Two-dimensional conductive metal organic framework material and preparation method and application thereof
By preparing Mg3(HITP)2 two-dimensional conductive metal-organic framework material, the high temperature and high energy consumption problem of existing ammonia sensors has been solved, realizing ammonia sensing with high sensitivity and high selectivity at room temperature. It is suitable for portable devices and has broad application prospects.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SOUTHEAST UNIV
- Filing Date
- 2026-02-06
- Publication Date
- 2026-05-12
AI Technical Summary
Existing ammonia sensors suffer from problems such as high operating temperature, high power consumption, poor selectivity, and structural rigidity. Moreover, most metal-organic framework materials are insulators with low conductivity, which limits their application in electrical sensing, resulting in poor sensitivity, stability, and selectivity.
A two-dimensional conductive metal-organic framework material with the chemical formula Mg3(HITP)2 was prepared by introducing metal defects and nitrogen vacancies through controlled synthesis conditions. The material with a two-dimensional layered structure was used as the sensing layer of a room temperature ammonia gas sensor. Ammonia water or sodium acetate was used as a catalyst and coated on the surface of the gold interdigitated electrode.
It achieves high sensitivity, high selectivity and fast response to ammonia at room temperature, and is suitable for flexible portable gas sensing devices. The response rate is over 20%, the response recovery time is in the second range, and the detection limit is as low as tens of ppb. The sensor device can simplify the structure and reduce power consumption.
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Figure CN122011410A_ABST
Abstract
Description
Technical Field
[0001] This invention pertains to framework materials, their preparation methods and applications, specifically a two-dimensional conductive metal-organic framework material, its preparation method and application. Background Technology
[0002] Ammonia (NH3) is widely used in industry and agriculture, but it is toxic, irritating, and corrosive. Long-term exposure to low concentrations of ammonia can harm human health. Currently, traditional ammonia sensors are mostly based on metal oxide semiconductors or solid electrolytes, which suffer from high operating temperatures, high power consumption, poor selectivity, and structural rigidity, making them unsuitable for flexible, portable electronic devices (ACS Cent. Sci. 2022, 8, 1196.; Chin. Chem. Lett. 2021, 32, 1994). Most metal-organic frameworks (MOFs) are insulators with low conductivity, limiting their application in electrical sensing. Existing ammonia sensors require further improvement in defect control and performance optimization, exhibiting unsatisfactory sensitivity, stability, and selectivity. Summary of the Invention
[0003] Purpose of the invention: In order to overcome the shortcomings of the prior art, the purpose of this invention is to provide a two-dimensional conductive metal-organic framework material with low power consumption, high selectivity, high sensitivity and fast response. Another purpose of this invention is to provide a method for preparing a flexible and portable two-dimensional conductive metal-organic framework material. Yet another purpose of this invention is to provide an application of the two-dimensional conductive metal-organic framework material in the sensing layer of a room temperature ammonia gas sensor.
[0004] Technical solution: The present invention discloses a two-dimensional conductive metal-organic framework material with the chemical formula Mg3(HITP)2, which has a two-dimensional layered stacked structure and contains magnesium defects and nitrogen vacancies.
[0005] The present invention discloses a method for preparing a two-dimensional conductive metal-organic framework material, which involves stirring and mixing a hexaaminotriphenylene hydrochloride solution (HATP·6HCl), a magnesium acetate solution, and a catalyst until homogeneous, stirring and reacting, centrifuging and separating the solid precipitate, washing and drying it to obtain the two-dimensional conductive metal-organic framework material.
[0006] Furthermore, the concentration of the hexaaminotrimethylene hydrochloride solution is 9–15 mmol / L, and the solvent is deionized water. A concentration of hexaaminotrimethylene hydrochloride solution below 9 mmol / L significantly reduces the yield; a concentration above 15 mmol / L drastically reduces the material's sensing performance.
[0007] Furthermore, the concentration of the magnesium acetate solution is 25–40 mmol / L, and the solvent is deionized water. A concentration of magnesium acetate solution below 25 mmol / L will slightly reduce the yield; a concentration of magnesium acetate solution above 40 mmol / L will slightly reduce the sensing performance of the material.
[0008] Furthermore, the catalyst is an aqueous ammonia solution or a sodium acetate solution, and the solvent is deionized water. The catalyst helps to delay the ineffective binding of ligands to metal precursors, regulates the ordered self-assembly process of metal ions and organic ligands, exposes more active sites in the MOF, and improves the sensing performance of the material.
[0009] Furthermore, the concentration of the ammonia solution is 3-6 mol / L, and the concentration of the sodium acetate solution is 2-4 mol / L.
[0010] Furthermore, the volume ratio of hexaaminotriphenylene hydrochloride solution, magnesium acetate solution, and catalyst is 10:10:3~5.
[0011] Furthermore, the temperature of the stirring reaction is 65~85℃, and the time is 2~4 hours.
[0012] Further, the magnesium acetate solution was mixed with the catalyst and stirred until homogeneous. Then, an equal volume of hexaaminotriphenylene hydrochloride solution was quickly added and stirred at room temperature.
[0013] This invention provides an application of a two-dimensional conductive metal-organic framework material in the sensing layer of a room temperature ammonia gas sensor.
[0014] Furthermore, the sensing layer is coated on the surface of the gold interdigitated electrode, and the room temperature ammonia sensor has a response value of over 39% for ammonia gas concentrations above 50 ppm.
[0015] Preparation principle: Ammonia or sodium acetate is used as a synthesis catalyst. By controlling the synthesis conditions, abundant metal defects and nitrogen vacancies are introduced into the material, thereby significantly improving its gas sensing performance. The more metal defect sites there are, the stronger the adsorption capacity for ammonia molecules.
[0016] Beneficial effects: Compared with the prior art, the present invention has the following significant features:
[0017] 1. The obtained two-dimensional conductive metal-organic framework material has a two-dimensional conjugated molecular structure, high conductivity, abundant defect structure and excellent gas adsorption capacity. It exhibits high sensitivity, high selectivity, fast response and good stability to ammonia at room temperature. It is suitable for flexible and portable gas sensing devices and has broad application prospects in environmental monitoring, medical health, Internet of Things and other fields.
[0018] 2. The obtained ammonia sensor can realize room temperature, wireless, real-time ammonia monitoring. The response rate to 50 ppm NH3 is over 20%, the response and recovery time is in the second range, the detection limit is as low as tens of ppb, and it maintains stable sensing performance for 35 days. It has high selectivity to a variety of interfering gases. The sensor can quickly detect ammonia concentration at room temperature without heating, which can simplify the device structure and reduce device power consumption. Attached Figure Description
[0019] Figure 1 This is a TEM image of Mg3(HITP)2 from the present invention;
[0020] Figure 2 This is a SEM image of Mg3(HITP)2 from the present invention;
[0021] Figure 3 This is the XRD pattern of Mg3(HITP)2 of the present invention;
[0022] Figure 4 This is the Raman spectrum of Mg3(HITP)2 of the present invention;
[0023] Figure 5 This is the EPR diagram of Mg3(HITP)2 of the present invention.
[0024] Figure 6 This invention describes the room temperature gas sensing performance of Mg3(HITP)2, wherein (a) is the dynamic response-recovery curve of NH3 at different concentrations (1-200 ppm) at room temperature, (b) is the response-recovery time curve of NH3 at 50 ppm at room temperature, (c) is the graph showing the change in response value of NH3 at different concentrations (1-200 ppm) at room temperature, (d) is the comparison graph of response values of different gases at 50 ppm at room temperature, and (e) is the fitting curve of response value of NH3 at 11200 ppm. Detailed Implementation
[0025] In the following examples, experimental methods without specific conditions were generally performed under standard conditions or as recommended by the manufacturer. HATP·6HCl, magnesium acetate, ammonia, and sodium acetate were all commercially available reagents. HATP·6HCl was hexaaminotriphenylene hydrochloride, purchased from Jilin Zhongke Science & Technology Co., Ltd. HITP was 2,3,6,7,10,11-hexaaminotriphenylene ligand. Ammonia, with a mass fraction of 25-28 wt%, was purchased from Sinopharm Chemical Reagent Co., Ltd.
[0026] Example 1
[0027] A method for preparing a two-dimensional conductive metal-organic framework material includes the following steps:
[0028] (1) Solution preparation: Weigh 50 mg of 2,3,6,7,10,11-hexaaminotriphenylhexahydrochloride (HATP·6HCl), dissolve in 10 mL of deionized water to prepare an organic ligand solution with a concentration of 14 mmol / L. Separately weigh 64 mg of magnesium acetate tetrahydrate, dissolve in 10 mL of deionized water to prepare a metal salt solution with a concentration of 30 mmol / L.
[0029] (2) Mixing and reaction: Mix the two solutions in a 100 mL round-bottom flask. Then, slowly add 3 mL of a 6 mol / L ammonia solution to the mixed solution.
[0030] (3) Heating reaction: Fix the open flask in an oil bath and stir continuously at 85 °C for 2 hours.
[0031] (4) Post-processing: After the reaction was completed, the suspension was naturally cooled to room temperature. A white solid precipitate was obtained by centrifugation at 8000 rpm for 10 min. The precipitate was washed three times with deionized water. Finally, the solid was placed in a vacuum drying oven and dried at 65°C for 12 hours to obtain the dark purple powder target product, namely Mg3(HITP)2.
[0032] The two-dimensional conductive metal-organic framework material Mg3(HITP)2 obtained in this embodiment has a two-dimensional layered stacked structure. Magnesium defects and nitrogen vacancies exist in the two-dimensional conductive metal-organic framework material. The electron paramagnetic resonance (ERP) spectrum shows a significant signal peak at g = 2.00.
[0033] like Figure 1 Mg3(HITP)2 exhibits a layered nanostructure under a transmission electron microscope.
[0034] like Figure 2 Mg3(HITP)2 exhibits a layered structure under a scanning electron microscope.
[0035] like Figure 3 Mg3(HITP)2 exhibits sharp crystal diffraction peaks and displays layered structure diffraction peaks in the range of 25-30°.
[0036] like Figure 4 Mg3(HITP)2 at 1385 cm -1 And 1590 cm -1 Characteristic peaks of a graphene-like structure are present.
[0037] like Figure 5 The electron paramagnetic resonance (ERP) spectrum of Mg3(HITP)2 showed a significant signal peak at g = 2.00, which is considered to be due to the abundance of magnesium defects and nitrogen vacancies in the material.
[0038] Example 2
[0039] A method for preparing a two-dimensional conductive metal-organic framework material includes the following steps:
[0040] (1) Solution preparation: Weigh 50 mg of 2,3,6,7,10,11-hexaaminotriphenylhexahydrochloride (HATP·6HCl), dissolve in 10 mL of deionized water to prepare an organic ligand solution with a concentration of 14 mmol / L. Separately weigh 64 mg of magnesium acetate tetrahydrate, dissolve in 10 mL of deionized water to prepare a metal salt solution with a concentration of 30 mmol / L.
[0041] (2) Mixing and reaction: Mix the two solutions in a 100 mL round-bottom flask. Then, slowly add 3 mL of a 3 mol / L ammonia solution to the mixed solution.
[0042] (3) Heating reaction: Fix the open flask in an oil bath and stir continuously at 65 °C for 2 hours.
[0043] (4) Post-processing: After the reaction was completed, the suspension was naturally cooled to room temperature. A white solid precipitate was obtained by centrifugation at 8000 rpm for 10 min. The precipitate was washed three times with deionized water. Finally, the solid was placed in a vacuum drying oven and dried at 65°C for 12 hours to obtain the dark purple powder target product, namely Mg3(HITP)2.
[0044] The two-dimensional conductive metal-organic framework material Mg3(HITP)2 obtained in this embodiment has a two-dimensional layered stacked structure, and magnesium defects and nitrogen vacancies exist in the two-dimensional conductive metal-organic framework material.
[0045] Example 3
[0046] A method for preparing a two-dimensional conductive metal-organic framework material includes the following steps:
[0047] (1) Solution preparation: Weigh 50 mg of 2,3,6,7,10,11-hexaaminotriphenylhexahydrochloride (HATP·6HCl), dissolve in 10 mL of deionized water to prepare an organic ligand solution with a concentration of 14 mmol / L. Separately weigh 64 mg of magnesium acetate tetrahydrate, dissolve in 10 mL of deionized water to prepare a metal salt solution with a concentration of 30 mmol / L.
[0048] (2) Mixing and reaction: Mix the two solutions in a 100 mL round-bottom flask. Then, slowly add 5 mL of sodium acetate solution with a concentration of 4 mol / L to the mixed solution.
[0049] (3) Heating reaction: Fix the open flask in an oil bath and stir continuously at 85 °C for 4 hours.
[0050] (4) Post-processing: After the reaction was completed, the suspension was naturally cooled to room temperature. A white solid precipitate was obtained by centrifugation at 8000 rpm for 10 min. The precipitate was washed 5 times with deionized water. Finally, the solid was placed in a vacuum drying oven and dried at 65°C for 12 hours to obtain the dark purple powder target product, namely Mg3(HITP)2.
[0051] The two-dimensional conductive metal-organic framework material Mg3(HITP)2 obtained in this embodiment has a two-dimensional layered stacked structure, and magnesium defects and nitrogen vacancies exist in the two-dimensional conductive metal-organic framework material.
[0052] Example 4
[0053] A method for preparing a two-dimensional conductive metal-organic framework material includes the following steps:
[0054] (1) Solution preparation: Weigh 50 mg of 2,3,6,7,10,11-hexaaminotriphenylhexahydrochloride (HATP·6HCl), dissolve in 10 mL of deionized water to prepare an organic ligand solution with a concentration of 14 mmol / L. Separately weigh 64 mg of magnesium acetate tetrahydrate, dissolve in 10 mL of deionized water to prepare a metal salt solution with a concentration of 30 mmol / L.
[0055] (2) Mixing and reaction: Mix the two solutions in a 100 mL round-bottom flask. Then, slowly add 5 mL of 2 mol / L sodium acetate solution to the mixed solution.
[0056] (3) Heating reaction: Fix the open flask in an oil bath and stir continuously at 85 °C for 2 hours.
[0057] (4) Post-processing: After the reaction was completed, the suspension was naturally cooled to room temperature. A white solid precipitate was obtained by centrifugation at 8000 rpm for 10 min. The precipitate was washed 5 times with deionized water. Finally, the solid was placed in a vacuum drying oven and dried at 65°C for 12 hours to obtain the dark purple powder target product, namely Mg3(HITP)2.
[0058] The two-dimensional conductive metal-organic framework material Mg3(HITP)2 obtained in this embodiment has a two-dimensional layered stacked structure, and magnesium defects and nitrogen vacancies exist in the two-dimensional conductive metal-organic framework material.
[0059] Example 5
[0060] A method for preparing a two-dimensional conductive metal-organic framework material includes the following steps:
[0061] (1) Solution preparation: Weigh 32.0 mg of 2,3,6,7,10,11-hexaaminotriphenylhexahydrochloride (HATP·6HCl), dissolve it in 10 mL of deionized water, and prepare an organic ligand solution with a concentration of 9 mmol / L. Separately weigh 53.5 mg of magnesium acetate tetrahydrate, dissolve it in 10 mL of deionized water, and prepare a metal salt solution with a concentration of 25 mmol / L.
[0062] (2) Mixing and reaction: Mix the two solutions in a 100 mL round-bottom flask. Then, slowly add 4 mL of a 5 mol / L ammonia solution to the mixed solution.
[0063] (3) Heating reaction: Fix the open flask in an oil bath and stir continuously at 70 °C for 4 hours.
[0064] (4) Post-processing: After the reaction was completed, the suspension was naturally cooled to room temperature. A white solid precipitate was obtained by centrifugation at 8000 rpm for 10 min. The precipitate was washed four times with deionized water. Finally, the solid was placed in a vacuum drying oven and dried at 65°C for 12 hours to obtain the dark purple powder target product, namely Mg3(HITP)2.
[0065] Example 6
[0066] A method for preparing a two-dimensional conductive metal-organic framework material includes the following steps:
[0067] (1) Solution preparation: Weigh 453.2 mg of 2,3,6,7,10,11-hexaaminotriphenylene hexahydrochloride (HATP·6HCl), dissolve it in 10 mL of deionized water, and prepare an organic ligand solution with a concentration of 15 mmol / L. Separately weigh 85.6 mg of magnesium acetate tetrahydrate, dissolve it in 10 mL of deionized water, and prepare a metal salt solution with a concentration of 40 mmol / L.
[0068] (2) Mixing and reaction: Mix the two solutions in a 100 mL round-bottom flask. Then, slowly add 4 mL of 4 mol / L sodium acetate solution to the mixed solution.
[0069] (3) Heating reaction: Fix the open flask in an oil bath and stir continuously at 75 °C for 3 hours.
[0070] (4) Post-processing: After the reaction was completed, the suspension was naturally cooled to room temperature. A white solid precipitate was obtained by centrifugation at 8000 rpm for 10 min. The precipitate was washed three times with deionized water. Finally, the solid was placed in a vacuum drying oven and dried at 65°C for 12 hours to obtain the dark purple powder target product, namely Mg3(HITP)2.
[0071] Application Example 1
[0072] The Mg-MOF material prepared in Example 1 was used to fabricate a semiconductor gas sensor, and its comprehensive gas sensing performance was tested. The specific steps are as follows: 10 mg of Mg-MOF material was weighed and thoroughly ground (grinding time was 1 minute), then 3–4 drops of ethanol were added to prepare a uniform slurry. The resulting slurry was brushed onto the surface of an alumina ceramic substrate with gold / titanium interdigitated electrodes. After the sample dried, the sensor element was connected to the test circuit using solder and copper wires, and placed in a 1.8 L gas test chamber. The resistance changes of the Mg-MOF material were automatically recorded in real time using a Xiaoyu Electronics M2.0 gas sensing performance testing system.
[0073] During the test, different concentrations (1 ppm, 2 ppm, 5 ppm, 10 ppm, 20 ppm, 50 ppm, 100 ppm, 200 ppm) of NH3 gas were sequentially injected into the test chamber using a micro-syringe. As NH3 was introduced, the sensor resistance changed. After the resistance reached a stable state, the chamber was opened to expose the sensor to the air, and its resistance gradually returned to the initial value.
[0074] In this test, the sensitivity (responsivity) of the Mg-MOF material was defined as S = (Rg − Ra) / Ra, where Ra and Rg represent the resistance values of the Mg-MOF sensor in air and the test gas atmosphere, respectively. Response time and recovery time were defined as the time required for the sensor resistance change to reach 90% of the total change. The test results are as follows: Figure 5 As shown.
[0075] Depend on Figure 5 (a) and Figure 5 (c) It can be seen that the response value of Mg-MOF material to NH3 gradually increases with the increase of NH3 concentration, and shows a trend of saturation in the high concentration range; at room temperature, the sensitivity to 50 ppm NH3 is 39%.
[0076] Depend on Figure 5 (b) It can be seen that the response time and recovery time of Mg-MOF material to 50 ppm NH3 at room temperature are 12 s and 18 s, respectively.
[0077] Depend on Figure 5 (d) It can be seen that the Mg-MOF material exhibits a significantly higher response to NH3 gas than other interfering gases. Its sensitivity to NH3 is 39%, while the response values to toluene, methanol, ethanol, benzene and hydrogen are all less than 1%, indicating that the material has good gas selectivity.
[0078] Depend on Figure 5 (e) shows that, through fitting analysis of the response curve, the detection limit of Mg-MOF material for NH3 can reach the ppb level.
[0079] Of the above embodiments, the preferred embodiment is Embodiment 1.
[0080] Comparative Example 1
[0081] The remaining steps of this comparative example are the same as those in Example 1, except that the addition of a catalyst in step (2) is omitted. The results showed that the amount of product obtained was extremely small, and the sensor, after being fabricated, did not exhibit any response to ammonia.
[0082] Comparative Example 2
[0083] The remaining steps of this comparative example are the same as those in Example 1, except that the deionized water solvent in step (1) is replaced with N,N-dimethylformamide. The results showed that the final product was not a separable powder crystal product, but an amorphous flocculent.
[0084] Comparative Example 3
[0085] The remaining steps in this comparative example are the same as in Example 1, except that step (2) is omitted. It was found that replacing HATP·6HCl with 2,4,6-tris(2-pyridyl)-1,3,5-triazine resulted in the inability to prepare crystalline Mg-based two-dimensional conductive MOF materials.
Claims
1. A two-dimensional conductive metal-organic framework material, characterized in that: The chemical formula is Mg3(HITP)2, which has a two-dimensional layered stacked structure. The two-dimensional conductive metal-organic framework material contains magnesium defects and nitrogen vacancies.
2. A method for preparing a two-dimensional conductive metal-organic framework material, characterized in that: The hexaaminotriphenylene hydrochloride solution, magnesium acetate solution, and catalyst were stirred and mixed evenly. After stirring and reacting, the solid precipitate was collected by centrifugation, washed, and dried to obtain a two-dimensional conductive metal-organic framework material.
3. The method for preparing a two-dimensional conductive metal-organic framework material according to claim 2, characterized in that: The concentration of the hexaaminotriphenylene hydrochloride solution is 9-15 mmol / L, and the solvent is deionized water.
4. The method for preparing a two-dimensional conductive metal-organic framework material according to claim 2, characterized in that: The concentration of the magnesium acetate solution is 25-40 mmol / L, and the solvent is deionized water.
5. The method for preparing a two-dimensional conductive metal-organic framework material according to claim 2, characterized in that: The catalyst is an ammonia solution or a sodium acetate solution, and the solvent is deionized water.
6. The method for preparing a two-dimensional conductive metal-organic framework material according to claim 5, characterized in that: The concentration of the ammonia solution is 3-6 mol / L, and the concentration of the sodium acetate solution is 2-4 mol / L.
7. The method for preparing a two-dimensional conductive metal-organic framework material according to claim 1, characterized in that: The volume ratio of the hexaaminotriphenylene hydrochloride solution, magnesium acetate solution, and catalyst is 10:10:3~5.
8. The method for preparing a two-dimensional conductive metal-organic framework material according to claim 1, characterized in that: The stirring reaction is carried out at a temperature of 65-85°C for 2-4 hours.
9. The application of the two-dimensional conductive metal-organic framework material according to claim 1 in the sensing layer of a room temperature ammonia gas sensor.
10. The application of a two-dimensional conductive metal-organic framework material according to claim 9 in the sensing layer of a room temperature ammonia gas sensor, characterized in that: The sensing layer is coated on the surface of the gold interdigitated electrode, and the room temperature ammonia gas sensor has a response value of more than 39% for ammonia gas above 50 ppm.