Application of PES / UiO-66 composite membrane in detection of characteristic decomposition component CO of C4F7N / CO2 mixed gas as gas sensitive material

Abstract

The application relates to application of a PES / UiO-66 composite film in detection of a characteristic decomposition component CO of C4F7N / CO2 mixed gas as a gas-sensitive material, wherein the PES / UiO-66 composite film is composed of a PES base body and UiO-66 crystals uniformly dispersed in the PES base body; in a specific application, when CO gas contacts a sensor constructed by the PES / UiO-66 composite film, charge transfer occurs, the resistance value of the sensor changes obviously, the rapid response of low-concentration CO and the high-selectivity detection are realized, and the problems of insufficient sensitivity or high temperature / auxiliary excitation in the prior art are solved.

Description

Technical Field

[0001] This invention belongs to the field of gas sensing and online monitoring technology of power equipment, and relates to a gas-sensitive material based on PES / UiO-66 composite membrane and its preparation and application. Background Technology

[0002] In recent years, with the increasing application of environmentally friendly high-voltage insulating gases in power systems, C4F7N / CO2 mixed gas, with its excellent insulation properties and extremely low global warming potential, is considered an ideal alternative to SF6.

[0003] However, during equipment operation, if partial discharge or arcing faults occur, the C4F7N / CO2 mixed gas will undergo pyrolysis or cracking reactions, generating decomposition products characterized by CO. Studies have shown that when the local temperature rises to approximately 350°C or higher, the C–C and C–N bonds in the C4F7N molecule break, generating CF3 free radicals and oxygen-containing active fragments. In the presence of CO2 or trace amounts of oxygen, these further react to generate CO, and its concentration is positively correlated with the fault intensity and duration (typically ranging from 50 to 800 ppm). If timely detection is not achieved, the accumulation of CO will not only lead to a decrease in the insulation strength of the mixed gas (when the CO volume fraction reaches 10%, the gas breakdown voltage can decrease by more than 12%), but also, due to the high toxicity and flammability of CO, it may threaten the safe operation of the equipment and the health of maintenance personnel. Therefore, achieving real-time online monitoring and early warning of CO has significant engineering application value.

[0004] In existing technologies, resistive gas sensors have been widely used for the detection of gas decomposition products due to their advantages such as compact structure, rapid response, high sensitivity, and low manufacturing cost. However, current research mainly focuses on monitoring C4F7N gas leakage or overall thermal decomposition products, and the development of highly sensitive and selective detection materials for CO gas remains insufficient. Furthermore, existing sensors often suffer from problems such as high operating temperatures (>200℃), limited sensitivity, or the need for external excitation sources (e.g., UV light), making it difficult to meet the practical requirements of power equipment for low power consumption, room temperature operation, and long-term stability.

[0005] Meanwhile, although existing technologies (such as the composite nanofiber membrane disclosed in CN119711177A) have developed gas-sensitive materials for the decomposition components of C4F7N / CO2 mixtures, they cannot meet the needs of real-time CO monitoring. The fundamental reason is that the material design is mismatched with the physicochemical properties of CO and the requirements of the detection scenario, specifically manifested as follows:

[0006] (1) Mismatch in the specificity of the test subjects:

[0007] Existing materials are mostly designed for fluorine-containing decomposition components of C4F7N (such as C3F6, CF3, etc.), and their sensing mechanism relies on the polar interaction between the fluorine-containing groups and the material surface (such as hydrogen bonding, dipole-dipole interaction); however, CO is a small carbon molecule with weak polarity (dipole moment 0.11D), and its binding energy with such materials is extremely low (usually <20kJ / mol), resulting in poor charge transfer efficiency and a resistance change rate generally below 5% (e.g., the response of CN119711177A to CO is negligible), making effective identification impossible.

[0008] (2) Lack of selective design:

[0009] The decomposition products of the C4F7N / CO2 mixture are complex (including CF3, HF, C2F6, etc.). Existing materials do not have specific recognition sites designed for CO and other components based on their molecular size (CO molecule diameter 0.376 nm) and chemical activity (CO's lone pair electrons easily coordinate with metal sites). For example, the nanofiber membrane of CN119711177A has a higher response to HF (resistance change rate of 12%) than CO, resulting in a detection error of more than 30%, which cannot meet the requirements for accurate monitoring under multi-component interference in power equipment.

[0010] (3) Conflict between working conditions and scenario requirements:

[0011] To improve the response to fluorine-containing components, existing materials often rely on high temperature (>200℃) or ultraviolet light excitation to enhance molecular adsorption activity. However, CO easily reacts with oxygen at high temperatures (2CO+O2=2CO2), leading to distortion of the detection signal. At the same time, power equipment requires sensors to operate for a long time at room temperature (25±5℃) and low power consumption (<10mW), and the high energy consumption characteristics of existing materials (such as heating module power >50mW) cannot be adapted.

[0012] (4) Insufficient detection capability at low concentrations:

[0013] The characteristic concentration range of CO in power equipment is 50~800ppm. Existing materials are unresponsive to CO concentrations <100ppm due to their loose sensitive layer structure (e.g., the porosity of electrospun nanofiber membranes is >70%) or low density of active sites. For example, the fiber membrane of CN119711177A has a resistance change rate of only 1.2% at 50ppm CO, which is far below the 5% threshold required for fault early warning. Summary of the Invention

[0014] The purpose of this invention is to provide an application of a PES / UiO-66 composite membrane as a gas-sensitive material for detecting CO, a characteristic decomposition component of C4F7N / CO2 mixtures, to achieve a specific gas-sensitive response to CO, a characteristic decomposition component of insulating gas C4F7N / CO2, which can be further applied to online monitoring and early warning of power equipment faults.

[0015] The objective of this invention can be achieved through the following technical solutions:

[0016] The application of a PES / UiO-66 composite membrane as a gas-sensitive material for detecting CO, a characteristic decomposition component of a C4F7N / CO2 mixture, wherein the PES / UiO-66 composite membrane is composed of a PES matrix and UiO-66 crystals uniformly dispersed in the PES matrix.

[0017] Furthermore, the PES / UiO-66 composite membrane is prepared through the following steps:

[0018] S1. Dissolve zirconium salt and organic ligand in a mixed solvent of DMF and ethanol, and react by heating to generate UiO-66 crystals. After centrifugation, washing and drying, UiO-66 powder is obtained.

[0019] S2. Disperse UiO-66 powder uniformly in an organic solvent containing polyethersulfone, add a coupling agent to form a homogeneous suspension, pour it onto a flat substrate, and after solvent evaporation and phase inversion treatment, dry or hot press to obtain a PES / UiO-66 composite film.

[0020] Furthermore, in S1, the zirconium salt is ZrCl4 or ZrOCl2・8H2O; the organic ligand is terephthalic acid or 2-aminoterephthalic acid; and the volume ratio of DMF to ethanol is 8~10:1.

[0021] Furthermore, in S1, the heating reaction temperature is 120~140℃, and the time is 16~24h.

[0022] Furthermore, in S2, the homogeneous suspension contains 10-15 wt% polyethersulfone, 5-20 wt% UiO-66 powder, and 0.1-0.5 wt% coupling agent.

[0023] Furthermore, in S2, the coupling agent is γ-aminopropyltriethoxysilane or γ-(2,3-epoxypropoxy)propyltrimethoxysilane.

[0024] Furthermore, in S2, the solvent evaporates at a temperature of 25~60℃ for 8~12 hours, and the relative humidity is ≤50%.

[0025] Furthermore, in S2, the phase transformation process employs a solvent-inducing phase separation method, using deionized water or a mixture of water and ethanol as the non-solvent. The phase transformation process occurs at room temperature. The use of deionized water or similar non-solvents here allows for gentle and sufficient mass transfer between the polymer (PES) and the solvent (DMF), facilitating the formation of a permeable porous network structure within the composite membrane. This structure ensures the membrane's mechanical stability while significantly increasing the gas diffusion rate and the contactable surface area of ​​the UiO-66 crystals, thereby substantially enhancing the sensor's response sensitivity and speed.

[0026] Furthermore, in S2, the thickness of the PES / UiO-66 composite film is 50~150μm.

[0027] Furthermore, when the PES / UiO-66 composite membrane comes into contact with CO gas as a gas-sensitive material, the efficient identification and response of CO gas can be achieved by detecting the change in the resistance value of the gas-sensitive material.

[0028] Compared with the prior art, the present invention has the following advantages:

[0029] (1) Significantly improved material dispersibility and interfacial bonding: By uniformly dispersing UiO-66 powder in PES solution and adding an appropriate amount of coupling agent (KH-550 or KH-560), the interfacial bonding between UiO-66 and PES matrix is ​​significantly enhanced, avoiding MOF particle agglomeration and improving the structural uniformity and stability of the composite membrane.

[0030] (2) The preparation process is mild and controllable: UiO-66 crystals are synthesized by solvothermal method, and a film-forming suspension is prepared by mechanical stirring and ultrasonic treatment, and then a composite membrane is formed by non-solvent-induced phase separation (NIPS). Compared with the existing high temperature or high energy consumption process, this method has a moderate temperature (casting 25~60℃), controllable operation, simple preparation process, and is easy to scale up production.

[0031] (3) Membrane structure and thickness are adjustable: By adjusting the solution ratio, casting conditions and phase transformation methods, uniform composite membranes with thicknesses ranging from 50 to 150 μm can be obtained. The membrane pore structure can be controlled by the NIPS method, thereby optimizing the gas diffusion path and sensitive surface area and improving sensing performance.

[0032] (4) High sensitivity and selective detection capability: The obtained PES / UiO-66 composite membrane, as a gas-sensitive material, can effectively detect carbon monoxide (CO) generated by the decomposition of C4F7N / CO2 mixed gas. During the specific detection, the composite membrane undergoes charge transfer under the action of CO gas, and the sensor resistance value changes significantly, realizing rapid response and high selective detection of low concentration CO, solving the problems of insufficient sensitivity or the need for high temperature / auxiliary excitation in the prior art.

[0033] (5) Suitable for low-power online monitoring at room temperature: The composite membrane can work at room temperature without the need for an additional excitation source (such as ultraviolet light) and has long-term stability. It is suitable for online real-time monitoring and fault early warning of power equipment, effectively improving equipment safety and the operational safety of maintenance personnel.

[0034] (6) Adaptable to industrialization: The materials and processes used are simple, controllable and scalable, making it easy to promote and apply in actual power equipment and sensors, taking into account both cost-effectiveness and performance advantages. Attached Figure Description

[0035] Figure 1 The image is a scanning electron microscope image (magnification: ×5000) of the PES / UiO-66 composite film of Example 1 of the present invention.

[0036] Figure 2 The resistivity response-recovery spectrum of the sensor in Example 1 to 100 ppm CO;

[0037] Figure 3 The resistive response-recovery spectrum of the sensor in Comparative Example 1 to 100 ppm CO is shown.

[0038] Figure 4 The resistive response-recovery spectrum of the sensor in Comparative Example 2 to 100 ppm CO;

[0039] Figure 5 The resistive response-recovery spectrum of the sensor in Comparative Example 3 to 100 ppm CO;

[0040] Figure 6 The resistive response-recovery spectrum of the sensor in Comparative Example 4 to 100 ppm CO;

[0041] Figure 7 The resistive response-recovery spectrum of the sensor in Comparative Example 5 to 100 ppm CO is shown. Detailed Implementation

[0042] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0043] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0044] As used herein, the terms "and / or," "or / and," and "and / or" encompass any one of two or more of the related listed items, as well as any and all combinations of the related listed items. These arbitrary and all combinations include any two related listed items, any more related listed items, or a combination of all related listed items. It should be noted that when at least three items are connected using at least two conjunctions selected from "and / or," "or / and," and "and / or," it should be understood that, in this application, the technical solution undoubtedly includes solutions connected by "logical AND," and also undoubtedly includes solutions connected by "logical OR."

[0045] In this application, the technical features described in an open-ended manner include both closed technical solutions consisting of the listed features and open technical solutions that include the listed features.

[0046] In this application, numerical ranges are referred to as continuous unless otherwise specified, and include the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be merged. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0047] This document only specifically discloses some numerical ranges. However, any lower limit can be combined with any upper limit to form an unspecified range; and any lower limit can be combined with other lower limits to form an unspecified range, just as any upper limit can be combined with any other upper limit to form an unspecified range. Furthermore, each individually disclosed point or single value can itself serve as a lower or upper limit and be combined with any other point or single value or with other lower or upper limits to form an unspecified range.

[0048] Unless otherwise specified, the temperature parameters in this application may be either constant temperature processing or processing within a certain temperature range. The constant temperature processing allows temperature fluctuations within the precision range controlled by the instrument, such as ±5°C, ±4°C, ±3°C, ±2°C, or ±1°C.

[0049] In this document, the term "suitable" as used in phrases such as "suitable combination," "suitable method," and "any suitable method" refers to the ability to implement the technical solution of this application, solve the technical problem of this application, and achieve the expected technical effect of this application.

[0050] In this application, terms such as "further," "even further," and "particularly" are used to describe purposes and indicate differences in content, but should not be construed as limiting the scope of protection of this application.

[0051] In this application, "optionally," "optionally," and "optional" mean that something is optional, that is, it means that it is selected from either "with" or "without." If there are multiple "optional" entries in a technical solution, unless otherwise specified, and there are no contradictions or mutual constraints, each "optional" entry shall be independent.

[0052] In the description of the application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0053] Unless otherwise specified, all preparations and tests described herein took place at 25°C.

[0054] The terms “comprising,” “including,” “containing,” “having,” “comprising,” or other variations thereof are intended to cover non-closed inclusion, and no distinction is made between these terms. The term “comprising” means that other steps and ingredients may be added without affecting the final result. The compositions and methods / processes of the present invention comprise, consist of, and substantially consist of the essential elements and limitations described herein, as well as any additional or optional ingredients, components, steps, or limitations described herein. No distinction is made between the terms “efficacy,” “performance,” “effect,” and “potency” herein.

[0055] Unless otherwise specified, all embodiments and optional embodiments of this application can be combined to form new technical solutions. Unless otherwise specified, all technical features and optional technical features of this application can be combined to form new technical solutions.

[0056] Unless otherwise specified, all steps of this application may be performed sequentially or randomly, but sequentially is preferred.

[0057] Example 1:

[0058] 0.233 g of zirconium tetrachloride (ZrCl4) and 0.166 g of terephthalic acid were dissolved in a mixed solvent of 45 mL of N,N-dimethylformamide (DMF) and 5 mL of ethanol. The solution was transferred to a 100 mL polytetrafluoroethylene-lined reactor and reacted at 130 °C for 20 hours using a solvothermal method. The reaction product was centrifuged and washed three times each with DMF and ethanol, and finally dried in a vacuum drying oven at 90 °C for 10 hours to obtain white UiO-66 powder. 0.15 g of this powder and 0.75 g of polyethersulfone (PES) were dispersed together in 8.1 g of DMF solvent, and 0.009 g of γ-aminopropyltriethoxysilane (KH-550) was added. The mixture was first mechanically stirred at 1100 rpm for 3.5 hours, and then sonicated at 45 kHz for 50 minutes to form a homogeneous film-forming solution. The solution was cast onto a horizontal glass substrate at 35°C and 40% relative humidity. After evaporation at room temperature for 10 hours, it was immersed in deionized water for phase inversion for 30 minutes. Finally, it was vacuum dried at 60°C to obtain a PES / UiO-66 composite film with a thickness of about 100 μm.

[0059] The PES / UiO-66 composite membrane prepared in Example 1 was tested, and the results are as follows:

[0060] (1) The PES / UiO-66 composite film material prepared in Example 1 was characterized by scanning electron microscopy (SEM). Figure 1 It can be seen that the UiO-66 particles are uniformly dispersed in the PES matrix, and the membrane structure is dense and without obvious defects.

[0061] (2) The PES / UiO-66 composite film material prepared in Example 1 was attached to an interdigitated electrode (using a gold-based interdigitated electrode IDE, with an alumina substrate and an electrode spacing of approximately 100 μm) to form a sensor. The resulting sensor was placed in a resistance detection device at room temperature. After purging with a C4F7N / CO2 background gas for 30 min, a CO gas concentration of 100 ppm was then purged for a period of time. Once the sensor response stabilized, C4F7N / CO2 gas was reintroduced for recovery. During this process, the sensor resistance changed significantly, exhibiting a resistance change rate of 28.5% (ΔR / R0, where ΔR is the resistance difference before and after purging the target gas, and R0 is the resistance value before purging the target gas), a response time of 45 s, and a recovery time of 55 s. See [link to relevant documentation]. Figure 2 .

[0062] (3) Selectivity test: To verify the specific recognition capability of the composite membrane of the present invention for CO, the sensor prepared based on the composite membrane material of Example 1 was exposed to 100 ppm CO and other decomposition components (such as C2F6, CF4, C3F6) that may coexist under typical fault conditions in the C4F7N / CO2 mixed gas, as well as the background gas (C4F7N / CO2) under the same test conditions. The test results are shown in Table 1.

[0063] Table 1. Response of the sensor in Example 1 to different characteristic gases (100 ppm, room temperature)

[0064]

[0065] As shown in Table 1, the sensor of this invention exhibits a significant resistance change of 28.5% for CO gas, while the response to other potential interfering gases is less than 2%, which is almost negligible. This fully demonstrates that the PES / UiO-66 composite membrane of this invention has excellent selectivity for CO, effectively eliminating interference from other decomposition components and achieving accurate monitoring of CO.

[0066] Comparative Example 1:

[0067] Compared with Example 1, the difference is that polyethersulfone (PES) is replaced with an equal mass of PVDF powder (Mw=534000), and the other steps are the same.

[0068] See Figure 3 The test results showed that Comparative Example 1 had a response value of only 6.8% to 100 ppm CO, with a response time extended to 120 s and a recovery time of 150 s, significantly lower than Example 1 (corresponding performance indicators of 28.5%, 45 s, and 55 s). This difference highlights the importance of polymer substrate selection. The reason for this is that the polar sulfone group (-SO2-) of PES can form a better synergistic effect with the UiO-66 active site and CO molecules, promoting charge transfer; while the strong hydrophobicity and chemical inertness of PVDF hinder the effective adsorption and interfacial interaction of CO molecules.

[0069] Comparative Example 2:

[0070] Compared with Example 1, the difference is that the coupling agent (KH-550) was omitted when preparing the S2 suspension, while the rest of the steps are the same.

[0071] The gas sensor was fabricated and tested using the same method as in Example 1. See [link to example]. Figure 4The response value of Comparative Example 2 decreased to 11.2%, with a response time of 85 s and a recovery time of 100 s, significantly lower than that of Example 1. This indicates that the coupling agent is key to constructing an efficient sensing interface: KH-550 binds to the hydroxyl groups on the surface of UiO-66 through siloxane groups, while simultaneously forming hydrogen bonds with the PES matrix through amino groups, effectively improving the dispersibility of UiO-66 and preventing aggregation. The absence of the coupling agent would lead to the embedding of active sites, directly reducing sensing efficiency.

[0072] Comparative Example 3:

[0073] Compared with Example 1, the difference lies in the adjustment of the composite membrane preparation process, which adopts an in-situ growth method. All other steps are the same, specifically:

[0074] S1: Preparation of UiO-66 precursor solution

[0075] Preparation of zirconium salt solution: Dissolve 0.233 g of zirconium tetrachloride (ZrCl4) in a mixed solvent of 45 mL N,N-dimethylformamide (DMF) and 5 mL ethanol. Stir mechanically at 500 rpm for 30 minutes at 30°C to ensure complete dissolution of ZrCl4 and formation of a homogeneous Zr salt solution. 4+ Precursor solution, for later use.

[0076] Preparation of organic ligand solution: Dissolve 0.166 g of terephthalic acid in a mixed solvent of 45 mL DMF and 5 mL ethanol, and stir at 30 °C for 30 minutes until the terephthalic acid is completely dissolved to obtain the organic ligand solution for later use.

[0077] S2: Preparation of PES / UiO-66 composite membrane by in-situ growth method

[0078] Preparation of porous PES base film: 0.75g of polyethersulfone (PES) was dissolved in 8.1g of DMF solvent and mechanically stirred at 800rpm for 4 hours at 60℃ to form a homogeneous PES casting solution; the casting solution was cast onto a horizontal glass substrate at 35℃ and 40% relative humidity, and after evaporation at room temperature for 10 hours, it was immersed in deionized water for phase inversion for 30 minutes, and finally vacuum dried at 60℃ to obtain a porous PES base film with a thickness of about 100μm for later use.

[0079] Zr 4+ Ion anchoring: The porous PES base film prepared above is completely immersed in the Zr solution prepared in S1. 4+ In the precursor solution, static impregnation and adsorption were performed at room temperature for 2 hours. The adsorption effect of the porous structure of the PES-based membrane was utilized to allow Zr to be absorbed. 4+ Ions are uniformly anchored on the inner walls and surface of the membrane pores.

[0080] In-situ growth of UiO-66 crystals: The PES substrate film treated as described above is removed and quickly rinsed twice with DMF (10 seconds each time) to remove unadsorbed free Zr from the film surface. 4+ Immediately transfer the base film to the organic ligand solution prepared in S1, and then transfer it together into a 100 mL polytetrafluoroethylene-lined reactor. After sealing, place it in an oven and carry out a solvothermal reaction at 130°C for 20 hours to allow UiO-66 crystals to grow in situ in the pores and on the surface of the PES base film.

[0081] Post-treatment of composite membrane: After the reaction is completed, the reaction vessel is removed and cooled to room temperature. The composite membrane is taken out of the solution and washed three times each with DMF and ethanol (soaking for 1 hour each time) to remove unreacted precursors and impurities. Finally, the composite membrane is placed in a vacuum drying oven at 90℃ and dried for 10 hours to obtain the PES / UiO-66 composite membrane prepared by in-situ growth method.

[0082] The gas sensor was fabricated and tested using the same method as in Example 1. See [link to example]. Figure 5 The response value of Comparative Example 3 was 14.5%, with a response time of 70 s and a recovery time of 90 s, which was inferior to that of Example 1. This verifies the superiority of the blending method in Example 1. The reason for this is that the blending method achieves "pre-dispersion" of UiO-66 through mechanical stirring and ultrasound, and combined with phase transformation, it makes the crystal uniformly embedded in the PES framework, ensuring a three-dimensional uniform distribution of active sites; while the in-situ growth method is difficult to control the uniformity of crystals, easily clogging pores and leading to a decrease in sensing efficiency.

[0083] Comparative Example 4:

[0084] Compared with Example 1, the difference lies in adjusting the phase inversion (NIPS) process parameters in S2 and replacing the non-solvent with pure ethanol instead of deionized water; the other steps are the same.

[0085] The gas sensor was fabricated and tested using the same method as in Example 1. See [link to example]. Figure 6 The response value of Comparative Example 4 was 16.1%, with a response time of 65 s and a recovery time of 80 s, which were lower than those of Example 1. This demonstrates the importance of phase transformation conditions: water, as a strongly polar non-solvent, rapidly exchanges with DMF to form high-porosity finger pores, which facilitates gas diffusion; while ethanol exchanges with DMF more slowly, easily forming a dense sponge-like pore structure, which hinders gas contact with active sites. This proves that the use of aqueous phase transformation in this invention is one of the key points for further optimizing the membrane structure.

[0086] Comparative Example 5:

[0087] Compared to Example 1, most of the steps are the same, the difference being the adjustment of the timing of adding UiO-66 powder. Specifically, the coupling agent is mixed with PES first, and then UiO-66 is added. The specific process is as follows: 0.75g of polyethersulfone (PES) and 0.009g of γ-aminopropyltriethoxysilane (KH-550) are co-dispersed in 8.1g of DMF solvent. The mixture is first mechanically stirred at 1100rpm for 1 hour to premix the coupling agent with the polymer chains. Then, 0.15g of UiO-66 powder is added, and the mixture is mechanically stirred at 1100rpm for 2.5 hours (keeping the total stirring time constant at 3.5 hours). The mixture is then sonicated at 45kHz for 50 minutes to form a film-forming solution. Subsequent steps, such as casting (35°C, 40% relative humidity), room temperature evaporation (10 hours), phase inversion in deionized water (30 minutes), and vacuum drying at 60°C, are the same as in Example 1.

[0088] See Figure 7 The test results showed that Comparative Example 5 had a response value of 13.8% to 100ppmCO, a response time of 80s, and a recovery time of 95s, which was significantly lower than that of Example 1 (28.5%, 45s, and 55s). This difference highlights the importance of the order of addition in the blending process: Example 1, through the simultaneous blending of PES, UiO-66, and the coupling agent, enabled KH-550 to bind to both the hydroxyl groups (silyl end) on the surface of UiO-66 and the PES chain (amino end), forming an efficient "molecular bridge" and ensuring a uniform distribution of active sites; while in Comparative Example 5, the coupling agent was mixed with PES first, causing its silyl end to have difficulty binding to UiO-66 due to steric hindrance, resulting in particle agglomeration, weak interfacial bonding, and ultimately deterioration of sensing performance.

[0089] Table 2: Comparison of sensing performance between Example 1 and Comparative Examples 1-4

[0090]

[0091] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. Application of a PES / UiO-66 composite membrane in detecting the characteristic decomposition component CO of C4F7N / CO2 mixed gas as a gas-sensitive material, characterized in that, The PES / UiO-66 composite film is composed of a PES matrix and UiO-66 crystals uniformly dispersed in the PES matrix; The PES / UiO-66 composite membrane was prepared by the following steps: S1. Dissolve zirconium salt and organic ligand in a mixed solvent of DMF and ethanol, and react by heating to generate UiO-66 crystals. After centrifugation, washing and drying, UiO-66 powder is obtained. S2. Disperse UiO-66 powder uniformly in an organic solvent containing polyethersulfone, add a coupling agent to form a homogeneous suspension, pour it onto a flat substrate, and after solvent evaporation and phase inversion treatment, dry or hot press to obtain a PES / UiO-66 composite film. The phase transformation process employs a non-solvent-induced phase separation method, where the non-solvent used is deionized water or a mixed solution of water and ethanol.

2. Use according to claim 1, characterized in that, In S1, the zirconium salt is ZrCl4 or ZrOCl2·8H2O; the organic ligand is terephthalic acid or 2-aminoterephthalic acid; and the volume ratio of DMF to ethanol is 8~10:

1.

3. Use according to claim 1, characterized in that, In S1, the heating reaction temperature is 120~140℃ and the time is 16~24h.

4. Use according to claim 1, characterized in that, In S2, the homogeneous suspension contains 10-15 wt% polyethersulfone, 5-20 wt% UiO-66 powder, and 0.1-0.5 wt% coupling agent.

5. The use according to claim 1, characterized in that, In S2, the coupling agent is γ-aminopropyltriethoxysilane or γ-(2,3-epoxypropoxy)propyltrimethoxysilane.

6. The application according to claim 1, characterized in that, In S2, the solvent evaporates at a temperature of 25~60℃ for 8~12 hours, and the relative humidity is ≤50%.

7. The application according to claim 1, characterized in that, In S2, the thickness of the PES / UiO-66 composite film is 50~150μm.

8. The application according to claim 1, characterized in that, When the PES / UiO-66 composite membrane comes into contact with CO gas as a gas-sensitive material, it can achieve efficient identification and response of CO gas by detecting the change in the resistance value of the gas-sensitive material.

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