A method for preparing and applying a Ti3C2-MXene / TiO2 Schottky heterojunction fiber photocatalyst

Abstract

The application discloses a preparation method and application of a Ti3C2-MXene / TiO2 Schottky heterojunction fiber photocatalyst, develops an alkalization / delocalization process to treat a Ti3C2-MXene colloidal solution, then converts the two-dimensional Ti3C2-MXene colloidal solution into a one-dimensional fiber structure through a wet spinning technology, and finally obtains the Ti3C2-MXene / TiO2 composite fiber material through calcination in a tube furnace. The catalyst is a visible light catalyst with novel structure and excellent catalytic performance, has good light degradation capacity on organic pollutants under visible light, and has a stable fiber structure, and has the properties of recyclability and reusability when applied in water. Meanwhile, the catalyst has the characteristics of simple preparation process, environmental friendliness, high efficiency, energy saving, environmental protection, low cost, safety and the like, is suitable for large-scale production and preparation, and has a good application prospect in the fields of sewage treatment and waste gas treatment.

Description

Technical Field

[0001] This invention relates to a method for preparing a visible light catalyst, specifically to a method for preparing and applying a Ti3C2-MXene / TiO2 Schottky heterojunction fiber photocatalyst; it belongs to the field of novel functional material preparation technology. Background Technology

[0002] With the rapid development of industry and urbanization, the consumption of fossil fuels and water pollution have become increasingly prominent. In particular, organic dyes in the aquatic environment seriously endanger the ecological balance and human health. Rhodamine B (RhB) is the most typical organic pollutant, which is carcinogenic and difficult to degrade into non-toxic and harmless substances under normal conditions. Studies have shown that photocatalytic degradation is one of the most promising technologies for removing organic dyes and their derivatives.

[0003] In recent years, many photocatalysts have been reported in the field of pollutant degradation, such as TiO2, SnO2, CdS, and g-C3N4. Among these photocatalysts, titanium dioxide (TiO2) has become one of the most widely used photocatalysts due to its stable chemical properties, high photocatalytic efficiency, environmental friendliness, and low cost. However, the practical application of single TiO2 in photocatalysis is still greatly limited, mainly due to its large band gap, high photogenerated carrier recombination rate, and low quantum efficiency. To address these issues, a series of strategies can be employed to optimize catalyst performance, such as doping with noble metals or combining it with other narrow-bandgap semiconductors, metal oxides, and carbon materials. However, due to the high cost of noble metals and the complexity of their combination with other semiconductor materials, exploring a co-catalyst without noble metals is of great significance for improving future research in the field of photocatalytic degradation.

[0004] In recent years, a novel two-dimensional (2D) transition metal carbon / nitrogen compound, MXene (M... n+1 X n T xTiO2 / Ti3C2MXene (n=1,2,3, M: transition metal element, X: carbon, nitrogen or carbon element, Tx: surface functional group -OH, -F or -O) has attracted widespread attention due to its unique two-dimensional structure and excellent conductivity. Among them, two-dimensional (2D) Ti3C2MXene has broad potential in the field of photocatalysis. Due to its excellent conductivity and abundant surface groups, Ti3C2MXene is widely used as an auxiliary catalyst to improve photocatalytic activity, accelerate electron migration, and inhibit the recombination of photoexcited electrons and holes. At the same time, the Ti3C2MXene precursor has an ordered layered structure and uniform carbon source distribution, making it an ideal material for preparing TiO2-based photocatalytic composite materials. However, most TiO2 / Ti3C2 composite materials are currently in powder form. During the photocatalytic degradation of organic pollutants in aquatic systems, samples are constantly lost and difficult to recover, resulting in high costs and secondary pollution, which seriously restricts practical applications.

[0005] Based on the above realities, developing efficient photocatalysts that are stable and easy to recycle is one of the key research directions for photocatalytic degradation of organic pollutants. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a Ti3C2-MXene / TiO2 Schottky heterojunction fiber photocatalyst, its preparation method, and its application, so as to achieve the goal of efficiently degrading organic matter under visible light irradiation and facilitating catalyst recovery.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] This invention first discloses a method for preparing a Ti3C2-MXene / TiO2 Schottky heterojunction fiber photocatalyst, comprising the following steps:

[0009] S1. Preparation of Ti3C2-MXene colloidal solution:

[0010] Lithium fluoride was added to hydrochloric acid solution and stirred for a period of time. Then Ti3AlC2 powder was slowly added to it and the temperature was raised to react. The acidic solution after the reaction was washed with deionized water until the pH value was close to neutral. After centrifugation, Ti3C2-MXene colloidal solution was obtained.

[0011] S2, Preparation of Ti3C2-MXene fibers by alkalization / dealkalization process:

[0012] Add the alkaline solution to the Ti3C2-MXene colloidal solution obtained in step S1, let it stand for 30-60 minutes, then wash with deionized water until the pH value is close to neutral, and use wet spinning technology to prepare Ti3C2-MXene fibers.

[0013] S3. Preparation of Ti3C2-MXene / TiO2 Schottky heterojunction fibers:

[0014] The dried Ti3C2-MXene fibers from step S2 were placed in a ceramic boat and calcined at 300-500℃ for 2-6 hours. Finally, the product was naturally cooled to room temperature to obtain Ti3C2-MXene / TiO2 Schottky heterojunction fibers.

[0015] Preferably, in step S1, the mass ratio of lithium fluoride to Ti3AlC2 powder is 1:(0.5~2).

[0016] More preferably, in the aforementioned step S1, the temperature is raised to 35~55°C and the reaction is carried out for 12~24 hours.

[0017] More preferably, in step S2 above, the alkaline solution is a 1 mol / L NaOH solution. The alkalization treatment allows for the rapid formation of MXene flocculation in the Ti3C2-MXene colloidal solution, while simultaneously introducing a large number of -OH groups. These -OH terminal groups enable more efficient transfer of photoinduced electrons from the semiconductor to the Ti3C2 cocatalyst, and also provide more active sites, thereby improving photocatalytic activity.

[0018] More preferably, in step S3, the heating rate is 2~5℃ / min.

[0019] As a preferred embodiment, the specific operation process of the aforementioned step S1 is as follows: add 1-2g of lithium fluoride to 15-20 mL of 9 M hydrochloric acid solution and stir for 5-10 minutes; then slowly add 1-2g of Ti3AlC2 powder to the above solution and react at 35-55℃ for 21-24 h; then wash the acidic solution after the reaction with deionized water until the pH value is close to neutral; then centrifuge at 3500-5000 rpm for 1-2 h to obtain Ti3C2-MXene colloidal solution.

[0020] As a preferred option, the specific operation process of the aforementioned step S2 is as follows: add 5~10 mL of 1mol / L NaOH solution to 5~10 mL of Ti3C2-MXene colloidal solution and let it stand for 30~60 min. Then wash the solution with deionized water until the pH is close to neutral. Use wet spinning technology to prepare Ti3C2-MXene fibers from the solution.

[0021] As a preferred option, the specific operation process of the aforementioned step S3 is as follows: the dried alkalized Ti3C2-MXene fiber is placed in a 200 ml ceramic boat and heated to 300-500°C at a heating rate of 2-5°C / min. The calcination is continued at this temperature for 2-6 hours, and then the product is naturally cooled to room temperature to obtain Ti3C2-MXene / TiO2 Schottky heterojunction fiber.

[0022] The present invention also discloses a Ti3C2-MXene / TiO2 Schottky heterojunction fiber photocatalyst, which is prepared by the aforementioned method, and the cross-section of the product exhibits a broccoli-like morphology of porous MXene nanosheets stacked together.

[0023] In addition, this invention also discloses the application of the Ti3C2-MXene / TiO2 Schottky heterojunction fiber photocatalyst as described above in the degradation of rhodamine, with a degradation efficiency of up to 97% in 1 hour.

[0024] The specific steps for application are as follows: The alkalized Ti3C2-MXene / TiO2 Schottky heterojunction fiber photocatalyst is mixed with water containing organic pollutants, stirred, and subjected to a photocatalytic reaction to complete the degradation of organic pollutants in the water. The content of the Ti3C2-MXene / TiO2 Schottky heterojunction fiber photocatalyst is 60-80 mg, the concentration of the organic pollutant selective dye (Rhodamine) solution is 20-30 mg / L, and the stirring time is 0-120 min. The photocatalytic reaction is carried out under xenon lamp irradiation, with the xenon lamp having a light power of 300W-500W, the photocatalytic reaction temperature being 25℃-35℃, and the time being 0-120 min.

[0025] The advantages of this invention are:

[0026] (1) This invention prepares a novel photocatalyst through three simple and easily implemented steps. A unique alkalization / dealkalization process is used to add NaOH to a Ti3C2-MXene colloidal solution, introducing sodium ions and avoiding the flocculation failure of the Ti3C2-MXene colloidal solution, thereby obtaining a novel MXene fiber with a broccoli-like structure. Compared with previously reported MXene fibers, its structure features loosely packed MXene sheets. This novel microstructure design effectively solves the problem of limited in-situ growth of TiO2 nanoparticles during subsequent heat treatment, while providing more electron transport paths and accelerating the separation of electrons and holes. Furthermore, the -OH terminal group allows photoinduced electrons to be transferred more effectively from the semiconductor to the Ti3C2 cocatalyst, and the -OH terminal group can provide more active sites, further improving photocatalytic activity.

[0027] (2) This invention constructs a one-dimensional (1D) fiber structure of alkalized Ti3C2-MXene using wet spinning technology, and combines it with controllable calcination to allow TiO2 to grow in situ on the alkalized Ti3C2-MXene fiber. The final Ti3C2-MXene / TiO2 Schottky heterojunction fiber can absorb and utilize a wider range of visible light in the photocatalytic reaction. At the same time, the fibrous photocatalyst is easier to recycle in the water system, saving costs and avoiding secondary pollution. Studies have shown that the structural morphology formed varies with the calcination temperature and time. The process condition of calcination at 300℃ for 3h can construct the Ti3C2-MXene / TiO2 Schottky heterojunction structure most efficiently, enabling RhB to degrade rapidly under visible light irradiation, with a degradation efficiency of up to 97% within 1h. It is a novel photocatalyst with excellent comprehensive performance.

[0028] (3) The photocatalyst obtained by the preparation method of the present invention has a novel structure and excellent performance. It has a very good visible light photocatalytic effect and can degrade organic matter under visible light. It has the characteristics of high efficiency, energy saving and environmental protection. It has a very good degradation effect on rhodamine. Moreover, the introduction of TiO2 makes Ti3C2T x The fiber is hydrophobic and does not collapse in water, exhibiting excellent structural stability. This provides a basis for further development of recyclable photocatalysts, which have promising application prospects in wastewater treatment, waste gas treatment, and other fields. Attached Figure Description

[0029] Figure 1 These are XRD patterns of the products of Examples 1-4 and Comparative Examples 1-4 of the present invention;

[0030] Figure 2 These are surface SEM comparison images of the products of Example 2 (left) and Comparative Example 2 (right) of the present invention;

[0031] Figure 3 These are cross-sectional SEM comparison images of the products of Example 2 (left) and Comparative Example 2 (right) of the present invention;

[0032] Figure 4 These are the ultraviolet-visible (UV-vis) absorption spectra of the products of Examples 1 and 2 and Comparative Examples 1 and 2 of the present invention;

[0033] Figure 5 These are the degradation effects of the products of Examples 1-4 and Comparative Examples 1-4 on the dye rhodamine.

[0034] Figure 6 This is a comparison diagram of the stability of the products of Example 2 and Comparative Example 2 of the present invention under severe disturbance in water;

[0035] Figure 7This is a comparison chart of the degradation efficiency of the product after multiple cycles in Example 2 of the present invention. Detailed Implementation

[0036] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0037] Unless otherwise specified, all raw materials used in this invention are commercially available.

[0038] Example 1:

[0039] S1. Add 1 g of lithium fluoride (LiF) to 15 mL of 9 M hydrochloric acid (HCl) and stir for 5 minutes. Slowly add 1 g of Ti3AlC2 powder to the above solution and react at 50 °C for 12 h. Then wash the acidic solution after the reaction with deionized water (DI) until the pH value is close to neutral. Subsequently, centrifuge at 3500 rpm for 1 h to obtain a Ti3C2-MXene colloidal solution.

[0040] S2. Add 5 mL of 1 mol / L NaOH solution to 5 mL of Ti3C2-MXene colloidal solution and let stand for 30 min. Then wash the solution with deionized water (DI) until the pH value is close to neutral. Subsequently, the solution is used to prepare Ti3C2-MXene fibers using wet spinning technology.

[0041] S3. The dried Ti3C2-MXene fibers were placed in a 200 ml ceramic boat and heated to 300°C at a heating rate of 2°C / min. The calcination was continued at this temperature for 2 hours. The product was then naturally cooled to room temperature to obtain the Ti3C2-MXene / TiO2 Schottky heterojunction fiber catalyst.

[0042] Example 2:

[0043] S1. Add 1g of lithium fluoride (LiF) to 20mL of 9M hydrochloric acid (HCl) and stir for 5 minutes. Slowly add 2g of Ti3AlC2 powder to the above solution and react at 55℃ for 20h. Then wash the acidic solution after reaction with deionized water (DI) until the pH value is close to neutral. Subsequently, centrifuge at 4500 rpm for 1h to obtain Ti3C2-MXene colloidal solution.

[0044] S2. Add 7 mL of 1 mol / L NaOH solution to 7 mL of Ti3C2-MXene colloidal solution and let stand for 40 min. Then wash the solution with deionized water (DI) until the pH value is close to neutral. Subsequently, Ti3C2-MXene fibers are prepared by wet spinning technology.

[0045] S3. The dried Ti3C2-MXene fibers were placed in a 200 ml ceramic boat and heated to 300°C at a heating rate of 3°C / min. The calcination was continued at this temperature for 3 hours. The product was then naturally cooled to room temperature to obtain the Ti3C2-MXene / TiO2 Schottky heterojunction fiber catalyst.

[0046] Example 3:

[0047] S1. Add 1.5 g of lithium fluoride (LiF) to 17 mL of 9 M hydrochloric acid (HCl) and stir for 5 minutes. Slowly add 1 g of Ti3AlC2 powder to the above solution and react at 40 °C for 24 h. Then wash the acidic solution after the reaction with deionized water (DI) until the pH value is close to neutral. Subsequently, centrifuge at 5000 rpm for 1.5 h to obtain a Ti3C2-MXene colloidal solution.

[0048] S2. Add 9 mL of 1 mol / L NaOH solution to 9 mL of Ti3C2-MXene colloidal solution and let stand for 50 min. Then wash the solution with deionized water (DI) until the pH value is close to neutral. Subsequently, Ti3C2-MXene fibers are prepared by wet spinning technology.

[0049] S3. The dried Ti3C2-MXene fibers were placed in a 200 ml ceramic boat and heated to 500°C at a heating rate of 4°C / min. The calcination was continued at this temperature for 4 hours. The product was then naturally cooled to room temperature to obtain the Ti3C2-MXene / TiO2 Schottky heterojunction fiber catalyst.

[0050] Example 4:

[0051] S1. Add 2g of lithium fluoride (LiF) to 19mL of 9M hydrochloric acid (HCl) and stir for 5 minutes. Slowly add 1g of Ti3AlC2 powder to the above solution and react at 35℃ for 24h. Then wash the acidic solution after the reaction with deionized water (DI) until the pH value is close to neutral. Subsequently, centrifuge at 5000 rpm for 1h to obtain Ti3C2-MXene colloidal solution.

[0052] S2. Add 10 mL of 1 mol / L NaOH solution to 10 mL of Ti3C2-MXene colloidal solution and let stand for 60 min. Then wash the solution with deionized water (DI) until the pH value is close to neutral. Subsequently, Ti3C2-MXene fibers are prepared by wet spinning technology.

[0053] S3. The dried Ti3C2-MXene fibers were placed in a 200 ml ceramic boat and heated to 400°C at a heating rate of 5°C / min. The calcination was continued at this temperature for 6 hours. The product was then naturally cooled to room temperature to obtain the Ti3C2-MXene / TiO2 Schottky heterojunction fiber catalyst.

[0054] Comparative Example 1

[0055] S1. Add 1 g of lithium fluoride (LiF) to 15 mL of 9 M hydrochloric acid (HCl) and stir for 5 minutes. Slowly add 1 g of Ti3AlC2 powder to the above solution and react at 50 °C for 12 h. Then wash the acidic solution after the reaction with deionized water (DI) until the pH value is close to neutral. Subsequently, centrifuge at 3500 rpm for 1 h to obtain a Ti3C2-MXene colloidal solution.

[0056] S2. Ti3C2-MXene fibers were prepared by wet spinning of Ti3C2-MXene colloidal solution.

[0057] S3. Place the dried Ti3C2-MXene fibers in a 200 ml ceramic boat and heat to 300°C at a heating rate of 2°C / min. Continuously calcine at this temperature for 2 hours. Then, allow the product to cool naturally to room temperature to obtain Ti3C2-MXene / TiO2 Schottky heterojunction fibers.

[0058] Comparative Example 2

[0059] S1. Add 1g of lithium fluoride (LiF) to 20mL of 9M hydrochloric acid (HCl) and stir for 5 minutes. Slowly add 2g of Ti3AlC2 powder to the above solution and react at 55℃ for 20h. Then wash the acidic solution after reaction with deionized water (DI) until the pH value is close to neutral. Subsequently, centrifuge at 4500 rpm for 1h to obtain Ti3C2-MXene colloidal solution.

[0060] S2. Ti3C2-MXene fibers were prepared by wet spinning of Ti3C2-MXene colloidal solution.

[0061] S3. Place the dried Ti3C2-MXene fibers in a 200 ml ceramic boat and heat to 300°C at a heating rate of 3°C / min. Continuously calcine at this temperature for 3 hours. Then, allow the product to cool naturally to room temperature to obtain Ti3C2-MXene / TiO2 Schottky heterojunction fibers.

[0062] Comparative Example 3

[0063] S1. Add 1.5 g of lithium fluoride (LiF) to 17 mL of 9 M hydrochloric acid (HCl) and stir for 5 minutes. Slowly add 1 g of Ti3AlC2 powder to the above solution and react at 40 °C for 24 h. Then wash the acidic solution after the reaction with deionized water (DI) until the pH value is close to neutral. Subsequently, centrifuge at 5000 rpm for 1.5 h to obtain a Ti3C2-MXene colloidal solution.

[0064] S2. Ti3C2-MXene fibers were prepared by wet spinning of Ti3C2-MXene colloidal solution.

[0065] S3. The dried Ti3C2-MXene fibers were placed in a 200 ml ceramic boat and heated to 500°C at a heating rate of 4°C / min. The calcination was continued at this temperature for 4 hours. The product was then naturally cooled to room temperature to obtain Ti3C2-MXene / TiO2 Schottky heterojunction fibers.

[0066] Comparative Example 4

[0067] S1. Add 2g of lithium fluoride (LiF) to 19mL of 9M hydrochloric acid (HCl) and stir for 5 minutes. Slowly add 1g of Ti3AlC2 powder to the above solution and react at 35℃ for 24h. Then wash the acidic solution after the reaction with deionized water (DI) until the pH value is close to neutral. Subsequently, centrifuge at 5000 rpm for 1h to obtain Ti3C2-MXene colloidal solution.

[0068] S2. Ti3C2-MXene fibers were prepared by wet spinning of Ti3C2-MXene colloidal solution.

[0069] S3. The dried Ti3C2-MXene fibers were placed in a 200 ml ceramic boat and heated to 400°C at a heating rate of 5°C / min. The calcination was continued at this temperature for 6 hours. The product was then naturally cooled to room temperature to obtain Ti3C2-MXene / TiO2 Schottky heterojunction fibers.

[0070] Structural characterization and performance testing

[0071] (1) XRD characterization

[0072] Figure 1The X-ray diffraction (XRD) patterns shown are, from top to bottom, the XRD patterns of Comparative Examples 1-4 and Examples 1-4. As can be seen from the figures, the diffraction peaks of TiO2 appear at 25.2° and 48.2°, belonging to the (101) and (200) crystal planes of anatase TiO2, respectively, and the intensity of the TiO2 diffraction peaks increases with increasing calcination time. In addition, the typical MXene diffraction peaks in Comparative Examples 1-4 and Examples 1-4 are located at 8.0° and 5.9°, respectively. This is attributed to the alkali treatment process further increasing the interlayer spacing of Ti3C2MXene, and the porosity inside the fibers is conducive to the in-situ growth of TiO2 nanoparticles. Furthermore, the peak intensity increases with increasing calcination time, indicating that the calcination time is related to the proportion of TiO2 nanoparticles. All samples confirm the coexistence of TiO2 and Ti3C2 phases, indicating successful in-situ growth of TiO2.

[0073] (2) SEM morphological characterization

[0074] Figure 2 The images shown are scanning electron microscope (SEM) images of the photocatalysts of Example 2 (left) and Comparative Example 2 (right) of the present invention. Figure 2 As can be seen, the fiber diameter obtained in Example 2 is larger than that in Comparative Example 2, and the fiber surface has more wrinkles and is rougher.

[0075] Figure 3 The images shown are cross-sectional scanning electron microscope (SEM) images of the photocatalysts of Example 2 (left) and Comparative Example 2 (right) of the present invention. Figure 3 As shown in the right figure, in the fiber prepared in Comparative Example 2, the Ti3C2 flakes are aligned along the fiber axis, and the fiber cross-section exhibits a layered structure with very compact stacking between the flakes. Furthermore, the combination... Figure 3 As can be seen in the left figure, the fiber prepared in Example 2 exhibits a large interlamellar spacing and a porous structure. The cross-sectional surface has a cauliflower-like shape, and the lamellar structure of the fiber is filled with TiO2 nanoparticles.

[0076] Under the same process conditions, Comparative Example 2's Ti3C2T x The fibers show almost no visible TiO2 nanoparticles, indicating that the Ti3C2T fiber is treated with an alkalization / dealkalization process. x The microstructure of the fiber is more conducive to the in-situ growth of TiO2 nanoparticles, thereby optimizing the overall performance of the photocatalyst.

[0077] (3) Ultraviolet-visible (UV-vis) absorption spectrum

[0078] Figure 4 The images shown are the ultraviolet-visible (UV-vis) absorption spectra of Comparative Examples 1-2 and Examples 1-2 of the present invention.

[0079] Due to the unique light absorption of carbonaceous materials, Comparative Examples 1-2 and Examples 1-2 exhibit full-spectrum absorption from ultraviolet to visible light. After pretreatment with an alkalization / de-alkalization process, the overall light absorption intensity of Examples 1-2 decreased compared to Comparative Examples 1-2. After calcination, the light absorption intensity of Comparative Example 2 and Example 2 decreased with increasing calcination time, possibly due to the appearance of TiO2 after calcination, and the increase in TiO2 content with increasing calcination time. This further demonstrates the successful in-situ growth of TiO2.

[0080] (4) Experimental verification of photocatalytic degradation of dye (Rhodamine B) in water by photocatalyst

[0081] Experimental Methods: The photocatalytic degradation performance of rhodamine was evaluated under visible light (λ > 420 nm) illumination using a 300 W xenon lamp (CEL-HXF300, Beijing China Education Golden Light Co., Ltd.) with a light cutoff filter. The light intensity was controlled at 300 mW / cm² using a light power meter. -2 .

[0082] The general method is as follows:

[0083] 1) Add 80 mg of photocatalyst to 100 ml of rhodamine solution (20 mg / ml) and leave in the dark for 30 min to reach adsorption-desorption equilibrium.

[0084] 2) During the illumination process, collect 3 ml of sample every 20 minutes and measure the absorbance of the sample using a UV-Vis spectrophotometer.

[0085] 3) Calculate the degradation rate (%) of Rhodamine B based on the intensity change of the 550nm absorption peak in the measured solution absorption spectrum: 1 - C t / C0=1-A t / A0. Where C0 and A0 are the initial concentrations of Rhodamine B in water before illumination and their absorbance at 550 nm, respectively; C... t and A t It is the concentration of Rhodamine B in water and its absorbance at 550 nm after a certain period of illumination.

[0086] Figure 5 The graphs shown depict the concentration changes of the photocatalysts prepared in Examples 1-4 and Comparative Examples 1-4 of this invention under 300W xenon lamp irradiation, degrading the dye Rhodamine B. Figure 5 It is clear that, under basically the same process conditions such as calcination, the fiber degradation effect of each embodiment of the present invention is significantly improved compared with the fiber of the comparative example. The applicant believes that this is mainly due to the fact that the alkalization / dealkalization process pretreatment of the -OH end groups on the MXene surface can provide more active sites.

[0087] from Figure 5 As can be seen, Example 2 is the preferred embodiment, demonstrating the best photocatalytic RhB degradation efficiency, achieving 97% degradation of RhB within 60 minutes. Furthermore, it was observed that the photocatalytic activity of the sample decreased with increasing calcination time. This is mainly due to the decreasing light utilization efficiency caused by the gradual increase in TiO2 content with increasing calcination time. This further illustrates that multiple factors, including alkalization / dealkalization pretreatment, calcination time, and calcination temperature, significantly influence the obtaining of TiO2@Ti3C2T with optimal photocatalytic activity. x Fibers have a synergistic effect.

[0088] (5) Recyclability and recyclability

[0089] Figure 6 The structural stability of the fibers in Example 2 was demonstrated under a series of severe disturbances in water. Figure 6 The labels a and d respectively show the state of the fibers in water in Example 2, and eh respectively show the state of the fibers in water in Comparative Example 2. Among them, (a) and (e) are when the fibers are first placed in water, (b) and (f) are stirred for 10 minutes, (c) and (g) are left to stand for 72 hours, and (d) and (h) are sonicated for 10 minutes.

[0090] In contrast, it is evident that the fibers in Comparative Example 2 collapsed rapidly in water due to mechanical agitation, such as... Figure 6 As shown in Figure eh; while the structure of Example 2 was well preserved, indicating that the alkalization and calcination process successfully introduced TiO2 into the fiber, improving the Ti3C2T... x The structural stability of the fiber in water ensures the stability of TiO2@Ti3C2T x The recyclability of fibers in wastewater treatment.

[0091] In addition, from Figure 7 As can be seen, the fiber from Example 2 exhibits highly reliable stability in degradation efficiency after four cycles of recovery from water. The efficiency remains essentially unchanged in the first three cycles, while the slight decrease in the fourth cycle is likely due to sample mass loss. Therefore, this invention will undoubtedly provide a novel solution for recyclable photocatalysts.

[0092] In summary, this invention proposes a novel Ti3C2-MXene / TiO2 Schottky heterojunction fiber photocatalyst prepared through a simple wet spinning technique and calcination treatment. This catalyst can efficiently degrade organic matter under visible light irradiation. First, the wet spinning technique constructs Ti3C2-MXene into a one-dimensional (1D) fiber structure, which promotes the development of an easily recyclable and highly efficient photocatalyst. Next, the surface alkalization / dealkalization treatment of Ti3C2-MXene not only alters its dense lamellar structure, making it more coiled and fluffy, but also allows the -OH terminal groups on the Ti3C2 surface to more effectively transfer photoinduced electrons from the semiconductor to the Ti3C2 cocatalyst. Furthermore, the -OH terminal groups provide more active sites, thereby improving photocatalytic activity and endowing the product with more outstanding photocatalytic performance. This catalyst is a novel visible light photocatalyst with excellent catalytic performance, exhibiting good photodegradation ability for organic pollutants under visible light. Simultaneously, the catalyst has a very stable fibrous structure, making it convenient for recovery and reusable in water applications. Furthermore, the catalyst has a simple preparation process, uses environmentally friendly reagents, and has the advantages of high efficiency, energy saving, environmental protection, low cost, and high safety. It is suitable for large-scale production and has good application prospects in fields such as wastewater treatment and waste gas treatment.

[0093] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the above embodiments do not limit the present invention in any way, and all technical solutions obtained by equivalent substitution or equivalent transformation fall within the protection scope of the present invention.

Claims

1. A method for preparing a Ti3C2-MXene / TiO2 Schottky heterojunction fiber photocatalyst, characterized in that, The method comprises the following steps: S1, preparing a Ti3C2-MXene colloidal solution: Lithium fluoride is added to a hydrochloric acid solution, stirred for a period of time, and then Ti3AlC2 powder is slowly added thereto, and the reaction is carried out at an elevated temperature; then the acidic solution after the reaction is washed with deionized water until the pH value of the washing liquid is neutral, and a Ti3C2-MXene colloidal solution is obtained after centrifugal separation; S2, preparing Ti3C2-MXene fibers through an alkalization / dealkalization process: An alkaline solution is added to the Ti3C2-MXene colloidal solution prepared in step S1, and the solution is left to stand for 30-60 min, then washed with deionized water until the pH value of the washing liquid is neutral, and a Ti3C2-MXene fiber is prepared from the solution by using a wet spinning process; The alkaline solution is a NaOH solution with a concentration of 1 mol / L; S3, preparing a Ti3C2-MXene / TiO2 Schottky heterojunction fiber: The Ti3C2-MXene fiber dried in step S2 is placed in a porcelain boat, and calcination is carried out at a temperature of 300-500℃ for 2-6 h; finally, the product is naturally cooled to room temperature to obtain a Ti3C2-MXene / TiO2 Schottky heterojunction fiber.

2. The preparation method of the Ti3C2-MXene / TiO2 Schottky heterojunction fiber photocatalyst according to claim 1, characterized in that, In step S1, the mass ratio of lithium fluoride to Ti3AlC2 powder is 1: (0.5-2), the temperature is raised to 35-55℃, and the reaction is carried out for 12-24 h.

3. The preparation method of the Ti3C2-MXene / TiO2 Schottky heterojunction fiber photocatalyst according to claim 1, characterized in that, In step S2, the specific operation process of the wet spinning process is as follows: the Ti3C2-MXene colloidal solution is used as raw material, added to a plastic syringe, matched with a metal needle, injected into a rotating culture dish containing isopropyl alcohol at a certain rate, and the fiber is collected therefrom.

4. The preparation method of the Ti3C2-MXene / TiO2 Schottky heterojunction fiber photocatalyst according to claim 1, characterized in that, In step S3, the heating rate is 2-5℃ / min.

5. The method for preparing a Ti3C2-MXene / TiO2 Schottky heterojunction fiber photocatalyst according to claim 1, characterized in that, The specific operation process of step S1 is as follows: 1-2 g of lithium fluoride is added to 15-20 mL of 9 M hydrochloric acid solution, stirred for 5-10 min; then 1-2 g of Ti3AlC2 powder is slowly added to the above solution, and the reaction is carried out at 35-55℃ for 21-24 h; then the acidic solution after the reaction is washed with deionized water until the pH value is neutral, and then centrifuged at 3500-5000 rpm for 1-2 h to obtain a Ti3C2-MXene colloidal solution.

6. The method for preparing a Ti3C2-MXene / TiO2 Schottky heterojunction fiber photocatalyst according to claim 1, characterized in that, The specific operation process of step S2 is as follows: 5-10 mL of 1 mol / L NaOH solution is added to 5-10 mL of Ti3C2-MXene colloidal solution, left to stand for 30-60 min, then the solution is washed with deionized water until the pH value is neutral, and a Ti3C2-MXene fiber is prepared from the solution by using a wet spinning technique.

7. The method for preparing a Ti3C2-MXene / TiO2 Schottky heterojunction fiber photocatalyst according to claim 1, characterized in that, The specific operation process of step S3 is as follows: the dried Ti3C2-MXene fiber is placed in a 200 ml porcelain boat, heated to 300-500℃ at a heating rate of 2-5℃ / min, calcined at this temperature for 2-6 h, and then the product is naturally cooled to room temperature to obtain a Ti3C2-MXene / TiO2 Schottky heterojunction fiber.

8. A Ti3C2-MXene / TiO2 Schottky heterojunction fiber photocatalyst, characterized in that, Prepared by the method of any one of claims 1-7.

9. Use of the Ti3C2-MXene / TiO2 Schottky heterojunction fiber photocatalyst according to claim 8 for the degradation of Rhodamine.

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