Electrochemical sensor based on co@ceo2-ncnt / ti3c2 composite for high sensitive detection of sulfachloropyridazine

Abstract

This invention discloses a Co@CeO2-NCNT / Ti3C2-based electrochemical sensor for thiodichlorophenol, its preparation method, and its application. The sensor includes a working electrode, an auxiliary electrode, and a reference electrode, wherein the working electrode is a Co@CeO2-NCNT / Ti3C2 modified electrode. In the Co@CeO2-NCNT / Ti3C2 composite material, accordion-shaped Ti3C2 serves as a conductive framework, with Co@CeO2-NCNT uniformly loaded on its surface. Cobalt-doped cerium dioxide nanoparticles are anchored on nitrogen-doped carbon nanotubes, forming a multi-component synergistic structure. The preparation method includes Ti3C2 etching synthesis, Co@CeO2-NCNT preparation, modified electrode preparation, and electrochemical sensor fabrication. This sensor enables rapid detection of thiodichlorophenol in water without complex pretreatment, with a detection limit as low as 2.82 nM, a linear range of 5 nM–9 μM, and a spiked recovery rate of 97.1%–104.4%. It has the advantages of high sensitivity, good selectivity, and low cost, and is suitable for rapid detection of thiodichlorophenol in environmental water samples.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical sensing technology, specifically relating to a thiodichlorophenol electrochemical sensor based on Co@CeO2-NCNT and accordion-shaped Ti3C2 composite material, its preparation method and application, which is suitable for rapid and high-sensitivity detection of trace thiodichlorophenol in water samples. Background Technology

[0002] Thionidol, a highly effective antiparasitic drug and broad-spectrum bactericide, is widely used in livestock farming and agricultural production. However, due to its high chemical stability, thiodichlorophenol tends to persist in aquatic environments and bioaccumulate along the food chain, posing potential risks to ecosystem safety and human health. Therefore, developing a rapid, sensitive, portable, and cost-effective method for the trace detection of thiodichlorophenol has become an urgent technical problem to be solved in the fields of water environment monitoring and food safety.

[0003] Currently, conventional methods for detecting thiodichlorophenol mainly rely on chromatography and ultra-high performance liquid chromatography-tandem mass spectrometry. While these methods offer high detection accuracy and qualitative and quantitative capabilities, they suffer from drawbacks such as expensive equipment, complex operation, long analysis cycles, and reliance on specialized laboratories, making them unsuitable for rapid on-site detection. In contrast, electrochemical sensors, with their advantages of fast response speed, ease of operation, and ease of miniaturization and integration, show broad application prospects in on-site pollutant detection.

[0004] The performance of electrode modification materials directly determines the sensitivity, selectivity, and stability of sensors. Previous studies have shown that rare-earth metal oxides (CeO2) have been extensively studied due to their abundant oxygen vacancies and suitable band structure. However, pure CeO2 or CeO2 doped with a single metal still suffers from low electron transport efficiency. Combining CeO2 with carbon nanotubes can improve conductivity to some extent, but bimetallic-loaded carbon nanotubes are prone to aggregation in practical applications, reducing effective active sites and thus limiting the improvement of detection sensitivity. Two-dimensional MXene material Ti3C2, after being etched with hydrofluoric acid, can form an accordion-like structure with interlayer gaps, exhibiting excellent conductivity and electron transfer capabilities. However, its own catalytic activity is relatively limited, making it difficult to achieve highly sensitive detection of dichlorophenoxylate on its own.

[0005] To address the aforementioned technical challenges, combining metal / metal oxide-modified carbon nanotubes with Ti3C2 can achieve synergistically enhanced catalytic performance. However, existing composite strategies often employ simple physical mixing, resulting in drawbacks such as uneven metal site dispersion, easy entanglement and aggregation of carbon nanotubes, and weak interfacial bonding in composite materials. This makes it difficult to simultaneously achieve synergistic optimization of high specific surface area, good conductivity, and highly dispersed active sites. Therefore, developing a novel nanocomposite electrode material with stable structure, excellent conductivity, abundant and uniformly dispersed catalytic active sites, and constructing an electrochemical sensor based on this material suitable for the detection of thiodichlorophenol, is a key direction for overcoming the current bottleneck in the efficient on-site detection of thiodichlorophenol in water. Summary of the Invention

[0006] This invention aims to address the shortcomings of existing thiodichlorophenol detection technologies and the defects in existing electrochemical sensor electrode modification materials. It provides a method for preparing a Co@CeO2-NCNT / Ti3C2 composite material, which possesses a stable layered support structure, excellent conductivity, and highly dispersed bimetallic catalytic active sites. Simultaneously, it provides a thiodichlorophenol electrochemical sensor based on this material and its construction method. This sensor exhibits advantages such as high sensitivity, wide linear range, good anti-interference ability, and long-term stability. Furthermore, this invention provides an application of this sensor in the detection of thiodichlorophenol in actual water samples, enabling rapid and accurate detection of trace amounts of thiodichlorophenol in environmental water bodies.

[0007] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0008] A method for preparing a Co@CeO2-NCNT / Ti3C2 composite material, wherein the composite material is a composite of nitrogen-doped carbon nanotubes supporting cobalt-doped cerium dioxide nanoparticles and accordion-shaped multilayer titanium carbide, denoted as Co@CeO2-NCNT / Ti3C2, and the preparation steps include:

[0009] (1) Preparation of Co@CeO2-NCNT: Carboxylated multi-walled carbon nanotubes were dispersed in deionized water and ultrasonically treated to form a uniform dispersion; dopamine hydrochloride and tris(hydroxymethyl)aminomethane were added sequentially, and the mixture was stirred at room temperature to allow dopamine to polymerize in situ and coat the surface of the carbon nanotubes; then cobalt nitrate hexahydrate and cerium nitrate hexahydrate were added simultaneously, and the mixture was stirred continuously at room temperature to allow the metal ions to be uniformly loaded through coordination; after centrifugation, washing and drying, the obtained precursor was placed in a tube furnace and pyrolyzed at 800℃ for 3 hours under a high-purity nitrogen atmosphere to obtain the Co@CeO2-NCNT composite material;

[0010] (2) Preparation of accordion-shaped Ti3C2: The Ti3C2 phase was dispersed in hydrofluoric acid and etched by continuous stirring at room temperature for 36 hours. After washing and vacuum drying, accordion-shaped multilayer Ti3C2 with interlayer gaps was obtained.

[0011] (3) Preparation of Co@CeO2-NCNT / Ti3C2 composite material: The Co@CeO2-NCNT obtained in step (1) and the Ti3C2 obtained in step (2) are dispersed in deionized water, and after ultrasonic treatment, equal volumes are mixed and further ultrasonicated to make the two uniformly composited to obtain the target composite material.

[0012] A thiodichlorophenol electrochemical sensor includes a glassy carbon electrode substrate and a composite material modification layer modified on the surface of its working electrode, the composite material modification layer being composed of Co@CeO2-NCNT / Ti3C2 nanocomposite material.

[0013] The preparation method of the above-mentioned thiodichlorophenol electrochemical sensor includes the following steps:

[0014] (1) Pretreatment of glassy carbon electrode: The surface of glassy carbon electrode is polished by alumina powder, ultrasonically cleaned in ethanol and deionized water in sequence, and dried to obtain a clean glassy carbon electrode.

[0015] (2) Preparation of composite material dispersion: Co@CeO2-NCNT and accordion-shaped Ti3C2 were dispersed in deionized water, and ultrasonic treatment was performed to obtain a uniform dispersion. The two were mixed in equal volumes and then ultrasonicated again to obtain Co@CeO2-NCNT / Ti3C2 composite material dispersion.

[0016] (3) Sensor construction: The composite material dispersion was drop-coated onto the surface of the pretreated glassy carbon electrode and dried to obtain an electrochemical sensor for the detection of thiodichlorophenol.

[0017] The above-mentioned electrochemical sensor for the detection of thiodichlorophenol employs a linear scanning voltammetry method. The sensor is immersed in the solution to be tested, and the linear scanning voltammetry curve is recorded. The concentration of thiodichlorophenol in the water sample is determined by calculating the characteristic oxidation peak current value of thiodichlorophenol in combination with the standard curve. This method enables rapid detection of trace amounts of thiodichlorophenol in actual environmental water samples.

[0018] The main innovation of this invention is as follows:

[0019] 1. The Co@CeO2-NCNT / Ti3C2 structure boasts a unique design and superior performance: Cobalt and cerium dioxide are anchored onto nitrogen-doped carbon nanotubes using a polydopamine-assisted method, and then combined with accordion-shaped Ti3C2 obtained by hydrofluoric acid etching via ultrasonic self-assembly. The layered structure of Ti3C2 provides a stable supporting substrate for the carbon nanotubes, effectively solving the problem of easy aggregation of bimetallic carbon nanotubes; at the same time, the Co and Ce bimetals form a synergistic catalytic effect, significantly improving the electron transfer efficiency and catalytic activity of the material, giving the composite material the synergistic advantages of large specific surface area, high conductivity, and abundant active sites.

[0020] 2. Superior Sensor Detection Performance: The sensor constructed based on a Co@CeO2-NCNT / Ti3C2 modified glassy carbon electrode exhibits a linear detection range of 5 nM–9 μM for thiodichlorophenol, with a detection limit as low as 2.82 nM. This sensor utilizes the large specific surface area of ​​the accordion-shaped Ti3C2 electrode to achieve efficient enrichment of thiodichlorophenol. Combined with the bimetallic synergistic catalytic effect of Co@CeO2-NCNT, it achieves highly sensitive and specific detection of thiodichlorophenol, demonstrating superior detection performance compared to existing sensors of the same type.

[0021] 3. Strong sensor stability and environmental adaptability: The relative standard deviation of repeatability for eight consecutive tests with a single electrode is 3.7%, and the relative standard deviation of reproducibility for eight different electrodes is 3.1%; the sensor maintains good detection performance after being stored in a refrigerator for 25 days, demonstrating excellent long-term stability; in the presence of interfering substances such as glucose, sucrose, various phenolic compounds, and common ions, the peak current variation range is within 5%, demonstrating strong anti-interference ability.

[0022] 4. Applicable to real-world water sample detection: This sensor has been successfully applied to the detection of thiodichlorophenol in real-world water samples such as West Lake water, pond water, and tap water. The spiked recovery rate is 97.1%–104.4%, and the detection results show good consistency with ultraviolet spectrophotometry, verifying the accuracy and reliability of the sensor in real-world environmental monitoring.

[0023] 5. The preparation method is simple and easy to scale up: The composite material preparation process of the present invention involves conventional processes such as in-situ polymerization of dopamine, coordination loading of metal ions, high-temperature pyrolysis and ultrasonic self-assembly. The operation steps are simple, the raw materials are all commercial products, no complex and expensive equipment is required, it is suitable for large-scale production, and has good prospects for industrial application. Attached Figure Description

[0024] Figure 1 This is a flowchart of the preparation process for Co@CeO2-NCNT / Ti3C2 / GCE.

[0025] Figure 2Scanning electron microscope (SEM) and transmission electron microscope (TEM) images of accordion-shaped Ti3C2, Co@CeO2-NCNT and Co@CeO2-NCNT / Ti3C2 composite materials, and elemental distribution map (EDS) of the composite materials.

[0026] (A) and (D) are SEM and TEM images of accordion-shaped Ti3C2, respectively, showing that Ti3C2 is composed of smooth ultrathin nanosheets stacked into a layered structure with obvious gaps between the layers; (B) and (E) are SEM and TEM images of Co@CeO2-NCNT, respectively, showing that metal nanoparticles are uniformly distributed on carbon nanotubes, and the material exhibits a certain degree of agglomeration; (C) and (F) are SEM and TEM images of Co@CeO2-NCNT / Ti3C2 composite material, respectively, showing that carbon nanotubes are uniformly coated on the surface of accordion-shaped Ti3C2, forming a stable composite structure; (GN) is the EDS spectrum of Co@CeO2-NCNT / Ti3C2 composite material, showing that Ti, C, N, O, Co and Ce are uniformly distributed in the composite material.

[0027] Figure 3 XRD, XPS, Zeta potential and Raman spectra of Co@CeO2-NCNT, Ti3C2 and Co@CeO2-NCNT / Ti3C2.

[0028] (A) XRD patterns of Co@CeO2-NCNT, Ti3C2, and Co@CeO2-NCNT / Ti3C2 show characteristic peaks of Co and CeO2, with the (002) peak of Ti3C2 in the composite material shifting to a lower angle; (B) XPS full spectrum of Co@CeO2-NCNT / Ti3C2; (CG) High-resolution XPS spectra of C 1s, Ti 2p, Co 2p, Ce 3d, and N 1s of Co@CeO2-NCNT / Ti3C2 show successful loading of Co and Ce and stable Ti3C2 structure; (H) Zeta potential diagrams of Co@CeO2-NCNT, Ti3C2, and the composite material show electrostatic interactions between the two components; (I) Raman spectra of Co@CeO2-NCNT, Ti3C2, and the composite material show the effects of the composite material on the electrostatic interactions between the two components. D / I G The ratio decreased.

[0029] Figure 4 Electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), and a comparison of the detection performance of different modified electrodes for p-thiobischlorophenol are shown for Co@CeO2-NCNT / GCE, Ti3C2 / GCE, and Co@CeO2-NCNT / Ti3C2 / GCE.

[0030] The results show that Co@CeO2-NCNT / Ti3C2 / GCE has the lowest charge transfer resistance and the highest peak current. The oxidation peak current of 5.0 μM thiodichlorophenol is 5.87 times that of Co@CeO2-NCNT / GCE, 24.17 times that of Ti3C2 / GCE, and 34.60 times that of bare GCE.

[0031] Figure 5 The linear response (LSV) and linear relationship of Co@CeO2-NCNT / Ti3C2 / GCE to thiodichlorophenol are presented.

[0032] (A) and (B) show that the concentration of thiodichlorophenol has a good linear relationship with the oxidation peak current in two ranges: 5 nM-1000 nM and 1000 nM-9000 nM, with a detection limit of 2.82 nM.

[0033] Figure 6 The graph shows the test results for sensor repeatability, reproducibility, and anti-interference capability.

[0034] (A) and (B) show that the reproducibility RSD of eight different electrodes is 3.1%; (C) and (D) show that the repeatability RSD of eight consecutive detections with a single electrode is 3.7%; (E) and (F) show that the peak current variation is within 5% under the interference of common ions, sugars and phenolic analogs, indicating good selectivity. Detailed Implementation

[0035] The present invention will be further described in detail below with reference to specific embodiments. The scope of protection of the present invention is not limited to the following embodiments.

[0036] Example 1: Preparation of Co@CeO2-NCNT / Ti3C2 composite material

[0037] (1) Synthesis of Co@CeO2-NCNT: 20 mg of carboxylated multi-walled carbon nanotubes were added to 34 mL of deionized water and ultrasonically dispersed for 30 minutes; 10 mg of dopamine hydrochloride and 34 mg of tris(hydroxymethyl)aminomethane were added sequentially, and the mixture was stirred at room temperature for 30 minutes to allow dopamine to polymerize in situ on the surface of the carbon nanotubes to form a coating layer; at the same time, 23 mg of cobalt nitrate hexahydrate and 34 mg of cerium nitrate hexahydrate were added, and the mixture was stirred continuously at room temperature for 24 hours to allow Co@CeO2-NCNT to form a coating layer. 2+ and Ce 3+ Uniform loading; after the reaction, high-speed centrifugation, washing three times with deionized water and anhydrous ethanol, vacuum drying, and then placing in a tube furnace for pyrolysis at 800℃ for 3 hours under a high-purity nitrogen atmosphere. During this process, the polydopamine layer is transformed into a nitrogen-doped carbon matrix, and cobalt and cerium species are reduced and transformed into highly dispersed Co-CeO2 nanoparticles, finally obtaining the Co@CeO2-NCNT composite material.

[0038] (2) Synthesis of accordion-shaped Ti3C2: Take 1 g of Ti3C2 phase powder, disperse it in 20 mL of hydrofluoric acid, stir at room temperature for 36 hours, selectively etch away the aluminum layer; wash with deionized water and anhydrous ethanol alternately 3-5 times to remove residual hydrofluoric acid; place the washed precipitate in a vacuum drying oven at 60℃ and dry for 12 hours to obtain accordion-shaped multilayer Ti3C2 MXene.

[0039] (3) Synthesis of Co@CeO2-NCNT / Ti3C2 composite material: Take 2 mg of Co@CeO2-NCNT prepared in step (1) and 2 mg of Ti3C2 prepared in step (2), add 1 mL of deionized water respectively, and sonicate for 1 hour to obtain a uniform dispersion; take 100 μL of Co@CeO2-NCNT dispersion and 100 μL of Ti3C2 dispersion and mix them, continue to sonicate for 1 hour to fully composite the two materials and obtain Co@CeO2-NCNT / Ti3C2 composite dispersion.

[0040] Example 2 Construction of a thiodichlorophenol electrochemical sensor

[0041] (1) Pretreatment of glassy carbon electrode: Take glassy carbon electrode and polish its surface to mirror finish with 0.3 μm Al2O3 powder to remove surface oxide layer and adsorbed impurities; after polishing, place the electrode in ethanol and deionized water in sequence and ultrasonically clean for 5 minutes each to remove residual polishing powder; after cleaning, dry the electrode surface with infrared lamp for later use.

[0042] (2) Preparation of modified electrode: 6 μL of the Co@CeO2-NCNT / Ti3C2 composite material dispersion prepared in Example 1 was taken by micropipette and uniformly dropped onto the surface of the pretreated glassy carbon electrode. The electrode was dried under an infrared lamp until there were no liquid droplets on the surface and the modified film was dense and uniform, thus obtaining the Co@CeO2-NCNT / Ti3C2 modified electrode.

[0043] Example 3 Performance testing of a thiodichlorophenol electrochemical sensor

[0044] (1) Comparison of electrochemical performance and detection performance of different modified electrodes for p-thiodichlorophenol

[0045] Electrochemical impedance spectroscopy (EIS) was performed at 5 mM [Fe(CN)6] 3- / 4-The process was carried out in solution; Ti3C2 / GCE, Co@CeO2-NCNT / GCE, and Co@CeO2-NCNT / Ti3C2 / GCE were immersed in the above solution, and the Nyquist plots of each electrode were recorded. The charge transfer resistance was fitted by the equivalent circuit model. At the same time, Ti3C2 / GCE, Co@CeO2-NCNT / GCE, Co@CeO2-NCNT / Ti3C2 / GCE, and bare GCE were immersed in 0.1 M PBS buffer solution (pH=7.0) containing 5.0 μM thiodichlorophenol, and the CV curves were recorded, and the oxidation peak current value of thiodichlorophenol was recorded.

[0046] Detection results: Compared with Ti3C2 / GCE and Co@CeO2-NCNT / GCE, the Co@CeO2-NCNT / Ti3C2 / GCE composite electrode showed a significantly reduced charge transfer resistance, more symmetrical and sharper redox peaks, and an oxidation peak current of 16.64 μA for thiodichlorophenol, which is much higher than other modified electrodes. This indicates that the composite material has excellent electron transfer ability and catalytic activity, making it suitable for the detection of thiodichlorophenol.

[0047] (2) Linear range and detection limit detection

[0048] Linear sweep voltammetry (LSV) was used to detect thiodichlorophenol in 0.1 M PBS buffer solution (pH=7.0) containing 5 nM, 20 nM, 50 nM, 100 nM, 600 nM, 1000 nM, 4000 nM, 6000 nM, 8000 nM, and 9000 nM. The characteristic oxidation peak current values ​​of thiodichlorophenol were recorded. A standard curve was fitted with thiodichlorophenol concentration as the x-axis and oxidation peak current as the y-axis, and the limit of detection was calculated according to the formula LOD=3×SD / δ (δ is the slope of the standard curve, and SD is the standard deviation of the intercept).

[0049] Detection results: The concentration of thiodichlorophenol showed a good linear relationship in the ranges of 5 nM-1000 nM and 1000 nM-9000 nM, with a detection limit as low as 2.82 nM, indicating that the sensor has extremely high detection sensitivity.

[0050] (5) Repeatability and reproducibility testing

[0051] Repeatability: The same sensor was immersed in 0.1 M PBS solution of 5.0 μM thiodichlorophenol (pH=7.0) and measured 8 times consecutively. The oxidation peak current value was recorded and the relative standard deviation (RSD) was calculated.

[0052] Reproducibility: Eight Co@CeO2-NCNT / Ti3C2 modified sensors from the same batch were prepared and immersed in 0.1 M PBS solution (pH 7.0) containing 5 μM thiodichlorophenol. The oxidation peak current was measured under the same conditions, and the relative standard deviation (RSD) was calculated.

[0053] Test results: The RSD of the repeatability test was 3.7%, and the RSD of the reproducibility test was 3.1%, both within 5%; indicating that the sensor has good process stability and the test results are reliable.

[0054] (6) Anti-interference capability test

[0055] Using 5.0 μM thiodichlorophenol in 0.1 M PBS solution (pH=7.0) as the test solution, glucose (Glu), sucrose (Suc), CaCl2, KCl, and Na2SO4 were added at 20 times the concentration, and 2-chloro-4-nitrophenol (CNP), 2,4-dichlorophenol (2,4-DCP), 4-chlorophenol (CP), resorcinol (Res), 3-nitrophenol (3-NP), 2-nitrophenol (2-NP), and chloramphenicol (CAP) were added at 5 times the concentration as interfering agents. The sensor was immersed in the solutions containing different interfering agents, and the oxidation peak current value of thiodichlorophenol was determined by linear scanning voltammetry, and the relative standard deviation (RSD) of the current value was calculated.

[0056] Test results: After adding various interfering substances, the RSD of the current value was within 5%, indicating that the sensor has good selectivity for thiodichlorophenol and is not affected by common inorganic ions, sugars and other phenolic compounds.

[0057] (7) Actual sample testing

[0058] West Lake water, Huamei Pond water, and tap water were selected as actual test samples. The water samples were directly tested after filtration. The sensor was immersed in the actual water samples to determine the content of thiodichlorophenol (which was not detected in the initial water samples). The standard addition method was used to add thiodichlorophenol standard solutions of different concentrations to the water samples, and the thiodichlorophenol content of the spiked samples was determined. The spiked recovery rate and relative standard deviation (RSD) were calculated, and the results were verified by ultraviolet spectrophotometry (detection wavelength 315 nm).

[0059] Detection results: The sensor's spiked recovery rate for thiodichlorophenol ranged from 97.1% to 104.4%, showing good consistency with the results obtained by ultraviolet spectrophotometry, with a relative standard deviation (RSD) of 0.3% to 2.4%. This indicates that the sensor is accurate and reliable, and suitable for the detection of thiodichlorophenol in actual environmental water samples.

[0060] Table 1. Comparison of results of Co@CeO2-NCNT / Ti3C2 / GCE sensor and ultraviolet spectrophotometry in detecting thiodichlorophenol in actual water samples

Claims

1. A thiodichlorophenol electrochemical sensor based on Co@CeO2-NCNT / Ti3C2, characterized in that, The device includes a working electrode, an auxiliary electrode, and a reference electrode. The working electrode is a Co@CeO2-NCNT / Ti3C2 modified electrode. The Co@CeO2-NCNT / Ti3C2 modified electrode is composed of a glassy carbon electrode and a Co@CeO2-NCNT / Ti3C2 composite material modified on the surface of the glassy carbon electrode. The Co@CeO2-NCNT / Ti3C2 composite material includes an accordion-like layered structure of Ti3C2 and Co@CeO2-NCNT loaded on the Ti3C2. The Co@CeO2-NCNT is a composite structure formed by cobalt-doped cerium dioxide nanoparticles anchored on nitrogen-doped carbon nanotubes.

2. The thiodichlorophenol electrochemical sensor based on Co@CeO2-NCNT / Ti3C2 as described in claim 1, characterized in that, The Ti3C2 is an accordion-shaped multilayer structure formed by hydrofluoric acid etching. In the Co@CeO2-NCNT, cobalt and cerium dioxide are uniformly distributed in the form of nanoparticles on the surface of nitrogen-doped carbon nanotubes. The nitrogen-doped carbon nanotubes are formed by in-situ polymerization of polydopamine to coat carbon nanotubes and then pyrolysis at high temperature.

3. The thiodichlorophenol electrochemical sensor based on Co@CeO2-NCNT / Ti3C2 as described in claim 1 or 2, characterized in that, The auxiliary electrode is a platinum wire electrode, and the reference electrode is an Ag / AgCl electrode.

4. A method for preparing a thiodichlorophenol electrochemical sensor based on Co@CeO2-NCNT / Ti3C2 as described in any one of claims 1-3, characterized in that, Includes the following steps: (1) Synthesis of Co@CeO2-NCNT composite material: Carboxylated multi-walled carbon nanotubes were dispersed in deionized water and ultrasonically treated for 30 min to form a uniform dispersion; Dopamine hydrochloride and tris(hydroxymethyl)aminomethane were added sequentially, and the mixture was stirred continuously at room temperature for 30 min to allow polydopamine to polymerize in situ and coat the surface of carbon nanotubes. Then, cobalt nitrate hexahydrate and cerium nitrate hexahydrate precursors were added, and the mixture was stirred continuously at room temperature for 24 h to achieve uniform loading of metal ions through coordination. After the reaction was completed, the precursors were centrifuged, washed, and dried. The resulting precursors were then pyrolyzed at 800 °C for 3 h under a nitrogen atmosphere to obtain the Co@CeO2-NCNT composite material. (2) Synthesis of accordion-shaped Ti3C2: Ti3C2 phase was dispersed in hydrofluoric acid and etched by continuous stirring at room temperature for 36 h; the product was washed multiple times with deionized water and ethanol to remove excess hydrofluoric acid, and the resulting precipitate was vacuum dried at 60 °C for 12 h to obtain multilayer accordion-shaped Ti3C2. (3) Preparation of Co@CeO2-NCNT / Ti3C2 modified electrode: Co@CeO2-NCNT obtained in step (1) and Ti3C2 obtained in step (2) were dispersed in deionized water and ultrasonically treated for 1 h to obtain Co@CeO2-NCNT dispersion and Ti3C2 dispersion; the two dispersions were mixed and ultrasonically treated to obtain a uniform Co@CeO2-NCNT / Ti3C2 composite dispersion; the glassy carbon electrode was polished with Al2O3 powder and then ultrasonically cleaned and dried in ethanol and deionized water in sequence; the composite dispersion was drop-coated onto the surface of the dried glassy carbon electrode and dried under an infrared lamp to obtain Co@CeO2-NCNT / Ti3C2 modified electrode; (4) Construction of electrochemical sensor: Using the Co@CeO2-NCNT / Ti3C2 modified electrode obtained in step (3) as the working electrode, a three-electrode working system was constructed by combining the auxiliary electrode and the reference electrode to obtain the thiodichlorophenol electrochemical sensor based on Co@CeO2-NCNT / Ti3C2.

5. The method for preparing the thiodichlorophenol electrochemical sensor based on Co@CeO2-NCNT / Ti3C2 according to claim 4, characterized in that, In step (1), the mass-to-volume ratio of carboxylated multi-walled carbon nanotubes to deionized water was 20 mg:34 mL, and the ultrasonic treatment time was 30 min; the amount of dopamine hydrochloride added was 10 mg, the amount of tris(hydroxymethyl)aminomethane added was 34 mg, and the stirring time at room temperature was 30 min; the amount of cobalt nitrate hexahydrate added was 23 mg, the amount of cerium nitrate hexahydrate added was 34 mg, and the reaction time at room temperature was 24 h; the high-temperature pyrolysis temperature was 800℃, the pyrolysis time was 3 h, and the pyrolysis atmosphere was high-purity nitrogen; In step (2), the mass-to-volume ratio of Ti3C2 phase to hydrofluoric acid was 1 g:20 mL, the etching time at room temperature was 36 h, the vacuum drying temperature was 60℃, and the drying time was 12 h; In step (3), the mass-to-volume ratio of Co@CeO2-NCNT and Ti3C2 dispersed in deionized water was 2 mg:1 mL, the ultrasonic treatment time was 1 h, and the mixed volume of the two dispersions was 100 mL. The drop volume of the composite dispersion on the glassy carbon electrode surface is 6 μL.

6. The method for preparing the thiodichlorophenol electrochemical sensor based on Co@CeO2-NCNT / Ti3C2 according to claim 4, characterized in that, In step (1), the high-temperature pyrolysis process is as follows: the temperature is raised to 700℃-900℃ at a heating rate of 5℃ / min under a high-purity nitrogen atmosphere, and held for 2 h-4 h, preferably raised to 800℃ and held for 3 h.

7. The method for preparing the thiodichlorophenol electrochemical sensor based on Co@CeO2-NCNT / Ti3C2 according to any one of claims 4-6, characterized in that, In step (3), the pretreatment process is as follows: the glassy carbon electrode is polished with 0.3 μm Al2O3 powder, then ultrasonically cleaned in ethanol and deionized water for 5 min each, and the cleaned glassy carbon electrode is dried under an infrared lamp to obtain the pretreated glassy carbon electrode.

8. The method for preparing the thiodichlorophenol electrochemical sensor based on Co@CeO2-NCNT / Ti3C2 according to any one of claims 4-6, characterized in that, In step (3): during the preparation of the Co@CeO2-NCNT dispersion and the Ti3C2 dispersion, the mass-volume ratio of Co@CeO2-NCNT and Ti3C2 to deionized water is 2 mg:1 mL, and the ultrasonic treatment time is 1 h. 100 μL of each dispersion is mixed and further ultrasonically treated until a uniform composite material is formed. 6 μL of the obtained composite dispersion is drop-coated onto the surface of the pretreated glassy carbon electrode and dried under an infrared lamp until there are no droplets on the surface and the modified film is dense and uniform.

9. The application of a thiodichlorophenol electrochemical sensor based on Co@CeO2-NCNT / Ti3C2 constructed as described in any one of claims 1-3, or a thiodichlorophenol electrochemical sensor based on Co@CeO2-NCNT / Ti3C2 constructed as prepared by any one of claims 4-8, in the detection of thiodichlorophenol, characterized in that, The sensor has a linear detection range of 5 nM to 9 μM for thiodichlorophenol and a detection limit of 2.82 nM.

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