Micro-nano electrochemical sensor for in-situ detection of nitrite and detection system
By constructing a WO3/WO3-x nanoarray on the surface of carbon cloth and loading it with a nitrite ion carrier, the problems of hydrophobicity and weak electrochemical activity of carbon cloth electrodes were solved, and high-sensitivity and rapid nitrite detection was achieved.
Patent Information
- Application Number
- CN202423054973.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-12-11
- Publication Date
- 2025-11-25
- Estimated Expiration
- 2034-12-11
AI Technical Summary
Existing carbon cloth as an electrode substrate material for electrochemical sensors suffers from problems such as strong hydrophobicity, low specific surface area, and weak electrochemical activity, which limits its application in nitrite detection.
A WO3/WO3-x nanoarray was constructed on the surface of carbon cloth and loaded with nitrite ion carriers. Electrodes were prepared by hydrothermal and alcoholic reactions to improve the electrochemical active area and electron transfer rate.
The electrochemical activity of the electrode was enhanced, improving the sensitivity and anti-interference ability of nitrite detection, thus enabling rapid nitrite detection with a low detection limit.
Smart Images
Figure CN223597585U_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The utility model relates to a kind of micro-nano electrochemical sensors and detection systems for in-situ detection of nitrite, belong to electrochemical sensor technical field. BACKGROUND
[0002] Nitrite widely exists in nature, and is also commonly used in industry and food processing. However, excessive nitrite can form carcinogen-nitrosamine, which may cause serious health problems, and nitrite can also harm the living environment of human beings. Therefore, it is of great significance to strictly monitor and control the generation and emission of nitrite for protecting human health and environment.
[0003] Currently, methods commonly used for detecting nitrite include spectrophotometry, high-performance liquid chromatography, capillary electrophoresis and electrochemical detection. Electrochemical detection has attracted widespread attention due to its fast response, high sensitivity, high selectivity, simple operation and preparation diversity. Carbon cloth, as a substrate material for electrodes of electrochemical detection sensors, has the advantages of low cost, good thermal and chemical stability, low thermal expansion coefficient and easy availability of raw materials. However, the strong hydrophobicity, low specific surface area and weak electrochemical activity of commercial carbon cloth limit its application in electrochemical sensing. SUMMARY
[0004] The utility model aims at the deficiencies in the prior art and provides a kind of micro-nano electrochemical sensors and detection systems for in-situ detection of nitrite, which solves the problems of electrode substrate material carbon cloth in sensors and improves the effect of electrochemical sensors for detecting nitrite in water.
[0005] To achieve the above object, the utility model adopts the following technical scheme:
[0006] A kind of micro-nano electrochemical sensors for in-situ detection of nitrite, which is provided with reference electrode, counter electrode and working electrode;The reference electrode is connected with working electrode by voltage measuring instrument, for measuring the potential of working electrode relative to reference electrode;The counter electrode is used to connect the anode of polarization power supply;The working electrode is used to connect the cathode of polarization power supply, and the working electrode includes carbon substrate, WO3 / WO 3-x Nano array layer is provided on the surface of the carbon substrate, and nitrite ion carrier is loaded on the WO3 / WO 3-x Nano array layer.
[0007] Further, the reference electrode is saturated calomel electrode, and the counter electrode is platinum sheet electrode.
[0008] Further, the carbon substrate is carbon cloth.
[0009] Further, the molecular formula of the nitrite ion carrier is C 36 H 46 N2CoO2 and its chemical structure is:
[0010] .
[0011] The preparation method of the working electrode comprises the following steps:
[0012] S1, hydrophilic treatment of carbon cloth: the carbon cloth (CC) is sequentially ultrasonically cleaned in acetone, ethanol and deionized water for 10 min, then the carbon cloth is dried, then the carbon cloth is immersed in a mixed acid solution for 12 h, then taken out, then washed with deionized water and dried for standby use; the mixed acid solution is obtained by mixing concentrated sulfuric acid and concentrated nitric acid; the frequency of the ultrasonic used in the ultrasonic cleaning is 25 KHz; the mixed acid solution is obtained by mixing concentrated sulfuric acid and concentrated nitric acid, and the volume ratio of concentrated sulfuric acid and concentrated nitric acid is 3:1. After the carbon cloth is treated by ultrasonic in acetone, ethanol and deionized water to remove impurities on the surface of the carbon cloth, the carbon cloth is placed in the mixed acid solution prepared by mixing concentrated sulfuric acid and concentrated nitric acid in proportion for treatment, and the carbon cloth is subjected to hydrophilic modification treatment, which is helpful for subsequent loading of tungsten oxide;
[0013] S2, synthesis of electrode WO3 / WO 3-x CC: take sodium tungstate dihydrate and potassium oxalate monohydrate and dissolve them in distilled water, and then adjust the pH to 1.4-1.6 with dilute hydrochloric acid and stir for 2 h to obtain a precursor aqueous solution; take tungsten hexachloride and dissolve it in ethanol to obtain a tungsten hexachloride ethanol solution; take the carbon cloth treated in step S1 and place it in a reaction kettle, then pour the precursor aqueous solution into the reaction kettle, then seal the reaction kettle at 170-190℃ for 11-13 h, then take out the carbon cloth and rinse it with ethanol and deionized water in sequence, then dry it at 55-60℃, then place it in an annealing furnace at 540-560℃ for 2 h, then cool it to room temperature, then place the carbon cloth in the tungsten hexachloride ethanol solution, then react at 170-190℃ for 11-13 h, then take out the carbon cloth and rinse it with ethanol and deionized water in sequence, then dry it at room temperature to obtain the electrode WO3 / WO 3-x CC; 0.03-0.05 mol of sodium tungstate dihydrate and 0.017-0.019 mol of potassium oxalate monohydrate are contained in 1 L of the precursor aqueous solution; 0.03-0.05 mol of tungsten hexachloride is contained in 1 L of the tungsten hexachloride ethanol solution;
[0014] S3, preparation of nitrite ion carrier: take o-phenylenediamine and 3,5-di-tert-butyl salicylaldehyde to be dissolved in methanol to obtain reaction liquid A, 0.15-0.17 mol of o-phenylenediamine and 0.31-0.33 mol of 3,5-di-tert-butyl salicylaldehyde are contained in each 1L of reaction liquid A, then add formic acid to reaction liquid A after mixing and stir at 70-90 DEG C for 12-13h, the volume ratio of reaction liquid A and formic acid is (4000-6000):(4-6); in step S42, the molar ratio of intermediate I and cobalt acetate tetrahydrate is 1:1, then filter residue I under reduced pressure to obtain, wash residue I with ethanol and dry to obtain intermediate I; take the obtained intermediate I to be dissolved in chloroform to obtain reaction liquid B, 0.06-0.08 mol of intermediate I is contained in each 1L of reaction liquid B; take cobalt acetate tetrahydrate to be dissolved in ethanol to obtain reaction liquid C, 0.12-0.16 mol of cobalt acetate tetrahydrate is contained in each 1L of reaction liquid C; slowly drop reaction liquid C into reaction liquid B, stir at room temperature for 2-3h after dropping is completed, then filter under reduced pressure to obtain residue II, wash residue II with ethanol and dry to obtain nitrite ion carrier.
[0015] S4, preparation of electrode WO3 / WO 3-x -3NN-CC: take nitrite ion carrier to be dissolved in N,N-dimethylformamide (DMF), then add equal volume of Nafion solution to uniformly mix to obtain mixed liquid, drop the mixed liquid on electrode WO3 / WO 3-x -CC obtained in step S2, then dry at room temperature for 24h, then repeat dropping the mixed liquid on electrode WO3 / WO 3-x -CC 2 times, place at room temperature for 24h after each dropping is completed to obtain electrode WO3 / WO 3-x -3NN-CC, namely the working electrode.
[0016] A micro-nano electrochemical detection system for in-situ detection of nitrite, comprising the novel micro-nano electrochemical sensor for in-situ detection of nitrite, a polarization power supply, an ammeter, a voltmeter and a supporting electrolyte, the supporting electrolyte is phosphate buffer solution (PBS) with a concentration of 0.1M and pH=6.5; the counter electrode of the electrochemical sensor is electrically connected with the ammeter, and the ammeter is electrically connected with the positive electrode of the polarization power supply; the reference electrode of the electrochemical sensor is electrically connected with the voltmeter; the working electrode of the electrochemical sensor is electrically connected with the voltmeter and the negative electrode of the polarization power supply respectively; when the electrochemical detection system works, the reference electrode, the counter electrode and the working electrode are placed in the same supporting electrolyte.
[0017] A micro-nano electrochemical detection system for detecting nitrite in situ, comprising the novel micro-nano electrochemical sensor for detecting nitrite in situ, an electrochemical workstation and a supporting electrolyte, wherein the supporting electrolyte is a phosphate buffer solution (PBS) with a concentration of 0.1 M and a pH of 6.5; the counter electrode, the reference electrode and the working electrode of the electrochemical sensor are electrically connected to the electrochemical workstation; and the reference electrode, the counter electrode and the working electrode are placed in the same supporting electrolyte when the electrochemical detection system is in operation.
[0018] Compared with the prior art, the technical scheme has the following beneficial effects:
[0019] Through hydrothermal reaction, alcohol thermal reaction and annealing step-by-step, WO3 / WO 3-x nanometer arrays composed of micro-nano particles are constructed on the surface of carbon cloth, and a unique nitrite ion carrier is loaded on the carbon cloth through Nafion solution, so as to finally prepare an electrode for detecting nitrite ions, which has a larger electrochemical active area, a faster electron transfer rate and a significant catalytic effect on the oxidation reaction of nitrite ions on the electrode surface. The electrode is used as a working electrode together with a reference electrode and a counter electrode to form a novel micro-nano electrochemical sensor for detecting nitrite in situ, and appropriate polarization power, ammeter and voltmeter and other instruments are configured, so as to finally obtain an electrochemical detection system for detecting nitrite, which can be used for detecting nitrite ions in water and has the advantages of convenient operation, fast detection speed, low detection limit, high sensitivity and strong anti-interference ability. BRIEF DESCRIPTION OF DRAWINGS
[0020] Figure 1 is a synthetic route diagram of the nitrite ion carrier described in Example 1.
[0021] Figure 2 is a scanning electron microscope image of the carbon cloth without loading tungsten oxide described in Example 1.
[0022] Figure 3 is a scanning electron microscope image of the carbon cloth after loading WO3 / WO 3-x described in Example 1.
[0023] Figure 4 is an X-ray energy spectrum element distribution map of the carbon cloth after loading WO3 / WO 3-x described in Example 1, wherein A is a corresponding scanning electron microscope image, C is a carbon element image, W is a tungsten element image, and O is an oxygen element image.
[0024] Figure 5 is a relationship diagram between the concentration of sodium nitrite (µM level) detected in Example 4 and the current response value.
[0025] Figure 6is a linear relationship diagram between the concentration of sodium nitrite (in the order of micromole) detected in Example 4 and the current response value.
[0026] Figure 7 is a relationship diagram between the concentration of sodium nitrite (in the order of millimole) detected in Example 4 and the current response value.
[0027] Figure 8 is a linear relationship diagram between the concentration of sodium nitrite (in the order of millimole) detected in Example 4 and the current response value.
[0028] Figure 9 is a data diagram of the results of detecting different ion solutions in Example 4.
[0029] Figure 10 is a connection diagram of the electrochemical detection system for detecting nitrite described in Example 4.
[0030] Reference numerals: 1-polarized power supply, 2-current meter, 3-voltage meter, 4-supporting electrolyte, 5-reference electrode, 6-counter electrode, 7-working electrode. DETAILED DESCRIPTION
[0031] The utility model will be further described below in combination with the drawings and examples, but the utility model is not limited to the examples. The specific experimental conditions and methods not specified in the following examples are usually conventional means familiar to those skilled in the art.
[0032] Example 1: A micro-nano electrochemical sensor for in-situ detection of nitrite, which is provided with a reference electrode, a counter electrode and a working electrode; the reference electrode is connected with the working electrode through a voltage measuring instrument, for measuring the potential of the working electrode relative to the reference electrode; the counter electrode is used for connecting the positive electrode of the polarization power supply; the working electrode is used for connecting the negative electrode of the polarization power supply, and the working electrode comprises a carbon substrate, a WO3 / WO 3-x nanometer array layer is arranged on the surface of the carbon substrate, and the WO3 / WO 3-x nanometer array layer is loaded with a nitrite ion carrier; the reference electrode is a saturated calomel electrode; the counter electrode is a platinum sheet electrode; the carbon substrate is carbon cloth; the molecular formula of the nitrite ion carrier is C 36 H 46 N2CoO2, and its chemical structural formula is:
[0033] .
[0034] The preparation method of the working electrode comprises the following steps:
[0035] S1, hydrophilic treatment of carbon cloth: the carbon cloth (CC) is sequentially ultrasonically cleaned in acetone, ethanol and deionized water for 10 min, then the carbon cloth is dried, then the carbon cloth is immersed in a mixed acid solution for 12 h, then taken out, then washed with deionized water and dried; the mixed acid solution is obtained by mixing concentrated sulfuric acid and concentrated nitric acid; the frequency of the ultrasonic used in the ultrasonic cleaning is 25 KHz; the mixed acid solution is obtained by mixing concentrated sulfuric acid and concentrated nitric acid and the volume ratio of concentrated sulfuric acid and concentrated nitric acid is 3:1. After the carbon cloth is treated by ultrasonic in acetone, ethanol and deionized water to remove impurities on the surface of the carbon cloth, the carbon cloth is placed in the mixed acid solution prepared by mixing concentrated sulfuric acid and concentrated nitric acid in a certain proportion for treatment, and the carbon cloth is subjected to hydrophilic modification treatment, which is helpful for subsequent loading of tungsten oxide;
[0036] S2, electrode WO3 / WO 3-x —CC: sodium tungstate dihydrate and potassium oxalate monohydrate are dissolved in distilled water, and after the pH is adjusted to 1.5 with 1M dilute hydrochloric acid, stirring is carried out for 2 h to obtain a precursor aqueous solution; tungsten hexachloride is dissolved in ethanol to obtain a tungsten hexachloride ethanol solution; the carbon cloth treated in step S1 is placed in a reaction kettle, then the precursor aqueous solution is poured into the reaction kettle, then the reaction kettle is sealed and reacted at 180℃ for 12 h, then the carbon cloth is taken out, washed with ethanol and deionized water in sequence, and then dried at 58℃, then placed in an annealing furnace at 550℃ for 2 h, cooled to room temperature, then placed in the tungsten hexachloride ethanol solution, then reacted at 180℃ for 12 h, then the carbon cloth is taken out, washed with ethanol and deionized water in sequence, and then dried at room temperature to obtain the electrode WO3 / WO 3-x —CC; 0.04 mol of sodium tungstate dihydrate and 0.018 mol of potassium oxalate monohydrate are contained in 1 L of the precursor aqueous solution; 0.04 mol of tungsten hexachloride is contained in 1 L of the tungsten hexachloride ethanol solution;
[0037] S3, preparation of nitrite ion carrier: o-phenylenediamine and 3,5-di-tert-butyl salicylaldehyde are dissolved in methanol to obtain reaction liquid A, 0.16 mol of o-phenylenediamine and 0.32 mol of 3,5-di-tert-butyl salicylaldehyde are contained in 1 L of the reaction liquid A, then formic acid is added to the reaction liquid A, mixed and stirred at 80℃ for 12 h, the volume ratio of the reaction liquid A and formic acid is 5000:5; the molar ratio of the intermediate I and cobalt acetate tetrahydrate is 1:1, then the filter residue I is obtained by reduced pressure filtration, the filter residue I is washed with ethanol and dried to obtain the intermediate I; the obtained intermediate I is dissolved in chloroform to obtain reaction liquid B, 0.07 mol of the intermediate I is contained in 1 L of the reaction liquid B; cobalt acetate tetrahydrate is dissolved in ethanol to obtain reaction liquid C, 0.14 mol of cobalt acetate tetrahydrate is contained in 1 L of the reaction liquid C; the reaction liquid C is slowly added to the reaction liquid B, stirred at room temperature for 2 h after the addition is completed, then filtered under reduced pressure to obtain filter residue II, which is washed with ethanol and dried to obtain the nitrite ion carrier.
[0038] S4, electrode WO3 / WO 3-x Preparation of —3NN—CC: nitrite ion carrier was dissolved in N,N-dimethylformamide (DMF), then an equal volume of Nafion solution was added to uniformly mix to obtain a mixed solution, the mixed solution was added dropwise to the electrode WO3 / WO 3-x —CC obtained in step S2, then dried at room temperature for 24 h, then the mixed solution was repeatedly added dropwise to the electrode WO3 / WO 3-x —CC for 2 times, and after each dropwise addition, it was placed at room temperature for drying for 24 h to obtain the electrode WO3 / WO 3-x —3NN—CC, that is, the working electrode.
[0039] Embodiment 2: A micro-nano electrochemical sensor for in-situ detection of nitrite, which is provided with a reference electrode, a counter electrode and a working electrode; the reference electrode is connected with the working electrode through a voltage measuring instrument, for measuring the potential of the working electrode relative to the reference electrode; the counter electrode is used for connecting the positive electrode of a polarization power supply; the working electrode is used for connecting the negative electrode of the polarization power supply, and the working electrode comprises a carbon substrate, the surface of the carbon substrate is provided with a WO3 / WO 3-x nanometer array layer, the WO3 / WO 3-x nanometer array layer is loaded with a nitrite ion carrier; the reference electrode is a saturated calomel electrode; the counter electrode is a platinum sheet electrode; the carbon substrate is carbon cloth; the molecular formula of the nitrite ion carrier is C 36 H 46 N2CoO2, and its chemical structural formula is:
[0040] .
[0041] The preparation method of the working electrode comprises the following steps:
[0042] S1, hydrophilic treatment of carbon cloth: carbon cloth (CC) is sequentially ultrasonically cleaned in acetone, ethanol and deionized water for 10 min, then the carbon cloth is dried, then the carbon cloth is immersed in a mixed acid solution for 12 h, taken out, then washed with deionized water and dried for standby use; the mixed acid solution is obtained by mixing concentrated sulfuric acid and concentrated nitric acid; the frequency of the ultrasonic wave used in the ultrasonic cleaning is 25 KHz; the mixed acid solution is obtained by mixing concentrated sulfuric acid and concentrated nitric acid, and the volume ratio of the concentrated sulfuric acid and the concentrated nitric acid is 3:1. After the carbon cloth is treated by ultrasonic treatment in acetone, ethanol and deionized water to remove impurities on the surface of the carbon cloth, the carbon cloth is placed in the mixed acid solution prepared by mixing concentrated sulfuric acid and concentrated nitric acid in a certain proportion for treatment, so as to perform hydrophilic modification treatment on the carbon cloth, which is helpful for subsequent loading of tungsten oxide;
[0043] S2, electrode WO3 / WO 3-x—CC: sodium tungstate dihydrate and potassium oxalate monohydrate were dissolved in distilled water, and the pH was adjusted to 1.4 with dilute hydrochloric acid with a concentration of 2M after stirring for 2h to obtain a precursor aqueous solution; tungsten hexachloride was dissolved in ethanol to obtain a tungsten hexachloride ethanol solution; the carbon cloth treated in step S1 was placed in a reaction kettle, then the precursor aqueous solution was poured into the reaction kettle, and the reaction kettle was sealed and reacted at 170°C for 13h, then the carbon cloth was taken out and washed with ethanol and deionized water in sequence, and then dried at 55°C, and then annealed at 540°C for 2h, and then cooled to room temperature, and then the carbon cloth was placed in the tungsten hexachloride ethanol solution, and then reacted at 170°C for 13h, then the carbon cloth was taken out and washed with ethanol and deionized water in sequence, and then dried at room temperature to obtain the electrode WO3 / WO 3-x —CC; 0.03mol of sodium tungstate dihydrate and 0.017mol of potassium oxalate monohydrate were contained in 1L of the precursor aqueous solution; 0.03mol of tungsten hexachloride was contained in 1L of the tungsten hexachloride ethanol solution;
[0044] S3, preparation of nitrite ion carrier: o-phenylenediamine and 3,5-di-tert-butyl salicylaldehyde were dissolved in methanol to obtain reaction liquid A, 0.15mol of o-phenylenediamine and 0.31mol of 3,5-di-tert-butyl salicylaldehyde were contained in 1L of the reaction liquid A, then formic acid was added to the reaction liquid A and stirred at 70°C for 13h, the volume ratio of the reaction liquid A to formic acid was 4000:6; the molar ratio of the intermediate I to cobalt acetate tetrahydrate was 1:1, then the filter residue I was obtained by vacuum filtration, the filter residue I was washed with ethanol and dried to obtain the intermediate I; the obtained intermediate I was dissolved in chloroform to obtain reaction liquid B, 0.06mol of the intermediate I was contained in 1L of the reaction liquid B; cobalt acetate tetrahydrate was dissolved in ethanol to obtain reaction liquid C, 0.12mol of cobalt acetate tetrahydrate was contained in 1L of the reaction liquid C; the reaction liquid C was slowly added to the reaction liquid B, and then stirred at room temperature for 2h after the addition was completed, then the filter residue II was obtained by vacuum filtration, and the filter residue II was washed with ethanol and dried to obtain the nitrite ion carrier.
[0045] S4, electrode WO3 / WO 3-x —3NN—CC: the nitrite ion carrier was dissolved in N,N-dimethylformamide (DMF), then an equal volume of Nafion solution was added and uniformly mixed to obtain a mixed liquid, the mixed liquid was added dropwise to the electrode WO3 / WO 3-x —CC obtained in step S2, and then dried at room temperature for 24h, then the mixed liquid was added dropwise to the electrode WO3 / WO 3-x —CC obtained in step S2 twice, and then dried at room temperature for 24h after each dropwise addition was completed to obtain the electrode WO3 / WO 3-x —3NN—CC, that is, the working electrode.
[0046] Embodiment 3: A micro-nano electrochemical sensor for in-situ detection of nitrite, which is provided with a reference electrode, a counter electrode and a working electrode; the reference electrode is connected with the working electrode through a voltage measuring instrument, for measuring the potential of the working electrode relative to the reference electrode; the counter electrode is used for connecting the positive pole of a polarization power supply; the working electrode is used for connecting the negative pole of the polarization power supply, and the working electrode comprises a carbon substrate, and a WO3 / WO 3-x nanometer array layer is arranged on the surface of the carbon substrate, and the WO3 / WO 3-x nanometer array layer is loaded with a nitrite ion carrier; the reference electrode is a saturated calomel electrode; the counter electrode is a platinum sheet electrode; the carbon substrate is carbon cloth; the molecular formula of the nitrite ion carrier is C 36 H 46 N2CoO2, and the chemical structural formula is:
[0047] .
[0048] A preparation method of the working electrode, which comprises the following steps:
[0049] S1, hydrophilic treatment of the carbon cloth: the carbon cloth (CC) is sequentially ultrasonically cleaned in acetone, ethanol and deionized water for 10 min, then the carbon cloth is dried, and then the carbon cloth is immersed in a mixed acid solution for 12 h, taken out, washed with deionized water and dried for standby use; the mixed acid solution is obtained by mixing concentrated sulfuric acid and concentrated nitric acid; the frequency of the ultrasonic wave used in the ultrasonic cleaning is 25 KHz; the mixed acid solution is obtained by mixing concentrated sulfuric acid and concentrated nitric acid, and the volume ratio of the concentrated sulfuric acid and the concentrated nitric acid is 3:1. After the carbon cloth is treated by ultrasonic treatment in acetone, ethanol and deionized water to remove impurities on the surface of the carbon cloth, the carbon cloth is placed in the mixed acid solution prepared by mixing the concentrated sulfuric acid and the concentrated nitric acid in a certain proportion for treatment, so as to modify and treat the carbon cloth to be hydrophilic, which is helpful for subsequent loading of tungsten oxide;
[0050] S2, synthesis of the electrode WO3 / WO 3-x CC: sodium tungstate dihydrate and potassium oxalate monohydrate are dissolved in distilled water, and then the pH is adjusted to 1.6 by using 3M dilute hydrochloric acid, and then stirred for 2 h to obtain a precursor aqueous solution; tungsten hexachloride is dissolved in ethanol to obtain a tungsten hexachloride ethanol solution; the carbon cloth treated in step S1 is placed in a reaction kettle, then the precursor aqueous solution is poured into the reaction kettle, then the reaction kettle is sealed, and then the reaction is carried out at 190℃ for 11 h, then the carbon cloth is taken out, washed with ethanol and deionized water in sequence, and then dried at 60℃, and then placed in an annealing furnace at 560℃ for 2 h, and then cooled to room temperature, and then the carbon cloth is placed in the tungsten hexachloride ethanol solution, and then the reaction is carried out at 190℃ for 11 h, and then the carbon cloth is taken out, washed with ethanol and deionized water in sequence, and then dried at room temperature to obtain the electrode WO3 / WO 3-x—CC; each 1 L of aqueous precursor solution contains 0.05 mol of sodium tungstate dihydrate and 0.019 mol of potassium oxalate monohydrate; each 1 L of tungsten hexachloride ethanol solution contains 0.05 mol of tungsten hexachloride;
[0051] S3, preparation of nitrite ion carrier: o-phenylenediamine and 3,5-di-tert-butylsalicylaldehyde were dissolved in methanol to obtain reaction liquid A, each 1 L of reaction liquid A contains 0.17 mol of o-phenylenediamine and 0.33 mol of 3,5-di-tert-butylsalicylaldehyde, then formic acid was added to reaction liquid A and stirred at 90℃ for 12 h after mixing, the volume ratio of reaction liquid A and formic acid is 6000:4; the molar ratio of intermediate I and cobalt acetate tetrahydrate is 1:1, then the filter residue I was obtained by reduced pressure filtration, and the filter residue I was washed with ethanol and dried to obtain intermediate I; the obtained intermediate I was dissolved in chloroform to obtain reaction liquid B, each 1 L of reaction liquid B contains 0.08 mol of intermediate I; cobalt acetate tetrahydrate was dissolved in ethanol to obtain reaction liquid C, each 1 L of reaction liquid C contains 0.16 mol of cobalt acetate tetrahydrate; reaction liquid C was slowly added to reaction liquid B, after the addition was completed, it was stirred at room temperature for 3 h, then the filter residue II was obtained by reduced pressure filtration, and the filter residue II was washed with ethanol and dried to obtain the nitrite ion carrier.
[0052] S4, electrode WO3 / WO 3-x —3NN—CC: the nitrite ion carrier was dissolved in N,N-dimethylformamide (DMF), then an equal volume of Nafion solution was added and uniformly mixed to obtain a mixed liquid, the mixed liquid was added to the electrode WO3 / WO 3-x —CC obtained in step S2, then dried at room temperature for 24 h, then the mixed liquid was added to the electrode WO3 / WO 3-x —CC twice, and dried at room temperature for 24 h after each addition was completed to obtain the electrode WO3 / WO 3-x —3NN—CC, that is, the working electrode.
[0053] Example 4: A micro / nano electrochemical detection system for in-situ detection of nitrite, comprising the micro / nano electrochemical sensor for in-situ detection of nitrite described in Example 1, a polarization power supply 1, an ammeter 2, a voltmeter 3, and a supporting electrolyte 4, wherein the supporting electrolyte 4 is a 0.1M phosphate buffer solution (PBS, pH=6.5); the counter electrode 6 of the electrochemical sensor is electrically connected to the ammeter 2, and the ammeter 2 is electrically connected to the positive electrode of the polarization power supply 1; the reference electrode 5 of the electrochemical sensor is electrically connected to the voltmeter 3; the working electrode 7 of the electrochemical sensor is electrically connected to the negative electrodes of the voltmeter 3 and the polarization power supply 1, respectively; when the electrochemical detection system is in operation, the reference electrode 5, the counter electrode 6, and the working electrode 7 are placed in the same supporting electrolyte 4, and then the sample solution to be tested is added to the supporting electrolyte 4 for detection.
[0054] If sodium nitrite is added to the supporting electrolyte in multiple portions, and the nitrite ion concentration is measured, the results are as follows: Figures 5 to 8 The electrochemical detection system has a detection range of 0.2–21.7 μM and 0.02–15.2 mM for the electrochemical detection of nitrite ions, and the corresponding sensitivities are 500.3 μA / mM / cm², respectively. -2 and 600.7 μA mM cm -2 Moreover, it exhibits a linear relationship in the ranges of 0.2–21.7 μM and 0.02–15.2 mM, respectively (0.2–21.7 μM: y = 0.5003x + 0.04192, R). 2 =0.9996;0.02~15.2 mM:y=0.6008x+0.01682,R 2 =0.9999); meanwhile, the detection limit is 0.06 μM and the response time is 2 s;
[0055] For example, adding NO2-containing substances sequentially to the supporting electrolyte - 20 times the amount of NH4 + Fe 3+ Fe 2+ Ni 2+ Zn 2+ Co 2+ Cu 2+ Mg 2+ Solutions containing NO2 - 20 times the amount of CO3 2- NO3 - SO4 2- S2O8 2- C2O4 2- Solutions containing NO2 -, 20 times the amount of urea, sucrose, lactose, glycine, bovine serum albumin, sodium citrate solution, the test results are described in Figure 9 , the electrochemical detection system has good anti-interference ability when used for detecting nitrite ions.
[0056] Embodiment 5: A micro-nano electrochemical detection system for in-situ detection of nitrite salt, comprising the micro-nano electrochemical sensor for in-situ detection of nitrite salt described in Embodiment 2, an electrochemical workstation and a supporting electrolyte 4, the supporting electrolyte 4 is a phosphate buffer solution (PBS) with a concentration of 0.1M and a pH of 6.5; the counter electrode 6, the reference electrode 5 and the working electrode 7 of the electrochemical sensor are electrically connected with the electrochemical workstation; during the operation of the electrochemical detection system, the reference electrode 5, the counter electrode 6 and the working electrode 7 are placed in the same supporting electrolyte 4.
[0057] The utility model is not limited to the above-mentioned embodiment, the skilled person in the art can also make equivalent modification or replacement without departing from the spirit of the utility model, and these equivalent modifications or replacements are all included in the range defined by the claims of the present application.
Claims
1. A micro / nano electrochemical sensor for in-situ detection of nitrite, characterized in that: The electrochemical sensor comprises a reference electrode, a counter electrode, and a working electrode. The reference electrode is connected to the working electrode via a voltage measuring instrument to measure the potential of the working electrode relative to the reference electrode. The counter electrode is connected to the positive terminal of the polarization power supply. The working electrode is connected to the negative terminal of the polarization power supply, and the working electrode comprises a carbon substrate with WO3 / WO3 deposited on its surface. 3-x Nanoarray layer, the WO3 / WO 3-x The nanoarray layer is loaded with nitrite ion carriers.
2. The micro / nano electrochemical sensor for in-situ detection of nitrite according to claim 1, characterized in that: The reference electrode is a saturated calomel electrode; the counter electrode is a platinum sheet electrode.
3. The micro / nano electrochemical sensor for in-situ detection of nitrite according to claim 1, characterized in that: The carbon substrate is carbon cloth.
4. The micro / nano electrochemical sensor for in-situ detection of nitrite according to claim 1, characterized in that: The molecular formula of the nitrite ion carrier is C 36 H 46 N2CoO2.
5. A micro-nano electrochemical detection system for in-situ detection of nitrite, characterized in that, The electrochemical detection system comprises a micro / nano electrochemical sensor for in-situ detection of nitrite as described in any one of claims 1 to 4, a polarization power supply (1), an ammeter (2), a voltmeter (3), and a supporting electrolyte (4), wherein the supporting electrolyte (4) is a phosphate buffer solution with a concentration of 0.1 M; the counter electrode (6) of the electrochemical sensor is electrically connected to the ammeter (2), and the ammeter (2) is electrically connected to the positive electrode of the polarization power supply (1); the reference electrode (5) of the electrochemical sensor is electrically connected to the voltmeter (3); the working electrode (7) of the electrochemical sensor is electrically connected to the negative electrode of the voltmeter (3) and the polarization power supply (1), respectively; when the electrochemical detection system is in operation, the reference electrode (5), the counter electrode (6), and the working electrode (7) are placed in the same supporting electrolyte (4).
6. A micro-nano electrochemical detection system for in-situ detection of nitrite, characterized in that: The electrochemical detection system includes a micro / nano electrochemical sensor for in-situ detection of nitrite as described in any one of claims 1 to 4, an electrochemical workstation, and a supporting electrolyte (4), wherein the supporting electrolyte (4) is a phosphate buffer solution with a concentration of 0.1 M; the counter electrode (6), reference electrode (5), and working electrode (7) of the electrochemical sensor are electrically connected to the electrochemical workstation; when the electrochemical detection system is in operation, the reference electrode (5), counter electrode (6), and working electrode (7) are placed in the same supporting electrolyte (4).