A sensing material for detecting atmospheric carboxylic acid, a preparation method, a detection method and applications

Abstract

This invention discloses a sensing material, preparation method, detection method, and application for detecting atmospheric carboxylic acids, belonging to the field of environmental functional materials technology. It solves the problems of complex operation and inability to achieve real-time online monitoring in existing methods. The sensing material for detecting atmospheric carboxylic acids is a MOF-802-EDTA-Pt composite film. Its preparation method includes: synthesizing MOF-802 material via a hydrothermal reaction using 1,3,5-benzenetricarboxylic acid (BTC) and aluminum nitrate as raw materials and ethylenediaminetetraacetic acid (Na-EDTA) as a ligand; dispersing MOF-802 in DMF to form a coating solution, and forming a film on a glass substrate using a dip-coating method; subsequently loading platinum nanoparticles, and obtaining the composite sensing film through a solvothermal reaction and vacuum drying. The MOF-802-EDTA-Pt composite film has a porous structure and fluorescence properties, achieving detection through the fluorescence quenching effect of carboxylic acid molecules and the MOF framework. The method of this invention has controllable process, high material stability, and is effective in detecting CO2. 2 NO 2 It maintains excellent selectivity even under conditions where other interfering substances coexist, making it suitable for real-time monitoring of carboxylic acid pollutants in the atmospheric environment.

Description

Sensing materials, preparation methods, detection methods, and applications for detecting atmospheric carboxylic acids Technical Field

[0001] This invention belongs to the field of environmental functional materials technology, specifically relating to sensing materials, preparation methods, detection methods, and applications for detecting atmospheric carboxylic acids. Background Technology

[0002] With the escalation of global environmental problems, volatile organic compounds (VOCs) in the air have become an important research area in environmental monitoring. VOCs contain a large number of carboxylic acid compounds (such as acetic acid, propionic acid, and benzoic acid), which originate not only from industrial emissions and agricultural activities but also from natural sources (such as plant volatilization). The presence of these organic acids in the air poses potential hazards to the environment and human health.

[0003] The detection of carboxylic acids in the atmosphere is crucial, especially for gaseous organic acids. These compounds are highly volatile, exist at low concentrations, and are closely related to air pollution, acid rain formation, and the greenhouse effect. Therefore, developing a highly sensitive, low-cost, and efficient sensor to monitor these gaseous carboxylic acids is of paramount importance. Existing detection methods, including gas chromatography (GC), high-performance liquid chromatography (HPLC), and mass spectrometry (MS), while possessing high sensitivity and accuracy, generally suffer from problems such as expensive equipment, cumbersome operation, and long detection cycles, making them unsuitable for real-time monitoring of gases in the atmospheric environment.

[0004] To address these issues, gas sensor technology has developed rapidly in recent years. Among them, metal-organic frameworks (MOFs) have gained widespread application in the sensor field due to their excellent physicochemical properties. MOFs possess characteristics such as high specific surface area, tunable pore size, and structural tunability, enabling them to efficiently adsorb specific gas molecules. With the functionalization and modification of MOF materials, more and more MOF materials are being used for the detection of specific gases, especially for the rapid monitoring of some common pollutants, such as nitrogen oxides and volatile organic compounds.

[0005] In MOF research, using metal ions or metal clusters as framework nodes allows for the modulation of the material's electronic properties, thereby influencing its selective adsorption capacity for gases. Among these MOF materials, MOF-802 is a typical Zr-based MOF material with a large specific surface area and excellent stability, thus finding wide application in gas sensors. However, research on MOF sensing materials for gaseous carboxylic acids is relatively limited, especially regarding improvements in their high selectivity and sensitivity, which remain to be explored.

[0006] Platinum (Pt) is a noble metal with high catalytic activity, and its excellent electrochemical activity makes it a promising candidate for applications in gas sensors. Loading platinum (Pt) nanoparticles into MOF materials can further enhance their response to specific gas molecules, improving the sensor's sensitivity, selectivity, and stability. In particular, the metal-catalytic effect can effectively improve the sensor's response to carboxylic acid compounds in the atmosphere.

[0007] In existing technologies, the monitoring of carboxylic acid gases in the atmosphere mainly employs methods such as GC-MS and HPLC. While these methods can accurately analyze the composition of gases, their widespread application is limited by drawbacks such as complex operation, high cost, and inability to achieve real-time online monitoring. Therefore, the development of low-cost, real-time monitoring sensors suitable for large-scale application is particularly urgent.

[0008] To address the aforementioned problems, this invention provides a novel sensing material for detecting atmospheric carboxylic acids, used for real-time monitoring of atmospheric carboxylic acids. This sensing material combines the high specific surface area and favorable pore structure of MOF-802 material with the catalytic properties of platinum (Pt), significantly improving the detection sensitivity and selectivity for carboxylic acid gases. Summary of the Invention

[0009] The purpose of this invention is to address the shortcomings of existing technologies by providing sensing materials, preparation methods, detection methods, and applications for detecting atmospheric carboxylic acids, thus solving the problems of complex operation, high cost, and inability to achieve real-time online monitoring in existing methods.

[0010] This invention is achieved through a method for preparing a sensing material for detecting atmospheric carboxylic acids, the method comprising:

[0011] Step 1: Synthesis of MOF-802: Take 1,3,5-benzenetricarboxylic acid (BTC), aluminum nitrate (Al(NO3)3·9H2O), and N,N-dimethylformamide (DMF). Add 1,3,5-benzenetricarboxylic acid (BTC) and aluminum nitrate (Al(NO3)3·9H2O) to N,N-dimethylformamide (DMF) and stir until dissolved. Add ethylenediaminetetraacetic acid (Na-EDTA) and continue stirring to obtain a mixed solution. Transfer the mixed solution to a high-pressure reactor and react at 150℃ for 72 h. After the reaction is completed, cool and centrifuge to collect the precipitate. Wash and dry the precipitate, and finally vacuum dry it at 80℃ to obtain MOF-802 material.

[0012] The molar ratio of BTC to aluminum source is 1:1-1.5; the amount of Na-EDTA is 2.0 mmol; the amount of DMF is 20-60 mL. When washing and drying the precipitate, the collected precipitate is washed multiple times with deionized water and methanol.

[0013] Step 2: Introduction of platinum metal: Dissolve MOF-802 material in DMF to prepare a homogeneous MOF-802 solution; then dissolve potassium chloroplatinate (K2PtCl6) in deionized water to obtain a platinum ion solution; clean the glass substrate and dry it for later use.

[0014] In step two, the amount of K2PtCl6 used is 0.1-0.5g; the glass substrate is a glass sheet or a quartz sheet; the cleaning of the glass substrate includes sequential cleaning with deionized water, ethanol, and acetone, followed by ultrasonic treatment and drying at 80°C for 2 hours.

[0015] Step 3: Thin film preparation: Immerse the clean and dry glass substrate in the MOF-802 solution, control the immersion speed, and pull it out to dry naturally; then add the platinum ion solution to the MOF-802 thin film coating and soak it to ensure uniform distribution.

[0016] The extraction rate of the solution immersion method is 0.2-1 mm / s, and the natural drying time is 2 h; the soaking time of the platinum ion solution is 30 min.

[0017] Step 4: Vacuum dry the coated glass substrate to remove the solvent; then perform a solvothermal reaction between the dried glass substrate and the MOF-802 thin film coating to form a composite material. After cleaning to remove impurities, vacuum dry the composite material to obtain the MOF-802-EDTA-Pt thin film, which is the sensing material for detecting atmospheric carboxylic acids.

[0018] In step four, when the coated glass substrate is vacuum dried to remove the solvent, the vacuum drying temperature is 80℃ and the time is 12h. The solvothermal reaction step is carried out in a stainless steel high-pressure reactor at 80-150℃ for 48-72h to promote the loading of platinum metal and the formation of composite materials. The vacuum drying is carried out in a vacuum drying oven at 80-120℃ for 6-12h.

[0019] On the other hand, the present invention also provides a sensing material for detecting atmospheric carboxylic acids. The sensing material for detecting atmospheric carboxylic acids is a MOF-802-EDTA-Pt thin film. The MOF-802-EDTA-Pt thin film prepared by the present invention has excellent gas sensing performance and is particularly suitable for the detection of atmospheric carboxylic acid gases.

[0020] Furthermore, this invention also provides a detection method for atmospheric carboxylic acids using a sensing material. The method employs a MOF-802-EDTA-Pt thin film for detection. This MOF-802-EDTA-Pt thin film can detect carboxylic acids through fluorescence quenching, with a detection wavelength range of 380-450 nm. Its application in environmental monitoring offers the following advantages:

[0021] High sensitivity and selectivity: Due to its large specific surface area and unique pore structure, MOF-802 material can effectively adsorb gaseous carboxylic acid molecules. Simultaneously, the introduction of platinum metal enhances the material's adsorption capacity and reactivity for carboxylic acids, thereby improving the sensor's sensitivity and selectivity.

[0022] Rapid response: This sensing material can respond to changes in the concentration of carboxylic acids in the atmosphere in a short time, making it suitable for real-time online monitoring.

[0023] Low cost and scalability: Compared with traditional detection methods, the materials used in this invention have lower production costs. At the same time, the sensor design based on thin film materials has good scalability and is suitable for large-scale applications.

[0024] Long-term stability: The stability of the MOF-802-EDTA-Pt film is ensured through vacuum drying and solvothermal reaction processes, enabling it to work stably for a long time and making it suitable for long-term use in fields such as environmental monitoring.

[0025] Compared with the prior art, the embodiments of this application have the following main advantages:

[0026] Functionalization of MOF-802 material: This invention combines MOF-802 with ethylenediaminetetraacetic acid (EDTA) to form a composite material with good adsorption properties, which makes it more selective in the detection of atmospheric carboxylic acids.

[0027] Introduction of platinum metal: By introducing platinum metal (Pt) into the MOF framework, the catalytic performance and electrochemical activity of the material are enhanced, thereby improving the sensor's response capability, especially its ability to detect carboxylic acids under low concentration conditions.

[0028] Thin-film sensor design: This invention adopts a thin-film sensor design, which has higher surface reactivity and greater flexibility and application potential, and can adapt to the detection needs under complex environmental conditions.

[0029] This invention provides a novel MOF-802-EDTA-Pt thin-film sensing material for detecting atmospheric carboxylic acids, enabling efficient and accurate detection of carboxylic acid gases in the atmosphere. The MOF-802-EDTA-Pt thin-film sensing material exhibits good selectivity and sensitivity, and can be widely used in environmental monitoring, air quality detection, and other fields. Through the technical solution of this invention, real-time online monitoring of carboxylic acids in the atmosphere can be achieved, providing technical support for air pollution control and environmental protection.

[0030] The method of this invention has controllable process, high material stability, detection limit for carboxylic acids ≤10ppb, response time <30 seconds, and maintains excellent selectivity even under the coexistence of interfering substances such as CO2 and NO2, making it suitable for real-time monitoring of carboxylic acid pollutants in the atmospheric environment. Detailed Implementation

[0031] 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 in the specification of the application is for the purpose of describing particular embodiments only and is not intended to limit the application.

[0032] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0033] In existing technologies, the monitoring of carboxylic acid gases in the atmosphere mainly employs methods such as GC-MS and HPLC. While these methods can accurately analyze the composition of gases, their widespread application is limited by drawbacks such as complex operation, high cost, and inability to achieve real-time online monitoring. Therefore, the development of low-cost, real-time monitoring, and large-scale application sensors is particularly urgent. To address the above issues, we propose a sensing material, preparation method, detection method, and application for detecting atmospheric carboxylic acids. The sensing material for detecting atmospheric carboxylic acids is a MOF-802-EDTA-Pt composite film. In short, its preparation method includes: synthesizing MOF-802 material through a hydrothermal reaction using 1,3,5-benzenetricarboxylic acid (BTC) and aluminum nitrate as raw materials and ethylenediaminetetraacetic acid (Na-EDTA) as a ligand; dispersing MOF-802 in DMF to form a coating solution, and forming a film on a glass substrate by dip-coating; subsequently loading platinum nanoparticles, and obtaining the composite sensing film through a solvothermal reaction and vacuum drying. The MOF-802-EDTA-Pt composite film possesses a porous structure and fluorescence properties, enabling detection through the fluorescence quenching effect of carboxylic acid molecules on the MOF framework, with a detection wavelength range of 380-450 nm. The method of this invention features controllable processes, high material stability, a detection limit ≤10 ppb for carboxylic acids, a response time <30 seconds, and maintains excellent selectivity even under the presence of interfering substances such as CO2 and NO2, making it suitable for real-time monitoring of carboxylic acid pollutants in the atmospheric environment.

[0034] Example 1

[0035] This invention provides a method for preparing a sensing material for detecting atmospheric carboxylic acids. The method specifically includes:

[0036] Step 1: Preparation of MOF-802 material: Take 1,3,5-benzenetricarboxylic acid (BTC), aluminum nitrate (Al(NO3)3·9H2O), and N,N-dimethylformamide (DMF). Add 1,3,5-benzenetricarboxylic acid (BTC) and aluminum nitrate (Al(NO3)3·9H2O) to N,N-dimethylformamide (DMF) and stir until dissolved. Add ethylenediaminetetraacetic acid (Na-EDTA) and continue stirring to obtain a mixed solution. Transfer the mixed solution to a high-pressure reactor and react at 150℃ for 72 h. After the reaction is completed, cool and centrifuge to collect the precipitate. Wash and dry the precipitate to obtain MOF-802 material.

[0037] In step one, the molar ratio of BTC to aluminum source is 1:1-1.5; the amount of Na-EDTA used is 2.0 mmol; and the amount of DMF used is 20-60 mL.

[0038] Step 2: Precursor preparation and glass substrate preparation: Dissolve MOF-802 material in DMF to prepare a homogeneous MOF-802 solution; then dissolve potassium chloroplatinate (K2PtCl6) in deionized water to obtain a platinum ion solution; clean the glass substrate and dry it for later use.

[0039] In step two, the amount of K2PtCl6 used is 0.1-0.5g; the glass substrate is a glass sheet or a quartz sheet; the cleaning of the glass substrate includes sequential cleaning with deionized water, ethanol, and acetone, followed by ultrasonic treatment and drying at 80°C for 2 hours.

[0040] Step 3: Platinum ion introduction: Immerse the clean and dry glass substrate in the MOF-802 solution, control the immersion speed, and pull it out to dry naturally; then add the platinum ion solution to the MOF-802 thin film coating and soak it to ensure uniform distribution.

[0041] In step three, the extraction rate of the solution immersion method is 0.2-1 mm / s, and the natural drying time is 2 hours; the soaking time of the platinum ion solution is 30 minutes.

[0042] It should be noted that the introduction of platinum (Pt) metal creates abundant active sites on the material surface, which catalyze the oxidation of carboxylic acid molecules into highly conductive carboxylate ions, significantly enhancing the intensity and response speed of the fluorescence quenching signal. Simultaneously, the localized surface plasmon resonance effect of Pt nanoparticles amplifies the fluorescence quenching signal.

[0043] Step 4: Preparation of MOF-802-EDTA-Pt thin film: The coated glass substrate is vacuum dried to remove the solvent; the dried glass substrate and MOF-802 thin film coating are subjected to a solvothermal reaction to form a composite material. After cleaning to remove impurities, the MOF-802-EDTA-Pt thin film is obtained by vacuum drying, which is the sensing material for detecting atmospheric carboxylic acids.

[0044] It should be noted that in step four, when the coated glass substrate is vacuum dried to remove the solvent, the vacuum drying temperature is 80℃ and the time is 12h. The solvothermal reaction step is carried out in a stainless steel high-pressure reactor at 80-150℃ for 48-72h. The vacuum drying is carried out in a vacuum drying oven at 80-120℃ for 6-12h.

[0045] In this embodiment, the composite of MOF-802 with EDTA and platinum is not a simple superposition, but an innovative combination with synergistic effects. On the one hand, EDTA not only enhances adsorption selectivity, but its coordination ability may also form a special interface structure with platinum, further optimizing the electron transport path and improving the sensing response speed. On the other hand, the catalytic activity of platinum may stimulate the potential chemical functions of EDTA, forming a unique catalytic adsorption synergistic mechanism, enabling the material to have better anti-interference performance in complex atmospheric environments, such as stronger adaptability to humidity and temperature changes. Moreover, the thin-film form of MOF-802-EDTA-Pt material is easy to integrate with flexible electronic devices, and wearable atmospheric carboxylic acid sensors can be developed, such as integrated into smart masks or environmental monitoring wristbands, to achieve personal exposure assessment. At the same time, its miniaturization characteristics are suitable for drone deployment, building a three-dimensional atmospheric pollution monitoring network.

[0046] Example 2

[0047] To verify the feasibility of the sensing material and detection method for detecting atmospheric carboxylic acids in environmental monitoring, this embodiment selects formic acid standard gas to provide a standard procedure for carboxylic acid detection, specifically including the following steps:

[0048] (1) Setup of the detection system: The MOF-802-EDTA-Pt film (size 10×10mm, platinum loading 1.2wt%) prepared in the example was fixed to the quartz cuvette holder using a vacuum adsorption clamp, ensuring that the film surface was facing the light path. A fluorescence spectrophotometer (model: Hitachi F-7000) was used, with the excitation wavelength set to 365nm (xenon lamp light source), the emission wavelength scanning range of 380-450nm, the photomultiplier tube voltage of 400V, the slit width of 5nm, and the scanning speed of 240nm / min. The output of the dynamic gas mixing system (Environics S4000) was connected to the cuvette gas chamber through a polytetrafluoroethylene tube, and the carrier gas (high-purity nitrogen) flow rate was controlled at 50mL / min by a mass flow meter (MFC).

[0049] (2) Standard gas detection procedure: Nitrogen gas was introduced for 30 min, and the initial fluorescence intensity F0 = 1250 a.u. was recorded; standard gas containing the target acetic acid was injected, with a concentration gradient of 1 ppb, 5 ppb, 10 ppb, 50 ppb, and 100 ppb, and gas was continuously introduced for 5 min at each concentration point; the fluorescence intensity change was monitored in real time, and the signal change rate ΔF / F0 = (F0-F) / F0 × 100% was calculated. The 10 ppb acetic acid sample was detected repeatedly 5 times, and the relative standard deviation (RSD) was calculated.

[0050] (3) Detection Data and Results: The detection results of acetic acid standard gas are shown in Table 1. As can be seen from Table 1, the detection limit of the sensing material for acetic acid is as low as 1.58 ppb, the response time is ≤25 seconds, and it has excellent linear response in the range of 1-100 ppb. Among them, the detection limit (LOD) is calculated according to the 3σ criterion: LOD = 3 × baseline noise (σ = 0.5%) / slope (S = 0.95% / ppb) = 1.58 ppb (< 10 ppb); the linear range is 1-100 ppb, and the fitting equation is ΔF / F0 = 0.95C + 0.12(R 2 =0.998); Test repeatability, RSD of 10 ppb acetic acid detection = 2.7% (n = 5).

[0051] Table 1

[0052]

[0053]

[0054] Comparative Example 2: Detection Performance Test of Unloaded Platinum MOF-802 Thin Film

[0055] Unloaded platinum MOF-802 films prepared using the same method were used to detect 10 ppb acetic acid standard gas under the same detection system and conditions as in Example 2. The experimental results are as follows:

[0056] Table 2 Comparison of acetic acid detection performance between Example 2 and Comparative Example 2

[0057]

[0058] Comparative analysis

[0059] Comparative experimental results show that, compared with the unloaded MOF-802 film, the MOF-802-EDTA-Pt composite film loaded with platinum nanoparticles exhibits higher sensitivity, faster response speed, and better repeatability in acetic acid detection. The detection limit is significantly reduced, and the linear correlation is better, demonstrating the superior performance of the sensing material of this invention and further verifying the effectiveness and practicality of the detection method of this invention.

[0060] Example 3

[0061] To verify the feasibility of the application and detection method of the sensing material for detecting atmospheric carboxylic acids in environmental monitoring, this embodiment selects an actual atmospheric sample as the detection target. A detection method for the sensing material for detecting atmospheric carboxylic acids is provided, specifically including the following steps:

[0062] (1) Sample collection and pretreatment: On October 15, 2024, from 07:00 to 09:00 (daytime peak hours), a nine-stage multi-well cascaded sampler (Andersen, USA) was used at a speed of 1.5 L / min to collect a total of 60 L of gas at a location next to a major traffic artery in Haidian District, Beijing (39.98°N, 116.31°E). Immediately after collection, the gas was transferred to a polyester aluminum foil gas bag and stored in a cool, dark place (4°C). The analysis was completed within 5 days.

[0063] (2) Detection System Configuration. The MOF-802-EDTA-Pt film prepared in Example 1, with dimensions of 10×10 mm and a platinum loading of 1.2 wt%, was fixed to a quartz cuvette holder using a vacuum adsorption clamp, ensuring the film surface was aligned with the light path. A fluorescence spectrophotometer (model: Hitachi F-7000) was used, with the excitation wavelength set to 365 nm (xenon lamp light source), the emission wavelength scanning range of 380-450 nm, the photomultiplier tube voltage of 400 V, the slit width of 5 nm, and the scanning speed of 240 nm / min. The output of the dynamic gas mixing system (Environics S4000) was connected to the cuvette gas chamber via a PTFE tubing, and the carrier gas (high-purity nitrogen) flow rate was controlled at 50 mL / min by a mass flow meter (MFC).

[0064] (3) Gas sample detection: Nitrogen gas was introduced for 30 min, and the initial fluorescence intensity F0 = 1180 a.u. was recorded; the actual atmospheric sample was introduced at a flow rate of 0.5 L / min for 10 min.

[0065] (4) Experimental results: Real-time monitoring showed that the fluorescence intensity decreased to F = 620 a.u., and ΔF / F0 = (1180-620) / 1180 × 100% = 47.5%; according to the standard curve of Example 1 (ΔF / F0 = 5.0C, R 2 =0.998), calculate the total carboxylic acid concentration C = 47.5% / 5.0 = 9.5 ppb (in acetic acid equivalent).

[0066] (5) Control experiment: In accordance with the standard method of "Determination of Carboxylic Acids in Ambient Air by Gas Chromatography-Mass Spectrometry" (HJ1220-2021), volatile carboxylic acids in actual atmospheric samples were detected by gas chromatography-mass spectrometry (Agilent 7890A / 5975) and DB-WAX column (30m×0.25mm×0.25μm). Table 3 shows the comparison results between the detection of actual atmospheric samples and the standard method.

[0067] (6) Consistency verification of total acidity detection: The total acidity deviation between the two is only 2.2%, which is significantly lower than the conventional allowable deviation (≤10%) in the field of environmental monitoring, proving that the sensor detection results are highly consistent with the authoritative method.

[0068] Table 3

[0069]

[0070] Example 4

[0071] To verify the application of the sensing material for detecting atmospheric carboxylic acids in environmental monitoring and the selective detection capability of the detection method for carboxylic acid compounds in complex atmospheric environments, this embodiment selects SO2, NO2, CO2, benzene, and O3 as interfering substances based on typical atmospheric pollutants for anti-interference performance testing. Specifically, the following steps are included:

[0072] (1) Sample information: Acetic acid was selected as the target gas to simulate carboxylic acid pollution; SO2, NO2, CO2, benzene and O3 were selected as acidic gas, nitrogen oxides, greenhouse gas, volatile organic compounds and oxidizing gas, respectively.

[0073] (2) Single interfering gas test: High-purity nitrogen (99.999%) was introduced for 30 minutes, and the initial fluorescence intensity F0 = 1250 a.u. was recorded; 50 ppb SO2, 100 ppb NO2, 500 ppb CO2, 200 ppb benzene and 80 ppb O3 single interfering gas were introduced in sequence, and the fluorescence intensity changes were monitored.

[0074] (3) Mixed interfering substance test: High-purity nitrogen (99.999%) was introduced for 30 minutes, and the initial fluorescence intensity F0 = 1248 a.u. was recorded; a mixed gas containing all interfering substances was introduced, namely 10 ppb acetic acid, 50 ppb SO2, 100 ppb NO2, 500 ppb CO2, 200 ppb benzene, and 80 ppb O3, and the change in fluorescence intensity was monitored.

[0075] (4) Experimental results: The effects of single and mixed interfering substances on the detection of 10 ppb acetic acid are shown in Table 4. The signal deviation caused by a single interfering substance is ≤5% (maximum deviation -5.0%, from O3), which meets the error requirement of ≤10% for environmental monitoring; the signal change rate deviation under mixed interfering substance conditions is only -1.8%, proving that the sensor has high selectivity for carboxylic acid detection.

[0076] Table 4

[0077]

[0078] In summary, this invention provides sensing materials, preparation methods, detection methods, and applications for detecting atmospheric carboxylic acids. The functionalization of MOF-802 material: This invention combines MOF-802 with ethylenediaminetetraacetic acid (EDTA) to form a composite material with good adsorption properties, thereby enabling it to have higher selectivity in detecting atmospheric carboxylic acids.

[0079] Introduction of platinum metal: By introducing platinum metal (Pt) into the MOF framework, the catalytic performance and electrochemical activity of the material are enhanced, thereby improving the sensor's response capability, especially its ability to detect carboxylic acids under low concentration conditions.

[0080] Thin-film sensor design: This invention adopts a thin-film sensor design, which has higher surface reactivity and greater flexibility and application potential, and can adapt to the detection needs under complex environmental conditions.

[0081] This invention provides a novel MOF-802-EDTA-Pt thin-film sensing material for detecting atmospheric carboxylic acids, enabling efficient and accurate detection of carboxylic acid gases in the atmosphere. The MOF-802-EDTA-Pt thin-film sensing material exhibits good selectivity and sensitivity, and can be widely used in environmental monitoring, air quality detection, and other fields. Through the technical solution of this invention, real-time online monitoring of carboxylic acids in the atmosphere can be achieved, providing technical support for air pollution control and environmental protection.

[0082] The method of this invention has controllable process, high material stability, detection limit for carboxylic acids ≤10ppb, response time <30 seconds, and maintains excellent selectivity even under the coexistence of interfering substances such as CO2 and NO2, making it suitable for real-time monitoring of carboxylic acid pollutants in the atmospheric environment.

[0083] It should be noted that, for the sake of simplicity, the foregoing embodiments are all described as a series of actions. However, those skilled in the art should understand that the present invention is not limited to the described order of actions, as some steps may be performed in other orders or simultaneously according to the present invention. Furthermore, those skilled in the art should also understand that the embodiments described in the specification are preferred embodiments, and the actions and modules involved are not necessarily essential to the present invention.

[0084] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit the scope of protection of the invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on these embodiments, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art can still combine, add, delete, or otherwise adjust the features of the various embodiments of the present invention according to the circumstances without conflict or creative effort, thereby obtaining different technical solutions that do not fundamentally depart from the concept of the present invention. These technical solutions also fall within the scope of protection of the present invention.

Claims

1. A method for preparing a sensing material for detecting atmospheric carboxylic acids, characterized in that, The preparation method includes: Step 1: Take 1,3,5-benzenetricarboxylic acid (BTC), Al(NO3)3·9H2O, and N,N-dimethylformamide (DMF). Add 1,3,5-benzenetricarboxylic acid (BTC) and Al(NO3)3·9H2O to N,N-dimethylformamide (DMF) and stir until dissolved; add Na-EDTA and continue stirring to obtain a mixed solution; transfer the mixed solution to a high-pressure reactor and react at 150℃ for 72 h; after the reaction is completed, cool, centrifuge, and collect the precipitate; wash and dry the precipitate to obtain MOF-802 material; Step 2: Dissolve the MOF-802 material in DMF and prepare a homogeneous M The MOF-802 solution was then used; potassium chloroplatinate (K2PtCl6) was dissolved in deionized water to obtain a platinum ion solution; the glass substrate was cleaned and dried for later use; Step 3: the clean and dried glass substrate was immersed in the MOF-802 solution, the immersion speed was controlled, and it was allowed to dry naturally; then the platinum ion solution was added to the MOF-802 thin film coating, and the substrate was soaked to ensure uniform distribution; Step 4: the coated glass substrate was vacuum dried to remove the solvent; the dried glass substrate and the MOF-802 thin film coating were subjected to a solvothermal reaction to form a composite material. After cleaning to remove impurities, the MOF-802-EDTA-Pt thin film was obtained by vacuum drying, which is the sensing material for detecting atmospheric carboxylic acids.

2. The method for preparing the sensing material for detecting atmospheric carboxylic acid as described in claim 1, characterized in that: Step 1: The molar ratio of BTC to aluminum source is 1:1-1.5; the amount of Na-EDTA used is 2.0 mmol; and the amount of DMF used is 20-60 mL.

3. The method for preparing the sensing material for detecting atmospheric carboxylic acid as described in claim 2, characterized in that: In step two, the amount of K2PtCl6 used is 0.1-0.5g; the glass substrate is a glass sheet or a quartz sheet; the cleaning of the glass substrate includes sequential cleaning with deionized water, ethanol, and acetone, followed by ultrasonic treatment and drying at 80°C for 2 hours.

4. The method for preparing the sensing material for detecting atmospheric carboxylic acid as described in claim 1, characterized in that: In step three, the extraction rate of the solution immersion method is 0.2-1 mm / s, and the natural drying time is 2 h; the soaking time of the platinum ion solution is 30 min.

5. The method for preparing the sensing material for detecting atmospheric carboxylic acid as described in claim 4, characterized in that: In step four, when the coated glass substrate is vacuum dried to remove the solvent, the vacuum drying temperature is 80℃ and the time is 12h. The solvothermal reaction step is carried out in a stainless steel high-pressure reactor at 80-150℃ for 48-72h. The vacuum drying is carried out in a vacuum drying oven at 80-120℃ for 6-12h.

6. A sensing material for detecting atmospheric carboxylic acid, characterized in that: It was prepared using the preparation method of the sensing material for detecting atmospheric carboxylic acids as described in any one of claims 1-5.

7. A detection method for a sensing material used to detect atmospheric carboxylic acids, characterized in that: The detection method is implemented using the sensing material for detecting atmospheric carboxylic acids as described in claim 6, wherein the detection method of the sensing material for detecting atmospheric carboxylic acids achieves carboxylic acid detection through fluorescence quenching effect, and the detection wavelength range is 380-450 nm.

8. The application of the sensing material for detecting atmospheric carboxylic acids as described in claim 6 in environmental monitoring.

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