An electrochemical sensor for detecting mercury ions, preparation method and application thereof

Abstract

The present invention provides an electrochemical sensor, preparation method and application for detecting mercury ions, belonging to the field of electrochemical analysis. In the present invention, accordion-shaped titanium carbide is obtained by etching aluminum carbide, and then a nickel metal organic framework is generated in situ on the surface of titanium carbide, and finally titanium dioxide / nickel-nitrogen doped carbon material is obtained by calcining in nitrogen, and the composite material is dispersed in water, and the prepared dispersed droplets are applied to the electrode surface as an electrode material for the detection of mercury ions. The present invention adopts a three-electrode system, silver / silver chloride as a reference electrode, a platinum wire electrode as a counter electrode, and titanium dioxide / nickel-nitrogen doped carbon material is modified on the electrode surface as a working electrode, and mercury ions are detected by differential pulse anodic stripping voltammetry. The electrochemical sensor constructed in the present invention has the advantages of low detection limit, high sensitivity, good selectivity, simple preparation method, etc., and has good application prospects in the fields of environmental monitoring, food safety detection, etc.

Description

Technical Field

[0001] The invention belongs to the field of electrochemical analysis and relates to an electrochemical sensor for detecting mercury ions, a preparation method and application thereof. Background Art

[0002] Mercury is listed as one of the top ten chemicals of public health concern by the World Health Organization. Its presence in environmental media can cause serious heavy metal pollution. Mercury exists in three forms in environmental media: elemental mercury, inorganic mercury and organic mercury. Mercury can be transformed through physical, chemical and biological processes. 2+ ) is a highly toxic pollutant with acute toxicity that can cause serious damage to multiple physiological systems of the human body. Therefore, it is necessary to develop a fast, sensitive, and low-cost Hg 2+ Detection technology is crucial.

[0003] Common mercury detection techniques include cold atomic fluorescence, inductively coupled plasma mass spectrometry, cold atomic absorption spectroscopy and other methods. These detection methods usually require large instruments and equipment, complex pre-treatment processes and complex operations. In contrast, electrochemical sensors have the advantages of simple operation, rapid detection, high sensitivity, good selectivity and good stability. At present, a variety of materials such as carbon nanomaterials and metal nanomaterials are used as electrode materials to improve the performance of electrochemical sensors. Among them, the high conductivity of two-dimensional transition metal carbon / nitride (MXene) and the large surface area of ​​metal organic framework (MOF) make it play an important role in the development of electrochemical sensors. In recent years, MXene / MOF composites and their derivatives have also received widespread attention in electrochemical sensing. Summary of the invention

[0004] The purpose of the present invention is to provide an electrochemical sensor for sensitively detecting mercury ions, which has the advantages of high sensitivity, low detection limit, good selectivity, simple operation, etc.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows:

[0006] A method for preparing an electrochemical sensor for detecting mercury ions comprises the following steps:

[0007] (1) Preparation of titanium carbide:

[0008] Slowly adding aluminum carbide to a hydrogen fluoride solution, wherein 0.5-1.5 g of aluminum carbide is added to every 20 mL of hydrogen fluoride solution, etching at room temperature for 12-36 hours to remove aluminum in the aluminum carbide, then centrifuging and washing the product until the pH of the supernatant is 5-7, filtering and collecting the solid, and vacuum drying to obtain a titanium carbide product;

[0009] (2) Preparation of titanium carbide / nickel metal organic framework composite materials:

[0010] First, the titanium carbide obtained in step (1) is dispersed in water to obtain a dispersion A, wherein 0.3-0.6 g of titanium carbide is dispersed in every 10 mL of water; then 2-methylimidazole is dispersed in the dispersion A to obtain a dispersion B, wherein 1 g of 2-methylimidazole is added to every 10 mL of the dispersion A;

[0011] Secondly, nickel acetate tetrahydrate was dispersed in water to prepare dispersion C, wherein 0.505 g of nickel acetate tetrahydrate was dispersed in every 10 mL of water;

[0012] Finally, the dispersion B and the dispersion C are preheated to 85-95° C. respectively, and then the dispersion C is slowly poured into the dispersion B. Under an argon atmosphere, the obtained mixed solution is reacted at 85-95° C. for 30-90 minutes (stirred during the reaction) to allow the nickel ions and the 2-methylimidazole ligand to combine, and then cooled in an ice bath, washed by centrifugation with deionized water, and the solid is collected by filtration, and dried in a vacuum drying oven to obtain a titanium carbide / nickel metal organic framework composite material;

[0013] (3) Preparing titanium dioxide / nickel-nitrogen doped carbon material: calcining the titanium carbide / nickel metal organic framework composite material obtained in step (2) at 400-600° C. for 0.5-1.5 h in a nitrogen atmosphere, and cooling naturally to obtain a titanium dioxide / nickel-nitrogen doped carbon material;

[0014] (4) dispersing the titanium dioxide / nickel-nitrogen doped carbon material obtained in step (3) in deionized water at room temperature to obtain a composite material dispersion, wherein the concentration of the titanium dioxide / nickel-nitrogen doped carbon material is 2-6 mg / mL;

[0015] (5) Polishing the glassy carbon electrode;

[0016] (6) uniformly dripping the composite material dispersion obtained in step (4) onto the surface of the glassy carbon electrode and drying it at room temperature to obtain a composite electrode modified with titanium dioxide / nickel-nitrogen-doped carbon material; wherein each 0.071 cm 2 2-8 μL of the composite material dispersion is added dropwise to the surface of the glassy carbon electrode.

[0017] (7) Using a three-electrode system, the composite electrode obtained in step (6) is used as a working electrode, silver / silver chloride is used as a reference electrode, and a platinum wire electrode is used as a counter electrode to obtain an electrochemical sensor.

[0018] An electrochemical sensor for detecting mercury ions is prepared by the method.

[0019] An application of an electrochemical sensor for detecting mercury ions, which is applied to detect mercury ions in a sample, specifically comprising the following steps:

[0020] (1) Draw a standard curve for mercury ions

[0021] First, the mercury ion solution was diluted with acetic acid-sodium acetate buffer as the electrolyte; then, differential pulse anodic stripping voltammetry was used for detection, and the detection range of mercury ion concentration was 1×10 -9 -1×10 -5 molL -1 , draw a standard curve based on the linear relationship between the current peak value of the voltammetric curve and the mercury ion concentration;

[0022] (2) Actual sample testing

[0023] The prepared electrochemical sensor is used to detect mercury ions in the actual sample by differential pulse anodic stripping voltammetry. The obtained current peak is substituted into the standard curve obtained in step (1) to calculate the concentration of mercury ions in the actual sample.

[0024] The beneficial effects of the present invention are:

[0025] The present invention uses titanium dioxide / nickel-nitrogen doped carbon material for the detection of mercury ions to construct an electrochemical sensor for detecting mercury ions. The electrochemical sensor does not require complicated pre-treatment work and has the advantages of simple operation, high sensitivity, good selectivity, strong stability, etc., and can achieve efficient and rapid detection of mercury ions. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 Scanning electron microscopy (SEM) images of (A) aluminum carbide, (B) titanium carbide, (C) titanium carbide / nickel metal organic framework composites, and (D) titanium dioxide / nickel-nitrogen doped carbon materials.

[0027] Figure 2 Differential pulse anodic stripping voltammetry curves of mercury ions at different concentrations (A) 1×10 -6 -1×10 - 5 molL -1 (B) 0-1×10 -6 molL -1 、(C)0-1×10 -7 molL -1 (Partial enlarged view of B).

[0028] Figure 3 This is a linear relationship diagram between different concentrations of mercury ions and their current peak values. DETAILED DESCRIPTION

[0029] In order to make the purpose, technical method and advantages of the present invention more clear, the present invention is further described in detail in combination with embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the scope of the present invention.

[0030] Example 1

[0031] A method for preparing a sensor for mercury ion detection:

[0032] (1) Preparation of titanium carbide: Aluminum carbide is slowly added to a hydrogen fluoride solution, wherein 1 g of aluminum carbide is added to every 20 mL of hydrogen fluoride solution, and the solution is etched at room temperature for 24 h to remove the aluminum in the aluminum carbide. The product is then centrifuged and washed until the pH of the supernatant is 7, and the solid is collected by filtration, and then vacuum dried to obtain a titanium carbide product;

[0033] (2) Preparing a titanium carbide / nickel metal organic framework composite material: dispersing the titanium carbide obtained in step (1) in water to obtain a dispersion A, wherein 0.4 g of titanium carbide is dispersed in every 10 mL of water;

[0034] Then, 2-methylimidazole was dispersed in dispersion A to obtain dispersion B, wherein 1 g of 2-methylimidazole was added to every 10 mL of dispersion A;

[0035] Dispersing nickel acetate tetrahydrate in water to prepare dispersion C, wherein 0.505 g of nickel acetate tetrahydrate is dispersed per 10 mL of water;

[0036] Preheating dispersions B and C to 95° C., then slowly pouring dispersion C into dispersion B, reacting the mixture at 95° C. for 30 minutes (stirring during the reaction) under an argon atmosphere to allow nickel ions to bind to 2-methylimidazole ligands, then cooling in an ice bath, washing with deionized water by centrifugation, collecting solids by filtration, and drying in a vacuum drying oven to obtain a titanium carbide / nickel metal organic framework composite material;

[0037] (3) Preparing titanium dioxide / nickel-nitrogen doped carbon material: calcining the titanium carbide / nickel metal organic framework composite material obtained in step (2) at 600° C. for 0.5 h in a nitrogen atmosphere, and cooling naturally to obtain a titanium dioxide / nickel-nitrogen doped carbon material;

[0038] (4) at room temperature, dispersing the titanium dioxide / nickel-nitrogen doped carbon material obtained in step (3) in deionized water to obtain a composite material dispersion, wherein the concentration of the titanium dioxide / nickel-nitrogen doped carbon material is 4 mg / mL;

[0039] (5) Polishing the glassy carbon electrode;

[0040] (6) The composite material dispersion obtained in step (4) is evenly added dropwise to the surface of the glassy carbon electrode and dried at room temperature to obtain a composite electrode modified with titanium dioxide / nickel-nitrogen doped carbon material, wherein each 0.071 cm 2 5 μL of the composite material dispersion was added dropwise to the surface of the glassy carbon electrode.

[0041] (7) Using a three-electrode system, the composite electrode obtained in step (6) is used as a working electrode, silver / silver chloride is used as a reference electrode, and a platinum wire electrode is used as a counter electrode to obtain an electrochemical sensor.

[0042] The scanning electron microscope images (SEM) of the aluminum carbide (A), titanium carbide (B), titanium carbide / nickel metal organic framework composite material (C) and titanium dioxide / nickel-nitrogen doped carbon material (D) involved in this embodiment are shown in the attached figure. Figure 1 As shown. Figure 1 It can be seen that the titanium carbide formed by etching of aluminum carbide has a smooth surface and an accordion-shaped structure; the titanium carbide / nickel metal organic framework composite material presents a rough, wrinkled multilayer structure; a large amount of particles are generated on the surface of the titanium dioxide / nickel-nitrogen doped carbon material derived from the titanium carbide / nickel metal organic framework composite material, indicating the successful preparation of the titanium dioxide / nickel-nitrogen doped carbon material.

[0043] Example 2

[0044] A method for preparing a sensor for mercury ion detection:

[0045] (1) Preparation of titanium carbide: Aluminum carbide is slowly added to a hydrogen fluoride solution, wherein 0.5 g of aluminum carbide is added to every 20 mL of hydrogen fluoride solution, and the solution is etched at room temperature for 12 h to remove the aluminum in the aluminum carbide. The product is then centrifuged and washed until the pH of the supernatant is 5, and then filtered and vacuum dried to obtain a titanium carbide product.

[0046] (2) Preparing a titanium carbide / nickel metal organic framework composite material: dispersing the titanium carbide obtained in step (1) in water to obtain a dispersion A, wherein 0.3 g of titanium carbide is dispersed in every 10 mL of water;

[0047] Then, 2-methylimidazole was dispersed in dispersion A to obtain dispersion B, wherein 1 g of 2-methylimidazole was added to every 10 mL of dispersion A;

[0048] Dispersing nickel acetate tetrahydrate in water to prepare dispersion C, wherein 0.505 g of nickel acetate tetrahydrate is dispersed per 10 mL of water;

[0049] Preheating dispersions B and C to 85° C., then slowly pouring dispersion C into dispersion B, reacting the mixture at 85° C. for 90 minutes (stirring during the reaction) under an argon atmosphere to allow nickel ions to bind to 2-methylimidazole ligands, then cooling in an ice bath, washing with deionized water by centrifugation, collecting solids by filtration, and drying in a vacuum drying oven to obtain a titanium carbide / nickel metal organic framework composite material;

[0050] (3) Preparing titanium dioxide / nickel-nitrogen doped carbon material: calcining the titanium carbide / nickel metal organic framework composite material obtained in step (2) at 400° C. for 1.5 h under a nitrogen atmosphere, and cooling naturally to obtain a titanium dioxide / nickel-nitrogen doped carbon material;

[0051] (4) at room temperature, dispersing the titanium dioxide / nickel-nitrogen doped carbon material obtained in step (3) in deionized water to obtain a composite material dispersion, wherein the concentration of the titanium dioxide / nickel-nitrogen doped carbon material is 2 mg / mL;

[0052] (5) Polishing the glassy carbon electrode;

[0053] (6) The composite material dispersion obtained in step (4) is evenly added dropwise to the surface of the glassy carbon electrode and dried at room temperature to obtain a composite electrode modified with titanium dioxide / nickel-nitrogen doped carbon material, wherein each 0.071 cm 2 8 μL of the composite material dispersion was added dropwise to the surface of the glassy carbon electrode.

[0054] (7) Using a three-electrode system, the composite electrode obtained in step (6) is used as a working electrode, silver / silver chloride is used as a reference electrode, and a platinum wire electrode is used as a counter electrode to obtain an electrochemical sensor.

[0055] Example 3

[0056] A method for preparing a sensor for mercury ion detection:

[0057] (1) Preparation of titanium carbide: Aluminum carbide is slowly added to a hydrogen fluoride solution, wherein 1.5 g of aluminum carbide is added to every 20 mL of hydrogen fluoride solution, and the solution is etched at room temperature for 36 hours to remove the aluminum in the aluminum carbide. The product is then centrifuged and washed until the pH of the supernatant is 6, and then filtered and vacuum dried to obtain a titanium carbide product.

[0058] (2) Preparing a titanium carbide / nickel metal organic framework composite material: dispersing the titanium carbide obtained in step (1) in water to obtain a dispersion A, wherein 0.6 g of titanium carbide is dispersed in every 10 mL of water;

[0059] Then, 2-methylimidazole was dispersed in dispersion A to obtain dispersion B, wherein 1 g of 2-methylimidazole was added to every 10 mL of dispersion A;

[0060] Dispersing nickel acetate tetrahydrate in water to prepare dispersion C, wherein 0.505 g of nickel acetate tetrahydrate is dispersed per 10 mL of water;

[0061] Preheating dispersions B and C to 90° C., then slowly pouring dispersion C into dispersion B, reacting the mixture at 90° C. for 60 minutes (stirring during the reaction) under an argon atmosphere to allow nickel ions to bind to 2-methylimidazole ligands, then cooling in an ice bath, washing with deionized water by centrifugation, collecting solids by filtration, and drying in a vacuum drying oven to obtain a titanium carbide / nickel metal organic framework composite material;

[0062] (3) Preparing titanium dioxide / nickel-nitrogen doped carbon material: calcining the titanium carbide / nickel metal organic framework composite material obtained in step (2) at 500° C. for 1 h in a nitrogen atmosphere, and cooling naturally to obtain a titanium dioxide / nickel-nitrogen doped carbon material;

[0063] (4) at room temperature, dispersing the titanium dioxide / nickel-nitrogen doped carbon material obtained in step (3) in deionized water to obtain a composite material dispersion, wherein the concentration of the titanium dioxide / nickel-nitrogen doped carbon material is 6 mg / mL;

[0064] (5) Polishing the glassy carbon electrode;

[0065] (6) The composite material dispersion obtained in step (4) is evenly added dropwise to the surface of the glassy carbon electrode and dried at room temperature to obtain a composite electrode modified with titanium dioxide / nickel-nitrogen doped carbon material, wherein each 0.071 cm 2 2 μL of the composite material dispersion was added dropwise to the surface of the glassy carbon electrode.

[0066] (7) Using a three-electrode system, the composite electrode obtained in step (6) is used as a working electrode, silver / silver chloride is used as a reference electrode, and a platinum wire electrode is used as a counter electrode to obtain an electrochemical sensor.

[0067] Example 4

[0068] Application of an electrochemical sensor for detecting mercury ions:

[0069] The electrochemical sensor obtained in Example 1 is used for the detection of mercury ions, and the steps are as follows:

[0070] (1) Determine the optimal pH of acetic acid-sodium acetate buffer

[0071] In an acetic acid-sodium acetate buffer solution containing 1 μmol / L mercuric ions, a titanium dioxide / nickel-nitrogen doped carbon composite electrode was used as the working electrode, and differential pulse anodic stripping voltammetry was used for detection, wherein the pH values ​​of the acetic acid-sodium acetate buffer solution were 3.5, 4.0, 4.5, 5.0, and 5.5, respectively. The parameters were set as follows: enrichment potential was -1.4V; enrichment time was 300s; scanning potential range was 0-0.5V; potential increment was 0.004V; pulse amplitude was 0.05V; and pulse period was 0.1s. By comparing the peak currents in the voltammograms obtained at different pH values, the pH value corresponding to the maximum peak current was taken as the optimal pH value. The optimal pH of the buffer solution in this embodiment was 4.5.

[0072] (2) Determine the optimal enrichment potential of mercury ions

[0073] In an acetic acid-sodium acetate buffer containing 1 μmol / L mercuric ions, differential pulse anodic stripping voltammetry was used for detection. The acetic acid-sodium acetate buffer was the acetic acid-sodium acetate buffer with a pH value of 4.5 determined in step (1), and the enrichment potentials were -1.2V, -1.3V, -1.4V, -1.5V, and -1.6V, respectively, and the parameters were set as follows: enrichment time was 300s; scanning potential range was 0-0.5V; potential increment was 0.004V; pulse amplitude was 0.05V; and pulse period was 0.1s. By comparing the current peaks under different enrichment potentials, it was determined that the optimal enrichment potential in this embodiment was -1.4V.

[0074] (3) Determine the optimal enrichment time of mercury ions

[0075] In an acetic acid-sodium acetate buffer containing 1 μmol / L mercuric ions, differential pulse anodic stripping voltammetry was used for detection, wherein the acetic acid-sodium acetate buffer was an acetic acid-sodium acetate buffer with a pH value of 4.5 determined in step (1), the enrichment potential was the optimal enrichment potential of -1.4V determined in step (2), and the enrichment times were 100s, 200s, 300s, 400s, and 500s, respectively. The parameters were set as follows: scanning potential range of 0-0.5V; potential increment of 0.004V; pulse amplitude of 0.05V; pulse period of 0.1s. By comparing the current peak values ​​at different enrichment times, it was determined that the optimal enrichment time for mercuric ions in this embodiment was 300s.

[0076] (4) Draw the standard curve of mercury ion

[0077] The electrochemical sensor prepared in Example 1 was used to detect mercury ions at concentrations of 1×10 -9 mol L -1 , 1×10 -8 mol L -1 , 1×10-7 mol L -1 , 5×10 -7 mol L -1 , 1×10 -6 mol L -1 , 2.5×10 -6 mol L -1 , 5×10 -6 mol L -1 , 7.5×10 -6 mol L -1 , 1×10 -5 mol L -1 The differential pulse anodic stripping voltammetry method was used for determination, and a standard curve was drawn. The differential pulse anodic stripping voltammetry curves of mercury ions at different concentrations are shown in the attached figure. Figure 2 The standard curve is shown in the attached Figure 3 The sensor can detect mercury ions in a concentration range of 1×10 -9 -1×10 -5 mol L -1 , the concentration range is 1×10 -6 -1×10 -5 mol L -1 The corresponding linear regression equation is I p (μA)=5.47944[C](μM)+11.08334(R 2 =0.99768); concentration range is 1×10 -9 -1×10 -6 mol L -1 The corresponding linear regression equation is I p (μA)=16.43302[C](μM)+0.02261(R 2 =0.99767), where I p represents the peak current when detecting mercury ions, in μA, C represents the concentration of mercury ions, in μM, and the detection limit is 7.9×10 -10 mol L -1 .

[0078] (5) Actual sample testing

[0079] The present invention uses tap water and seawater as actual samples, and filters them with a 0.22 μm filter membrane for subsequent determination. The actual sample after filtration is diluted with an acetic acid-sodium acetate buffer solution with a pH of 4.5, and detected by differential pulse anodic stripping voltammetry, and the parameters are set as follows: enrichment potential is -1.4V; enrichment time is 300s; potential range is 0-0.5V; potential increment is 0.004V; pulse amplitude is 0.05V; pulse period is 0.1s. The current peak value shown in the voltammogram is brought into the linear regression equation obtained in step (4) to calculate the content of mercury ions in the actual sample. The recovery rate of the actual sample is measured by the standard addition method, and the RSD is less than 5.5%, indicating that the electrochemical sensor can be used for the detection of mercury ions in actual samples.

[0080] The above-described embodiments are merely implementation methods of the present invention, but they cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that for those skilled in the art, several modifications and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention.

Claims

1. A method for preparing an electrochemical sensor for detecting mercury ions, characterized in that: The steps include: (1) Preparation of titanium carbide: Slowly adding aluminum carbide to a hydrogen fluoride solution, etching at room temperature for 12-36 hours to remove aluminum in the aluminum carbide, then centrifuging and washing the product until the pH of the supernatant is 5-7, filtering and collecting the solid, and vacuum drying to obtain a titanium carbide product; (2) Preparation of titanium carbide / nickel metal organic framework composite materials: 2.1) dispersing the titanium carbide obtained in step (1) in water to obtain dispersion A, and then dispersing 2-methylimidazole in dispersion A to obtain dispersion B; 2.2) dispersing nickel acetate tetrahydrate in water to prepare dispersion C; 2.3) Preheating dispersion B and dispersion C to 85-95° C. respectively, then slowly pouring dispersion C into dispersion B, reacting the obtained mixed solution at 85-95° C. for 30-90 minutes under an argon atmosphere to allow nickel ions to bind to 2-methylimidazole ligands, then cooling in an ice bath, washing by centrifugation with deionized water, collecting the solid by filtration, and drying in a vacuum drying oven to obtain a titanium carbide / nickel metal organic framework composite material; (3) Preparing titanium dioxide / nickel-nitrogen doped carbon material: calcining the titanium carbide / nickel metal organic framework composite material obtained in step (2) at 400-600° C. for 0.5-1.5 h in a nitrogen atmosphere, and cooling naturally to obtain a titanium dioxide / nickel-nitrogen doped carbon material; (4) dispersing the titanium dioxide / nickel-nitrogen doped carbon material obtained in step (3) in deionized water at room temperature to obtain a composite material dispersion, wherein the concentration of the titanium dioxide / nickel-nitrogen doped carbon material is 2-6 mg / mL; (5) Polishing the glassy carbon electrode; (6) uniformly dropping the composite material dispersion obtained in step (4) onto the surface of the glassy carbon electrode and drying it at room temperature to obtain a composite electrode modified with titanium dioxide / nickel-nitrogen-doped carbon material; (7) Using a three-electrode system, the composite electrode obtained in step (6) is used as a working electrode, silver / silver chloride is used as a reference electrode, and a platinum wire electrode is used as a counter electrode to obtain an electrochemical sensor.

2. The method for preparing an electrochemical sensor for detecting mercury ions according to claim 1, characterized in that: In the step (1), 0.5-1.5 g of aluminum carbide is added to every 20 mL of hydrogen fluoride solution.

3. The method for preparing an electrochemical sensor for detecting mercury ions according to claim 1, characterized in that: In the step 2.1), 0.3-0.6 g of titanium carbide is dispersed in every 10 mL of water, and 1 g of 2-methylimidazole is added to every 10 mL of dispersion A.

4. The method for preparing an electrochemical sensor for detecting mercury ions according to claim 1, characterized in that: In the step 2.2), 0.505 g of nickel acetate tetrahydrate is dispersed in every 10 mL of water.

5. The method for preparing an electrochemical sensor for detecting mercury ions according to claim 1, characterized in that: In the step (6), every 0.071 cm 2 2-8 μL of the composite material dispersion is added dropwise to the surface of the glassy carbon electrode.

6. An electrochemical sensor for detecting mercury ions, characterized in that: The invention is prepared by the preparation method described in any one of claims 1 to 5.

7. An application of an electrochemical sensor for detecting mercury ions according to claim 6, characterized in that: The electrochemical sensor is used to detect mercury ions in a sample.

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