Metal organic framework nano-material with adjustable and controllable photo-thermal performance and preparation method of metal organic framework nano-material

Abstract

The invention relates to the technical field of energy conversion materials, and discloses a metal organic framework nano material with adjustable photo-thermal performance and a preparation method of the metal organic framework nano material. According to the method, two ligands with different functional groups, namely 2-aminoterephthalic acid and 2-fluoroterephthalic acid, are used for regulating and controlling the near-infrared light absorption capacity of the metal organic framework, so that the photothermal conversion temperature is accurately controlled by changing the proportion of the ligands. Compared with the traditional mode of improving the photo-thermal performance by depending on changing the optical power density, the metal organic framework nano material provided by the invention has remarkable advantages in the aspects of preparation process, structure controllability and photo-thermal conversion performance regulation and control.

Description

Technical Field

[0001] The present invention relates to the technical field of energy conversion materials, and in particular to a metal organic framework nanomaterial with adjustable photothermal properties and a preparation method thereof. Background Art

[0002] As a renewable clean energy, the efficient storage and utilization of light energy is of great significance for promoting sustainable development strategies. Photothermal conversion materials are the key medium for realizing the conversion of light energy into thermal energy. Such materials convert light energy into thermal energy through a variety of photothermal conversion mechanisms, and their light absorption capacity and photothermal conversion efficiency can be adjusted by optimizing the micro- and macro-structures of the materials to achieve efficient utilization of light energy.

[0003] At present, photothermal materials are mainly divided into four categories: precious metal nanomaterials (gold nanorods and gold nanowires), transition metal materials (MoS2 and WS2), carbon-based nanomaterials (carbon nanotubes and graphene oxide), and organic conjugated materials (cyanine and porphyrin). Although these photothermal materials have made certain progress in research, they still have many problems such as high cost, non-degradability, and biological toxicity. For example, precious metal nanomaterials are relatively expensive and non-degradable; transition metal materials may have poor photostability; carbon-based nanomaterials may be biologically toxic; organic conjugated materials usually involve the synthesis of toxic chemical reagents, and their structures are unstable and prone to photobleaching.

[0004] Therefore, developing an environmentally friendly, stable, and efficient photothermal conversion material has become an urgent need to achieve a low-carbon economy and sustainable development. Summary of the invention

[0005] The purpose of the present invention is to solve the problem of uncontrollable structure of existing organic photothermal materials, and to provide a metal organic framework nanomaterial with adjustable photothermal performance and a preparation method thereof. The present invention uses ligands 2-aminoterephthalic acid and 2-fluoroterephthalic acid with different functional groups to adjust the absorption capacity of the metal organic framework to near-infrared light, thereby achieving the regulation of the photothermal conversion temperature by precisely controlling the ligand ratio.

[0006] The specific technical solutions of the present invention include: On the one hand, the present invention provides a metal-organic framework nanomaterial with adjustable photothermal properties. The material is formed by complexing zirconium ions with ligands, and the ligands are 2-aminoterephthalic acid and / or 2-fluoroterephthalic acid. The material achieves control of the photothermal properties by adjusting the ratio of amino groups and fluorine groups in the material.

[0007] The present invention introduces ligands 2-aminoterephthalic acid and 2-fluoroterephthalic acid with different functional groups into a metal organic framework, and by adjusting the ratio of the two, the material's absorption of near-infrared light and photothermal conversion efficiency can be precisely adjusted, thereby achieving the controllability of the photothermal conversion temperature.

[0008] On the other hand, the present invention also provides a method for preparing a metal organic framework nanomaterial with adjustable photothermal properties, comprising the following steps: The zirconium salt and the ligand are dissolved in a solvent, ultrasonicated, allowed to stand, and the solid is separated to obtain a metal organic framework nanomaterial; wherein: The ligand is obtained by mixing 2-aminoterephthalic acid and 2-fluoroterephthalic acid in a molar ratio of 0-10:10-0.

[0009] In the above preparation method, the molar ratio of zirconium salt to ligand is preferably 1:(1-1.2).

[0010] As a preferred embodiment of the above preparation method, the solvent is a mixed solvent of dimethylformamide, acetic acid and water.

[0011] As a preferred embodiment of the above preparation method, the preferred solvent is dimethylformamide, acetic acid and water in a volume ratio of 15:6:1.

[0012] Dimethylformamide can effectively dissolve the ligand, acetic acid can adjust the acidity and alkalinity of the solvent, and promote the growth of metal organic framework nanomaterials. The addition of an appropriate amount of water helps the precipitation of crystals.

[0013] As a preferred embodiment of the above preparation method, the zirconium salt is zirconium chloride and / or zirconium nitrate.

[0014] As a preferred embodiment of the above preparation method, the ultrasonic treatment time is 4 to 10 minutes.

[0015] As a preferred embodiment of the above preparation method, the standing temperature is 120-160° C. and the standing time is 20-30 hours.

[0016] The standing step is crucial for the crystallization of the metal organic framework. Appropriate temperature and time can ensure the crystallinity and structural stability of the material. If the temperature is too high or too low, it will affect the nucleation efficiency of the metal organic framework, thereby affecting the performance of the material. Therefore, in the present invention, the crystallization of the metal organic framework nanomaterial needs to be stood for 20 to 30 hours in the temperature range of 120 to 160 ° C. The temperature deviates from this range and may cause incomplete or uneven crystal nucleation, thereby affecting the quality and performance of the material.

[0017] As a preferred embodiment of the above preparation method, the method for separating the solid is centrifugation and washing with ethanol to remove impurities to ensure that high-purity metal organic framework nanomaterials are obtained.

[0018] Compared with the prior art, the present invention has the following technical effects: 1. By precisely controlling the ratio of the two ligands, 2-aminoterephthalic acid and 2-fluoroterephthalic acid, the absorption of near-infrared light by the metal-organic framework can be effectively regulated, and the photothermal conversion temperature can be precisely adjusted to achieve the controllability of the photothermal performance.

[0019] 2. The preparation method is simple to operate, low-cost, does not require complicated chemical synthesis steps, conforms to the principle of environmentally friendly preparation, and provides a new efficient and economical way to regulate the photothermal conversion efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The light-to-heat conversion test results of the metal organic framework materials prepared in Examples 1 to 5 of the present invention; Figure 2 The cyclic stability test results of the metal organic framework materials prepared in Examples 1 to 5 of the present invention; Figure 3 These are the test results of the temperature difference of the metal organic framework materials prepared in Examples 1 to 5 of the present invention as a function of power density. DETAILED DESCRIPTION

[0021] The present invention will be further described below in conjunction with embodiments. For those of ordinary skill in the art, the present invention can be smoothly implemented on the basis of fully understanding the following description. In addition, the following embodiments are only a part of the present invention and do not cover all embodiments. Therefore, any simple modification, change or equivalent substitution made on the basis of the technical scheme of the present invention should all fall into the protection scope of the present invention.

[0022] Example 1 This embodiment provides a method for preparing a metal organic framework material. The specific preparation steps are as follows: First, prepare the ligands 2-aminoterephthalic acid (NH2-BDC) and 2-fluoroterephthalic acid (F-BDC) in a molar ratio of 10:0. Specifically, weigh 0.15 g of ZrCl4 and 0.176 g of NH2-BDC.

[0023] Then, the solid substance was dissolved in a mixed solution consisting of 15 mL of dimethylformamide (DMF), 6 mL of acetic acid, and 1 mL of deionized water. After the substance was fully dissolved, the solution was placed in an ultrasonic bath and ultrasonicated for 5 minutes.

[0024] After the ultrasonic treatment, the solution was placed at 150°C for 24 hours. After the standing period, the solid was separated by centrifugation at 8000 rpm for 3 minutes, the supernatant was removed, and the precipitate was washed with 15 mL of ethanol. This step was repeated three times to ensure that the precipitate was fully washed.

[0025] Finally, the obtained precipitate was vacuum dried at 60° C. for 12 hours to obtain metal organic framework nanoparticles with a ligand molar ratio of NH 2 -BDC:F-BDC=10:0.

[0026] Example 2 The difference between this embodiment and embodiment 1 is that the ligands 2-aminoterephthalic acid (NH2-BDC) and 2-fluoroterephthalic acid (F-BDC) are prepared in a molar ratio of 7:3, specifically, 0.15 g of ZrCl4, 0.123 g of NH2-BDC and 0.0528 g of F-BDC are weighed. The other steps are the same as those in embodiment 1.

[0027] Example 3 The difference between this embodiment and embodiment 1 is that the ligands 2-aminoterephthalic acid (NH2-BDC) and 2-fluoroterephthalic acid (F-BDC) are prepared in a molar ratio of 5:5, specifically, 0.15 g of ZrCl4, 0.088 g of NH2-BDC, and 0.087 g of F-BDC are weighed. The other steps are the same as those in embodiment 1.

[0028] Example 4 The difference between this embodiment and embodiment 1 is that the ligands 2-aminoterephthalic acid (NH2-BDC) and 2-fluoroterephthalic acid (F-BDC) are prepared in a molar ratio of 3:7, specifically, 0.15 g of ZrCl4, 0.0528 g of NH2-BDC, and 0.123 g of F-BDC are weighed. The other steps are the same as those in embodiment 1.

[0029] Example 5 The difference between this embodiment and embodiment 1 is that the ligands 2-aminoterephthalic acid (NH2-BDC) and 2-fluoroterephthalic acid (F-BDC) are prepared in a molar ratio of 0:10, specifically, 0.15 g of ZrCl4 and 0.176 g of F-BDC are weighed. The other steps are the same as those in embodiment 1.

[0030] Comparative Example 1 The only difference between this comparative example and Example 1 is that the weighed substances are dissolved together in 15 mL of DMF. The other steps are the same as those in Example 1.

[0031] In this comparative example, it was found that no precipitation could be obtained after standing at 150° C. for 24 hours and then centrifuging at 8000 rpm for 3 minutes.

[0032] Comparative Example 2 The only difference between this comparative example and Example 1 is that the weighed substances are dissolved in a mixed solution of 15 mL DMF and 7 mL acetic acid. The other steps are the same as those in Example 1.

[0033] This comparative example found that after standing at 150° C. for 24 hours and then centrifuging at 8000 rpm for 3 minutes, less precipitate was obtained. After three washes, very little precipitate remained.

[0034] Performance Testing (1) The metal organic framework materials prepared in Examples 1 to 5 were tested for photothermal conversion. The results are shown in Figure 1 , wherein: Example 1 represents Example 1, Example 2 represents Example 2, ..., Example 5 represents Example 5. The test method and test setting conditions are as follows: 10 mg of the metal organic framework material is placed in a glass container, the metal organic framework is irradiated with an 808 nm infrared exciter at a height of 20 cm, and the surface temperature change of the metal organic framework is recorded with an infrared thermal imager.

[0035] from Figure 1 It can be seen that the temperature of the metal organic framework with only amino groups is the highest. From the characterization results of Examples 1 to 5, it can be seen that with the decrease of the amino group content and the increase of the fluorine group content, the temperature of the metal organic framework shows a downward trend.

[0036] (2) The metal organic framework materials prepared in Examples 1 to 5 were subjected to a cyclic stability test. The results are shown in Figure 2 , wherein: Example 1 represents Example 1, Example 2 represents Example 2, ..., Example 5 represents Example 5. The test method and test setting conditions are as follows: 10 mg of the metal organic framework material is placed in a glass container, the metal organic framework is irradiated with an 808 nm infrared exciter at a height of 20 cm, and the surface temperature change of the metal organic framework is recorded with an infrared thermal imager.

[0037] from Figure 2 It can be seen that the temperatures reached by the materials obtained in Examples 1 to 5 after three cycles of photothermal conversion are almost the same, and the materials obtained in Examples 1 to 5 have excellent cycle stability.

[0038] (3) The metal organic framework materials prepared in Examples 1 to 5 were tested for temperature difference as a function of power density. The temperature difference refers to the difference between the highest temperature and the lowest temperature of the material after multiple tests of the photothermal conversion of the material at the same power. The photothermal conversion test method and setting conditions refer to step (1). The test results of temperature difference as a function of power density are shown in Figure 3 , where: Example 1 represents Example 1, Example 2 represents Example 2,..., Example 5 represents Example 5.

[0039] Depend on Figure 3 From the characterization results of Examples 1 to 5, it can be seen that with the increase of the irradiation power density, the higher the amino content, the greater the temperature difference; and the higher the fluorine content, the smaller the temperature difference.

[0040] The raw materials and equipment used in the present invention, unless otherwise specified, are all commonly used raw materials and equipment in the art; the methods used in the present invention, unless otherwise specified, are all conventional methods in the art.

[0041] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent transformation made to the above embodiment based on the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A metal-organic framework nanomaterial with adjustable photothermal properties, characterized in that: The material is formed by complexing zirconium ions with ligands, wherein the ligands are 2-aminoterephthalic acid and / or 2-fluoroterephthalic acid; The photothermal performance of the material is adjusted by regulating the content ratio of the amino group and the fluorine group in the material.

2. A method for preparing a metal organic framework nanomaterial with adjustable photothermal properties, comprising the following preparation steps: The zirconium salt and the ligand are dissolved in a solvent, ultrasonicated, allowed to stand for reaction, and the solid is separated to obtain a metal organic framework nanomaterial; wherein: The ligand is obtained by mixing 2-aminoterephthalic acid and 2-fluoroterephthalic acid in a molar ratio of 0-10:10-0.

3. The preparation method according to claim 2, characterized in that: The molar ratio of the zirconium salt to the ligand is 1:1-1.

2.

4. The preparation method according to claim 2, characterized in that: The solvent is a mixed solvent of dimethylformamide, acetic acid and water.

5. The preparation method according to claim 4, characterized in that: The volume ratio of dimethylformamide, acetic acid and water is 15:6:

1.

6. The preparation method according to claim 2, characterized in that: The zirconium salt is zirconium chloride and / or zirconium nitrate.

7. The preparation method according to claim 2, characterized in that: The ultrasonic time is 4 to 10 minutes.

8. The preparation method according to claim 2, characterized in that: The standing temperature is 120-160° C., and the standing time is 20-30 hours.

9. The preparation method according to claim 2, characterized in that: The method for separating the solids is centrifugation.

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