An acetone sensor based on MOF-derived oxygen-vacancy-rich α-Fe2O3 and its preparation method.

Abstract

This invention discloses an acetone sensor based on MOF-derived oxygen-vacancy-rich α-Fe₂O₃ and its fabrication method. The aforementioned acetone gas sensor has a planar structure, including an Al₂O₃ ceramic sheet, a pair of interdigitated gold electrodes printed on the upper surface of the Al₂O₃ ceramic sheet, a RuO₂ heating film printed on the lower surface of the Al₂O₃ ceramic sheet, a pair of strip-shaped gold electrodes printed on the surface of the RuO₂ heating film, a gas-sensitive film coated and fixed to the surface of the interdigitated gold electrodes, platinum wire leads I, II, III, and IV. The gas-sensitive film uses an oxygen-vacancy-rich α-Fe₂O₃ sensitive material. This invention can produce an acetone sensor with excellent acetone sensitivity characteristics, enabling efficient detection of low concentrations of acetone. It overcomes the problems of insufficient sensitivity and slow response speed of traditional gas sensors in acetone detection. Furthermore, the acetone sensor fabrication process is highly compatible with existing microfabrication technologies, meeting the needs of industrial production.

Description

Technical Field

[0001] This invention belongs to the field of gas sensor technology, specifically relating to an acetone sensor derived from metal-organic framework (MOF) and rich in oxygen-vacancy iron oxide (α-Fe2O3), and also relating to the preparation method and application of the acetone sensor. Background Technology

[0002] The detection of volatile organic compounds (VOCs) is of great significance in industrial safety and medical diagnostics. Acetone, a typical VOC, is both a widely used organic solvent and synthetic raw material in industrial production and an important biomarker for diabetes diagnosis. In industrial environments, acetone vapor concentrations exceeding 173 ppm can cause symptoms such as headaches and dizziness; higher concentrations can even be life-threatening. In the medical field, the concentration of acetone in human exhaled breath is closely related to blood glucose levels. The acetone concentration in the exhaled breath of healthy individuals is 0.3–0.9 ppm, while it can exceed 1.8 ppm in patients with type II diabetes. This makes acetone detection an important method for non-invasive diabetes screening.

[0003] Currently, acetone detection mainly relies on large analytical instruments such as gas chromatography and mass spectrometry. Although these instruments offer high accuracy, they suffer from limitations such as high equipment cost, complex operation, and difficulty in on-site detection. In contrast, metal-oxide-semiconductor (MOS) based gas sensors show promising application prospects in the field of VOCs detection due to their advantages of small size, low cost, and fast response. However, traditional MOS materials suffer from low sensitivity, high detection limits, and slow response speeds, failing to meet the requirements for real-time detection of trace amounts of acetone. Summary of the Invention

[0004] In view of the shortcomings of the prior art described above, the purpose of this invention is to provide an acetone sensor based on MOF-derived oxygen-vacancy-rich α-Fe2O3 and its preparation method.

[0005] An acetone gas sensor based on MOF-derived oxygen-vacancy-rich α-Fe₂O₃, comprising:

[0006] Al2O3 ceramic sheet, which serves as a substrate;

[0007] A pair of interdigitated gold electrodes are printed on the surface of the Al2O3 ceramic sheet;

[0008] RuO2 heating film, which is printed on the lower surface of the Al2O3 ceramic sheet;

[0009] A pair of gold bars, printed on the surface of the RuO2 heating film; and

[0010] A gas-sensitive thin film is coated and fixed on the surface of the interdigitated gold electrode.

[0011] As a further improvement to the above scheme, the acetone gas sensor has a planar structure; the acetone gas sensor also includes platinum wire lead I, platinum wire lead II, platinum wire lead III and platinum wire lead IV.

[0012] As a further improvement to the above scheme, platinum wire lead I and platinum wire lead II are respectively fixedly connected to two interdigitated gold electrodes, and platinum wire lead III and platinum wire lead IV are respectively fixedly connected to two strip gold electrodes.

[0013] As a further improvement to the above scheme, the gas-sensitive film adopts an α-Fe2O3 sensitive material rich in oxygen vacancies. The specific steps of the preparation method of the α-Fe2O3 sensitive material rich in oxygen vacancies are as follows: ferric chloride hexahydrate, terephthalic acid and histidine are dissolved in N,N-dimethylformamide and stirred at room temperature. The resulting mixed solution is transferred to a hydrothermal reactor with a polytetrafluoroethylene liner for hydrothermal reaction. After cooling to room temperature, the precipitate is washed with deionized water and ethanol by alternating centrifugation and drying to obtain a defective MIL-101(Fe) precursor powder. The precursor powder is calcined to obtain the α-Fe2O3 sensitive material rich in oxygen vacancies. This invention modulates the synthesis conditions of the MIL-101(Fe) precursor and combines it with calcination to successfully prepare an α-Fe2O3 functional material rich in oxygen vacancies. By introducing oxygen vacancy defects, abundant chemically adsorbed oxygen species are formed on the surface of the prepared α-Fe2O3 sensitive material. These active sites effectively promote the chemical adsorption of acetone molecules and surface reaction kinetics, significantly enhancing the material's sensitivity performance, thereby improving the sensitivity to target gas capture.

[0014] As a further improvement to the above scheme, the mass ratio of ferric chloride hexahydrate, terephthalic acid and histidine is 0.6-1.8:0.2-0.6:0-0.12, and the amount of N,N-dimethylformamide used is equivalent to 5-38 times the total amount of ferric chloride hexahydrate, terephthalic acid and histidine.

[0015] As a further improvement to the above scheme, the hydrothermal reaction temperature is 120–180℃, and the reaction time is 12–24 h; the calcination treatment conditions are: heating to 400–500℃ at a heating rate of 2℃ / min and holding for 2–4 h. This invention, through the controllability of reaction temperature, time, and precursor ratio, achieves the controllable preparation of surface defect structures in α-Fe₂O₃ sensitive materials, which is beneficial for optimizing material properties.

[0016] A method for preparing the acetone gas sensor includes the following steps:

[0017] (1) A pair of interdigitated gold electrodes were printed on the upper surface of an Al2O3 ceramic sheet using screen printing, a RuO2 heating film was laid flat on the lower surface of the Al2O3 ceramic sheet, and a pair of strip gold electrodes were printed on the surface of the RuO2 heating film to obtain the sensor substrate.

[0018] (2) The sensor substrate obtained in step (1) is cleaned and dried;

[0019] (3) Disperse the oxygen-vacancy-rich α-Fe2O3 sensitive material in water, mix it evenly to obtain a dispersion, use a micropipette to accurately drop the dispersion onto the gold electrode area of ​​the sensor substrate after step (2), and then perform low-temperature heat treatment under infrared lamp for 1 to 3 hours to obtain a gas sensitive film.

[0020] (4) After aging at 350-400℃ for 24-72h, four platinum wire leads are installed in sequence to obtain the acetone sensor.

[0021] As a further improvement to the above scheme, in step (1), the Al2O3 ceramic sheet has a length of 1.5-3 mm, a width of 1.5-3 mm, and a thickness of 0.25-0.5 mm; the interdigitated gold electrode has a width of 200-300 μm and a thickness of 10-30 μm; the RuO2 heating film has a thickness of 20-30 μm; and the strip gold electrode has a thickness of 10-30 μm.

[0022] As a further improvement to the above scheme, in step (2), the sensor substrate is ultrasonically cleaned with anhydrous ethanol and deionized water in sequence, and then dried at 60-80°C.

[0023] As a further improvement to the above scheme, in step (3), the concentration of the dispersion is 50-100 mg / mL, and the thickness of the gas-sensitive film is 20-100 μm.

[0024] An application of the aforementioned acetone gas sensor in acetone detection.

[0025] Compared with the prior art, the beneficial effects of the present invention are:

[0026] This invention is highly compatible with existing microfabrication technologies, possesses excellent process repeatability and scalable production potential, and can meet the needs of industrial production. The resulting acetone sensor is small in size and has excellent sensing characteristics: high sensitivity, with a response value of up to 98 for 100ppm acetone; a detection limit as low as 1ppm, and rapid response with a response time of 2s; and no performance degradation after 20 tests, exhibiting good repeatability.

[0027] This invention can produce an acetone sensor with excellent acetone sensitivity, which can achieve efficient detection of low concentrations of acetone. It overcomes the problems of insufficient sensitivity and slow response speed of traditional gas sensors in acetone detection. The acetone sensor is compatible with existing microfabrication technology during fabrication and can meet the needs of industrial production.

[0028] This invention develops a simple and controllable oxygen vacancy regulation strategy, which can construct high-performance MOF-derived MOS materials with abundant oxygen vacancies, enabling acetone sensing with high sensitivity, low detection limit and fast response, which is of great significance for industrial safety monitoring and medical diagnosis. Attached Figure Description

[0029] Figure 1 The diagram shown is a structural schematic of the acetone sensor provided by the present invention.

[0030] Figure 2 The image shows the X-ray diffraction pattern of the α-Fe2O3 sensitive material prepared in Example 1.

[0031] Figure 3 The image shown is a scanning electron microscope image of the α-Fe2O3 sensitive material prepared in Example 1.

[0032] Figure 4 The image shows the O1s X-ray photoelectron spectrum of the α-Fe2O3 sensitive material prepared in Example 1.

[0033] Figure 5 The figure shows the oxygen temperature-programmed desorption curve of the α-Fe2O3 sensitive material prepared in Example 1.

[0034] Figure 6 The figure shows the dynamic resistance response curve of the acetone sensor based on α-Fe2O3 sensitive material in Example 1 to 100 ppm acetone at an operating temperature of 260°C.

[0035] Figure 7 The figure shows the repeatability test curve of the acetone sensor based on α-Fe2O3 sensitive material in Example 1 for 20ppm acetone at an operating temperature of 260℃.

[0036] Figure 8 The figure shows the response recovery curve of the acetone sensor based on α-Fe2O3 sensitive material in Example 1 to 20ppm acetone at an operating temperature of 260℃.

[0037] Figure 9 The figure shows the response recovery curve of the acetone sensor based on α-Fe2O3 sensitive material in Example 2 to 20ppm acetone at an operating temperature of 300℃.

[0038] Explanation of main component symbols

[0039] 1. Al2O3 ceramic sheet; 2. Interdigitated gold electrode; 3. RuO2 heating film; 4. Strip gold electrode; 5. Gas-sensitive film; 6. Platinum wire lead I; 7. Platinum wire lead II; 8. Platinum wire lead III; 9. Platinum wire lead IV.

[0040] The above description of the main component symbols, together with the accompanying drawings and specific embodiments, provides a more detailed explanation of the present invention. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. Additional aspects and advantages of this invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. It should be understood that the following description is merely illustrative and not intended to limit the invention.

[0042] The specific embodiments of the present invention will be described in detail below.

[0043] Example 1

[0044] Please see Figure 1 This embodiment provides an acetone gas sensor based on MOF-derived oxygen-vacancy-rich α-Fe2O3, which has a planar structure. The acetone gas sensor includes an Al2O3 ceramic sheet 1 as a substrate, a pair of interdigitated gold electrodes 2 printed on the upper surface of the Al2O3 ceramic sheet 1, a RuO2 heating film 3 printed on the lower surface of the Al2O3 ceramic sheet 1, a pair of strip gold electrodes 4 printed on the surface of the RuO2 heating film 3, a gas-sensitive film 5 coated and fixed on the surface of the interdigitated gold electrodes 2, platinum wire leads I6 and II7 respectively fixedly connected to the two interdigitated gold electrodes 2, and platinum wire leads III8 and IV9 respectively fixedly connected to the two strip gold electrodes 4.

[0045] The gas-sensitive film 5 in this embodiment uses an α-Fe₂O₃ sensitive material rich in oxygen vacancies. The specific steps for preparing the α-Fe₂O₃ sensitive material rich in oxygen vacancies are as follows: 0.6 g of ferric chloride hexahydrate (FeCl₃·6H₂O), 0.2 g of terephthalic acid, and 0.06 g of histidine are dissolved in 15 mL of N,N-dimethylformamide (DMF) and stirred at room temperature for 0.5 h to obtain a homogeneous mixed solution. The mixed solution is transferred to a hydrothermal reactor with a polytetrafluoroethylene liner and reacted at 120 °C for 12 h. After cooling to room temperature, the precipitate is washed with deionized water and ethanol by alternating centrifugation and drying to obtain defective MIL-101(Fe) precursor powder. The precursor powder is placed in a tube furnace and heated to 400 °C at a heating rate of 2 °C / min and held for 2 h to obtain the α-Fe₂O₃ sensitive material rich in oxygen vacancies.

[0046] The strip gold electrode 4 functions as a heating electrode. In this embodiment, the acetone gas sensor operates as follows: During operation, a working voltage is applied across the strip gold electrode 4 to bring the sensor to its optimal operating temperature. When the gas-sensitive thin film 5 comes into contact with the target gas, the oxygen adsorbed on its surface reacts with the target gas molecules, causing a change in the film's resistance. The target gas is detected by monitoring the resistance change across the interdigitated electrodes. The response (S) of this embodiment's acetone gas sensor is defined as: S = R a / R g , where R a and R g These are the resistance values ​​of the acetone sensor against an air background and in the atmosphere to be measured, respectively.

[0047] The preparation method of the acetone sensor in this embodiment includes the following steps:

[0048] (1) A pair of interdigitated gold electrodes 2 with a width of 200 μm and a thickness of 10 μm were printed on the upper surface of an Al2O3 ceramic sheet 1 with a length of 1.5 mm, a width of 1.5 mm and a thickness of 0.25 mm using screen printing. A RuO2 heating film 3 with a thickness of 20 μm was laid and printed on the lower surface of the Al2O3 ceramic sheet 1. A pair of strip gold electrodes 4 with a thickness of 10 μm were printed on the surface of the RuO2 heating film 3 to obtain the sensor substrate.

[0049] (2) The sensor substrate obtained in step (1) was ultrasonically cleaned with anhydrous ethanol and deionized water in sequence, and then dried at 60°C.

[0050] (3) Disperse the oxygen-vacancy-rich α-Fe2O3 sensitive material in water and mix it evenly to obtain a dispersion with a concentration of 50 mg / mL. Use a micropipette to accurately drop the dispersion onto the gold electrode area of ​​the sensor substrate after step (2). Then perform low-temperature heat treatment under infrared lamp for 1 hour to obtain a gas sensitive film 5 with a thickness of 20 μm.

[0051] (4) After aging at 350℃ for 24 hours, four platinum wire leads are installed in sequence to obtain the acetone sensor.

[0052] Example 2

[0053] This embodiment provides an acetone gas sensor based on MOF-derived oxygen-vacancy-rich α-Fe2O3, which has the same structure as in Embodiment 1. The difference lies in the preparation of the acetone gas sensor and the preparation of the oxygen-vacancy-rich α-Fe2O3 sensitive material used in this embodiment.

[0054] The preparation method of the oxygen-vacancy-rich α-Fe2O3 sensitive material in this embodiment is as follows: 0.6 g of ferric chloride hexahydrate (FeCl3·6H2O), 0.2 g of terephthalic acid and 0.09 g of histidine are dissolved in 30 mL of N,N-dimethylformamide (DMF) and stirred at room temperature for 0.5 h to obtain a homogeneous mixed solution. The mixed solution is transferred to a hydrothermal reactor with a polytetrafluoroethylene liner and reacted at 120 °C for 24 h. After cooling to room temperature, the precipitate is washed with deionized water and ethanol by alternating centrifugation and drying to obtain defective MIL-101(Fe) precursor powder. The precursor powder is placed in a tube furnace and heated to 400 °C at a heating rate of 2 °C / min and held for 4 h to obtain the oxygen-vacancy-rich α-Fe2O3 sensitive material.

[0055] The preparation method of the acetone sensor in this embodiment includes the following steps:

[0056] (1) A pair of interdigitated gold electrodes 2 with a width of 200 μm and a thickness of 10 μm were printed on the upper surface of an Al2O3 ceramic sheet 1 with a length of 3 mm, a width of 3 mm and a thickness of 0.5 mm using screen printing. A RuO2 heating film 3 with a thickness of 20 μm was laid and printed on the lower surface of the Al2O3 ceramic sheet 1. A pair of strip gold electrodes 4 with a thickness of 10 μm were printed on the surface of the RuO2 heating film 3 to obtain the sensor substrate.

[0057] (2) The sensor substrate obtained in step (1) was ultrasonically cleaned with anhydrous ethanol and deionized water in sequence, and then dried at 80°C.

[0058] (3) Disperse the oxygen-vacancy-rich α-Fe2O3 sensitive material in water and mix it evenly to obtain a dispersion with a concentration of 50 mg / mL. Use a micropipette to accurately drop the dispersion onto the gold electrode area of ​​the sensor substrate after step (2). Then perform low-temperature heat treatment under infrared lamp for 1 hour to obtain a gas sensitive film 5 with a thickness of 20 μm.

[0059] (4) After aging at 350℃ for 24 hours, four platinum wire leads are installed in sequence to obtain the acetone sensor.

[0060] Example 3

[0061] This embodiment provides an acetone gas sensor based on MOF-derived oxygen-vacancy-rich α-Fe2O3, which has the same structure as in Embodiment 1. The difference lies in the preparation of the acetone gas sensor and the preparation of the oxygen-vacancy-rich α-Fe2O3 sensitive material used in this embodiment.

[0062] The preparation method of the oxygen-vacancy-rich α-Fe2O3 sensitive material in this embodiment is as follows: 1.2 g of ferric chloride hexahydrate (FeCl3·6H2O), 0.4 g of terephthalic acid, and 0.12 g of histidine are dissolved in 15 mL of N,N-dimethylformamide (DMF). The mixture is stirred at room temperature for 1 h to obtain a homogeneous solution. The solution is then transferred to a hydrothermal reactor with a polytetrafluoroethylene liner and reacted at 150 °C for 12 h. After cooling to room temperature, the precipitate is washed with deionized water and ethanol by alternating centrifugation. The precipitate is dried to obtain defective MIL-101(Fe) precursor powder. The precursor powder is placed in a tube furnace and heated to 400 °C at a heating rate of 2 °C / min, and held for 3 h to obtain the oxygen-vacancy-rich α-Fe2O3 sensitive material.

[0063] The preparation method of the acetone sensor in this embodiment includes the following steps:

[0064] (1) A pair of interdigitated gold electrodes 2 with a width of 300 μm and a thickness of 20 μm were printed on the upper surface of an Al2O3 ceramic sheet 1 with a length of 1.5 mm, a width of 1.5 mm and a thickness of 0.5 mm using screen printing. A RuO2 heating film 3 with a thickness of 30 μm was laid and printed on the lower surface of the Al2O3 ceramic sheet 1. A pair of strip gold electrodes 4 with a thickness of 20 μm were printed on the surface of the RuO2 heating film 3 to obtain the sensor substrate.

[0065] (2) Same as Example 1;

[0066] (3) Disperse the oxygen-vacancy-rich α-Fe2O3 sensitive material in water and mix it evenly to obtain a dispersion with a concentration of 100 mg / mL. Use a micropipette to accurately drop the dispersion onto the gold electrode area of ​​the sensor substrate after step (2). Then perform low-temperature heat treatment under infrared lamp for 2 hours to obtain a gas sensitive film 5 with a thickness of 60 μm.

[0067] (4) After aging at 350℃ for 48 hours, four platinum wire leads are installed in sequence to obtain the acetone sensor.

[0068] Example 4

[0069] This embodiment provides an acetone gas sensor based on MOF-derived oxygen-vacancy-rich α-Fe2O3, which has the same structure as in Embodiment 1. The difference lies in the preparation of the acetone gas sensor and the preparation of the oxygen-vacancy-rich α-Fe2O3 sensitive material used in this embodiment.

[0070] The preparation method of the oxygen-vacancy-rich α-Fe2O3 sensitive material in this embodiment is as follows: 1.2 g of ferric chloride hexahydrate (FeCl3·6H2O), 0.6 g of terephthalic acid, and 0.12 g of histidine are dissolved in 30 mL of N,N-dimethylformamide (DMF). The mixture is stirred at room temperature for 2 h to obtain a homogeneous solution. The solution is then transferred to a hydrothermal reactor with a polytetrafluoroethylene liner and reacted at 180 °C for 24 h. After cooling to room temperature, the precipitate is washed with deionized water and ethanol by alternating centrifugation. The precipitate is dried to obtain defective MIL-101(Fe) precursor powder. The precursor powder is placed in a tube furnace and heated to 500 °C at a heating rate of 2 °C / min, and held for 4 h to obtain the oxygen-vacancy-rich α-Fe2O3 sensitive material.

[0071] The preparation method of the acetone sensor in this embodiment includes the following steps:

[0072] (1) A pair of interdigitated gold electrodes 2 with a width of 200 μm and a thickness of 30 μm were printed on the upper surface of an Al2O3 ceramic sheet 1 with a length of 1.5 mm, a width of 1.5 mm and a thickness of 0.25 mm using screen printing. A RuO2 heating film 3 with a thickness of 30 μm was laid and printed on the lower surface of the Al2O3 ceramic sheet 1. A pair of strip gold electrodes 4 with a thickness of 30 μm were printed on the surface of the RuO2 heating film 3 to obtain the sensor substrate.

[0073] (2) The sensor substrate obtained in step (1) was ultrasonically cleaned with anhydrous ethanol and deionized water in sequence, and then dried at 80°C.

[0074] (3) Disperse the oxygen-vacancy-rich α-Fe2O3 sensitive material in water and mix it evenly to obtain a dispersion with a concentration of 100 mg / mL. Use a micropipette to accurately drop the dispersion onto the gold electrode area of ​​the sensor substrate after step (2). Then perform low-temperature heat treatment for 3 hours under an infrared lamp to obtain a gas sensitive film 5 with a thickness of 100 μm.

[0075] (4) After aging at 400℃ for 72 hours, four platinum wire leads are installed in sequence to obtain the acetone sensor.

[0076] Example 5

[0077] This embodiment provides an acetone gas sensor based on MOF-derived oxygen-vacancy-rich α-Fe2O3, which has the same structure as in Embodiment 1. The difference lies in the preparation of the acetone gas sensor and the preparation of the oxygen-vacancy-rich α-Fe2O3 sensitive material used in this embodiment.

[0078] The preparation method of the oxygen-vacancy-rich α-Fe2O3 sensitive material in this embodiment is as follows: 1.8 g of ferric chloride hexahydrate (FeCl3·6H2O), 0.6 g of terephthalic acid, and 0 g of histidine are dissolved in 30 mL of N,N-dimethylformamide (DMF). The mixture is stirred at room temperature for 1 h to obtain a homogeneous solution. The solution is then transferred to a hydrothermal reactor with a polytetrafluoroethylene liner and reacted at 120 °C for 24 h. After cooling to room temperature, the precipitate is washed with deionized water and ethanol by alternating centrifugation. The precipitate is dried to obtain defective MIL-101(Fe) precursor powder. The precursor powder is placed in a tube furnace and heated to 500 °C at a heating rate of 2 °C / min, and held for 3 h to obtain the oxygen-vacancy-rich α-Fe2O3 sensitive material.

[0079] The preparation method of the acetone sensor in this embodiment includes the following steps:

[0080] (1) A pair of interdigitated gold electrodes 2 with a width of 200 μm and a thickness of 20 μm were printed on the upper surface of an Al2O3 ceramic sheet 1 with a length of 3 mm, a width of 3 mm and a thickness of 0.25 mm using screen printing. A RuO2 heating film 3 with a thickness of 30 μm was laid and printed on the lower surface of the Al2O3 ceramic sheet 1. A pair of strip gold electrodes 4 with a thickness of 30 μm were printed on the surface of the RuO2 heating film 3 to obtain the sensor substrate.

[0081] (2) The sensor substrate obtained in step (1) was ultrasonically cleaned with anhydrous ethanol and deionized water in sequence, and then dried at 80°C.

[0082] (3) Same as Example 1;

[0083] (4) Same as Example 1.

[0084] Example 6

[0085] This embodiment provides an acetone gas sensor based on MOF-derived oxygen-vacancy-rich α-Fe2O3, which has the same structure as in Embodiment 1. The difference lies in the preparation of the acetone gas sensor and the preparation of the oxygen-vacancy-rich α-Fe2O3 sensitive material used in this embodiment.

[0086] The preparation method of the oxygen-vacancy-rich α-Fe2O3 sensitive material in this embodiment is as follows: 0.6 g of ferric chloride hexahydrate (FeCl3·6H2O), 0.6 g of terephthalic acid and 0.06 g of histidine are dissolved in 30 mL of N,N-dimethylformamide (DMF) and stirred at room temperature for 2 h to obtain a homogeneous mixed solution. The mixed solution is transferred to a hydrothermal reactor with a polytetrafluoroethylene liner and reacted at 180 °C for 12 h. After cooling to room temperature, the precipitate is washed with deionized water and ethanol by alternating centrifugation and drying to obtain defective MIL-101(Fe) precursor powder. The precursor powder is placed in a tube furnace and heated to 500 °C at a heating rate of 2 °C / min and held for 4 h to obtain the oxygen-vacancy-rich α-Fe2O3 sensitive material.

[0087] The preparation method of the acetone sensor in this embodiment includes the following steps:

[0088] (1) A pair of interdigitated gold electrodes 2 with a width of 300 μm and a thickness of 30 μm were printed on the upper surface of an Al2O3 ceramic sheet 1 with a length of 1.5 mm, a width of 1.5 mm and a thickness of 0.25 mm using screen printing. A RuO2 heating film 3 with a thickness of 30 μm was laid and printed on the lower surface of the Al2O3 ceramic sheet 1. A pair of strip gold electrodes 4 with a thickness of 30 μm were printed on the surface of the RuO2 heating film 3 to obtain the sensor substrate.

[0089] (2) The sensor substrate obtained in step (1) was ultrasonically cleaned with anhydrous ethanol and deionized water in sequence, and then dried at 80°C.

[0090] (3) Same as Example 1;

[0091] (4) After aging at 400℃ for 24 hours, four platinum wire leads are installed in sequence to obtain the acetone sensor.

[0092] Figure 2 The image shows the X-ray diffraction pattern of the α-Fe2O3 sensitive material prepared in Example 1. Analysis... Figure 2It can be seen that a series of diffraction peaks appearing at 2θ of 24.07°, 32.99°, 35.66°, 49.46°, 53.97°, 62.65° and 63.95° correspond to the (012), (104), (110), (024), (116), (214) and (300) crystal planes of α-Fe2O3 crystal (JCPDS No. 33-0664). All diffraction peaks match well with the standard card and no impurity phase was detected. This proves that the present invention has successfully prepared high-purity α-Fe2O3 sensitive material.

[0093] Figure 3 The image shown is a scanning electron microscope image of the α-Fe2O3 sensitive material prepared in Example 1. Analysis Figure 3 It is known that the α-Fe2O3 sensitive material is composed of uniformly distributed nanoparticles with a particle size range of 50 to 200 nm. This indicates that the α-Fe2O3 sensitive material prepared in this invention has a nanostructure with a high specific surface area, which can provide abundant surface active sites for gas molecules and significantly enhance the gas adsorption capacity and surface reactivity of the material.

[0094] Figure 4 The image shows the O1s X-ray photoelectron spectrum of the α-Fe2O3 sensitive material prepared in Example 1. Analysis... Figure 4 The O 1s spectrum can be deconvolved into three characteristic peaks: 529.6 eV (lattice oxygen), 531.0 eV (oxygen vacancy), and 532.9 eV (chemisorbed oxygen). This indicates that the α-Fe2O3 sensitive material prepared in this invention has a rich surface defect structure, which is beneficial to improving the material's electron transport performance and gas sensitivity characteristics.

[0095] Figure 5 The figure shows the oxygen temperature-programmed desorption curve of the α-Fe2O3 sensitive material prepared in Example 1. Analysis Figure 5 It can be seen that the surface of the α-Fe2O3 sensitive material contains abundant chemically adsorbed oxygen (O2). - O - and O 2- This confirms that the α-Fe2O3 sensitive surface prepared by this invention contains multiple types of active oxygen species, which originate from oxygen vacancy defects on the α-Fe2O3 surface. These chemically adsorbed oxygens can significantly promote the surface oxidation reaction of acetone gas.

[0096] Figure 6 The figure shows the dynamic resistance response curves of the acetone sensor based on α-Fe2O3 sensing material in Example 1 at an operating temperature of 260°C for 1–100 ppm acetone. Analysis is provided. Figure 6It can be seen that after exposure to acetone, the resistance of the sensor decreases rapidly, and when the gas is switched to air, the resistance quickly returns to the initial state. The prepared α-Fe2O3-based acetone sensor can detect acetone gas as low as 1 ppm, and the sensor response gradually increases with the increase of acetone concentration.

[0097] Figure 7 The figure shows the repeatability test curve of the acetone sensor based on α-Fe2O3 sensing material in Example 1 at an operating temperature of 260°C for 20 ppm acetone. Analysis... Figure 7 It can be seen that after the sensor was repeatedly exposed to a 20ppm acetone atmosphere 20 times, the response remained almost unchanged. This proves that the sensor of the present invention has good response repeatability, and this excellent repeatability is due to the structural stability of the α-Fe2O3 sensitive material and the reversible surface reaction mechanism.

[0098] Figure 8 The figure shows the response recovery curve of the acetone sensor based on α-Fe2O3 sensing material in Example 1 to 20 ppm acetone at an operating temperature of 260°C. Analysis... Figure 8 It is known that the sensor of the present invention has good response recovery characteristics to acetone and a fast response recovery rate. Figure 9 The figure shows the response recovery curve of the acetone sensor based on α-Fe2O3 sensing material in Example 2 to 20ppm acetone at an operating temperature of 300℃. Analysis... Figure 9 It is known that the sensor of the present invention has good response recovery characteristics to acetone and a fast response recovery rate.

[0099] The above test results prove that the present invention can produce an acetone sensor with excellent acetone sensitivity characteristics, which can achieve efficient detection of low concentrations of acetone and overcome the problems of insufficient sensitivity and slow response speed of traditional gas sensors in acetone detection.

[0100] The above embodiments are merely preferred embodiments of the present invention. Any simple modifications, alterations, and substitutions made to the above embodiments based on the technical essence of the present invention shall fall within the scope of the technical solution of the present invention.

Claims

1. An acetone gas sensor based on MOF-derived oxygen-vacancy-rich α-Fe₂O₃, characterized in that, include: Al2O3 ceramic sheet, which serves as a substrate; A pair of interdigitated gold electrodes are printed on the surface of the Al2O3 ceramic sheet; RuO2 heating film, which is printed on the lower surface of the Al2O3 ceramic sheet; A pair of gold bars are printed on the surface of the RuO2 heating film; as well as A gas-sensitive thin film is coated and fixed on the surface of the interdigitated gold electrode; The gas-sensitive film uses an α-Fe2O3 sensitive material rich in oxygen vacancies. The preparation method of the α-Fe2O3 sensitive material rich in oxygen vacancies is as follows: ferric chloride hexahydrate, terephthalic acid and histidine are dissolved in N,N-dimethylformamide and stirred at room temperature. The resulting mixed solution is transferred to a hydrothermal reactor with a polytetrafluoroethylene liner for hydrothermal reaction. After cooling to room temperature, the precipitate is washed with deionized water and ethanol by alternating centrifugation and drying to obtain a defective MIL-101(Fe) precursor powder. The precursor powder is calcined to obtain the α-Fe2O3 sensitive material rich in oxygen vacancies. The hydrothermal reaction temperature is 120~180℃. o C, the reaction time is 12~24h; the calcination treatment conditions are: at 2 o The heating rate was increased to 400~500 °C / min. o C, keep for 2~4 hours.

2. The acetone gas sensor according to claim 1, characterized in that, The acetone gas sensor has a planar structure; the acetone gas sensor also includes platinum wire lead I, platinum wire lead II, platinum wire lead III and platinum wire lead IV.

3. The acetone gas sensor according to claim 2, characterized in that, Platinum wire lead I and platinum wire lead II are respectively fixedly connected to two interdigitated gold electrodes, and platinum wire lead III and platinum wire lead IV are respectively fixedly connected to two strip gold electrodes.

4. The acetone gas sensor according to claim 1, characterized in that, The mass ratio of ferric chloride hexahydrate, terephthalic acid, and histidine is 0.6~1.8:0.2~0.6:0~0.12, and the amount of N,N-dimethylformamide used is equivalent to 5~38 times the total amount of ferric chloride hexahydrate, terephthalic acid, and histidine.

5. A method for preparing an acetone gas sensor as described in any one of claims 1 to 4, characterized in that, Includes the following steps: (1) A pair of interdigitated gold electrodes were printed on the upper surface of an Al2O3 ceramic sheet using screen printing, a RuO2 heating film was laid flat on the lower surface of the Al2O3 ceramic sheet, and a pair of strip gold electrodes were printed on the surface of the RuO2 heating film to obtain the sensor substrate. (2) The sensor substrate obtained in step (1) is cleaned and dried; (3) Disperse the oxygen-vacancy-rich α-Fe2O3 sensitive material in water, mix it evenly to obtain a dispersion, use a micropipette to accurately drop the dispersion onto the gold electrode area of ​​the sensor substrate after step (2), and then perform low-temperature heat treatment under infrared lamp for 1~3 hours to obtain a gas sensitive film. (4) After aging at 350~400℃ for 24~72h, four platinum wire leads are installed in sequence to obtain the acetone sensor.

6. The preparation method according to claim 5, characterized in that, In step (1), the Al2O3 ceramic sheet has a length of 1.5~3mm, a width of 1.5~3mm, and a thickness of 0.25~0.5mm; the interdigitated gold electrode has a width of 200~300μm and a thickness of 10~30μm; the RuO2 heating film has a thickness of 20~30μm; and the strip gold electrode has a thickness of 10~30μm.

7. The preparation method according to claim 6, characterized in that, In step (2), the sensor substrate is ultrasonically cleaned with anhydrous ethanol and deionized water in sequence, and then dried at 60~80℃. In step (3), the concentration of the dispersion is 50~100mg / mL, and the thickness of the gas-sensitive film is 20~100μm.

8. The application of an acetone gas sensor as described in any one of claims 1 to 4 in acetone detection.

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