A preparation method of micron-sized electrically polarized MOFs composite material

Abstract

The present invention discloses a method for preparing a micron-sized electrically polarized MOF composite material. First, tourmaline is dissolved in a ZrCl4 solution, and the pH value of the solution is adjusted. TM-ZrO2 powder is then prepared through stirring, ultrasonication, aging, and calcination processes. TM-ZrO2 powder is added to a precursor solution required for synthesizing MOF, subjected to a programmed temperature reaction, and then subjected to processes such as centrifugation, washing, and drying to obtain TM-ZrO2@NU66 powder. The method of the present invention composites micron-sized spontaneously polarized tourmaline with MOF, effectively reducing the compatibility of particles of the MOF composite material at the nanoscale while improving the electron transmission capacity, light absorption capacity, and separation capacity of photogenerated electrons and holes of the MOF composite material, providing a new perspective for the efficient degradation of VOCs by MOF functional composite materials.

Description

Technical Field

[0001] The present invention belongs to the technical field of novel functional materials, and in particular relates to a method for preparing a micron-sized electrically polarized MOFs composite material. Background Art

[0002] Tourmaline, as a green and economical natural borosilicate mineral, produces an electric dipole due to the mismatch of its positive and negative charges, thus exhibiting permanent spontaneous polarization, pyroelectricity and the release of negative oxygen ions. 6 ~10 7 VM -1 A strong electrostatic field. Studies have shown that tourmaline can establish a long-range, ordered electric field through the driving force of spontaneous polarization, effectively promoting carrier migration and achieving carrier separation. Currently, tourmaline is widely used in pollutant removal, medical treatment, photocatalysis, and other fields.

[0003] Metal-organic frameworks (MOFs), as periodic, hybrid, and porous crystalline materials, have been extensively studied in the field of photocatalytic reactions due to their ultrahigh porosity, well-dispersed spatially arranged active sites, low density, and tunable functionality. However, their catalytic efficiency is severely limited by the poor charge separation and slow charge transfer kinetics caused by the rapid recombination of photogenerated electrons and holes. To date, various strategies have been developed to reduce the recombination rate of photoinduced carriers and the charge transfer problem. However, due to the lack of rich nanoscale interfaces, the application of functional combination methods to promote photogenerated charge separation in MOFs is limited by the material particle size mismatch problem.

[0004] How to make a large number of MOFs grow firmly and evenly on the tourmaline surface, and effectively improve the catalytic performance of MOF composite materials while reducing the compatibility of MOF composite materials at the nanoscale is a difficult problem in current research. Summary of the Invention

[0005] To address the technical challenges of effectively reducing the compatibility of nanoscale particles in MOF composites, constructing micrometer-scale interfaces, and improving the catalytic performance of MOF composites, the present invention provides a method for preparing micro-interface electrically polarized MOF composites. This method utilizes a step-by-step synthesis method to pre-grow a homologous metal oxide on a tourmaline surface. The homologous metal oxide is loaded onto the tourmaline surface using a sol-gel method, and the homologous MOF is epitaxially grown on the oxide surface using a conventional hydrothermal method, resulting in a micrometer-scale electrically polarized MOF composite.

[0006] The results of the present invention are achieved through the following technical solutions:

[0007] A method for preparing a micron-sized electrically polarized MOF composite material comprises the following steps:

[0008] (1) Preparation of tourmaline-homologous metal oxides;

[0009] A certain amount of tourmaline powder is added to the ZrCl4 solution, stirred evenly, and the pH of the solution is adjusted to 6-11. The solution is stirred and ultrasonicated for 1-9 hours, and then allowed to stand to obtain a colloidal precipitate. The colloidal precipitate is then filtered, washed with water until neutral, and air-dried. Finally, the solution is calcined at 200-600°C for 2-8 hours. After the reaction is completed, the solution is cooled to room temperature to obtain a tourmaline-homologous metal oxide composite powder, which is designated as TM-ZrO2.

[0010] (2) Preparation of micron-scale electrodeposited MOF composites;

[0011] Anhydrous zirconium chloride ZrCl4 is dissolved in water, and then 5 to 50 wt.% of tourmaline-homologous metal oxide composite powder TM-ZrO2 is added and stirred evenly, which is marked as solution A; 2-aminoterephthalic acid solution is then added to solution A and stirred evenly, and then trifluoroacetic acid is added to the mixture as a crystal modifier. After mixing, the mixture is transferred to the lining of a reactor, and the reactor is placed in a forced air drying oven and reacted at 80 to 150°C for 4 to 24 hours. After the reaction, it is naturally cooled to room temperature, centrifuged, washed and dried to obtain a micron-sized electrically polarized MOF composite material of MOF and tourmaline (denoted as: TM-ZrO2@NU66).

[0012] As a further preferred embodiment of the present technical solution, the preparation of the ZrCl4 solution in step (1) is to dissolve anhydrous ZrCl4 in water to obtain a ZrCl4 solution with a concentration of 0.1 to 0.5 mol / L.

[0013] As a further preferred embodiment of the present technical solution, the amount of tourmaline added in step (1) is 5 to 200 wt.% of the mass of anhydrous ZrCl4, and the particle size of the tourmaline is 500 mesh to 2000 mesh.

[0014] As a further preferred embodiment of the present technical solution, in step (1), NH3·H2O solution is used to adjust the pH value.

[0015] As a further preferred embodiment of the present technical solution, in step (1), the mixture is first stirred for 1 to 6 hours, then ultrasonicated for 0.5 to 3 hours, and then allowed to stand for 1 to 12 hours.

[0016] As a further preferred embodiment of the present technical solution, in step (2), the molar ratio of anhydrous zirconium chloride to 2-aminoterephthalic acid in solution A is 1:1.1 to 1.9.

[0017] As a further preferred embodiment of the present technical solution, after the 2-aminoterephthalic acid solution is added to solution A in step (1), the stirring time is 5 minutes to 2 hours.

[0018] As a further preferred embodiment of the present technical solution, the volume ratio of trifluoroacetic acid added in step (2) to solution A is 6 to 15:20.

[0019] As a further preferred embodiment of the present technical solution, the temperature increase in step (2) can be carried out using a program-controlled blast drying oven, and the specific reaction process is as follows:

[0020] (a) Heating stage: heating to 80-150°C at a heating rate of 0.5-5°C / min;

[0021] (b) Constant temperature stage: keep at 80-150℃ for 4-24h.

[0022] The resistance of the micron-sized electrically polarized MOF composite material can be controlled below 88.8Ω.

[0023] The technical principle of the present invention is as follows: first, the homologous metal oxide is pre-loaded onto the surface of tourmaline as an intermediate transition layer between tourmaline and MOF, and then the metal on the homologous metal is used as a partial metal source to epitaxially grow MOF, ultimately forming a micron-scale electrically polarized MOF material in which the tourmaline and MOF are tightly connected.

[0024] The micron-sized electrically polarized MOF composite prepared by the present invention demonstrates a large amount of MOF firmly and evenly grown on the tourmaline surface as seen in SEM images, and the composite material exhibits excellent photoelectric properties. DRS and EIS characterizations reveal enhanced electron transport performance, a red-shifted absorption edge, and enhanced light absorption. Due to the spontaneous polarization effect of tourmaline, the composite's internal electric field is regulated. Once charges are generated in the composite, they migrate to the composite's surface at an accelerated rate, driven by the tourmaline's spontaneous polarization field. This improves migration efficiency and, as a result, the MOF composite exhibits superior charge transfer capabilities.

[0025] The product of the present invention is applied in the field of photocatalytic degradation of gaseous aldehyde VOCs. Due to the driving force of spontaneous polarization of tourmaline, the migration rate of photogenerated carriers in MOF is significantly accelerated, and the separation ability of photogenerated electrons and holes is significantly enhanced, thereby effectively improving the photocatalytic performance of the composite material.

[0026] Compared with the prior art, the advantages of the present invention are:

[0027] (1) The pH value of the tourmaline-homologous metal oxide preparation process of the present invention is controlled at 6 to 11, because the pH value is different, the Zr 4+The different rates of ion hydrolysis to zirconium hydroxide further affect the uniformity of the loading of homologous metal oxides on the tourmaline surface.

[0028] (2) The present invention can effectively reduce the compatibility of particles of the MOF composite material at the nanoscale, so a large amount of MOF grows firmly and evenly on the tourmaline surface, and the prepared micron-scale electrically polarized MOF composite material has a tight interface.

[0029] (3) The present invention combines tourmaline with MOF to form a long-range ordered electric field around the MOF, thereby increasing the composite's electron transport capacity. The resistance of the micron-sized electrically polarized MOF composite (TM-ZrO2@NU66) is 88.8Ω, a 2.77-fold decrease compared to the 334.7Ω resistance of the conventional MOF (NU66), indicating a significant reduction in resistance and demonstrating a significant enhancement in the composite's electron transport capacity.

[0030] (4) Driven by the self-polarization of tourmaline, the photogenerated electrons and holes generated by MOF are effectively separated, greatly improving the carrier utilization rate.

[0031] (5) The absorption edge of the product of the present invention is red-shifted, the light absorption capacity is enhanced, and the light utilization rate is effectively improved.

[0032] (6) The amount of tourmaline added in the present invention should be controlled within the range of 5 to 50 wt.%. This is because increasing the amount of TM-ZrO2 further improves the uniform coverage of NU66 and exposes more catalytic sites, thereby enhancing its catalytic activity. However, excessive addition of TM-ZrO2 can lead to TM-ZrO2 accumulation, which reduces its photoelectric performance and, in turn, its catalytic ability to degrade formaldehyde. When the amount of tourmaline added is 20 wt.%, the catalytic efficiency reaches 90.02%.

[0033] (7) The product of the present invention can be applied to the field of photocatalytic degradation technology. After photocatalysis of formaldehyde, the degradation efficiency reaches more than 90%, effectively improving the photocatalytic degradation performance of gaseous formaldehyde. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 SEM images of TM-ZrO2@NU66 and traditional MOF (NU66).

[0035] Figure 2 This is the AC impedance diagram of TM-ZrO2@NU66 and traditional MOF (NU66).

[0036] Figure 3 DRS spectra of TM-ZrO2@NU66 and traditional MOF (NU66).

[0037] Figure 4 PL spectra of TM-ZrO2@NU66 and traditional MOF (NU66).

[0038] Figure 5 This is a diagram showing the photocatalytic degradation performance of TM-ZrO2@NU66, traditional MOF (NU66) and pure tourmaline (TM) for gaseous formaldehyde.

[0039] Figure 6 This is a diagram showing the photocatalytic degradation performance of gaseous formaldehyde with different TM-ZrO2 doping amounts in the prepared TM-ZrO2@NU66. DETAILED DESCRIPTION

[0040] The present invention will be further described below with reference to the accompanying drawings and embodiments, but the scope of protection claimed by the present invention is not limited to the scope of protection of the embodiments.

[0041] Example 1

[0042] A method for preparing a micron-sized electrically polarized MOF composite material comprises the following steps:

[0043] (1) Preparation of tourmaline-homologous metal oxides;

[0044] A 0.1 mol / L ZrCl₄ solution was prepared by dissolving a certain amount of ZrCl₄ in deionized water. A 5 wt.% (500 mesh) amount of tourmaline powder was added to the ZrCl₄ solution relative to the mass of anhydrous ZrCl₄ added and stirred uniformly. An NH₃·H₂O solution was then slowly added dropwise to the vigorously stirred mixed solution until the pH reached 6. Stirring was continued at room temperature for 1 hour, followed by ultrasonication for 0.5 hours. Finally, the solution was allowed to stand at room temperature for 2 hours, yielding a white gelatinous hydroxide precipitate. The resulting white gelatinous precipitate was filtered and repeatedly washed with deionized water until neutral. The solution was then dried in a forced-air dryer at 80°C for 8 hours and calcined at 200°C for 8 hours. After the reaction, the mixture was naturally cooled to room temperature to yield a tourmaline-homologous metal oxide (TM-ZrO₂) composite powder.

[0045] (2) Preparation of micron-scale electrodeposited MOF composites;

[0046] 3 mmol of anhydrous zirconium chloride (ZrCl4) was dissolved in 10 mL of deionized water. After complete dissolution, 5 wt.% TM-ZrO2 (relative to the anhydrous zirconium chloride (ZrCl4)) was added to the mixture, stirred thoroughly, and labeled as Solution A. 3 mmol of 2-aminoterephthalic acid was added to deionized water and dissolved thoroughly, labeled as Solution B. Solution B was slowly added to Solution A and stirred thoroughly. Then, 6 mL of trifluoroacetic acid (TFA) was added to the mixture as a crystal modifier. After thorough mixing, the mixture was transferred to a polytetrafluoroethylene-lined reactor. The reactor was placed in a forced air drying oven and heated from room temperature to 80°C at a rate of 0.5°C / min for 24 hours. After completion of the reaction, the mixture was naturally cooled to room temperature. Subsequently, the mixture was centrifuged, washed, and dried to obtain a micron-sized, electrically polarized MOF composite material (denoted as TM-ZrO2@NU66) powder composed of MOF and tourmaline.

[0047] Example 2

[0048] A method for preparing a micron-sized electrically polarized MOF composite material comprises the following steps:

[0049] (1) Preparation of tourmaline-homologous metal oxides;

[0050] A 0.2 mol / L ZrCl₄ solution was prepared by dissolving a certain amount of ZrCl₄ in deionized water. 20 wt.% of tourmaline (1000 mesh particle size) powder relative to the mass of anhydrous ZrCl₄ was added to the ZrCl₄ solution and stirred uniformly. An NH₃·H₂O solution was then slowly added dropwise to the vigorously stirred mixed solution until the pH reached 8. Stirring was continued at room temperature for 2 hours, followed by ultrasonication for 1 hour, and finally allowed to stand at room temperature for 4 hours, yielding a white gelatinous hydroxide precipitate. The resulting white gelatinous precipitate was filtered and repeatedly washed with deionized water until neutral. It was then dried in a forced-air dryer at 80°C for 8 hours and finally calcined at 300°C for 6 hours. After the reaction, the mixture was naturally cooled to room temperature to yield a tourmaline-homologous metal oxide (TM-ZrO₂) composite powder.

[0051] (2) Preparation of micron-scale electrodeposited MOF composites;

[0052] 3 mmol of anhydrous zirconium chloride (ZrCl4) was dissolved in 10 mL of deionized water. After complete dissolution, 10 wt.% TM-ZrO2 (relative to the anhydrous zirconium chloride (ZrCl4)) was added to the mixture, stirred thoroughly, and labeled as Solution A. 3.5 mmol of 2-aminoterephthalic acid was added to deionized water and dissolved thoroughly, labeled as Solution B. Solution B was slowly added to Solution A and stirred thoroughly. 8 mL of trifluoroacetic acid (TFA) was then added to the mixture as a crystal modifier. After thorough mixing, the mixture was transferred to a polytetrafluoroethylene-lined reactor. The reactor was placed in a forced air drying oven and heated from room temperature to 100°C at a rate of 1°C / min for 15 hours. After completion of the reaction, the mixture was naturally cooled to room temperature. Subsequently, the mixture was centrifuged, washed, and dried to obtain a micron-sized, electrically polarized MOF composite (TM-ZrO2@NU66) powder composed of MOF and tourmaline.

[0053] Example 3

[0054] A method for preparing a micron-sized electrically polarized MOF composite material comprises the following steps:

[0055] (1) Preparation of tourmaline-homologous metal oxides;

[0056] A 0.3 mol / L ZrCl₄ solution was prepared by dissolving a certain amount of ZrCl₄ in deionized water. A 50 wt.% portion of tourmaline (1500 mesh particle size) was added to the ZrCl₄ solution relative to the mass of anhydrous ZrCl₄ added and stirred uniformly. An NH₃·H₂O solution was then slowly added dropwise to the vigorously stirred mixed solution until the pH reached 9. Stirring was continued at room temperature for 3 hours, followed by ultrasonication for 1.5 hours, and finally, the mixture was allowed to stand at room temperature for 6 hours, yielding a white gelatinous hydroxide precipitate. The resulting white gelatinous precipitate was filtered and repeatedly washed with deionized water until neutral. The mixture was then dried in a forced-air dryer at 80°C for 8 hours and calcined at 400°C for 4 hours. After the reaction, the mixture was naturally cooled to room temperature to yield a tourmaline-homologous metal oxide (TM-ZrO₂) composite powder.

[0057] (2) Preparation of micron-scale electrodeposited MOF composites;

[0058] 3 mmol of anhydrous zirconium chloride (ZrCl4) was dissolved in 10 mL of deionized water. Once fully dissolved, 15 wt.% TM-ZrO2 (relative to the anhydrous zirconium chloride (ZrCl4)) was added to the mixture, stirred thoroughly, and labeled as Solution A. 4 mmol of 2-aminoterephthalic acid was added to deionized water and dissolved thoroughly, labeled as Solution B. Solution B was slowly added to Solution A and stirred thoroughly. Then, 10 mL of trifluoroacetic acid (TFA) was added to the mixture as a crystal modifier. After thorough mixing, the mixture was transferred to a polytetrafluoroethylene-lined reactor. The reactor was placed in a forced air drying oven and heated from room temperature to 120°C at a rate of 2°C / min for 12 hours. After the reaction, the mixture was naturally cooled to room temperature. Subsequently, the mixture was centrifuged, washed, and dried to obtain a micron-sized, electrically polarized MOF composite material (denoted as TM-ZrO2@NU66) powder composed of MOF and tourmaline.

[0059] Example 4

[0060] A method for preparing a micron-sized electrically polarized MOF composite material comprises the following steps:

[0061] (1) Preparation of tourmaline-homologous metal oxides;

[0062] A 0.4 mol / L ZrCl₄ solution was prepared by dissolving a certain amount of ZrCl₄ in deionized water. Tourmaline (2000 mesh particle size) powder (100 wt.% relative to the mass of anhydrous ZrCl₄) was added to the ZrCl₄ solution and stirred uniformly. An NH₃·H₂O solution was then slowly added dropwise to the vigorously stirred mixed solution until the pH reached 10. Stirring was continued at room temperature for 5 hours, followed by ultrasonication for 2 hours, and finally, the mixture was allowed to stand at room temperature for 8 hours, yielding a white gelatinous hydroxide precipitate. The resulting white gelatinous precipitate was filtered and repeatedly washed with deionized water until neutral. The mixture was then dried in a forced air dryer at 80°C for 8 hours and calcined at 500°C for 3 hours. After the reaction, the mixture was naturally cooled to room temperature to yield a tourmaline-homologous metal oxide (TM-ZrO₂) composite powder.

[0063] (2) Preparation of micron-scale electrodeposited MOF composites;

[0064] 3 mmol of anhydrous zirconium chloride (ZrCl4) was dissolved in 10 mL of deionized water. After complete dissolution, 20 wt.% TM-ZrO2 (relative to the anhydrous zirconium chloride (ZrCl4)) was added to the mixture, stirred thoroughly, and labeled as Solution A. 4.5 mmol of 2-aminoterephthalic acid was added to deionized water and dissolved thoroughly, labeled as Solution B. Solution B was slowly added to Solution A and stirred thoroughly. Then, 10 mL of trifluoroacetic acid (TFA) was added to the mixture as a crystal modifier. After thorough mixing, the mixture was transferred to a polytetrafluoroethylene-lined reactor. The reactor was placed in a forced air drying oven and heated from room temperature to 130°C at a rate of 3°C / min for 8 hours. After completion of the reaction, the mixture was naturally cooled to room temperature. Subsequently, the mixture was centrifuged, washed, and dried to obtain a micron-sized, electrically polarized MOF composite (TM-ZrO2@NU66) powder composed of MOF and tourmaline.

[0065] Example 5

[0066] A method for preparing a micron-sized electrically polarized MOF composite material comprises the following steps:

[0067] (1) Preparation of tourmaline-homologous metal oxides;

[0068] A 0.5 mol / L ZrCl₄ solution was prepared by dissolving a certain amount of ZrCl₄ in deionized water. 200 wt.% of tourmaline (2000 mesh particle size) powder was added to the ZrCl₄ solution, relative to the mass of anhydrous ZrCl₄ added, and the mixture was stirred uniformly. An NH₃·H₂O solution was then slowly added dropwise to the vigorously stirred mixture until the pH reached 11. The mixture was stirred continuously at room temperature for 6 hours, ultrasonicated for 3 hours, and allowed to stand at room temperature for 12 hours, yielding a white gelatinous hydroxide precipitate. The resulting white gelatinous precipitate was filtered and repeatedly washed with deionized water until neutral. The mixture was then dried in a forced-air dryer at 80°C for 8 hours and calcined at 600°C for 2 hours. After the reaction, the mixture was naturally cooled to room temperature to yield a tourmaline-homologous metal oxide (TM-ZrO₂) composite powder.

[0069] (2) Preparation of micron-scale electrodeposited MOF composites;

[0070] 3 mmol of anhydrous zirconium chloride (ZrCl4) was dissolved in 10 mL of deionized water. After complete dissolution, 30 wt.% TM-ZrO2 (relative to the anhydrous zirconium chloride (ZrCl4)) was added to the mixture, stirred thoroughly, and labeled as Solution A. 5 mmol of 2-aminoterephthalic acid was added to deionized water and dissolved thoroughly, labeled as Solution B. Solution B was slowly added to Solution A and stirred thoroughly. Then, 15 mL of trifluoroacetic acid (TFA) was added to the mixture as a crystal modifier. After thorough mixing, the mixture was transferred to a polytetrafluoroethylene-lined reactor. The reactor was placed in a forced air drying oven and heated from room temperature to 150°C at a rate of 5°C / min for 4 hours. After completion of the reaction, the temperature was naturally cooled to room temperature. Subsequently, the mixture was centrifuged, washed, and dried to obtain a micron-sized, electrically polarized MOF composite (TM-ZrO2@NU66) powder composed of MOF and tourmaline.

[0071] Example 6

[0072] A method for preparing a micron-sized electrically polarized MOF composite material comprises the following steps:

[0073] (1) Preparation of tourmaline-homologous metal oxides;

[0074] A 0.2 mol / L ZrCl₄ solution was prepared by dissolving a certain amount of ZrCl₄ in deionized water. A 50 wt.% (2000 mesh) amount of tourmaline powder was added to the ZrCl₄ solution relative to the mass of anhydrous ZrCl₄ added and stirred uniformly. An NH₃·H₂O solution was then slowly added dropwise to the vigorously stirred mixed solution until the pH reached 10. Stirring was continued at room temperature for 2 hours, followed by ultrasonication for 1 hour, and finally allowed to stand at room temperature for 4 hours, yielding a white gelatinous hydroxide precipitate. The resulting white gelatinous precipitate was filtered and repeatedly washed with deionized water until neutral. The mixture was then dried in a forced-air dryer at 80°C for 8 hours and calcined at 400°C for 4 hours. After the reaction, the mixture was naturally cooled to room temperature to yield a tourmaline-homologous metal oxide (TM-ZrO₂) composite powder.

[0075] (2) Preparation of micron-scale electrodeposited MOF composites;

[0076] 3 mmol of anhydrous zirconium chloride (ZrCl4) was dissolved in 10 mL of deionized water. Once fully dissolved, 20 wt.% TM-ZrO2 (relative to the anhydrous zirconium chloride (ZrCl4)) was added to the mixture, stirred thoroughly, and labeled as Solution A. 4.5 mmol of 2-aminoterephthalic acid was added to deionized water and dissolved thoroughly, labeled as Solution B. Solution B was slowly added to Solution A and stirred thoroughly. 8 mL of trifluoroacetic acid (TFA) was then added to the mixture as a crystal modifier. After thorough mixing, the mixture was transferred to a polytetrafluoroethylene-lined reactor. The reactor was placed in a forced air drying oven and heated from room temperature to 100°C at a rate of 1°C / min for 6 hours. After the reaction, the mixture was naturally cooled to room temperature. Subsequently, the mixture was centrifuged, washed, and dried to obtain a micron-sized, electrically polarized MOF composite (TM-ZrO2@NU66) powder composed of MOF and tourmaline.

[0077] Comparative Example 1

[0078] Dissolve 3 mmol of anhydrous zirconium chloride (ZrCl4) in 10 mL of deionized water, stir thoroughly, and label this solution A. Add 4.5 mmol of 2-aminoterephthalic acid to 10 mL of deionized water and dissolve thoroughly, label this solution B. Slowly add Solution B to Solution A and stir thoroughly. Then, add 10 mL of trifluoroacetic acid (TFA) as a crystal modifier to the mixture. Mix thoroughly and transfer the mixture to a polytetrafluoroethylene-lined reactor. Place the reactor in a forced-air drying oven and heat it from room temperature to 100°C at a rate of 1.0°C / min for 4 hours. After the reaction, cool naturally to room temperature. Subsequently, centrifuge, wash, and dry to obtain a MOF composite material (denoted as MOF(NU66)) powder.

[0079] Material performance testing

[0080] The traditional MOF (NU66) prepared in the comparative example and the micron-scale electrodeposited MOF composite material (TM-ZrO2@NU66) prepared in the present invention were characterized and analyzed. The following are the characterization results.

[0081] (a) SEM images of MOF (NU66) and TM-ZrO2@NU66.

[0082] The surface morphology of traditional MOF (NU66) and micron-scale electrodeposited MOF composite material (TM-ZrO2@NU66) was characterized by a Japanese Hitachi S-3400N low-magnification scanning electron microscope. Figure 1 shown. Figure 1 (Left) is the SEM image of traditional MOF (NU66), Figure 1(Right) is a SEM image of a micron-sized electrically polarized MOF composite (TM-ZrO2@NU66). Comparison shows that in the micron-sized electrically polarized MOF composite (TM-ZrO2@NU66), MOF (NU66) is uniformly loaded on the tourmaline surface.

[0083] (ii) EIS diagrams of MOF (NU66) and TM-ZrO2@NU66.

[0084] The resistance of traditional MOF (NU66) and micron-scale electrodeposited MOF composite material (TM-ZrO2@NU66) was tested using the P4000 electrochemical workstation of Princeton, USA. The results are as follows: Figure 2 As shown. Figure 2 It can be seen that the traditional MOF (NU66) has a relatively large resistance of 334.7Ω; while the resistance of the micron-scale electrically polarized MOF composite material (TM-ZrO2@NU66) is significantly reduced to only 88.8Ω. The resistance of MOF (NU66) is 3.77 times that of the product of the present invention (TM-ZrO2@NU66), proving that the electron transmission ability of the composite material of the present invention has been significantly enhanced.

[0085] (3) DRS spectra of MOF (NU66) and TM-ZrO2@NU66

[0086] The absorption properties of traditional MOF (NU66) and micron-scale electrodeposited MOF composite material (TM-ZrO2@NU66) were characterized using TU-1901 UV-visible spectrophotometer from Beijing Puxi General Instrument Co., Ltd. The DRS spectra obtained are shown in the figure below. Figure 3 As shown. Figure 3 It can be seen that the absorption edge of the composite material of the present invention is red-shifted compared with the traditional MOF (NU66). This is because the self-polarization electric field of tourmaline induces electronic polarization, which causes the absorption edge of the composite material to be red-shifted and the light absorption performance to be improved.

[0087] (IV) PL spectra of MOF (NU66) and TM-ZrO2@NU66

[0088] The photogenerated electron and hole separation ability of traditional MOF (NU66) and micron-scale electrodeposited MOF composite material (TM-ZrO2@NU66) was tested using a Hitachi F-4700 photoluminescence spectrometer. Figure 4 As shown. The higher the PL corresponding signal, the lower the recombination rate of photogenerated electrons and holes after the material is excited by light, and the higher the catalytic activity of the material. Figure 4It can be seen that the PL peak of TM-ZrO2@NU66 is significantly lower than that of MOF (NU66), which proves that the micron-scale electrically polarized MOF composite material (TM-ZrO2@NU66) has a stronger ability to separate photogenerated electrons and holes. This is mainly attributed to the spontaneous polarization electric field of tourmaline, which induces the photogenerated carriers to move in the opposite direction and effectively separates the photogenerated carriers.

[0089] (V) Photocatalytic degradation performance of MOF (NU66) and TM-ZrO2@NU66 for formaldehyde

[0090] The reaction was carried out in a well-sealed quartz reactor (350 ml). A PLS-SXE300 xenon lamp was used for photodegradation, and the formaldehyde concentration was monitored by a trace-level photospectroscopy gas analyzer (Gasera one pulse). The formaldehyde degradation efficiency was calculated. Figure 5 As can be seen, after 150 minutes of photocatalysis, the photocatalytic degradation rate of formaldehyde by NU66 was 59%. However, the photocatalytic degradation rate of formaldehyde by TM-ZrO2@NU66 was significantly better than that of the original NU66, reaching a final formaldehyde degradation efficiency of 90.02% after 150 minutes of photocatalysis, indicating that the TM-ZrO2@NU66 of the present invention has a good photocatalytic degradation effect.

[0091] (VI) Analysis of the photocatalytic degradation performance of TM-ZrO2NU66 prepared with different TM-ZrO2 doping amounts in gaseous formaldehyde

[0092] When the TM-ZrO2 doping amount increased from 10wt.% to 20wt.%, the prepared TM-ZrO2@NU66 was subjected to photocatalytic experiments. The results are shown in Figure 2. Figure 6 As shown. Figure 6 It can be seen that with the increase of TM-ZrO2 doping amount, the photocatalytic formaldehyde activity of the composite material gradually increases. Among them, when the doping amount is 20wt.%, the HCHO photodegradation efficiency is the highest, and after 2.5h of photocatalysis, the catalytic efficiency reaches 90.02%. However, when the doping amount is further increased to 25wt.%, the photocatalytic activity of the composite material decreases to 86%. This is because the addition of an appropriate amount of tourmaline (20wt.%) makes the tourmaline surface evenly covered with NU66 and exposes more catalytic sites, thereby effectively improving the catalytic activity. However, excessive doping will cause the tourmaline to accumulate, thereby reducing its optical and electrical properties, and thus reducing its catalytic ability to formaldehyde.

[0093] The examples provided herein are not intended to limit the embodiments of the present invention. Those skilled in the art will readily appreciate that variations or modifications may be made based on the above description. It is not necessary and impossible to enumerate all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing a micron-sized electrically polarized MOF composite material, comprising the following steps: (1) Preparation of tourmaline-homologous metal oxides; A certain amount of tourmaline powder is added to the ZrCl4 solution, stirred evenly, and the pH of the solution is adjusted to 6-11. The solution is stirred and ultrasonicated for 1-9 hours, then allowed to stand to obtain a colloidal precipitate. The colloidal precipitate is then filtered, washed with water until neutral, and air-dried. Finally, the solution is calcined at 200-600°C for 2-8 hours. After the reaction is completed, the solution is cooled to room temperature to obtain a tourmaline-homologous metal oxide composite powder, designated as TM-ZrO2. (2) Preparation of micron-scale electrodeposited MOF composites; Anhydrous zirconium chloride ZrCl4 is dissolved in water, and then 5-50 wt.% of tourmaline-homologous metal oxide composite powder TM-ZrO2 is added and stirred evenly, which is marked as solution A; 2-aminoterephthalic acid solution is then added to solution A and stirred evenly, and then trifluoroacetic acid is added to the mixture as a crystal form regulator. After mixing, the mixture is transferred to the lining of a reactor, and the reactor is placed in a forced air drying oven and reacted at 80-150°C for 4-24 hours. After the reaction, it is naturally cooled to room temperature, centrifuged, washed and dried to obtain a micron-sized electrically polarized MOF composite material of MOF and tourmaline.

2. The method for preparing a micron-sized electrically polarized MOF composite material according to claim 1, wherein: The ZrCl4 solution in step (1) is prepared by dissolving anhydrous ZrCl4 in water to obtain a ZrCl4 solution with a concentration of 0.1 to 0.5 mol / L.

3. The method for preparing the micron-sized electrically polarized MOF composite material according to claim 2, wherein: The amount of tourmaline added in step (1) is 5-200 wt.% of the mass of anhydrous ZrCl4, and the particle size of the tourmaline is 500-2000 mesh.

4. The method for preparing the micron-sized electrically polarized MOF composite material according to claim 1, wherein: In the step (1), NH3·H2O solution is used to adjust the pH value.

5. The method for preparing the micron-sized electrically polarized MOF composite material according to claim 1, wherein: In the step (1), the mixture is first stirred for 1 to 6 hours, then ultrasonicated for 0.5 to 3 hours, and then allowed to stand for 1 to 12 hours.

6. The method for preparing a micron-sized electrically polarized MOF composite material according to claim 1, wherein: In the step (2), the molar ratio of anhydrous zirconium chloride to 2-aminoterephthalic acid in solution A is 1: 1.1-1.

9.

7. The method for preparing a micron-sized electrically polarized MOF composite material according to claim 1, wherein: After the 2-aminoterephthalic acid solution in step (1) is added to solution A, the stirring time is 5 minutes to 2 hours.

8. The method for preparing a micron-sized electrically polarized MOF composite material according to claim 1, wherein: The volume ratio of trifluoroacetic acid added in step (2) to solution A is 6-15:

20.

9. The method for preparing the micron-sized electrically polarized MOF composite material according to claim 1, wherein: The specific reaction process of the blast drying oven in step (2) is: (a) Heating stage: heating to 80-150 °C at a rate of 0.5-5 °C / min; (b) Constant temperature stage: maintain at 80-150°C for 4-24 h.

10. The micron-sized electrically polarized MOF composite material obtained by the preparation method according to any one of claims 1 to 9, characterized in that: MOF grows firmly and evenly on the tourmaline surface, and the material after the micron-scale polarized MOF composite has good photoelectric properties.

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