Noble metal@COFs@MOS@carbon hollow nanosphere composite thin films, sensors and their preparation methods

Abstract

This invention discloses a noble metal@COFs@MOS@carbon hollow nanosphere composite film, a sensor, and its preparation method. The composite film uses carbon hollow nanospheres as a substrate, on which metal oxide semiconductor quantum grains, covalent organic compounds (COFs), and noble metals are sequentially loaded. The sensor uses a sensor device as a substrate, with the noble metal@COFs@MOS@carbon hollow nanosphere composite film deposited on the substrate surface for detecting methylheptenone gas. This invention's noble metal@COFs@MOS@carbon hollow nanosphere composite film can be used as a sensitive layer in a methylheptenone gas sensor. This composite film has a low operating temperature, high gas sensitivity, high selectivity for methylheptenone, good repeatability, good stability, low cost, simple preparation method, and can be mass-produced.

Description

Technical Field

[0001] This invention relates to the field of sensor technology, specifically to a noble metal@COFs@MOS@carbon hollow nanosphere composite thin film, a sensor, and a method for preparing the same. Background Technology

[0002] Gastric cancer is often diagnosed at an insidious stage, leading to delayed or ineffective treatment. Current diagnostic methods for gastric cancer suffer from technical problems such as complex procedures, high detection limits, interference, and inaccurate results. Therefore, finding an effective and widely applicable screening technology for regular screening of high-risk groups has become an urgent clinical need. To address these issues, multimodal sensor arrays are combined with pattern recognition technology, along with nanotechnology to solve stability and accuracy problems. The use of various forms of nanomaterials not only improves their sensing performance for cancer markers but also promotes the rapid development of smart healthcare, paving the way for medical advancements. In recent years, exhaled breath analysis has provided an innovative, non-invasive method for diagnosing gastric cancer. This method is characterized by its ease of operation and high patient compliance. Currently, Professor Haik's team in Israel has discovered that exhaled breath can diagnose 17 types of cancer by identifying cancer-related specific exhaled VOCs tumor markers. This study employed a nanosensor method to detect exhaled breath samples from gastric cancer patients and established a predictive model using machine learning algorithms. Analysis revealed that 6-methyl-5-hepten-2-one (MHH) was significantly elevated in gastric cancer patients, suggesting its potential as a biomarker for gastric cancer. However, the sensing materials used in breath detection sensors suffer from drawbacks such as poor moisture resistance, baseline drift, and high energy consumption. Therefore, there is an urgent need to develop novel breath sensors with low power consumption, strong moisture resistance, and excellent stability. Summary of the Invention

[0003] Purpose of the invention: In order to solve the technical problems existing in the prior art, the present invention aims to provide a noble metal@COFs@MOS@carbon hollow nanosphere composite film with high detection sensitivity, high selectivity and convenient operation. The present invention also provides a sensor based on the composite film and its preparation method.

[0004] Technical solution: The noble metal@COFs@MOS@carbon hollow nanosphere composite film of the present invention uses carbon hollow nanospheres as a substrate, and metal oxide semiconductor (MOS) quantum grains, covalent organic compounds COFs and noble metals are sequentially loaded on the substrate.

[0005] Furthermore, the molar proportions of carbon hollow nanospheres, metal oxide semiconductor quantum grains, covalent organic compounds (COFs), and noble metals in the composite film are 18-27%, 33-40%, 27-36%, and 3-6%, respectively. The composite film includes composite hollow nanospheres, with carbon hollow nanospheres as the inner layer, metal oxide semiconductor quantum grains as the middle layer, and covalent organic compounds (COFs) as the outermost layer. The average diameter of the composite hollow nanospheres is 700-800 nm, and the average wall thickness is 200-300 nm. The average diameter of the carbon hollow nanospheres is 100-150 nm. The average particle size of the metal oxide semiconductor quantum dot grains is 3-5 nm, and the average thickness of the film layer formed by the covalent organic compounds (COFs) is 80-120 nm.

[0006] The sensor based on the noble metal@COFs@MOS@carbon hollow nanosphere composite film of the present invention uses a sensor device as a substrate, and deposits the noble metal@COFs@MOS@carbon hollow nanosphere composite film on the surface of the substrate.

[0007] Furthermore, the sensor is used to detect methyl heptenone gas, and the thickness of the noble metal@COFs@MOS@carbon hollow nanosphere composite film is 700-800 nm.

[0008] The method for fabricating a sensor based on a noble metal@COFs@MOS@carbon hollow nanosphere composite film according to the present invention includes the following steps:

[0009] (1) Carbon hollow nanospheres are prepared on the surface of the sensor device to obtain a sensor device loaded with a carbon hollow nanosphere film;

[0010] (2) The sensor device loaded with carbon hollow nanosphere film is immersed in the metal oxide semiconductor MOS precursor solution for dip coating, taken out and dried and placed in a sealed environment for water vapor-assisted crystallization treatment. After treatment, glow discharge treatment is performed to obtain the sensor device loaded with MOS@carbon hollow nanosphere composite film.

[0011] (3) In a protective gas, the sensor device loaded with MOS@carbon hollow nanosphere composite film is immersed in a covalent organic compound COFs precursor solution for dip coating, and after drying, it is subjected to organic solvent vapor-assisted crystallization treatment to obtain the sensor device loaded with COFs@MOS@carbon hollow nanosphere composite film.

[0012] (4) In a protective gas, the sensor device loaded with COFs@MOS@carbon hollow nanosphere composite film is immersed in a mixture of noble metal salts for dip coating. After drying, it is placed in organic solvent vapor for thermal evaporation treatment. After treatment, glow discharge treatment is performed to obtain the sensor based on noble metal@COFs@MOS@carbon hollow nanosphere composite film.

[0013] Further, in step (1), the step of preparing carbon hollow nanospheres on the surface of the sensor device is as follows: under a protective gas, the concentrated solution of carbon hollow nanosphere precursor is dipped onto the sensor device, freeze-dried and collected, and then carbonized in an inert gas to obtain the product; the preparation method of the concentrated solution of carbon hollow nanosphere precursor is as follows: under high stirring speed, water, ammonia, formaldehyde and 3-aminophenol are mixed, acetone is added, oligomers are removed, and the resulting mixed solution is rotary evaporated to obtain the product; the volume percentages of water, ammonia, formaldehyde and 3-aminophenol are 90-95%, 4-8%, 1-3% and 1-3%, respectively, and the volume of acetone is 3-5 times the total volume of water, ammonia and formaldehyde; the carbonization conditions are: carbonization at 750-850℃ for 2-4 hours.

[0014] Further, in step (2), the preparation method of the metal oxide semiconductor (MOS) precursor solution is as follows: dissolve the metal oxide semiconductor precursor in an organic solvent, add a surfactant and mix evenly to obtain a precursor sol solution. Then, add hydrochloric acid to the precursor solution and disperse it by ultrasonication to obtain the metal oxide semiconductor precursor solution. The metal oxide semiconductor precursor is indium trichloride, zinc dichloride or titanium tetrachloride, the organic solvent is anhydrous ethanol, anhydrous isopropanol or anhydrous butanol, the mass ratio of the metal oxide semiconductor precursor to the volume ratio of the organic solvent is 1.0-2.0g:5-10ml, and the surfactant is P123, F127 or Brij35, preferably F127.

[0015] Further, in step (3), the preparation method of the covalent organic compound COFs precursor solution is as follows: in a protective gas, terephthalaldehyde and tetra(4-aminophenyl)methane are dissolved in anhydrous dioxane to obtain a mixed solution; under ultrasonic assistance, an aqueous acetic acid solution is added to the mixed solution, ultrasonically treated, and then vacuum treated to obtain the solution; the molar ratio of terephthalaldehyde and tetra(4-aminophenyl)methane is 1.2-2.4, preferably 1.5-1.8; the organic solvent vapor-assisted crystallization treatment method is as follows: exposed to an organic solvent anhydrous dioxane at a temperature of 120-150℃ and a pressure of 50-100kPa for 20-60h.

[0016] Further, in step (4), the method for preparing the noble metal salt mixed solution is as follows: 20-40 mg of noble metal salt is added to 3-6 ml of organic solvent, and after stirring, a uniform mixture is formed to obtain the noble metal salt mixed solution; the noble metal salt is PdCl2 or PtCl4, and the organic solvent is methanol; the parameters for the thermal evaporation treatment in the organic solvent vapor are: under argon protection, exposed to methanol vapor at a temperature of 100-135℃ and a pressure of 50-100 kPa for 18-54 h; the glow discharge treatment is: argon plasma cleaning is performed with a power of 100-300 W and a plasma cleaning time of 5-20 min.

[0017] Further, in steps (2) to (4), the parameters for the lifting coating are: lifting speed of 5-15 mm / min, coating time of 10-45 s, and lifting times of 1-5 times.

[0018] Invention principle: In this invention, the noble metal@covalent organic compound COFs@MOS@carbon hollow nanosphere composite film has a three-dimensional porous structure, thus having a large specific surface area, providing a large number of active sites, reducing the activation energy of the reaction, thereby reducing the device's operating temperature requirements, and thus reducing the device's power consumption. This is beneficial for improving the response intensity and sensitivity to methyl heptenone gas, while also improving the repeatability and long-term stability of the device's sensing performance. Covalent organic compounds form high-quality heterojunctions with semiconductor metal oxide quantum crystals and hollow carbon nanospheres. The hollow carbon nanospheres are grown in situ on the planar sensor device, and the semiconductor metal oxide quantum crystals are in full contact with the hollow carbon nanospheres. The covalent organic compounds interact with the hollow nanospheres to form a core-shell structure, which effectively improves electron transport capability and gas-sensing activity, solving the technical problems of low gas-sensing activity and unstable impedance of semiconductor metal oxide nanospheres. At the same time, due to the good conductivity of the hollow carbon nanospheres, they are uniformly dispersed in the composite film, which greatly increases the electron transport capability, thereby achieving high sensitivity and high selectivity sensing performance for methylheptenone. When the diameter of the hollow carbon nanospheres is between 100-150 nm, the array formed by the nanospheres is the most stable, and the sensing performance of the resulting composite film material is optimal.

[0019] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0020] (1) Low operating temperature and high sensitivity to gases;

[0021] (2) It exhibits high selectivity, good reproducibility, and good stability for methylheptenone;

[0022] (3) It is low in cost, simple in preparation method, and can be produced on a large scale. Attached Figure Description

[0023] Figure 1 This is a scanning electron microscope image of the Pt@COFs@indium oxide@carbon hollow nanosphere composite film prepared in Example 1 of the present invention;

[0024] Figure 2 The image shows the response test results of the sensor prepared in Example 1 of this invention to different concentrations of methylheptenone gas.

[0025] Figure 3 This is a test graph showing the sensing performance of the sensor prepared in Example 1 of the present invention at 2 ppm methyl heptenone under different humidity conditions.

[0026] Figure 4 This is a test chart of the selectivity of the sensor obtained in Embodiment 1 of the present invention for different gases;

[0027] Figure 5 This is a test graph showing the response of the sensor prepared in Example 2 of the present invention to different concentrations of methylheptenone gas. Detailed Implementation

[0028] The present invention will now be further described in conjunction with specific embodiments and accompanying drawings.

[0029] Example 1: The Pt@COFs@indium oxide@carbon hollow nanosphere composite film of the present invention uses carbon hollow nanospheres as a substrate, on which metal oxide semiconductor (MOS) quantum grains, covalent organic compounds (COFs) and Pt are sequentially loaded. The sensor uses the sensor device as a substrate, and a Pt@COFs@indium oxide@carbon hollow nanosphere composite film with a thickness of 700-800 nm is deposited on the substrate surface for the detection of methylheptenone gas.

[0030] The method for manufacturing the above-mentioned sensor includes the following steps:

[0031] (1) The basic characteristics of the sensor are: silicon substrate, silicon dioxide is deposited on the silicon substrate, then titanium layer and platinum layer are deposited, and finally platinum interdigitated electrode array is etched on the surface. Each platinum interdigitated electrode has a width of 10μm and a length of 1mm, the interdigitated electrode spacing is 8μm, and the interdigitated electrodes overlap by 800μm.

[0032] In the synthesis of carbon hollow nanospheres loaded onto a sensor, 0.15 ml of concentrated ammonia, 0.03 ml of (37 wt%) formaldehyde solution, and 0.03 g of 3-aminophenol were added to 2.85 ml of deionized water under vigorous stirring for 60 min. Then, 6.75 ml of acetone was added to the mixture to remove oligomers, and stirring continued for 20 min. Afterward, the mixture was rotary evaporated. When the solution volume was concentrated to half, it was ready for subsequent coating. The concentrated mixture was dip-coated onto the sensor at a speed of 10 mm / min, and the sensor was immersed in the mixture for 25 s under Ar protection. This coating process was repeated twice. The sensor containing carbon hollow nanospheres was collected by freeze-drying. The collected sensor containing carbon hollow nanospheres was carbonized at 800 °C for 3 h under a nitrogen atmosphere to obtain a sensor with a carbon hollow nanosphere film.

[0033] (2) 1 g of indium trichloride was added to 5 ml of ethanol solution containing 0.35 g of F127. Then, 0.2 ml of 12 M HCl was added dropwise to the precursor solution by ultrasonic dispersion with ultrasonic assistance, and ultrasonic dispersion was carried out for 5 min. Under Ar atmosphere protection, the precursor solution was dip-coated onto the sensor device loaded with carbon hollow nanospheres at a speed of 20 mm / min. The sensor device was immersed in the solution for 25 s, and this was repeated 3 times. After each dip-coating, the sensor device was dried at 60 °C for 1 h. The dried sensor device was placed in a sealed container and subjected to water vapor-assisted crystallization treatment: the sensor device was placed in a sealed container and exposed to water vapor with 95% relative humidity at 150 °C for 40 h. After treatment, the sensor device was subjected to glow discharge treatment: oxygen plasma treatment (frequency 40 kHz, power 300 W) was carried out for 10 min to obtain the sensor device loaded with indium oxide@carbon hollow nanosphere composite film.

[0034] (3) Measure 0.9 mmol of terephthalaldehyde and 0.5 mmol of tetra(4-aminophenyl)methane in an argon-filled glove box, and add 10 ml of anhydrous dioxane. With the aid of ultrasound, add 2 ml of 3M acetic acid solution to the sample tube and continue sonication for 5 min. Under argon protection, perform a coating operation on the above mixture at a speed of 10 mm / min. The sensor device loaded with indium oxide@carbon hollow nanosphere composite film is immersed in the mixture for 30 s each time, and the coating is repeated 3 times. Under argon protection, the above sensor device is placed in anhydrous dioxane vapor at a temperature of 130℃ and a pressure of 50 kPa for 40 h to induce self-assembly. After the reaction is completed, the sensor device is taken out, cleaned with anhydrous acetone, and then immersed in anhydrous tetrahydrofuran for 24 h. Vacuum dry at 60℃ for 20 h to obtain the sensor device loaded with COFs@indium oxide@carbon hollow nanosphere composite film;

[0035] (4) Add 20 mg PtCl4 to 4 ml methanol and stir magnetically for 1 h to obtain a noble metal salt mixed solution. Under argon protection, immerse the sensor device loaded with COFs@indium oxide@carbon hollow nanosphere composite film into the noble metal salt mixed solution for dip-coating. Dry the coated device at 50 °C for 12 h, and then expose the sensor device to methanol vapor at 100 °C and 100 kPa for 24 h under argon protection. Rinse the vapor-treated sensor device with acetone, then dry it under vacuum for 12 h, and finally treat the sensor device with argon plasma (frequency 40 kHz, power 300 W) for 10 min to obtain a sensor based on Pt@COFs@indium oxide@carbon hollow nanosphere composite film.

[0036] XPS surface elemental analysis revealed that the molar proportions of carbon hollow nanospheres, indium oxide, COFs, and Pt in the Pt@COFs@indium oxide@carbon hollow nanosphere composite film were 24%, 40%, 30%, and 6%, respectively.

[0037] like Figure 1 The composite hollow nanospheres used to construct the composite thin film have an average particle size of 700-800 nm and an average pore wall thickness of 200-300 nm. The carbon hollow nanospheres have an average diameter of 100-150 nm. The metal oxide semiconductor quantum dot grains have an average particle size of 3-5 nm. The thin film layer formed by COFs has an average thickness of 80-120 nm.

[0038] Performance testing was conducted on a gas sensor with a surface-loaded Pt@COFs@indium oxide@carbon hollow nanosphere composite film. The gas sensor was first operated at a specific voltage. After the initial baseline stabilized, a corresponding concentration of methylheptenone gas was introduced. Once the sensor resistance decreased and reached equilibrium, air was introduced into the test chamber until the baseline stabilized again. The corresponding gas-sensing test data was collected by a computer, completing the gas-sensing test. The real-time response curves of the sensor to methylheptenone concentrations of 0.2-25 ppm at room temperature are shown below. Figure 2 As shown. From Figure 2 As can be seen, the sensor exhibits a rapid increase in size with increasing gas concentration; when the concentration of methyl heptenone gas is 0.2-25 ppm, the sensor shows good correlation characteristics with the output characteristic curve of methyl heptenone.

[0039] The gas sensor with surface-loaded composite thin film was tested for performance under different humidity conditions: First, the gas sensor was operated at room temperature. After the initial baseline stabilized, methyl heptenone gas at concentrations of 2 ppm under different humidity conditions, such as 50%, 70%, and 90%, was introduced. Once the resistance of the gas sensor decreased and reached equilibrium, air was introduced into the test chamber until the baseline stabilized again, completing the gas sensor test. Figure 3It can be seen that the sensitivity of the gas sensor remains basically constant after the humidity exceeds 70%. Even at 90% humidity, the sensitivity remains high, with a sensitivity of 95.1 for 2 ppm methylheptenone gas, enabling rapid detection of methylheptenone. The sensor's response time is less than 7 seconds, and its recovery time is less than 5 seconds. Gas selectivity tests were performed on the gas sensor with a surface-loaded composite thin film, such as... Figure 4 As shown, the gas sensor's sensitivity to methylheptenone is much higher than that to toluene, isopropanol, diethyl ether, formaldehyde, acetone, and ethanol, and is more than three times higher than that to other target gases, indicating that the gas sensor has excellent selectivity for methylheptenone gas.

[0040] Example 2: The Pt@COFs@titanium oxide@carbon hollow nanosphere composite film of the present invention uses carbon hollow nanospheres as a substrate, on which titanium oxide, covalent organic compounds COFs and Pt are sequentially loaded. The sensor uses a sensor device as a substrate, and a Pt@COFs@titanium oxide@carbon hollow nanosphere composite film with a thickness of 700-800 nm is deposited on the substrate surface for the detection of methylheptenone gas.

[0041] The method for manufacturing the above-mentioned sensor includes the following steps:

[0042] (1) The basic characteristics of the sensor are: silicon substrate, silicon dioxide is deposited on the silicon substrate, then titanium layer and platinum layer are deposited, and finally platinum interdigitated electrode array is etched on the surface. Each platinum interdigitated electrode has a width of 10μm and a length of 1mm, the interdigitated electrode spacing is 8μm, and the interdigitated electrodes overlap by 800μm.

[0043] In the synthesis of carbon hollow nanospheres loaded onto a sensor, 0.25 ml of concentrated ammonia, 0.04 ml of (37 wt%) formaldehyde solution, and 0.04 g of 3-aminophenol were added to 3.25 ml of deionized water under vigorous stirring for 40 min. Then, 7.5 ml of acetone was added to the mixture to remove oligomers, and stirring continued for 30 min. Afterward, the mixture was rotary evaporated. When the solution volume was concentrated to half, it was ready for subsequent coating. The concentrated mixture was dip-coated onto the sensor at a speed of 8 mm / min, and the sensor was immersed in the mixture for 20 s under Ar protection. This coating process was repeated twice. The sensor containing carbon hollow nanospheres was collected by freeze-drying. The collected sensor containing carbon hollow nanospheres was carbonized at 700 °C for 3 h under a nitrogen atmosphere to obtain a sensor with a carbon hollow nanosphere film.

[0044] (2) 1g TiCl4 was added to 5.5ml of ethanol solution containing 0.38g F127. Then, 0.3ml of 12M HCl was added dropwise to the precursor solution by ultrasonic-assisted dispersion for 8min. Under Ar atmosphere protection, the precursor solution was dip-coated onto the sensor device loaded with carbon hollow nanosphere film at a speed of 15mm / min. The sensor device was immersed in the solution for 20s, and this was repeated 5 times. After each dip-coating, the sensor device was dried at 60℃ for 1h. The dried sensor device was placed in a sealed container and subjected to water vapor-assisted crystallization treatment: the sensor device was placed in a sealed container and exposed to water vapor with 85% relative humidity at 140℃ for 50h. After treatment, the sensor device was subjected to glow discharge treatment: oxygen plasma treatment (frequency 40kHz, power 300W) was used for 15min to obtain the sensor device loaded with titanium oxide@carbon hollow nanosphere composite film.

[0045] (3) Measure 1.0 mmol of terephthalaldehyde and 0.6 mmol of tetra(4-aminophenyl)methane in an argon-filled glove box, and add 12 ml of anhydrous dioxane. With the aid of ultrasound, add 2.5 ml of 3M acetic acid solution to the sample tube and continue sonication for 8 minutes. Under argon protection, perform a coating operation on the above mixture at a speed of 15 mm / min. The sensor device loaded with titanium dioxide@carbon hollow nanosphere composite film is immersed in the mixture for 25 s each time, and the coating is repeated 3 times. Under argon protection, the above sensor device is placed in anhydrous dioxane vapor at a temperature of 120℃ and a pressure of 80 kPa for induced self-assembly treatment for 50 h. After the reaction is completed, the sensor device is taken out, cleaned with anhydrous acetone, and then immersed in anhydrous tetrahydrofuran for 24 h. Vacuum dry at 60℃ for 18 h to obtain the sensor device loaded with COFs@titanium dioxide@carbon hollow nanosphere composite film;

[0046] (4) Add 30 mg PtCl4 to 5 ml methanol and stir magnetically for 1 h to obtain a noble metal salt mixed solution. Under argon protection, immerse the sensor device loaded with COFs@titanium oxide@carbon hollow nanosphere composite film into the noble metal salt mixed solution for dip-coating. Dry the coated device at 50 °C for 12 h, and then expose the sensor device to methanol vapor at 120 °C and 80 kPa for 26 h under argon protection. Rinse the vapor-treated sensor device with acetone, then dry it under vacuum for 12 h, and finally treat the sensor device with argon plasma (frequency 40 kHz, power 300 W) for 15 min to obtain a sensor based on Pt@COFs@titanium oxide@carbon hollow nanosphere composite film.

[0047] XPS surface elemental analysis revealed that the molar percentages of carbon hollow nanospheres, titanium oxide, COFs, and Pt in the composite film were 27%, 34%, 36%, and 3%, respectively.

[0048] The real-time response curves of the composite thin-film gas sensor to methyl heptenone concentrations of 0.2-25 ppm at room temperature are shown in the figure below. Figure 5 As shown, from Figure 5 As can be seen, when the concentration of methylheptenone gas is 0.2-25 ppm, the correlation characteristics of the sensor's output characteristic curve for methylheptenone are very good.

Claims

1. A sensor based on noble metal @ COFs @ MOS @ carbon hollow nanosphere composite film, characterized in that, The sensor takes a sensor device as a substrate, and a noble metal@COFs@MOS@carbon hollow nanosphere composite film is deposited on the surface of the substrate; the noble metal@COFs@MOS@carbon hollow nanosphere composite film takes carbon hollow nanospheres as a substrate, and is sequentially loaded with metal oxide semiconductor quantum grains, COFs and noble metal on the substrate; the composite film includes composite hollow nanospheres, the composite nanosphere has a carbon nanosphere as an inner layer, a MOS quantum grain as an intermediate layer, and COFs as an outermost layer; the sensor is used for detecting methyl heptenone gas; and the preparation method of the sensor based on the noble metal@COFs@MOS@carbon hollow nanosphere composite film includes the following steps: (1) carbon hollow nanospheres are prepared on the surface of a sensor device to obtain a sensor device with a carbon hollow nanosphere film; (2) the sensor device with the carbon hollow nanosphere film is put into a MOS precursor solution for pull-up film plating, taken out, dried, placed in a sealed environment, treated by water vapor assisted crystallization, and then subjected to glow treatment to obtain a sensor device with a MOS@carbon hollow nanosphere composite film; (3) the sensor device with the MOS@carbon hollow nanosphere composite film is immersed in a COFs precursor solution in a protective gas for pull-up film plating, taken out, dried, and subjected to organic solvent vapor assisted crystallization treatment to obtain a sensor device with a COFs@MOS@carbon hollow nanosphere composite film; (4) in a protective gas, the sensor device loaded with COFs@MOS@carbon hollow nanosphere composite film is immersed in a mixed solution of noble metal salt for pull-coating film deposition, and after drying, the sensor device is placed in an organic solvent vapor for heat steaming treatment, and after the treatment, the sensor device is subjected to glow treatment, to obtain a sensor based on noble metal@COFs@MOS@carbon hollow nanosphere composite film; in step (1), the step of preparing carbon hollow nanospheres on the surface of the sensor device is as follows: under a protective gas, a carbon hollow nanosphere precursor concentrated solution is dip-coated on the sensor device, and after freeze-drying collection, the sensor device is subjected to carbonization treatment in an inert gas, to obtain the carbon hollow nanospheres; the preparation method of the carbon hollow nanosphere precursor concentrated solution is as follows: under high stirring speed, water, ammonia water, formaldehyde and 3-aminophenol are mixed, and then acetone is added to remove oligomers, and the obtained mixed solution is subjected to rotary evaporation, to obtain the carbon hollow nanosphere precursor concentrated solution; the volume percentage of the water, ammonia water, formaldehyde and 3-aminophenol is 90-95%, 4-8%, 1-3% and 1-3%, respectively, and the volume of the acetone is 3-5 times that of the total volume of the water, ammonia water, formaldehyde and 3-aminophenol; the carbonization treatment conditions are as follows: carbonization at 750-850 ℃ for 2-4 h; in step (2), the preparation method of the metal oxide semiconductor MOS precursor solution is as follows: a metal oxide semiconductor precursor is dissolved in an organic solvent, and a surfactant is added and uniformly mixed, to obtain a precursor sol solution, and then hydrochloric acid is added dropwise into the precursor solution, and ultrasonic dispersion is performed by means of ultrasonic waves, to obtain the metal oxide semiconductor precursor solution; the metal oxide semiconductor precursor is indium trichloride, zinc dichloride or titanium tetrachloride, the organic solvent is anhydrous ethanol, anhydrous isopropanol or anhydrous butanol, the mass of the metal oxide semiconductor precursor to the volume of the organic solvent is 1.0-2.0 g:5-10 ml, and the surfactant is P123, F127 or Brij35; in step (3), the preparation method of the covalent organic compound COFs precursor solution is as follows: in a protective gas, p-xylylene formaldehyde and tetra(4-aminophenyl)methane are dissolved in anhydrous dioxane, to obtain a mixed solution; under ultrasonic assistance, an aqueous acetic acid solution is added into the mixed solution, and after ultrasonic treatment, vacuum treatment is performed, to obtain the covalent organic compound COFs precursor solution; the molar ratio of the p-xylylene formaldehyde to the tetra(4-aminophenyl)methane is 1.2-2.4; the organic solvent vapor assisted crystallization treatment method is: exposed to temperature of 120-150 ℃, pressure of 50-100 kPa, protective atmosphere is handled with organic solvent anhydrous dioxane for 20-60 h;In step (4), the preparation method of the noble metal salt mixed solution is: 20-40 mg of noble metal salt is added to 3-6 ml of organic solvent, and a uniform mixture is formed after stirring, namely the noble metal salt mixed solution;The noble metal salt is PdCl2 or PtCl4, and the organic solvent is methanol;The parameters of the heat steaming treatment in the organic solvent vapor are: under the protection of argon, exposed to methanol vapor with temperature of 100-135 ℃, pressure of 50-100 kPa, keep for 18-54 h;The glow treatment is: argon plasma cleaning is carried out, the power is 100-300 W, and the plasma cleaning time is 5-20 min.

2. The sensor of claim 1, wherein, The molar ratio of the carbon hollow nanosphere, the metal oxide semiconductor quantum grain, the COFs and the noble metal in the composite film is 18-27%, 33-40%, 27-36% and 3-6% respectively; the average diameter of the composite hollow nanosphere is 700-800 nm, the average wall thickness is 200-300 nm, and the average diameter of the carbon hollow nanosphere is 100-150 nm; the average particle size of the metal oxide semiconductor quantum dot grain is 3-5 nm, and the average thickness of the COFs film layer is 80-120 nm.

3. The sensor of claim 1, wherein, The thickness of the noble metal@COFs@MOS@carbon hollow nanosphere composite film is 700-800 nm.

4. The sensor of claim 1, wherein, In steps (2)-(4), the parameters of the pull-up film plating are as follows: the pull-up speed is 5-15 mm / min, the film plating time is 10-45 s, and the pull-up frequency is 1-5 times.

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