Modified MOFs-derived Co3O4 gas-sensitive material as well as preparation method and application thereof

Abstract

The invention discloses a modified MOFs-derived Co3O4 gas-sensitive material as well as a preparation method and application thereof, and belongs to the technical field of gas-sensitive materials. The modified MOFs-derived Co3O4 gas-sensitive material is used for preparing an MEMS gas sensor and is used for detecting the concentration of methane, and the MEMS gas sensor based on the material has relatively high sensitivity and selectivity on trace methane gas at room temperature. The method can be widely applied to the fields of industrial safety, environment monitoring, smart home and the like, and has important application value.

Description

Technical Field

[0001] The present invention belongs to the technical field of gas-sensitive materials, and specifically relates to a modified MOFs-derived Co3O4 gas-sensitive material and a preparation method and application thereof. Background Art

[0002] Methane, a colorless, odorless, flammable gas, is not only a major component of natural gas but also poses a risk of leakage in areas such as coal mining and sewage treatment, potentially leading to explosions or suffocation. Furthermore, medical research has shown that abnormal methane concentrations in human exhaled breath are associated with intestinal diseases (such as irritable bowel syndrome), making it a biomarker for noninvasive diagnosis. Therefore, the development of highly sensitive, low-cost methane sensors is of great significance for industrial safety, environmental monitoring, and medical diagnosis.

[0003] Metal oxide semiconductor gas sensors have attracted widespread attention due to their low cost, high sensitivity, and fast response / recovery speeds. They are the preferred materials for gas sensors. Therefore, metal oxide semiconductor gas sensors are well suited for real-time, continuous, and online monitoring.

[0004] The detection mechanism of metal oxide semiconductor gas sensors relies on thermally activated surface reactions—external energy excites active sites on the surface of the sensitive material, prompting chemical adsorption of target gas molecules, thereby changing the material's carrier concentration and conductivity, ultimately outputting a quantifiable electrical signal. These sensors typically operate in high-temperature environments of 200-400°C, hindering device integration and power consumption control. Summary of the Invention

[0005] Provided are a modified MOFs-derived Co3O4 gas-sensitive material, a preparation method, and an application thereof, in order to solve the technical problems of high operating temperature, poor sensitivity, and poor integration of metal oxide semiconductor gas sensors currently used for detecting trace methane gas.

[0006] The technical solutions of the present invention are as follows:

[0007] In a first aspect, the present invention provides a method for preparing a modified MOFs-derived Co3O4 gas-sensitive material, comprising:

[0008] Prepare a methanol solution of Co(NO3)2·6H2O and C4H6N2 (dimethylimidazole), mix the methanol solution of Co(NO3)2·6H2O and the methanol solution of C4H6N2 evenly, and let it stand for aging;

[0009] The aged solution is centrifuged and the precipitate is collected, washed and dried;

[0010] The dried precipitate is redispersed in a solution containing a cobalt salt and subjected to a hydrothermal reaction;

[0011] The solution after the hydrothermal reaction is centrifuged and the precipitate is collected, washed and dried;

[0012] calcining the dried precipitate;

[0013] The above reaction mechanism is as follows: In methanol solution, the nitrogen atom in the C4H6N2 molecule contains a lone pair of electrons, which can react with Co 2+ Through the bidentate coordination characteristics of the C4H6N2 bridging ligand, each Co 2+ It forms a tetrahedral coordination structure with four nitrogen atoms, thereby self-assembling into a porous ZIF-67 framework material with sodalite topology. 2+ It was partially dissolved from ZIF-67 and re-coordinated with free C4H6N2 under hydrothermal conditions, while the additional Co 2+ Participate in dynamic equilibrium, resulting in controlled etching of the ZIF-67 surface accompanied by structural reorganization. Finally, the ZIF-67 modified by hydrothermal reaction acts as a self-sacrificial template during the calcination process, and its organic ligand (C4H6N2) decomposes and volatilizes under heat. 2+ Oxidation generates Co3O4 nanoparticles, while the metal nodes are retained and reorganized into an oxide framework. The hydrothermal reaction modification process induces an increase in the concentration of oxygen vacancies on the metal oxide surface, improving the material's sensitivity to trace methane gas.

[0014] In some embodiments, the concentration of the methanol solution of Co(NO3)2·6H2O is 0.02-0.04 g / ml, and the concentration of the methanol solution of C4H6N2 is 0.018-0.037 g / ml.

[0015] In some embodiments, the static aging time is 6 to 24 hours, and the static aging temperature is room temperature.

[0016] In some embodiments, the cobalt salt is Co(NO3)2·6H2O, and the solvent of the solution is anhydrous ethanol.

[0017] In some embodiments, the concentration of the solution containing the cobalt salt is 0.001-0.01 g / ml.

[0018] In some embodiments, the temperature of the hydrothermal reaction is 100-150° C., and the reaction time is 1-2 h.

[0019] In some embodiments, the calcination temperature is 300-400° C., and the calcination time is 1-3 hours.

[0020] In a second aspect, the present invention provides a modified MOFs-derived Co3O4 gas-sensitive material prepared by the above-mentioned method for preparing a modified MOFs-derived Co3O4 gas-sensitive material.

[0021] In a third aspect, the present invention provides an application of the modified MOFs-derived Co3O4 gas-sensitive material as described above, wherein the modified MOFs-derived Co3O4 gas-sensitive material is made into a gas-sensitive material ink and printed on a MEMS micro-hotplate gas sensor body.

[0022] In some embodiments, a modified MOFs-derived Co3O4 gas-sensitive material is ground and mixed with anhydrous ethanol to form a gas-sensitive material ink, which is then printed on a flat substrate with a gold electrode of a MEMS micro-hotplate gas sensor, dried to form a film, and aged to obtain a modified MOFs-derived Co3O4 gas sensor for detecting trace methane gas at room temperature.

[0023] The beneficial effects of the present invention are:

[0024] This invention uses a modified MOF-derived Co₃O₄ gas-sensitive material to fabricate a MEMS gas sensor for detecting methane concentration. This MEMS gas sensor exhibits high sensitivity and selectivity for trace methane at room temperature. It has significant application value in a wide range of fields, including industrial safety, environmental monitoring, and smart homes. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a flow chart of the preparation method of Examples 1 to 4 of the present invention;

[0026] Figure 2 SEM images of ZIF-67, ZIF-67-50, ZIF-67-100, ZIF-67-300 and derived Co3O4, Co3O4-50, Co3O4-100, and Co3O4-300 prepared in Examples 1 to 4: a: ZIF-67; b: ZIF-67-50; c: ZIF-67-100; d: ZIF-67-300; e: Co3O4; f: Co3O4-50; g: Co3O4-100; h: Co3O4-300;

[0027] Figure 3 X-ray diffraction patterns of Co3O4, Co3O4-50, Co3O4-100, and Co3O4-300 prepared in Examples 1 to 4;

[0028] Figure 4 Dynamic gas-sensitive response curves of Co3O4, Co3O4-50, Co3O4-100, and Co3O4-300 prepared in Examples 1 to 4 to methane at the same concentration at room temperature;

[0029] Figure 5 The dynamic gas-sensitive response curve of Co3O4-100 prepared in Example 3 to the same concentration of methane at different working temperatures;

[0030] Figure 6 This is the dynamic gas-sensitive response curve of Co3O4-100 prepared in Example 3 to different concentrations of methane at room temperature;

[0031] Figure 7 Comparison of the gas-sensitive responses of Co3O4-100 prepared in Example 3 to different gases at room temperature. DETAILED DESCRIPTION

[0032] In order to clarify the innovation, implementation path and technical advantages of this technical solution, the embodiments of the present invention are now systematically explained. It should be noted that the embodiments described below are only representative examples of the technical solution of the present invention, and their number and specific forms do not constitute a limitation on the scope of protection. According to the embodiments recorded in this specification, any equivalent implementation scheme derived by any person skilled in the art based on conventional technical means, as long as it does not deviate from the core design concept of the present invention and does not make creative work, should be deemed to fall within the protection scope of the patent of the present invention.

[0033] Example 1 Preparation of MOFs-derived Co3O4

[0034] The following steps are involved:

[0035] Step 1: Dissolve 0.582 g of Co(NO3)2·6H2O and 1.312 g of C4H6N2 in 25 ml and 70 ml of anhydrous methanol, respectively, and stir at room temperature for 10 min to obtain a methanol solution of Co(NO3)2·6H2O and a methanol solution of C4H6N2;

[0036] Step 2: Mix the methanol solution of Co(NO3)2·6H2O obtained in step 1 with the methanol solution of C4H6N2, and stir them thoroughly at room temperature to obtain a mixed solution;

[0037] Step 3: The mixed solution obtained in step 2 was aged at room temperature for 24 hours, and then centrifuged; the centrifuged product was washed three times with anhydrous methanol and dried at 60°C for 24 hours to obtain a ZIF-67 precursor, which was named ZIF-67.

[0038] Step 4: Transfer the ZIF-67 obtained in step 3 to a muffle furnace, raise the temperature from room temperature to 300°C~400°C at a rate of 1~3°C / min, and maintain it for 1~3h to obtain a MOFs-derived Co3O4 sensitive material, named Co3O4.

[0039] The SEM images of ZIF-67 and Co3O4 obtained in this example are as follows Figure 2 a, b in the figure, and the X-ray diffraction pattern of Co3O4 are as follows: Figure 3 Co3O4 curve in.

[0040] Example 2 Preparation of Modified MOFs-Derived Co3O4-50

[0041] Step 1: Dissolve 0.582 g of Co(NO3)2·6H2O and 1.312 g of C4H6N2 in 25 ml and 70 ml of anhydrous methanol, respectively, and stir at room temperature for 10 min to obtain a methanol solution of Co(NO3)2·6H2O and a methanol solution of C4H6N2;

[0042] Step 2: Mix the methanol solution of Co(NO3)2·6H2O obtained in step 1 with the methanol solution of C4H6N2, and stir them thoroughly at room temperature to obtain a mixed solution;

[0043] Step 3: The mixed solution obtained in step 2 was aged at room temperature for 24 hours, and then centrifuged; the centrifuged product was washed three times with anhydrous methanol and dried at 60°C for 24 hours to obtain a ZIF-67 precursor.

[0044] Step 4: Dissolve 50 mg of Co(NO3)2·6H2O in 30 ml of anhydrous ethanol and stir at room temperature for 10 minutes to obtain an ethanol solution of Co(NO3)2·6H2O;

[0045] Step 5: Dissolve 100 mg of ZIF-67 obtained in step 3 in the ethanol solution of Co(NO3)2·6H2O obtained in step 4, and disperse evenly after ultrasonication for 3 minutes to obtain a mixed solution; transfer the mixed solution to a polytetrafluoroethylene-lined stainless steel autoclave for hydrothermal reaction at 100~150℃ for 1~2h to obtain the reactant.

[0046] Step 6: The reactant obtained in step 5 was washed with anhydrous ethanol three times and dried at 60° C. for 24 h to obtain a modified ZIF-67 precursor, named ZIF-67-50.

[0047] Step 7: Transfer the ZIF-67-50 obtained in step 6 to a muffle furnace, raise the temperature from room temperature to 300°C~400°C at a rate of 1~3°C / min, and maintain it for 1~3h to obtain a modified MOFs-derived Co3O4 sensitive material, named Co3O4-50.

[0048] The SEM images of ZIF-67-50 and Co3O4-50 obtained in this example are as follows: Figure 2 c, d in the figure, and the X-ray diffraction pattern of Co3O4-50 are as follows: Figure 3 Co3O4-50 curve in.

[0049] Example 3 Preparation of Modified MOFs-Derived Co3O4-100

[0050] Step 1: Dissolve 0.582 g of Co(NO3)2·6H2O and 1.312 g of C4H6N2 in 25 ml and 70 ml of anhydrous methanol, respectively, and stir at room temperature for 10 min to obtain a methanol solution of Co(NO3)2·6H2O and a methanol solution of C4H6N2;

[0051] Step 2: Mix the methanol solution of Co(NO3)2·6H2O obtained in step 1 with the methanol solution of C4H6N2, and stir them thoroughly at room temperature to obtain a mixed solution;

[0052] Step 3: The mixed solution obtained in step 2 was aged at room temperature for 24 hours, and then centrifuged; the centrifuged product was washed three times with anhydrous methanol and dried at 60°C for 24 hours to obtain a ZIF-67 precursor.

[0053] Step 4: Dissolve 100 mg of Co(NO3)2·6H2O in 30 ml of anhydrous ethanol and stir at room temperature for 10 minutes to obtain an ethanol solution of Co(NO3)2·6H2O;

[0054] Step 5: Dissolve 100 mg of ZIF-67 obtained in step 3 in the ethanol solution of Co(NO3)2·6H2O obtained in step 4, and disperse evenly after ultrasonication for 3 minutes to obtain a mixed solution; transfer the mixed solution to a polytetrafluoroethylene-lined stainless steel autoclave for hydrothermal reaction at 100~150℃ for 1~2h to obtain the reactant.

[0055] Step 6: The reactant obtained in step 5 was washed with anhydrous ethanol three times and dried at 60° C. for 24 h to obtain a modified ZIF-67 precursor, named ZIF-67-100.

[0056] Step 7: Transfer the ZIF-67-100 obtained in step 6 to a muffle furnace, raise the temperature from room temperature to 300°C~400°C at a rate of 1~3°C / min, and maintain it for 1~3h to obtain a modified MOFs-derived Co3O4 sensitive material, named Co3O4-100.

[0057] The SEM images of ZIF-67-100 and Co3O4-100 obtained in this example are as follows: Figure 2 e, f, X-ray diffraction patterns of Co3O4-100 are as follows Figure 3 Co3O4-50 curve in.

[0058] Example 4 Preparation of Modified MOFs-Derived Co3O4-300

[0059] Step 1: Dissolve 0.582 g of Co(NO3)2·6H2O and 1.312 g of C4H6N2 in 25 ml and 70 ml of anhydrous methanol, respectively, and stir at room temperature for 10 min to obtain a methanol solution of Co(NO3)2·6H2O and a methanol solution of C4H6N2;

[0060] Step 2: Mix the methanol solution of Co(NO3)2·6H2O obtained in step 1 with the methanol solution of C4H6N2, and stir them thoroughly at room temperature to obtain a mixed solution;

[0061] Step 3: The mixed solution obtained in step 2 was aged at room temperature for 24 hours, and then centrifuged; the centrifuged product was washed three times with anhydrous methanol and dried at 60°C for 24 hours to obtain a ZIF-67 precursor.

[0062] Step 4: Dissolve 300 mg of Co(NO3)2·6H2O in 30 ml of anhydrous ethanol and stir at room temperature for 10 minutes to obtain an ethanol solution of Co(NO3)2·6H2O;

[0063] Step 5: Dissolve 100 mg of ZIF-67 obtained in step 3 in the ethanol solution of Co(NO3)2·6H2O obtained in step 4, and disperse evenly after ultrasonication for 3 minutes to obtain a mixed solution; transfer the mixed solution to a polytetrafluoroethylene-lined stainless steel autoclave for hydrothermal reaction at 100~150℃ for 1~2h to obtain the reactant.

[0064] Step 6: The reactant obtained in step 5 was washed with anhydrous ethanol three times and dried at 60° C. for 24 h to obtain a modified ZIF-67 precursor, named ZIF-67-300.

[0065] Step 7: Transfer the ZIF-67-300 obtained in step 6 to a muffle furnace, raise the temperature from room temperature to 300°C~400°C at a rate of 1~3°C / min, and maintain it for 1~3h to obtain a modified MOFs-derived Co3O4 sensitive material, named Co3O4-300.

[0066] The SEM images of ZIF-67-300 and Co3O4-300 obtained in this example are as follows: Figure 2 g, h, and the X-ray diffraction pattern of Co3O4-300 are as follows Figure 3 Co3O4-300 curve in.

[0067] Example 5 Material Characterization

[0068] Figure 2Figures ah in the figure are SEM images of ZIF-67, ZIF-67-50, ZIF-67-100, ZIF-67-300 and their derivatives Co3O4, Co3O4-50, Co3O4-100 and Co3O4-300, respectively. After the precursors were calcined at high temperature, the metal oxides obtained still retained the structure of the precursors, and they were composed of nanoparticles. In addition, during the hydrothermal reaction, ethanol solutions with different concentrations of Co(NO3)2·6H2O had a significant effect on the micromorphology of the precursors. In ethanol solutions with lower concentrations of Co(NO3)2·6H2O, nanosheets ( Figure 2 c), the calcined Co3O4-50 still retains the original dodecahedral structure, but the surface becomes rougher ( Figure 2 d in the figure), as the concentration of Co(NO3)2·6H2O in ethanol solution increases, more nanosheets grow on the surface of ZIF-67-100 ( Figure 2 e in the figure), when calcined at high temperature, the original dodecahedral structure collapses inward, and the single-layer shell self-assembles into a flower-like structure of Co3O4-100 ( Figure 2 f in the figure), when the concentration of Co(NO3)2·6H2O in ethanol solution is further increased, ZIF-67-300 shows the morphology of hollow open nanocages ( Figure 2 g in the figure), when calcined at high temperature, the local structure collapsed and the opening diameter increased, resulting in Co3O4-300 ( Figure 2 h in the text).

[0069] like Figure 3 As shown, by analyzing the X-ray diffraction patterns, it can be seen that the diffraction peaks of Co3O4, Co3O4-50, Co3O4-100, and Co3O4-300 prepared in Examples 1 to 4 of the present invention correspond one by one to the standard PDF card of Co3O4, which indicates that the hydrothermal reaction does not destroy the spinel structure of Co3O4.

[0070] Example 6 Application Effect

[0071] 1. Preparation of MEMS Micro-hotplate Gas Sensor

[0072] Anhydrous ethanol was poured into a mortar as a dispersion medium, and the Co3O4 materials prepared in Examples 1 to 4 were added in small amounts and multiple times, and ground to form a uniform printing ink. During the grinding process, acetic acid solution was simultaneously added dropwise to precisely control the pH value of the printing ink to the range of 6.0 to 7.5. The ink was then printed onto a flat substrate with gold electrodes on a MEMS micro-hotplate using electrohydrodynamic (EHD) printing technology, covering the gold electrodes to form a sensitive material film with controllable thickness. The MEMS micro-hotplate was heat-treated at 60°C for 12 to 24 hours, and then soldered to a ceramic tube shell using gold wire. The above device was heat-aged for one day to obtain a MEMS micro-hotplate gas sensor.

[0073] 2. Application effect impact test

[0074] 2.1 Effect of cobalt salt concentration in hydrothermal reaction

[0075] The methane gas sensitivity test was conducted on different sensors prepared from the MOFs-derived Co3O4 gas-sensitive materials modified with different cobalt salt concentrations in Examples 1 to 4. Specifically, 100 ppm methane gas was introduced at an operating temperature of 25°C. After the sensor responded, clean air was introduced again and the sensor was rinsed at 190°C for 3 minutes. The response of each sensor (R g / R a ).

[0076] Figure 4 The dynamic gas-sensitive response curves of different sensors prepared from MOFs-derived Co3O4 gas-sensitive materials modified with different cobalt salt concentrations in Examples 1 to 4 to 100 ppm methane at room temperature are shown. The experimental results show that the modified MOFs-derived Co3O4-100 gas-sensitive material of Example 3 has a better response to methane at room temperature, which is better than other modified samples. This is due to the improvement of sensitive sites on the material surface after hydrothermal modification, which facilitates the adsorption of target gas and realizes gas-sensitive response.

[0077] 2.2 Influence of operating temperature

[0078] The sensor prepared from the modified MOFs-derived Co3O4-100 gas-sensitive material of Example 3 was subjected to gas-sensing tests at different operating temperatures to determine its optimal operating temperature. Specifically, 100 ppm methane gas was introduced within the operating temperature range of 25-150°C. After the sensor responded, clean air was introduced again and the sensor was rinsed at 190°C for 3 minutes. The sensor response (R g / R a ).

[0079] Figure 5The dynamic gas-sensing response curves of a sensor fabricated using the modified MOFs-derived Co₃O₄-100 gas-sensitive material of Example 3 to the same methane concentration at different operating temperatures are shown. The experimental results demonstrate that the modified MOFs-derived Co₃O₄-100 gas-sensitive material of Example 3 exhibits the highest gas response at room temperature, outperforming other operating temperatures. Therefore, Co₃O₄-100 exhibits optimal methane detection performance at room temperature, making it suitable for room-temperature, high-sensitivity gas sensing applications.

[0080] 2.3 Impact of methane concentration

[0081] The sensor prepared from the modified MOFs-derived Co3O4-100 gas-sensitive material of Example 3 was subjected to methane gas sensitivity tests at different concentrations. Specifically, at an operating temperature of 25°C, different concentrations of methane gas (5ppm, 10ppm, 30ppm, 60ppm, and 100ppm) were continuously introduced within the same experimental time period. After the sensor responded to each concentration of methane gas, clean air was introduced again and the sensor was rinsed at 190°C after waiting for 3 minutes. The sensor's response to different methane concentrations (R g / R a ).

[0082] Figure 6 The dynamic gas-sensitive response curve of the sensor prepared from the modified MOFs-derived Co3O4-100 gas-sensitive material of Example 3 to different concentrations of methane at room temperature. The experimental results show that the modified MOFs-derived Co3O4-100 gas-sensitive material of Example 3 has a good gas-sensitive response to different concentrations of methane at room temperature, and the material has the ability to distinguish methane gases of different concentrations at room temperature.

[0083] 2.4 Detection gas selectivity

[0084] The sensor prepared from the modified MOFs-derived Co3O4-100 gas-sensitive material of Example 3 was subjected to selectivity tests for different gases, and the operating temperature was set at 25°C.

[0085] Figure 7 The gas-sensitive responses of the sensor prepared from the modified MOFs-derived Co3O4-100 gas-sensitive material of Example 3 to 100 ppm of different gases at room temperature were compared. The experimental results showed that the modified MOFs-derived Co3O4-100 gas-sensitive material of Example 3 had a significantly higher response value to 100 ppm methane at room temperature, and had certain selectivity compared to other gases.

[0086] Overall, the sensor prepared from the modified MOFs-derived Co3O4-100 gas-sensitive material exhibited the highest gas response at room temperature, outperforming the other samples. This suggests that the modified MOFs-derived Co3O4-100 gas-sensitive material has the best detection performance for trace methane gas at room temperature and is suitable for room-temperature, high-sensitivity gas sensing applications.

Claims

1. A method for preparing a modified MOFs-derived Co3O4 gas-sensitive material, characterized in that: The following steps are involved: S1. Prepare a methanol solution of Co(NO3)2·6H2O and C4H6N2, mix the methanol solution of Co(NO3)2·6H2O and the methanol solution of C4H6N2 evenly, and let it stand for aging; The aged solution is centrifuged and the precipitate is collected, washed, and dried to obtain ZIF-67; The concentration of the Co(NO3)2·6H2O methanol solution is 0.02~0.04g / ml, and the concentration of the C4H6N2 methanol solution is 0.018~0.037g / ml; S2, redispersing the dried precipitated ZIF-67 in a solution containing a cobalt salt and performing a hydrothermal reaction; The solution after the hydrothermal reaction is centrifuged and the precipitate is collected, washed, and dried; the concentration of the cobalt salt solution is 0.001-0.01 g / ml; S3. calcining the dried precipitate to obtain a gas-sensitive material.

2. The method for preparing a modified MOFs-derived Co3O4 gas-sensitive material according to claim 1, characterized in that: The static aging time is 6 to 24 hours, and the static aging temperature is room temperature.

3. The method for preparing a modified MOFs-derived Co3O4 gas-sensitive material according to claim 1, characterized in that: The cobalt salt in the cobalt salt-containing solution is Co(NO3)2·6H2O, and the solvent is anhydrous ethanol.

4. The method for preparing a modified MOFs-derived Co3O4 gas-sensitive material according to claim 1, characterized in that: The temperature of the hydrothermal reaction is 100-150° C., and the reaction time is 1-2 hours.

5. The method for preparing a modified MOFs-derived Co3O4 gas-sensitive material according to claim 1, characterized in that: The calcination temperature is 300-400° C., and the calcination time is 1-3 hours.

6. A modified MOFs-derived Co3O4 gas-sensitive material prepared according to the method for preparing a modified MOFs-derived Co3O4 gas-sensitive material according to any one of claims 1 to 5.

7. The use of the modified MOFs-derived Co3O4 gas-sensitive material according to claim 6, characterized in that: The modified MOFs-derived Co3O4 gas-sensitive material is made into gas-sensitive material ink and printed on the MEMS micro-hotplate gas sensor body.

8. The use of the modified MOFs-derived Co3O4 gas-sensitive material according to claim 7, characterized in that: The modified MOFs-derived Co3O4 gas-sensitive material is ground and mixed with anhydrous ethanol to form a gas-sensitive material ink, which is then printed on a flat substrate with a gold electrode of a MEMS micro-hotplate gas sensor, dried to form a film, and subjected to aging treatment to obtain a modified MOFs-derived Co3O4 gas sensor.

9. A modified MOFs-derived Co3O4 gas sensor according to claim 8, characterized in that: Used to detect methane gas at room temperature.

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