Preparation method and application of In2O3-Co3O4 heterostructure material

Abstract

The invention discloses a preparation method and application of an In2O3-Co3O4 heterostructure material, an MOFs-MOFs heterojunction takes In-MOFs as a subject and ZIF-67 as an object, and epitaxial growth of an MOFs structure is realized. And the sensor is applied to ultra-sensitive gas sensing detection, so that acetoin detection in a low-power-consumption mode is realized. The constructed sensor has the characteristics of high sensitivity, high response and recovery speed, good selectivity and the like. The unique MOFs-MOFs structure increases the adsorption active sites of the composite material, and is beneficial to the improvement of the gas sensing performance. The successful preparation of the material provides a new strategy for reasonable preparation of MOFs derivatives. Technical reference is also provided for related chemical sensors such as electrochemiluminescence sensors and electrochemical sensors, and the method has wide potential use value.

Description

Technical Field

[0001] This application relates to an In 2 O 3 -Co 3 O 4 The invention relates to a preparation method and application of heterogeneous structure materials, belonging to the technical field of nano functional materials and environmental monitoring. Background Art

[0002] Listeriosis caused by Listeria monocytogenes is an infectious disease that can lead to a variety of diseases such as bacteremia, meningitis, and pregnancy complications. Therefore, accurate detection of Listeria monocytogenes in food is of great significance to human health. To detect Listeria monocytogenes, researchers usually use cell culture and biochemical tests, but these methods are limited to widespread use due to disadvantages such as labor-intensive, time-consuming procedures, complex operations, and expensive instruments. Therefore, there is an urgent need to seek a more efficient and low-cost way to achieve online detection of Listeria monocytogenes. Fortunately, previous studies have found that among the abundant metabolites of Listeria monocytogenes, acetoin (also known as 3-hydroxy-2-butanone) is the main gas species with an abundance of up to 32.2%, and the concentration of the released acetoin gas shows a good linear relationship with the growth time of Listeria monocytogenes. Therefore, acetoin can be regarded as a promising biomarker gas for tracking the content of Listeria monocytogenes in food. Furthermore, the presence of acetoin biomarker gas inspired researchers to develop portable, effective, and low-cost gas sensors for online monitoring of L. monocytogenes.

[0003] The core of gas sensors is the design and preparation of gas-sensitive materials. In recent years, porous metal organic frameworks (MOFs) are a new class of porous coordination polymers that are widely used in gas adsorption and separation, drug delivery, and heterogeneous catalysis. Due to their high porosity, large surface area, and tunable nanostructure, MOF materials have been proven to be favorable precursors for the easy preparation of porous metal oxides. The metal oxides obtained by MOFs also have porous properties, which will be beneficial to the gas mass transfer process. In addition, the large specific surface area provides a larger loading space for highly active reaction sites, ultimately achieving improved gas sensing performance.

[0004] Acetoin (also known as 3-hydroxy-2-butanone) is a metabolic biomarker gas for Listeria monocytogenes (a food pathogen). The sensitive and selective detection of acetoin biomarkers can achieve indirect online monitoring of Listeria monocytogenes. Traditional methods for detecting this bacterium are mainly based on cell culture and biochemical tests, but these methods require large equipment and professional operation, and the detection cost is very high, which is not conducive to its portable detection. Summary of the invention

[0005] Metal-organic frameworks (MOFs) are crystalline porous materials self-assembled by metal ions / clusters and organic ligands through coordination bonds. They have been a hot topic in the fields of chemistry and materials science in recent decades. Compared with traditional inorganic materials, MOFs have the characteristics of larger specific surface area, higher porosity, diverse structural types, and adjustable functions. In addition, the rich variety of organic ligands and metal nodes make MOFs highly plastic in terms of charge, polarity, chirality, redox potential, photoactivity, hydrophobicity / hydrophilicity, aromaticity / lipophilicity, stereochemistry, etc. Combining MOFs with MOFs can achieve the construction of materials with larger specific surface area, which is beneficial to the gas mass transfer process and the improvement of gas sensing performance.

[0006] The purpose of the present invention is to provide a method for preparing a MOFs-MOFs heterostructure gas sensing material with low cost and simple operation, and to use the heterostructure in a gas sensor to achieve rapid and sensitive detection of trace 3H-2B in production and life.

[0007] Based on this purpose, the present invention first prepares a new type of MOFs-MOFs heterostructure gas sensing material, and obtains its metal oxide through a subsequent pyrolysis process. Since it inherits the porous structure and large specific surface area of ​​its precursor, the material can realize the detection of trace acetoin (3H-2B) gas.

[0008] According to one aspect of the present application, there is provided an 2 O 3 -Co 3 O 4 A method for preparing a heterogeneous structure material, the method comprising the following steps:

[0009] (1) stirring a mixture I containing an indium precursor, an organic ligand, and a solvent I, reacting, centrifuging, and drying I to obtain In-MOF;

[0010] (2) stirring II and drying II a mixture II containing a cobalt precursor, 2-methylimidazole, In-MOF, and a solvent II to obtain an In-MOF-ZIF-67 heterostructure material;

[0011] (3) calcining the In-MOF-ZIF-67 heterostructure material to obtain the In 2 O 3 -Co 3 O 4 Heterogeneous structural materials.

[0012] Optionally, in step (1), the indium precursor is selected from at least one of indium chloride, indium acetylacetonate, indium acetate, and indium nitrate.

[0013] Optionally, in step (1), the organic ligand is selected from at least one of terephthalic acid, 2-chloroterephthalic acid, 2-aminoterephthalic acid, and 2-hydroxyterephthalic acid.

[0014] Optionally, the molar ratio of the indium precursor to the organic ligand is 0.5:1 to 1:0.5.

[0015] Optionally, the molar ratio of the indium precursor to the organic ligand is any value of 0.5:1, 1:1, 1:0.5, or a range between any two of the above.

[0016] Optionally, in step (2), the cobalt precursor is selected from at least one of cobalt chloride, cobalt acetylacetonate, cobalt acetate, and cobalt nitrate.

[0017] Optionally, the molar ratio of the 2-methylimidazole to the cobalt precursor is 0.5:1 to 1:0.5.

[0018] Optionally, the molar ratio of the 2-methylimidazole to the cobalt precursor is any value of 0.5:1, 1:1, 1:0.5, or a range between any two of the above.

[0019] Optionally, in the step (2), the molar ratio of the In-MOF to the cobalt precursor is 0.5:1 to 1:0.5.

[0020] Optionally, in step (1), the solvent I is selected from at least one of N,N-dimethylformamide, water and methanol.

[0021] Optionally, the molar volume ratio of the indium precursor to the solvent I is 0.5:1 to 1:0.5 mol:10 to 40 mL.

[0022] Optionally, the stirring time I is 1 to 5 hours.

[0023] Optionally, the reaction temperature is 100-130° C., and the reaction time is 3-6 hours.

[0024] Optionally, the centrifugation is performed 3 to 7 times.

[0025] Optionally, the drying I is freeze-drying.

[0026] Optionally, the freeze-drying temperature is -40 to -10°C, and the freeze-drying time is 12 to 24 hours.

[0027] Optionally, in step (2), the solvent II is selected from at least one of methanol, ethanol and water.

[0028] Optionally, the molar volume ratio of the cobalt precursor to the solvent II is 0.5:1 to 1:0.5 mol:30 to 50 mL.

[0029] Optionally, the stirring time II is 4 to 6 hours.

[0030] Optionally, the temperature of the drying II is 30 to 80° C., and the time of the drying II is 10 to 18 hours.

[0031] Optionally, in step (2), the calcination temperature is 300-500° C., and the calcination time is 3-5 hours.

[0032] Optionally, the reaction further includes washing the material, and the solvent is selected from at least one of water, ethanol and methanol.

[0033] According to another aspect of the present application, there is provided an In prepared by the above-mentioned preparation method 2 O 3 -Co 3 O 4 Heterostructure materials, the In 2 O 3 -Co 3 O 4 The heterostructure material is obtained by calcining the In-MOF-ZIF-67 heterostructure material;

[0034] The In-MOF-ZIF-67 heterostructure material includes a host and a guest, the host is In-MOF, and the guest is ZIF-67.

[0035] Optionally, the In-MOF and ZIF-67 account for 5wt% to 30wt% of the MOFs-MOFs heterostructure material.

[0036] According to another aspect of the present application, there is provided an In 2 O 3 -Co3 O 4 Application of heterostructure materials in acetoin gas sensors.

[0037] Optionally, the detection limit of the acetoin gas sensor for acetoin is 460-600 ppb.

[0038] Optionally, the operating temperature of the acetoin gas sensor is 120°C to 140°C.

[0039] As a specific implementation, the present application is implemented through the following technical solutions:

[0040] 1. Preparation of a MOFs-MOFs heterostructure gas sensing material and its application in 3H-2B gas sensing, the preparation method comprising the following preparation steps:

[0041] Step a, preparing MOFs-MOFs heterostructure gas sensing materials;

[0042] Step b, constructing a 3H-2B gas sensor;

[0043] Among them, the specific steps of step a for preparing MOFs-MOFs heterostructure gas sensing material are:

[0044] (1) Preparation of In-MOFs

[0045] First, a certain amount of indium precursor and a certain amount of organic ligand were added to 20 mL of DMF. The solution was mixed and vigorously stirred with a magnetic stirrer at room temperature for 1 to 3 hours, and then placed in a hydrothermal synthesis reactor, which was placed in an oven at a heating temperature of 100 to 130 ° C for 3 to 6 hours. After heating, the mixture was cooled to room temperature, centrifuged three times with ethanol, then centrifuged three times with high-purity water, and freeze-dried for 15 minutes to obtain uncalcined In-MOF.

[0046] (2) Preparation of In-MOFs-ZIF-67 heterostructures

[0047] A certain amount of 2-methylimidazole was added to the methanol solution containing the product of (1) and stirred to obtain a uniform solution. Then, another 5 mL of methanol containing a certain amount of cobalt precursor was injected into the above solution and further stirred at room temperature for 4 to 6 hours. Finally, it was dried at 60°C overnight for further use.

[0048] (3)In 2 O 3 -Co 3 O 4 Preparation of heterostructures

[0049] The product of (2) is placed in a muffle furnace and calcined at a temperature of 300-500°C for 3-5 hours. 2 O 3 -Co 3 O 4 Heterogeneous structure.

[0050] Step b: The specific construction steps for constructing the 3H-2B gas sensor are:

[0051] (1) Using the interdigital electrode as the gas sensing electrode, add the prepared sample to an appropriate amount of solvent and mix to form a uniform slurry. Evenly drop the slurry on the electrode surface to form a film. Dry the interdigital electrode in an oven to evaporate the solvent to obtain a sensing film.

[0052] (2) The electrode obtained in step (1) is then aged in an oven to remove the organic solvent remaining on the electrode, thereby obtaining a gas sensing electrode with stable resistance. The gas sensing electrode is connected to a test instrument to obtain a 3H-2B gas sensor.

[0053] Optionally, in step (1), the solvent is selected from at least one of ultrapure water, anhydrous ethanol, and acetone.

[0054] 2. The gas sensor based on the two-dimensional metal oxide gas-sensitive material is applied to the detection of 3H-2B gas molecules, and its characteristics are that the specific detection method is:

[0055] (1) Using interdigital electrodes as gas sensing electrodes, 5-10 μL of slurry was dropped onto the surface of the substrate with Ag-Pd printed interdigital electrodes. The electrodes were dried at 65-100°C to form a sensing film.

[0056] (2) The modified interdigital electrode is heated in an oven to 180-200° C. for 12-24 hours to remove the residual organic solvent, thereby obtaining a 3H-2B gas sensor to be tested.

[0057] (3) The gas sensing test is carried out using the static gas distribution method, that is, a certain amount of 3H-2B liquid is evaporated on a hot stage using a micro-injector to obtain a certain concentration of 3H-2B gas. The vaporized 3H-2B gas evaporates in the test chamber, and the 3H-2B gas molecules are detected by recording the resistance change of the sensor before and after the gas is introduced.

[0058] (4) Record the initial resistance of the sensor in air as R a , different concentrations of 3H-2B were introduced into the test chamber, and the resistance when the gas was introduced was recorded as R g , with R g With R aA working curve is drawn based on the relationship between the ratio and the concentration of 3H-2B gas molecules.

[0059] In the present application, the MOFs-MOFs heterojunction is based on In-MOFs and ZIF-67 as the object to achieve epitaxial growth of the MOFs structure. It is used in ultra-sensitive gas sensing detection to achieve the detection of 3H-2B in low power consumption mode. The constructed sensor has the characteristics of high sensitivity, fast response recovery speed, and good selectivity. The unique MOFs-MOFs structure increases the adsorption active sites of the composite material, which is beneficial to the improvement of gas sensing performance. The successful preparation of this material provides a new strategy for the rational preparation of MOFs derivatives. It also provides technical references for related chemical sensors, such as electrochemiluminescence sensors, electrochemical sensors, etc., and has a wide range of potential use value.

[0060] The beneficial effects of this application include:

[0061] 1) The 3H-2B gas sensor provided in this application is simple to prepare and easy to operate, and can achieve rapid, sensitive, and highly selective detection of 3H-2B gas molecules at a low cost. In addition, the test conditions close to room temperature provide conditions for portable detection of the sensor, which has market development prospects.

[0062] 2) The present application provides a method for preparing a MOFs-MOFs heterostructure. The preparation method is simple and uses a "one-pot method" to achieve controllable preparation of the material.

[0063] 3) The growth of the MOFs-MOFs heterostructure provided in the present application is carried out in an epitaxial growth mode due to lattice parameter matching, which greatly reduces its lattice distortion.

[0064] 4) The porous metal oxide with a large specific surface area obtained by in-situ pyrolysis of MOFs heterostructures provided in this application provides a new strategy for the preparation of gas sensing materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] Figure 1 This is the XRD pattern of the MOFs-MOFs heterostructure gas sensing material prepared in Example 1 of the present application.

[0066] Figure 2 In prepared in Example 1 of the present application 2 O 3 -Co 3 O 4 Heterostructure XRD pattern.

[0067] Figure 3 This is a working curve diagram of the gas sensor in Example 12 of the present application. DETAILED DESCRIPTION

[0068] The present application is described in detail below with reference to embodiments, but the present application is not limited to these embodiments.

[0069] Unless otherwise specified, the raw materials in the examples of this application were purchased through commercial channels.

[0070] In the examples of the present application, the instruments used to characterize the MOFs-MOFs heterostructure gas sensing material are as follows:

[0071] Instrument Model Manufacturer RX I Fourier Transform Infrared Spectrometer Perkin Elmer Model Smart Lab SE XRD Nippon Rigaku Co., Ltd. Gemini 300 Field Emission Scanning Electron Microscope Carl Zeiss AG Optical and electrical integrated test platform CGS-MT KQ3200DB CNC Ultrasonic Cleaner Kunshan Ultrasonic Instrument Co., Ltd.

[0072] Example 1 Preparation of MOFs-MOFs heterostructure gas sensing materials

[0073] (1) Preparation of In-MOFs

[0074] First, 0.6 g of indium chloride and 0.6 g of 2-chloroterephthalic acid were added to 20 mL of DMF. The solution was mixed and vigorously stirred with a magnetic stirrer at room temperature for 2.5 hours, and then placed in a hydrothermal synthesis reactor, which was placed in an oven at a heating temperature of 100 ° C for 4 hours. After heating, the mixture was cooled to room temperature, centrifuged three times with ethanol, then centrifuged three times with high-purity water, and freeze-dried for 15 minutes to obtain uncalcined In-MOF.

[0075] (2) Preparation of In-MOFs-ZIF-67MOFs-MOFs heterostructures

[0076] 0.3 g of 2-methylimidazole was added to the methanol solution containing the product of (1) and stirred to obtain a uniform solution. Then, another 5 mL of methanol solution containing 0.3 g of cobalt nitrate was injected into the above solution and further stirred at room temperature for 4 hours. Finally, it was dried at 60°C overnight for further use.

[0077] (3)In 2 O 3 -Co 3 O 4 Preparation of heterostructures

[0078] The product in (2) was calcined in a muffle furnace at a temperature of 500°C for 3 hours. 2 O 3 -Co 3 O 4 Heterogeneous structure. Figure 1 It can be seen that In MOFs-Co-MOFs was successfully synthesized. Figure 2 It can be seen that In 2 O 3-Co 3 O 4 The synthesis was successful.

[0079] Example 2 Preparation of MOFs-MOFs heterostructure gas sensing materials rich in oxygen defects

[0080] (1) Preparation of In-MOFs

[0081] First, 0.4 g of indium nitrate and 0.4 g of 2-chloroterephthalic acid were added to 20 mL of DMF. The solution was mixed and vigorously stirred with a magnetic stirrer at room temperature for 2.5 hours, and then placed in a hydrothermal synthesis reactor, which was placed in an oven at a heating temperature of 100 ° C for 5 hours. After heating, the mixture was cooled to room temperature, centrifuged three times with ethanol, then centrifuged three times with high-purity water, and freeze-dried for 15 minutes to obtain uncalcined In-MOF.

[0082] (2) Preparation of In-MOFs-ZIF-67MOFs-MOFs heterostructures

[0083] 0.3 g of 2-methylimidazole was added to the methanol solution containing the product of (1) and stirred to obtain a uniform solution. Then, another 5 mL of methanol solution containing 0.3 g of cobalt nitrate was injected into the above solution and further stirred at room temperature for 4 hours. Finally, it was dried at 60°C overnight for further use.

[0084] (3)In 2 O 3 -Co 3 O 4 Preparation of heterostructures

[0085] The product in (2) was calcined in a muffle furnace at a temperature of 500°C for 3 hours. 2 O 3 -Co 3 O 4 Heterogeneous structure.

[0086] Example 3 Preparation of MOFs-MOFs heterostructure gas sensing materials rich in oxygen defects

[0087] (1) Preparation of In-MOFs

[0088] First, 0.6 g of indium nitrate and 0.6 g of terephthalic acid were added to 20 mL of DMF. The solution was mixed and vigorously stirred with a magnetic stirrer at room temperature for 2.5 hours, and then placed in a hydrothermal synthesis reactor, which was placed in an oven at a heating temperature of 100 ° C for 4 hours. After heating, the mixture was cooled to room temperature, centrifuged three times with ethanol, then centrifuged three times with high-purity water, and freeze-dried for 15 minutes to obtain uncalcined In-MOF.

[0089] (2) Preparation of In-MOFs-ZIF-67MOFs-MOFs heterostructures

[0090] 0.3 g of 2-methylimidazole was added to the methanol solution containing the product of (1) and stirred to obtain a uniform solution. Then, another 5 mL of methanol solution containing 0.3 g of cobalt nitrate was injected into the above solution and further stirred at room temperature for 4 hours. Finally, it was dried at 60°C overnight for further use.

[0091] (3)In 2 O 3 -Co 3 O 4 Preparation of heterostructures

[0092] The product in (2) was calcined in a muffle furnace at a temperature of 500°C for 3 hours. 2 O 3 -Co 3 O 4 Heterogeneous structure.

[0093] Example 4 Preparation of MOFs-MOFs heterostructure gas sensing materials rich in oxygen defects

[0094] (1) Preparation of In-MOFs

[0095] First, 1.2 g of indium nitrate and 1.2 g of terephthalic acid were added to 20 mL of DMF. The solution was mixed and vigorously stirred with a magnetic stirrer at room temperature for 2.5 hours, and then placed in a hydrothermal synthesis reactor, which was placed in an oven at a heating temperature of 110 ° C for 6 hours. After heating, the mixture was cooled to room temperature, centrifuged three times with ethanol, then centrifuged three times with high-purity water, and freeze-dried for 15 minutes to obtain uncalcined In-MOF.

[0096] (2) Preparation of In-MOFs-ZIF-67MOFs-MOFs heterostructures

[0097] 0.3 g of 2-methylimidazole was added to the methanol solution containing the product of (1) and stirred to obtain a uniform solution. Then, another 5 mL of methanol solution containing 0.3 g of cobalt nitrate was injected into the above solution and further stirred at room temperature for 4 hours. Finally, it was dried at 60°C overnight for further use.

[0098] (3)In 2 O 3 -Co 3 O 4 Preparation of heterostructures

[0099] The product in (2) was calcined in a muffle furnace at a temperature of 500°C for 3 hours. 2 O 3 -Co 3 O 4 Heterogeneous structure.

[0100] Example 5 Preparation of MOFs-MOFs heterostructure gas sensing materials rich in oxygen defects

[0101] (1) Preparation of In-MOFs

[0102] First, 0.6 g of indium nitrate and 0.6 g of 2-aminoterephthalic acid were added to 20 mL of DMF. The solution was mixed and vigorously stirred with a magnetic stirrer at room temperature for 2.5 hours, and then placed in a hydrothermal synthesis reactor, which was placed in an oven at a heating temperature of 120 ° C for 4 hours. After heating, the mixture was cooled to room temperature, centrifuged three times with ethanol, then centrifuged three times with high-purity water, and freeze-dried for 15 minutes to obtain uncalcined In-MOF.

[0103] (2) Preparation of In-MOFs-ZIF-67MOFs-MOFs heterostructures

[0104] 0.3 g of 2-methylimidazole was added to the methanol solution containing the product of (1) and stirred to obtain a uniform solution. Then, another 5 mL of methanol solution containing 0.3 g of cobalt nitrate was injected into the above solution and further stirred at room temperature for 4 hours. Finally, it was dried at 60°C overnight for further use.

[0105] (3)In 2 O 3 -Co 3 O 4 Preparation of heterostructures

[0106] The product in (2) was calcined in a muffle furnace at a temperature of 500°C for 3 hours. 2 O 3 -Co 3 O 4 Heterogeneous structure.

[0107] Example 6

[0108] (1) Preparation of In-MOFs

[0109] First, 0.6 g of indium acetate and 0.6 g of 2-aminoterephthalic acid were added to 20 mL of DMF. The solution was mixed and vigorously stirred with a magnetic stirrer at room temperature for 2.5 hours, and then placed in a hydrothermal synthesis reactor, which was placed in an oven at a heating temperature of 120 ° C for 4 hours. After heating, the mixture was cooled to room temperature, centrifuged three times with ethanol, then centrifuged three times with high-purity water, and freeze-dried for 15 minutes to obtain uncalcined In-MOF.

[0110] (2) Preparation of In-MOFs-ZIF-67MOFs-MOFs heterostructures

[0111] 0.3 g of 2-methylimidazole was added to the methanol solution containing the product of (1) and stirred to obtain a uniform solution. Then, another 5 mL of methanol solution containing 0.3 g of cobalt nitrate was injected into the above solution and further stirred at room temperature for 4 hours. Finally, it was dried at 60°C overnight for further use.

[0112] (3)In 2 O 3 -Co 3 O 4 Preparation of heterostructures

[0113] The product in (2) was calcined in a muffle furnace at a temperature of 500°C for 3 hours. 2 O 3 -Co 3 O 4 Heterogeneous structure.

[0114] Example 7

[0115] (1) Preparation of In-MOFs

[0116] First, 0.6 g of indium acetate and 0.6 g of 2-hydroxyterephthalic acid were added to 20 mL of DMF. The solution was mixed and vigorously stirred with a magnetic stirrer at room temperature for 2.5 hours, and then placed in a hydrothermal synthesis reactor, which was placed in an oven at a heating temperature of 110 ° C for 4 hours. After heating, the mixture was cooled to room temperature, centrifuged three times with ethanol, then centrifuged three times with high-purity water, and freeze-dried for 15 minutes to obtain uncalcined In-MOF.

[0117] (2) Preparation of In-MOFs-ZIF-67MOFs-MOFs heterostructures

[0118] 0.3 g of 2-methylimidazole was added to the methanol solution containing the product of (1) and stirred to obtain a uniform solution. Then, another 5 mL of methanol solution containing 0.3 g of cobalt nitrate was injected into the above solution and further stirred at room temperature for 4 hours. Finally, it was dried at 60°C overnight for further use.

[0119] (3)In 2 O 3 -Co 3 O 4 Preparation of heterostructures

[0120] The product in (2) was calcined in a muffle furnace at a temperature of 500°C for 3 hours. 2 O 3 -Co 3 O 4 Heterogeneous structure.

[0121] Example 8

[0122] (1) Preparation of In-MOFs

[0123] First, 0.6 g of indium acetylacetonate and 0.6 g of 2-hydroxyterephthalic acid were added to 20 mL of DMF. The solution was mixed and vigorously stirred with a magnetic stirrer at room temperature for 2.5 hours, and then placed in a hydrothermal synthesis reactor, which was placed in an oven at a heating temperature of 110 ° C for 4 hours. After heating, the mixture was cooled to room temperature, centrifuged three times with ethanol, then centrifuged three times with high-purity water, and freeze-dried for 15 minutes to obtain uncalcined In-MOF.

[0124] (2) Preparation of In-MOFs-ZIF-67MOFs-MOFs heterostructures

[0125] 0.3 g of 2-methylimidazole was added to the methanol solution containing the product of (1) and stirred to obtain a uniform solution. Then, another 5 mL of methanol solution containing 0.3 g of cobalt nitrate was injected into the above solution and further stirred at room temperature for 4 hours. Finally, it was dried at 60°C overnight for further use.

[0126] (3)In 2 O 3 -Co 3 O 4 Preparation of heterostructures

[0127] The product in (2) was calcined in a muffle furnace at a temperature of 500°C for 3 hours. 2 O 3 -Co 3 O 4 Heterogeneous structure.

[0128] Example 9 Construction of 3H-2B gas sensor

[0129] (1) Using the interdigital electrode as the gas sensing electrode, the MOFs-MOFs heterostructure gas sensing material prepared in Example 1 was added to an appropriate amount of water and mixed to form a uniform slurry. Then 10 μL of the slurry was dropped on the surface of the substrate with Ag-Pd printed interdigital electrodes. The electrode was dried at 80°C to form a sensing film.

[0130] (2) The electrode obtained in step (1) was then heated to 200° C. in an oven for 5 hours to remove the residual organic solvent, thereby obtaining a 3H-2B gas sensor.

[0131] Example 10 Construction of 3H-2B gas sensor

[0132] (1) Using the interdigital electrode as the gas sensing electrode, the MOFs-MOFs heterostructure gas sensing material prepared in Example 3 was added to an appropriate amount of anhydrous ethanol and mixed to form a uniform slurry. Then 5 μL of the slurry was dropped on the surface of the substrate with Ag-Pd printed interdigital electrodes. The electrode was dried at 60°C to form a sensing film.

[0133] (2) The electrode obtained in step (1) was then heated to 180° C. in an oven for 3 hours to remove the residual organic solvent, thereby obtaining a 3H-2B gas sensor.

[0134] Embodiment 11

[0135] The 3H-2B gas sensors prepared in Examples 9 and 10 are applied to the detection of 3H-2B gas molecules, and the steps are as follows:

[0136] (1) Preparation of gas sensing electrode: The 3H-2B gas sensor constructed in Example 9 was used as the working electrode;

[0137] (2) Standard gas configuration: To obtain the required gas, 3H-2B liquid was added into the test chamber using a micro syringe and evaporated directly;

[0138] (3) Drawing a working curve: Connect the electrode described in (1) to a gas sensor detection device, and distribute gas in a gas chamber using the method described in (2); test the resistance of the sensor before and after ventilation in a chamber with constant relative humidity and temperature; draw a working curve based on the relationship between the obtained resistance change and the 3H-2B concentration; the resistance change is measured by R g / R a In other words, Ra refers to the resistance in the ambient air, and R g is the resistance in the measured gas; the working curve takes the concentration of 3H-2B gas molecules as the horizontal axis, Rg / R a Draw for the vertical axis.

[0139] Example 12

[0140] Inject interfering gas molecules with the same concentration as 3H-2B into the chamber, test their gas-sensitive properties, and obtain the selectivity of the sensor. (The test method and test conditions are consistent with 3H-2B gas detection); Figure 3 It can be seen that the sensor has a good response.

[0141] The above are only a few embodiments of the present application and do not constitute any form of limitation to the present application. Although the present application is disclosed as above with preferred embodiments, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for preparing an In2O3-Co3O4 heterostructure material, characterized in that: The preparation method comprises the following steps: (1) stirring a mixture I containing an indium precursor, an organic ligand, and a solvent I, reacting, centrifuging, and drying I to obtain In-MOF; (2) stirring II and drying II a mixture II containing a cobalt precursor, 2-methylimidazole, In-MOF, and a solvent II to obtain an In-MOF-ZIF-67 heterostructure material; (3) calcining the In-MOF-ZIF-67 heterostructure material to obtain the In2O3-Co3O4 heterostructure material.

2. The preparation method according to claim 1, characterized in that: In the step (1), the indium precursor is selected from at least one of indium chloride, indium acetylacetonate, indium acetate, and indium nitrate; Preferably, in step (1), the organic ligand is selected from at least one of terephthalic acid, 2-chloroterephthalic acid, 2-aminoterephthalic acid, and 2-hydroxyterephthalic acid; Preferably, the molar ratio of the indium precursor to the organic ligand is 0.5:1 to 1:0.

5.

3. The preparation method according to claim 1, characterized in that: In the step (2), the cobalt precursor is selected from at least one of cobalt chloride, cobalt acetylacetonate, cobalt acetate, and cobalt nitrate; Preferably, the molar ratio of the 2-methylimidazole to the cobalt precursor is 0.5:1 to 1:0.5; Preferably, in the step (2), the molar ratio of the In-MOF to the cobalt precursor is 0.5:1 to 1:0.

5.

4. The preparation method according to claim 1, characterized in that: In the step (1), the solvent I is selected from at least one of N,N-dimethylformamide, water, and methanol; Preferably, the molar volume ratio of the indium precursor to the solvent I is 0.5:1 to 1:0.5 mol:10 to 40 mL; Preferably, the stirring time I is 1 to 5 hours; Preferably, the reaction temperature is 100-130°C and the reaction time is 3-6h; Preferably, the number of centrifugation is 3 to 7 times; Preferably, the drying I is freeze drying; Preferably, the freeze-drying temperature is -40 to -10°C, and the freeze-drying time is 12 to 24 hours.

5. The preparation method according to claim 1, characterized in that: In the step (2), the solvent II is selected from at least one of methanol, ethanol and water; Preferably, the molar volume ratio of the cobalt precursor to the solvent II is 0.5:1 to 1:0.5 mol:30 to 50 mL; Preferably, the stirring time II is 4 to 6 hours; Preferably, the temperature of the drying II is 30 to 80° C., and the time of the drying II is 10 to 18 hours.

6. The preparation method according to claim 1, characterized in that: In the step (3), the calcination temperature is 300 to 500° C., and the calcination time is 3 to 5 hours.

7. The In2O3-Co3O4 heterostructure material prepared by the preparation method according to any one of claims 1 to 6, characterized in that: The In2O3-Co3O4 heterostructure material is obtained by calcining the In-MOF-ZIF-67 heterostructure material; The In-MOF-ZIF-67 heterostructure material includes a host and a guest, the host is In-MOF, and the guest is ZIF-67.

8. The In2O3-Co3O4 heterostructure material according to claim 7, characterized in that: The In-MOF and ZIF-67 account for 5 wt % to 30 wt % of the MOFs-MOFs heterostructure material.

9. Use of the In2O3-Co3O4 heterostructure material according to any one of claims 7 to 8 in an acetoin gas sensor.

10. The use according to claim 9, characterized in that: The detection limit of the acetoin gas sensor for acetoin is 460-600 ppb; Preferably, the operating temperature of the acetoin gas sensor is 120°C to 140°C.

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