A method for modifying a MOF-based photocatalytic material

Abstract

The application discloses a kind of MOF-based photocatalytic material preparation modification methods, belong to photocatalytic material technical field.The application is with UiO-66-NH2 as precursor, by in-situ oxygen vacancy defect engineering and Z-type heterostructure combination modification strategy, first using low-temperature plasma treatment in the surface of UiO-66-NH2 Controlled concentration of oxygen vacancy is introduced, then in-situ growth ultrathin g-C3N4 nanosheet by solvothermal method forms the Z-type heterojunction of close contact, finally by atomic layer deposition technology load single atom Pt as cocatalyst.The modified MOF-based photocatalytic material prepared by the application can extend the visible light response range to 650nm, the photo-generated carrier separation efficiency is improved by 3.2 times, the photocatalytic hydrogen evolution rate reaches under simulated sunlight, the degradation efficiency of rhodamine B reaches 99.2% in 60 minutes, and the catalytic activity retention rate is more than 92% after 10 cycles.The application method process is simple, mild condition, can be scaled production, and the material prepared has wide application prospect in energy conversion and environmental management field.

Description

Technical Field

[0001] This invention relates to the field of photocatalytic materials technology, specifically to a method for preparing and modifying metal-organic framework (MOF)-based photocatalytic materials, and particularly to a synergistic modification method combining in-situ oxygen vacancy defect engineering, Z-type heterostructure construction, and single-atom co-catalyst loading. Background Technology

[0002] With the increasing severity of the global energy crisis and environmental pollution, solar-driven photocatalysis technology has received widespread attention as a green and sustainable solution. Metal-organic frameworks (MOFs), due to their advantages such as high specific surface area, tunable pore structure, abundant active sites, and designable optical properties, have shown great application potential in photocatalytic hydrogen evolution, CO2 reduction, and degradation of organic pollutants.

[0003] However, the following key technical problems still exist in the practical application of single MOF-based photocatalytic materials: 1. Narrow light absorption range: Most MOF materials can only absorb ultraviolet light, and their utilization rate of visible light, which accounts for about 45% of the solar energy, is extremely low, which seriously limits the conversion efficiency of solar energy.

[0004] 2. High recombination rate of photogenerated carriers: The recombination rate of photogenerated electron-hole pairs in MOF materials is fast, resulting in a small number of effective carriers that can reach the surface to participate in catalytic reactions, and low quantum efficiency.

[0005] 3. Poor stability: During the photocatalytic reaction, the framework structure of MOF materials is easily affected by photocorrosion and chemical corrosion, resulting in a rapid decline in catalytic activity and poor recyclability.

[0006] 4. Insufficient catalytic active sites: The catalytic active sites of MOF materials are mainly concentrated on the surface and in the pores, and some active sites are wrapped by organic ligands, making it difficult to fully contact the reaction substrate and limiting the further improvement of the catalytic reaction rate.

[0007] To address these issues, researchers have developed various modification methods, including ligand functionalization, metal ion doping, semiconductor composites, defect engineering, and co-catalyst loading. For example, introducing functional groups such as amino groups into MOF ligands can broaden their visible light absorption range; forming heterojunctions with other semiconductor materials can promote the separation of photogenerated carriers; and introducing defects can increase catalytic active sites and modulate the band structure.

[0008] However, most existing technologies employ a single modification strategy, making it difficult to simultaneously address the multiple problems associated with MOF-based photocatalysts. For example, while simple ligand functionalization can broaden the light absorption range, it has limited impact on improving carrier separation efficiency; similarly, simple heterostructure construction can promote carrier separation, but its improvement on the light absorption range is not significant. Furthermore, existing modification methods often suffer from complex processes, stringent conditions, high costs, and difficulties in large-scale production, limiting their practical applications.

[0009] Therefore, developing a synergistic modification method that can simultaneously address multiple issues of MOF-based photocatalytic materials, such as narrow light absorption range, high carrier recombination rate, poor stability, and insufficient active sites, is of great significance for promoting the practical application of MOF-based photocatalytic materials. Summary of the Invention

[0010] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing and modifying MOF-based photocatalytic materials. This method, through a synergistic modification strategy combining in-situ oxygen vacancy defect engineering, Z-type heterostructure construction, and single-atom co-catalyst loading, can simultaneously solve key technical problems of single MOF-based photocatalytic materials, such as narrow light absorption range, high recombination rate of photogenerated carriers, poor stability, and insufficient catalytic active sites, and prepare MOF-based photocatalytic materials with excellent photocatalytic performance and cycle stability.

[0011] To achieve the above objectives, the present invention provides the following technical solution: A method for preparing and modifying MOF-based photocatalytic materials includes the following steps: In the first step, ZrCl4 and 2-aminoterephthalic acid were dissolved in N,N-dimethylformamide at a molar ratio of 1:1. Acetic acid was added as a regulator, and the mixture was stirred evenly and then transferred to a reaction vessel. The reaction was carried out at 120°C to 150°C for 12 to 24 hours. After cooling to room temperature, the mixture was centrifuged, washed, and vacuum dried to obtain UiO-66-NH2 powder. The second step involves placing the UiO-66-NH2 powder in a plasma reactor and subjecting it to low-temperature plasma treatment under an argon atmosphere to obtain UiO-66-NH2-Vo powder containing oxygen vacancy defects. The third step involves dispersing UiO-66-NH2-Vo powder in deionized water, adding melamine, ultrasonically treating the mixture, transferring it to a reaction vessel, and reacting it at 180°C to 220°C for 4 to 8 hours. After cooling to room temperature, the mixture is centrifuged, washed, and vacuum dried to obtain the UiO-66-NH2-Vo / g-C3N4 composite photocatalytic material. The fourth step involves placing the UiO-66-NH2-Vo / g-C3N4 composite photocatalyst in an atomic layer deposition reactor and performing atomic layer deposition using dimethylcyclopentadienylplatinum as a precursor to obtain Pt single-atom-supported UiO-66-NH2-Vo / g-C3N4 composite photocatalyst.

[0012] Furthermore, the amount of acetic acid added in the first step is 10 to 20 times the molar amount of ZrCl4.

[0013] Furthermore, the washing in the first step involves washing 3 to 5 times with N,N-dimethylformamide and anhydrous ethanol, respectively, and the vacuum drying is performed at 60 to 80 degrees Celsius for 12 to 24 hours.

[0014] Furthermore, the power of the low-temperature plasma treatment in the second step is 50 watts to 200 watts, and the treatment time is 5 minutes to 30 minutes.

[0015] Furthermore, the power of the low-temperature plasma treatment in the second step is 100 watts to 150 watts, and the treatment time is 10 minutes to 20 minutes.

[0016] Furthermore, in the third step, the mass ratio of UiO-66-NH2-Vo to melamine is 1:5 to 1:20.

[0017] Furthermore, the duration of the ultrasound treatment described in the third step is 30 to 60 minutes.

[0018] Furthermore, the atomic layer deposition temperature described in step four is 150 to 200 degrees Celsius, and the deposition cycle number is 5 to 20 times.

[0019] Furthermore, the atomic layer deposition temperature described in step four is 160 to 180 degrees Celsius, and the deposition cycle number is 8 to 15 times.

[0020] The application of a MOF-based photocatalytic material prepared by the method according to any one of claims 1 to 9 in photocatalytic hydrogen evolution and degradation of organic pollutants.

[0021] Compared with the prior art, the present invention has the following beneficial effects: 1. Significant Synergistic Modification Effect: This invention employs a synergistic modification strategy combining in-situ oxygen vacancy defect engineering, Z-shaped heterostructure construction, and single-atom co-catalyst loading, which can simultaneously solve multiple problems existing in single MOF-based photocatalytic materials. Oxygen vacancy defects can not only broaden the light absorption range but also act as electron traps to promote carrier separation; the Z-shaped heterostructure can achieve efficient separation and transfer of photogenerated carriers while retaining strong redox capabilities; the single-atom Pt co-catalyst can provide abundant catalytic active sites, accelerating surface catalytic reactions.

[0022] 2. Excellent photocatalytic performance: The modified MOF-based photocatalytic material prepared in this invention extends the visible light response range to 650 nm, improves the photogenerated carrier separation efficiency by 3.2 times, and achieves a photocatalytic hydrogen evolution rate of 1286 μmol·g under simulated sunlight. -1 ・h -1 It is 15.6 times that of pure UiO-66-NH2; the degradation efficiency of Rhodamine B reaches 99.2% within 60 minutes, which is 8.3 times that of pure UiO-66-NH2.

[0023] 3. Excellent Cyclic Stability: After 10 cycles, the modified MOF-based photocatalytic material prepared in this invention maintained a photocatalytic hydrogen evolution rate and Rhodamine B degradation efficiency of over 92%, demonstrating excellent cyclic stability. This is mainly attributed to the formation of the Z-type heterojunction and the loading of single-atom co-catalysts, which effectively suppressed photocorrosion and chemical corrosion of the MOF material.

[0024] 4. Simple process and scalable production: The low-temperature plasma treatment, solvothermal method and atomic layer deposition technology used in the method of this invention are all mature industrial technologies. The process is simple, the conditions are mild and easy to control, and it is suitable for large-scale industrial production. Attached Figure Description

[0025] Figure 1 Flowchart of MOF-based photocatalytic material preparation and modification method; Figure 2 Schematic diagram of the core structure of the modified MOF-based photocatalytic material; Figure 3 Schematic diagram of the synergistic modification photocatalytic reaction mechanism. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0027] This invention proposes a method for preparing and modifying MOF-based photocatalytic materials, comprising the following steps: Step 1: Preparation of UiO-66-NH2 precursor: ZrCl4 and 2-aminoterephthalic acid were dissolved in N,N-dimethylformamide at a molar ratio of 1:1. Acetic acid was added as a regulator. After stirring evenly, the mixture was transferred to a reaction vessel and reacted at 120-150℃ for 12-24 hours. After cooling to room temperature, the mixture was centrifuged and washed 3-5 times with N,N-dimethylformamide and anhydrous ethanol, respectively. The mixture was then vacuum dried at 60-80℃ for 12-24 hours to obtain UiO-66-NH2 powder. Step 2: In-situ oxygen vacancy defect engineering: The UiO-66-NH2 powder prepared in step 1 is placed in a plasma reactor and subjected to low-temperature plasma treatment under an argon atmosphere. The treatment power is 50-200W and the treatment time is 5-30 minutes to obtain UiO-66-NH2-Vo powder containing oxygen vacancy defects. Step 3: Z-type heterostructure construction: The UiO-66-NH2-Vo powder prepared in step 2 was dispersed in deionized water, melamine was added, and the mixture was ultrasonically treated for 30-60 minutes to ensure uniform dispersion. Then, it was transferred to a reaction vessel and reacted at 180-220℃ for 4-8 hours. After cooling to room temperature, it was centrifuged and washed 3-5 times with deionized water and anhydrous ethanol, respectively. It was then vacuum dried at 60-80℃ for 12-24 hours to obtain the UiO-66-NH2-Vo / g-C3N4 composite photocatalytic material. Step 4: Single-atom co-catalyst loading: The UiO-66-NH2-Vo / g-C3N4 composite photocatalyst material prepared in step 3 was placed in an atomic layer deposition reactor, and atomic layer deposition was performed at 150-200℃ using di(methylcyclopentadienyl)platinum as a precursor. The deposition cycle was 5-20 times to obtain the Pt single-atom-supported UiO-66-NH2-Vo / g-C3N4 composite photocatalyst material.

[0028] Furthermore, in step 1, the molar ratio of ZrCl4 to 2-aminoterephthalic acid is 1:1, and the amount of acetic acid added is 10-20 times the molar amount of ZrCl4.

[0029] Furthermore, the plasma treatment in step 2 has a power of 100-150W and a treatment time of 10-20 minutes.

[0030] Furthermore, the mass ratio of UiO-66-NH2-Vo to melamine in step 3 is 1:5 to 1:20.

[0031] Furthermore, the atomic layer deposition temperature in step 4 is 160-180℃, and the deposition cycle is 8-15 times.

[0032] The present invention will be further described in detail below with reference to specific embodiments.

[0033] Example 1: A method for preparing and modifying MOF-based photocatalytic materials includes the following steps: 1 mmol ZrCl4 and 1 mmol 2-aminoterephthalic acid were dissolved in 40 mL N,N-dimethylformamide, and 15 mmol acetic acid was added as a regulator. After stirring evenly, the mixture was transferred to a 50 mL polytetrafluoroethylene-lined reactor and reacted at 120 °C for 24 hours. After cooling to room temperature, the mixture was centrifuged and washed three times with N,N-dimethylformamide and anhydrous ethanol, respectively. The mixture was then vacuum dried at 60 °C for 24 hours to obtain UiO-66-NH2 powder. 0.5g of UiO-66-NH2 powder was placed in a plasma reactor and subjected to low-temperature plasma treatment under an argon atmosphere. The treatment power was 100W and the treatment time was 15 minutes to obtain UiO-66-NH2-Vo powder containing oxygen vacancy defects. 0.2g of UiO-66-NH2-Vo powder was dispersed in 40mL of deionized water, and 2g of melamine was added. The mixture was ultrasonically treated for 30 minutes to ensure uniform dispersion. Then, it was transferred to a 50mL polytetrafluoroethylene-lined reactor and reacted at 200℃ for 6 hours. After cooling to room temperature, it was centrifuged and washed three times with deionized water and anhydrous ethanol, respectively. The mixture was then vacuum dried at 60℃ for 24 hours to obtain the UiO-66-NH2-Vo / g-C3N4 composite photocatalytic material. 0.1 g of UiO-66-NH2-Vo / g-C3N4 composite photocatalyst was placed in an atomic layer deposition reactor, and atomic layer deposition was performed at 170 °C using di(methylcyclopentadienyl)platinum as a precursor. The deposition cycle was 10 times to obtain Pt single-atom supported UiO-66-NH2-Vo / g-C3N4 composite photocatalyst.

[0034] Example 2: A method for preparing and modifying MOF-based photocatalytic materials includes the following steps: 1 mmol ZrCl4 and 1 mmol 2-aminoterephthalic acid were dissolved in 40 mL N,N-dimethylformamide, and 10 mmol acetic acid was added as a regulator. After stirring evenly, the mixture was transferred to a 50 mL polytetrafluoroethylene-lined reactor and reacted at 130 °C for 20 hours. After cooling to room temperature, the mixture was centrifuged and washed four times with N,N-dimethylformamide and anhydrous ethanol, respectively. The mixture was then vacuum dried at 70 °C for 18 hours to obtain UiO-66-NH2 powder. 0.5g of UiO-66-NH2 powder was placed in a plasma reactor and subjected to low-temperature plasma treatment under an argon atmosphere. The treatment power was 150W and the treatment time was 10 minutes to obtain UiO-66-NH2-Vo powder containing oxygen vacancy defects. 0.2 g of UiO-66-NH2-Vo powder was dispersed in 40 mL of deionized water, and 1.5 g of melamine was added. The mixture was sonicated for 45 minutes to ensure uniform dispersion. Then, it was transferred to a 50 mL polytetrafluoroethylene-lined reactor and reacted at 190 °C for 7 hours. After cooling to room temperature, the mixture was centrifuged and washed four times with deionized water and anhydrous ethanol, respectively. The mixture was then vacuum dried at 70 °C for 18 hours to obtain the UiO-66-NH2-Vo / g-C3N4 composite photocatalytic material. 0.1 g of UiO-66-NH2-Vo / g-C3N4 composite photocatalyst was placed in an atomic layer deposition reactor, and atomic layer deposition was performed at 160 °C using di(methylcyclopentadienyl)platinum as a precursor. The deposition cycle was 12 times to obtain Pt single-atom supported UiO-66-NH2-Vo / g-C3N4 composite photocatalyst.

[0035] Example 3: A method for preparing and modifying MOF-based photocatalytic materials includes the following steps: 1 mmol ZrCl4 and 1 mmol 2-aminoterephthalic acid were dissolved in 40 mL N,N-dimethylformamide, and 20 mmol acetic acid was added as a regulator. After stirring evenly, the mixture was transferred to a 50 mL polytetrafluoroethylene-lined reactor and reacted at 140 °C for 16 hours. After cooling to room temperature, the mixture was centrifuged and washed 5 times each with N,N-dimethylformamide and anhydrous ethanol. The mixture was then vacuum dried at 80 °C for 12 hours to obtain UiO-66-NH2 powder. 0.5g of UiO-66-NH2 powder was placed in a plasma reactor and subjected to low-temperature plasma treatment under an argon atmosphere. The treatment power was 50W and the treatment time was 30 minutes to obtain UiO-66-NH2-Vo powder containing oxygen vacancy defects. 0.2 g of UiO-66-NH2-Vo powder was dispersed in 40 mL of deionized water, and 3 g of melamine was added. The mixture was ultrasonically treated for 60 minutes to ensure uniform dispersion. Then, it was transferred to a 50 mL polytetrafluoroethylene-lined reactor and reacted at 210 °C for 5 hours. After cooling to room temperature, it was centrifuged and washed 5 times with deionized water and anhydrous ethanol, respectively. The mixture was then vacuum dried at 80 °C for 12 hours to obtain the UiO-66-NH2-Vo / g-C3N4 composite photocatalytic material. 0.1 g of UiO-66-NH2-Vo / g-C3N4 composite photocatalyst was placed in an atomic layer deposition reactor, and atomic layer deposition was performed at 180 °C using di(methylcyclopentadienyl)platinum as a precursor. The deposition cycle was 8 times to obtain Pt single-atom supported UiO-66-NH2-Vo / g-C3N4 composite photocatalyst.

[0036] Comparative Example 1: Pure UiO-66-NH2 photocatalyst material was prepared according to the method in step 1 of Example 1.

[0037] Comparative Example 2: The UiO-66-NH2-Vo photocatalytic material was prepared according to steps 1 and 2 of Example 1.

[0038] Comparative Example 3: The UiO-66-NH2 / g-C3N4 composite photocatalyst material was prepared according to steps 1 and 3 of Example 1, omitting the plasma treatment in step 2.

[0039] Performance testing: (a) Photocatalytic hydrogen evolution performance test The Labsolar-6A all-glass automated online photocatalytic reaction system manufactured by Beijing Pofilai Technology Co., Ltd. was used for testing. The light source was a 300W xenon lamp equipped with an AM 1.5G filter, simulating standard sunlight irradiation. The light intensity was calibrated to 100mW·cm using a power meter. -2 The reaction system consisted of 100 mL of deionized water and 10 mL of triethanolamine, with triethanolamine acting as a hole sacrificial agent. The catalyst was precisely weighed at 20 mg. Before the reaction, the system was sealed and evacuated for 30 minutes using a mechanical vacuum pump to completely remove air and ensure no oxygen interference. Then, the magnetic stirrer and circulating cooling water system were activated to maintain the reaction temperature at 25 ± 1 °C, and the light source was turned on for photocatalytic reaction. During the reaction, samples were automatically taken every hour, and the amount of hydrogen produced was detected using a gas chromatograph equipped with a thermal conductivity detector. The carrier gas was high-purity argon, and the flow rate was 30 mL / min. -1 The chromatographic column was a 5A molecular sieve column, and the column temperature was 80℃. The quantification of hydrogen was carried out using the external standard method, and the actual hydrogen production was calculated by plotting a standard curve of standard hydrogen concentration versus peak area.

[0040] (II) Performance test of photocatalytic degradation of organic pollutants Using Rhodamine B as a typical cationic organic pollutant model, the initial concentration was precisely prepared to be 10 mg / L; 20 mg of catalyst was accurately weighed and added to 100 mL of Rhodamine B solution to form a suspension system; before the reaction, it was carried out under dark conditions at 300 r·min -1 The catalyst was magnetically stirred at a certain speed for 30 minutes to allow the catalyst and pollutants to reach adsorption-desorption equilibrium. A sample was taken at this point as the initial concentration C0. Then, a 300W xenon lamp equipped with an AM 1.5G filter was turned on for photoreaction, with the light intensity also calibrated to 100mW·cm². -2 During the reaction, take a 5 mL sample every 10 minutes and immediately spray at 8000 r·min. -1 Centrifuge at a certain speed for 5 minutes, collect the supernatant, and measure the absorbance of Rhodamine B at a wavelength of 554 nm using a Shimadzu UV-2600 UV-Vis spectrophotometer. According to the Lambert-Beer law, absorbance is linearly related to concentration. The pollutant concentration C at different time points was calculated using a standard curve. t The formula for calculating degradation efficiency is: Degradation efficiency (%) = (1-C) t / C0)×100%.

[0041] (III) Cyclic stability test To evaluate the material's practical application potential, 10 consecutive cyclic photocatalytic experiments were conducted; after each reaction, the reaction system was accelerated at 10000 r·min. -1 The catalyst was centrifuged at a certain speed for 10 minutes to collect the precipitated catalyst. It was then washed three times each with deionized water and anhydrous ethanol to thoroughly remove residual contaminants and sacrificial agents adsorbed on the catalyst surface. The catalyst was then dried in a vacuum drying oven at 60°C for 12 hours to completely remove the solvent. The next cycle experiment was conducted under the exact same conditions as the first experiment. The reaction solution was prepared fresh for each cycle to ensure consistent reaction conditions. After the cycle experiment, the photocatalytic hydrogen evolution rate and Rhodamine B degradation efficiency were calculated for each cycle. The activity retention rate after 10 cycles was calculated with the activity of the first experiment as 100%. At the same time, the catalyst after the cycle was characterized by X-ray diffraction and scanning electron microscopy to analyze the changes in its crystal structure and microstructure, further verifying the structural stability of the material.

[0042] Test Results The photocatalytic performance test results of each embodiment and comparative example are shown in the table below: The test results show that the modified MOF-based photocatalytic material prepared in this embodiment of the invention has a significantly higher photocatalytic hydrogen evolution rate and Rhodamine B degradation efficiency than the comparative example, and exhibits excellent cycle stability.

[0043] In Example 1, the photocatalytic hydrogen evolution rate reached 1286 μmol·g. -1 ・h -1 The degradation efficiency of UiO-66-NH2 was 15.6 times that of pure UiO-66-NH2, 5.9 times that of UiO-66-NH2-Vo modified only by oxygen vacancies, and 2.8 times that of the UiO-66-NH2 / g-C3N4 binary composite material without oxygen vacancies. The degradation efficiency of Rhodamine B reached 99.2% within 60 minutes, which was 8.3 times, 2.8 times, and 1.5 times that of the three comparative examples mentioned above. This result clearly shows that a single modification strategy can only partially improve one aspect of the performance of MOF-based photocatalytic materials, while this invention organically combines three modification methods to achieve a synergistic leap in performance.

[0044] Oxygen vacancy defect engineering not only broadened the visible light response range of the material but also provided abundant nucleation sites for the in-situ growth of g-C3N4 nanosheets, enabling the two to form an atomically close interface and significantly reducing carrier transfer resistance. The construction of the Z-type heterojunction achieved efficient spatial separation of photogenerated carriers while fully preserving the strong redox capabilities of both components. The uniform loading of single-atom Pt cocatalyst further provided a high density of hydrogen evolution active sites, accelerating surface reaction kinetics. These three elements worked together to systematically optimize the entire chain from light absorption and carrier separation to surface catalytic reaction.

[0045] Regarding cycle stability, the material of this invention retains over 92% of its activity after 10 cycles, significantly higher than the 45.2% retention rate of pure UiO-66-NH2. This is because the charge transfer mechanism of the Z-type heterojunction primarily enriches the highly oxidizing holes on the g-C3N4 surface, effectively preventing photocorrosion of the MOF framework. Furthermore, the anchoring effect of single-atom Pt further enhances the structural stability of the material. This demonstrates that the synergistic modification strategy employed in this invention can simultaneously address multiple core issues in MOF-based photocatalytic materials, providing a new technological pathway for the development of high-performance photocatalytic materials.

[0046] The above embodiments are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications or equivalent substitutions based on the technical solutions of the present invention without departing from the core ideas of the present invention shall fall within the protection scope of the present invention.

Claims

1. A method for preparing and modifying MOF-based photocatalytic materials, characterized in that, Includes the following steps: In the first step, ZrCl4 and 2-aminoterephthalic acid were dissolved in N,N-dimethylformamide at a molar ratio of 1:

1. Acetic acid was added as a regulator, and the mixture was stirred evenly and then transferred to a reaction vessel. The reaction was carried out at 120°C to 150°C for 12 to 24 hours. After cooling to room temperature, the mixture was centrifuged, washed, and vacuum dried to obtain UiO-66-NH2 powder. The second step involves placing the UiO-66-NH2 powder in a plasma reactor and subjecting it to low-temperature plasma treatment under an argon atmosphere to obtain UiO-66-NH2-Vo powder containing oxygen vacancy defects. The third step involves dispersing UiO-66-NH2-Vo powder in deionized water, adding melamine, ultrasonically treating the mixture, transferring it to a reaction vessel, and reacting it at 180°C to 220°C for 4 to 8 hours. After cooling to room temperature, the mixture is centrifuged, washed, and vacuum dried to obtain the UiO-66-NH2-Vo / g-C3N4 composite photocatalytic material. The fourth step involves placing the UiO-66-NH2-Vo / g-C3N4 composite photocatalyst in an atomic layer deposition reactor and performing atomic layer deposition using dimethylcyclopentadienylplatinum as a precursor to obtain Pt single-atom-supported UiO-66-NH2-Vo / g-C3N4 composite photocatalyst.

2. The method for preparing and modifying MOF-based photocatalytic materials according to claim 1, characterized in that, The amount of acetic acid added in the first step is 10 to 20 times the molar amount of ZrCl4.

3. The method for preparing and modifying MOF-based photocatalytic materials according to claim 1, characterized in that, The washing in the first step involves washing 3 to 5 times with N,N-dimethylformamide and anhydrous ethanol, respectively, and the vacuum drying is performed at 60 to 80 degrees Celsius for 12 to 24 hours.

4. The method for preparing and modifying MOF-based photocatalytic materials according to claim 1, characterized in that, The power of the low-temperature plasma treatment in the second step is 50 watts to 200 watts, and the treatment time is 5 minutes to 30 minutes.

5. The method for preparing and modifying MOF-based photocatalytic materials according to claim 4, characterized in that, The low-temperature plasma treatment in the second step has a power of 100 to 150 watts and a treatment time of 10 to 20 minutes.

6. The method for preparing and modifying MOF-based photocatalytic materials according to claim 1, characterized in that, In the third step, the mass ratio of UiO-66-NH2-Vo to melamine is 1:5 to 1:

20.

7. The method for preparing and modifying MOF-based photocatalytic materials according to claim 1, characterized in that, The ultrasound treatment in the third step lasts for 30 to 60 minutes.

8. The method for preparing and modifying MOF-based photocatalytic materials according to claim 1, characterized in that, The atomic layer deposition temperature described in step four is 150 to 200 degrees Celsius, and the deposition cycle is 5 to 20 times.

9. The method for preparing and modifying MOF-based photocatalytic materials according to claim 8, characterized in that, The atomic layer deposition temperature described in step four is 160 to 180 degrees Celsius, and the deposition cycle is 8 to 15 times.

10. The application of a MOF-based photocatalytic material prepared by the method according to any one of claims 1 to 9 in photocatalytic hydrogen evolution and degradation of organic pollutants.

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