Ti3C2Tx-S-PEDOT: PSS / GCE modified electrode and Cd < 2 + >, Pb < 2 + >, Cu < 2 + > and Hg < 2 + > simultaneous detection method thereof

Abstract

The invention discloses a Ti3C2Tx-S-PEDOT: PSS / GCE modified electrode and a method for simultaneously detecting Cd < 2 + >, Pb < 2 + >, Cu < 2 + > and Hg < 2 + > thereof. The material is mainly prepared by compounding Ti3C2Tx-S MXene and PEDOT: PSS and then loading the compounded material on a glassy carbon electrode GCE. The preparation method comprises the following steps: adding Ti3C2Tx-S powder into a mixed solution composed of sodium citrate and F127, stirring, adding PEDOT: PSS for reaction, centrifugally collecting suspended solids, washing with deionized water, freeze-drying to obtain a composite material, preparing a dispersion liquid from the composite material, and dropwise adding the dispersion liquid onto a polished and cleaned glassy carbon electrode GCE for treatment to obtain a modified electrode product. According to the invention, PEDOT: PSS conductive hydrogel is introduced to the surface of Ti3C2Tx-S MXene, so that the problem of poor electrochemical stability of two-dimensional lamellar Ti3C2Tx MXene to Cd < 2 + >, Pb < 2 + >, Cu < 2 + > and Hg < 2 + > can be solved, and meanwhile, the storage stability of the material is improved; the developed novel electrode material improves the sensitivity, anti-interference performance, stability and repeatability of electrochemical rapid detection of Cd < 2 + >, Pb < 2 + >, Cu < 2 + > and Hg < 2 + >.

Description

Technical Field

[0001] This invention relates to a method for the simultaneous detection of multiple metal ions, and in particular to a Ti3C2T method. x -S-PEDOT:PSS / GCE modified electrode and its Cd 2+ Pb 2+ Cu 2+ and Hg 2+ Simultaneous detection method. Background Technology

[0002] Currently, some regions in my country still suffer from heavy metal pollution in food, water sources, and soil. These heavy metal pollutants can directly or indirectly affect agricultural, livestock, and aquatic products, such as rice, milk, and river water, posing serious health risks. Excessive absorption of these heavy metal pollutants can lead to poisoning, impaired development, damage to the immune and reproductive systems, and even cancer. Detection of heavy metal pollution is crucial for risk control, agriculture, and food safety. Electrochemical methods are currently attracting significant attention in the field of heavy metal ion detection due to their high sensitivity, rapid analysis, and ability to simultaneously detect multiple heavy metal ions, making them a popular research area.

[0003] Ti3C2T x -MXene, as a novel electrode material, possesses metal-like conductivity and numerous active sites, enabling electrochemical detection of various heavy metal ions. However, two-dimensional Ti3C2T... x -MXene can stack due to interlayer van der Waals forces and electrostatic interactions, resulting in the loss of a large number of active sites. In addition, the active sites at the material interface can change depending on the water and oxygen conditions of the environment, thereby reducing the electrochemical detection performance of the material.

[0004] PEDOT:PSS hydrogel is a gel material formed from poly[3,4-ethylenedioxythiophene]-polystyrene sulfonate (PEDOT:PSS). PEDOT is a conductive polymer, while PSS is a high-molecular-weight anionic polymer. They form a hydrogel structure through electrostatic interactions, giving it conductivity and solubility. In summary, PEDOT:PSS hydrogel possesses advantages such as conductivity, transparency, flexibility, stretchability, biocompatibility, processability, and environmental friendliness, thus showing broad application prospects in flexible electronics, biomedicine, and energy fields. Summary of the Invention

[0005] To address the problems existing in the background art, the present invention provides a Ti3C2T x -S-PEDOT:PSS / GCE modified electrode and its Cd 2+ Pb2+ Cu 2+ and Hg 2+ Simultaneous detection method, solving the problem of Ti3C2T x MXene sheet materials are easy to stack and store without technical instability issues. This also improves Cd... 2+ Pb 2+ Cu 2+ and Hg 2+ Sensitivity for simultaneous detection.

[0006] The technical solution adopted in this invention is: I. A Ti3C2T x -S-PEDOT:PSS / GCE modified electrode: Mainly composed of Ti3C2T x Ti3C2T was prepared by loading a composite of -S and PEDOT:PSS onto a glassy carbon electrode (GCE). x -S is made from Ti3AlC2 MXene through one-pot etching and in-situ cation-assisted intercalation.

[0007] The Ti3C2T x -S is prepared according to the following method to produce NH4. + Ti3C2T with auxiliary intercalation x That is, Ti3C2T x -S: S1. First, Ti3AlC2 is added to a mixed solution containing LiF, HCl and a certain mass of NH4Cl; S2. Then, stir the reaction magnetically. After the reaction is complete, centrifuge and wash until the pH is reached. S3. Finally, the product is dried in a freeze dryer to obtain the product, which is named Ti3C2T. x -S.

[0008] In S1, the molar ratio of LiF, HCl and NH4Cl in the mixed solution is 1.54:9:0.3, and the molar ratio of Ti3AlC2 and NH4Cl in the mixed solution is 0.06:0.3. In step S2, the reaction is carried out by magnetic stirring at 45 °C for 24 h. After the reaction is completed, the resulting material is repeatedly centrifuged and washed with deionized water until the pH is greater than 6.

[0009] II. A Ti3C2T according to claim 1 x The preparation method of the -S-PEDOT:PSS / GCE modified electrode is as follows: 1) Ti3C2T x-S powder was added to a mixed solution of sodium citrate and F127, and after stirring for a period of time, PEDOT:PSS was added to continue the reaction. Finally, the suspension was collected by centrifugation, washed with deionized water, and freeze-dried to obtain the material, which was named Ti3C2T. x -S-PEDOT:PSS; 2) The glassy carbon electrode was polished on chamois leather with Al2O3 powder of two different particle sizes, 0.3 µm and 0.05 µm, in turn. The glassy carbon electrode was then placed in an ethanol solution for ultrasonic treatment, and then the electrode was cleaned under ultrasonic conditions. Take Ti3C2T x -S-PEDOT:PSS composite material is added to deionized water and ultrasonically dispersed to obtain a uniform dispersion. The dispersion is then dropped onto the central region of the glassy carbon electrode (GCE) to modify the material onto the glassy carbon electrode. Finally, it is dried overnight at room temperature to obtain the modified electrode products corresponding to each raw material.

[0010] In step 1), Ti3C2T x After adding -S to the mixed solution, the reaction proceeds at 25 °C for 8–16 h, forming Ti3C2T. x The mass ratio of -S to sodium citrate and F127 in the mixed solution is 20:(0.375~15):(0.025~0.2) mg, the concentration of sodium citrate in the mixed solution is 0.015~0.6 mg / mL, and the concentration of added F127 is 0.001~0.008 mg / mL.

[0011] In step 1), after adding PEDOT:PSS, the reaction is carried out at 25 °C for 10 h, wherein the concentration of the PEDOT:PSS solution is 0.25~1.5 mg / mL, and the Ti3C2T... x The mass ratio of -S and PEDOT:PSS is 20:(6.25~37.5)mg.

[0012] III. Ti3C2T x The application of -S-PEDOT:PSS / GCE modified electrodes in Cd 2+ Pb 2+ Cu 2+ and Hg 2+ Applications in detection.

[0013] For Cd 2+ Pb 2+ Cu 2+ and Hg 2+ Applications for simultaneous detection.

[0014] IV. A Ti3C2T x-S-PEDOT: PSS / GCE modified electrode Cd 2+ Pb 2+ Cu 2+ and Hg 2+ Simultaneous detection method: using the aforementioned Ti3C2T x A three-electrode detection system was established using a -S-PEDOT:PSS / GCE modified electrode as the working electrode. The test solution was added to the system for electrochemical detection. The electrolyte pH was 3.5–6.5, the pre-deposition potential was -1.4–(-0.9) V, and the pre-enrichment time was 50–250 s. Spiked recovery experiments were conducted to obtain the peak current parameter. A linear standard curve was plotted based on the peak current parameter, and the Cd content was obtained. 2+ Pb 2+ Cu 2+ and Hg 2+ The concentration results.

[0015] Specifically, a standard curve is plotted based on the peak current and the corresponding ion metal concentration, and the target analyte is detected according to the standard curve. (Cd) 2+ Pb 2+ Cu 2+ and Hg 2+ The limits of detection were 0.23 nmol / L, 0.18 nmol / L, 0.26 nmol / L, and 0.28 nmol / L, respectively.

[0016] The method of this invention is to introduce a polymer of PEDOT:PSS conductive hydrogel onto the surface of MXene material, thereby improving Cd 2+ Pb 2+ Cu 2+ and Hg 2+ Sensitivity and stability of electrode materials for simultaneous detection.

[0017] The beneficial effects of this invention are: The modified electrode material and preparation method of the present invention can overcome the limitations of Ti3C2T x The interlayer adsorption of MXene two-dimensional sheets maintains the original active sites between the sheets; it effectively shields against interference from moisture and oxygen, preventing the denaturation of active sites; and it improves Cd. 2+ Pb 2+ Cu 2+ and Hg 2+ The anti-interference, stability, and repeatability of electrochemical detection were improved, achieving the goal of Cd 2+ Pb 2+ Cu 2+ and Hg 2+ The effect of high-sensitivity simultaneous detection. Attached Figure Description

[0018] Figure 1 It is Ti3C2T x -S-PEDOT: The construction process of PSS / GCE sensing electrodes and their application to Cd 2+ Pb 2+ Cu 2+ and Hg 2+ Simultaneous detection principle diagram; Figure 2 Here is a physical structure characterization diagram of the material: (A) Ti3C2T x -S-PEDOT: SEM image of PSS; (B) Ti3C2T x -S-PEDOT:TEM image of PSS; (C)Ti3C2T x -S-PEDOT:FTIR plot of PSS; (D)Ti3AlC2,Ti3C2T x -S、Ti3C2T x -S-PEDOT: PSS XRD pattern; Figure 3 It is Ti3C2T x -S-PEDOT:PSS XPS full spectrum; Figure 4 These are electrochemical performance graphs of the modified electrode: (A) Cyclic voltammetry (CV); (B) Electrochemical impedance spectroscopy (EIS). Figure 5 It is Ti3C2T x -S-PEDOT:PSS material synthesis optimization results: (A) Sodium citrate reaction time; (B) Sodium citrate concentration; (C) F127 concentration; (D) PEDOT:PSS concentration; Figure 6 Here is a comparison chart of parameter optimization in SWASV: (A) pH; (B) deposition potential; (C) enrichment time; Figure 7 Here is a comparison chart of the storage stability of the materials: ①Ti3C2T x -S;②Ti3C2T x -S-1;③Ti3C2T x -S-2;④Ti3C2T x -S-PEDOT:PSS; Figure 8 Here are the results of cyclic voltammetry stability tests on different materials: (A) Ti3C2T x -S / GCE cycle 2000 times; (B)Ti3C2T x -S-1 / GCE cycle 2000 times; (C)Ti3C2T x-S-PEDOT: PSS / GCE loop 2000 times.

[0019] Figure 9 It is Ti3C2T x SWASV response analysis of S-PEDOT:PSS / GCE for the detection of heavy metal ions alone, and their response to (AB)Cd 2+ (CD)Pb 2+ (EF)Cu 2+ and (GH)Hg 2+ Standard curve plot; Figure 10 It is Ti3C2T x -S-PEDOT: PSS / GCE Simultaneous Analysis of Cd 2+ Pb 2+ Cu 2+ and Hg 2+ The SWASV response (A) and its standard curve (B); Figure 11 It is Ti3C2T x Electrochemical stability assessment diagram of -S-PEDOT:PSS / GCE, where (A) is a comparison of the current response values ​​of the target ion after the addition of interfering substances; (B) five newly prepared Ti3C2T x -S-PEDOT: Comparison of PSS / GCE current response values ​​to metal ions; (C) A Ti3C2T x -S-PEDOT: Comparison of current response values ​​measured 10 times using PSS / GCE; Detailed Implementation

[0020] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0021] like Figure 1 As shown, embodiments of the present invention are as follows: 1. Material preparation 1.1) Ti3C2T x -S: S1. First, slowly add 0.5 g of Ti3AlC2 to a mixed solution containing LiF, HCl and a certain mass of NH4Cl. The molar ratio of LiF, HCl and NH4Cl in the mixed solution is 1.54:9:0.3, and the molar ratio of Ti3AlC2 to NH4Cl in the mixed solution is 0.06:0.3. S2. Then, the reaction was carried out by magnetic stirring at 45 °C for 24 h. After the reaction was completed, the obtained material was repeatedly washed by centrifugation with deionized water until the pH was >6. S3. Finally, the product is dried in a freeze dryer to obtain the product, which is named Ti3C2T. x -S.

[0022] 1.2) Ti3C2T x -S-PEDOT:PSS and Ti3C2T x Preparation of -R-PEDOT:PSS: S1. Under 25 ℃ conditions, Ti3C2T x -S powder is added to a mixed solution of sodium citrate and F127 and reacted for a period of time, in which Ti3C2T x The mass ratio of -S to sodium citrate and F127 in the mixed solution is 20:(0.375~15):(0.025~0.2) mg, the concentration of sodium citrate in the mixed solution is 0.015~0.6 mg / mL, the concentration of F127 is 0.001~0.008 mg / mL, and the reaction time of the mixture is 8~16 h; S2, then PEDOT:PSS is added to continue the reaction, in which Ti3C2T x The mass ratio of -S and PEDOT:PSS was 20:(6.25~37.5) mg, the concentration of the PEDOT:PSS solution was 0.25~1.5 mg / mL, and the reaction was carried out at 25 ℃ for 10 h. Finally, the suspension was collected by centrifugation and washed with deionized water. S3. The material was obtained by freeze-drying and named Ti3C2T. x -S-PEDOT:PSS.

[0023] 1.3) Comparative Example Ti3C2T x Preparation of -S-1: 20 mg Ti3C2T x -S powder was added to a 25 mL mixed solution of 0.15 mg / mL sodium citrate and 0.002 mg / mL F127, then stirred at 25 °C for 12 h, washed with deionized water, and freeze-dried to obtain the material, which was named Ti3C2T. x -S-1 (PEDOT:PSS not included).

[0024] 1.4) Comparative Example Ti3C2T x Preparation of -S-2: 20 mg Ti3C2T x -S powder was added to 25 mL of 0.15 mg / mL sodium citrate solution, stirred at 25 °C for 12 h, washed with deionized water, and freeze-dried to obtain the material, which was named Ti3C2T. x -S-2 (without F127 and PEDOT:PSS).

[0025] 1.5) Preparation of modified electrodes Weigh 5 mg of the prepared electrode material into a test tube, add 1 mL of deionized water, and sonicate to obtain a uniform dispersion. Then, take 5 μL of the obtained dispersion and drop it onto a glassy carbon electrode (GCE). Finally, dry it overnight at room temperature to obtain the corresponding modified electrode product.

[0026] 2. Construction of the electrochemical system The example uses a three-electrode system, with a glassy carbon electrode as the working electrode, an Ag / AgCl electrode as the reference electrode, and a platinum sheet electrode as the counter electrode.

[0027] 2.1) Electrochemical performance evaluation of materials: Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used in the presence of [Fe(CN)6]. 3- / 4- The scan was performed in 0.2 mol / L acetate buffer (ABS) at a scan rate of 0.05 V / s.

[0028] 2.2) Feasibility verification and quantitative detection of heavy metal ions: Cd 2+ Pb 2+ Cu 2+ and Hg 2+ Electrochemical measurements were performed using square wave voltammetry (SWASV) in HCl-NH4Cl (10 mL, 0.2 mol / L) buffer solution.

[0029] 3. Physical structure characterization of materials The examples used scanning electron microscopy (SEM) and transmission electron microscopy (TEM) to study Ti3C2T. x The microstructure and internal morphology of -S-PEDOT:PSS were characterized by X-ray diffraction (XRD) analysis of Ti3C2T. x The crystal structure of -S-PEDOT:PSS was investigated using X-ray photoelectron spectroscopy (XPS) to explore Ti3C2T. x The elemental composition of -S-PEDOT:PSS was further verified using Fourier transform infrared spectroscopy (FTIR) to determine Ti3C2T. x -S-PEDOT: The presence of amino groups on the surface of PSS.

[0030] Specifically, the microstructure of the material is analyzed using SEM and TEM, such as... Figure 2 (A) and Figure 2 As shown in (B), the PEDOT:PSS hydrogel-coated material Ti3C2T exhibits [significance / behavior]. x -S morphology, and Ti3C2T x-S exhibits a well-dispersed two-dimensional nanosheet structure. For example... Figure 2 As shown in (D), XRD patterns were analyzed for Ti3AlC2 and Ti3C2T. x -S and Ti3C2T x -S-PEDOT: The crystal phase structure of PSS, Ti3C2T x -S exhibits a low-intensity diffraction peak at 2θ = 9.10° originating from the (002) plane of Ti. The addition of PEDOT:PSS affects the diffraction of Ti3C2T. x The phase structure of -S-PEDOT:PSS is minimally affected. The (002) peak of Ti shifts slightly from 9.10° to 8.87°, indicating that PEDOT:PSS has a small effect on the phase structure of Ti3C2T. x Successful embedding between nanosheets increases the interlayer spacing. For example... Figure 2 As shown in (C), the infrared analysis at 3445 cm⁻¹... -1 The stretching vibrations of OH and NH in water molecules increased with the addition of PEDOT:PSS, reaching 1628 cm⁻¹. -1 The peak at this point is also attributed to strong hydrogen bonds (OH) and absorbed external water or strongly coordinated H₂O, indicating the presence of -OH groups in Ti₃C₂T. x -S and Ti3C2T x -S-PEDOT:PSS composite material, 586 cm -1 The peak value at this point represents Ti-O tensile vibration, ranging from 3000 to 2700 cm⁻¹. -1 This is the CH stretching vibration region (CH stretching vibration on saturated carbon (including CH on aldehyde groups)), 1298 cm⁻¹ -1 (CC) represents PEDOT:PSS. For example... Figure 3 As shown, XPS was used to analyze the Ti3C2T x Further analysis of the elemental composition of -S-PEDOT:PSS clearly reveals Ti3C2T. x -S-PEDOT: Signals for C, N, O, Na, F, and Ti elements in PSS.

[0031] 4. Analysis of the electrochemical performance characterization results of the materials The example uses CV to detect bare GCE and Ti3C2T. x -S / GCE and Ti3C2T x -S-PEDOT:PSS / GCE in [Fe(CN)6] 3- / 4- Electrochemical reactions in solution. For example... Figure 4 As shown in (A), the peak anode current (I) of the bare GCE pa The anode depth is 9 μA. Compared to bare GCE, Ti3C2T... x-S / GCE (I pa =39 μA), Ti3C2T x -S-PEDOT:PSS / GCE (I pa =63μA), the redox current of which was the largest in the CV curve. In the example, EIS was used to detect the interface characteristics of the electrode, such as... Figure 4 As shown in the EIS spectrum of (B), Ti3C2T x -S-PEDOT:PSS / GCE exhibits a smaller R ct The numerical values ​​indicate that the charge transfer resistance is low, which is beneficial for electron transfer between the electrode interfaces, consistent with the CV results. This indicates that the material Ti3C2T x -S-PEDOT:PSS provides a higher electroactive surface area and more electroactive sites to promote ion transfer, thereby accelerating the charge transfer rate throughout the electrochemical process.

[0032] 5. Ti3C2T x -S-PEDOT: PSS Synthesis Method Optimization To obtain the best performance Ti3C2T x -S-PEDOT: PSS material, such as Figure 5 As shown, during the experiment, Ti3C2T was subjected to different treatments. x The reaction time, sodium citrate concentration, F127 concentration, and PEDOT:PSS concentration of sodium citrate were optimized in the -S-PEDOT:PSS etching method.

[0033] 5.1) Reaction time of sodium citrate: 8 h, 12 h, and 16 h; 5.2) Concentrations of sodium citrate: 0.015, 0.045, 0.075, 0.3, 0.45, and 0.6 mg / mL; 5.3) Concentrations of F127: 0.001, 0.004, 0.006, and 0.008 mg / mL; 5.4) PEDOT:PSS concentrations: 0.25, 0.5, 1 and 1.5 mg / mL.

[0034] SWASV was used to study the heavy metal Cd. 2+ Pb 2+ Cu 2+ and Hg 2+ Electrochemical testing was performed to compare performance differences. Results showed that Ti3C2T x The optimal conditions for the -S-PEDOT:PSS etching method are: 0.45 mg / mL sodium citrate, 0.006 mg / mL LF127 and 1 mg / mL LPEDOT:PSS reacted at room temperature for 12 h to achieve the best material properties.

[0035] 6. Ti3C2T x -S-PEDOT:PSS / GCE Electrochemical Detection of Cd 2+ Pb 2+ Cu 2+ and Hg 2+ Optimization of experimental conditions To make the prepared Ti3C2T x -S-PEDOT: PSS / GCE sensing electrode for heavy metal Cd 2+ Pb 2+ Cu 2+ and Hg 2+ It exhibits optimal detection performance; the examples demonstrate optimized experiments under various conditions, including the same concentration of Cd. 2+ Pb 2+ Cu 2+ and Hg 2+ SWASV was detected in HCl-NH4Cl buffer solution: 6.1) Enrichment time: 50, 100, 150, 200, and 250 s, such as Figure 6 As shown in (C); 6.2) Electrodeposition voltages: -1.4, -1.3, -1.2, -1.1, -1.0, and -0.9 V, such as... Figure 6 As shown in (B); 6.3) pH values ​​of HCl-NH4Cl buffer solutions: 3.5, 4, 4.5, 5, and 5.5, as follows: Figure 6 As shown in (A).

[0036] The optimal experimental conditions were obtained as follows: deposition time of 150 s, deposition voltage of -1.2 V, and pH of buffer solution of 5.0.

[0037] 7. Ti3C2T x -S-PEDOT: Storage stability verification of PSS material Ti3C2T x The stability of MXene materials depends on their resistance to aggregation under specific conditions. By detecting whether aggregation occurs, the stability and durability of the material in actual use can be determined. Therefore, this experiment selected ①Ti3C2T to investigate the aggregation time of MXene materials. x -S、②Ti3C2T x -S-1、③Ti3C2T x -S-2 and ④Ti3C2T x The four groups of samples -S-PEDOT:PSS were subjected to long-term stability tests, and photographs were taken and recorded on days 7, 21, and 60 (storage conditions: 4 ℃, sealed).

[0038] The results are as follows Figure 7 As shown, after 60 days, the fourth group of Ti3C2T x -S-PEDOT:PSS maintained good stability, while other groups showed varying degrees of precipitation. These results indicate that PEDOT:PSS can significantly improve the stability of the composite material Ti3C2T. x -S-PEDOT: Stability of PSS.

[0039] 8. Ti3C2T x -S-PEDOT:PSS / GCE Electrochemical Detection of Cd 2+ Pb 2+ Cu 2+ and Hg 2+ Quantitative detection Under optimal test conditions (deposition time: 150 s, deposition voltage: -1.2 V, pH: 5), Ti3C2T was used. x -S-PEDOT:PSS / GCE for the simultaneous and separate detection of Cd in NH4Cl-HCl buffer solution 2+ Pb 2+ Hg 2+ and Cu 2+ Metal ions. Plot the SWASV response curves and corresponding standard curves for electrochemical sensing of different concentrations of metal ions.

[0040] 8.1) Quantitative performance of heavy metal ions alone: ​​Results are as follows Figure 9 As shown, the increase in current value is directly proportional to the increase in metal ion concentration.

[0041] Cd 2+ The linear fitting equation in the concentration range of 1~600 nmol / L is: I Cd 2+ (μA) = 1.06C Cd 2+ +4.21 (R) 2 =0.9957), and the limit of detection (LOD) was 0.53 nmol / L (S / N=3). Pb 2+ The linear fitting equation in the concentration range of 0.5–550 nmol / L is: I Pb 2+ (μA) = 1.69C Pb 2+ +1.29 (R) 2 =0.9958), and the limit of detection (LOD) was 0.26 nmol / L (S / N=3). Cu 2+The linear fitting equation in the concentration range of 0.5–550 nmol / L is: I Cu 2+ (μA) = 3.86C Cu 2+ -2(R) 2 =0.9965), and the limit of detection (LOD) was 0.79 nmol / L (S / N=3). Hg 2+ The linear fitting equation in the concentration range of 0.5–500 nmol / L is: I Hg 2+ (μA) = 6.73C Hg 2+ +1.32 (R) 2 =0.9947), and the limit of detection (LOD) was 0.32 nmol / L (S / N=3).

[0042] Ti3C2T x -S-PEDOT:PSS / GCE for the separate detection of heavy metal Cd 2+ Pb 2+ Cu 2+ and Hg 2+ It has excellent performance in this aspect.

[0043] 8.2) Quantitative performance for simultaneous detection of heavy metal ions: such as... Figure 10 As shown, four well-resolved peaks were observed, and the increase in current value was proportional to the increase in metal ion concentration.

[0044] Cd 2+ The linear fitting equation in the concentration range of 0.5–550 nmol / L is: I Cd 2+ (μA) = 5.79C Cd 2+ +1.911 (R) 2 =0.997), and the limit of detection (LOD) was 0.23 nmol / L (S / N=3). Pb 2+ The linear fitting equation in the concentration range of 0.5–550 nmol / L is: I Pb 2+ (μA) = 1.79C Pb 2+ +2.42 (R) 2 =0.9943), and the limit of detection (LOD) was 0.18 nmol / L (S / N=3). Cu 2+ The linear fitting equation in the concentration range of 0.5–550 nmol / L is: I Cu2+ (μA) = 8.15C Cu 2+ +1.59 (R) 2 =0.9911), and the limit of detection (LOD) was 0.28 nmol / L (S / N=3). Hg 2+ The linear fitting equation in the concentration range of 0.5–550 nmol / L is: I Hg 2+ (μA) = 8.78C Hg 2+ +5.82 (R) 2 =0.9956), and the limit of detection (LOD) was 0.26 nmol / L (S / N=3).

[0045] Ti3C2T x -S-PEDOT: PSS / GCE for simultaneous detection of heavy metal Cd 2+ Pb 2+ Cu 2+ and Hg 2+ It also exhibits excellent performance in this aspect. The electrochemical sensor of this invention has a lower detection limit, a simple and mild preparation method, and can bind to heavy metal ions through direct complexation. In addition, the modified electrode surface is easy to clean.

[0046] 9. Ti3C2T x Electrochemical immunity, stability and reproducibility testing of -S-PEDOT:PSS / GCE 9.1) Anti-interference performance: To verify the constructed Ti3C2T x -S-PEDOT:PSS / GCE sensing electrode in electrochemical detection of Cd 2+ Pb 2+ Cu 2+ and Hg 2+ To assess the anti-interference performance, common interfering ions (Ca) were selected. 2+ K + Mg 2+ Na + Zn 2+ Mn 2+ SO4 2- And Al 3+ Anti-interference studies were conducted on [various substances]. The target ion (Cd) was simultaneously added to the HCl-NH4Cl buffer solution. 2+ Pb 2+ Cu 2+ and Hg 2+The target ion concentration was 100 times that of the interfering ion concentration. SWASV tests were performed on both ions, and the current values ​​before and after the addition of interfering ions were compared to investigate the effects of adding interfering ions on Ti3C2T. x -S-PEDOT: PSS's anti-interference performance. Results are as follows... Figure 11 As shown in (A), when interfering ions coexist, the current response does not change significantly, and the relative standard deviation (RSD) is controlled between 1.01 and 4.95%.

[0047] 9.2) Stability: First, in a solution containing the same concentration of Cd 2+ Pb 2+ Cu 2+ and Hg 2+ In HCl-NH4Cl buffer, a Ti3C2T sample was prepared. x -S-PEDOT: PSS / GCE continuously test SWASV 10 times, the results are as follows Figure 11 As shown in (C), the RSD of the results of 10 repeated experiments with one electrode is <5%.

[0048] In addition, Ti3C2T x -S / GCE, Ti3C2T x -S-1 / GCE and Ti3C2T x -S-PEDOT: The PSS / GCE sensing electrodes are respectively located in the [Fe(CN)6] group. 3- / 4- CV scans were performed once, 1000 times, and 2000 times in 0.2 mol / L phosphate-buffered saline (PBS) to investigate the effect of the conductive hydrogel PEDOT:PSS on the composite material Ti3C2T. x -S improves stability. The results are as follows: Figure 8 As shown. Ti3C2T x -S-PEDOT:PSS / GCE maintained a high response rate even after 2000 scans, mainly due to the stabilizing effect of the conductive hydrogel PEDOT:PSS, while Ti3C2T x -S / GCE's response rate is much lower than that of Ti3C2T. x The main reason for -S-PEDOT:PSS / GCE is the lack of sodium citrate, F127, and PEDOT:PSS, which greatly reduces its signal.

[0049] 9.3) Repeatability: Ten different batches of Ti3C2T were selected. x -S-PEDOT: Reproducibility was evaluated using the current response obtained from PSS / GCE, with each electrode subjected to the same concentration of Cd. 2+ Pb 2+ Cu 2+ and Hg2+ SWASV was tested in HCl-NH4Cl buffer. Figure 11 As shown in (B), the RSD remains between 0.99 and 4.66%.

[0050] Therefore, this invention realizes a method for enhancing the composite material Ti3C2T using PEDOT:PSS hydrogel. x The stability and electrochemical performance of -S were studied, and a novel chemical sensor was developed to simultaneously determine multiple heavy metal ions.

[0051] The above specific embodiments are used to explain and illustrate the present invention, but not to limit the present invention. Any modifications and changes made to the present invention within the spirit and scope of the claims shall fall within the protection scope of the present invention.

[0052] The above description is only a preferred embodiment of the present invention. Therefore, all equivalent changes or modifications made to the structure, features and principles described in the claims of this patent application are included in the scope of this patent application.

Claims

1. A Ti3C2T x -S-PEDOT:PSS / GCE modified electrode, characterized in that: Mainly composed of Ti3C2T x Ti3C2T was prepared by loading a glassy carbon electrode (GCE) with composites of -S and PEDOT:PSS. x -S is made from Ti3AlC2 MXene through one-pot etching and in-situ cation-assisted intercalation.

2. A Ti3C2T according to claim 1 x -S-PEDOT:PSS / GCE modified electrode, characterized in that: The Ti3C2T x -S is prepared according to the following method: S1. First, add Ti3AlC2 to a mixed solution containing LiF, HCl and NH4Cl; S2. Then, stir the reaction magnetically. After the reaction is complete, centrifuge and wash until the pH is reached. S3. Finally, the product is dried in a freeze dryer to obtain the final product.

3. A Ti3C2T according to claim 2 x -S-PEDOT:PSS / GCE modified electrode, characterized in that: In S1, the molar ratio of LiF, HCl and NH4Cl in the mixed solution is 1.54:9:0.3, and the molar ratio of Ti3AlC2 and NH4Cl in the mixed solution is 0.06:0.

3. In step S2, the reaction is carried out by magnetic stirring at 45 °C for 24 h. After the reaction is completed, the resulting material is repeatedly centrifuged and washed with deionized water until the pH is greater than 6.

4. A Ti3C2T according to claim 1 x The method for preparing -S-PEDOT:PSS / GCE modified electrodes is characterized by: The preparation process is as follows: 1) Ti3C2T x -S powder was added to a mixed solution of sodium citrate and F127, stirred, and then PEDOT:PSS was added to continue the reaction. Finally, the suspension was collected by centrifugation, washed with deionized water, and freeze-dried to obtain the material. 2) The glassy carbon electrode was polished on chamois leather with two different Al2O3 powders of different particle sizes in turn, and then the glassy carbon electrode was ultrasonically treated in ethanol solution, and then the electrode was cleaned under ultrasonic conditions. Take Ti3C2T x -S-PEDOT:PSS composite material was added to deionized water and then sonicated to obtain a uniform dispersion. The dispersion was then dropped onto the central region of the glassy carbon electrode GCE and finally dried overnight at room temperature to obtain the modified electrode product.

5. The Ti3C2T according to claim 4 x The method for preparing -S-PEDOT:PSS / GCE modified electrodes is characterized by: In step 1), Ti3C2T x After adding -S to the mixed solution, the reaction proceeds at 25 °C for 8–16 h, forming Ti3C2T. x The mass ratio of -S to sodium citrate and F127 in the mixed solution is 20:(0.375~15):(0.025~0.2), the concentration of sodium citrate in the mixed solution is 0.015~0.6 mg / mL, and the concentration of added F127 is 0.001~0.008 mg / mL.

6. The Ti3C2T according to claim 4 x The method for preparing -S-PEDOT:PSS / GCE modified electrodes is characterized by: In step 1), after adding PEDOT:PSS, the reaction is carried out at 25 °C for 10 h, wherein the concentration of the PEDOT:PSS solution is 0.25~1.5 mg / mL, and the Ti3C2T... x The mass ratio of -S and PEDOT:PSS is 20:(6.25~37.5)mg.

7. The Ti3C2T according to any one of claims 1-3 x -S-PEDOT: PSS / GCE modified electrode or Ti3C2T prepared by any of the methods described in claims 4-6 x The application of -S-PEDOT:PSS / GCE modified electrodes is characterized by: In Cd 2+ Pb 2+ Cu 2+ and Hg 2+ Applications in detection.

8. The application according to claim 7, characterized in that: For Cd 2+ Pb 2+ Cu 2+ and Hg 2+ Applications for simultaneous detection.

9. A Ti3C2T based on any one of claims 1-3 x -S-PEDOT: PSS / GCE modified electrode or Ti3C2T prepared by any of the methods described in claims 4-6 x -S-PEDOT: PSS / GCE modified electrode Cd 2+ Pb 2+ Cu 2+ and Hg 2+ Simultaneous detection method, characterized in that: With the aforementioned Ti3C2T x A three-electrode detection system was established using a -S-PEDOT:PSS / GCE modified electrode as the working electrode. The test solution was added to the three-electrode detection system for electrochemical detection, and the peak current parameter was obtained. A linear standard curve was plotted based on the peak current parameter to obtain Cd. 2+ Pb 2+ Cu 2+ and Hg 2+ The concentration results.

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