Electrochemical sensor based on MXene / MWCNTs-COOH / MOF-808 and application thereof

Abstract

The invention discloses an electrochemical sensor based on MXene / MWCNTs (multi-walled carbon nanotubes)-COOH / MOF-808 and an application of the electrochemical sensor in detection of catechin. The MXene / MWCNTs-COOH / MOF-808 composite material is prepared by taking MWCNTs-COOH as an intercalation layer, taking Ti3AlC2 as an MAX phase, preparing Ti3C2 (MXene) through an HF etching method, preparing MOF-808 through a one-pot hydrothermal method, and successfully loading the MOF-808 onto the MXene material of the MWCNTs-COOH intercalation layer through an acoustochemical method in order to improve the weak conductivity of the MOF-808, thereby obtaining the MXene / MWCNTs-COOH / MOF-808 composite material. And further modifying the electrode with the graphene to prepare the working electrode. MWCNTs-COOH and MXene have good conductivity, and are compounded with MOF-808 with adsorption sites, so that reaction catalysis sites of catechin are provided for the final composite material, and the problems of low electrocatalytic activity and low sensitivity in the CA detection process are solved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electrochemical sensors, and relates to an electrochemical sensor based on MXene / MWCNTs-COOH / MOF-808 and application of the electrochemical sensor in catechin detection. BACKGROUND

[0002] Catechin (CA) is a flavonoid compound with a reducing polyphenol group, which mainly exists in daily food and beverages. CA is also one of natural lipid antioxidants, has anti-cancer and anti-inflammatory properties, can scavenge free radicals generated in the human body, and can be used for treating or preventing human health problems, including cardiovascular diseases, diabetes, inflammation, obesity, hypertension and other chronic diseases. However, excessive intake of catechin can also cause many hazards. Therefore, it is crucial to develop a method for sensitive, accurate and quantitative analysis of catechin.

[0003] Metal-organic frameworks (MOFs) are a kind of hybrid porous materials formed by connecting inorganic units and organic units together through strong bonds (reticular synthesis). MOFs have adjustable pore size, large surface area, rich metal active sites and other excellent characteristics. MOF-808 is one of the most representative Zr-based MOFs, which has larger specific surface area and pore volume, and excellent chemical stability and mechanical properties compared with classic Zr-based MOFs. However, the low conductivity of MOF is still a key factor limiting its application in the field of electrochemical sensing. Therefore, it is usually combined with conductive materials to improve the conductivity of MOF.

[0004] Multi-walled carbon nanotubes have unique molecular structures, which make them have excellent mechanical and physical properties, excellent electrothermal performance and chemical stability, etc. Therefore, they have attracted widespread attention, which makes them also one of the ideal choices for electrochemical sensor materials. However, due to the action of π-π bond and high specific surface energy, the original MWCNTs are prone to aggregation to form clusters. Therefore, MWCNTs are often combined with guest particles or the surface of the side wall substituent is functionalized to enhance the biocompatibility of carbon nanotubes.

[0005] MXene is a new type of two-dimensional (2D) transition metal carbide, carbonitride and nitride, and its chemical formula is M n+1 X n T xwherein M is an early transition metal, X represents nitrogen or carbon, n = 1-4, T represents a surface functional group (for example -OH, -O, -F). Generally, MXene is obtained by selective etching of A layer in a mother phase (MAX), and has a large surface area, excellent electrical conductivity and rich surface groups. The MXene has good hydrophilicity and conductivity, and is one of the excellent candidate materials in the field of electrochemical sensing.

[0006] However, an electrochemical sensor for catechin detection constructed by compounding the above three materials has not been reported. SUMMARY

[0007] The application provides an electrochemical sensor based on MXene / MWCNTs-COOH / MOF-808, which can effectively solve the problems of low electrocatalytic activity and low sensitivity in the catechin detection process.

[0008] The electrochemical sensor is a three-electrode system, which comprises a working electrode, a reference electrode and a counter electrode. The working electrode is a MXene / MWCNTs-COOH / MOF-808 modified glassy carbon electrode, the reference electrode is a silver / silver chloride electrode, and the counter electrode is a platinum electrode. The linear range is 0.5-21.53 µM, and the detection limit (LOD) is 0.048 μM (S / N = 3).

[0009] Preparation of the working electrode in the CA electrochemical sensor of the application 1) Preparation of MXene (Ti3C2T x ) ) Ti3AlC2 was weighed and slowly added to a polytetrafluoroethylene beaker containing HF. After magnetic stirring at a constant temperature of 40 ℃ for 24 h, the supernatant was washed with deionized water until the pH was neutral, and the black powder solid (Ti3C2T x ) was obtained by freeze-drying. Ti3C2T x was added to DMSO, and after magnetic stirring at room temperature and washing with deionized water, it was dispersed in ultrapure water, ultrasonic treated and high-speed centrifuged, and finally freeze-dried to obtain layered MXene nanosheets.

[0010] The amount of Ti3AlC2MAX added to 10 ml of HF is 0.4-0.6 g, and the amount of Ti3C2T x 10 ml of DMSO solution is required for intercalation.

[0011] 2) Preparation of MWCNTs-COOH Carboxylated carbon nanotubes were obtained by mixing 100 mg of multi-walled carbon nanotubes (MWCNTs) with 20 mL of an acid solution prepared by mixing 4.0 mol / L HNO3 and 10.0 mol / L H2SO4 at a volume ratio of 1:3, and then stirring the mixture at room temperature for 20-25 h.

[0012] 3) Preparation of MXene / MWCNTs-COOH MXene and MWCNTs-COOH at a mass ratio of (2-4):1 were separately ultrasonically dispersed in deionized water. Then, the MWCNTs-COOH solution was poured into the MXene solution and ultrasonically treated. After centrifugation, the product was freeze-dried to obtain MXene / MWCNTs-COOH.

[0013] 4) Preparation of MOF-808 ZrCl4 and H3BTC were ultrasonically dissolved in DMF / formic acid solution at a mass ratio of 1:1 and a volume ratio of 1:1. After stirring and ultrasonic treatment at room temperature for 30 min, the solution was transferred to a high-pressure reaction kettle and placed in an oven at 130 ℃ for 24 h. After the reaction kettle was naturally cooled to room temperature, the obtained product was washed with DMF and methanol three times, and then vacuum dried to obtain white powder MOF-808.

[0014] 5) Preparation of MXene / MWCNTs-COOH / MOF-808 The same mass of MOF-808 and MXene / MWCNTs-COOH were weighed and separately ultrasonically dispersed in DMF and ultrapure water. Then, the MOF-808 solution was added to the MXene / MWCNTs-COOH solution and ultrasonically treated. After magnetic stirring at room temperature for 24 h, the final product was washed with deionized water and freeze-dried to obtain MXene / MWCNTs-COOH / MOF-808.

[0015] The electrochemical sensor prepared based on MXene / MWCNTs-COOH / MOF-808 can be used for electrochemical detection of CA in tea. MXene with rich surface functional groups and good conductivity is used as the substrate, and after intercalation by MWCNTs-COOH, the surface area of the material is increased, and the stability of the material is also increased. The successful loading of MOF-808 on MXene / MWCNTs-COOH provides the final composite material with catechin adsorption and catalytic sites. The prepared CA electrochemical sensor has a good linear range: 0.5 ~ 21.53 µM and a low detection limit (0.048 µM). When it is applied to detect catechin in actual samples, the average recovery rate of CA can reach 96.46 % ~ 99.71 %. Experiments show that the sensor has good reproducibility, stability and anti-interference for CA detection. The present application provides an ideal detection method for the detection of CA in tea, and has good application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0016] Figure 1 The cyclic voltammograms (CV) of bare GCE, MOF-808 / GCE, MXene / GCE, MXene / MWCNTs-COOH / GCE and MXene / MWCNTs-COOH / MOF-808 / GCE in 1.0 mM [Fe(CN)6] 3- / 4- and 0.1 M KCl.

[0017] Figure 2 The impedance (EIS) curves of bare GCE, MOF-808 / GCE, MXene / GCE, MXene / MWCNTs-COOH / GCE and MXene / MWCNTs-COOH / MOF-808 / GCE in 5.0 mM [Fe(CN)6] 3- / 4- and 0.1 M KCl.

[0018] Figure 3 The DPV plots of the electrochemical sensor of the present application in 0.1 M PBS buffer at different pH values.

[0019] Figure 4 The CV curve of the electrochemical sensor of the present application in 0.1 M PBS buffer at pH 2.0, detecting CA (1 mM) at different scan rates (20-100 mV / s).

[0020] Figure 5 The DPV detection plots of the electrochemical sensor of the present application in 0.1 M PBS buffer at pH 2.0 for different concentrations of CA.

[0021] Figure 6 is Figure 5 The linear relationship fitting diagram of the peak current and the CA concentration when the DPV detection of different concentrations of CA was carried out in the above-mentioned solution.

[0022] Figure 7 The reproducibility test diagram of the prepared sensor for detecting CA in the 0.1 M PBS buffer solution containing CA (0.5 mM) and having a pH of 2.0 by using five MXene / MWCNTs-COOH / MOF-808 modified electrodes.

[0023] Figure 8 The storage stability test diagram of the modified electrode for detecting 5-HT of the same concentration every day for 8 days in the 0.1 M PBS buffer solution containing CA (0.5 mM) and having a pH of 2.0 by using the modified electrode.

[0024] Figure 9 The anti-interference ability of the sensor was verified by adding 100 µM concentration of various interferents in the 0.1 M PBS buffer solution containing CA (10 µM) and having a pH of 2.0 and detecting the change of the peak current by using the DPV technology.

[0025] Figure 10 is the XRD diagram of the prepared materials MXene, MWCNTs-COOH, MXene / MWCNTs-COOH, MOF-808 and MXene / MWCNTs-COOH / MOF-808. DETAILED DESCRIPTION

[0026] The present application will be clearly and completely described below in combination with the drawings and specific embodiments. EMBODIMENT

[0027] MXene was prepared by a hydrofluoric acid etching method. 1 g of Ti3AlC2 was slowly added to a Teflon beaker containing 20 ml of HF, and then magnetically stirred at a constant temperature of 40 ℃ for 24 h. After that, the supernatant was washed with deionized water until the pH was neutral, and then freeze-dried to obtain a black powder solid (Ti3C2T x ). The Ti3C2T x was added to 10 ml of DMSO and magnetically stirred at room temperature for 24 h. Then, it was immediately washed with deionized water for three times, and then dispersed in 200 ml of ultrapure water. After ultrasonic treatment for 5 h, it was centrifuged at a high speed of 10000 rpm / min, and finally freeze-dried to obtain layered MXene nanosheets.

[0028] Take 0.2 g of MWCNTs into 40 ml mixed solution of 4.0 mol / L nitric acid and 10.0 mol / L sulfuric acid (V 硝酸 / V 硫酸 =1:3), after magnetic stirring at room temperature for 24 h, wash with deionized water, and vacuum dry at 80 ℃ for 12 h to obtain black MWCNTs-COOH.

[0029] Take 1.2 g of MXene and 0.4 g of MWCNTs-COOH respectively and ultrasonically disperse them in deionized water, pour the MWCNTs-COOH solution into the MXene solution and continue to ultrasonic, centrifuge the product and freeze-dry to obtain MXene / MWCNTs-COOH.

[0030] Ultrasonically dissolve 0.1748 g of ZrCl4 and 0.1748 g of H3BTC in 16 ml of DMF / formic acid solution, stir at room temperature for 1 h until the solution is clear, transfer the solution into a 100 ml high-pressure reactor after ultrasonic for 30 min, and place it in an oven at 130 ℃ for 24 h. After the reactor is naturally cooled to room temperature, the obtained product is washed with DMF and methanol three times in turn, and vacuum dried at 60 ℃ for 24 h to obtain white powder solid MOF-808.

[0031] Take 100 mg of MOF-808 and MXene / MWCNTs-COOH respectively, ultrasonically disperse them in DMF and ultrapure water respectively, then add the MOF-808 solution into the MXene / MWCNTs-COOH solution, continue to ultrasonic for 30 min, and then magnetically stir at room temperature for 24 h. Finally, wash with deionized water and freeze-dry to obtain the product MXene / MWCNTs-COOH / MOF-808.

[0032] The XRD patterns of each product are shown in Figure 10 It can be seen that: Figure 10 (1) MXene / MWCNTs-COOH (green curve) Peak superposition: the (002) peak of MXene (~10°) coexists with the (002) peak of MWCNTs-COOH (~26°), indicating that mechanical mixing does not significantly change the crystal structure of the components.

[0033] Change of interlayer spacing: the main peak of MXene slightly shifts to low angle (e.g. 10°→9.5°), indicating that MWCNTs are inserted into the interlayer of MXene, resulting in an increase in interlayer spacing (d value).

[0034] ​Carbon tube dispersibility: The peak intensity of MWCNTs-COOH decreased, which may be due to the two-dimensional structure of MXene inhibiting the aggregation of carbon tubes and improving the dispersibility.

[0035] (2) MXene / MWCNTs-COOH / MOF-808 (red curve) MOF structure retention: The MOF-808 characteristic peaks (such as ~20°, 30°) are still visible, but the intensity is weakened, which may be due to the wrapping of MOF after compounding or the disordering of part of the structure.

[0036] New peak generation: A weak broadening peak appears near ~15°, which may be an amorphous phase or a new composite structure formed by the interface interaction of MXene and MOF.

[0037] MXene peak stability: The MXene (002) peak position does not shift significantly, indicating that its layered structure remains intact in the composite system.

[0038] The above data show that MXene / MWCNTs-COOH / MOF-808 material is successfully synthesized.

[0039] 1 mg of the prepared MXene / MWCNTs-COOH / MOF-808 composite material was uniformly dispersed in 1 ml of DMF to obtain a first dispersion liquid; a GCE was polished to a mirror surface using a 0.05 μm α-Al2O3 polishing powder slurry, then it was placed in ethanol and deionized water for ultrasonic treatment for 5 min and dried in a nitrogen atmosphere, 8 μL of the dispersion liquid was dropped on the polished surface of the GCE, and dried under an infrared lamp to obtain a first working electrode.

[0040] 1 mg of the prepared MXene / MWCNTs-COOH composite material was uniformly dispersed in 1 ml of DMF to obtain a second dispersion liquid; a GCE was polished to a mirror surface using a 0.05 μm α-Al2O3 polishing powder slurry, then it was placed in ethanol and deionized water for ultrasonic treatment for 5 min and dried in a nitrogen atmosphere, 8 μL of the dispersion liquid was dropped on the polished surface of the GCE, and dried under an infrared lamp to obtain a second working electrode.

[0041] 1 mg of the prepared MOF-808 composite material was uniformly dispersed in 1 ml of DMF to obtain a third dispersion liquid; a GCE was polished to a mirror surface using a 0.05 μm α-Al2O3 polishing powder slurry, then it was placed in ethanol and deionized water for ultrasonic treatment for 5 min and dried in a nitrogen atmosphere, 8 μL of the dispersion liquid was dropped on the polished surface of the GCE, and dried under an infrared lamp to obtain a third working electrode.

[0042] 1 mg of the prepared MXene composite material was uniformly dispersed in 1 ml of DMF to obtain the fourth dispersion; the GCE was polished to a mirror surface using a 0.05 μm 𝛼-Al2O3 polishing powder slurry, then placed in ethanol and deionized water for 5 minutes and dried in a nitrogen atmosphere. 8 μL of the dispersion was drop-coated on the polished surface of the GCE and dried under an infrared lamp to obtain the fourth working electrode.

[0043] The GCE was polished to a mirror surface using 0.05 μm 𝛼-Al2O3 polishing powder slurry, and then placed in ethanol and deionized water for 5 min and dried in a nitrogen atmosphere to obtain a bare GCE.

[0044] contrast: The first working electrode, the second working electrode, the third working electrode, the fourth working electrode and the bare GCE were used as working electrodes, respectively, in a solution containing 1.0 mM [Fe(CN)6] 3- / 4- CV tests were performed in 0.1 M KCl solution and 0.1 M KCl solution, respectively. Figure 1 The cyclic voltammetry (CV) curve of the modified electrode is shown in Figure 2. Figure 1 It can be seen that MOF-808 has the worst electrical conductivity, bare GCE has a significant redox peak current, and the anodic peak current of MXene is greater than that of GCE, indicating that MXene itself has good electrical conductivity. MXene / MWCNTs-COOH has a higher redox peak current than MXene. This is because the intercalation of carbon nanotubes increases the interlayer distance and the surface area of ​​the material, which improves the electron transfer ability. MXene / MWCNTs-COOH / MOF-808 has the largest I p , which indicates that the electrochemical probe formed by it has the best electrocatalytic activity and conductivity.

[0045] Figure 2 Five different electrodes were tested in a solution containing 0.1 M KCl and 5.0 mM [Fe(CN)6] 3- / 4- The impedance curve in the buffer solution is shown in the figure. As shown in the figure, with the intercalation and loading of MXene, the electrode modified by MXene / MWCNTs-COOH / MOF-808 has the smallest charge transfer resistance (R ct ), which is consistent with the results of the CV curves, indicating that the electrode modified with the composite material has the largest charge transfer rate, further proving that the MXene / MWCNTs-COOH / MOF-808 electrode has been successfully modified.

[0046] The DPV graphs of the CA electrochemical sensor of the present invention in 0.1 M PBS buffer at different pH values ​​are shown in FIG. Figure 3The different pH values have an influence on the current response and peak potential, and the best current response is obtained at pH = 2.0. The modified electrode has the best selective adsorption for CA at pH = 2.0.

[0047] The CV curves of the electrochemical sensor of the application for detecting CA (1 mM) at different scanning rates (20-100 mV / s) in 0.1 M PBS buffer solution with pH = 2.0 are shown in FIG. 3. Figure 4 As shown in FIG. 3, in 0.1 M PBS buffer solution with pH = 2.0, the current response is enhanced with the increase of the scanning rate. The greater the scanning rate, the better the selective adsorption response of the modified electrode to CA.

[0048] The DPV detection curves of the electrochemical sensor of the application (0.1 M PBS buffer solution with pH = 2.0) for different concentrations of CA are shown in FIG. 4. Figure 5 As can be seen from the figure, the oxidation potential of CA is between 0.30 V and 0.60 V. With the increase of the concentration of CA, the response current on the electrode also increases, and the detection limit is 0.048 μM. The peak current has a good linear relationship with the concentration of CA, as shown in FIG. 5. Figure 6 As shown in FIG. 5, the calibration curve consists of a linear section (0.50-21.53 μM). At a lower analyte concentration, the slope of the linear part of the calibration is high due to a large number of active sites.

[0049] Five glassy carbon electrodes were taken and cleaned to obtain five clean glassy carbon electrodes. The MXene / MWCNTs-COOH / MOF-808 composite material prepared in the example was dropped and coated on the first clean glassy carbon electrode, and dried to obtain a first working electrode; The MXene / MWCNTs-COOH / MOF-808 composite material prepared in the example was dropped and coated on the second clean glassy carbon electrode, and dried to obtain a second working electrode; The MXene / MWCNTs-COOH / MOF-808 composite material prepared in the example was dropped and coated on the third clean glassy carbon electrode three times, and dried after each time to obtain a third working electrode; The MXene / MWCNTs-COOH / MOF-808 composite material prepared in the example was dropped and coated on the fourth clean glassy carbon electrode four times, and dried after each time to obtain a fourth working electrode; The MXene / MWCNTs-COOH / MOF-808 composite material prepared in the example was dropped and coated on the fifth clean glassy carbon electrode five times, and dried after each time to obtain a fifth working electrode; The five working electrodes were used as working electrodes of the electrochemical sensor of the present invention, and the stability tests were carried out in 0.1 M PBS buffer containing 0.5 mM CA and pH 2.0 at the same CA concentration, that is, the I pa ,have to Figure 7 The stability test graph is shown. As can be seen from the graph, the peak current detected by each modified electrode does not vary much, with an RSD of 0.87%. This indicates that the electrochemical sensor based on MXene / MWCNTs-COOH / MOF-808 has good reproducibility.

[0050] The five modified electrodes after stability test were stored for 8 days and then subjected to DPV test respectively. Figure 8 , the peak current can still maintain 99.80% of the initial value, indicating that the electrochemical sensor based on MXene / MWCNTs-COOH / MOF-808 has good stability.

[0051] As attached Figure 9 As shown, in a buffer solution with a CA concentration of 10 μM, interfering substances AA and Ca 2+ , Theophylline, D-fructose, L-arginine, Caffeine, Na + , citric acid, glucose and protocatechuic acid, the concentration of each interfering substance in the buffer solution after adding the interfering substance is 100 μM, and the DPV test is performed using the electrochemical sensor of the present invention. The peak current has almost no change, as shown in FIG. Figure 9 The results showed that the electrochemical sensor based on MXene / MWCNTs-COOH / MOF-808 had good anti-interference ability to CA.

Claims

1. An electrochemical sensor based on MXene / MWCNTs-COOH / MOF-808. This electrochemical sensor is a three-electrode system consisting of a working electrode, a reference electrode, and a counter electrode. The working electrode is a MXene / MWCNTs-COOH / MOF-808-modified glassy carbon electrode, the reference electrode is a silver / silver chloride electrode, and the counter electrode is a platinum electrode. It is characterized by: The preparation method of the working electrode is as follows: 1) Weigh Ti3AlC2 and slowly add a small amount into a polytetrafluoroethylene beaker containing HF. Stir magnetically at a constant temperature of 35-55°C, wash with deionized water until the pH of the supernatant is neutral, and freeze-dry to obtain Ti3C2T x Black powder solid; Ti3C2T x The MXene nanosheets were prepared by adding DMSO, magnetically stirring at room temperature, washing with deionized water, dispersing the MXene nanosheets in ultrapure water, ultrasonicating and centrifuging, and finally freeze-drying. 2) MWCNTs were added to a mixed solution of nitric acid and sulfuric acid, magnetically stirred at room temperature, washed with deionized water, and vacuum dried to obtain black MWCNTs-COOH; 3) MXene and MWCNTs-COOH were ultrasonically dispersed in deionized water, and then the MWCNTs-COOH solution was poured into the MXene solution and ultrasonicated again. The product was centrifuged and freeze-dried to obtain MXene / MWCNTs-COOH. 4) Dissolve ZrCl4 and H3BTC in DMF / formic acid solution by ultrasonication. Stir and ultrasonicate at room temperature for 30-40 min. Transfer the solution to a high-pressure reactor and place it in an oven at 120-140°C for 20-25 h. After the reactor is cooled to room temperature, wash the product with DMF and methanol, and vacuum dry to obtain MOF-808 as a white powdery solid. 5) MOF-808 and MXene / MWCNTs-COOH were ultrasonically dispersed in DMF and ultrapure water, respectively. The MOF-808 solution was then added to the MXene / MWCNTs-COOH solution. The mixture was ultrasonically dispersed and magnetically stirred at room temperature. The mixture was washed with deionized water and freeze-dried to obtain MXene / MWCNTs-COOH / MOF-808. 6) Disperse MXene / MWCNTs-COOH / MOF-808 in DMF and ultrasonically homogenize to obtain a dispersion. Drop the dispersion onto the treated glassy carbon electrode and dry it under an infrared lamp to prepare a working electrode.

2. The electrochemical sensor based on MXene / MWCNTs-COOH / MOF-808 according to claim 1, characterized in that: In step 1), the amount of Ti3AlC2 added to 10ml of HF is 0.4~0.6g, 0.4~0.5g Ti3C2T x 10 ml of DMSO solution is required for intercalation.

3. The electrochemical sensor based on MXene / MWCNTs-COOH / MOF-808 according to claim 1, characterized in that: In step 2), MWCNTs-COOH was prepared by mixing 4.0 mol / L HNO3 and 10.0 mol / L H2SO4 in a volume ratio of 1:3 to form an acid solution. MWCNTs were added to the acid solution at a ratio of 100 mg of MWCNTs to 20 mL of acid solution, and the mixture was vigorously magnetically stirred at room temperature for 20-25 h to obtain MWCNTs-COOH.

4. The electrochemical sensor based on MXene / MWCNTs-COOH / MOF-808 according to claim 1, characterized in that: In step 3), the mass ratio of MXene to MWCNTs-COOH is 2:1~4:

1.

5. The electrochemical sensor based on MXene / MWCNTs-COOH / MOF-808 according to claim 1, characterized in that: In step 4), the mass ratio of ZrCl4 to H3BTC is 1:2 to 2:1, and the volume ratio of DMF to formic acid solution is 1:2 to 2:

1.

6. The electrochemical sensor based on MXene / MWCNTs-COOH / MOF-808 according to claim 1, characterized in that: In step 5), the mass ratio of MOF-808 to MXene / MWCNTs-COOH in the mixed solution is 1:2~2:

1.

7. Use of an electrochemical sensor based on MXene / MWCNTs-COOH / MOF-808 prepared by the method of claim 1 in the detection of catechins.

8. The use of the electrochemical sensor based on MXene / MWCNTs-COOH / MOF-808 in catechin detection according to claim 7, characterized in that: The linear range of the electrochemical sensor for catechin detection is 0.50-21.53 μM, and the detection limit is 0.048 μM.

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