Electrochemical sensor for detecting glucose and detection method

Abstract

The present invention provides a zinc-cobalt sulfide bimetallic organic framework material, a preparation method thereof, and an application in the electrochemical detection of glucose, belonging to the technical field of glucose detection. In the present invention, Zn itself has a certain electrochemical catalytic effect, but due to the limited active sites and insufficient orbits in the Zn organic framework material, it has limitations in the application of electrochemical detection. The present invention uses Zn and Co as the double coordination metals of the organic framework material. The addition of Co can replace the position of the original Zn, so that Zn is more exposed on the surface of the organic framework material, thereby improving the catalytic activity. Through the sulfurization reaction, the zinc-cobalt bimetallic organic framework material of the present invention forms a hollow structure during the sulfurization process, has a larger specific surface area, can provide more catalytic active sites, and the electronegativity of S is lower, which can reduce the collapse of the organic framework material structure and maintain the stability of the material structure.

Description

Technical Field

[0001] The present invention relates to the technical field of glucose detection, and in particular to a zinc cobalt sulfide bimetallic organic framework material, a preparation method thereof, and an application thereof in electrochemical detection of glucose. Background Art

[0002] Glucose is an organic compound that is a source of energy for living cells and a metabolic intermediate, making it the primary energy source for living organisms. Currently, glucose is widely used in the fermentation, food, chemical, and medical industries.

[0003] Over the past few decades, numerous glucose detection methods have been reported, including liquid chromatography, gas chromatography, mass spectrometry, fluorescence, electrochemistry, and capillary electrophoresis. Among them, electrochemical techniques have attracted considerable attention due to their low cost, short analysis time, ease of operation, high sensitivity, high selectivity, and suitability for real-time detection. Generally speaking, glucose electrochemical sensors can be divided into two categories: enzyme-based and non-enzyme-based. Enzyme-based sensors offer high specificity, sensitivity, and a wide response range. However, these sensors are expensive, and the catalytic activity of the enzyme can be affected by environmental factors such as temperature, pH, and humidity.

[0004] In recent years, non-enzymatic electrochemical glucose sensors have become a hot research area, overcoming the major shortcomings of existing enzyme-based sensors. Currently, noble metal catalysts such as gold, silver, platinum, and their alloys are considered the best performing non-enzymatic electrochemical sensing materials. However, despite their high electrocatalytic activity for glucose oxidation, their high cost has limited their widespread application. Summary of the Invention

[0005] In view of this, the present invention aims to provide a zinc-cobalt sulfide bimetallic organic framework material, its preparation method, and its application in electrochemical detection of glucose. The zinc-cobalt sulfide bimetallic organic framework material provided by the present invention is low in cost and has good electrocatalytic oxidation activity for glucose.

[0006] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0007] The present invention provides a method for preparing a zinc cobalt sulfide bimetallic organic framework material, comprising the following steps:

[0008] mixing a soluble zinc salt, a soluble divalent cobalt salt, 2-methylimidazole and a first dispersing solvent, and performing a coordination reaction to obtain a zinc-cobalt bimetallic organic framework material;

[0009] The zinc-cobalt bimetallic organic framework material is mixed with sulfide and a second dispersing solvent, and a sulfurization reaction is performed to obtain a zinc-cobalt sulfide bimetallic organic framework material.

[0010] Preferably, the molar ratio of zinc ions in the soluble zinc salt to cobalt ions in the soluble divalent cobalt salt is 2:1 to 4;

[0011] The ratio of the sum of the amounts of the soluble zinc salt and the soluble cobalt salt to the amount of 2-methylimidazole is 1:2-4.

[0012] Preferably, the sulfide is one or more of thioacetamide, sodium sulfide and thiourea.

[0013] Preferably, the molar ratio of the zinc-cobalt bimetallic organic framework material to the sulfide is 1:2-5.

[0014] Preferably, the temperature of the vulcanization reaction is 80-180° C., and the time is 3-12 hours.

[0015] The present invention provides a zinc-cobalt sulfide bimetallic organic framework material prepared by the above preparation method. The organic ligand of the zinc-cobalt sulfide bimetallic organic framework material is 2-methylimidazole, and the coordination metals are zinc sulfide and cobalt sulfide.

[0016] Preferably, the particle size of the zinc cobalt sulfide bimetallic organic framework material is 100 to 500 nm.

[0017] The present invention provides application of the zinc cobalt sulfide bimetallic organic framework material in electrochemical detection of glucose.

[0018] The present invention provides an electrochemical sensor for detecting glucose, comprising a working electrode, a counter electrode, a reference electrode and an electrolyte, and is characterized in that the electrode material of the working electrode comprises the above-mentioned zinc sulfide cobalt bimetallic organic framework material.

[0019] The present invention provides a method for electrochemically detecting glucose, comprising the following steps:

[0020] The sample to be tested is added to the electrolyte of the above electrochemical sensor, and a cyclic voltammetry test is performed using a three-electrode system consisting of a working electrode, a counter electrode, and a reference electrode to obtain the oxidation peak of the cyclic voltammetry curve;

[0021] Obtaining the glucose content in the sample to be tested according to the oxidation peak and a predetermined standard curve;

[0022] The standard curve is a linear relationship curve between glucose concentration and oxidation peak value of cyclic voltammetry curve.

[0023] The present invention provides a method for preparing a zinc-cobalt sulfide bimetallic organic framework material, comprising the following steps: mixing a soluble zinc salt, a soluble divalent cobalt salt, 2-methylimidazole, and a first dispersing solvent, performing a coordination reaction, and obtaining a zinc-cobalt bimetallic organic framework material; and mixing the zinc-cobalt bimetallic organic framework material with a sulfide and a second dispersing solvent, and performing a sulfurization reaction, to obtain a zinc-cobalt sulfide bimetallic organic framework material. The present invention utilizes a coordination reaction to synthesize an organic framework material containing a zinc-cobalt bimetallic, and then performs a sulfurization reaction to obtain the zinc-cobalt bimetallic organic framework material. In the present invention, Zn itself has a certain electrochemical catalytic effect, but due to the limited active sites and insufficient orbitals in the Zn organic framework material, it has limitations in its application in electrochemical detection. The present invention uses Zn and Co as the dual coordination metals of the organic framework material. The addition of Co can displace the original Zn position, exposing more Zn on the surface of the organic framework material and enhancing catalytic activity. The present invention utilizes a sulfurization reaction to form a hollow structure in the zinc-cobalt bimetallic organic framework material. This structure increases the specific surface area and provides more catalytically active sites. Furthermore, the lower electronegativity of sulfur reduces structural collapse of the organic framework material and maintains its stability. Furthermore, the preparation method provided by the present invention is simple and uses low-cost raw materials, facilitating industrial mass production and market application.

[0024] The present invention provides the use of the aforementioned zinc-cobalt sulfide bimetallic organic framework material in the electrochemical detection of glucose. The zinc-cobalt sulfide bimetallic organic framework material provided herein, based on an organic framework, can be used for glucose sensing, enabling rapid and convenient glucose detection while exhibiting excellent stability and being unaffected by environmental factors, pH, and temperature. Experimental results demonstrate that the zinc-cobalt sulfide bimetallic organic framework material provided herein has a detection limit for glucose as low as 0.1 μM. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is an SEM image of the zinc-cobalt sulfide bimetallic organic framework material obtained in Example 1;

[0026] Figure 2 CV curves of the electrochemical sensor obtained in Example 1 in different electrolytes;

[0027] Figure 3 1 is the linear relationship curve of the oxidation peak of the electrochemical sensor of Example 1 for glucose solutions with different concentrations;

[0028] Figure 4 This is an SEM image of the zinc-cobalt sulfide bimetallic organic framework material obtained in Example 2;

[0029] Figure 5 CV curves of the electrochemical sensor obtained in Example 2 in different electrolytes;

[0030] Figure 6 : This is the linear relationship curve of the oxidation peak of the electrochemical sensor in Example 2 for glucose solutions with different concentrations;

[0031] Figure 7 This is the SEM image of the zinc cobalt sulfide bimetallic organic framework material obtained in Example 3

[0032] Figure 8 CV curves of the electrochemical sensor obtained in Example 3 in different electrolytes

[0033] Figure 9 3 is the linear relationship curve of the oxidation peak of the electrochemical sensor of Example 3 for glucose solutions with different concentrations;

[0034] Figure 10 This is the SEM image of the zinc-cobalt sulfide bimetallic organic framework material obtained in Comparative Example 1;

[0035] Figure 11 CV curves of the electrochemical sensor obtained in Comparative Example 1 in different electrolytes;

[0036] Figure 12 This is the SEM image of the zinc-cobalt sulfide bimetallic organic framework material obtained in Comparative Example 2;

[0037] Figure 13 CV curves of the electrochemical sensor obtained in Comparative Example 2 in different electrolytes. DETAILED DESCRIPTION

[0038] The present invention provides a method for preparing a zinc cobalt sulfide bimetallic organic framework material, comprising the following steps:

[0039] mixing a soluble zinc salt, a soluble divalent cobalt salt, 2-methylimidazole and a first dispersing solvent, and performing a coordination reaction to obtain a zinc-cobalt bimetallic organic framework material;

[0040] The zinc-cobalt bimetallic organic framework material is mixed with sulfide and a second dispersing solvent, and a sulfurization reaction is performed to obtain a zinc-cobalt sulfide bimetallic organic framework material.

[0041] The present invention mixes a soluble zinc salt, a soluble divalent cobalt salt, 2-methylimidazole, and a first dispersing solvent, and performs a coordination reaction to obtain a zinc-cobalt bimetallic organic framework material. In the present invention, the soluble zinc salt is preferably one or more of zinc nitrate hexahydrate, zinc chloride dihydrate, and zinc sulfate heptahydrate; and the soluble divalent cobalt salt is preferably one or more of cobalt nitrate hexahydrate, cobalt chloride dihydrate, and cobalt sulfate heptahydrate.

[0042] In the present invention, the molar ratio of zinc ions in the soluble zinc salt to cobalt ions in the soluble divalent cobalt salt is preferably 2:1 to 4, more preferably 2:3 to 4;

[0043] The ratio of the sum of the amounts of the soluble zinc salt and the soluble cobalt salt to the amount of 2-methylimidazole is preferably 1:2 to 4, more preferably 1:3.

[0044] In the present invention, the first dispersing solvent is preferably a polar organic solvent or water. In the present invention, the polar organic solvent is preferably methanol and / or dimethylformamide.

[0045] In the present invention, the mixing is preferably stirring. In the present invention, the mixing is preferably carried out by mixing the soluble zinc salt, the soluble divalent cobalt salt and the first dispersing solvent to obtain a metal salt solution;

[0046] mixing 2-methylimidazole with a first dispersing solvent to obtain a 2-methylimidazole solution;

[0047] The metal salt solution and the 2-methylimidazole solution were mixed.

[0048] In the present invention, the coordination reaction is preferably carried out under static conditions. In the present invention, the coordination reaction temperature is preferably room temperature, and the time is preferably 14 to 24 hours, more preferably 16 to 20 hours.

[0049] After the coordination reaction, the present invention preferably performs post-treatment on the obtained coordination reaction solution. In the present invention, the post-treatment includes:

[0050] The coordination reaction liquid is subjected to solid-liquid separation, and the obtained solid ethylene is washed and dried to obtain a pure product of the zinc-cobalt bimetallic organic framework material.

[0051] In the present invention, the solid-liquid separation method is preferably filtration. In the present invention, the detergent used in the washing is preferably methanol, and the number of washings is preferably 3 times. In the present invention, the drying is preferably vacuum drying; and the drying temperature is preferably 60°C.

[0052] After obtaining the zinc-cobalt bimetallic organic framework material, the present invention mixes the zinc-cobalt bimetallic organic framework material with sulfide and a second dispersing solvent to perform a sulfurization reaction to obtain a zinc-cobalt sulfide bimetallic organic framework material.

[0053] In the present invention, the sulfide is preferably one or more of thioacetamide, sodium sulfide and thiourea.

[0054] In the present invention, the mass ratio of the zinc-cobalt bimetallic organic framework material to the sulfide is preferably 1:2-5, more preferably 1:3-4.

[0055] In the present invention, the second dispersing solvent is preferably ethanol and water; in the present invention, the volume ratio of ethanol to water is preferably 1 to 4:1, more preferably 2 to 3:1.

[0056] In the present invention, the mixing method is preferably stirring and mixing.

[0057] In the present invention, the vulcanization reaction is preferably carried out in a polytetrafluoroethylene autoclave. In the present invention, the vulcanization reaction temperature is preferably 80-180°C, more preferably 100-150°C; and the reaction time is preferably 3-12 hours, more preferably 5-10 hours.

[0058] In the present invention, after the sulfurization reaction, the present invention preferably performs post-treatment on the obtained sulfurization reaction liquid. In the present invention, the post-treatment preferably includes:

[0059] The sulfidation reaction liquid is subjected to solid-liquid separation, and the obtained solid is washed and dried in sequence to obtain a pure zinc cobalt sulfide bimetallic organic framework material.

[0060] In the present invention, the solid-liquid separation method is preferably filtration. In the present invention, the washing detergent is preferably ethanol and water. The present invention has no special requirements for the drying method, and a drying method well known to those skilled in the art can be used.

[0061] The present invention provides a zinc-cobalt sulfide bimetallic organic framework material prepared by the above preparation method. The organic ligand of the zinc-cobalt sulfide bimetallic organic framework material is 2-methylimidazole, and the coordination metals are zinc sulfide and cobalt sulfide.

[0062] In the present invention, the molar ratio of zinc sulfide to cobalt sulfide is preferably 1:2.

[0063] In the present invention, the particle size of the zinc cobalt sulfide bimetallic organic framework material is preferably 100 to 500 nm, more preferably 200 nm.

[0064] The present invention provides the use of the zinc-cobalt sulfide bimetallic organic framework material in the electrochemical detection of glucose. In the present invention, the zinc-cobalt sulfide bimetallic organic framework material can be used as an electrode material for electrochemical detection of glucose.

[0065] The present invention provides an electrochemical sensor for detecting glucose, comprising a working electrode, a counter electrode, a reference electrode and an electrolyte. The electrode material of the working electrode comprises the above-mentioned zinc cobalt sulfide bimetallic organic framework material, and preferably also comprises a binder and water. The binder is preferably polyvinylidene fluoride.

[0066] In the present invention, the mass ratio of the zinc cobalt sulfide bimetallic organic framework material, the binder and water is preferably 5 to 10:1:1, more preferably 6 to 8:1:1.

[0067] In the present invention, the method for preparing the working electrode preferably comprises the following steps:

[0068] The zinc cobalt sulfide bimetallic organic framework material, a binder and water are mixed and ground to obtain an electrolytic material;

[0069] The electrode material is coated on the surface of the electrode substrate and pressed into tablets to obtain a working electrode.

[0070] In the present invention, the electrode substrate is preferably nickel foam.

[0071] In the present invention, the counter electrode is preferably a platinum electrode, and the reference electrode is preferably a saturated calomel electrode.

[0072] In the present invention, the electrolyte is preferably an inorganic strong base solution. In the present invention, the inorganic strong base is preferably KOH and / or NaOH. In the present invention, the molar concentration of the inorganic strong base solution is preferably 0.1 to 5 mol / L, more preferably 0.5 to 2 mol / L.

[0073] The present invention provides a method for electrochemically detecting glucose, comprising the following steps:

[0074] Adding the sample to be tested into the electrolyte of the electrochemical sensor, performing a cyclic voltammetry test on the electrochemical sensor, and obtaining an oxidation peak of the cyclic voltammetry curve;

[0075] Obtaining the glucose content in the sample to be tested according to the oxidation peak and a predetermined standard curve;

[0076] The standard curve is a linear relationship curve between glucose concentration and oxidation peak value of cyclic voltammetry curve.

[0077] The present invention adds the sample to be tested to the electrolyte of the electrochemical sensor, and performs cyclic voltammetry using a three-electrode system consisting of a working electrode, a counter electrode, and a reference electrode to obtain the oxidation peak of the cyclic voltammetry curve. In the present invention, the sample to be tested is preferably a liquid containing glucose.

[0078] In the present invention, the electrochemical window of the cyclic voltammetry test is preferably -0.5V to 0.8V, and the scan rate is preferably 50mV / s.

[0079] In the present invention, the added volume of the sample to be tested is preferably 5 to 20 mg, more preferably 10 to 15 mg.

[0080] In the present invention, the method for drawing the standard curve preferably includes the following steps:

[0081] Provide a gradient of glucose solutions with known concentrations;

[0082] The glucose solution with a gradient of known concentration is used as a sample to be tested, and the glucose solution with a gradient of known concentration is added to the electrolyte of the electrochemical sensor respectively. A cyclic voltammetry test is performed on the electrochemical sensor to obtain the oxidation peak of the cyclic voltammetry curve corresponding to the glucose solution with a gradient of known concentration. A standard curve is drawn with the concentration of the glucose solution as the horizontal axis and the oxidation peak of the cyclic voltammetry curve as the vertical axis.

[0083] In the present invention, the linear detection range of the standard curve is preferably 3-9 μM and 10 μM-0.1 mM. In the present invention, the detection limit of glucose is preferably 0.1 μM.

[0084] The zinc cobalt sulfide bimetallic organic framework material provided by the present invention, its preparation method and its application in electrochemical detection of glucose are described in detail below with reference to the examples, but they should not be construed as limiting the scope of protection of the present invention.

[0085] Example 1

[0086] Zn(NO3)2·6(H2O) (zinc nitrate hexahydrate) and Co(NO3)2·6(H2O) (cobalt nitrate hexahydrate) were uniformly dispersed in a 25 mL methanol solution at a molar ratio of 1:2 to obtain a zinc-cobalt metal salt mixed solution. Zinc-cobalt metal salt and 2-MI (2-methylimidazole) were dispersed in a 25 mL methanol solution at a molar ratio of 1:2 to obtain an organic ligand solution. The two were mixed and stirred thoroughly, then allowed to settle for 14 hours to obtain a purple product. The resulting product was washed three times with methanol and then dried in vacuo at 60°C to obtain the ZnCo-MOF material.

[0087] ZnCo-MOF and TAA (thioacetamide) were thoroughly mixed in 40 mL of EtOH (anhydrous ethanol) and 20 mL of deionized water in a mass ratio of 1:4. After stirring, the mixture was transferred to a polytetrafluoroethylene autoclave and reacted at 80°C for 8 hours to obtain a black product. The obtained black product was washed with deionized water and ethanol and then dried in vacuo at 60°C to obtain a zinc cobalt sulfide bimetallic organic framework material.

[0088] The SEM image of the obtained zinc cobalt sulfide bimetallic organic framework material is shown in Figure 1 As shown. Figure 1 It can be seen that the zinc-cobalt sulfide bimetallic organic framework material obtained in the present invention has a regular dodecahedral structure, a size of about 200 nm, a large specific surface area and a large number of active sites.

[0089] The obtained zinc cobalt sulfide bimetallic organic framework material, deionized water, and PVDF were thoroughly mixed and ground in a mass ratio of 3:1:1, smeared on a 1×1 cm nickel foam and pressed into a sheet. This was used as the working electrode, a platinum sheet was used as the counter electrode, and a saturated calomel electrode was used as the reference electrode to form an electrochemical sensor with a three-electrode system. 0.1 M KOH was used as the electrolyte. During the cyclic voltammetry test, the electrochemical window was selected as -0.5 V to 0.8 V, and the scan rate was 50 mV / s.

[0090] The CV curves of the obtained electrochemical sensor in different electrolytes are shown in Figure 2. Figure 2 As shown. Figure 2 It can be seen that its oxidation peak in the electrolyte containing 4 mM glucose solution is significantly enhanced.

[0091] The linear relationship curve of the electrochemical sensor for the oxidation peak of glucose solution with different concentrations is as follows: Figure 3 As shown. Figure 3 The linear relationship between the oxidation peak and glucose concentration shows two linear relationships: within the 3μM to 9μM and 10μM to 0.1mM ranges, respectively. Within the 3μM to 9μM range, the linear relationship curve is y1 = 26.5x + 6.589, R1 = 99989; within the 10μM to 0.1mM range, y2 = 2.498x + 6.869, R2 = 0.99359. Furthermore, the detection limit for glucose is as low as 0.1μM. This demonstrates that the zinc-cobalt sulfide bimetallic organic framework material provided by the present invention has a good catalytic effect on glucose and can be used as a glucose sensing material.

[0092] Example 2

[0093] ZnCl2·2H2O (zinc chloride dihydrate) and CoCl2·2H2O (cobalt chloride dihydrate) were uniformly dispersed in a 20 mL methanol solution at a molar ratio of 1:2 to obtain a zinc-cobalt metal salt mixed solution. Zinc-cobalt metal salt and 2-MI (2-methylimidazole) were dispersed in a 20 mL methanol solution at a molar ratio of 1:3 to obtain an organic ligand solution. The two were mixed and stirred thoroughly, then allowed to settle for 18 hours to obtain a purple product. The resulting product was washed three times with methanol and then dried in vacuo at 60°C to obtain the ZnCo-MOF material.

[0094] ZnCo-MOF and CH4N2S (thiourea) were thoroughly mixed in 40 mL of EtOH (anhydrous ethanol) and 10 mL of deionized water in a mass ratio of 1:2. After stirring, the mixture was transferred to a polytetrafluoroethylene autoclave and reacted at 120°C for 6 hours to obtain a black product. The resulting black product was washed with deionized water and ethanol and then dried in vacuo at 60°C to obtain a zinc cobalt sulfide bimetallic organic framework material.

[0095] The SEM image of the obtained zinc cobalt sulfide bimetallic organic framework material is shown in Figure 4 As shown. Figure 4 It can be seen that the zinc-cobalt sulfide bimetallic organic framework material obtained in the present invention has a regular dodecahedral structure, a size of about 200 nm, a large specific surface area and a large number of active sites.

[0096] The obtained zinc cobalt sulfide bimetallic organic framework material was prepared into an electrochemical sensor in the manner of Example 1. Glucose was added and its redox CV curve was observed. The CV curves of the obtained electrochemical sensor in different electrolytes are as follows: Figure 5 As shown. Figure 5 It can be seen that its oxidation peak in the electrolyte containing 4 mM glucose solution is significantly enhanced.

[0097] The linear relationship curve of the electrochemical sensor for the oxidation peak of glucose solution with different concentrations is as follows: Figure 6 As shown. Figure 6 The linear relationship between the oxidation peak and glucose concentration shows two linear relationships: within the 3μM to 9μM and 10μM to 0.1mM ranges, respectively. Within the 3μM to 9μM range, the linear relationship curve is y1 = 24x + 6.67, R1 = 0.9987; within the 10μM to 0.1mM range, y2 = 2.56x + 6.554, R2 = 0.9925. Furthermore, the detection limit for glucose is as low as 0.1μM. This demonstrates that the zinc-cobalt sulfide bimetallic organic framework material provided by the present invention has a good catalytic effect on glucose and can be used as a glucose sensing material.

[0098] Example 3

[0099] ZnH 14 O 11 S (zinc sulfate heptahydrate), CoH 14 O 11S (cobalt sulfate heptahydrate) was evenly dispersed in 40 mL of Meth (methanol) solution at a molar ratio of 1:2 to obtain a zinc-cobalt metal salt mixed solution. Zinc-cobalt metal salt and 2-MI (2-methylimidazole) were dispersed in 40 mL of Meth (methanol) solution at a molar ratio of 1:4 to obtain an organic ligand solution. The two were mixed and stirred thoroughly, and then allowed to settle for 24 hours to obtain a purple product. The obtained product was washed three times with Meth (methanol) and vacuum dried at 60°C to obtain ZnCo-MOF material.

[0100] ZnCo-MOF and Na2S·2H2O were thoroughly mixed in 30 mL of EtOH (anhydrous ethanol) and 30 mL of deionized water at a mass ratio of 1:5. After stirring, the mixture was transferred to a polytetrafluoroethylene autoclave and reacted at 180°C for 3 hours to obtain a black product. The resulting black product was washed with deionized water and ethanol and then dried in vacuo at 60°C to obtain a zinc cobalt sulfide bimetallic organic framework material.

[0101] The SEM image of the obtained zinc cobalt sulfide bimetallic organic framework material is shown in Figure 7 As shown. Figure 7 It can be seen that the zinc-cobalt sulfide bimetallic organic framework material obtained in the present invention has a regular dodecahedral structure, a size of about 200 nm, a large specific surface area and a large number of active sites.

[0102] The obtained zinc cobalt sulfide bimetallic organic framework material was prepared into an electrochemical sensor in the manner of Example 1. Glucose was added and its redox CV curve was observed. The CV curves of the obtained electrochemical sensor in different electrolytes are as follows: Figure 8 As shown. Figure 8 It can be seen that its oxidation peak in the electrolyte containing 4 mM glucose solution is significantly enhanced.

[0103] The linear relationship curve of the electrochemical sensor for the oxidation peak of glucose solution with different concentrations is as follows: Figure 9 As shown. Figure 9 The linear relationship between the oxidation peak and glucose concentration shows two linear relationships: within the ranges of 3μM to 9μM and 10μM to 0.1mM. Within the range of 3μM to 9μM, the linear relationship curve is y1 = 22x + 5.84, R1 = 0.9974; within the range of 10μM to 0.1mM, y2 = 2.21x + 5.628, R2 = 0.9912. Furthermore, the detection limit for glucose is as low as 0.1μM. This demonstrates that the zinc-cobalt sulfide bimetallic organic framework material provided by the present invention has a good catalytic effect on glucose and can be used as a glucose sensing material.

[0104] Comparative Example 1

[0105] ZnCl2·2H2O (zinc chloride dihydrate) and CoCl2·2H2O (cobalt chloride dihydrate) were uniformly dispersed in 30 mL of DMF (dimethylformamide) solution at a molar ratio of 1:1 to obtain a zinc-cobalt metal salt mixed solution. Zinc-cobalt metal salt and 2-MI (2-methylimidazole) were dispersed in 30 mL of DMF (dimethylformamide) solution at a molar ratio of 1:3 to obtain an organic ligand solution. The two were mixed and stirred thoroughly, and then allowed to settle for 6 hours to obtain a purple product. The obtained product was washed four times with DMF (dimethylformamide) and then vacuum dried at 40°C to obtain the ZnCo-MOF material.

[0106] ZnCo-MOF and CH4N2S (thiourea) were thoroughly mixed in 60 mL of deionized water at a molar ratio of 1:2. After stirring, the mixture was transferred to a polytetrafluoroethylene autoclave and reacted at 180°C for 3 hours to obtain a black product. The resulting black product was washed with deionized water and dried in vacuo at 40°C to obtain a zinc cobalt sulfide bimetallic organic framework material.

[0107] The SEM image of the obtained zinc cobalt sulfide bimetallic organic framework material is shown in Figure 10 As shown. Figure 10 It can be seen that the morphology of the obtained zinc cobalt sulfide bimetallic organic framework material is irregular block-like, and its specific surface area and voids are small.

[0108] The obtained zinc cobalt sulfide bimetallic organic framework material was prepared into an electrochemical sensor in the manner of Example 1. Glucose was added and its redox CV curve was observed. Figure 11 As shown in Figure 2, it can be seen that the CV curve of its redox does not change and has no linear relationship.

[0109] Comparative Example 2

[0110] ZnH 14 O 11 S (zinc sulfate heptahydrate), CoH 14 O 11 S (cobalt sulfate heptahydrate) was uniformly dispersed in 40 mL of deionized water at a molar ratio of 2:1 to obtain a zinc-cobalt metal salt mixed solution. Zinc-cobalt metal salt and 2-MI (2-methylimidazole) were dispersed in 40 mL of deionized water at a molar ratio of 1:4 to obtain an organic ligand solution. The two were mixed and stirred thoroughly, then allowed to settle for 24 hours to obtain a purple product. The resulting product was washed three times with deionized water and vacuum-dried at 50°C to obtain the ZnCo-MOF nanomaterial.

[0111] Thoroughly mix ZnCo-MOF and Na2S·2H2O dihydrate sodium sulfide in a molar ratio of 1:3

[0112] After stirring in 40 mL of deionized water, the mixture was transferred to a polytetrafluoroethylene autoclave and reacted at 120°C for 12 hours to obtain a black product. The resulting black product was washed with deionized water and vacuum-dried at 50°C to obtain a zinc cobalt sulfide bimetallic organic framework material.

[0113] The SEM image of the obtained zinc cobalt sulfide bimetallic organic framework material is shown in Figure 12 .Depend on Figure 12 It can be seen that the morphology of the obtained zinc cobalt sulfide bimetallic organic framework material is irregular block-like, and its specific surface area and voids are small.

[0114] The obtained zinc cobalt sulfide bimetallic organic framework material was prepared into an electrochemical sensor in the manner of Example 1. Glucose was added and its redox CV curve was observed. Figure 13 As shown in Figure 2, it can be seen that the CV curve of its redox does not change and has no linear relationship.

[0115] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. An electrochemical sensor for detecting glucose, comprising a working electrode, a counter electrode, a reference electrode and an electrolyte, characterized in that: The electrode material of the working electrode is a zinc cobalt sulfide bimetallic organic framework material; the organic ligand of the zinc cobalt sulfide bimetallic organic framework material is 2-methylimidazole, and the coordination metals are zinc sulfide and cobalt sulfide; The preparation method of the zinc cobalt sulfide bimetallic organic framework material comprises the following steps: A soluble zinc salt, a soluble divalent cobalt salt, 2-methylimidazole and a first dispersing solvent are mixed and subjected to a coordination reaction to obtain a zinc-cobalt bimetallic organic framework material; the molar ratio of zinc ions in the soluble zinc salt to cobalt ions in the soluble divalent cobalt salt is 1:2; and the ratio of the sum of the amounts of the soluble zinc salt and the soluble cobalt salt to the amount of 2-methylimidazole is 1:2-3; Mixing the zinc-cobalt bimetallic organic framework material with sulfide and a second dispersing solvent to perform a sulfurization reaction to obtain a zinc-cobalt sulfide bimetallic organic framework material; The zinc cobalt sulfide bimetallic organic framework material has a particle size of 200 nm and presents a regular dodecahedral structure.

2. The electrochemical sensor for detecting glucose according to claim 1, characterized in that: The sulfide is one or more of thioacetamide, sodium sulfide and thiourea.

3. The electrochemical sensor for detecting glucose according to claim 1, wherein The mass ratio of the zinc-cobalt bimetallic organic framework material to the sulfide is 1:2-5.

4. The electrochemical sensor for detecting glucose according to claim 1, wherein The temperature of the vulcanization reaction is 80-180° C., and the time is 3-12 hours.

5. A method for electrochemically detecting glucose, comprising the following steps: Adding the sample to be tested into the electrolyte of the electrochemical sensor according to any one of claims 1 to 4, performing a cyclic voltammetry test using a three-electrode system consisting of a working electrode, a counter electrode, and a reference electrode to obtain an oxidation peak of the cyclic voltammetry curve; Obtaining the glucose content in the sample to be tested according to the oxidation peak and a predetermined standard curve; The standard curve is a linear relationship curve between glucose concentration and oxidation peak value of cyclic voltammetry curve.

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