Method for manufacturing triethylamine gas sensor based on MOF-derived In2O3 gas-sensitive material

Abstract

The invention discloses a manufacturing method of a triethylamine gas sensor based on an MOF (Metal Organic Framework) derived In2O3 gas sensitive material. The MOF-derived In2O3 gas sensitive material is synthesized by adopting a solvothermal method. The morphology of the In2O3 material is regulated and controlled by changing the reaction temperature, the obtained MOF-In2O3-150 DEG C gas sensitive material is small in particle size and has a more developed gap structure, the sensitivity of a sensor to triethylamine gas is effectively improved, and the gas sensitive material has excellent selectivity and low detection limit. The gas sensitive material develops a wider prospect for detecting triethylamine gas.

Description

Technical Field

[0001] The present invention belongs to the technical field of metal oxide semiconductor gas sensors, and in particular relates to a method for manufacturing a triethylamine gas sensor based on MOF-derived In2O3 gas-sensitive material. Technical Background

[0002] Triethylamine (TEA) is a colorless, transparent liquid. As an organic amine, it is an important industrial material and is widely used as a catalyst, preservative, and other materials. However, triethylamine is extremely irritating, causing irritation to the skin, eyes, and respiratory system. Once inhaled into the lungs, it can cause pulmonary edema and even death. According to the Occupational Safety and Health Administration (OSHA), the permissible triethylamine concentration in air is limited to 10 ppm. The American Conference of Governmental Industrial Hygienists recommends a triethylamine threshold of 1 ppm, and the European Commission also recommends an occupational exposure limit of 1 ppm (8-hour total water exposure). Therefore, it is of great significance to design highly sensitive and selective sensors to detect trace amounts of triethylamine gas in the ambient environment.

[0003] Metal oxide semiconductor (MOS) sensors are a class of sensors with a long research history and high application potential. They offer advantages such as high sensitivity, fast response / recovery, low cost, and ease of fabrication, making them widely used in the detection of toxic and hazardous gases. Indium oxide (In2O3) is an N-type metal oxide semiconductor sensing material with a wide bandgap (3.55–3.75 eV) and high conductivity. Its low resistivity and abundant surface defects have attracted considerable attention for its application in gas sensors. In recent years, metal-organic frameworks (MOFs), with their high specific surface area, tunable structure, and controllable porosity, have significantly advanced various application areas. Inspired by these outstanding properties, MOFs have been studied in gas sensors and have demonstrated excellent gas selectivity. Summary of the Invention

[0004] The present invention aims to provide a method for fabricating a triethylamine gas sensor based on a MOF-derived In2O3 gas-sensitive material. The gas sensor prepared by the present invention not only has high sensitivity, but also has a low detection limit and excellent selectivity.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A method for preparing a triethylamine gas sensor based on MOF-derived In2O3 gas-sensitive material, the method comprising the following steps:

[0007] (1) Dissolve 1.202 g of In(NO3)3·xH2O in 10–20 ml of N,N-dimethylformamide and stir for 5–10 minutes to prepare solution A. Dissolve 0.166 g of 1,4-benzenedicarboxylic acid in 10–20 ml of N,N-dimethylformamide and stir for 5–10 minutes to prepare solution B.

[0008] (2) Solution A and Solution B are mixed and stirred for 10 to 20 minutes, and then transferred to a polytetrafluoroethylene-lined stainless steel autoclave, sealed, and maintained at 100 to 200° C. for 10 to 15 hours; the autoclave is naturally cooled to room temperature, and then centrifuged and washed to collect the precipitate, and the product is dried in an oven at 70 to 90° C. for 10 to 15 hours to obtain a solid powder;

[0009] (3) calcining the solid powder obtained in step (2) in air at 390-420° C. for 1.0-3.0 hours at a heating rate of 1-4° C. / min to obtain a MOF-derived In2O3 gas-sensitive material;

[0010] (4) taking an appropriate amount of the MOF-derived In2O3 gas-sensitive material obtained in step (3) and placing it in an agate mortar, adding 1 to 2 drops of distilled water, grinding it into a paste, and then evenly coating it on the outer surface of the ceramic tube to form a uniform gas-sensitive material film on the outer surface of the ceramic tube; wherein the ceramic tube has been welded to the sensor base in advance, and a nickel-chromium (Ni-Cr) heating wire that provides the appropriate operating temperature for the element passes through the ceramic tube and is also welded to the base;

[0011] (5) After the film on the outer surface of the ceramic tube is allowed to stand at room temperature for 1 to 2 days and naturally dried, it is aged at 100 to 200 mA for 2 to 3 days to prepare a gas sensor and perform a gas sensing performance test.

[0012] The method for preparing a triethylamine gas sensor based on MOF-derived In2O3 gas-sensitive material of the present invention has the following advantages:

[0013] (1) The present invention uses N,N-dimethylformamide as a solvent, In(NO3)3·xH2O as a metal ion source, and 1,4-benzenedicarboxylic acid as an organic ligand, and utilizes a simple and low-cost solvent thermal method to synthesize an In-MOF precursor, and obtains a MOF-derived In2O3 gas-sensitive material by high-temperature calcination.

[0014] (2) The gas sensor based on the MOF-derived In2O3 gas-sensitive material prepared by the present invention has a sensitivity of 60 to 90 to 10 ppm of triethylamine at an optimal operating temperature of 150°C. The detection limit of the gas sensor is 0.5 ppm. (3) The gas sensor based on the MOF-derived In2O3 gas-sensitive material prepared by the present invention has excellent selectivity and high sensitivity to triethylamine gas through testing of triethylamine, ethanol, n-butanol, acetone, and formaldehyde gases. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The sensitivity of gas sensors prepared with MOF-In2O3-120, MOF-In2O3-150, and MOF-In2O3-180 gas-sensitive materials to 10 ppm triethylamine changes with different operating temperatures;

[0016] Figure 2 Selectivity bar graph of the sensor made of MOF-In2O3-150 gas sensitive material to triethylamine, ethanol, n-butanol, acetone, and formaldehyde gases at a concentration of 20 ppm at the optimal working temperature of 150°C. DETAILED DESCRIPTION

[0017] Example 1:

[0018] 1. Dissolve 1.202 g of In(NO3)3·xH2O in 15 ml of N,N-dimethylformamide and stir for 10 minutes to prepare solution A. Dissolve 0.166 g of 1,4-benzenedicarboxylic acid in 15 ml of N,N-dimethylformamide and stir for 10 minutes to prepare solution B.

[0019] 2. Solution A and Solution B were mixed and stirred for 15 minutes, then transferred to a polytetrafluoroethylene-lined stainless steel autoclave, sealed, and maintained at 120°C for 12 hours; the autoclave was naturally cooled to room temperature, and the precipitate was collected by centrifugation and washing, and the product was dried in an oven at 80°C for 12 hours to obtain a solid powder;

[0020] 3. The solid powder obtained in step 2 was calcined in air at 400°C for 2 hours at a heating rate of 2°C / min to obtain a MOF-In2O3-120 gas-sensitive material;

[0021] 4. Take 20 mg of the MOF-In2O3-120 gas-sensitive material obtained in step 3 and place it in an agate mortar. Add 2 drops of distilled water and grind it into a paste. Then evenly apply it to the outer surface of the ceramic tube to form a uniform gas-sensitive material film on the outer surface of the ceramic tube. The ceramic tube has been welded to the sensor base in advance. A nickel-chromium (Ni-Cr) heating wire that provides the appropriate operating temperature for the element passes through the ceramic tube and is also welded to the base.

[0022] 5. Let the gas-sensitive material film coated on the outer surface of the ceramic tube stand at room temperature for 1 day to dry naturally. After aging at 100mA for 24 hours, and then aging at 180mA for 24 hours, the gas sensor is prepared and the gas-sensing performance is tested.

[0023] Example 2:

[0024] 4. Dissolve 1.202 g of In(NO3)3·xH2O in 15 ml of N,N-dimethylformamide and stir for 10 minutes to prepare solution A. Dissolve 0.166 g of 1,4-benzenedicarboxylic acid in 15 ml of N,N-dimethylformamide and stir for 10 minutes to prepare solution B.

[0025] 5. Mix solution A and solution B evenly and stir for 15 minutes, then transfer to a polytetrafluoroethylene-lined stainless steel autoclave, seal it and keep it at 150°C for 12 hours; after the autoclave is naturally cooled to room temperature, centrifuge and wash to collect the precipitate, and dry the product in an oven at 80°C for 12 hours to obtain a solid powder;

[0026] 6. The solid powder obtained in step 2 was calcined in air at 400°C for 2 hours at a heating rate of 2°C / min to obtain a MOF-In2O3-150 gas-sensitive material;

[0027] 4. Take 20 mg of the MOF-In2O3-150 gas-sensitive material obtained in step 3 and place it in an agate mortar. Add 2 drops of distilled water and grind it into a paste. Then evenly apply it to the outer surface of the ceramic tube to form a uniform gas-sensitive material film on the outer surface of the ceramic tube. The ceramic tube has been welded to the sensor base in advance. A nickel-chromium (Ni-Cr) heating wire that provides the appropriate operating temperature for the element passes through the ceramic tube and is also welded to the base.

[0028] 5. Let the gas-sensitive material film coated on the outer surface of the ceramic tube stand at room temperature for 1 day to dry naturally. After aging at 100mA for 24 hours, and then aging at 180mA for 24 hours, the gas sensor is prepared and the gas-sensing performance is tested.

[0029] Example 3:

[0030] 7. Dissolve 1.202 g of In(NO3)3·xH2O in 15 ml of N,N-dimethylformamide and stir for 10 minutes to prepare solution A. Dissolve 0.166 g of 1,4-benzenedicarboxylic acid in 15 ml of N,N-dimethylformamide and stir for 10 minutes to prepare solution B.

[0031] 8. Mix solution A and solution B evenly and stir for 15 minutes, then transfer to a polytetrafluoroethylene-lined stainless steel autoclave, seal it, and keep it at 180°C for 12 hours; after the autoclave is naturally cooled to room temperature, centrifuge and wash to collect the precipitate, and dry the product in an oven at 80°C for 12 hours to obtain a solid powder;

[0032] 9. The solid powder obtained in step 2 was calcined in air at 400°C for 2 hours at a heating rate of 2°C / min to obtain a MOF-In2O3-180 gas-sensitive material;

[0033] 4. Take 20 mg of the MOF-In2O3-180 gas-sensitive material obtained in step 3 and place it in an agate mortar. Add 2 drops of distilled water and grind it into a paste. Then evenly apply it on the outer surface of the ceramic tube to form a uniform gas-sensitive material film on the outer surface of the ceramic tube. The ceramic tube has been welded to the sensor base in advance. A nickel-chromium (Ni-Cr) heating wire that provides the appropriate operating temperature for the element passes through the ceramic tube and is also welded to the base.

[0034] 5. Let the gas-sensitive material film coated on the outer surface of the ceramic tube stand at room temperature for 1 day to dry naturally. After aging at 100mA for 24 hours, and then aging at 180mA for 24 hours, the gas sensor is prepared and the gas-sensing performance is tested.

Claims

1. A method for preparing a triethylamine gas sensor based on MOF-derived In2O3 gas-sensitive material, characterized in that The method comprises the following steps: (1) Dissolve 1.202 g of In(NO3)3·xH2O in 10–20 ml of N,N-dimethylformamide and stir for 5–10 minutes to prepare solution A. Dissolve 0.166 g of 1,4-benzenedicarboxylic acid in 10–20 ml of N,N-dimethylformamide and stir for 5–10 minutes to prepare solution B. (2) Solution A and Solution B are mixed and stirred for 10 to 20 minutes, and then transferred to a polytetrafluoroethylene-lined stainless steel autoclave, sealed, and maintained at 100 to 200° C. for 10 to 15 hours; the autoclave is naturally cooled to room temperature, and then centrifuged and washed to collect the precipitate, and the product is dried in an oven at 70 to 90° C. for 10 to 15 hours to obtain a solid powder; (3) calcining the solid powder obtained in step (2) in air at 390-420° C. for 1.0-3.0 hours at a heating rate of 1-4° C. / min to obtain a MOF-derived In2O3 gas-sensitive material; (4) Fabrication of MOF-derived In2O3 gas-sensitive material gas sensors; (5) Gas sensor gas sensitivity performance test.

2. The method for preparing a triethylamine gas sensor based on MOF-derived In2O3 gas-sensitive material according to claim 1, characterized in that: The reaction temperature in step (2) is 100-200° C., the reaction time is 10-15 hours; the calcination temperature is 390-420° C., the calcination time is 1.0-3.0 hours, and the heating rate is 1-4° C. / min.

3. The method for preparing a triethylamine gas sensor based on MOF-derived In2O3 gas-sensitive material according to claim 1, characterized in that: The gas sensor in step (4) is manufactured into a indirectly heated sintered element using a conventional method.

4. The method for preparing a triethylamine gas sensor based on MOF-derived In2O3 gas-sensitive material according to claim 1, characterized in that: The sensing test temperature in step (5) is 150°C.

Images