Method for degrading organic pollutants by using V4C3 MXene material

Abstract

The invention provides a method for degrading organic pollutants by using a V4C3MXene material, which comprises the following steps of: adding the V4C3MXene material which is etched within 24 hours into a water body containing the organic pollutants, and catalyzing the organic pollutants in the water body to degrade by using the V4C3MXene material under the conditions of darkness, stirring and cold and hot temperature difference circulation. The V4C3MXene material which is etched within 24 hours can effectively degrade organic pollutants under the dark condition and the cold and hot temperature difference circulation condition.

Description

Technical Field

[0001] The present invention belongs to the technical field of organic pollutant treatment, and relates to a method for degrading organic pollutants under dark conditions by utilizing piezoelectric-pyroelectric V4C3 Mxene materials. Background Art

[0002] The accelerated development of industrial and pharmaceutical technologies has led to a significant increase in environmental pollution, posing a challenge to the sustainable development of human civilization. Dyes and antibiotics, classified as highly hazardous water pollutants, not only pose risks to human health but also significantly damage the balance and function of aquatic ecosystems. Photocatalysis has enormous potential for addressing energy crises and mitigating environmental pollution. However, the diffuse and regional nature of sunlight limits its application. Conventional photocatalytic technology is unable to purify industrial wastewater containing antibiotics and synthetic dyes under dark conditions. Summary of the Invention

[0003] In response to the problems existing in the prior art, the present invention provides a method for degrading organic pollutants using V4C3 MXene materials. The V4C3 MXene materials within 24 hours after etching can effectively degrade organic pollutants under dark conditions and hot and cold temperature cycle conditions.

[0004] The present invention is achieved through the following technical solutions:

[0005] A method for degrading organic pollutants using V4C3 MXene material comprises adding V4C3 MXene material within 24 hours after etching to a water body containing organic pollutants, and utilizing the V4C3 MXene material to catalyze the degradation of organic pollutants in the water body under conditions of darkness, stirring, and hot and cold temperature cycles.

[0006] Preferably, in the method of degrading organic pollutants using V4C3 MXene material, the temperature range of the hot and cold temperature difference cycle is 6°C to 35°C.

[0007] Preferably, in the method of degrading organic pollutants using V4C3 MXene material, the number of hot and cold temperature difference cycles is 1 to 5 times.

[0008] Preferably, in the method of degrading organic pollutants using V4C3 MXene material, the stirring time is 0.5 to 1 hour.

[0009] Preferably, in the method of degrading organic pollutants using V4C3 MXene material, the stirring speed is 800 r / min to 1200 r / min.

[0010] Preferably, in the method of degrading organic pollutants using V4C3 MXene material, the concentration of the V4C3 MXene material in water is 0.08 to 0.10 g / mL.

[0011] Preferably, in the method for degrading organic pollutants using V4C3 MXene material, the preparation method of the V4C3 MXene material includes:

[0012] Step 1: Disperse V4AlC3 powder in HF solution to form a mixed solution, seal the mixed solution, and then stir at 55-65°C for etching reaction to obtain a multilayer vanadium carbide dispersion;

[0013] Step 2: The multilayer vanadium carbide dispersion is centrifuged, and the resulting precipitate is washed and dried to obtain V4C3 MXene material.

[0014] Furthermore, in the preparation method of the V4C3 MXene material, the stirring time in step 1 is 48 to 120 hours.

[0015] Furthermore, in the preparation method of the V4C3 MXene material, the washing in step 2 is specifically: first centrifugally washing with deionized water until the pH value of the obtained supernatant is 6.5-7, and then washing with anhydrous ethanol multiple times.

[0016] Preferably, in the method of degrading organic pollutants using V4C3 MXene materials, the organic pollutants are antibiotics or dyes.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The V4C3 MXene material of the present invention has piezoelectric properties within 24 hours after etching, and the V4C3 MXene material within 24 hours after etching stores electrons and holes under the binding action of the piezoelectric polarization electric field. Under dark conditions, the V4C3 MXene material generates a deformation polarization electric field under the action of low-frequency stirring mechanical shear stress, which drives the release of electrons and holes stored in itself and generates piezoelectric charges, giving the V4C3 MXene material energy storage piezoelectric catalysis and piezoelectric catalytic degradation properties under dark conditions; under dark conditions, hot and cold temperature difference cycles cause the V4C3 MXene material to generate a polarization electric field caused by temperature fluctuations, and the polarization electric field caused by temperature fluctuations drives the release of electrons and holes stored in itself and generates positive and negative charges, giving the V4C3 MXene material pyroelectric energy storage catalysis and pyroelectric catalytic degradation properties under dark conditions. The optimized synergistic effect of piezoelectric effect and pyroelectric effect greatly improves the catalytic activity of the material and the degradation efficiency of organic pollutants. Therefore, within 24 hours after etching, the V4C3 MXene material has piezoelectric-pyroelectric properties, and has good broad-spectrum degradation and cyclic degradation effects on organic pollutants such as antibiotics and dyes under dark conditions and hot and cold temperature cycle conditions.

[0019] The preparation conditions of the V4C3 MXene material of the present invention are simple and mild, and large-scale preparation can be achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 XRD patterns of V4C3 MXene materials prepared in Examples 1 to 4 of the present invention;

[0022] Figure 2 This is the SEM image of the V4C3 MXene material prepared in Example 3 of the present invention;

[0023] Figure 3 TEM image of the V4C3 MXene material prepared in Example 3 of the present invention;

[0024] Figure 4 HRTEM image of the V4C3 MXene material prepared in Example 3 of the present invention;

[0025] Figure 5 is the absorbance curve of the V4C3 MXene material prepared in Example 3 of the present invention to 40 mg / L methylene blue under dark conditions;

[0026] Figure 6 This is the absorbance curve of the V4C3 MXene material prepared in Comparative Example 1 of the present invention to 20 mg / L methylene blue under dark conditions;

[0027] Figure 7 The V4C3 MXene material prepared in Example 3 of the present invention is heated under dark conditions for h + Electron paramagnetic resonance spectrum of

[0028] Figure 8 This is the PFM morphology of the V4C3 MXene material prepared in Example 3 of the present invention;

[0029] Figure 9 This is the PFM phase change diagram of the V4C3 MXene material prepared in Example 3 of the present invention;

[0030] Figure 10 This is the amplitude change diagram of the V4C3 MXene material prepared in Example 3 of the present invention.

[0031] Figure 11 : is the piezoelectric current diagram of the V4C3 MXene material prepared in Example 3 of the present invention under dark conditions;

[0032] Figure 12 This is the absorbance curve of the V4C3 MXene material prepared in Example 1 of the present invention to 40 mg / L methylene blue after stirring for 0.5 h in dark conditions;

[0033] Figure 13 This is the absorbance curve of the V4C3 MXene material prepared in Example 3 of the present invention to 40 mg / L methylene blue after stirring for 1 hour in dark conditions;

[0034] Figure 14 This is the absorbance curve of the V4C3 MXene material prepared in Example 3 of the present invention to 40 mg / L methylene blue after one cycle of alternating hot and cold cycles under dark conditions;

[0035] Figure 15 This is the absorbance curve of the V4C3 MXene material prepared in Example 3 of the present invention to 40 mg / L methylene blue after 5 cycles of alternating hot and cold cycles under dark conditions;

[0036] Figure 16 The energy storage piezoelectric catalytic and piezoelectric catalytic degradation performance of the V4C3 MXene catalysts prepared in Examples 1 to 4 of the present invention for 20 mg / L tetracycline under dark conditions;

[0037] Figure 17The pyroelectric energy storage catalysis and pyroelectric catalytic degradation performance of the V4C3 MXene materials prepared in Examples 1 to 4 of the present invention on 20 mg / L tetracycline after several hot and cold cycles under dark conditions;

[0038] Figure 18 The mass spectra and mass-to-charge ratios of different peak positions of the pyroelectric energy storage catalysis and pyroelectric catalysis of the V4C3 MXene material prepared in Example 3 of the present invention after one cycle of hot and cold alternation of 20 mg / L tetracycline under dark conditions;

[0039] Figure 19 The mass spectra and mass-to-charge ratios at different peak positions of the pyroelectric energy storage catalysis and pyroelectric catalysis of the V4C3 MXene material prepared in Example 3 of the present invention after five cycles of hot and cold alternation of 20 mg / L tetracycline under dark conditions are shown. DETAILED DESCRIPTION

[0040] The following describes the embodiments of the present invention through specific examples. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. The present invention may also be implemented or applied through various other specific embodiments, and the details in this specification may be modified or altered based on different viewpoints and applications without departing from the spirit of the present invention.

[0041] It should be noted that the process equipment or devices not specifically specified in the following embodiments are all conventional equipment or devices in the art.

[0042] It should be noted that the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus comprising a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to these processes, methods, products, or apparatuses. Furthermore, unless otherwise specified, the numbering of each method step is merely a convenient tool for identifying each method step, and is not intended to limit the order of arrangement of each method step or to define the scope of the present invention. Changes or adjustments to their relative relationships, without substantially changing the technical content, should also be considered within the scope of the present invention.

[0043] The method for preparing the piezoelectric-pyroelectric V4C3 MXene material of the present invention comprises the following steps:

[0044] Step 1: Disperse V4AlC3 powder in HF solution to form a mixed solution, seal the mixed solution, and then stir at 55-65°C for etching reaction to obtain a multilayer vanadium carbide dispersion;

[0045] Step 2: The multilayer vanadium carbide dispersion is centrifuged, and the resulting precipitate is washed and dried to obtain a piezoelectric-pyroelectric V4C3MXene material.

[0046] The V4C3 MXene material obtained by the above method of the present invention stores electrons and holes. In a specific embodiment, the V4C3 MXene material stores 107.83 μmol·g within 24 hours after etching. -1 electrons and 21.76 μmol·g -1 The V4C3 Mxene material has piezoelectric - pyroelectric properties, its d 33 The value is 1.26nm·V -1 Under dark conditions, V4C3 MXene is disturbed by mechanical stress and temperature changes, generating a deformation polarization electric field. This field rapidly releases stored electrons and holes in the dark, leading to energy storage piezoelectric catalysis and piezoelectric catalysis, as well as pyroelectric energy storage catalysis and pyroelectric catalysis, demonstrating excellent broad-spectrum and cyclic degradation of organic pollutants (antibiotics and dyes). However, after 24 hours of HF etching, the surface oxidation of the V4C3 MXene material reduces the concentration of stored electrons and holes. Low-frequency stirring mechanical shear stress generates a deformation polarization electric field in the V4C3 MXene material, which can only drive the generation of piezoelectric charges. Consequently, the V4C3 MXene material exhibits only piezoelectric catalytic degradation performance under dark conditions. Under dark conditions, temperature cycling generates a polarization electric field caused by temperature fluctuations, which drives the generation of positive and negative charges. Consequently, the V4C3 MXene material exhibits only pyroelectric catalytic degradation performance under dark conditions.

[0047] Therefore, the degradation of organic pollutants using V4C3 MXene materials needs to be carried out within 24 hours after etching. Specifically, the V4C3 MXene material within 24 hours after etching is added to the water body containing organic pollutants. Under the conditions of darkness, stirring and hot and cold temperature difference cycles, the V4C3 MXene material is used to catalyze the degradation of organic pollutants in the water body.

[0048] In some preferred embodiments of the present invention, the temperature range of the hot and cold temperature cycle is 6°C to 35°C. One cycle consists of heating from a low temperature to a high temperature and then cooling from a high temperature to a low temperature. The low and high temperatures can be selected within the range of 6°C to 35°C, preferably 6°C to 15°C and 25°C to 35°C. For example, the low temperature is 6°C and the high temperature is 35°C, or the low temperature is 7°C and the high temperature is 30°C. The cycle test can be performed 1 to 5 times, for example, 1 time, 3 times, 5 times, etc. The greater the number of cycles, the greater the electron concentration stored in the V4C3 MXene material.

[0049] In some preferred embodiments of the present invention, the stirring time for degrading organic pollutants is 0.5 to 1 hour, for example, 0.5 or 1 hour, and the stirring speed is 800 to 1200 rpm. V4C3 MXene exhibits a pronounced piezoelectric response under stress, and low-frequency stirring mechanical stress can store charge within the V4C3 MXene material.

[0050] In the preparation method of the piezoelectric-pyroelectric V4C3 MXene material of the present invention, in step 1, the concentration of V4AlC3 in the mixed solution is 0.08-0.10 g / mL, and the mass concentration of the HF solution used is 40%-49%.

[0051] In the method for preparing the piezoelectric-pyroelectric V4C3 MXene material of the present invention, in step 1, the mixed solution is sealed with plastic wrap and then stirred at 55-65°C for 48-120 hours to perform an etching reaction. As the etching time increases, some large V4C3 MXene chunks collapse into smaller multilayers of V4C3 MXene. The stirring time is more preferably 72-96 hours, and most preferably 96 hours.

[0052] In the preparation method of the piezoelectric-pyroelectric V4C3 MXene material of the present invention, in step 2, washing is specifically: washing with deionized water, repeating 13 to 15 times until the pH value of the supernatant is 6.5 to 7, and then washing with anhydrous ethanol; drying is drying at 65 to 75°C.

[0053] Comparative Example 1:

[0054] The preparation method of V4C3 MXene material comprises the following steps:

[0055] Step 1: 2 g of 200-mesh V4AlC3 powder was added to 20 mL of 40 wt% HF solution to form a mixture, wherein the concentration of V4AlC3 in the mixture was 0.1 g / mL. The mixture was stirred at 55°C for 96 hours to obtain a multilayer vanadium carbide dispersion.

[0056] Step 2: Centrifuge the dispersion obtained in step 1, discard the supernatant, and then wash with deionized water. Repeat this process 12 times until the pH of the supernatant reaches 7. Then wash with anhydrous ethanol three times. After centrifugation, dry the precipitate at 70°C for 12 hours to obtain V4C3MXene piezoelectric catalytic material. Place the V4C3MXene powder in a sample bag and leave it for one week.

[0057] Example 1:

[0058] The preparation method of the piezoelectric-pyroelectric V4C3 MXene material of the present invention comprises the following steps:

[0059] Step 1: 2 g of 200-mesh V4AlC3 powder was added to 20 mL of 40 wt% HF solution to form a mixture, wherein the concentration of V4AlC3 in the mixture was 0.1 g / mL. The mixture was stirred at 55°C for 48 hours to obtain a multilayer vanadium carbide dispersion.

[0060] Step 2: Centrifuge the dispersion obtained in step 1, discard the supernatant, and then wash with deionized water. Repeat this process 12 times until the pH of the supernatant reaches 7. Then wash with anhydrous ethanol 3 times. After centrifugation, dry the precipitate at 70°C for 12 hours to obtain V4C3MXene material.

[0061] Example 2:

[0062] The preparation method of the piezoelectric-pyroelectric V4C3 MXene material of the present invention comprises the following steps:

[0063] Step 1: 2 g of 200-mesh V4AlC3 powder was added to 20 mL of 40 wt% HF solution to form a mixture, wherein the concentration of V4AlC3 in the mixture was 0.1 g / mL. The mixture was stirred at 55°C for 72 h to obtain a multilayer vanadium carbide dispersion.

[0064] Step 2: Centrifuge the dispersion obtained in step 1, discard the supernatant, and then wash with deionized water. Repeat this process 12 times until the pH of the supernatant reaches 7. Then wash with anhydrous ethanol 3 times. After centrifugation, dry the precipitate at 70°C for 12 hours to obtain V4C3MXene material.

[0065] Example 3:

[0066] The preparation method of the piezoelectric-pyroelectric V4C3 MXene material of the present invention comprises the following steps:

[0067] Step 1: 2 g of 200-mesh V4AlC3 powder was added to 20 mL of 40 wt% HF solution to form a mixture, wherein the concentration of V4AlC3 in the mixture was 0.1 g / mL. The mixture was stirred at 55°C for 96 hours to obtain a multilayer vanadium carbide dispersion.

[0068] Step 2: Centrifuge the dispersion obtained in step 1, discard the supernatant, and then wash with deionized water. Repeat this process 12 times until the pH of the supernatant reaches 7. Then wash with anhydrous ethanol 3 times. After centrifugation, dry the precipitate at 70°C for 12 hours to obtain V4C3MXene material.

[0069] Example 4:

[0070] The preparation method of the piezoelectric-pyroelectric V4C3 MXene material of the present invention comprises the following steps:

[0071] Step 1: 2 g of 200-mesh V4AlC3 powder was added to 20 mL of 40 wt% HF solution to form a mixture, wherein the concentration of V4AlC3 in the mixture was 0.1 g / mL. The mixture was stirred at 55°C for 120 h to obtain a multilayer vanadium carbide dispersion.

[0072] Step 2: Centrifuge the dispersion obtained in step 1, discard the supernatant, and then wash with deionized water. Repeat this process 12 times until the pH of the supernatant reaches 7. Then wash with anhydrous ethanol 3 times. After centrifugation, dry the precipitate at 70°C for 12 hours to obtain V4C3MXene material.

[0073] Example 5:

[0074] The preparation method of the piezoelectric-pyroelectric V4C3 MXene material of the present invention comprises the following steps:

[0075] Step 1: 1.6 g of 200-mesh V4AlC3 powder was added to 20 mL of 40 wt% HF solution to form a mixture, wherein the concentration of V4AlC3 in the mixture was 0.08 g / mL. The mixture was stirred at 55°C for 96 hours to obtain a multilayer vanadium carbide dispersion.

[0076] Step 2: Centrifuge the dispersion obtained in step 1, discard the supernatant, and then wash with deionized water. Repeat this process 12 times until the pH of the supernatant reaches 7. Then wash with anhydrous ethanol 3 times. After centrifugation, dry the precipitate at 70°C for 12 hours to obtain V4C3MXene material.

[0077] Example 6:

[0078] The preparation method of the piezoelectric-pyroelectric V4C3 MXene material of the present invention comprises the following steps:

[0079] Step 1: 1.8 g of 200-mesh V4AlC3 powder was added to 20 mL of 40 wt% HF solution to form a mixture, wherein the concentration of V4AlC3 in the mixture was 0.09 g / mL. The mixture was stirred at 55°C for 96 hours to obtain a multilayer vanadium carbide dispersion.

[0080] Step 2: Centrifuge the dispersion obtained in step 1, discard the supernatant, and then wash with deionized water. Repeat this process 12 times until the pH of the supernatant reaches 7. Then wash with anhydrous ethanol 3 times. After centrifugation, dry the precipitate at 70°C for 12 hours to obtain V4C3MXene material.

[0081] Example 7:

[0082] The preparation method of the piezoelectric-pyroelectric V4C3 MXene material of the present invention comprises the following steps:

[0083] Step 1: 2 g of 200-mesh V4AlC3 powder was added to 20 mL of 49 wt% HF solution to form a mixture, wherein the concentration of V4AlC3 in the mixture was 0.10 g / mL. The mixture was stirred at 55°C for 96 hours to obtain a multilayer vanadium carbide dispersion.

[0084] Step 2: Centrifuge the dispersion obtained in step 1, discard the supernatant, and then wash with deionized water. Repeat this process 12 times until the pH of the supernatant reaches 7. Then wash with anhydrous ethanol 3 times. After centrifugation, dry the precipitate at 70°C for 12 hours to obtain V4C3MXene material.

[0085] Example 9:

[0086] 50 mg of V4C3 MXene prepared within 24 hours of Example 1 was dispersed in 50 mL of 20 mg / L tetracycline hydrochloride. Degradation experiments were conducted in the dark on an XPA-7 photochemical reactor (Nanjing Xujiang Machinery Factory). Approximately 5 mL of the solution was removed every 10 minutes and filtered through a 0.22 μm membrane. The filtrate was then tested for absorbance, and the absorbance at the maximum absorption wavelength was used to characterize the sample's degradation efficiency against the target degradation product. Under dark conditions, the degradation rate of TC was 37.09% after 10 minutes, 46.20% after 20 minutes, 51.79% after 30 minutes, 55.11% after 40 minutes, 59.32% after 50 minutes, and 60.77% after 60 minutes.

[0087] Example 10:

[0088] 50 mg of V4C3 MXene prepared within 24 hours of Example 2 was dispersed in 50 mL of 20 mg / L tetracycline hydrochloride. Degradation experiments were conducted in the dark on an XPA-7 photochemical reactor (Nanjing Xujiang Machinery Factory). Approximately 5 mL of the solution was removed every 10 minutes and filtered through a 0.22 μm membrane. The filtrate was then tested for absorbance, and the absorbance at the maximum absorption wavelength was used to characterize the sample's degradation efficiency against the target degradation product. In the dark, the degradation rate of TC was 39.86% after 10 minutes, 48.33% after 20 minutes, 54.06% after 30 minutes, 58.27% after 40 minutes, 63.59% after 50 minutes, and 66.12% after 60 minutes.

[0089] Example 11:

[0090] 50 mg of V4C3 MXene prepared within 24 hours of Example 3 was dispersed in 50 mL of 20 mg / L tetracycline hydrochloride. Degradation experiments were conducted in the dark on an XPA-7 photochemical reactor (Nanjing Xujiang Machinery Factory). Approximately 5 mL of the solution was removed every 10 minutes and filtered through a 0.22 μm membrane. The filtrate was then tested for absorbance, and the absorbance at the maximum absorption wavelength was used to characterize the sample's degradation efficiency against the target degradant. Under dark conditions, the degradation rate of TC was 54.59% after 10 minutes, 58.78% after 20 minutes, 64.35% after 30 minutes, 65.12% after 40 minutes, 66.49% after 50 minutes, and 70.63% after 60 minutes.

[0091] Example 12:

[0092] 50 mg of V4C3 MXene prepared within 24 hours of Example 4 was dispersed in 50 mL of 20 mg / L tetracycline hydrochloride. Degradation experiments were conducted in the dark on an XPA-7 photochemical reactor (Nanjing Xujiang Machinery Factory). Approximately 5 mL of the solution was removed every 10 minutes and filtered through a 0.22 μm membrane. The filtrate was then tested for absorbance, and the absorbance at the maximum absorption wavelength was used to characterize the sample's degradation efficiency against the target degradation product. Under dark conditions, the degradation rate of TC was 39.86% after 10 minutes, 47.64% after 20 minutes, 52.05% after 30 minutes, 57.42% after 40 minutes, 60.88% after 50 minutes, and 64.19% after 60 minutes.

[0093] Example 13:

[0094] 50 mg of the V4C3 MXene prepared in Example 1 was weighed and dispersed in a 50 mL beaker containing 20 mg / L tetracycline hydrochloride. A pyroelectrocatalytic experiment on the V4C3 MXene was conducted in the dark under hot and cold cycles between 6 and 35°C. The beaker was first kept at 6°C for 10 minutes, then heated to 35°C over 5 minutes and held for 10 minutes, then cooled back to 6°C over 5 minutes and held for 10 minutes. This cycle was repeated twice, forming a single hot and cold cycle. After each cycle, 3 mL of the suspension was removed from the glass bottle and centrifuged. The absorbance of the dye solution was measured using a UV-visible spectrophotometer. Under dark conditions, the degradation rate of the V4C3 MXene material prepared in Example 1 for 20 mg / L TC was 39.02% after the first thermal release cycle; the degradation rate was 44.22% after the second cycle; the degradation rate was 54.81% after the third thermal release cycle; the degradation rate was 61.84% after the fourth thermal release cycle; and the degradation rate of V4C3 MXene for tetracycline was 63.71% after five cycles.

[0095] Example 14:

[0096] 50 mg of the V4C3 MXene prepared in Example 2 was weighed and dispersed in a 50 mL beaker containing 20 mg / L tetracycline hydrochloride. A pyroelectrocatalytic experiment on the V4C3 MXene was conducted in the dark under hot and cold cycles between 6 and 35°C. The beaker was first kept at 6°C for 10 minutes, then heated to 35°C over 5 minutes and held for 10 minutes, and then cooled back to 6°C over 5 minutes and held for 10 minutes. This cycle was repeated twice, forming a single hot and cold cycle. After each cycle, 3 mL of the suspension was removed from the glass bottle and centrifuged. The absorbance of the dye solution was measured using a UV-visible spectrophotometer. Under dark conditions, the degradation rate of the V4C3 MXene material prepared in Example 1 for 20 mg / L TC was 37.83% after the first thermal release cycle; the degradation rate was 44.98% after the second cycle; the degradation rate was 46.2% after the third thermal release cycle; the degradation rate was 48.75% after the fourth thermal release cycle, and the degradation rate of V4C3 MXene for tetracycline was 50.27% after five cycles.

[0097] Example 15:

[0098] 50 mg of the V4C3 MXene prepared in Example 3 was weighed and dispersed in a 50 mL beaker containing 20 mg / L tetracycline hydrochloride. A pyroelectrocatalytic experiment on the V4C3 MXene was conducted in the dark under hot and cold cycles between 6 and 35°C. The beaker was first kept at 6°C for 10 minutes, then heated to 35°C over 5 minutes and held for 10 minutes, then cooled back to 6°C over 5 minutes and held for 10 minutes. This cycle was repeated twice, forming a single hot and cold cycle. After each cycle, 3 mL of the suspension was removed from the glass bottle and centrifuged. The absorbance of the dye solution was measured using a UV-visible spectrophotometer. Under dark conditions, the degradation rate of the V4C3 MXene material prepared in Example 1 for 20 mg / L TC was 52.06% after the first thermal release cycle; the degradation rate was 57.57% after the second cycle; the degradation rate was 63.97% after the third thermal release cycle; the degradation rate was 67.86% after the fourth thermal release cycle, and the degradation rate of V4C3 MXene for tetracycline was 69.2% after five cycles.

[0099] Example 16:

[0100] 50 mg of the V4C3 MXene prepared in Example 4 was weighed and dispersed in a 50 mL beaker containing 20 mg / L tetracycline hydrochloride. A pyroelectrocatalytic experiment on the V4C3 MXene was conducted in the dark under hot and cold cycles between 6 and 35°C. The beaker was first kept at 6°C for 10 minutes, then heated to 35°C over 5 minutes and held for 10 minutes, then cooled back to 6°C over 5 minutes and held for 10 minutes. This cycle was repeated twice, forming a single hot and cold cycle. After each cycle, 3 mL of the suspension was removed from the glass bottle and centrifuged. The absorbance of the dye solution was measured using a UV-visible spectrophotometer. Under dark conditions, the degradation rate of the V4C3 MXene material prepared in Example 1 for 20 mg / L TC was 45.74% after the first thermal release cycle; the degradation rate was 55.91% after the second cycle; the degradation rate was 59.64% after the third thermal release cycle; the degradation rate was 65.85% after the fourth thermal release cycle, and the degradation rate of V4C3 MXene for tetracycline was 68.27% after five cycles.

[0101] The above conclusions and mechanisms are explained in detail below.

[0102] Figure 1 XRD patterns of V4C3 MXene prepared in Examples 1 to 4 of the present invention. After HF etching, a new diffraction characteristic peak appears at 5.3° in the V4C3 MXene material. The diffraction peak intensities of the (004), (008), and (0010) planes corresponding to the hexagonal V4AlC3 with space group P63 / mmc at 15.6°, 31.5°, and 39.7° are significantly reduced. The diffraction peak intensities corresponding to the (104), (105), and (106) planes at 38.9°, 40.8°, and 43.1° are slightly weakened. As the HF etching time increases, the Al atomic layer in V4AlC3 is etched away by HF, and the order of the crystal structure decreases. Therefore, the relative intensity of the diffraction peak at 5.3° increases and gradually broadens, indicating that the V4C3 MXene is successfully etched. When the etching time is 48-72 hours, the diffraction peak at 5.3° for V4C3 gradually shifts to higher angles, which can be attributed to the etching of the Al atomic layer in V4AlC3, resulting in a widening of the interlayer spacing. When the etching time is 96 hours, the diffraction peak at 5.3° gradually shifts to lower angles again. This is because as the reaction time increases, some large V4C3 MXene collapses into smaller multilayer V4C3 MXene, reducing the interlayer spacing. When the etching time is 120 hours, the diffraction peak at 5.3° for V4C3 disappears. This is because the reaction time is too long, and the large V4C3 MXene collapses into smaller two-dimensional or flake V4C3 MXene.

[0103] Figure 2This is an SEM image of the V4C3 MXene prepared in Example 3 of the present invention. After 96 hours of HF etching, the V4AlC3 formed approximately 30 layers of 5μm-thick accordion-like multilayer V4C3 MXene with significant spacing between the layers, preserving the three-dimensional bulk morphology of the V4AlC3.

[0104] Figure 3 and Figure 4 This is the TEM spectrum of V4C3 MXene prepared in Example 3 of the present invention. At a scale of 2 μm, the layered morphology of V4C3 MXene can be clearly seen, and the 0.231 nm and 0.2462 nm lattice fringes correspond to the (104) and (102) crystal planes of V4C3 MXene. It can be concluded that V4C3 MXene material was successfully obtained after HF etching.

[0105] Figure 5 This is the absorbance curve of the V4C3 MXene material prepared in Example 3 of the present invention for 40 mg / L methylene blue under dark conditions. The electron concentration stored in the V4C3 MXene within 24 hours of etching can be calculated from the methylene blue absorbance curve to be 107.83 μmol·g -1 , proving that the V4C3Mxene prepared by the present invention stores electrons.

[0106] Figure 6 This is the absorbance curve of the V4C3 MXene material prepared in Comparative Example 1 of the present invention for 20 mg / L methylene blue under dark conditions. The electron concentration stored in the V4C3 MXene after etching and leaving it for one week can be calculated from the methylene blue absorbance curve to be 68.9 μmol·g -1 Compared with the electron concentration stored in V4C3MXene within 24 hours of etching, the electron concentration stored in V4C3MXene after one week has decreased significantly, proving that the surface oxidation of V4C3MXene material leads to a decrease in the stored electron concentration.

[0107] Figure 7 The V4C3 MXene material prepared in Example 3 of the present invention is heated under dark conditions for h + The electron paramagnetic resonance spectrum of V4C3 MXene was calculated to be 21.76 μmol·g within 24 h of etching. -1 , further proving that the V4C3 Mxene prepared in the present invention stores holes.

[0108] Figure 8 and Figure 9Figure 3 shows the morphology and phase change of the V4C3 MXene material prepared in Example 3 of the present invention. After applying a deflection voltage of ±10 V, the phase angle of the V4C3 MXene flipped by approximately 180°, demonstrating that the dipole is easily transformed by an external electric field.

[0109] Figure 10 This is the amplitude change diagram of the V4C3 MXene material of Example 3 of the present invention. When a deflection voltage of ±10V is applied, the amplitude change diagram of V4C3MXene shows a typical "butterfly-shaped curve", which produces a strain-electric field hysteresis phenomenon, proving that V4C3MXene has a significant piezoelectric response. The d of V4C3MXene is calculated based on the piezoelectric "butterfly-shaped curve". 33 The value is 1.26nm·V -1 , reflecting piezoelectric properties. The piezoelectric polarization characteristics can induce V4C3 MXene materials to store charges and generate piezoelectric charges when deformed by mechanical stress.

[0110] Figure 11 Figure 3 shows the transient piezoelectric current of the V4C3 MXene materials of Examples 1-4 of the present invention under dark conditions. When shear stress is applied in the dark, the V4C3 MXene materials of Examples 1-4 generate transient piezoelectric currents. When the shear stress is turned off, the transient piezoelectric currents of the V4C3 MXene materials of Examples 1-4 gradually maintain a constant value. This indicates that the transient piezoelectric current of the V4C3 MXene in the dark fluctuates with the switching of low-frequency mechanical stress, indicating that the low-frequency shear stress generated by low-frequency magnetic stirring induces a piezoelectric polarization current response in the V4C3 MXene.

[0111] Figure 12 、 Figure 13 The absorbance curves of the V4C3 MXene material prepared in Example 3 of the present invention for 40 mg / L methylene blue after stirring for 0.5 h and 1 h in the dark are shown respectively. The electron concentration stored in the V4C3 MXene can be calculated to be 112.63 μmol·g based on the methylene blue absorbance curve. -1 and 115.91 μmol·g -1 , which is lower than the electron concentration stored in the unstirred V4C3 MXene (107.83 μmol·g -1 ) increased significantly, and low-frequency stirring mechanical stress can store charges in V4C3 MXene materials, indicating that V4C3 MXene has obvious piezoelectric response characteristics under stress and low-frequency stirring mechanical stress can store charges in V4C3 MXene materials.

[0112] Figure 14 、 Figure 15The absorbance curves of the V4C3 MXene material prepared in Example 3 of the present invention for 40 mg / L methylene blue under dark conditions after one and five hot and cold cycles are shown. The electron concentration stored in the V4C3 MXene after one and five hot and cold cycles can be calculated to be 119.47 μmol·g based on the methylene blue absorbance curves. -1 and 123.89 μmol·g -1 , proving that temperature fluctuations can store charges in V4C3MXene materials, further illustrating that V4C3MXene has obvious piezoelectric-pyroelectric response characteristics caused by temperature changes and that temperature fluctuations can store charges in V4C3MXene materials.

[0113] Figure 16 The degradation performance of the V4C3 MXene materials prepared in Examples 1-4 and Comparative Example 1 of the present invention for 20 mg / L tetracycline hydrochloride is shown. The degradation performance of the V4C3 MXene materials prepared in Examples 1-4 corresponds to that of Examples 9-12, respectively. The degradation performance of the V4C3 MXene material in Comparative Example 1 was tested using the same method as in Examples 9-12. Under dark conditions, the energy storage piezocatalytic and piezocatalytic degradation rates of 20 mg / L TC in 60 min for the V4C3 MXene materials prepared in Examples 1-4 and Comparative Example 1 were 60.77%, 66.12%, 70.63%, 64.19%, and 46.41%, respectively.

[0114] Figure 17 The pyroelectrocatalytic degradation performance of the V4C3 MXene materials prepared in Examples 1-4 of the present invention on 20 mg / L tetracycline hydrochloride was demonstrated. The V4C3 MXene material was added to 20 mg / L tetracycline hydrochloride, and pyroelectrocatalytic experiments were conducted in the dark under hot and cold cycles between 6 and 35°C, i.e., Examples 12-16. Figure 15 The inset shows a single cycle of cooling and heating from 6°C to 35°C. After each cycle, 3 mL of the suspension was removed from the glass bottle and centrifuged, and the absorbance of the dye solution was measured using a UV-visible spectrophotometer. Under dark conditions, the V4C3 MXene materials prepared in Examples 1-4 exhibited pyroelectric energy storage catalytic and pyroelectric electrocatalytic degradation rates of 63.71%, 50.27%, 69.2%, and 68.27% for 20 mg / L TC after five thermal cycles, respectively.

[0115] Figure 18 and Figure 19The following are mass spectra of the pyroelectric degradation of 20 mg / L tetracycline by the catalyst prepared in Example 3 of the present invention after one and five hot and cold cycles in the dark. LC-MS analysis revealed that tetracycline, with a high mass-to-charge ratio of m / z = 445, was converted into small molecules with mass-to-charge ratios of m / z = 218, 114, 64, and 60, further demonstrating that the V4C3 MXene material can degrade tetracycline into CO2, H2O, and small organic molecules through pyroelectric energy storage catalysis and pyroelectric catalysis in the dark, demonstrating its suitability as a pyroelectric catalytic material.

[0116] The above is only one embodiment of the present invention, not all or the only embodiment. Any equivalent transformation of the technical solution of the present invention made by ordinary technicians in this field after reading the specification of the present invention is covered by the claims of the present invention.

Claims

1. A method for degrading organic pollutants using V4C3 MXene materials, characterized in that: The V4C3 MXene material within 24 hours after etching is added to a water body containing organic pollutants. Under dark, stirring and hot and cold temperature difference cycle conditions, the V4C3 MXene material is used to catalyze the degradation of organic pollutants in the water body.

2. The method for degrading organic pollutants using V4C3 MXene material according to claim 1, characterized in that: The temperature range of the hot and cold temperature difference cycle is 6℃~35℃.

3. The method for degrading organic pollutants using V4C3 MXene material according to claim 1, characterized in that: The number of hot and cold temperature difference cycles is 1 to 5 times.

4. The method for degrading organic pollutants using V4C3 MXene material according to claim 1, characterized in that: The stirring time is 0.5 to 1 hour.

5. The method for degrading organic pollutants using V4C3 MXene material according to claim 1, characterized in that: The stirring speed is 800r / min~1200r / min.

6. The method for degrading organic pollutants using V4C3 MXene material according to claim 1, characterized in that: The concentration of the V4C3 MXene material in water is 0.08 to 0.10 g / mL.

7. The method for degrading organic pollutants using V4C3 MXene materials according to claim 1, characterized in that: The preparation method of the V4C3 MXene material includes: Step 1: Disperse V4AlC3 powder in HF solution to form a mixed solution, seal the mixed solution, and then stir at 55-65°C for etching reaction to obtain a multilayer vanadium carbide dispersion; Step 2: The multilayer vanadium carbide dispersion is centrifuged, and the resulting precipitate is washed and dried to obtain V4C3 MXene material.

8. The method for degrading organic pollutants using V4C3 MXene material according to claim 7, characterized in that: The stirring time in step 1 is 48 to 120 hours.

9. The method for degrading organic pollutants using V4C3 MXene materials according to claim 7, characterized in that: The washing in step 2 is specifically as follows: first centrifugation washing with deionized water until the pH value of the obtained supernatant is 6.5-7, and then washing with anhydrous ethanol for multiple times.

10. The method for degrading organic pollutants using V4C3 MXene materials according to claim 1, wherein the organic pollutants are antibiotics or dyes.

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