Transition metal-doped three-dimensional hybrid zeolite imidazole framework photothermal materials and their preparation methods

Abstract

This invention discloses a method for preparing a transition metal-doped three-dimensional hybrid zeolite imidazole framework photothermal material. 2-Methylbenzimidazole is selected as the ligand linker, whose structure exhibits a high conjugation effect, which is beneficial for improving photothermal performance. Furthermore, transition metal ions are introduced into the three-dimensional hybrid zeolite imidazole framework to alter the framework's band structure, thereby broadening the material's light absorption range. The intrinsic d-d transitions of the transition metal ions can introduce additional photothermal conversion modules, further enhancing the material's photothermal performance. This method is simple and easy to operate, producing products with high purity, good crystallinity, and minimal agglomeration, which is beneficial for obtaining well-dispersed crystal particles. Test results show that transition metal ions were successfully doped into the HZIF-3 framework, and without altering the original crystal morphology, the photothermal performance was improved by 5-8°C compared to the undoped HZIF-3 powder material.

Description

Technical Field

[0001] This invention belongs to the field of MOF-based photothermal materials technology, specifically relating to a method for preparing a three-dimensional hybrid zeolite imidazole framework photothermal material doped with transition metals, and also relating to a three-dimensional hybrid zeolite imidazole framework photothermal material doped with transition metals. Background Technology

[0002] With population growth and the impact of climate change, global freshwater resources are gradually decreasing, while seawater reserves are abundant. Therefore, producing freshwater from seawater is one of the effective ways to alleviate water scarcity. In recent years, interfacial solar water evaporation systems have attracted much attention due to their low cost and high efficiency. Photothermal materials, as one of the most important components in interfacial solar water evaporation systems, are directly related to solar energy absorption and directly determine the evaporator's evaporation performance. Metal-organic frameworks (MOFs) are self-assembled from metal ions or metal clusters and organic ligands through coordination. Their structures are highly designable and controllable; by selecting different metal centers and organic ligands, the pore size, shape, and function can be adjusted, thereby optimizing light absorption and heat conversion efficiency. Among them, hybrid zeolite imidazole framework (HZIF) is a novel metal-organic framework. It introduces zeolite-like inorganic tetrahedral metal oxometalate TO4 into the crystal structure of zeolite-type metal imidazole framework, synthesizing a hybrid crystalline three-dimensional framework between ZIF and inorganic zeolite. It combines the advantages of high stability and structural designability of both, and the framework is endowed with unique physicochemical properties due to the introduction of high-valence metals. In addition, doping foreign metal ions into the Zn(II) nodes of HZIF can introduce new electronic energy levels into the band structure of HZIF to form interband trap sites, which is beneficial to broaden their light absorption range and reduce electron-hole recombination. It can also bring many other benefits. For example: (1) the band structure of MOF can be adjusted, thereby broadening their light absorption range; (2) the doped metal ions (e.g., Co) can be used to adjust the band structure of MOF, thereby broadening their light absorption range; 2+ and Cu 2+ (3) The intrinsic dd transition of the photothermal conversion module can be introduced; (4) A new metal-metal charge transfer (MMCT) mode is introduced to improve the separation efficiency of photogenerated electron-hole pairs; (5) Metal ion doping can also improve the stability of MOF.

[0003] Currently, the preparation cost of some photothermal materials is high and the process is complicated. In view of the above two points, this experiment adopts a one-step solvothermal method to synthesize a photothermal material with better performance. Summary of the Invention

[0004] The first objective of this invention is to provide a method for preparing a three-dimensional hybrid zeolite imidazole framework photothermal material doped with transition metals, which solves the problems of narrow light absorption range and poor photothermal conversion performance of photothermal materials.

[0005] A second objective of this invention is to provide a three-dimensional hybrid zeolite imidazole framework photothermal material doped with transition metals.

[0006] The first technical solution adopted in this invention is a method for preparing a three-dimensional hybrid zeolite imidazole framework photothermal material doped with transition metals, the specific operation steps of which are as follows:

[0007] Step 1: Weigh a certain amount of zinc citrate dihydrate, molybdic acid, and 2-methylbenzimidazole and dissolve them in N,N-dimethylformamide (DMF) solution, and stir thoroughly to obtain solution A.

[0008] Step 2: Weigh out a certain amount of metal acetates (copper acetate, cobalt acetate, nickel acetate, manganese acetate) and add them separately to solution A, mix and stir to obtain solutions containing different transition metal ions (Cu). 2+ Co 2+ Ni 2+ Mn 2+ Solution B.

[0009] Step 3: Transfer the solution B obtained in Step 2 to a stainless steel reactor with a polytetrafluoroethylene liner, place it in an oven with a programmed cooling function, adjust the temperature to 160℃, and set the time to 72h.

[0010] Step 4: After the reaction vessel has been slowly cooled to room temperature, it is taken out and the product is separated by vacuum filtration and washing. The product is in the form of blue-black lumps.

[0011] Step 5: Place the filtered product into a vacuum drying oven at 60°C and dry for 12 hours. After drying and grinding, obtain a blue-black powder.

[0012] The invention is further characterized in that,

[0013] In step 1, the molar ratio of zinc citrate dihydrate, molybdic acid, and 2-methylbenzimidazole is 1:11:6.

[0014] In step 1, the ratio of the total mass of zinc citrate dihydrate, molybdic acid, and 2-methylbenzimidazole to N,N-dimethylformamide is 0.65-0.7 g: 5-8 mL.

[0015] The stirring time in step 1 is 20-60 minutes.

[0016] In step 2, the molar ratio of metal acetate to zinc citrate dihydrate is 1:3.

[0017] In step 2, the metal acetate can be replaced by one of the following: nitrate, chloride, etc.

[0018] In step 3, the heating rate of the oven is 3-5℃ / min. If a programmable oven is unavailable, a regular oven can be used instead. When cooling down, simply turn off the oven power and allow it to naturally reach room temperature.

[0019] In step 3, the oven temperature is set to a range of 140-180℃, and the time range is 60-80h.

[0020] In step 4, a DMF solution is used for vacuum filtration and washing.

[0021] In step 4, ultrasonic treatment can be performed before filtration and washing to remove the precipitates adhering to the crystal surface.

[0022] In step 5, the temperature range of the vacuum drying oven is 40-80℃, and the time range is 8-20h.

[0023] The second technical solution adopted in this invention is a photothermal material prepared by a method for preparing a three-dimensional hybrid zeolite imidazole framework photothermal material doped with transition metals.

[0024] The beneficial effects of this invention are:

[0025] (1) The present invention adopts a simple one-step solvothermal method to mix the drugs and transfer them to a hydrothermal reactor. Under high temperature and high pressure reaction environment, a three-dimensional hybrid zeolite imidazole framework material doped with transition metal ions is synthesized. The framework has multiple metal active sites, and the high conjugation effect of the ligands makes the material have excellent photothermal conversion performance.

[0026] (2) The photothermal material prepared in this invention exhibits excellent photothermal conversion performance under xenon lamp irradiation. The photothermal performance was tested by adjusting the xenon lamp source to a solar intensity, in which Cu, a transition metal doped, was incorporated. 2+ The highest average surface temperature of the sample reached 90℃ after 10 minutes of light exposure.

[0027] (3) This invention involves doping transition metal ions (Cu) during the synthesis process. 2+ Co 2+ Ni 2+ Mn 2+ Therefore, the Zn in the HZIF-3 framework 2+ By replacing sites to control the crystal structure, the photothermal properties of the material can be improved. This method can also be explored in conjunction with other methods related to Zn. 2+ Doping with isomorphic transition metal ions is an extended synthesis strategy. Attached Figure Description

[0028] Figure 1 This is a flowchart of the preparation method of the transition metal ion-doped hybrid zeolite imidazole framework photothermal material of the present invention;

[0029] Figure 2 The transition metal Cu in this invention 2+ XRD diffraction pattern of doped hybrid zeolite imidazole framework photothermal material;

[0030] Figure 3 The present invention relates to the transition metal Cu. 2+ SEM image of a doped hybrid zeolite imidazole framework photothermal material.

[0031] Figure 4 The present invention relates to the transition metal Cu. 2+ Infrared image of the surface of a doped hybrid zeolite imidazole framework photothermal material irradiated with one solar intensity for 800 s.

[0032] Figure 5 The present invention is based on the transition metal Cu. 2+ Temperature curve of doped hybrid zeolite imidazole framework photothermal material irradiated with one solar intensity for 800 s.

[0033] Figure 6 The present invention relates to the transition metal Cu. 2+ Cyclic curve of doped hybrid zeolite imidazole framework photothermal material after 10 irradiations under one solar intensity.

[0034] Figure 7 The present invention relates to the transition metal Cu. 2+ Absorption diagram of doped hybrid zeolite imidazole framework photothermal material in the ultraviolet-visible-near-infrared region. Detailed Implementation

[0035] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0036] The purpose of this invention is to introduce transition metal ions (Cu) into the synthesis of HZIF-3. 2+ Co 2+ Ni 2+ Mn 2+ A three-dimensional hybrid zeolite imidazole framework photothermal material doped with transition metal ions was obtained. Compared with the traditional solid-state synthesis method, the solvothermal method can eliminate the calcination and grinding steps, reduce the possibility of powder contamination, and improve the purity and crystal integrity of the product. This method allows for the adjustment of the reaction atmosphere, enabling each ion to be uniformly doped within the crystal framework. Furthermore, the intrinsic dd transitions of the doped metal ions can introduce additional photothermal conversion modules, promoting the electron transfer rate and further improving the photothermal performance of the material. Finally, the three-dimensional hybrid zeolite imidazole framework photothermal powder material doped with transition metal ions was obtained through processes such as filtration, washing, and drying.

[0037] The present invention will be further described below with reference to specific embodiments.

[0038] Example 1

[0039] The preparation method of the transition metal ion-doped three-dimensional hybrid zeolite imidazole framework photothermal powder material of the present invention is as follows: Figure 1 As shown, the specific operation steps are as follows:

[0040] Step 1: Weigh 0.122 g (0.2 mmol) of zinc citrate dihydrate, 0.38 g (2.117 mmol) of molybdic acid and 0.158 g (1.196 mmol) of 2-methylbenzimidazole and dissolve them in 5 mL of N,N-dimethylformamide (DMF) solution. Stir thoroughly to obtain solution A.

[0041] Step 2: Weigh 0.013 g (0.067 mmol) of copper acetate and add it to solution A. Stir thoroughly to obtain a solution containing the transition metal Cu. 2+ Solution B.

[0042] Step 3: Transfer solution B from step 2 to a stainless steel reactor lined with polytetrafluoroethylene, place it in an oven with programmed cooling function, set the temperature to 160℃, and the time to 72h.

[0043] Step 4: After the reaction vessel has been slowly cooled to room temperature, it is removed and the product is separated by washing with DMF solution through vacuum filtration. The product is in the form of blue-black lumps.

[0044] Step 5: Place the filtered product into a vacuum drying oven at 60°C and dry for 12 hours. After drying and grinding, obtain a blue-black powder.

[0045] Example 2

[0046] Step 1: Weigh 0.122 g (0.2 mmol) of zinc citrate dihydrate, 0.38 g (2.117 mmol) of molybdic acid and 0.158 g (1.196 mmol) of 2-methylbenzimidazole and dissolve them in 5 mL of N,N-dimethylformamide (DMF) solution. Stir thoroughly to obtain solution A.

[0047] Step 2: Weigh 0.017 g (0.067 mmol) of cobalt acetate and add it to solution A, stirring thoroughly to obtain a solution containing the transition metal Co. 2+ Solution B.

[0048] Step 3: Transfer solution B from step 2 to a stainless steel reactor lined with polytetrafluoroethylene, place it in an oven with programmed cooling function, set the temperature to 160℃, and the time to 72h.

[0049] Step 4: After the reaction vessel has been slowly cooled to room temperature, it is removed and the product is separated by washing with DMF solution through vacuum filtration. The product is in the form of blue-black lumps.

[0050] Step 5: Place the filtered product into a vacuum drying oven at 50°C and dry for 16 hours. After drying and grinding, obtain a blue-black powder.

[0051] Example 3

[0052] Step 1: Weigh 0.122 g (0.2 mmol) of zinc citrate dihydrate, 0.38 g (2.117 mmol) of molybdic acid and 0.158 g (1.196 mmol) of 2-methylbenzimidazole and dissolve them in 5 mL of N,N-dimethylformamide (DMF) solution. Stir thoroughly to obtain solution A.

[0053] Step 2: Weigh 0.017 g (0.067 mmol) of nickel acetate and add it to solution A, stirring thoroughly to obtain a solution containing the transition metal Ni. 2+ Solution B.

[0054] Step 3: Transfer solution B from step 2 to a stainless steel reactor lined with polytetrafluoroethylene, place it in an oven with programmed cooling function, set the temperature to 160℃, and the time to 72h.

[0055] Step 4: After the reaction vessel has been slowly cooled to room temperature, it is removed and the product is separated by washing with DMF solution through vacuum filtration. The product is in the form of blue-black lumps.

[0056] Step 5: Place the filtered product into a vacuum drying oven at 60°C and dry for 12 hours. After drying and grinding, obtain a blue-black powder.

[0057] Example 4

[0058] Step 1: Weigh 0.122 g (0.2 mmol) of zinc citrate dihydrate, 0.38 g (2.117 mmol) of molybdic acid and 0.158 g (1.196 mmol) of 2-methylbenzimidazole and dissolve them in 5 mL of N,N-dimethylformamide (DMF) solution. Stir thoroughly to obtain solution A.

[0059] Step 2: Weigh 0.016 g (0.067 mmol) of manganese acetate and add it to solution A, stirring thoroughly to obtain a solution containing the transition metal Mn. 2+ Solution B.

[0060] Step 3: Transfer solution B from step 2 to a stainless steel reactor lined with polytetrafluoroethylene, place it in an oven with programmed cooling function, set the temperature to 160℃, and the time to 72h.

[0061] Step 5: After the reaction vessel has been slowly cooled to room temperature, it is taken out and the product is separated by washing with DMF solution through vacuum filtration. The product is in the form of blue-black lumps.

[0062] Step 6: Place the filtered product into a vacuum drying oven at 60°C and dry for 12 hours. After drying and grinding, obtain a blue-black powder.

[0063] Example 5

[0064] Step 1: Weigh 0.122 g (0.2 mmol) of zinc citrate dihydrate, 0.38 g (2.117 mmol) of molybdic acid and 0.158 g (1.196 mmol) of 2-methylbenzimidazole and dissolve them in 7 mL of N,N-dimethylformamide (DMF) solution. Stir thoroughly to obtain solution A.

[0065] Step 2: Weigh 0.013 g (0.067 mmol) of copper acetate and add it to solution A. Stir thoroughly to obtain a solution containing the transition metal Cu. 2+ Solution B.

[0066] Step 3: Transfer solution B from step 2 to a stainless steel reactor lined with polytetrafluoroethylene, place it in an oven with programmed cooling function, set the temperature to 170℃, and the time to 76h.

[0067] Step 4: After the reaction vessel has been slowly cooled to room temperature, it is removed and the product is separated by washing with DMF solution through vacuum filtration. The product is in the form of blue-black lumps.

[0068] Step 5: Place the filtered product into a vacuum drying oven at 50°C and dry for 16 hours. After drying and grinding, obtain a blue-black powder.

[0069] Detailed description of the attached diagram:

[0070] like Figure 2 As shown, this is the transition metal (Cu) prepared according to the present invention. 2+ The XRD diffraction pattern of the ion-doped HZIF-3 framework photothermal material shows good comparison with the XRD curve of the undoped HZIF-3 crystal, proving the successful synthesis of the transition metal ion-doped HZIF-3 framework photothermal material.

[0071] like Figure 3 As shown, Cu in this invention 2+ The SEM image of the doped HZIF-3 crystal shows that the doping of transition metal ions did not change the original morphology of the crystal and that each element was uniformly loaded on the crystal surface.

[0072] like Figure 4 As shown, Cu in this invention 2+Infrared images of the surface of the HZIF-3 photothermal powder material after 10 minutes of xenon lamp irradiation at an intensity of one solar day. The sample surface temperature rose to 60°C after 50 seconds of irradiation, exhibiting the fastest heating rate. The heating rate slowed down between 100 and 300 seconds, reaching a maximum temperature of 90°C at 220 seconds. After the xenon lamp was turned off, the temperature rapidly decreased to 70°C within 20 seconds. Subsequently, the sample cooled slowly, reaching room temperature at 800 seconds. This demonstrates that the sample possesses excellent photothermal conversion capabilities, able to reach and maintain a stable maximum temperature within a short time, and to cool to room temperature quickly after the lamp is turned off.

[0073] like Figure 5 As shown, Cu in this invention 2+ Temperature change curves of the doped HZIF-3 photothermal powder material under xenon lamp irradiation for 10 minutes at an intensity of one solar sun. At the beginning of irradiation, the temperature rises rapidly from 25℃ to 65℃ within 0-60 seconds. Between 60-150 seconds, the temperature increase slows slightly, rising from 65℃ to 85℃. After 200 seconds, the temperature rises very slowly, reaching 90℃ at 380 seconds, after which the temperature tends to stabilize.

[0074] like Figure 6 As shown, Cu in this invention 2+ Cyclic photothermal performance test curves of the doped HZIF-3 photothermal powder material. Under one solar intensity, the photothermal material was subjected to 10 light irradiation tests. As time increased, the photothermal performance of the material tended to stabilize, and the temperature could still rise to 90℃.

[0075] like Figure 7 As shown, Cu in this invention 2+ Absorption patterns of doped HZIF-3 photothermal powder materials in the ultraviolet-visible-near-infrared regions. Doped with transition metal Cu. 2+ The subsequent samples showed improved absorption in the near-infrared range of 1000-2500 nm, indicating that doping transition metal ions into the HZIF-3 framework is beneficial to improving the light absorption of the material, thereby enhancing the photothermal conversion capability of the powder material.

[0076] The synthesis principle of the key steps in this invention:

[0077] (I) A simple one-step solvothermal method was used to synthesize a three-dimensional hybrid zeolite imidazole framework doped with transition metal ions, introducing transition metal ions (Cu) during the solvothermal process. 2+ Co 2+ Ni 2+ Mn 2+By altering the band structure of the framework, the light absorption range of the material can be broadened. The intrinsic dd transition of transition metal ions can introduce additional photothermal conversion modules, further improving the photothermal performance of the material.

[0078] (ii) Under solvothermal conditions, the reaction environment atmosphere is easy to adjust, which facilitates the synthesis of low-valence, intermediate-valence and special-valence compounds, and enables uniform doping of metal ions. The synthesis process consumes less energy and reduces agglomeration.

Claims

1. A method for preparing a transition metal-doped three-dimensional hybrid zeolite imidazole framework photothermal material, characterized in that, The specific operating steps are as follows: Step 1: Weigh zinc citrate dihydrate, molybdic acid, and 2-methylbenzimidazole, and dissolve the raw materials in N,N-dimethylformamide solution, stirring thoroughly to obtain solution A; stirring time is 20 min - 60 min. In step 1, the molar ratio of zinc citrate dihydrate, molybdic acid, and 2-methylbenzimidazole is 1:11:6; The ratio of the total mass of zinc citrate dihydrate, molybdic acid, and 2-methylbenzimidazole to N,N-dimethylformamide in step 1 is 0.65-0.7 g: 5-8 mL; Step 2: Add acetate to solution A separately, mix and stir to obtain solution B containing transition metal ions; The molar ratio of zinc citrate dihydrate to acetate is 3:1; The acetate mentioned in step 2 is any one of copper acetate, cobalt acetate, nickel acetate, and manganese acetate; Step 3: Transfer solution B from step 2 to a stainless steel reactor with a polytetrafluoroethylene liner, place it in an oven with a programmed cooling function, adjust the temperature to 160℃~170℃, and maintain it for 72 h~76 h. Step 4: After the reaction vessel has been slowly cooled to room temperature, it is removed and the product is separated by filtration and washing. Step 5: Place the product obtained by vacuum filtration into a vacuum drying oven at 50℃~60℃ and dry for 12h~16h. After drying and grinding, obtain the photothermal material.

2. The method for preparing the transition metal-doped three-dimensional hybrid zeolite imidazole framework photothermal material according to claim 1, characterized in that, The heating rate of the oven is 3-5℃ / min.

3. The method for preparing the transition metal-doped three-dimensional hybrid zeolite imidazole framework photothermal material according to claim 1, characterized in that, The solution used in the filtration and washing operation described in step 4 is a DMF solution.

4. A three-dimensional hybrid zeolite imidazole framework photothermal material doped with transition metals, characterized in that, The material was prepared using the method described in any one of claims 1-3 for the preparation of a three-dimensional hybrid zeolite imidazole framework photothermal material doped with transition metals.

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