Construction method and application of electrochemical sensor based on nitrogen-doped carbon-cobalt-nickel diatomic catalyst

Abstract

The invention relates to a construction method and application of an electrochemical sensor based on a nitrogen-doped carbon-cobalt-nickel diatomic catalyst. The electrochemical sensor is prepared by modifying the surface of a glassy carbon electrode with a composite material formed by mixing the nitrogen-doped carbon-cobalt-nickel diatomic catalyst and a film-forming material. The electrochemical sensor provided by the invention has high stability and selectivity, has a bimetallic center synergistic effect, shows excellent catalytic performance, remarkably improves the electrochemical reaction activity, and improves the sensitivity of the sensor. The electrochemical sensor has high detection sensitivity and response speed when being used for detecting carbadox, and especially has advantages in trace detection and complex sample interference resistance. The method can be applied to food safety monitoring, such as rapid detection of carbadox residues in animal feed or meat, can also be used for trace detection of nitrofuran drugs in water or soil, and has a wide application prospect.

Description

Technical Field

[0001] The present invention relates to a construction method of an electrochemical sensor based on a nitrogen-doped carbon cobalt nickel diatomic catalyst (CoNi / NC DAC) and an application thereof, belonging to the technical field of material improvement and application thereof. Background Art

[0002] Carbadox is a drug commonly used in food-producing animals, but its use has been banned or restricted in many countries and regions due to its potential harmful effects. Currently, methods for detecting carbadox include liquid chromatography-mass spectrometry (LC-MS / MS) and enzyme-linked immunosorbent assay (ELISA). However, these methods have drawbacks such as complex operation, high cost, insufficient sensitivity, and difficulty in portability.

[0003] In recent years, electrochemical sensors have attracted widespread attention due to their high sensitivity, low cost, and ease of miniaturization. However, when detecting carbadoxime, existing electrochemical sensors still face challenges such as low sensitivity, poor selectivity, and insufficient catalytic performance. Therefore, there is an urgent need to develop highly sensitive, highly selective, and easy-to-use electrochemical sensors for the rapid detection of carbadoxime and its metabolites in food.

[0004] With the advancement of nanoscience and technology, atomic catalysts have garnered widespread attention in the field of electrochemical sensors due to their excellent catalytic performance and structural stability. Atomic catalysts are isolated metal atoms or diatomic or polyatomic clusters dispersed on a support material, each possessing a unique electronic structure and catalytic activity. Compared to traditional noble metal catalysts (such as Pt and Au), atomic catalysts are not only inexpensive but also enable highly selective detection of target molecules by manipulating their composition and coordination environment.

[0005] In electrochemical sensors, atomic catalysts are often used to accelerate the redox reactions of target molecules, thereby improving the sensitivity and response speed of the sensor. For example, electrochemical sensors based on single-atom or diatomic catalysts have been widely used in environmental monitoring, biomedical testing, and food safety. However, existing technologies still face some challenges: on the one hand, although traditional precious metal catalysts (such as Pt and Au nanoparticles) have high catalytic activity, they are expensive and prone to agglomeration, affecting long-term stability; on the other hand, single-component atomic catalysts have low selectivity in complex samples and are difficult to meet actual detection needs.

[0006] Currently, research on atomic catalysts for the detection of carbadoxime and its metabolites is relatively limited, and existing sensors still need to be further improved in terms of sensitivity, selectivity, and stability. Therefore, the development of highly sensitive and selective electrochemical sensors based on novel atomic or diatomic catalysts is of great significance for promoting the development of related fields. Summary of the Invention

[0007] (1) Technical issues to be resolved

[0008] In order to solve the above problems in the prior art, the present invention provides a method for constructing an electrochemical sensor based on a nitrogen-doped carbon-cobalt-nickel diatomic catalyst and its application.

[0009] (2) Technical solution

[0010] In order to achieve the above objectives, the main technical solutions adopted by the present invention include:

[0011] An electrochemical sensor based on a nitrogen-doped carbon-cobalt-nickel diatomic catalyst comprises: a glassy carbon electrode substrate whose surface is polished to a mirror finish; a CoNi / NC DAC active layer is provided on the glassy carbon electrode substrate, the CoNi / NC DAC active layer being uniformly loaded on the surface of the glassy carbon electrode, the active layer being composed of a nitrogen-doped carbon support and atomically dispersed cobalt-nickel bimetallic active sites; a sodium phosphate-stabilized interface is formed on the surface of the active layer; the sodium phosphate-stabilized interface is formed by scanning in a 0.1-0.5M Na3PO4 solution using differential pulse voltammetry.

[0012] A method for constructing an electrochemical sensor based on a nitrogen-doped carbon-cobalt-nickel diatomic catalyst comprises the following steps:

[0013] S1. Treat the glassy carbon electrode to make its surface reach the mirror standard;

[0014] S2, coating the dispersion containing nitrogen-doped carbon, cobalt, and nickel atom catalysts on the surface of the glassy carbon electrode and drying it under infrared light to obtain a CoNi / NC DAC modified electrode;

[0015] S3. The obtained CoNi / NC DAC modified electrode is placed in a Na3PO4 solution and scanned using differential pulse voltammetry to stabilize it, thereby forming an electrochemical sensor.

[0016] In the construction method as described above, preferably, in step S1, the glassy carbon electrode is treated by grinding γ-Al2O3 powder on a polishing cloth to a mirror surface, and placing it in a three-electrode system of potassium ferrocyanide solution, using cyclic voltammetry, and performing cyclic scanning in the potential range of -0.1V to 0.4V. When the peak potential difference of the cyclic voltammogram is less than 80mV, it meets the usage standard.

[0017] In the construction method described above, preferably, the particle size of the γ-Al2O3 powder is 0.05 μm, and the concentration of the potassium ferricyanide solution is 3 to 20 mmol / L.

[0018] In the construction method described above, preferably, in step S2, in the dispersion, the concentration of the nitrogen-doped carbon-cobalt-nickel atom catalyst is 5 mg / mL, and the dispersant is a 0.1% Nafion 117 solution.

[0019] In the construction method described above, preferably, in step S3, the concentration of the Na3PO4 solution is 0.05 to 2 mol / L. Furthermore, the concentration of the Na3PO4 solution is preferably 0.1 mol / L.

[0020] According to the above method, preferably, in step S3, the differential pulse voltammetry has an initial potential (Init E) of -0.65 V, an end potential (Final E) of -0.95 V, an amplitude of 0.01 V, an increment of 0.01 V, a pulse width of 0.06 seconds, a sampling width of 0.02 seconds, a pulse period of 0.5 seconds, a quiet time of 2 seconds, and a sensitivity of 1×10 -3 A / V.

[0021] Application of the electrochemical sensor or the electrochemical sensor obtained by the construction method described above in detecting carbadox.

[0022] Application of the electrochemical sensor or the electrochemical sensor obtained by the construction method described above in the preparation of a detection reagent for detecting carbadox.

[0023] A method for detecting carbadox, comprising:

[0024] The test solution is added to the electrolyte, the pH value is adjusted to alkaline, and an electrochemical measurement is performed using a three-electrode system under stirring conditions to obtain a peak current at a potential of -0.82 V; wherein the three-electrode system uses the electrochemical sensor described above or the electrochemical sensor prepared by the construction method described above as the working electrode, the titanium rod as the counter electrode, and the saturated calomel electrode as the reference electrode;

[0025] At the same time, carbadox standard solutions with different gradient concentrations were prepared and electrochemical measurements were performed according to the above-mentioned operation; a standard curve was plotted between the peak currents of the carbadox standard solutions with different gradient concentrations obtained at a potential of -0.82 V and their corresponding concentrations to obtain a standard curve equation;

[0026] Substitute the peak current of the test solution into the standard curve equation to obtain the concentration of carbadox in the test solution.

[0027] Furthermore, the gradient concentration of the carbadox standard solution is within the range of 10 to 500 nmol / L, and can be a 2-fold or 4-fold gradient dilution standard solution, or a standard solution of 500 nmol / L, 200 nmol / L, 100 nmol / L, 50 nmol / L, 20 nmol / L, or 10 nmol / L.

[0028] In a preferred embodiment, nitrogen is introduced for 10 minutes before detection to fully remove dissolved oxygen, the electrolyte is a Na3PO4 solution with a concentration of 0.05 to 2 mol / L, and the pH value is adjusted to 10 to 11.

[0029] In a preferred embodiment, the electrochemical determination is performed using differential pulse voltammetry with an initial potential (Init E) of -0.65 V, a final potential (Final E) of -0.95 V, an amplitude of 0.01 V, an increment of 0.01 V, a pulse width of 0.06 s, a sampling width of 0.02 s, a pulse period of 0.5 s, a quiet time of 2 s, and a sensitivity of 1 × 10 -3 A / V.

[0030] (3) Beneficial effects

[0031] The beneficial effects of the present invention are:

[0032] The present invention provides a method for constructing an electrochemical sensor based on a nitrogen-doped carbon-cobalt-nickel diatomic catalyst. The electrochemical sensor constructed by this method is modified with a nitrogen-doped carbon-cobalt-nickel diatomic catalyst. The Co-Ni diatomic site has a strong adsorption capacity for carbadoxide through the electron coupling effect, which increases the electron transfer efficiency and significantly improves the current response.

[0033] The electrochemical sensor constructed in the present invention based on a nitrogen-doped carbon-cobalt-nickel diatomic catalyst can be used to detect trace amounts of carbadoxime. The detection limit of carbadoxime is at the 3.1nM level, and the linear range of detection can cover 0.01μM to 100μM, meeting the detection requirements of carbadoxime in actual samples.

[0034] The carbadox detection method provided by the present invention overcomes the shortcomings of existing technologies, such as cumbersome methods and complex procedures. It significantly improves detection sensitivity, facilitates automation for low-concentration carbadox detection, and offers advantages in trace detection and interference resistance in complex samples. This electrochemical sensor can be used for food safety monitoring, such as rapid detection of carbadox residues in animal feed or meat. It can also be used for trace detection of nitrofuran drugs in water or soil, thus possessing a wide range of applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a transmission electron microscope (TEM) image of a nitrogen-doped carbon-cobalt-nickel diatomic catalyst;

[0036] Figure 2 For bare glassy carbon electrode and nitrogen-doped carbon cobalt nickel diatomic catalyst modified electrode at 1×10 -6 Differential pulse voltammogram in mol / L carbadoxime;

[0037] Figure 3 A graph showing peak currents of the electrochemical sensor prepared in the present invention when detecting standard solutions of carbadox with different concentrations;

[0038] Figure 4 A linear graph of peak current obtained by detecting carbadox standard solutions of different concentrations using the electrochemical sensor prepared by the present invention;

[0039] Figure 5 This is a diagram showing the detection results of the electrochemical sensor prepared in the present invention when different interfering substances are added. DETAILED DESCRIPTION

[0040] The electrochemical sensor provided by the present invention is made by modifying the surface of a glassy carbon electrode with a nitrogen-doped carbon-cobalt-nickel diatomic catalyst. This invention fully utilizes the excellent properties of this novel electrode-modifying material, demonstrating activity, high stability, and selectivity that differ from conventional nanocatalysts. The synergistic effect of the cobalt-nickel bimetallic center employed in the present invention demonstrates excellent catalytic performance, significantly enhancing electrochemical reaction activity and improving sensor sensitivity.

[0041] Extensive experimental research has revealed that the use of diatomic synergistic catalysis: Co-Ni diatomic sites enhance electron transfer efficiency through electronic coupling, significantly improving current response. Nitrogen-doped carbon supports: The high surface area and conductivity promote the exposure of active sites, while nitrogen atoms modulate the electronic structure of the metal center, further reducing the redox overpotential. Therefore, using nitrogen-doped carbon, cobalt, and nickel diatomic catalysts to modify glassy carbon electrodes can significantly improve the detection performance of electrochemical sensors.

[0042] The present invention provides a construction and application of an electrochemical sensor based on a nitrogen-doped carbon-cobalt-nickel diatomic catalyst. The electrochemical sensor is constructed by the following method:

[0043] (1) Treatment of glassy carbon electrodes

[0044] A glassy carbon electrode (diameter = 3 mm) was ground to a mirror surface using 0.05 μm γ-Al2O3 powder on a polishing cloth, washed with ultrapure water, and placed in a three-electrode system of 5 mM potassium ferrocyanide solution. Cyclic voltammetry was used to perform cyclic scanning in the potential range of -0.1 V to 0.4 V. When the peak potential difference of the cyclic voltammogram was less than 80 mV, it was proved that the electrode surface met the use requirements. It was then washed with ultrapure water and dried for later use.

[0045] (2) Nitrogen-doped carbon cobalt nickel atom catalyst (CoNi / NC DAC) modified electrode

[0046] Take 4 μL of nitrogen-doped carbon cobalt nickel atom catalyst (CoNi / NC DAC) dispersion, drop-coat it on the surface of glassy carbon electrode, and dry it under infrared light to obtain CoNi / NC DAC modified electrode.

[0047] (3) Construction of electrochemical sensors

[0048] The prepared working electrode was placed in a Na3PO4 solution of a certain concentration and scanned to stabilize it using differential pulse voltammetry. The initial potential (Init E) was -0.65 V, the final potential (Final E) was -0.95 V, the potential amplitude (Amplitude) was set to 0.01 V, the potential increment (Incr E) was 0.01 V, the pulse width (Pulse Width) was 0.06 s, the sampling width (Sampling width) was 0.02 s, the pulse period (Pulse period) was 0.5 s, the quiet time (Quiet Time) was 2 s, and the sensitivity (sensitivity) was set to 1×10 -3 A / V. The interval between two scans was 1 min, thus forming an electrochemical sensor.

[0049] Nitrogen-doped carbon-cobalt-nickel atomic catalysts are used. Compared with nanoparticle catalysts, nitrogen-doped carbon carriers effectively anchor metal atoms to avoid agglomeration or leaching, thus having better stability and reproducibility of electrochemical sensors.

[0050] The concentration of the Na3PO4 solution is preferably 0.1 mol / L. If the concentration is too low and the ionic strength is insufficient, the peak current will be low. If the concentration is further increased, the peak current will not increase significantly. Therefore, the concentration of the Na3PO4 solution is preferably 0.1 mol / L.

[0051] The specific application is the electrochemical detection of carbadoxime. The specific method is as follows:

[0052] A three-electrode system was used: the working electrode was a CoNi / NC DAC modified electrode, the counter electrode was a titanium rod, and the reference electrode was a saturated calomel electrode. Carbadoxime was detected in an electrolytic cell with a capacity of 40 mL, and 20 mL of electrolyte was loaded for each detection. The solution was stirred using an electromagnetic stirrer. The electrolyte was a Na3PO4 buffer solution, and the pH value was adjusted to alkaline using NaOH. Nitrogen was introduced for 10 minutes before use to fully remove dissolved oxygen.

[0053] In a preferred embodiment, the dosage of a 5 mg / mL nitrogen-doped carbon cobalt nickel atomic catalyst (CoNi / NC DAC) dispersion is preferably 4 μL. Excessively low or high catalyst dosages can reduce the electrocatalytic performance of the electrode. The electrolyte, a phosphate buffer solution (Na3PO4), has a regulatory effect and a high ionic strength for better response. The electrolyte is preferably adjusted to a pH of 11; excessively high or low pH values ​​can reduce the electrocatalytic performance of the electrode. The stirring rate is preferably 1200 rpm, as the stirring speed significantly affects the time required for the reaction to reach equilibrium and also affects the stability of the sensor membrane.

[0054] To better explain the present invention and facilitate understanding, the present invention is described in detail below in conjunction with the accompanying drawings through specific embodiments. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art. The reagents used in the following examples are all analytically pure and commercially available products can be used, such as carbadoxime standards can be purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., and nitrogen-doped carbon cobalt nickel atom catalyst can be purchased from Jiangsu Xianfeng Nanomaterial Technology Co., Ltd.

[0055] Example 1

[0056] A method for constructing a nitrogen-doped carbon-cobalt-nickel diatomic catalyst electrochemical sensor for detecting trace amounts of carbadoxime comprises the following steps:

[0057] (1) Treatment of glassy carbon electrodes

[0058] A glassy carbon electrode (diameter = 3 mm) was ground to a mirror surface on a polishing cloth using γ-Al2O3 powder with a particle size of 0.05 μm, washed with ultrapure water, and placed in a three-electrode system of 5 mM potassium ferrocyanide solution. The three-electrode system consisted of a glassy carbon electrode as the working electrode, a saturated calomel electrode as the reference electrode, and a titanium rod as the auxiliary electrode. Cyclic voltammetry was used to perform cyclic scanning in the potential range of -0.1 V to 0.4 V. When the peak potential difference of the cyclic voltammogram was less than 80 mV, it was proved that the electrode surface met the use requirements. The electrode was washed with ultrapure water and dried for later use.

[0059] (2) Nitrogen-doped carbon cobalt nickel atom catalyst (CoNi / NC DAC) modified electrode

[0060] Nitrogen-doped carbon cobalt nickel atom catalyst (CoNi / NC DAC) can be purchased from Jiangsu Xianfeng Nanomaterial Technology Co., Ltd., and its microstructure transmission electron microscopy results are shown in Figure 2. Figure 1 As shown, the catalyst, which appears as uneven flakes, was prepared by dispersing the nitrogen-doped carbon, cobalt, and nickel atoms in a 0.1% Nafion 117 solution to create a 5 mg / mL dispersion. Nafion 117 solution is available from Shanghai Aladdin Biochemical Technology Co., Ltd. Four microliters of this 5 mg / mL CoNi / NC DAC dispersion was applied to the surface of a glassy carbon electrode and dried under infrared light to obtain a CoNi / NC DAC-modified electrode.

[0061] (3) Construction of electrochemical sensors

[0062] The prepared working electrode was placed in a 0.1 mol / L Na3PO4 solution and scanned to stabilize it using differential pulse voltammetry. The initial potential (Init E) was -0.65 V, the final potential (Final E) was -0.95 V, the potential amplitude (Amplitude) was set to 0.01 V, the potential increment (Incr E) was 0.01 V, the pulse width (Pulse Width) was 0.06 s, the sampling width (Sampling width) was 0.02 s, the pulse period (Pulse period) was 0.5 s, the quiet time (Quiet Time) was 2 s, and the sensitivity (sensitivity) was set to 1×10 -3 A / V. The interval between the two scans was 1 min, and the CoNi / NC DAC electrochemical sensor was formed.

[0063] Example 2 Differential Pulse Voltammetry Characterization of the Electrochemical Sensor for Detecting Trace Carbadox According to the Present Invention

[0064] Since the pores in the membrane can serve as channels for electron transfer, the surface properties of various electrodes are characterized by the magnitude of their current. In a three-electrode system, the CoNi / NC DAC electrochemical sensor prepared as in Example 1 was used as the working electrode, the titanium rod was used as the counter electrode, and the saturated calomel electrode was used as the reference electrode. At the same time, a glassy carbon electrode without any treatment was used as the working electrode for comparison. Differential pulse voltammetry was used to scan a 1.0 μmol / L carbadox solution. The initial potential (Init E) was -0.65 V, the final potential (Final E) was -0.95 V, the potential amplitude (Amplitude) was set to 0.01 V, the potential increment (IncrE) was 0.01 V, the pulse width (Pulse Width) was 0.06 s, the sampling width (Sampling width) was 0.02 s, the pulse period (Pulse period) was 0.5 s, the quiet time (Quiet Time) was 2 s, and the sensitivity (sensitivity) was set to 1×10 -3 A / V.

[0065] The results are as follows Figure 2 As shown, on the glassy carbon electrode, 1.0 μmol / L carbadoxime only exhibited an extremely weak reduction peak at -0.82 V, with a peak current of 2.77 μA. On the CoNi / NC DAC-modified electrode prepared according to Example 1 (denoted as the working electrode in the figure), the same concentration of carbadoxime (20.0 μmol / L) exhibited a very strong reduction peak at -0.82 V, with a peak current of 81.4 μA. Compared to the glassy carbon electrode, the peak current of carbadoxime on the CoNi / NC DAC-modified electrode increased nearly 30-fold, demonstrating excellent electrocatalytic performance and enabling highly sensitive detection of carbadoxime.

[0066] Example 3 Electrochemical Detection of Carbadox

[0067] A three-electrode system was used: the working electrode was a CoNi / NC DAC electrochemical sensor, the counter electrode was a titanium rod, and the reference electrode was a saturated calomel electrode. Carbadoxime was detected in an electrolytic cell with a capacity of 40 mL, and 20 mL of electrolyte was loaded for each detection. The electromagnetic stirrer was stirred at 1200 rpm. The electrolyte was a Na3PO4 buffer solution, and the pH value was adjusted to 11 with NaOH. Nitrogen was introduced for 10 minutes before use to fully remove dissolved oxygen. An appropriate volume of carbadox stock solution was added to the electrolyte to prepare carbadox standard solutions with concentrations of 10, 20, 50, 100, 200, and 500 nmol / L, respectively. Differential pulse voltammetry was used to scan the solutions, with an initial potential (Init E) of -0.65 V, a final potential (Final E) of -0.95 V, an amplitude of 0.01 V, an increment of 0.01 V, a pulse width of 0.06 s, a sampling width of 0.02 s, a pulse period of 0.5 s, a quiet time of 2 s, and a sensitivity of 1 × 10 -3 A / V. In the same carbadox standard solution, the potential is used as the horizontal axis and the peak current at different potentials is used as the vertical axis to draw a curve. The obtained curve is as follows Figure 3 At a potential of -0.82 V, the peak currents of different carbadox standard solutions were plotted with the concentration of carbadox as the horizontal axis and the peak currents measured at different concentrations as the vertical axis. The results are shown in Figure 2. Figure 4 As shown, in the range of 10 to 500 nmol / L, the peak current and the carbadox concentration showed a good linear relationship, and the linear regression equation was I (μA) = 0.12C (nmol / L) + 1.68, with a correlation coefficient of 0.9985 and a detection limit of 3.1 nmol / L (S / N = 3). A highly sensitive electrochemical detection method for carbadox can be established, where I represents the current and C represents the concentration.

[0068] Example 4 Anti-interference experiment

[0069] As in the test method of Example 3, the carbadox concentration was fixed at 500 nmol / L, and the peak current value was measured using differential pulse voltammetry. The average of multiple measurements was recorded as I0. Interfering substances such as glucose, urea, uric acid, creatinine, potassium chloride, sodium chloride, and calcium chloride were added to carbadox, and the peak current value was measured using differential pulse voltammetry, recorded as I. The ratio of the peak current value measured in the carbadox solution containing different interfering substances to the peak current value measured in the carbadox solution without adding interfering substances, I / I0, was plotted as a bar graph. The results are shown in Figure 2. Figure 5As shown in the results, it can be seen that 1000 times the concentration of glucose, urea, uric acid and 100 times the concentration of creatinine, K + 、Na + , Ca 2+ There is no interference with it, indicating that the sensor has excellent anti-interference ability.

[0070] Example 5 Actual sample measurement

[0071] Fresh chicken or pork samples were selected, homogenized with water, and filtered. 200 μL of the filtrate was added to 20 mL of PBS, and carbadox was added to make the final concentrations 20 nmol / L, 50 nmol / L, and 100 nmol / L. Differential pulse voltammetry was performed according to Example 3, with a starting potential of -0.65 V, a termination potential of -0.95 V, a potential amplitude of 0.01 V, a potential increment of 0.01 V, a pulse width of 0.06 s, a sampling width of 0.02 s, a pulse period of 0.5 s, a resting time of 2 s, and a sensitivity of 1×10 -3 The peak currents measured at different carbadox spiked concentrations were substituted into the standard curve to obtain the measured concentrations. The recovery rate was calculated by dividing the measured concentration by the spiked concentration by 100%. The results are shown in Table 1.

[0072] Table 1 Test results of spiked samples (n=5)

[0073]

[0074] Table 1 shows that the recoveries of the method ranged from 86.97% to 115.37%, and the relative standard deviations ranged from 1.53% to 4.34%. The results indicate that the prepared electrochemical sensor can be used for the quantitative analysis of carbadox in actual samples with accurate detection results.

[0075] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other manner. Any person skilled in the art may utilize the above-disclosed technical content to modify or modify the above-disclosed embodiments into equivalent embodiments. However, any simple modifications, equivalent variations, and modifications to the above-disclosed embodiments that do not depart from the technical content of the present invention and are based on the technical essence of the present invention shall remain within the scope of protection of the present invention.

Claims

1. An electrochemical sensor based on nitrogen-doped carbon-cobalt-nickel diatomic catalyst, characterized in that: include: A glassy carbon electrode substrate with a surface polished to a mirror finish; A CoNi / NC DAC active layer is provided on the glassy carbon electrode substrate. The CoNi / NC DAC active layer is uniformly loaded on the surface of the glassy carbon electrode. The active layer is composed of a nitrogen-doped carbon support and atomically dispersed cobalt-nickel bimetallic active sites. A sodium phosphate-stabilized interface is formed on the surface of the active layer. The sodium phosphate-stabilized interface is formed by scanning in a 0.1-0.5M Na3PO4 solution using differential pulse voltammetry.

2. A method for constructing an electrochemical sensor based on nitrogen-doped carbon-cobalt-nickel diatomic catalyst, characterized in that: It includes the following steps: S1. Treat the glassy carbon electrode to make its surface reach the mirror standard; S2, coating the dispersion containing nitrogen-doped carbon, cobalt, and nickel atom catalysts on the surface of the glassy carbon electrode and drying it under infrared light to obtain a CoNi / NC DAC modified electrode; S3. The obtained CoNi / NC DAC modified electrode is placed in a Na3PO4 solution and scanned using differential pulse voltammetry to stabilize it, thereby forming an electrochemical sensor.

3. The construction method according to claim 2, wherein: In step S1, the treatment of the glassy carbon electrode includes: grinding the glassy carbon electrode to a mirror surface using γ-Al2O3 powder on a polishing cloth, placing it in a three-electrode system of potassium ferrocyanide solution, using cyclic voltammetry, and performing cyclic scanning in the potential range of -0.1V to 0.4V. When the peak potential difference of the cyclic voltammogram is less than 80mV, it meets the usage standard; wherein, the particle size of the γ-Al2O3 powder is 0.05μm, and the concentration of the potassium ferrocyanide solution is 3 to 20mmol / L.

4. The construction method according to claim 2, wherein: In step S2, in the dispersion, the concentration of the nitrogen-doped carbon-cobalt-nickel atom catalyst is 5 mg / mL, and the dispersant is 0.1% Nafion 117 solution.

5. The construction method according to claim 2, wherein: In step S3, the concentration of the Na3PO4 solution is 0.05-2 mol / L.

6. The construction method according to claim 2, wherein: In step S3, the differential pulse voltammetry was performed with a starting potential of -0.65 V, an ending potential of -0.95 V, a potential amplitude of 0.01 V, a potential increment of 0.01 V, a pulse width of 0.06 s, a sampling width of 0.02 s, a pulse period of 0.5 s, a resting time of 2 s, and a sensitivity of 1 × 10 -3 A / V.

7. Use of the electrochemical sensor according to claim 1 or the electrochemical sensor obtained by the construction method according to any one of claims 2 to 6 in detecting carbadox.

8. Use of the electrochemical sensor according to claim 1 or the electrochemical sensor obtained by the construction method according to any one of claims 2 to 6 in preparing a detection reagent for detecting carbadox.

9. A method for detecting carbadox, characterized in that: The test solution is added to the electrolyte, the pH value is adjusted to alkaline, and an electrochemical measurement is performed using a three-electrode system under stirring conditions to obtain a peak current at a potential of -0.82 V; wherein the three-electrode system comprises an electrochemical sensor according to claim 1 or an electrochemical sensor prepared by the construction method according to any one of claims 2 to 6 as a working electrode, a titanium rod as a counter electrode, and a saturated calomel electrode as a reference electrode; At the same time, electrochemical determination was performed on carbadox standard solutions with different gradient concentrations according to the above operation; a standard curve was plotted between the peak currents of the carbadox standard solutions with different gradient concentrations obtained at a potential of -0.82 V and their corresponding concentrations to obtain a standard curve equation; Substitute the peak current of the test solution into the standard curve equation to obtain the concentration of carbadox in the test solution.

10. The method for detecting carbadox according to claim 9, wherein: Nitrogen was introduced for 10 min before testing to fully remove dissolved oxygen. The electrolyte was a Na3PO4 solution with a concentration of 0.05 to 2 mol / L. The pH was adjusted to 10 to 11. Electrochemical determinations were performed using differential pulse voltammetry with a starting potential of -0.65 V, an end potential of -0.95 V, a potential amplitude of 0.01 V, a potential increment of 0.01 V, a pulse width of 0.06 s, a sampling width of 0.02 s, a pulse period of 0.5 s, a rest time of 2 s, and a sensitivity of 1 × 10 -3 A / V.

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