Trace chlorine ion detection method based on electrochemistry-fluorescence synergy and related device

Abstract

The application discloses a trace chlorine ion detection method based on electrochemistry-fluorescence cooperation and a related device, which comprises the following steps: 1) preparing MXene-WO 3‑X mixed dimension heterojunction sensitive substrate; 2) preparing a chlorine ion sensitive fluorescent probe dispersion, based on the chlorine ion sensitive fluorescent probe dispersion and the MXene-WO 3‑X mixed dimension heterojunction sensitive substrate, covering an ion selective membrane on the fluorescent sensitive layer to obtain an electrochemistry-fluorescence cooperation sensing electrode; 3) building a detection system based on the electrochemistry-fluorescence cooperation sensing electrode; 4) using the detection system to quantitatively detect trace-level chlorine ions in water. The method and the related device can realize on-site rapid detection of trace-level chlorine ions in water, and have the characteristics of high sensitivity, fast detection speed, strong anti-interference ability, simple operation, controllable cost and the like.

Description

Technical Field

[0001] This invention belongs to the field of water quality testing technology, and relates to a method and related device for detecting trace chloride ions based on electrochemical-fluorescence synergy. Background Technology

[0002] Chloride ions are common anions in water. Moderate amounts of chloride ions do not pose a significant threat to aquatic ecosystems or human health. However, the long-term accumulation of trace chloride ions can accelerate the corrosion of metal equipment and disrupt the ecological balance of aquatic bodies. Furthermore, excessive trace chloride ions in drinking water can also affect human metabolism. Therefore, achieving accurate detection of trace chloride ions in water is of great practical significance.

[0003] Currently, methods for detecting chloride ions in water are mainly divided into two categories: traditional chemical analysis methods and modern instrumental analysis methods. Traditional chemical analysis methods, such as the Mohr method and mercury chromatography, are simple to operate and inexpensive, but have relatively low sensitivity (typically a detection limit ≥10). -6 mol / L), susceptible to Br - I - S² - Coexisting ions can cause interference, and the cumbersome titration process makes it impossible to meet the needs of trace detection. Modern instrumental analysis methods such as ion chromatography, atomic absorption spectrometry, and fluorescence spectrometry can achieve trace detection, but they have obvious drawbacks: ion chromatography instruments are expensive, operation and maintenance costs are high, and the detection time is long (≥30 minutes), requiring professional operators and making it impossible to achieve rapid on-site detection; atomic absorption spectrometry uses an indirect determination method, the operation steps are cumbersome, it is easily affected by matrix effects, and the detection accuracy is limited; fluorescence spectrometry lacks a high-efficiency chloride ion recognition unit, has weak anti-interference ability, and the sensor system assembly is complex and costly.

[0004] In existing technologies, electrochemical sensing technology has gained widespread attention in the field of trace detection due to its advantages of high sensitivity and fast response. However, the sensitive substrates of traditional electrochemical sensors are mostly single nanomaterials, which suffer from low charge transport efficiency and weak signal response, making it difficult to further improve detection sensitivity. At the same time, single sensing mechanisms (such as electrochemistry or fluorescence only) are easily affected by impurities and temperature in the water, resulting in poor detection stability. In addition, most existing trace chloride ion detection technologies require complex sample pretreatment steps, which are cumbersome and cannot be adapted to on-site real-time detection scenarios.

[0005] Therefore, developing a water trace chloride ion detection technology that is highly sensitive, fast in detection, strong in anti-interference ability, easy to operate, cost-controllable, and can achieve rapid on-site detection has become an urgent technical problem to be solved in the field of water quality testing. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method and related device for the detection of trace chloride ions based on electrochemical-fluorescence synergy. This method and related device can realize the rapid on-site detection of trace chloride ions in water and have the characteristics of high sensitivity, fast detection speed, strong anti-interference ability, simple operation and controllable cost.

[0007] To achieve the above objectives, this invention discloses a trace chloride ion detection method based on electrochemical-fluorescence synergy, comprising: 1) Preparation of MXene-WO 3-X Hybrid-dimensional heterojunction sensitive substrate; 2) Preparation of chloride ion-sensitive fluorescent probe dispersion, based on the chloride ion-sensitive fluorescent probe dispersion and MXene-WO 3-X A fluorescence-sensitive layer is prepared on a hybrid-dimensional heterojunction sensitive substrate, and an ion-selective film is coated on the fluorescence-sensitive layer to obtain an electrochemical-fluorescence synergistic sensing electrode. 3) A detection system was built based on the aforementioned electrochemical-fluorescence synergistic sensing electrode; 4) Quantitative detection of trace chloride ions in water is performed using the aforementioned detection system.

[0008] Furthermore, the specific operation of step 1) is as follows: 11) Monolayer WSe2 was synthesized using atmospheric pressure chemical vapor deposition, followed by oxygen plasma post-treatment for 40-60 s to prepare WO3. 3-X Nanowire / WSe2 heterostructure; 12) MXene nanosheets were prepared by hydrofluoric acid etching. The MXene nanosheets were dispersed in deionized water and ultrasonically dispersed for 30-60 minutes to prepare an MXene dispersion with a concentration of 0.5-1.0 mg / mL. 13) Prepare WO 3-X Nanowire / WSe2 heterostructures were immersed in MXene dispersion and kept at 25-35°C for 12-24 hours. After removal, they were rinsed 3-5 times with deionized water and vacuum dried at 60-80°C for 2-4 hours to obtain MXene-WO. 3-X Hybrid-dimensional heterojunction sensitive substrate.

[0009] Furthermore, the specific steps for preparing the chloride ion-sensitive fluorescent probe are as follows: SiO2 fluorescent nanoparticles were mixed with chloride ion-specific recognition ligands, deionized water was added, and the mixture was ultrasonically dispersed for 10-20 minutes to obtain a fluorescent probe dispersion.

[0010] Furthermore, the mass ratio of SiO2 fluorescent nanoparticles to chloride ion-specific recognition ligands is 10:1 to 15:1.

[0011] Furthermore, the chloride ion-specific recognition ligand is 4-aminobenzo-18-crown-6-ether.

[0012] Furthermore, the fluorescent probe dispersion was drop-coated onto MXene-WO 3-X A fluorescent sensitive layer is formed on the surface of a mixed-dimensional heterojunction sensitive substrate by drop-coating at a rate of 5~10 μL / cm² and allowing it to air dry naturally at room temperature.

[0013] Furthermore, an ion-selective film with a thickness of 5-10 μm is coated on the surface of the fluorescence-sensitive layer to obtain an electrochemical-fluorescence synergistic sensing electrode.

[0014] Furthermore, the ion-selective membrane is prepared by mixing polyvinyl chloride, dibutyl phthalate and chloride ion carrier in a mass ratio of 60:35:5.

[0015] This invention discloses a trace chloride ion detection system based on electrochemical-fluorescence synergy, comprising an electrochemical detection module, a fluorescence detection module, and a data processing module. The electrochemical detection module uses an electrochemical-fluorescence synergistic sensing electrode as the working electrode, a saturated calomel electrode as the reference electrode, and a platinum electrode as the counter electrode. During operation, the working electrode is inserted into the sample to be detected, and the electrochemical detection module and fluorescence detection module are activated to simultaneously acquire changes in electrochemical response current and fluorescence intensity. The data processing module detects the concentration of trace chloride ions based on the acquired changes in electrochemical response current and fluorescence intensity.

[0016] Furthermore, the fluorescence detection module uses a fluorescence spectrometer with an excitation wavelength set to 365 nm and an emission wavelength detection range of 400~600 nm. The detection probe of the fluorescence spectrometer is aligned with the fluorescence-sensitive layer of the working electrode.

[0017] The present invention has the following beneficial effects: In specific operation, the trace chloride ion detection method and related device based on electrochemical-fluorescence synergy described in this invention utilizes the chloride ion-sensitive fluorescent probe dispersion and MXene-WO3. 3-X A fluorescent sensing layer was prepared on a hybrid-dimensional heterojunction sensitive substrate. An ion-selective film was then coated onto this fluorescent sensing layer to obtain an electrochemical-fluorescence synergistic sensing electrode. A detection system was built based on this electrochemical-fluorescence synergistic sensing electrode to quantitatively detect trace amounts of chloride ions in water. The fluorescent sensing layer utilizes the charge transport advantages of the MXene layered structure and WO3... 3-X The high activity of nanowires synergistically amplifies the sensing signal, and combined with the electrochemical-fluorescence synergistic sensing mechanism, it achieves dual signal enhancement, enabling precise detection of trace chloride ions in water. It features high sensitivity, fast detection speed, strong anti-interference ability, simple operation, and controllable cost. Attached Figure Description

[0018] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments of this application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0019] Figure 1 This is a flowchart of the method of the present invention. Detailed Implementation

[0020] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] In the description of this invention, it should be understood that the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0022] It should also be understood that the terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms unless the context clearly indicates otherwise.

[0023] It should also be further understood that the term "and / or" as used in this specification and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes such combinations. For example, A and / or B can represent three cases: A alone, A and B simultaneously, and B alone. Additionally, the character " / " in this invention generally indicates that the preceding and following objects have an "or" relationship.

[0024] It should be understood that although terms such as first, second, third, etc., may be used in the embodiments of the present invention to describe the preset range, these preset ranges should not be limited to these terms. These terms are only used to distinguish the preset ranges from one another. For example, without departing from the scope of the embodiments of the present invention, the first preset range may also be referred to as the second preset range, and similarly, the second preset range may also be referred to as the first preset range.

[0025] Depending on the context, the word "if" as used here can be interpreted as "when," "when," "in response to determination," or "in response to detection." Similarly, depending on the context, the phrase "if determination" or "if detection (of the stated condition or event)" can be interpreted as "when determination," "in response to determination," "when detection (of the stated condition or event)," or "in response to detection (of the stated condition or event)."

[0026] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0027] The accompanying drawings illustrate various structural schematic diagrams according to embodiments disclosed in this invention. These drawings are not to scale, and some details have been enlarged for clarity, and some details may have been omitted. The shapes of the various regions and layers shown in the drawings, as well as their relative sizes and positional relationships, are merely exemplary and may deviate from reality due to manufacturing tolerances or technical limitations. Furthermore, those skilled in the art can design regions / layers with different shapes, sizes, and relative positions as needed.

[0028] The trace chloride ion detection method based on electrochemical-fluorescence synergy described in this invention includes the following steps: 1) Preparation of MXene-WO 3-X Hybrid-dimensional heterojunction sensitive substrate; The specific operation of step 1) is as follows: 11) Monolayer WSe2 was synthesized using atmospheric pressure chemical vapor deposition (AP-CVD), followed by oxygen plasma post-treatment for 40-60 s to prepare WO3. 3-X Nanowire / WSe2 heterostructure; 12) MXene nanosheets were prepared by hydrofluoric acid etching. The MXene nanosheets were dispersed in deionized water and ultrasonically dispersed for 30-60 minutes to prepare an MXene dispersion with a concentration of 0.5-1.0 mg / mL. 13) Prepare WO 3-XNanowire / WSe2 heterostructures were immersed in MXene dispersion and kept at 25-35°C for 12-24 hours. After removal, they were rinsed 3-5 times with deionized water and vacuum dried at 60-80°C for 2-4 hours to obtain MXene-WO. 3-X Hybrid-dimensional heterojunction sensitive substrate.

[0029] This substrate utilizes the layered structure of MXene to accelerate charge transfer, combined with WO 3-X The high activity of nanowires synergistically enhances the intensity and stability of sensor signal response.

[0030] 2) Assemble an electrochemical-fluorescence synergistic sensing system 21) Preparation of chloride ion-sensitive fluorescent probes; SiO2 fluorescent nanoparticles and chloride ion-specific recognition ligands were mixed at a mass ratio of 10:1 to 15:1, deionized water was added, and the mixture was ultrasonically dispersed for 10 to 20 minutes to obtain a fluorescent probe dispersion; wherein the chloride ion-specific recognition ligand was 4-aminobenzo-18-crown-6-ether. SiO2 fluorescent nanoparticles were prepared by microemulsion method and loaded with chloride ion-sensitive fluorescent dyes, which can specifically bind to chloride ions and produce a fluorescence quenching effect. 22) Drop the fluorescent probe dispersion obtained in step 21) onto the MXene-WO prepared in step 1). 3-X A fluorescent sensitive layer is formed on the surface of a hybrid-dimensional heterojunction sensitive substrate by drop-coating at a rate of 5~10 μL / cm² and allowing it to air dry naturally at room temperature. 23) An ion-selective film with a thickness of 5-10 μm is coated on the surface of the fluorescence-sensitive layer to obtain an electrochemical-fluorescence synergistic sensing electrode. The ion-selective film is prepared by mixing polyvinyl chloride, dibutyl phthalate, and a chloride ion support in a mass ratio of 60:35:5. This ion-selective film can effectively block Br. - I - S² - Interference from coexisting ions can improve the selectivity of the sensing system.

[0031] 3) Establish a testing system; 31) Construct an electrochemical detection module: Using the electrochemical-fluorescence synergistic sensing electrode prepared in step 2) as the working electrode, the saturated calomel electrode as the reference electrode, and the platinum electrode as the counter electrode, a three-electrode system is formed. Connect it to an electrochemical workstation and set the detection parameters: the scan rate is 50~100 mV / s, and the detection potential range is 0.2~0.8 V. 32) Constructing a fluorescence detection module: Use a fluorescence spectrometer, set the excitation wavelength to 365 nm, and the emission wavelength detection range to 400~600 nm. Align the detection probe of the fluorescence spectrometer with the fluorescence-sensitive layer of the co-sensing electrode to ensure stable detection signal. 33) Set up a data processing module: Connect the electrochemical workstation and the fluorescence spectrometer to the computer respectively. Through data processing software, realize the synchronous acquisition, analysis and fitting of electrochemical signals (current changes) and fluorescence signals (fluorescence intensity changes) to establish a quantitative relationship model between chloride ion concentration and signal intensity.

[0032] 4) Quantitative detection of trace chloride ions in water; 41) Sample pretreatment: Take the water sample to be tested. No complicated pretreatment is required. Filter it through a 0.22 μm filter membrane to remove suspended impurities and obtain the test sample. 42) Signal acquisition: Insert the co-sensing electrode into the sample to be detected, and simultaneously start the electrochemical detection module and the fluorescence detection module to synchronously acquire the changes in electrochemical response current and fluorescence intensity. The detection time is ≤60 seconds. Chloride ions specifically bind to the fluorescent probe, causing fluorescence intensity quenching. At the same time, chloride ions interact with the ion-selective membrane and the sensitive substrate, causing changes in electrochemical response current. The two signals work together to achieve dual recognition of chloride ions. 43) Quantitative Analysis: The collected signal data is input into the data processing module, and the concentration of chloride ions in the water sample to be tested is calculated through a preset quantitative relationship model; wherein, the quantitative relationship model is established by the following method: configuring a series of different concentrations (10 - ¹²~10 -9 A standard chloride ion solution of mol / L was prepared, and electrochemical and fluorescence signals corresponding to each concentration were collected according to steps 41 to 42). The chloride ion concentration was used as the abscissa, and the synergistic value of the change in electrochemical response current and the fluorescence intensity quenching rate was used as the ordinate. Linear fitting was performed to obtain a quantitative relationship model (R²≥0.998).

[0033] 5) Key parameter limitations; 51) Sensitive substrate: MXene-WO 3-X A hybrid-dimensional heterostructure, in which the concentration of MXene nanosheets is 0.5~1.0 mg / mL, and the oxygen plasma treatment time is 40~60 s, ensures that the substrate has excellent charge transport efficiency and signal enhancement capability; 52) Fluorescent probe: The mass ratio of SiO2 fluorescent nanoparticles to chloride ion specific recognition ligands is 10:1~15:1, and the drop-coating amount is 5~10 μL / cm², to ensure the sensitivity and specificity of the fluorescence signal; 53) Detection conditions: Detection temperature is 20~40℃, pH value is 5.0~8.0, no additional pH adjustment of water samples is required, adaptable to different water environments; detection time is ≤60 seconds, and the detection limit is as low as 10. - ¹² mol / L, linear detection range is 10 - ¹²~10 -9 mol / L; 54) Anti-interference performance: Resistant to 100 times the concentration of Br - I - S² - SO4² - NO3 - It can detect coexisting ions with a detection error of ≤±2% and strong anti-interference ability.

[0034] Example 1 MXene-WO 3-X The fabrication process of the hybrid-dimensional heterojunction sensitive substrate is as follows: 1) Using atmospheric pressure chemical vapor deposition (AP-CVD) with WO3 and Se powder as raw materials, a monolayer WSe2 was synthesized by reacting at 800℃ for 2 hours. The synthesized WSe2 was then placed in an oxygen plasma treatment device with a power of 100 W and a treatment time of 50 s to prepare WO3. 3-x Nanowire / WSe2 heterostructure; 2) Take 1 g of Ti3AlC2 powder, add 20 mL of 40% hydrofluoric acid solution, stir at 25℃ for 24 hours to etch away the Al layer, centrifuge (8000 r / min, 10 min), wash with deionized water until neutral, and vacuum dry (70℃, 3 h) to obtain MXene nanosheets; disperse the MXene nanosheets in deionized water and ultrasonically disperse for 45 min to prepare an MXene dispersion with a concentration of 0.8 mg / mL; 3) Will WO 3-X The nanowire / WSe2 heterostructure was immersed in the above MXene dispersion and kept at 30°C for 18 hours. After removal, it was rinsed four times with deionized water and vacuum dried (70°C for 3 hours) to obtain MXene-WO. 3-x Hybrid-dimensional heterojunction sensitive substrate.

[0035] Example 2 The assembly process of the electrochemical-fluorescence synergistic sensing system is as follows: 1) Preparation of SiO2 fluorescent nanoparticles: H2O, cyclohexane, Tritium X-100, and n-hexanol were mixed in a volume ratio of 10:4.2:1.0:1.0 to prepare a microemulsion; 0.1 mol / L Rhodamine B aqueous solution (chloride ion sensitive fluorescent dye) and 2% chitosan aqueous solution were added to the microemulsion to adjust the pH to 7.0, tetraethyl orthosilicate and ammonia were added, the mixture was magnetically stirred for 30 hours, centrifuged and washed (10000 r / min for 15 minutes), and vacuum dried (60℃ for 4 hours) to obtain SiO2 fluorescent nanoparticles; 2) SiO2 fluorescent nanoparticles and 4-aminobenzo-18-crown-6-ether were mixed at a mass ratio of 12:1, deionized water was added, and the mixture was ultrasonically dispersed for 15 minutes to obtain a fluorescent probe dispersion. 3) The fluorescent probe dispersion was drop-coated onto the surface of the sensitive substrate prepared in Example 1 at a rate of 8 μL / cm², and allowed to air dry at room temperature to form a fluorescent sensitive layer. 4) Take 60 mg of polyvinyl chloride, 35 mg of dibutyl phthalate, and 5 mg of chloride ion carrier, add 10 mL of tetrahydrofuran, stir to dissolve, and obtain an ion-selective membrane solution; coat the solution onto the surface of the fluorescence sensitive layer, evaporate the solvent at room temperature to form an ion-selective membrane with a thickness of 8 μm, and assemble the electrochemical-fluorescence co-sensing electrode.

[0036] Example 3 Construction and quantitative detection of the detection system 1) Constructing a three-electrode system: Using the synergistic sensing electrode prepared in Example 2 as the working electrode, the saturated calomel electrode as the reference electrode, and the platinum electrode as the counter electrode, the system was connected to an electrochemical workstation with a scan rate of 80 mV / s and a detection potential range of 0.2~0.8 V. 2) Set up the fluorescence detection module: Use a fluorescence spectrometer with an excitation wavelength of 365 nm and an emission wavelength detection range of 400~600 nm. Align the detection probe with the fluorescence-sensitive layer of the co-sensing electrode and adjust it until the signal is stable. 3) Set up a data processing module: Connect the electrochemical workstation and fluorescence spectrometer to the computer, use Origin software for data acquisition and analysis, and establish a quantitative relationship model; 4) Establishment of standard curve: Configure concentrations of 10 - ¹² mol / L, 5×10 - ¹² mol / L, 10 - ¹¹ mol / L, 5×10 - ¹¹ mol / L, 10 - ¹ 0 mol / L, 5×10 - ¹ 0mol / L, 10 -9 After filtering, mol / L chloride ion standard solutions were prepared. The synergistic sensing electrode was then inserted into each standard solution, and the changes in electrochemical response current and fluorescence intensity were collected simultaneously. The chloride ion concentration was plotted on the x-axis, and the synergistic value of the change in electrochemical response current and the fluorescence intensity quenching rate was plotted on the y-axis. Linear fitting was performed to obtain the standard curve equation: y = 0.023x + 0.0015, R² = 0.9992. 5) Sample Detection: A water sample from an environmental body was taken, filtered through a 0.22 μm filter membrane, and used as the test sample. The co-sensing electrode was inserted into the test sample, the detection system was started, and signal acquisition was completed within 60 seconds. The signal data was input into the data processing module, and the chloride ion concentration in the water sample was calculated to be 3.2 × 10⁻⁶ using the standard curve equation. - ¹¹ mol / L; 6) Accuracy verification: Parallel analysis of the above water samples was performed using ion chromatography, and the result was 3.1 × 10⁻⁶. - ¹¹ mol / L, the relative error between the detection results of this invention and the detection results of ion chromatography is 3.2%, which meets the detection requirements; 7) Anti-interference verification: Add Br at a concentration of 100 times to the above water sample. - I - S² - SO4² - NO3 - The coexisting ions were detected using the technology of this invention, and the result was 3.3 × 10⁻⁶. - ¹¹ mol / L, with a relative error of 3.1%, indicates that the present invention has good anti-interference ability; 8) Reproducibility verification: The above water samples were tested 10 times repeatedly, and the relative standard deviation (RSD) of the test results was 1.2%, indicating that the reproducibility of the present invention is excellent.

[0037] Example 4 The trace chloride ion detection method based on electrochemical-fluorescence synergy described in this invention includes the following steps: 1) Preparation of MXene-WO 3-X Hybrid-dimensional heterojunction sensitive substrate; The specific operation of step 1) is as follows: 11) Monolayer WSe2 was synthesized using atmospheric pressure chemical vapor deposition (AP-CVD), followed by oxygen plasma post-treatment for 50 s to prepare WO3. 3-X Nanowire / WSe2 heterostructure; 12) MXene nanosheets were prepared by hydrofluoric acid etching. The MXene nanosheets were dispersed in deionized water and ultrasonically dispersed for 50 minutes to prepare an MXene dispersion with a concentration of 0.8 mg / mL. 13) Prepare WO 3-X Nanowire / WSe2 heterostructures were immersed in MXene dispersion and allowed to stand at 30°C for 20 hours. After removal, they were rinsed four times with deionized water and vacuum dried at 70°C for 3 hours to obtain MXene-WO. 3-X Hybrid-dimensional heterojunction sensitive substrate.

[0038] This substrate utilizes the layered structure of MXene to accelerate charge transfer, combined with WO 3-X The high activity of nanowires synergistically enhances the intensity and stability of sensor signal response.

[0039] 2) Assemble an electrochemical-fluorescence synergistic sensing system 21) Preparation of chloride ion-sensitive fluorescent probes; SiO2 fluorescent nanoparticles and a chloride ion-specific recognition ligand were mixed at a mass ratio of 12:1, deionized water was added, and the mixture was ultrasonically dispersed for 12 minutes to obtain a fluorescent probe dispersion; wherein the chloride ion-specific recognition ligand was 4-aminobenzo-18-crown-6-ether. SiO2 fluorescent nanoparticles were prepared by microemulsion method and loaded with chloride ion-sensitive fluorescent dyes, which can specifically bind to chloride ions and produce a fluorescence quenching effect. 22) Drop the fluorescent probe dispersion obtained in step 21) onto the MXene-WO prepared in step 1). 3-X A fluorescent sensitive layer was formed on the surface of a hybrid-dimensional heterojunction sensitive substrate by a drop-coating amount of 8 μL / cm² and allowed to air dry at room temperature. 23) An ion-selective film with a thickness of 8 μm was coated on the surface of the fluorescence-sensitive layer to obtain an electrochemical-fluorescence synergistic sensing electrode. The ion-selective film was prepared by mixing polyvinyl chloride, dibutyl phthalate, and a chloride ion support in a mass ratio of 60:35:5. This ion-selective film can effectively block Br₂. - I - S² - Interference from coexisting ions can improve the selectivity of the sensing system.

[0040] 3) Establish a testing system; 31) Construct an electrochemical detection module: Using the electrochemical-fluorescence synergistic sensing electrode prepared in step 2) as the working electrode, the saturated calomel electrode as the reference electrode, and the platinum electrode as the counter electrode, a three-electrode system is formed. Connect it to an electrochemical workstation and set the detection parameters: the scan rate is 80 mV / s, and the detection potential range is 0.2~0.8 V. 32) Constructing a fluorescence detection module: Use a fluorescence spectrometer, set the excitation wavelength to 365 nm, and the emission wavelength detection range to 400~600 nm. Align the detection probe of the fluorescence spectrometer with the fluorescence-sensitive layer of the co-sensing electrode to ensure stable detection signal. 33) Set up a data processing module: Connect the electrochemical workstation and the fluorescence spectrometer to the computer respectively. Through data processing software, realize the synchronous acquisition, analysis and fitting of electrochemical signals (current changes) and fluorescence signals (fluorescence intensity changes) to establish a quantitative relationship model between chloride ion concentration and signal intensity.

[0041] Example 5 The trace chloride ion detection method based on electrochemical-fluorescence synergy described in this invention includes the following steps: 1) Preparation of MXene-WO 3-X Hybrid-dimensional heterojunction sensitive substrate; The specific operation of step 1) is as follows: 11) Monolayer WSe2 was synthesized using atmospheric pressure chemical vapor deposition (AP-CVD), followed by oxygen plasma post-treatment for 60 s to prepare WO3. 3-X Nanowire / WSe2 heterostructure; 12) MXene nanosheets were prepared by hydrofluoric acid etching. The MXene nanosheets were dispersed in deionized water and ultrasonically dispersed for 60 minutes to prepare an MXene dispersion with a concentration of 1.0 mg / mL. 13) Prepare WO 3-X Nanowire / WSe2 heterostructures were immersed in MXene dispersion and allowed to stand at 35°C for 24 hours. After removal, they were rinsed five times with deionized water and vacuum dried at 80°C for 4 hours to obtain MXene-WO. 3-X Hybrid-dimensional heterojunction sensitive substrate.

[0042] This substrate utilizes the layered structure of MXene to accelerate charge transfer, combined with WO 3-X The high activity of nanowires synergistically enhances the intensity and stability of sensor signal response.

[0043] 2) Assemble an electrochemical-fluorescence synergistic sensing system 21) Preparation of chloride ion-sensitive fluorescent probes; SiO2 fluorescent nanoparticles and a chloride ion-specific recognition ligand were mixed at a mass ratio of 15:1, deionized water was added, and the mixture was ultrasonically dispersed for 20 minutes to obtain a fluorescent probe dispersion; wherein the chloride ion-specific recognition ligand was 4-aminobenzo-18-crown-6-ether. SiO2 fluorescent nanoparticles were prepared by microemulsion method and loaded with chloride ion-sensitive fluorescent dyes, which can specifically bind to chloride ions and produce a fluorescence quenching effect. 22) Drop the fluorescent probe dispersion obtained in step 21) onto the MXene-WO prepared in step 1). 3-X A fluorescent sensitive layer was formed on the surface of a hybrid-dimensional heterojunction sensitive substrate by drop-coating at a rate of 10 μL / cm² and allowing it to air dry at room temperature. 23) An ion-selective film with a thickness of 10 μm was coated on the surface of the fluorescence-sensitive layer to obtain an electrochemical-fluorescence synergistic sensing electrode. The ion-selective film was prepared by mixing polyvinyl chloride, dibutyl phthalate, and a chloride ion support in a mass ratio of 60:35:5. This ion-selective film can effectively block Br₂. - I - S² - Interference from coexisting ions can improve the selectivity of the sensing system.

[0044] 3) Establish a testing system; 31) Construct an electrochemical detection module: Using the electrochemical-fluorescence synergistic sensing electrode prepared in step 2) as the working electrode, the saturated calomel electrode as the reference electrode, and the platinum electrode as the counter electrode, a three-electrode system is formed. Connect it to an electrochemical workstation and set the detection parameters: the scan rate is 100 mV / s, and the detection potential range is 0.2~0.8 V. 32) Constructing a fluorescence detection module: Use a fluorescence spectrometer, set the excitation wavelength to 365 nm, and the emission wavelength detection range to 400~600 nm. Align the detection probe of the fluorescence spectrometer with the fluorescence-sensitive layer of the co-sensing electrode to ensure stable detection signal. 33) Set up a data processing module: Connect the electrochemical workstation and the fluorescence spectrometer to the computer respectively. Through data processing software, realize the synchronous acquisition, analysis and fitting of electrochemical signals (current changes) and fluorescence signals (fluorescence intensity changes) to establish a quantitative relationship model between chloride ion concentration and signal intensity.

[0045] Example 6 The trace chloride ion detection method based on electrochemical-fluorescence synergy described in this invention includes the following steps: 1) Preparation of MXene-WO 3-X Hybrid-dimensional heterojunction sensitive substrate; The specific operation of step 1) is as follows: 11) Monolayer WSe2 was synthesized using atmospheric pressure chemical vapor deposition (AP-CVD), followed by oxygen plasma post-treatment for 40 s to prepare WO3. 3-X Nanowire / WSe2 heterostructure; 12) MXene nanosheets were prepared by hydrofluoric acid etching. The MXene nanosheets were dispersed in deionized water and ultrasonically dispersed for 30 minutes to prepare an MXene dispersion with a concentration of 0.5 mg / mL. 13) Prepare WO 3-X Nanowire / WSe2 heterostructures were immersed in MXene dispersion and allowed to stand at 25°C for 12 hours. After removal, they were rinsed three times with deionized water and vacuum dried at 60°C for 2 hours to obtain MXene-WO. 3-X Hybrid-dimensional heterojunction sensitive substrate.

[0046] This substrate utilizes the layered structure of MXene to accelerate charge transfer, combined with WO 3-X The high activity of nanowires synergistically enhances the intensity and stability of sensor signal response.

[0047] 2) Assemble an electrochemical-fluorescence synergistic sensing system 21) Preparation of chloride ion-sensitive fluorescent probes; SiO2 fluorescent nanoparticles and a chloride ion-specific recognition ligand were mixed at a mass ratio of 10:1, deionized water was added, and the mixture was ultrasonically dispersed for 10 minutes to obtain a fluorescent probe dispersion; wherein the chloride ion-specific recognition ligand was 4-aminobenzo-18-crown-6-ether. SiO2 fluorescent nanoparticles were prepared by microemulsion method and loaded with chloride ion-sensitive fluorescent dyes, which can specifically bind to chloride ions and produce a fluorescence quenching effect. 22) Drop the fluorescent probe dispersion obtained in step 21) onto the MXene-WO prepared in step 1). 3-X A fluorescent sensitive layer was formed on the surface of a hybrid-dimensional heterojunction sensitive substrate by drop-coating at a rate of 5 μL / cm² and allowing it to air dry at room temperature. 23) An ion-selective film with a thickness of 5 μm was coated on the surface of the fluorescence-sensitive layer to obtain an electrochemical-fluorescence synergistic sensing electrode. The ion-selective film was prepared by mixing polyvinyl chloride, dibutyl phthalate, and a chloride ion support in a mass ratio of 60:35:5. This ion-selective film can effectively block Br₂. - I - S² - Interference from coexisting ions can improve the selectivity of the sensing system.

[0048] 3) Establish a testing system; 31) Construct an electrochemical detection module: Using the electrochemical-fluorescence synergistic sensing electrode prepared in step 2) as the working electrode, the saturated calomel electrode as the reference electrode, and the platinum electrode as the counter electrode, a three-electrode system is formed. Connect it to an electrochemical workstation and set the detection parameters: the scan rate is 50 mV / s, and the detection potential range is 0.2~0.8 V. 32) Constructing a fluorescence detection module: Use a fluorescence spectrometer, set the excitation wavelength to 365 nm, and the emission wavelength detection range to 400~600 nm. Align the detection probe of the fluorescence spectrometer with the fluorescence-sensitive layer of the co-sensing electrode to ensure stable detection signal. 33) Set up a data processing module: Connect the electrochemical workstation and the fluorescence spectrometer to the computer respectively. Through data processing software, realize the synchronous acquisition, analysis and fitting of electrochemical signals (current changes) and fluorescence signals (fluorescence intensity changes) to establish a quantitative relationship model between chloride ion concentration and signal intensity.

[0049] This invention has the following characteristics: Using MXene-WO 3-X Using hybrid-dimensional heterojunctions as sensitive substrates, the charge transport advantages of MXene layered structures are utilized in conjunction with WO4. 3-X The high activity of nanowires synergistically amplifies the sensing signal, and combined with the electrochemical-fluorescence synergistic sensing mechanism, achieves dual signal enhancement with a detection limit as low as 10. - ¹² mol / L, far superior to existing ion chromatography methods (detection limit 10). -9 (mol / L) and traditional electrochemical sensors can accurately detect trace amounts of chloride ions in water; Fast detection speed and simple operation: No complicated sample pretreatment is required, only simple filtration is needed for detection. The detection time is ≤60 seconds, realizing the leap from the traditional "hour-level" and "minute-level" detection to "second-level" detection. The operation process is simple, no professional operators are required, and it can be adapted to on-site real-time detection scenarios. Strong anti-interference ability: Through the dual action of ion-selective membrane and chloride ion-specific recognition ligand, it effectively blocks Br. - I - S² - It is less affected by interference from coexisting ions. For coexisting ions at a concentration of 100 times, the detection error is ≤±2%, and the detection stability is good. It is suitable for the detection of complex matrix water bodies (such as industrial wastewater).

[0050] Other embodiments of the invention will readily occur to those skilled in the art upon consideration of the specification and disclosure of the invention. This application is intended to cover any variations, uses, or adaptations of the invention that follow the general principles of the invention and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of the invention are indicated by the following claims.

[0051] It should be understood that the present invention is not limited to the precise structure described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of the invention is limited only by the appended claims.

[0052] The above description is merely a preferred embodiment of the present invention and does not constitute any limitation on the present invention. Any simple modifications, alterations, or equivalent structural changes made to the above embodiments based on the technical essence of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A method for detecting trace chloride ions based on electrochemical-fluorescence synergy, characterized in that, include: 1) Preparation of MXene-WO 3-X Hybrid-dimensional heterojunction sensitive substrate; 2) Preparation of chloride ion-sensitive fluorescent probe dispersion, based on the chloride ion-sensitive fluorescent probe dispersion and MXene-WO 3-X A fluorescence-sensitive layer is prepared on a hybrid-dimensional heterojunction sensitive substrate, and an ion-selective film is coated on the fluorescence-sensitive layer to obtain an electrochemical-fluorescence synergistic sensing electrode. 3) A detection system was built based on the aforementioned electrochemical-fluorescence synergistic sensing electrode; 4) Quantitative detection of trace chloride ions in water is performed using the aforementioned detection system.

2. The trace chloride ion detection method based on electrochemical-fluorescence synergy according to claim 1, characterized in that, The specific operation of step 1) is as follows: 11) Monolayer WSe2 was synthesized using atmospheric pressure chemical vapor deposition, followed by oxygen plasma post-treatment for 40-60 s to prepare WO3. 3-X Nanowire / WSe2 heterostructure; 12) MXene nanosheets were prepared by hydrofluoric acid etching. The MXene nanosheets were dispersed in deionized water and ultrasonically dispersed for 30-60 minutes to prepare an MXene dispersion with a concentration of 0.5-1.0 mg / mL. 13) Prepare WO 3-X Nanowire / WSe2 heterostructures were immersed in MXene dispersion and kept at 25-35°C for 12-24 hours. After removal, they were rinsed 3-5 times with deionized water and vacuum dried at 60-80°C for 2-4 hours to obtain MXene-WO. 3-X Hybrid-dimensional heterojunction sensitive substrate.

3. The trace chloride ion detection method based on electrochemical-fluorescence synergy according to claim 2, characterized in that, The specific steps for preparing a chloride ion-sensitive fluorescent probe are as follows: SiO2 fluorescent nanoparticles were mixed with chloride ion-specific recognition ligands, deionized water was added, and the mixture was ultrasonically dispersed for 10-20 minutes to obtain a fluorescent probe dispersion.

4. The method for detecting trace chloride ions based on electrochemical-fluorescence synergy according to claim 2, characterized in that, The mass ratio of SiO2 fluorescent nanoparticles to chloride ion-specific recognition ligands is 10:1 to 15:

1.

5. The method for detecting trace chloride ions based on electrochemical-fluorescence synergy according to claim 2, characterized in that, The chloride ion-specific recognition ligand is 4-aminobenzo-18-crown-6-ether.

6. The method for detecting trace chloride ions based on electrochemical-fluorescence synergy according to claim 2, characterized in that, The fluorescent probe dispersion was drop-coated onto MXene-WO 3-X A fluorescent sensitive layer is formed on the surface of a mixed-dimensional heterojunction sensitive substrate by drop-coating at a rate of 5~10 μL / cm² and allowing it to air dry naturally at room temperature.

7. The method for detecting trace chloride ions based on electrochemical-fluorescence synergy according to claim 1, characterized in that, An ion-selective film with a thickness of 5-10 μm was coated on the surface of the fluorescence-sensitive layer to obtain an electrochemical-fluorescence synergistic sensing electrode.

8. The method for detecting trace chloride ions based on electrochemical-fluorescence synergy according to claim 7, characterized in that, The ion-selective membrane was prepared by mixing polyvinyl chloride, dibutyl phthalate and chloride ion carrier in a mass ratio of 60:35:

5.

9. A trace chloride ion detection system based on electrochemical-fluorescence synergy, characterized in that, The device includes an electrochemical detection module, a fluorescence detection module, and a data processing module. The electrochemical detection module uses the electrochemical-fluorescence synergistic sensing electrode prepared according to claim 1 as the working electrode, a saturated calomel electrode as the reference electrode, and a platinum electrode as the counter electrode. During operation, the working electrode is inserted into the sample to be detected, and the electrochemical detection module and the fluorescence detection module are activated to simultaneously collect changes in electrochemical response current and fluorescence intensity. The data processing module detects the concentration of trace chloride ions based on the collected changes in electrochemical response current and fluorescence intensity.

10. The trace chloride ion detection system based on electrochemical-fluorescence synergy according to claim 9, characterized in that, The fluorescence detection module uses a fluorescence spectrometer with an excitation wavelength set to 365 nm and an emission wavelength detection range of 400~600 nm. The detection probe of the fluorescence spectrometer is aligned with the fluorescence-sensitive layer of the working electrode.

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