Copper-based nanocarbon nitride materials, synthesis methods, and methods of electrochemically detecting perfluoro- and polyfluoroalkyl substances

Abstract

The application belongs to the technical field of perfluoro and polyfluoro alkyl compound detection, and specifically discloses a copper-based nano-carbon nitride material, a synthesis method and a method for electrochemically detecting perfluoro and polyfluoro alkyl compounds. The detection method comprises the following steps: S21, respectively configuring standard solutions containing different concentrations of perfluoro and polyfluoro alkyl compounds; S22, configuring a copper-based nano-carbon nitride material solution, and uniformly coating the material solution on the surface of an electrode; S23, using a three-electrode system and an electrochemical workstation to respectively measure the volt-ampere characteristic curves of the standard solutions with different concentrations; and S24, fitting the measurement data, so as to realize the detection of the concentrations of perfluoro and polyfluoro alkyl compounds according to the peak current change. The copper-based nano-carbon nitride material prepared by the application has a high copper loading amount, more determined Cu atomic active sites and a high specific surface area. The material is applied to electrochemically detect perfluoro and polyfluoro alkyl compounds, and the detection method is sensitive.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of perfluoro and polyfluoro alkyl compound detection, and particularly relates to a copper-based nano-carbon nitride material, a synthesis method and a method for electrochemically detecting perfluoro and polyfluoro alkyl compounds. BACKGROUND

[0002] Perfluoro and polyfluoro alkyl substances (PFAS) refer to organic compounds containing at least one perfluorocarbon atom. Due to the high bond energy of carbon fluoride (C-F) bond, PFAS has high temperature resistance, high stability and high persistence, and has wide industrial applications in aerospace, national defense, textile, construction, food, fire-fighting and medical products industries. The substances entering the environment cause widespread environmental pollution. PFAS can be detected all over the world. They also exist in drinking water, surface water, soil, wild animals, plants, atmosphere and human food sources. Moreover, PFAS pollution is persistent and not easily biodegradable, and is easy to accumulate in microorganisms, plants, animals and human bodies, thereby threatening the health of organisms, such as causing diseases in human body including prostate and kidney cancer, thyroid disease and diabetes, etc.

[0003] Perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS) and their salts are the most typical and most concerned PFAS, because they have been manufactured and used for the longest time, they are internationally recognized as "permanent chemicals", and are listed in the list of persistent organic pollutants. Various countries strengthen the control, limit or prohibit the use thereof, and formulate corresponding limits in drinking water standards. Water is an important carrier for the migration of pollutants, and water is also the main source of direct contact and intake of various pollutants by human body, and the current standard mainly limits the content of PFAS in water, so the detection of PFAS concentration in water is crucial. The existing method mainly relies on liquid chromatography and mass spectrometry (LC-MS / MS) equipment for detection, which needs complicated solid phase extraction for sample pretreatment, the instrument cost is high and trained personnel are needed for operation, so the detection cost of each sample is high. Therefore, it is necessary to develop a simple, rapid and sensitive method for detecting PFAS in water.

[0004] Electrochemical detection method is simple to operate, cheap and portable, has high sensitivity, and is widely concerned, and has been applied to the detection of organic pollutants such as antibiotics and bisphenol A. The electrochemical detection method is gradually rising for the detection of PFOA and PFOS. A typical strategy for sensitive detection of chemicals is to use high specific surface area materials, in which case, if the electrochemical detection method is used to sensitively detect PFAS in water, how to obtain high specific surface area, high adsorption and stable and sensitive electrode material is the key to solve the problem. SUMMARY

[0005] One of the technical problems to be solved by the present application is to provide a copper-based nanocarbon nitride material with high specific surface area, super-porous structure and high adsorption property and a synthesis method thereof.

[0006] To solve the above technical problems, the technical solution of the present application is: a synthesis method of a copper-based nanocarbon nitride material, comprising the following steps:

[0007] S11, calcining dicyandiamide in static air to synthesize a carbon nitride material;

[0008] S12, annealing the obtained carbon nitride material to 500-550℃; after repeated annealing for more than 3 times, a carbon nitride nanosheet is obtained;

[0009] S13, adding anhydrous copper chloride and the carbon nitride nanosheet in a mass ratio of 1:1-3 to a formamide solution, uniformly ultrasonic dispersing, controlling the reaction temperature to 110-125℃, reacting for 5-14h, and obtaining a powder material through centrifugation, washing and drying;

[0010] S14, heating the obtained powder material to 500-550℃ under an argon gas flow and keeping for 4-6h to prepare a copper-based nanocarbon nitride material.

[0011] Preferably, in step S11, the dicyandiamide is calcined in static air for 2-3h after heating to 500-600℃ at a heating rate of 2-5℃ / min in a tube furnace to synthesize the carbon nitride material.

[0012] Preferably, in step S12, the heating rate is controlled to 2-5℃ / min.

[0013] Preferably, in step S12, the annealing time is controlled to 5-8h each time.

[0014] Preferably, in step S12, the repeated annealing is performed for 4-6 times.

[0015] Preferably, in step S14, the heating rate is controlled to 2-5℃ / min.

[0016] Another technical problem to be solved by the present application is to apply the copper-based nanocarbon nitride material as described above to electrochemical detection of perfluoro and polyfluoro alkyl compounds.

[0017] A method for electrochemical detection of perfluoro and polyfluoro alkyl compounds by using the copper-based nanocarbon nitride material as described above, comprising the following steps:

[0018] S21, respectively configuring standard solutions containing perfluoro and polyfluoro alkyl compounds with different concentrations;

[0019] S22. Prepare a copper-based nano carbon nitride material solution with a concentration of 4–10 mg / mL, and uniformly coat the copper-based nano carbon nitride material solution onto the electrode surface to prepare the working electrode.

[0020] S23. Using a three-electrode system and an electrochemical workstation, the voltammetric characteristic curves (such as cyclic voltammetric curves or square wave voltammetric curves) of standard solutions of perfluorinated and polyfluoroalkyl compounds with different concentrations were measured. The peak currents of the voltammetric characteristic curves obtained by measuring standard solutions of perfluorinated and polyfluoroalkyl compounds with different concentrations were different.

[0021] S24. The Langmiur-Freundlich model is used to fit the data of peak current variation with the concentration of perfluorinated and polyfluoroalkyl compounds, thereby achieving accurate detection of the concentration of perfluorinated and polyfluoroalkyl compounds based on the peak current variation.

[0022] Preferably, in step S21, the standard solution comprises the following components: 4–6 mmol / L potassium ferricyanide, 4–6 mmol / L potassium ferrocyanide, 0.1–0.2 mol / L potassium bicarbonate, and 0.05–20 μg / L perfluorinated and polyfluoroalkyl compounds.

[0023] Compared with the prior art, the present invention has at least the following beneficial effects:

[0024] (1) The present invention prepares carbon nitride nanosheets by calcination and multiple annealing. The process is simple and does not require additional reagents and solutions. The carbon nitride material obtained by multiple annealing is a multi-layered nanoscale sheet with superior performance, which lays the foundation for the crystalline porous structure of subsequent copper ion exchange loading.

[0025] (2) This invention utilizes the reaction of anhydrous copper chloride and carbon nitride nanosheets in a formamide dispersion system at a certain temperature to react Cu 2+ By uniformly loading Cu onto the surface of carbon nitride nanosheets via ion exchange, the resulting copper-based carbon nitride nanomaterials have a high Cu loading capacity and more defined Cu atom active sites, giving them excellent high specific surface area, high adsorption capacity, and stable and sensitive chemical capture ability.

[0026] (3) This invention utilizes anhydrous copper chloride and carbon nitride nanosheets in a formamide dispersion system to prepare copper-based carbon nitride nanomaterials. No high-pressure equipment is required, the preparation process is safe, and the synthesis yield is high.

[0027] (4) The copper-based nano carbon nitride material obtained by this invention has a high Cu loading, more and more defined Cu atom active sites, and good high specific surface area, high adsorption and stable and sensitive chemical capture ability. The material is innovatively applied to the field of electrochemical detection. The detection method of this invention can accurately detect perfluorinated and polyfluoroalkyl compounds with a concentration of 0.05 to 20 μg / L based on the peak current change. The detection method is sensitive, simple to operate, and suitable for widespread application. Attached Figure Description

[0028] The following figures are intended only to illustrate and explain the present invention and do not limit the scope of the invention. Wherein:

[0029] Figure 1 This is a SEM image of the copper-based carbon nitride nanomaterial prepared in Example 1 of this invention at a size of 500 nm.

[0030] Figure 2 This is a SEM image of the copper-based carbon nitride nanomaterial prepared in Example 1 of this invention at a size of 5 μm;

[0031] Figure 3 This is a TEM image of the copper-based carbon nitride nanomaterial prepared in Example 1 of this invention at a size of 100 nm.

[0032] Figure 4 This is a TEM image of the copper-based carbon nitride nanomaterial prepared in Example 1 of this invention at a size of 5 nm.

[0033] Figure 5 This describes the C element distribution on the surface of the copper-based nano carbon nitride material prepared in Example 1 of this invention;

[0034] Figure 6 This describes the Cu element distribution on the surface of the copper-based nano carbon nitride material prepared in Example 1 of this invention.

[0035] Figure 7 This describes the nitrogen element distribution on the surface of the copper-based nano-carbon nitride material prepared in Example 1 of this invention.

[0036] Figure 8 This describes the distribution of O elements on the surface of the copper-based nano-carbon nitride material prepared in Example 1 of this invention.

[0037] Figure 9 These are the XRD patterns of carbon nitride nanosheets and copper-based carbon nitride nanomaterials obtained in Example 1 of this invention;

[0038] Figure 10 This is the surface XPS pattern of the copper-based nano-carbon nitride material prepared in Example 1 of this invention;

[0039] Figure 11 This is the CV curve obtained by cyclic voltammetry measurement in Embodiment 4 of the present invention;

[0040] Figure 12 This is the curve used in Embodiment 4 of the present invention to fit the data of peak current change with PFOA concentration using the Langmiur-Freundlich model;

[0041] Figure 13 This is the SWV curve obtained by square wave voltammetry in Embodiment 5 of the present invention;

[0042] Figure 14 This is the curve obtained by fitting the peak current to the PFOA concentration using the Langmiur-Freundlich model in Embodiment 5 of the present invention. Detailed Implementation

[0043] The present invention will be further illustrated below with reference to embodiments. In the following detailed description, only certain exemplary embodiments of the invention are described by way of illustration. Undoubtedly, those skilled in the art will recognize that various modifications can be made to the described embodiments without departing from the spirit and scope of the invention. Therefore, the descriptions in the embodiments are illustrative in nature and not intended to limit the scope of the claims.

[0044] Example 1

[0045] The synthesis method of copper-based carbon nitride nanomaterials includes the following steps:

[0046] S11. After heating to 550°C in a tube furnace at a heating rate of 2°C / min, dicyandiamide is calcined in static air for 2 hours to synthesize carbon nitride material.

[0047] S12. The obtained carbon nitride material is heated to 500℃ in a tube furnace at a heating rate of 5℃ / min for 5 hours and then annealed. After 5 repeated annealing cycles, carbon nitride nanosheets are obtained.

[0048] S13. Add 0.2g of anhydrous copper chloride and 0.35g of carbon nitride nanosheets to 100ml of formamide solution. The solution is blue. After sonication for 30min to disperse it evenly, stir in an oil bath at 120℃ for 12h. The solution becomes transparent. Then centrifuge and wash three times with ethanol. Finally, dry the powder in an oven at 80℃ for 8h to obtain the powder material.

[0049] S14. After grinding the obtained powder material, heat it to 500℃ under an argon gas flow and hold for 5 hours to obtain 0.38g of copper-based nano carbon nitride material.

[0050] ICP testing revealed that the copper-based nano-carbon nitride material contained 22.38% Cu, with a Cu utilization rate as high as 90%.

[0051] Example 2

[0052] The synthesis method of copper-based carbon nitride nanomaterials includes the following steps:

[0053] S11. After heating to 500°C in a tube furnace at a heating rate of 3°C / min, dicyandiamide is calcined in static air for 2 hours to synthesize carbon nitride material.

[0054] S12. The obtained carbon nitride material is heated to 500℃ in a tube furnace at a heating rate of 5℃ / min for 6 hours and then annealed. After four repeated annealing cycles, carbon nitride nanosheets are obtained.

[0055] S13. Add 0.2g of anhydrous copper chloride and 0.35g of carbon nitride nanosheets to 100ml of formamide solution. The solution is blue. After sonication for 30min to disperse it evenly, stir in an oil bath at 115℃ for 13h. The solution becomes transparent. Then centrifuge and wash three times with ethanol. Finally, dry the powder in an oven at 80℃ for 8h to obtain the powder material.

[0056] S14. After grinding the obtained powder material, heat it to 550°C under an argon gas flow and hold for 5 hours to obtain 0.36g of copper-based nano carbon nitride material.

[0057] ICP analysis revealed that the copper-based nano-carbon nitride material contained 21.76% Cu, with a Cu utilization rate of approximately 83%.

[0058] Example 3

[0059] The synthesis method of copper-based carbon nitride nanomaterials includes the following steps:

[0060] S11. After heating to 550°C in a tube furnace at a heating rate of 2°C / min, dicyandiamide is calcined in static air for 2 hours to synthesize carbon nitride material.

[0061] S12. The obtained carbon nitride material is heated to 500℃ in a tube furnace at a heating rate of 5℃ / min for 5 hours and then annealed. After 6 repeated annealing cycles, carbon nitride nanosheets are obtained.

[0062] S13. Add 0.2g of anhydrous copper chloride and 0.35g of carbon nitride nanosheets to 100ml of formamide solution. The solution is blue. After sonication for 30min to disperse it evenly, stir in an oil bath at 125℃ for 12h. The solution becomes transparent. Then centrifuge and wash three times with ethanol. Finally, dry the powder in an oven at 80℃ for 8h to obtain the powder material.

[0063] S14. After grinding the obtained powder material, heat it to 550°C under an argon gas flow and hold for 5 hours to obtain 0.37g of copper-based nano carbon nitride material.

[0064] ICP testing revealed that the copper-based nano-carbon nitride material contained 22.05% Cu, with a Cu utilization rate of approximately 87%.

[0065] Example 4

[0066] The copper-based carbon nitride nanomaterials prepared in Example 1 were applied to the electrochemical detection of perfluorinated and polyfluoroalkyl compounds. The application method included the following steps:

[0067] S21. Prepare 20 ml of standard solutions containing different concentrations (0.05-20 μg / L) of PFOA. The standard solutions contain 5 mmol / L potassium ferricyanide, 5 mmol / L potassium ferrocyanide, and 0.1 mol / L potassium bicarbonate.

[0068] S22. Weigh 5 mg of the synthesized copper-based carbon nitride nanomaterial and add it to a centrifuge tube containing 950 μL of ethanol and 50 μL of Nafion solution. Sonicate in ice water for 30 min to uniformly disperse the material in the solution, obtaining a 5 mg / mL copper-based carbon nitride nanomaterial solution. Apply the electrode material using a multiple small-batch application method, specifically by applying 10 μL of the material solution to a 1 cm layer each time. 2 ×1cm 2 The glassy carbon electrode surface is uniformly coated and then placed in an oven to dry. After the surface is dry, it is taken out and the above coating steps are repeated 5 times to prepare a working electrode with uniform material coating that is not easy to fall off.

[0069] S23. A three-electrode system was used, with a glassy carbon electrode coated with the material as the working electrode, an Ag / AgCl electrode as the reference electrode, and a platinum sheet electrode as the counter electrode. The three electrodes were fixed and inserted into the standard solution containing potassium ferrocyanide and potassium ferrocyanide. Cyclic voltammetry (CV) curves were measured using an electrochemical workstation: the initial potential was 0.6V, the second peak potential was -0.2V, the final potential was 0.6V, and the scan rate was 0.01V / s. The peak current of the oxidation peak in the CV curves obtained for different concentrations of PFOA varied (see reference). Figure 11 );

[0070] S24. The Langmiur-Freundlich model was used to fit the data on peak current variation with PFOA concentration (reference). Figure 12 This allows for rapid and accurate detection of PFOA concentration based on changes in peak current.

[0071] Example 5

[0072] The copper-based carbon nitride nanomaterials prepared in Example 2 were applied to the electrochemical detection of perfluorinated and polyfluoroalkyl compounds. The application method included the following steps:

[0073] S21. Prepare 20 ml of standard solutions containing different concentrations (0.05-20 μg / L) of PFOA. The standard solutions contain 5 mmol / L potassium ferricyanide, 5 mmol / L potassium ferrocyanide, and 0.1 mol / L potassium bicarbonate.

[0074] S22. Weigh 5 mg of the synthesized copper-based carbon nitride nanomaterial and add it to a centrifuge tube containing 950 μL of ethanol and 50 μL of Nafion solution. Sonicate in ice water for 30 min to uniformly disperse the material in the solution, obtaining a 5 mg / mL copper-based carbon nitride nanomaterial solution. Apply the electrode material using a multiple small-batch application method, specifically by applying 10 μL of the material solution to a 1 cm layer each time. 2 ×1cm 2 The glassy carbon electrode surface is uniformly coated and then placed in an oven to dry. After the surface is dry, it is taken out and the above coating steps are repeated 5 times to prepare a working electrode with uniform material coating that is not easy to fall off.

[0075] S23. A three-electrode system was used, with a glassy carbon electrode coated with the material as the working electrode, an Ag / AgCl electrode as the reference electrode, and a platinum sheet electrode as the counter electrode. The three electrodes were fixed and inserted into the standard solution containing potassium ferrocyanide and potassium ferrocyanide. Square wave voltammetry (SWV) curves were measured using an electrochemical workstation: initial potential -0.2V, final potential 0.6V, pulse height 10mV, step height 5mV, frequency 2Hz. The peak current of the SWV curves obtained with different concentrations of PFOA varied (see reference). Figure 13 );

[0076] S24. The Langmiur-Freundlich model was used to fit the data on peak current variation with PFOA concentration (reference). Figure 14 This allows for rapid and accurate detection of PFOA concentration based on changes in peak current.

[0077] Comparative Example 1

[0078] The difference between Comparative Example 1 and Example 1 is that in step S12, the carbon nitride material is annealed once. The specific details are as follows:

[0079] S11. After heating to 550°C in a tube furnace at a heating rate of 2°C / min, dicyandiamide is calcined in static air for 2 hours to synthesize carbon nitride material.

[0080] S12. The obtained carbon nitride material is annealed in a tube furnace at a heating rate of 5℃ / min to 500℃ for 5 hours to obtain crystalline carbon nitride material.

[0081] S13. Add 0.2g of anhydrous copper chloride and 0.35g of carbon nitride crystalline material to 100ml of formamide solution. The solution is blue. After sonication for 30min to disperse it evenly, stir in an oil bath at 120℃ for 12h. The solution color does not change significantly. Then centrifuge and wash three times with ethanol. Finally, dry the powder in an oven at 80℃ for 8h to obtain the powder material.

[0082] S14. The obtained powder material was ground and heated to 500°C under an argon gas flow and held for 5 hours to obtain 0.352g of comparative target material 1.

[0083] ICP testing showed that the Cu content in target material 1 was 2.18%, and the Cu utilization rate was approximately 8%.

[0084] Comparative Example 2

[0085] The difference between Comparative Example 2 and Example 1 is that the temperature of the oil bath is different in step S13. The specific details are as follows:

[0086] S11. After heating to 550°C in a tube furnace at a heating rate of 2°C / min, dicyandiamide is calcined in static air for 2 hours to synthesize carbon nitride material.

[0087] S12. The obtained carbon nitride material is heated to 500℃ in a tube furnace at a heating rate of 5℃ / min for 5 hours and then annealed. After 5 repeated annealing cycles, carbon nitride nanosheets are obtained.

[0088] S13. Add 0.2g of anhydrous copper chloride and 0.35g of carbon nitride nanosheets to 100ml of formamide solution. The solution is blue. After sonication for 30min to disperse it evenly, stir in an oil bath at 100℃ for 12h. The solution color does not change significantly. Then centrifuge and wash three times with ethanol. Finally, dry the powder in an oven at 80℃ for 8h to obtain the powder material.

[0089] S14. The obtained powder material was ground and heated to 500°C under an argon gas flow and held for 5 hours to obtain 0.356g of comparative target material 2.

[0090] ICP testing showed that the Cu content in target material 2 was 3.25%, and the Cu utilization rate was approximately 12%.

[0091] Comparative Example 3

[0092] The difference between Comparative Example 3 and Example 1 is that the temperature of the oil bath is different in step S13. The specific details are as follows:

[0093] S11. After heating to 550°C in a tube furnace at a heating rate of 2°C / min, dicyandiamide is calcined in static air for 2 hours to synthesize carbon nitride material.

[0094] S12. The obtained carbon nitride material is heated to 500℃ in a tube furnace at a heating rate of 5℃ / min for 5 hours and then annealed. After 5 repeated annealing cycles, carbon nitride nanosheets are obtained.

[0095] S13. 0.2g of anhydrous copper chloride and 0.35g of carbon nitride nanosheets were added to 100ml of formamide solution. The solution turned blue. After being sonicated for 30min to disperse it evenly, it was stirred in an oil bath at 80℃ for 12h. The solution color did not change, indicating that Cu could not be loaded onto carbon nitride nanosheets under this temperature condition.

[0096] Experimental Analysis:

[0097] Figure 1 and Figure 2 The images show SEM images of the copper-based carbon nitride nanomaterials prepared in Example 1 at 500 nm and 5 μm sizes. Figure 3 and Figure 4 These are TEM images of the copper-based carbon nitride nanomaterials prepared in Example 1 at 100 nm and 5 nm sizes. (The images were obtained through...) Figures 1 to 4 It can be seen that the copper-based nano-carbon nitride material prepared by the method of the present invention is a nanoscale material with good porosity on its surface.

[0098] Figures 5 to 8 This shows the surface elemental distribution of the copper-based carbon nitride nanomaterial prepared in Example 1. Figure 5 The distribution of C elements; Figure 6 The distribution of Cu element; Figure 7 The distribution of element N; Figure 8 This shows the distribution of element O. From... Figures 5 to 8 It can be seen that Cu is uniformly loaded on the surface of the copper-based nano carbon nitride material.

[0099] Figure 9 The black line represents the XRD pattern of the carbon nitride nanosheets obtained in Example 1, and the red line represents the XRD pattern of the copper-based carbon nitride nanomaterials prepared in Example 1. Analysis of the spectra shows that they have the same diffraction peaks, indicating the successful synthesis of the copper-based carbon nitride nanomaterials. Furthermore, the copper loading did not alter the crystal structure of the substrate carbon nitride nanosheets, and there were no related diffraction peaks for the copper phase, indicating that the copper was uniformly distributed on the substrate and did not aggregate to form copper crystals.

[0100] Figure 10This is the surface XPS spectrum of the copper-based carbon nitride nanomaterial prepared in Example 1. Analysis of the spectrum demonstrates the successful synthesis of the copper-based carbon nitride nanomaterial and the successful loading of copper.

[0101] By comparing Example 1 and Comparative Example 1, it can be seen that the carbon nitride material obtained by multiple annealing is a multi-layered nanoscale sheet. Compared with single annealing, it can have better performance and can lay the foundation for the crystalline porous structure for subsequent copper ion exchange loading, thereby increasing the copper loading.

[0102] By comparing Example 1 with Comparative Examples 2 and 3, it can be shown that under the same system conditions, at a lower reaction temperature, Cu... 2+ It is impossible to uniformly load copper-based carbon nitride nanosheets onto the surface via ion exchange, thus preventing the acquisition of copper-based carbon nitride nanomaterials with more defined Cu atom active sites and making them unsuitable for electrochemical detection of perfluorinated and polyfluoroalkyl compounds.

[0103] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method for synthesizing copper-based nano-carbon nitride materials, characterized in that, Includes the following steps: S11. Dicyandiamide is calcined in static air to synthesize carbon nitride materials; S12. The obtained carbon nitride material is heated to 500-550℃ for annealing; after more than 3 repeated annealings, carbon nitride nanosheets are obtained. S13. Anhydrous copper chloride and carbon nitride nanosheets are added to formamide solution at a mass ratio of 1:1 to 3. After being ultrasonically dispersed evenly, the reaction temperature is controlled at 110 to 125°C and the reaction is carried out for 5 to 14 hours. The powder material is obtained by centrifugation, washing and drying. S14. The obtained powder material is heated to 500-550℃ under an argon gas flow and held for 4-6 hours to obtain copper-based nano carbon nitride material.

2. The method for synthesizing copper-based nano-carbon nitride materials as described in claim 1, characterized in that: In step S11, after heating to 500-600°C in a tube furnace at a heating rate of 2-5°C / min, dicyandiamide is calcined in static air for 2-3 hours to synthesize carbon nitride material.

3. The method for synthesizing copper-based nano-carbon nitride materials as described in claim 1, characterized in that: In step S12, the heating rate is controlled at 2-5℃ / min.

4. The method for synthesizing copper-based nano-carbon nitride materials as described in claim 1, characterized in that: In step S12, the annealing time for each annealing is controlled between 5 and 8 hours.

5. The method for synthesizing copper-based nano-carbon nitride materials as described in claim 1, characterized in that: In step S12, the annealing process is repeated 4 to 6 times.

6. The method for synthesizing copper-based nano-carbon nitride materials as described in claim 1, characterized in that: In step S14, the heating rate is controlled at 2-5℃ / min.

7. Copper-based nano-carbon nitride material prepared by the synthesis method according to any one of claims 1 to 6.

8. The application of the copper-based nanocarbon nitride material according to claim 7 in the electrochemical detection of perfluorinated and polyfluoroalkyl compounds.

9. A method for electrochemical detection of perfluorinated and polyfluoroalkyl compounds using the copper-based nano-carbon nitride material according to claim 7, characterized in that, Includes the following steps: S21. Prepare standard solutions containing different concentrations of perfluorinated and polyfluoroalkyl compounds respectively; S22. Prepare a copper-based nano carbon nitride material solution with a concentration of 4–10 mg / mL, and uniformly coat the copper-based nano carbon nitride material solution onto the electrode surface to prepare the working electrode. S23. Using a three-electrode system and an electrochemical workstation, the voltammetric characteristic curves of standard solutions of perfluorinated and polyfluoroalkyl compounds with different concentrations were measured. The peak currents of the voltammetric characteristic curves of standard solutions of perfluorinated and polyfluoroalkyl compounds with different concentrations were different. S24. The Langmiur-Freundlich model is used to fit the data of peak current variation with the concentration of perfluorinated and polyfluoroalkyl compounds, thereby achieving accurate detection of the concentration of perfluorinated and polyfluoroalkyl compounds based on the peak current variation.

10. The detection method as described in claim 9, characterized in that: In step S21, the standard solution comprises the following components: 4–6 mmol / L potassium ferricyanide, 4–6 mmol / L potassium ferrocyanide, 0.1–0.2 mol / L potassium bicarbonate, and 0.05–20 μg / L perfluorinated and polyfluoroalkyl compounds.

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