A molecularly imprinted modified electrode for detecting trifluoroacetic acid in water, its preparation method and application

Abstract

This invention discloses a molecularly imprinted modified electrode for detecting trifluoroacetic acid in water, its preparation method, and its application. An integrated composite sensing interface is constructed, comprising an enrichment layer, a recognition layer, and a conductive layer, wherein a monolayer Ti3C2T is used. x A three-dimensional conductive network is constructed as the conductive layer, significantly enhancing the electron transfer rate. A molecularly imprinted polymer is used as the conversion layer; its pre-designed specific recognition cavity accurately captures target molecules and converts the specific binding behavior of trifluoroacetic acid into a detectable electrochemical signal. UiO-66-F4 is used as the enrichment layer; leveraging the fluoride-loving interactions between fluorine atoms, trifluoroacetic acid molecules in the water sample are efficiently enriched at the electrode interface, significantly reducing the detection limit to as low as 6.94 ng / L. This molecularly imprinted modified electrode exhibits good selectivity and anti-interference capabilities, along with good repeatability, reducing the detection cost per sample and enabling sensitive and rapid detection of trifluoroacetic acid under complex water conditions.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical detection and sensing technology, and specifically relates to a molecularly imprinted modified electrode for detecting trifluoroacetic acid in water, its preparation method, and its application. Background Technology

[0002] Per- and polyfluoroalkyl substances (PFAS) comprise thousands of synthetic fluorinated compounds. These substances have wide applications, strong environmental persistence, and bioaccumulation potential, and are ubiquitous in global water systems. As long-chain PFAS (such as perfluorooctanoic acid) are gradually phased out under regulatory pressure, ultra-short-chain PFAS such as trifluoroacetic acid (TFA) now dominate the concentration of PFAS in the environment. Unlike hydrophobic long-chain PFAS, which mainly adsorb onto sediments, TFA's acidity and hydrophilicity facilitate rapid leaching, migration, and accumulation in aquatic ecosystems. However, due to its high carbon-fluorine bond dissociation energy, TFA is difficult to degrade naturally. Studies have found that the concentration of TFA in various environmental media is continuously increasing, and in some areas, the concentration of TFA in drinking water has approached or exceeded the total PFAS limit (0.5 μg / L) stipulated in the draft EU Drinking Water Directive.

[0003] Current research has demonstrated that trifluoroacetic acid (TFA) has adverse effects on human health and the environment. Therefore, developing portable, on-site detection methods capable of selectively distinguishing TFA from other interfering substances in complex aquatic matrices is crucial for assessing exposure risks and guiding remediation strategies.

[0004] Currently, the detection and analysis of trifluoroacetic acid mainly relies on liquid chromatography / gas chromatography or fluorine nuclear magnetic resonance spectroscopy. However, these techniques are expensive and require specialized laboratories and trained technicians. Existing methods for trifluoroacetic acid detection also include ultra-high performance liquid chromatography-tandem mass spectrometry, spectrophotometry, and ion-exchange liquid chromatography-tandem mass spectrometry. While effective, these methods are often susceptible to interference and are time-consuming and costly. Therefore, there is an urgent need to develop a simpler, faster, more sensitive, and selective detection method.

[0005] Molecularly imprinted electrodes exhibit high selectivity. By modifying imprinted polymers, they can accurately measure target ions in minute quantities, while also being low in cost and highly practical.

[0006] Emerging sensing strategies (such as colorimetry and fluorescence sensing) show great potential for on-site detection of trifluoroacetic acid, but existing research mostly focuses on sensing gaseous trifluoroacetic acid. Therefore, there is an urgent need to develop a rapid, portable, user-friendly, and low-cost detection method for trifluoroacetic acid in natural water bodies, capable of continuous monitoring. In this context, electrochemical sensing technology presents a promising alternative. Among various electrochemical sensing methods, pulsed electrochemical techniques (such as differential pulse voltammetry and square wave voltammetry) have been widely used in pollutant detection due to their excellent sensitivity and rapid analytical capabilities.

[0007] Due to the excellent stability of the carbon-fluorine bonds in trifluoroacetic acid (TCA), it exhibits significant electrochemical inertness at conventional operating potentials, making it impossible to directly generate detectable signals using traditional voltammetry methods (such as differential pulse voltammetry and square wave voltammetry). Therefore, developing new strategies to effectively overcome this inertia and achieve highly sensitive detection is of paramount importance. Furthermore, the complex composition of water in natural environments presents another significant challenge to achieving high selectivity for TCA detection. To simultaneously address the electrochemical inertness problem and the selectivity challenge in complex matrices, this invention provides a molecularly imprinted modified electrode for detecting TCA in water, its preparation method, and its application. Summary of the Invention

[0008] To address the problems existing in the background technology, the present invention aims to provide a molecularly imprinted modified electrode for detecting trifluoroacetic acid in water, its preparation method, and its application. The present invention constructs an integrated composite sensing interface (enrichment layer-recognition layer-conductive layer). This interface utilizes a fluorinated metal-organic framework (UiO-66-F4) to efficiently enrich trifluoroacetic acid molecules through fluoride-loving interactions between fluorine atoms; it utilizes an introduced molecularly imprinted polymer (MIP) to provide precise complementary spatial recognition sites, achieving specific capture and signal conversion of trifluoroacetic acid; and it utilizes a highly conductive monolayer Ti3C2T… x Constructing a rapid electron conduction network significantly enhances the sensor's sensitivity. This multi-level synergistic design effectively overcomes the electrochemical inertness and environmental interference issues of trifluoroacetic acid molecules, significantly reducing the detection limit.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] The first aspect of the present invention provides a method for preparing a molecularly imprinted modified electrode for detecting trifluoroacetic acid in water, comprising the following steps:

[0011] Synthesis of S1 and UiO-66-F4:

[0012] Tetrafluoroterephthalic acid (TFBDC) and zirconium nitrate tetrahydrate (Zr(NO3)4) were dissolved in a water / glacial acetic acid mixture and subjected to reflux reaction. The reaction product was successively soaked in anhydrous methanol and anhydrous dichloromethane, and then dried under vacuum to obtain UiO-66-F4.

[0013] S2, Molecularly Imprinted Composite Material UiO-66-F4 / MIP@Ti3C2T x Synthesis:

[0014] Trifluoroacetic acid and methacrylic acid were dissolved in acetonitrile for pre-assembly; UiO-66-F4 and monolayer Ti3C2T were added to the system. x Azobisisobutyronitrile (AIBN) and ethylene glycol dimethacrylate (EDMA) were polymerized under nitrogen gas. After centrifugation, the mixture was washed with a methanol / glacial acetic acid mixture to remove template molecules, and then dried to obtain the molecularly imprinted composite material UiO-66-F4 / MIP@Ti3C2T. x ;

[0015] S3, UiO-66-F4 / MIP@Ti3C2T x Preparation of molecularly imprinted modified electrodes: The molecularly imprinted composite material UiO-66-F4 / MIP@Ti3C2T was used. x Dissolved in an ultrapure water / ethanol mixture, ultrasonically mixed, and the mixture was drop-coated onto the electrode surface to obtain UiO-66-F4 / MIP@Ti3C2T. x Molecularly imprinted modified electrodes.

[0016] Preferably, in step S1, the ratio of tetrafluoroterephthalic acid (TFBDC) to zirconium nitrate tetrahydrate (Zr(NO3)4) is 0.65~0.70g:1.30~1.40g.

[0017] Preferably, in step S1, the volume ratio of water to glacial acetic acid in the water / glacial acetic acid mixture is 3~4:2.

[0018] Preferably, in step S1, the reflux reaction temperature is 105~115℃ and the reaction time is 24~25h.

[0019] Preferably, in step S1, the anhydrous methanol soaking time is 70-75 hours, and the anhydrous dichloromethane soaking time is 72-75 hours; the vacuum drying temperature is 115-125°C, and the drying time is 24-25 hours.

[0020] Preferably, in step S2, the trifluoroacetic acid, methacrylic acid, acetonitrile, UiO-66-F4, and monolayer Ti3C2T are... xThe dosage ratio of azobisisobutyronitrile (AIBN) and ethylene glycol dimethacrylate (EDMA) is 1.0~1.1 mmol: 4.0~4.2 mmol: 40~42 mL: 290~310 mg: 290~310 mg: 60~65 mg: 6.0~6.2 mmol.

[0021] Preferably, in step S2, the pre-assembly temperature is room temperature and the time is 12-13 hours; the polymerization reaction temperature is 63-67°C and the reaction time is 12-13 hours.

[0022] Preferably, in step S2, the nitrogen gas introduction time is 25-35 min; the volume ratio of methanol to glacial acetic acid in the methanol / glacial acetic acid mixture is 6:1.

[0023] Preferably, in step S3, the volume ratio of water to ethanol in the water / ethanol mixed solvent is 1~3:1, and the ultrasonic mixing time is 2~3 hours.

[0024] Preferably, the amount of the mixture to be dropped is 20~25μL.

[0025] A second aspect of the present invention provides a molecularly imprinted modified electrode prepared by the above-described preparation method.

[0026] A third aspect of the present invention provides the application of the above-described molecularly imprinted modified electrode in the detection of trifluoroacetic acid in water.

[0027] The present invention has the following beneficial effects:

[0028] (1) This invention provides a molecularly imprinted modified electrode for detecting trifluoroacetic acid in water, and constructs an integrated composite sensing interface based on molecularly imprinted composite materials (including a fluorinated metal-organic framework enrichment layer, a molecularly imprinted polymer recognition layer, and a monolayer Ti3C2T). x (Conductive layer), in which a highly conductive monolayer Ti3C2T is used. x As a conductive layer, a three-dimensional conductive network is constructed, which significantly improves the electron transfer rate. A molecularly imprinted polymer (MIP) is used as the recognition layer; its pre-designed specific recognition cavities can accurately capture target molecules and convert the specific binding behavior of trifluoroacetic acid into a detectable electrochemical signal. A fluorinated metal-organic framework (UiO-66-F4) is used as the enrichment layer; leveraging the fluorophilic interactions between fluorine atoms, trifluoroacetic acid molecules in the water sample are efficiently enriched at the electrode interface, significantly reducing its detection limit. Ultimately, highly selective and sensitive on-site quantitative detection of trifluoroacetic acid in environmental water samples is achieved, with a detection limit as low as 6.94 ng / L. This solves the bottleneck problems of insufficient sensitivity, poor selectivity, reliance on large precision instruments, and inability to be used for portable on-site detection in existing technologies.

[0029] (2) The molecularly imprinted modified electrode provided by the present invention has good selectivity and anti-interference ability, as well as good repeatability, which reduces the detection cost of a single sample and enables sensitive and rapid detection of trifluoroacetic acid under complex water conditions. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 SEM images of the materials prepared in Example 1: (a) Molecularly imprinted polymer (MIP); (b) UiO-66-F4; (c) Monolayer Ti3C2T x (d) Molecularly imprinted composite material UiO-66-F4 / MIP@Ti3C2T x ;

[0032] Figure 2 For molecularly imprinted composite material UiO-66-F4 / MIP@Ti3C2T x EDS plot;

[0033] Figure 3 For: (a) UiO-66-F4, UiO-66-F4@Ti3C2T x (a) FT-IR spectra of MIP and UiO-66; (b) UiO-66-F4, Ti3C2T x and UiO-66-F4@Ti3C2T x (c) X-ray photoelectron spectra of fluorinated metal-organic framework (UiO-66-F4) and unfluorinated metal-organic framework (UiO-66);

[0034] Figure 4 For: (a) Different materials (UiO-66, UiO-66-F4, Ti3C2T) in 0.1M PBS x UiO-66-F4@Ti3C2T x (a) EIS Nyquist plot of the corresponding electrode; (b) UiO-66-F4@Ti3C2T x (c) Charge density difference plot; (d) Different materials (UiO-66, UiO-66-F4, UiO-66-F4@Ti3C2T) in 0.5mM potassium ferricyanide solution. x UiO-66-F4@Ti3C2T x(d) Tafel slope results for the corresponding electrodes; x Results of the charge density difference on the upper probe;

[0035] Figure 5 For: (a) UiO-66-F4 / MIP@Ti3C2T x (a) Graph showing the change in response current of the molecularly imprinted modified electrode after incubation in trifluoroacetic acid solutions of different concentrations; (b) Graph showing the fitting curve of current response to trifluoroacetic acid concentration;

[0036] Figure 6 UiO-66-F4 / MIP@Ti3C2T x Selectivity detection results of trifluoroacetic acid by molecularly imprinted modified electrode;

[0037] Figure 7 UiO-66-F4 / MIP@Ti3C2T x The stability test results of the molecularly imprinted modified electrode for the detection of trifluoroacetic acid are shown in the figure. Detailed Implementation

[0038] In the following description, specific details such as particular system architectures and techniques are set forth for illustrative purposes and not for limitation, in order to provide a thorough understanding of the embodiments of the invention. However, those skilled in the art will understand that the invention can be implemented in other embodiments without these specific details. In other instances, detailed descriptions of well-known systems, apparatuses, circuits, and methods are omitted so as not to obscure the description of the invention with unnecessary detail.

[0039] Example 1

[0040] A method for preparing a molecularly imprinted modified electrode for detecting trifluoroacetic acid in water includes the following steps:

[0041] (1) Monolayer Ti3C2T x Preparation of;

[0042] Ti3AlC2 was etched at 35°C for 24 hours using a volume ratio of concentrated hydrochloric acid: ultrapure water: hydrofluoric acid = 6:3:1. The bottom precipitate was collected and washed by multiple centrifugations to bring the pH of the precipitate to a value greater than 6. An equal weight of anhydrous lithium chloride was added for intercalation for 14 hours. The mixture was then centrifuged until the bottom precipitate swelled, and the collected supernatant was the monolayer Ti3C2. x ;

[0043] (2) Synthesis of UiO-66-F4:

[0044] 0.69 g of tetrafluoroterephthalic acid (TFBDC) and 1.354 g of zirconium nitrate tetrahydrate (Zr(NO3)4) were dissolved in 50 mL of a water / glacial acetic acid mixture (volume ratio 3:2). The mixture was refluxed at 110 °C for 24 h. The reaction product was then soaked in anhydrous methanol for 72 h (the solvent was changed every 24 h), followed by treatment with anhydrous dichloromethane for 72 h. Finally, the product was vacuum dried at 120 °C for 24 h to obtain a white powder, namely UiO-66-F4.

[0045] (3) Molecularly imprinted composite material UiO-66-F4 / MIP@Ti3C2T x Synthesis:

[0046] 1.0 mmol trifluoroacetic acid and 4.0 mmol methacrylic acid were dissolved in 40 mL acetonitrile and pre-assembled for 12 h; 300 mg UiO-66-F4 and 300 mg monolayer Ti3C2T were added to the system. x 62 mg of azobisisobutyronitrile and 6.0 mmol of ethylene glycol dimethacrylate were mixed, and nitrogen gas was purged into the solution for 30 min to remove oxygen. The solution was then polymerized in a 65 °C water bath for 12 h. The precipitate was collected by centrifugation, and the template molecules were removed by shaking with a methanol / glacial acetic acid mixture (6:1, v / v). After drying, a blackish-gray powder was obtained, which is the molecularly imprinted composite material UiO-66-F4 / MIP@Ti3C2T. x ;

[0047] (4) UiO-66-F4 / MIP@Ti3C2T x Preparation of molecularly imprinted modified electrodes:

[0048] The molecularly imprinted composite material UiO-66-F4 / MIP@Ti3C2T x Dissolved in an ultrapure water / ethanol mixture (3:1, v / v), and ultrasonically mixed for 2 h to obtain a mixture. Take 20 μL of the mixture and drop it onto the electrode surface to obtain UiO-66-F4 / MIP@Ti3C2T. x Molecularly imprinted modified electrodes.

[0049] Electrochemical testing conditions: The electrolyte solution consisted of a mixture of 0.1M potassium chloride, 5mM potassium ferrocyanide, and 0.1M phosphate-buffered saline (PBS) at pH 7. Before testing, the electrolyte solution was purged with nitrogen for 15 minutes to eliminate the influence of dissolved oxygen. For environmental water samples, pretreatment included 0.22μm filtration followed by solid-phase extraction, with standard addition calibration using spiking concentrations of 100-1000 ng / L to address matrix effects. In differential pulse voltammetry (DPV) testing, the potential window was set to 0V to 0.4V. Electrochemical impedance spectroscopy (EIS) was performed on a CHI660e electrochemical workstation, with a frequency range of 0.1Hz to 500kHz. Linear sweep voltammetry (LSV) and Tafel analysis were performed within a potential window of -0.8V to 0.8V, using the Tafel slope to compare the catalytic rates of the materials.

[0050] 1. Material Characterization

[0051] (1) Morphological structure characterization

[0052] Figure 1 (a) shows that the molecularly imprinted polymer (MIP) consists of uniform spherical particles (approximately 150 nm in diameter) with clearly defined molecular cavities; Figure 1 (b) shows that the UiO-66-F4 monomer particles are a characteristic nanostructure composed of stacked porous particles, which form an open framework that facilitates the diffusion of analytes; Figure 1 (c) Display of a single layer of Ti3C2T x The original two-dimensional layered morphology of nanosheets; Figure 1 (d) shows the molecularly imprinted composite material UiO-66-F4 / MIP@Ti3C2T x The morphology of the high-density UiO-66-F4 and MIP particles is uniformly inserted into Ti3C2T. x Within the layer, a dense hybrid structure is formed, and Ti3C2T x The surface still retains a clear layered structure, indicating that Ti3C2T in the molecularly imprinted composite material... x Its shape was not damaged.

[0053] (2) EDS characterization

[0054] Figure 2 For molecularly imprinted composite material UiO-66-F4 / MIP@Ti3C2T x The EDS plot, by Figure 2 The results clearly show that Ti3C2T represents x The elemental mapping of Ti and the elemental mappings of Zr and F representing UiO-66-F4 demonstrate that UiO-66-F4 (fluorinated metal-organic framework) is uniformly distributed in the monolayer Ti3C2T. xThe surface.

[0055] (3) Infrared spectroscopy characterization

[0056] Depend on Figure 3 (a) Results of judging the molecularly imprinted composite material UiO-66-F4 / MIP@Ti3C2T x Successfully synthesized; by Figure 3 (b) Result judgment UiO-66-F4@Ti3C2T x Successfully synthesized; Figure 3 (c) shows the X-ray photoelectron spectra of the fluorinated metal-organic framework (UiO-66-F4) and the unfluorinated metal-organic framework (UiO-66). The fluorination success can be determined by the F element peak in the spectrum.

[0057] 2. Electrochemical performance

[0058] Figure 4 (a) The results show that the charge transfer resistance (R) of UiO-66 and UiO-66-F4 is... ct The R values ​​are 457.9Ω and 238.2Ω respectively, for UiO-66-F4. ct The value is significantly lower, which is related to its unique band structure characteristics. Furthermore, Ti3C2T x The combination with UiO-66-F4 enables R ct The Ω was significantly reduced, down to 148.8 Ω, indicating that UiO-66-F4@Ti3C2T x Its conductivity has been improved.

[0059] To elucidate the charge transfer mechanism at the interface, this invention also performed Bader charge analysis, the results of which are shown below. Figure 4 (b). Figure 4 (b) The results obtained from Ti3C2T x The net electron transfer to UiO-66-F4 is 8.11e. - This charge redistribution establishes an interfacial electric field, thereby promoting charge transfer between components.

[0060] The electrode sensitivity was further quantified using Tafel slope analysis, and the results are shown below. Figure 4 (c).

[0061] Depend on Figure 4 (c) The results show that UiO-66, UiO-66-F4, and UiO-66-F4@Ti3C2T x and UiO-66-F4 / MIP@Ti3C2T xThe Tafel slopes are 973.76, 805.61, 125.91, and 203.12 mV / dec, respectively. It is worth noting that UiO-66-F4@Ti3C2T x Heterogeneous structures exhibit the highest sensitivity, and this enhanced dynamic behavior is directly related to the interfacial electronic structure.

[0062] Figure 4 (d) The charge density difference analysis results show that [Fe(CN)6] 3- / 4- Redox probes preferentially adsorb on UiO-66-F4@Ti3C2T x Ti3C2T in the material x Analysis of the titanium atoms in the composition revealed a net charge transfer of 2.85 e from Ti atoms to N atoms. - This indicates that the probe facilitated electron acceptance. Therefore, UiO-66-F4@Ti3C2T x The significant improvement in electrode sensitivity is attributed to the accelerated interfacial charge transfer process, which is achieved by the unique electronic coupling within this heterostructure architecture.

[0063] 3. Analytical performance and linearity of the electrode for trifluoroacetic acid.

[0064] UiO-66-F4 / MIP@Ti3C2T x Molecularly imprinted modified electrodes were placed in trifluoroacetic acid solutions of different concentration gradients (0 μM ~ 13 mM), incubated, and the changes in current response were detected. The test results are as follows: Figure 5 As shown in (a).

[0065] Depend on Figure 5 (a) The results show that the response current gradually decreases with increasing trifluoroacetic acid concentration. This may be because more trifluoroacetic acid binds to sites on the molecularly imprinted polymer, blocking the redox reaction of the potassium ferrocyanide / potassium ferrocyanide probe on the electrode surface. The results indicate that UiO-66-F4 / MIP@Ti3C2T x Molecularly imprinted modified electrodes at 10 -4 ~10 -8 Linearity exists within the range.

[0066] Plotting the current response against the corresponding trifluoroacetic acid concentration gradients at different trifluoroacetic acid concentrations yields linear fitting curves, as shown in the figure. Figure 5 As shown in (b).

[0067] Figure 5 (b) The fitting results show that the response current has a good linear relationship with the concentration of trifluoroacetic acid, R 2 =0.993. The above-mentioned good linear performance can be attributed to the following reasons: (1) using a single layer of Ti3C2Tx (2) The fluorinated metal-organic framework effectively enriches trifluoroacetic acid as an enrichment layer, thus improving the detection accuracy; (3) The molecularly imprinted polymer selectively binds trifluoroacetic acid molecules, thereby improving the sensitivity of electrode detection.

[0068] 4. Electrode selectivity for trifluoroacetic acid

[0069] Ten times the concentration of trifluoroacetic acid, acetic acid, pentafluoropropionic acid, heptafluorobutyric acid, perfluorooctanoic acid, and a mixed solution containing all substances and trifluoroacetic acid were added to the solution. The peak current difference before and after the addition of the interfering substances was measured. The results are shown in [Figure number missing]. Figure 6 .

[0070] Depend on Figure 6 The results show that the presence of other interfering substances does not cause large fluctuations before and after the peak current. The good selectivity of the electrode proves that the molecularly imprinted composite material UiO-66-F4 / MIP@Ti3C2T synthesized in this invention is effective. x It exhibits good selectivity for trifluoroacetic acid.

[0071] 5. Stability testing

[0072] Depend on Figure 7 The results show that by using three sets of parallel electrodes in four tests with three-day intervals to detect trifluoroacetic acid, the difference in the electrode response current was small even after 12 days of storage, proving that the UiO-66-F4 / MIP@Ti3C2T x Molecularly imprinted modified electrodes exhibit good stability.

[0073] 6. Detection and analysis of trifluoroacetic acid in actual water samples

[0074] Tap water and Xiangjiang River water (diluted 1000 times) were selected for testing. The UiO-66-F4 / MIP@Ti3C2T prepared in Example 1 was used for testing. x Molecularly imprinted modified electrodes were used for the quantitative determination and spiked recovery of trifluoroacetic acid in actual water samples (tap water and Xiangjiang River water). The test results are shown in Table 1 below.

[0075] Table 1

[0076]

[0077] As shown in Table 1, the recovery rate of the material in actual water bodies ranged from 96.42% to 108.66%. After repeated tests, the RSD of the test results was below 10%, indicating that the UiO-66-F4 / MIP@Ti3C2T prepared in this invention... x Molecularly imprinted modified electrodes are feasible for detecting trifluoroacetic acid in actual water samples, exhibiting good reproducibility and strong application potential.

[0078] This invention is not limited to the specific embodiments described above. Any modifications made by those skilled in the art based on the above concept without creative effort are within the scope of protection of this invention.

Claims

1. A method for preparing a molecularly imprinted modified electrode for detecting trifluoroacetic acid in water, characterized in that, Includes the following steps: Synthesis of S1 and UiO-66-F4: Tetrafluoroterephthalic acid and zirconium nitrate tetrahydrate were dissolved in a water / glacial acetic acid mixture and refluxed. The reaction product was then treated with anhydrous methanol and anhydrous dichloromethane in sequence and dried under vacuum to obtain UiO-66-F4. S2, Molecularly Imprinted Composite Material UiO-66-F4 / MIP@Ti3C2T x Synthesis: Trifluoroacetic acid and methacrylic acid were dissolved in acetonitrile for pre-assembly; UiO-66-F4 and monolayer Ti3C2T were added to the system. x Azobisisobutyronitrile (AIBN) and ethylene glycol dimethacrylate (EDMA) were polymerized under nitrogen gas. After centrifugation, the mixture was washed with a methanol / glacial acetic acid mixture to remove template molecules, and then dried to obtain the molecularly imprinted composite material UiO-66-F4 / MIP@Ti3C2T. x ; S3, UiO-66-F4 / MIP@Ti3C2T x Preparation of molecularly imprinted modified electrodes: The molecularly imprinted composite material UiO-66-F4 / MIP@Ti3C2T was used. x Dissolved in an ultrapure water / ethanol mixture, ultrasonically mixed, and the mixture was drop-coated onto the electrode surface to obtain UiO-66-F4 / MIP@Ti3C2T x Molecularly imprinted modified electrodes.

2. The method for preparing a molecularly imprinted modified electrode according to claim 1, characterized in that, In step S1, the ratio of tetrafluoroterephthalic acid to zirconium nitrate tetrahydrate is 0.65~0.70g:1.30~1.40g; the reflux reaction temperature is 105~115℃, and the reaction time is 24~25h.

3. The method for preparing a molecularly imprinted modified electrode according to claim 1, characterized in that, In step S1, the anhydrous methanol soaking time is 70-75 hours, and the anhydrous dichloromethane soaking time is 72-75 hours; the vacuum drying temperature is 115-125°C, and the drying time is 24-25 hours.

4. The method for preparing a molecularly imprinted modified electrode according to claim 1, characterized in that, In step S2, the trifluoroacetic acid, methacrylic acid, acetonitrile, UiO-66-F4, and monolayer Ti3C2T are... x The dosage ratio of azobisisobutyronitrile (AIBN) and ethylene glycol dimethacrylate (EDMA) is 1.0~1.1 mmol: 4.0~4.2 mmol: 40~42 mL: 290~310 mg: 290~310 mg: 60~65 mg: 6.0~6.2 mmol.

5. The method for preparing a molecularly imprinted modified electrode according to claim 1, characterized in that, In step S2, the pre-assembly temperature is room temperature and the time is 12-13 hours; the polymerization reaction temperature is 63-67°C and the reaction time is 12-13 hours.

6. The method for preparing a molecularly imprinted modified electrode according to claim 1, characterized in that, In step S3, the volume ratio of water to ethanol in the water / ethanol mixed solvent is 1~3:1, and the ultrasonic mixing time is 2~3h.

7. A molecularly imprinted modified electrode for detecting trifluoroacetic acid in water, characterized in that, It is prepared by the preparation method according to any one of claims 1-6.

8. The application of the molecularly imprinted modified electrode as described in claim 7 in the detection of trifluoroacetic acid in water.

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