A method for constructing an electrochemical sensor based on nitrogen-doped carbon cobalt-nickel diatomic catalyst and application thereof

Abstract

The present application relates to a kind of construction method of electrochemical sensor based on nitrogen-doped carbon cobalt nickel diatomic catalyst and its application, the electrochemical sensor is the composite material after nitrogen-doped carbon cobalt nickel diatomic catalyst is mixed with film-forming material is made on the surface of glassy carbon electrode and is prepared.The electrochemical sensor provided by the present application has high stability and selectivity, double metal center synergistic effect, shows excellent catalytic performance, significantly improves electrochemical reaction activity, and improves the sensitivity of sensor.The electrochemical sensor is used to detect carbazochrome, and has high detection sensitivity and response speed, especially in trace detection and complex sample anti-interference aspect has advantage.The present application can be applied to food safety monitoring, such as rapid detection of carbazochrome residue in animal feed or meat, and can also be used for trace detection of nitrofurans in water or soil, and has wide application prospect.

Description

TECHNICAL FIELD

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

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

[0003] In recent years, electrochemical sensors have received widespread attention due to their high sensitivity, low cost, and ease of miniaturization. However, in the detection of carbadox, existing electrochemical sensors still face problems such as low detection sensitivity, poor selectivity, and insufficient catalytic performance. Therefore, there is an urgent need to develop an electrochemical sensor with high sensitivity, high selectivity, and simple operation for rapid detection of carbadox and its metabolites in food.

[0004] With the development of nanoscience and technology, atomic catalysts have received extensive attention in the field of electrochemical sensors due to their excellent catalytic performance and structural stability. Atomic catalysts refer to isolated metal atoms or diatomic, multi-atomic clusters dispersed on support materials, which have unique electronic structures and catalytic activity. Compared with traditional noble metal catalysts (such as Pt, Au), atomic catalysts not only have low cost, but also can achieve highly selective detection of target molecules by adjusting their composition and coordination environment.

[0005] In electrochemical sensors, atomic catalysts are often used to accelerate the redox reaction 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 detection, and food safety, etc. However, existing technologies still face some challenges: on the one hand, traditional noble metal catalysts (such as Pt, Au nanoparticles) have high catalytic activity, but their cost is high and they are prone to aggregation, affecting long-term stability; on the other hand, single-component atomic catalysts have low selectivity in complex samples, making it difficult to meet the actual detection requirements.

[0006] Current research on the use of atomic catalysts in the detection of carbazone and its metabolites remains limited, and existing sensors still require further improvement in sensitivity, selectivity, and stability. Therefore, developing a highly sensitive and selective electrochemical sensor based on novel atomic or diatomic catalysts is of great significance for advancing this field. Summary of the Invention

[0007] (a) Technical problems to be solved

[0008] To address the aforementioned problems in the prior art, this invention provides a method for constructing an electrochemical sensor based on a nitrogen-doped carbon-cobalt-nickel diatom catalyst and its application.

[0009] (II) Technical Solution

[0010] 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 biatom catalyst includes: a glassy carbon electrode substrate with a surface polished to a mirror finish; a CoNi / NC DAC active layer uniformly loaded on the glassy carbon electrode substrate, the active layer being composed of a nitrogen-doped carbon support and atomically dispersed cobalt-nickel bimetallic active sites; and a sodium phosphate stabilization interface formed on the surface of the active layer; the sodium phosphate stabilization interface is formed by scanning in a 0.1–0.5 M Na3PO4 solution using differential pulse voltammetry.

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

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

[0014] S2. The dispersion containing nitrogen-doped carbon, cobalt, and nickel atoms catalyst is coated on the surface of glassy carbon electrode and dried under infrared light to obtain CoNi / NC DAC modified electrode.

[0015] S3. The obtained CoNi / NC DAC modified electrode is placed in Na3PO4 solution and stabilized by differential pulse voltammetry, thus forming an electrochemical sensor.

[0016] In the construction method described above, preferably, in step S1, the glassy carbon electrode is treated by grinding γ-Al2O3 powder on a polishing cloth to a mirror finish, and then placing it in a three-electrode system of potassium ferricyanide solution. Cyclic voltammetry is used to perform cyclic scanning within a potential range of -0.1V to 0.4V. When the peak potential difference of the cyclic voltammogram is less than 80mV, the standard for use is met.

[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 3–20 mmol / L.

[0018] In the construction method described above, preferably, in step S2, the concentration of nitrogen-doped carbon, cobalt, and nickel atom catalyst in the dispersion 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 0.05–2 mol / L. More preferably, the concentration of the Na3PO4 solution is 0.1 mol / L.

[0020] Preferably, in step S3, the differential pulse voltammetry method has an initial potential (Init E) of -0.65V, a final potential (Final E) of -0.95V, a potential amplitude of 0.01V, a potential increment (IncrE) of 0.01V, 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 1×10⁻⁶. -3 A / V.

[0021] Application of electrochemical sensors or electrochemical sensors obtained by the methods described above in the detection of carbazone.

[0022] The application of electrochemical sensors or electrochemical sensors obtained by the methods described above in the preparation of detection reagents for detecting carbamate.

[0023] A method for detecting carbaryl, comprising:

[0024] The test solution was added to the electrolyte, and the pH was adjusted to alkaline. Electrochemical measurement was performed using a three-electrode system under stirring conditions to obtain the peak current at a potential of -0.82V. In the three-electrode system, the electrochemical sensor described above or the electrochemical sensor prepared by the above construction method 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.

[0025] Meanwhile, carba oxygen standard solutions with different gradient concentrations were prepared, and electrochemical measurements were performed according to the above procedure; standard curves were plotted with the peak currents of carba oxygen standard solutions with different gradient concentrations obtained at a potential of -0.82V and their corresponding concentrations to obtain the standard curve equation.

[0026] Substituting the peak current of the test solution into the standard curve equation yields the concentration of carba oxygen in the test solution.

[0027] Furthermore, the carba oxygen standard solutions with gradient concentrations in the range of 10–500 nmol / L can be standard solutions with 2-fold or 4-fold serial dilutions, or standard solutions with concentrations of 500 nmol / L, 200 nmol / L, 100 nmol / L, 50 nmol / L, 20 nmol / L, and 10 nmol / L.

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

[0029] In a preferred embodiment, the electrochemical measurement is performed using differential pulse voltammetry, with an initiation potential (Init E) of -0.65V, a final potential (Final E) of -0.95V, an amplitude of 0.01V, an increment of 0.01V, 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 1×10⁻⁶. -3 A / V.

[0030] (III) Beneficial Effects

[0031] The beneficial effects of this invention are:

[0032] This 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 sites have a strong adsorption capacity for carba oxygen through electronic coupling effect, which increases electron transfer efficiency and significantly improves current response.

[0033] The present invention constructs an electrochemical sensor based on a nitrogen-doped carbon-cobalt-nickel diatomic catalyst. This electrochemical sensor can be used to detect trace amounts of carba oxygen. The detection limit of carba oxygen is on the order of 3.1 nM, and the linear detection range can cover 0.01 μM to 100 μM, which meets the detection requirements of carba oxygen in actual samples.

[0034] The carbamate detection method provided by this invention overcomes the shortcomings of existing technologies, such as overly cumbersome methods and complex procedures, and significantly improves detection sensitivity. It is easily automated for detecting low concentrations of carbamate, and exhibits superior advantages, particularly in trace detection and resistance to interference from complex samples. This electrochemical sensor can be used for rapid detection of carbamate residues in animal feed or meat, and for food safety monitoring; it can also be used for trace detection of nitrofurans in water or soil, demonstrating a wide range of applications. Attached Figure Description

[0035] Figure 1 Transmission electron microscopy (TEM) image of a nitrogen-doped carbon-cobalt-nickel diatom catalyst;

[0036] Figure 2 For bare glassy carbon electrodes and nitrogen-doped carbon-cobalt-nickel diatom catalyst-modified electrodes at 1×10 -6 Differential pulse voltammogram of mol / L carba oxygen;

[0037] Figure 3 The graph shows the peak current detected by the electrochemical sensor prepared in this invention for standard solutions of carba oxygen at different concentrations.

[0038] Figure 4 Linear graphs of peak currents obtained by the electrochemical sensor prepared in this invention for detecting carba oxygen standard solutions of different concentrations;

[0039] Figure 5 The image shows the detection results of the electrochemical sensor prepared in this invention when different interfering substances are added. Detailed Implementation

[0040] The electrochemical sensor provided by this invention is prepared by modifying a nitrogen-doped carbon-cobalt-nickel biatom catalyst onto the surface of a glassy carbon electrode. This invention fully utilizes the superior properties of this novel electrode modification material, exhibiting activity, high stability, and selectivity distinct from conventional nanocatalysts. The synergistic effect of the cobalt-nickel bimetallic center used in this invention demonstrates excellent catalytic performance, significantly improving electrochemical reaction activity and enhancing sensor sensitivity.

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

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

[0043] (1) Treatment of glassy carbon electrode

[0044] The glassy carbon electrode (diameter = 3 mm) was polished to a mirror finish on a polishing cloth using 0.05 μm γ-Al2O3 powder. It was then washed with ultrapure water and placed in a three-electrode system containing 5 mM potassium ferricyanide solution. Cyclic voltammetry was used to perform cyclic scanning within a 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 determined that the electrode surface met the requirements for use. The electrode was then washed with ultrapure water and dried for later use.

[0045] (2) Electrode modified with nitrogen-doped carbon cobalt nickel atom catalyst (CoNi / NC DAC)

[0046] Take 4 μL of nitrogen-doped carbon cobalt nickel atom catalyst (CoNi / NC DAC) dispersion, drop it onto the surface of a glassy carbon electrode, and dry it under infrared light to obtain the 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 stabilized using differential pulse voltammetry. The initial potential (Init E) was -0.65V, the final potential (Final E) was -0.95V, the amplitude was set to 0.01V, the increment (Incr E) was 0.01V, the pulse width was 0.06 seconds, the sampling width was 0.02 seconds, the pulse period was 0.5 seconds, the rest time was 2 seconds, and the sensitivity was set to 1×10⁻⁶. -3 A / V. An interval of 1 minute is set between two scans to form an electrochemical sensor.

[0049] Compared to nanoparticle catalysts, nitrogen-doped carbon, cobalt, and nickel atomic catalysts effectively anchor metal atoms, preventing aggregation or leaching, thus exhibiting better stability and reproducibility in electrochemical sensors.

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

[0051] The specific application is the electrochemical detection of carbazone, and 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; carba oxygen was detected in an electrolytic cell; the volume of the electrolytic cell was 40 mL, and the electrolyte volume was 20 mL for each test; the system was stirred with an electromagnetic stirrer; the electrolyte was a Na3PO4 buffer solution, and the pH was adjusted to alkalinity using NaOH; nitrogen gas was purged for 10 min before use to completely remove dissolved oxygen.

[0053] In a preferred embodiment, the amount of the 5 mg / mL nitrogen-doped carbon cobalt nickel atomic catalyst (CoNi / NC DAC) dispersion is preferably 4 μL. Too low or too high a catalyst concentration will reduce the electrocatalytic performance of the electrode. The electrolyte, a phosphate buffer (Na3PO4), has a regulating effect, providing higher ionic strength for better response. The electrolyte is preferably adjusted to pH = 11; too high or too low a pH will 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 and facilitate understanding of the present invention, a detailed description of the invention is provided below with reference to the accompanying drawings and specific embodiments. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art. All reagents used in the following examples are analytical grade and can be commercially available products. For example, carbazone standard can be purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., and nitrogen-doped carbon, cobalt, and nickel atom catalysts can be purchased from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd.

[0055] Example 1

[0056] A method for constructing a nitrogen-doped carbon-cobalt-nickel diatom catalyst electrochemical sensor for detecting trace amounts of carba oxygen, comprising the following steps:

[0057] (1) Treatment of glassy carbon electrode

[0058] A glassy carbon electrode (diameter = 3 mm) was polished to a mirror finish on a polishing cloth using γ-Al₂O₃ powder with a particle size of 0.05 μm. After washing with ultrapure water, it was placed in a three-electrode system containing a 5 mM potassium ferricyanide solution. The glassy carbon electrode was used as the working electrode, the saturated calomel electrode as the reference electrode, and the titanium rod as the auxiliary electrode. Cyclic voltammetry was used to perform cyclic scanning within a 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 determined that the electrode surface met the requirements for use. The electrode was then washed with ultrapure water and dried for later use.

[0059] (2) Electrode modified with nitrogen-doped carbon cobalt nickel atom catalyst (CoNi / NC DAC)

[0060] Nitrogen-doped carbon-cobalt-nickel atom catalyst (CoNi / NC DAC) was available from Jiangsu Xianfeng Nanomaterials Technology Co., Ltd., and its microstructure transmission electron microscopy results are as follows: Figure 1 As shown, the nitrogen-doped carbon cobalt nickel atom catalyst, in the form of uneven flakes, was dispersed in a 0.1% Nafion 117 solution to prepare a 5 mg / mL dispersion. The Nafion 117 solution was available from Shanghai Aladdin Biochemical Technology Co., Ltd. 4 μL of the 5 mg / mL CoNi / NC DAC dispersion was coated onto the surface of a glassy carbon electrode and dried under infrared light to obtain the 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 stabilized using differential pulse voltammetry. The initial potential (Init E) was -0.65 V, the final potential (Final E) was -0.95 V, the amplitude was 0.01 V, the increment (Incr E) was 0.01 V, the pulse width was 0.06 seconds, the sampling width was 0.02 seconds, the pulse period was 0.5 seconds, the rest time was 2 seconds, and the sensitivity was 1 × 10⁻⁶. -3 A / V. A 1-minute interval between two scans is required to form the CoNi / NC DAC electrochemical sensor.

[0063] Example 2: Differential pulse voltammetry characterization of the electrochemical sensor for detecting trace amounts of carba oxygen described in this invention.

[0064] Since the pores in the membrane can serve as channels for electron transfer, the surface properties of various electrodes can be characterized based on the magnitude of their current. In the three-electrode system, the CoNi / NC DAC electrochemical sensor prepared as in Example 1 was used as the working electrode, a titanium rod as the counter electrode, and a saturated calomel electrode as the reference electrode. An untreated glassy carbon electrode was also used as the working electrode for comparison. Differential pulse voltammetry was used to scan a 1.0 μmol / L carba oxygen solution with the following settings: initial potential (Init E) -0.65 V, final potential (Final E) -0.95 V, amplitude (Amplitude) 0.01 V, increment (IncrE) 0.01 V, pulse width (Pulse Width) 0.06 s, sampling width 0.02 s, pulse period 0.5 s, quiet time 2 s, and sensitivity 1 × 10⁻¹⁰. -3 A / V.

[0065] The results are as follows Figure 2 As shown, on the glassy carbon electrode, 1.0 μmol / L carbazone exhibits only a very 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 carbazone (20.0 μmol / L) shows a very strong reduction peak at -0.82 V, with a peak current of 81.4 μA. Compared with the glassy carbon electrode, the peak current of carbazone on the CoNi / NC DAC-modified electrode increases by nearly 30 times, demonstrating superior electrocatalytic performance and enabling highly sensitive detection of carbazone.

[0066] Example 3: Electrochemical detection of carbamate

[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; carba oxygen was detected in an electrolytic cell; the volume of the electrolytic cell was 40 mL, and the electrolyte volume was 20 mL for each detection; the electromagnetic stirrer was used for stirring at 1200 rpm; the electrolyte was a Na3PO4 buffer solution, and the pH was adjusted to 11 using NaOH; nitrogen gas was purged for 10 min before use to completely remove dissolved oxygen. Add an appropriate volume of carba oxygen stock solution to the electrolyte to prepare carba oxygen standard solutions with concentrations of 10, 20, 50, 100, 200, and 500 nmol / L, respectively. Differential pulse voltammetry was used to scan these solutions, with the following settings: initial potential (Init E) -0.65 V, final potential (Final E) -0.95 V, amplitude (Amplitude) 0.01 V, increment (Incr E) 0.01 V, pulse width (Pulse Width) 0.06 s, sampling width (Sampling Width) 0.02 s, pulse period 0.5 s, quiet time 2 s, and sensitivity 1 × 10⁻⁶. -3 A / V. Using the same carbazone standard solution, a curve was plotted with potential as the x-axis and peak current at different potentials as the y-axis. The resulting curve is shown below. Figure 3 As shown in the figure. At a potential of -0.82V, the peak currents of different carbazone standard solutions were measured, and a curve was plotted with the carbazone concentration as the x-axis and the corresponding peak currents at different concentrations as the y-axis. The results are shown in the figure. Figure 4 As shown, within the range of 10–500 nmol / L, the peak current exhibits a good linear relationship with the carba oxygen concentration. The linear regression equation is 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 carba oxygen can be established, where I represents the current and C represents the concentration.

[0068] Example 4 Anti-interference test

[0069] As in Example 3, the concentration of carba oxygen was fixed at 500 nmol / L. The peak current value was measured using differential pulse voltammetry, and 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 carba oxygen, and the peak current value was measured using differential pulse voltammetry, recorded as I. A bar chart was plotted showing the ratio I / I0 between the peak current values ​​measured in carba oxygen solutions containing different interfering substances and those measured in carba oxygen solutions without added interfering substances. The results are as follows: Figure 5As shown in the results, 1000 times the concentration of glucose, urea, and uric acid, and 100 times the concentration of creatinine and potassium... + Na + Ca 2+ The sensor exhibits excellent anti-interference capabilities as there are no interfering objects.

[0070] Example 5: Actual Sample Measurement

[0071] Fresh chicken or pork samples were selected, homogenized with water, filtered, and 200 μL of the filtrate was added to 20 mL of PBS. Carba oxygen was added to achieve final concentrations of 20 nmol / L, 50 nmol / L, and 100 nmol / L. Differential pulse voltammetry was performed according to Example 3, with an onset 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 seconds, a sampling width of 0.02 seconds, a pulse period of 0.5 seconds, a resting time of 2 seconds, and a sensitivity of 1 × 10⁻⁶. -3 A / V. The peak currents measured at different carba oxygen spiking concentrations were substituted into the standard curve to obtain the measured concentrations. The recovery rate was obtained by multiplying the measured concentration by the spiking 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 recovery rate of the method ranges from 86.97% to 115.37%, and the relative standard deviation is 1.53% to 4.34%. The results indicate that the prepared electrochemical sensor can be used for the quantitative analysis of carba oxygen in real samples, and the detection results are accurate.

[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 way. Any person skilled in the art can make changes or modifications to the above-disclosed technical content to create equivalent embodiments. However, any simple modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the protection scope of the present invention.

Claims

1. A carba-oxygen electrochemical sensor based on a nitrogen-doped carbon-cobalt-nickel diatom 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 disposed 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 stabilization interface is formed on the surface of the active layer. The sodium phosphate stabilization interface is formed by scanning in a 0.1~0.5M Na3PO4 solution using differential pulse voltammetry.

2. A method for constructing a carba-oxygen electrochemical sensor based on a nitrogen-doped carbon-cobalt-nickel diatom catalyst, characterized in that, It includes the following steps: S1. Treat the glassy carbon electrode to make its surface reach the mirror standard; S2. The dispersion containing nitrogen-doped carbon, cobalt, and nickel atoms catalyst is coated on the surface of glassy carbon electrode and dried under infrared light to obtain CoNi / NC DAC modified electrode. S3. The obtained CoNi / NC DAC modified electrode is placed in Na3PO4 solution and stabilized by differential pulse voltammetry, thus forming an electrochemical sensor.

3. The construction method as described in claim 2, characterized in that, In step S1, the treatment of the glassy carbon electrode includes: grinding the glassy carbon electrode to a mirror finish on a polishing cloth using γ-Al2O3 powder, and placing it in a three-electrode system of potassium ferricyanide solution. Cyclic voltammetry is used to perform cyclic scanning within a potential range of -0.1 V to 0.4 V. When the peak potential difference of the cyclic voltammogram is less than 80 mV, the standard for use is met. 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.

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

5. The construction method as described in claim 2, characterized in that, In step S3, the concentration of the Na3PO4 solution is 0.1 ~ 0.5 mol / L.

6. The construction method as described in claim 2, characterized in that, In step S3, the differential pulse voltammetry method has an initial potential of -0.65 V, an initial 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 seconds, a sampling width of 0.02 seconds, a pulse period of 0.5 seconds, a rest time of 2 seconds, and a sensitivity of 1×10⁻⁶. -3 A / V.

7. The application of the electrochemical sensor of claim 1 or the electrochemical sensor obtained by the construction method of any one of claims 2-6 in the detection of carba oxygen.

8. The application of the electrochemical sensor according to claim 1 or the electrochemical sensor obtained by the construction method of any one of claims 2-6 in the preparation of a detection reagent for detecting carbamate.

9. A method for detecting carbazone, characterized in that, The test solution was added to the electrolyte, and the pH was adjusted to alkaline. Electrochemical measurement was performed using a three-electrode system under stirring conditions to obtain the peak current at a potential of -0.82 V. In the three-electrode system, the electrochemical sensor as described in claim 1 or the electrochemical sensor prepared by the construction method described in any one of claims 2-6 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. Meanwhile, carba oxygen standard solutions of different gradient concentrations were electrochemically measured according to the above procedure; the peak currents of carba oxygen standard solutions of different gradient concentrations obtained at a potential of -0.82 V were plotted with their corresponding concentrations to obtain the standard curve equation. Substituting the peak current of the test solution into the standard curve equation yields the concentration of carba oxygen in the test solution.

10. The detection method for carbazone as described in claim 9, characterized in that, Before detection, nitrogen gas was purged for 10 min to completely remove dissolved oxygen. The electrolyte was a Na3PO4 solution with a concentration of 0.05–2 mol / L; the pH was adjusted to 10–11. Electrochemical measurements were performed using differential pulse voltammetry, with an onset 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 seconds, a sampling width of 0.02 seconds, a pulse period of 0.5 seconds, a rest time of 2 seconds, and a sensitivity of 1 × 10⁻⁶. -3 A / V.

Images