 150 rpm; the ratio of the amino-modified snowman-shaped Janus microspheres to the aqueous solution of sodium dodecyl sulfate is 2:10 to 30; the temperature of the hydrolysis-condensation reaction is 25 to 30 °C, and the reaction time is 10 to 30 min; the reaction temperature of the coordination reaction is 60 to 80 °C, and the reaction time is 5 to 8 h.

5. A core-shell type snowman-shaped Janus composite material prepared by the preparation method according to any one of claims 1-4.

6. The core-shell type snowman-shaped Janus composite material according to claim 5, characterized in that: The core-shell type snowman-shaped Janus composite material has a snowman-like shell, consisting of two spheres of different sizes bonded together, representing the head and body. The core is Janus carbon, and the outer shell is a titanium dioxide layer, forming a clear interface between the shell and the core. The shell is TiO2 with a defective anatase structure. The TiO2 shell with the defective anatase structure is firmly supported on the Janus carbon core surface through coordination and chemical bonding with the nitrogen atoms in the amino groups of the core head and the pyridine rings of the body. The snowman-shaped Janus composite material containing the titanium dioxide shell has a mesoporous structure with a specific surface area ≥177 m². 2 / g, and has a wide range of light absorption capabilities in the ultraviolet-visible band; the pore size of the mesoporous structure is mainly distributed between 2 and 50 nm.

7. The application of the composite material according to claim 5 in the removal of dye pollutants from wastewater as an adsorbent or photocatalyst.

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