A cobalt-based heterojunction nanocomposite material and its preparation method and application

Abstract

The present invention provides a cobalt-based heterojunction nanocomposite material, a preparation method thereof, and an application thereof, belonging to the technical field of composite materials. The present invention obtains a cobalt-based heterojunction nanocomposite material by adopting a method of pyrolysis oxidation treatment assisted by borohydride salt reduction. The composite material uses two-dimensional Co3O4 nanosheets as a carrier, inherits the advantage of large specific surface area of ​​ZIF-67 nanosheets, and at the same time, the metal cation and oxygen anion defects in the cobalt-based heterojunction nanocomposite material make the cobalt-based heterojunction nanocomposite material have abundant active sites, which provides a great advantage for electron transfer and small molecule adsorption; at the same time, the formation of the heterojunction interface can further improve the conductivity of the cobalt-based heterojunction nanocomposite material, and it is used as a modified material to prepare a working electrode for photoelectrochemical detection of glucose, which exhibits excellent detection sensitivity and good photoelectric response.

Description

Technical Field

[0001] The present invention relates to the technical field of composite materials, and in particular to a cobalt-based heterojunction nanocomposite material and a preparation method and application thereof. Background Art

[0002] Glucose is an essential nutrient for human life, serving not only as an energy source but also as a metabolic intermediate. However, excessive levels of glucose in the blood can be detrimental to human health, potentially leading to diabetes and other complications. Accurate and rapid monitoring of glucose levels is essential to overcome the health risks associated with diabetes.

[0003] Currently, a variety of methods are used for glucose detection, including inductively coupled plasma mass spectrometry, fluorescence, X-ray fluorescence spectroscopy, and electrochemical detection. Among them, electrochemical detection has attracted widespread attention for small biomolecule detection due to its high sensitivity, fast response, low detection limit, and good selectivity.

[0004] Precious metal materials show great promise in the electrochemical detection of glucose, but their high cost limits their further use. Transition metal oxide semiconductor-modified electrode materials, such as Co₃O₄, Fe₃O₄, and NiO, are widely used in the electrochemical detection of glucose due to their environmental friendliness, low cost, and significant activity. However, the poor conductivity and limited active sites of transition metal oxides limit their further development, resulting in poor sensitivity in the electrochemical detection of glucose. Summary of the Invention

[0005] The object of the present invention is to provide a method for preparing a cobalt-based heterojunction nanocomposite material. The cobalt-based heterojunction nanocomposite material prepared by the method shows excellent sensitivity when used for photoelectrochemical detection of 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 cobalt-based heterojunction nanocomposite material, comprising the following steps:

[0008] The ZIF-67 nanosheets were pyrolyzed and oxidized to obtain two-dimensional Co3O4 nanosheets;

[0009] The two-dimensional Co3O4 nanosheets are mixed with a cationic surfactant, water, a soluble metal salt and a borohydride salt, and a reduction reaction is performed to obtain a cobalt-based heterojunction nanocomposite material; the soluble metal salt includes a soluble salt of copper or nickel.

[0010] Preferably, the pyrolysis oxidation treatment is a microwave carbon bath.

[0011] Preferably, the microwave power of the microwave carbon bath is 560 to 800 W; the time of the microwave carbon bath is 10 to 40 minutes; and the burial depth of the microwave carbon bath is -2.0 to +2.0 cm.

[0012] Preferably, the borohydride salt comprises sodium borohydride or potassium borohydride.

[0013] Preferably, in the step, the molar ratio of the cobalt ions in the two-dimensional Co3O4 nanosheets, the metal ions in the soluble metal salt and the borohydride ions in the borohydride salt is (0.2-1):1:(5-20).

[0014] The present invention also provides a cobalt-based heterojunction nanocomposite material prepared by the preparation method of the above technical solution, comprising a two-dimensional porous nanosheet and nanoparticles loaded on the two-dimensional porous nanosheet, wherein the two-dimensional porous nanosheet is a two-dimensional Co3O4 nanosheet, and the nanoparticles include nickel particles or Cu and Cu 2+1 O particles formed.

[0015] Preferably, the particle size of the nanoparticles is 50 to 300 nm.

[0016] Preferably, the thickness of the two-dimensional porous nanosheet is 20-100 nm.

[0017] The present invention also provides a working electrode, which includes a substrate and a modifying material coated on the substrate, wherein the modifying material includes the cobalt-based heterojunction nanocomposite material described in the above technical solution.

[0018] The present invention also provides the use of the working electrode described in the above technical solution in photoelectrochemical detection of glucose.

[0019] The present invention provides a method for preparing a cobalt-based heterojunction nanocomposite material, comprising the following steps: subjecting ZIF-67 nanosheets to a pyrolytic oxidation treatment to obtain two-dimensional Co3O4 nanosheets; mixing the two-dimensional Co3O4 nanosheets with a cationic surfactant, water, a soluble metal salt, and a borohydride salt, and performing a reduction reaction to obtain a cobalt-based heterojunction nanocomposite material; the soluble metal salt comprises a soluble salt of copper or nickel. In the present invention, the two-dimensional Co3O4 nanosheets are obtained by pyrolytic oxidation of the ZIF-67 nanosheets, enabling the cobalt-based heterojunction nanocomposite material to inherit the advantages of the large specific surface area of ​​the ZIF-67 nanosheets; in the present invention, the two-dimensional Co3O4 nanosheets are mixed with a cationic surfactant, water, a soluble metal salt, and a borohydride salt, and performing a reduction reaction. Under the action of the borohydride salt, the soluble metal salt is successfully reduced, and the metal interacts with the two-dimensional Co3O4 nanosheets to form a cobalt-based heterojunction nanocomposite material. The present invention obtains a cobalt-based heterojunction nanocomposite material by adopting a method of pyrolysis oxidation treatment assisted by borohydride salt reduction. The composite material uses two-dimensional Co3O4 nanosheets as a carrier and inherits the advantage of large specific surface area of ​​ZIF-67 nanosheets. At the same time, the metal cation and oxygen anion defects in the cobalt-based heterojunction nanocomposite material make the cobalt-based heterojunction nanocomposite material have abundant active sites, which provides a great advantage for electron transfer and small molecule adsorption. At the same time, the formation of the heterojunction interface can further improve the conductivity of the cobalt-based heterojunction nanocomposite material. It is used as a modified material to prepare a working electrode for photoelectrochemical detection of glucose, which exhibits excellent detection sensitivity and good photoelectric response. The results of the embodiment show that the cobalt-based heterojunction nanocomposite material obtained by the method of the present invention is used as a modified electrode material for photoelectrochemical detection of glucose, and the sensitivity can reach 12 to 14 mA·mM -1 cm -2 The detection limit is 0.01~0.05mM, the response time is 0.5~2.5s, and it has good photoelectric response and sensitivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 Schematic diagram of the microwave carbon bath used in Examples 1-2 and Comparative Example 1 of the present invention;

[0021] Figure 2 The Cu / Cu prepared in Example 1 of the present invention 2+1 XRD curve of O / Co3O4;

[0022] Figure 3 The Cu / Cu prepared in Example 1 of the present invention 2+1 SEM images of O / Co3O4 materials;

[0023] Figure 4The Cu / Cu prepared in Example 1 of the present invention 2+1 Current-time curve of O / Co3O4 material;

[0024] Figure 5 This is the current-time curve of the Ni / Co3O4 material prepared in Example 2 of the present invention;

[0025] Figure 6 This is the current-time curve of Co / Co3O4 prepared in Comparative Example 1 of the present invention;

[0026] Figure 7 The Cu / Cu prepared in Example 1 of the present invention 2+1 Photoelectrochemical detection curve of glucose by O / Co3O4 material;

[0027] Figure 8 The Cu / Cu prepared in Example 1 of the present invention 2+1 Photoresponse current-time curve of O / Co3O4 material. DETAILED DESCRIPTION

[0028] The present invention provides a method for preparing a cobalt-based heterojunction nanocomposite material, comprising the following steps:

[0029] The ZIF-67 nanosheets were pyrolyzed and oxidized to obtain two-dimensional Co3O4 nanosheets;

[0030] The two-dimensional Co3O4 nanosheets are mixed with a cationic surfactant, water, a soluble metal salt and a borohydride salt, and a reduction reaction is performed to obtain a cobalt-based heterojunction nanocomposite material; the soluble metal salt includes a soluble salt of copper or nickel.

[0031] The present invention performs pyrolysis and oxidation treatment on ZIF-67 nanosheets to obtain two-dimensional Co3O4 nanosheets.

[0032] The present invention does not particularly limit the source of the ZIF-67 nanosheets, and ZIF-67 nanosheets obtained by a preparation method well known to those skilled in the art can be used. In the present invention, the preparation method of the ZIF-67 nanosheets preferably includes the following steps:

[0033] (1) mixing a soluble cobalt salt, a template, and deionized water to obtain a solution A;

[0034] (2) mixing 2-methylimidazole and deionized water to obtain solution B;

[0035] (3) mixing the solution A obtained in step (1) with the solution B obtained in step (2), and performing a hydrothermal reaction to obtain ZIF-67 nanosheets.

[0036] There is no time sequence restriction for steps (1) and (2).

[0037] In the present invention, a soluble cobalt salt, a template and deionized water are preferably mixed to obtain solution A.

[0038] In the present invention, the soluble cobalt salt is preferably cobalt acetate or cobalt nitrate, more preferably cobalt acetate tetrahydrate or cobalt nitrate hexahydrate. The present invention provides a cobalt source for the cobalt-based heterojunction nanocomposite material by selecting the above-mentioned soluble cobalt salt.

[0039] In the present invention, the template is preferably hexadecyltrimethylammonium bromide. In the present invention, the template can provide a guiding effect, changing the growth rate of a specific crystal face of ZIF-67, thereby regulating the two-dimensional morphology of ZIF-67, so that ZIF-67 exhibits a nanosheet morphology.

[0040] In the present invention, the molar ratio of the soluble cobalt salt to the template is preferably (1-3):(0.16-4.74), more preferably (2-3):(0.2-3), and even more preferably (2-3):(1-2). In the present invention, when the molar ratio of the soluble cobalt salt to the template is within the above range, the raw materials can be fully reacted.

[0041] The present invention does not particularly limit the amount of deionized water used, as long as it can dissolve the soluble cobalt salt and the template. In the present invention, the ratio of the mass of the soluble cobalt salt to the volume of the deionized water is preferably (0.249-0.747) g: (25-55) mL, more preferably (0.3-0.5) g: (40-50) mL.

[0042] The present invention does not particularly limit the method for mixing the soluble cobalt salt, template, and deionized water. A mixing method familiar to those skilled in the art can be used to fully dissolve the above components to form a uniform solution. In the present invention, the soluble cobalt salt, template, and deionized water are preferably mixed under magnetic stirring. The present invention does not particularly limit the speed and time of the magnetic stirring, as long as the above components are fully dissolved to form a uniform solution. In the present invention, the soluble cobalt salt, template, and deionized water are preferably mixed at room temperature.

[0043] In the present invention, 2-methylimidazole and deionized water are preferably mixed to obtain solution B.

[0044] In the present invention, the 2-methylimidazole serves as an organic ligand. During a hydrothermal reaction, Co self-assembles with the nitrogen on the imidazole ring of the organic ligand in a tetracoordinate manner, forming ZIF-67 nanosheets under the action of a template. In the present invention, the molar ratio of the soluble cobalt salt to the 2-methylimidazole is preferably (1-3):(29.2-87.7), more preferably (2-3):(40-60). In the present invention, when the molar ratio of the soluble cobalt salt to the 2-methylimidazole is within the above range, the components can fully react.

[0045] The present invention has no particular limitation on the amount of deionized water in the solution B, as long as it can dissolve 2-methylimidazole. In the present invention, the ratio of the mass of 2-methylimidazole in the solution B to the volume of the deionized water is preferably (2.4-7.2) g: (10-20) mL, more preferably (3-5) g: (15-20) mL.

[0046] The present invention does not particularly limit the method for mixing the 2-methylimidazole and deionized water. A mixing method well known to those skilled in the art can be used to dissolve the 2-methylimidazole in the deionized water. In the present invention, the 2-methylimidazole and deionized water are preferably mixed under magnetic stirring. The present invention does not particularly limit the speed and time of the magnetic stirring, as long as the 2-methylimidazole is dissolved in the deionized water. In the present invention, the 2-methylimidazole and deionized water are preferably mixed at room temperature.

[0047] In the present invention, the time sequence of obtaining the solution A and obtaining the solution B is not particular.

[0048] After obtaining solution A and solution B, the present invention preferably mixes the solution A with the solution B and performs a hydrothermal reaction to obtain ZIF-67 nanosheets.

[0049] In the present invention, the method of mixing the solution A and the solution B is preferably to quickly pour the solution B into the solution A, and then stir at room temperature for 1 to 2 hours, preferably for 1.5 to 2 hours. In the present invention, the method of mixing the solution A and the solution B affects the size of the ZIF-67 nanosheets. When the above mixing method is adopted, it is beneficial to obtain ZIF-67 nanosheets with smaller sizes, thereby increasing the specific surface area of ​​the ZIF-67 nanosheets, which is more conducive to obtaining better electrochemical performance. In the present invention, when the solution A and the solution B are mixed using the above method, the sheet thickness of the ZIF-67 nanosheets is preferably 50 to 150 nm, and the sheet diameter of the ZIF-67 nanosheets is preferably 0.5 to 1.5 μm.

[0050] In the present invention, the hydrothermal reaction temperature is preferably 80-160°C, more preferably 100-120°C; the hydrothermal reaction holding time is preferably 6-24 hours, more preferably 10-20 hours. In the present invention, when the hydrothermal reaction temperature and time are within the above ranges, the components can be fully reacted to form two-dimensional ZIF-67 nanosheets of uniform size and thickness, which is more conducive to improving the electrochemical performance of the final cobalt-based heterojunction nanocomposite product.

[0051] The present invention does not specifically limit the apparatus for the hydrothermal reaction, and any hydrothermal reaction apparatus known to those skilled in the art can be used. In the present invention, the hydrothermal reaction apparatus is preferably an autoclave. The present invention does not specifically limit the volume of the autoclave, and the volume can be selected based on the amount of reagents.

[0052] After the hydrothermal reaction is complete, the present invention preferably filters the resulting system, washes the residue, and then dries it to obtain ZIF-67 nanosheets. The methods for filtering, washing, and drying the residue are not particularly limited and can be employed using methods well known to those skilled in the art. In the present invention, the reagents for washing the residue are preferably deionized water and ethanol; the drying temperature for the residue is preferably 60°C, and the drying time is preferably 12 hours.

[0053] The present invention can prepare two-dimensional ZIF-67 nanosheets with uniform size and uniform sheet thickness by adopting the above preparation method.

[0054] In the present invention, the pyrolysis oxidation is preferably a microwave carbon bath. The microwave power of the microwave carbon bath is preferably 560 to 800 W, more preferably 650 to 750 W; the time of the microwave carbon bath is preferably 10 to 40 minutes, more preferably 20 to 30 minutes. In the present invention, the ZIF-67 nanosheets are subjected to a microwave carbon bath to undergo a carbonization oxidation reaction. When the microwave power and treatment time of the microwave carbon bath are within the above ranges, ZIF-67 is successfully oxidized to Co3O4. For cobalt-based oxides, the photoelectrochemical detection of glucose relies on Co 2+ / Co 3+ When ZIF-67 is fully oxidized to Co3O4, the Co 2+ / Co 3+ The high content makes the prepared cobalt-based heterojunction nanocomposite material more conducive to further improving the sensitivity of the detection results when used for photoelectrochemical detection of glucose.

[0055] In the present invention, the buried depth of the microwave carbon bath is preferably -2.0 to +2.0 cm, more preferably -1.0 to +1.0 cm. In the present invention, for cobalt-based oxides, the photoelectrochemical detection of glucose relies on Co 2+ / Co 3+ When the burial depth of the microwave carbon bath is within the above range, the product formed contains Co 2+ / Co 3+ A higher content is more conducive to improving the sensitivity of the detection results when the prepared high-cobalt-based heterojunction nanocomposite material is used for photoelectrochemical detection of glucose.

[0056] The present invention has no particular limitation on the device of the microwave carbon bath. A microwave carbon bath device well known to those skilled in the art can be used as long as it can achieve the above parameter range. In an embodiment of the present invention, the microwave carbon bath device is preferably a microwave oven, such as Galanz, R6-G238N3 (S0), 800W, 2.45GHz. In one embodiment of the present invention, the microwave carbon bath device is preferably as follows: Figure 1 shown.

[0057] After obtaining the two-dimensional Co3O4 nanosheets, the present invention mixes the two-dimensional Co3O4 nanosheets with a cationic surfactant, deionized water, a soluble metal salt and a borohydride salt, and performs a reduction reaction to obtain a cobalt-based heterojunction nanocomposite material.

[0058] In the present invention, the soluble metal salt includes a soluble salt of copper or nickel. In the present invention, when the soluble metal salt is of the aforementioned type, it can form a cobalt-based heterojunction nanocomposite material after a reduction reaction, which can ensure excellent sensitivity in the detection results when used for photoelectrochemical detection of glucose. In the present invention, the soluble copper salt is preferably CuCl2, and the soluble nickel salt is preferably NiCl2.

[0059] In the present invention, the cationic surfactant is preferably cetyltrimethylammonium bromide. In the present invention, when the cationic surfactant is cetyltrimethylammonium bromide, the molar ratio of cobalt ions in the two-dimensional Co3O4 nanosheets to the cetyltrimethylammonium bromide is preferably 1:0.01 to 0.05, more preferably 1:0.0345. The cationic surfactant of the present invention imparts a positive charge to the Co3O4 surface, enabling more uniform dispersion through electrostatic repulsion. When the molar ratio of cobalt ions in the two-dimensional Co3O4 nanosheets to the cetyltrimethylammonium bromide is within the above range, the two-dimensional Co3O4 nanosheets can be more evenly dispersed.

[0060] In the present invention, the borohydride salt is used as a reducing agent. When the soluble metal salt is a soluble salt of copper, due to the limited reducing ability of the borohydride salt, the relatively inert copper ions can be partially reduced to copper elemental substance, and the other part can be reduced to Cu 2+1 O; When the soluble metal salt is a soluble salt of nickel, the borohydride salt can reduce the nickel ions to nickel element due to the greater activity of nickel. 2+1 O and Co3O4 form a heterostructure, and nickel and Co3O4 form a heterostructure, so that the cobalt-based heterojunction nanocomposite material has abundant active sites. In the present invention, the borohydride salt preferably includes sodium borohydride or potassium borohydride.

[0061] In the present invention, the molar ratio of the cobalt ions in the two-dimensional Co3O4 nanosheets, the metal ions in the soluble metal salt, and the borohydride ions in the borohydride salt is preferably (0.2-1):1:(5-20), and more preferably (0.2-0.5):1:(10-15). In the present invention, when the molar ratio of the cobalt ions in the two-dimensional Co3O4 nanosheets, the metal ions in the soluble metal salt, and the borohydride ions in the borohydride salt is within the above range, the soluble metal salt can be reduced, and the metal and the two-dimensional Co3O4 nanosheets form a cobalt-based heterojunction nanocomposite material.

[0062] The amount of deionized water used in the present invention is not particularly limited, as long as it can evenly disperse the two-dimensional Co3O4 nanosheets, hexadecyltrimethylammonium bromide, soluble metal salt, and sodium borohydride. In the present invention, the ratio of the mass of the two-dimensional Co3O4 nanosheets to the volume of the deionized water is preferably (0.05-0.2) g: (20-100) mL, more preferably 0.1 g: 50 mL.

[0063] The present invention has no particular limitation on the method of mixing the two-dimensional Co3O4 nanosheets with the cationic surfactant, deionized water, soluble metal salt and sodium borohydride. A mixing method well known to those skilled in the art can be used to form a uniform mixed solution of the above components.

[0064] In the present invention, the reduction reaction temperature is preferably 25 to 75°C, more preferably 25 to 50°C; the reduction reaction time is preferably 0.5 to 2 hours, more preferably 1 hour. In the present invention, when the reduction reaction temperature and time are within the above ranges, the soluble metal salt can be reduced and a cobalt-based heterojunction nanocomposite material can be formed.

[0065] After the reduction reaction is complete, the present invention preferably sequentially filters the resulting system, washes the filter residue, and dries it to obtain a cobalt-based heterojunction nanocomposite material. The present invention does not specifically limit the methods for filtering, washing, and drying the filter residue; methods familiar to those skilled in the art can be employed. In the present invention, the reagents for washing the filter residue are preferably anhydrous ethanol and deionized water; the temperature for drying the filter residue is preferably 60°C, and the drying time is preferably 12 hours.

[0066] The present invention obtains a cobalt-based heterojunction by adopting a method of pyrolysis oxidation assisted borohydride salt reduction, inheriting the advantage of large specific surface area of ​​ZIF-67 nanosheets. At the same time, the metal cation and oxygen anion defects in the cobalt-based heterojunction nanocomposite material make the cobalt-based heterojunction nanocomposite material have abundant active sites, providing great advantages for electron transfer and small molecule adsorption; at the same time, the formation of the heterojunction interface further improves the conductivity of the cobalt-based heterojunction nanocomposite material, and it is used as a modified electrode material for photoelectrochemical detection of glucose, showing excellent detection sensitivity and good photoelectric response.

[0067] The present invention also provides a cobalt-based heterojunction nanocomposite material prepared by the preparation method of the above technical solution, comprising a two-dimensional porous nanosheet and nanoparticles loaded on the two-dimensional porous nanosheet, wherein the two-dimensional porous nanosheet is a two-dimensional Co3O4 nanosheet, and the nanoparticles include nickel particles or Cu and Cu 2+1 In the present invention, the loading amount of the nanoparticles on 1 g of the two-dimensional porous nanosheet is preferably 0.1 to 0.5 g, that is, the loading amount of the nanoparticles on the two-dimensional porous nanosheet is preferably 0.1 to 0.5 g / g.

[0068] In the present invention, the particle size of the nanoparticles is preferably 50 to 300 nm, more preferably 100 to 200 nm; the thickness of the two-dimensional porous nanosheets is preferably 20 to 100 nm, more preferably 50 to 80 nm. The cobalt-based heterojunction nanocomposite provided by the present invention has a particle size and sheet thickness within the above ranges, is nanoscale, and has a large specific surface area. This enables the cobalt-based heterojunction nanocomposite to have abundant active sites, providing significant advantages for electron transfer and small molecule adsorption. Using the cobalt-based heterojunction nanocomposite as a modifying material for a working electrode is more conducive to improving the sensitivity of the detection results when used for photoelectrochemical detection of glucose.

[0069] In the present invention, the cobalt-based heterojunction nanocomposite material preferably comprises Cu / Cu 2+1The cobalt-based heterojunction nanocomposite material provided by the present invention has the aforementioned crystalline structure. The heterojunction formed by the metal and Co3O4 has abundant active sites, providing significant advantages for electron transfer and small molecule adsorption. Furthermore, the formation of the heterojunction interface further enhances the conductivity of the cobalt-based heterojunction nanocomposite material, making it a suitable material for modifying the working electrode in photoelectrochemical glucose detection, which is more conducive to improving the sensitivity of the detection results.

[0070] The present invention also provides a working electrode, which includes a substrate and a modifying material coated on the substrate, wherein the modifying material includes the cobalt-based heterojunction nanocomposite material described in the above technical solution.

[0071] In the present invention, the substrate is preferably nickel foam. The present invention has no particular limitation on the size of the nickel foam, which can be adjusted as needed. In the present invention, the size of the nickel foam is preferably 1*1.5 cm.

[0072] In the present invention, the modified material comprises the cobalt-based heterojunction nanocomposite material described in the above technical solution. In the present invention, the thickness of the modified material on the substrate is preferably 0.5 to 2 mm.

[0073] The present invention has no particular limitation on the preparation method of the working electrode. A preparation method of the working electrode well known to those skilled in the art may be used as long as the modified material on the substrate falls within the above range.

[0074] In the present invention, the working electrode is preferably prepared by mixing a cobalt-based heterojunction nanocomposite material, a binder and a solvent to obtain a mixed slurry, coating the mixed slurry on nickel foam, and drying to obtain a working electrode.

[0075] In the present invention, the cobalt-based heterojunction nanocomposite material, a binder and a solvent are preferably mixed to obtain a mixed slurry.

[0076] The present invention has no particular limitation on the type of the binder, and any binder known to those skilled in the art can be used. In the present invention, the binder is preferably polytetrafluoroethylene.

[0077] The present invention has no particular limitation on the solvent, as long as it can fully disperse the cobalt-based heterojunction nanocomposite material. In the present invention, the solvent is preferably a mixture of ethanol and water in a volume ratio of 1:1.

[0078] In the present invention, the concentration of the cobalt-based heterojunction nanocomposite material in the mixed slurry is preferably 2-7 mg / mL, more preferably 5 mg / mL.

[0079] The present invention does not specifically limit the amount of the binder used, and can be adjusted according to the concentration of the mixed slurry. In the present invention, when the concentration of the cobalt-based heterojunction nanocomposite material in the mixed slurry is 2 to 7 mg / mL, the ratio of the volume of the binder to the volume of the solvent is preferably 1:100.

[0080] The present invention does not specifically limit the method for mixing the cobalt-based heterojunction nanocomposite material, the binder, and the solvent. A mixing method well known to those skilled in the art can be used to uniformly mix the components. In the present invention, the cobalt-based heterojunction nanocomposite material, the binder, and the solvent are preferably mixed ultrasonically. The present invention does not specifically limit the power or duration of the ultrasound, as long as the components are uniformly distributed in a slurry.

[0081] After obtaining the mixed slurry, the present invention preferably coats the mixed slurry on nickel foam and, after drying, obtains a working electrode. The amount of the mixed slurry coated on the nickel foam of the present invention is not particularly limited and is adjusted according to the concentration of the mixed slurry to ensure that the thickness of the modified material on the substrate after drying is 0.2 to 2 mm.

[0082] The present invention has no special limitation on the coating operation method. Any coating method well known to those skilled in the art can be used as long as the mixed slurry can form a coating with uniform thickness on the nickel foam.

[0083] The present invention has no particular limitation on the drying temperature and time, as long as the solvent in the mixed slurry can be fully removed. In the present invention, the drying temperature is preferably 60° C., and the drying time is preferably 12 hours.

[0084] The present invention also provides the use of the working electrode described in the above technical solution in photoelectrochemical detection of glucose.

[0085] The present invention does not particularly limit the method for using the working electrode in photoelectrochemical detection of glucose, and can employ methods familiar to those skilled in the art for using the working electrode in photoelectrochemical detection of glucose. In the present invention, the method for using the working electrode in photoelectrochemical detection of glucose is preferably to use the working electrode to construct an electrochemical sensor.

[0086] In the present invention, the electrochemical sensor preferably includes a working electrode, an auxiliary electrode, a reference electrode and an electrolyte.

[0087] The auxiliary electrode, reference electrode, and electrolyte are not particularly limited in the present invention; any auxiliary electrode, reference electrode, and electrolyte known to those skilled in the art may be used. In the present invention, the auxiliary electrode is preferably a platinum wire; the reference electrode is preferably Ag / AgCl; and the electrolyte is preferably a 0.1M NaOH solution.

[0088] The present invention does not specifically limit the method for detecting glucose with the electrochemical sensor; any method for detecting glucose with an electrochemical sensor known to those skilled in the art may be employed. In the present invention, the electrochemical sensor preferably detects glucose in a range of 0.1 to 1 mM glucose, employing a time-current curve for testing. As the glucose concentration gradually increases from 0.1 mM to 1 mM, current density values ​​are obtained for each concentration gradient. A linear relationship is established between current density and glucose concentration, and the slope represents the detection sensitivity.

[0089] The cobalt-based heterojunction nanocomposite provided by the present invention inherits the advantage of large specific surface area of ​​ZIF-67 nanosheets and has metal cation and oxygen anion defects, so that the cobalt-based heterojunction nanocomposite has abundant active sites, which provides great advantages for electron transfer and small molecule adsorption; at the same time, the formation of the heterojunction interface further improves the conductivity of the cobalt-based heterojunction nanocomposite, and it can be used as a modified electrode material for photoelectrochemical detection of glucose, showing excellent detection sensitivity and good photoelectric response.

[0090] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0091] Example 1

[0092] A method for preparing a cobalt-based heterojunction nanocomposite material, comprising the following steps:

[0093] (1) 0.249 g (0.001 mol) of cobalt acetate tetrahydrate, 0.0576 g (0.00016 mol) of cetyltrimethylammonium bromide (hereinafter referred to as CTAB), and 25 mL of deionized water were magnetically stirred at room temperature to dissolve the cobalt acetate tetrahydrate and CTAB in the deionized water to obtain solution A; wherein the molar ratio of the soluble cobalt salt (cobalt acetate tetrahydrate) to the CTAB was 1:0.16;

[0094] (2) 2.4 g (0.029 mol) of 2-methylimidazole and 10 mL of deionized water were magnetically stirred at room temperature to dissolve the 2-methylimidazole in the deionized water to obtain a solution B; wherein the molar ratio of the cobalt acetate tetrahydrate in step (1) to the 2-methylimidazole in step (2) was 1:29;

[0095] (3) The solution B obtained in step (1) was quickly poured into the solution A obtained in step (2), stirred at room temperature for 1 hour, and then subjected to a hydrothermal reaction in a 50 mL autoclave at a temperature of 120° C. for 8 hours. After washing with deionized water and anhydrous ethanol, the solution was treated at 60° C. for 12 hours to obtain ZIF-67 nanosheets;

[0096] (4) treating the ZIF-67 nanosheets obtained in step (3) in a microwave oven (Galanz, R6-G238N3(S0), 800W, 2.45GHz) at a power of 640W for 25min, with a burial depth of +2.0cm, to obtain two-dimensional Co3O4 nanosheets;

[0097] (5) The two-dimensional Co3O4 nanosheets obtained in step (4) were mixed with CTAB, deionized water, CuCl2 and sodium borohydride, and reduced at 25°C for 1 hour. After washing with deionized water and anhydrous ethanol, the mixture was treated at 60°C for 12 hours to obtain a cobalt-based heterojunction nanocomposite material, referred to as Cu / Cu 2+1 O / Co3O4; wherein the amount of cobalt ions in the two-dimensional Co3O4 nanosheets and the amount of CTAB is 1:0.0345, the cobalt ions in the two-dimensional Co3O4 nanosheets, the Cu in CuCl2 2+ The molar ratio of borohydride ions in sodium borohydride is 1.2:1:5.

[0098] After testing, the cobalt / cobalt-based heterojunction composite material prepared in this embodiment has Cu and Cu 2+1 The loading amount of the nanoparticles formed by O on the two-dimensional porous nanosheets is 0.2 g / g, the particle size of the nanoparticles is 50 nm, and the thickness of the two-dimensional porous nanosheets is 50 nm.

[0099] The Cu / Cu prepared in Example 1 was analyzed by X-ray diffractometer. 2+1 O / Co3O4 was characterized and Cu / Cu was obtained 2+1 The X-ray diffraction curve of O / Co3O4 is as follows Figure 2 As shown. Figure 2 It can be seen that the cobalt-based heterojunction nanocomposite prepared in this embodiment includes Cu, Cu 2+1 O and Co3O4.

[0100] The Cu / Cu prepared in Example 1 was observed by scanning electron microscopy. 2+1 O / Co3O4 was characterized and Cu / Cu was obtained 2+1 The SEM image of O / Co3O4 is as follows Figure 3 As shown. Figure 3 Cu / Cu can be clearly observed 2+1 The O / Co3O4 structure is nanospheres attached to the surface of nanosheets.

[0101] Example 2

[0102] A method for preparing a cobalt-based heterojunction nanocomposite material, comprising the following steps:

[0103] (1) 0.747 g (0.003 mol) of cobalt acetate tetrahydrate, 1.728 g (0.00474 mol) of CTAB, and 55 mL of deionized water were magnetically stirred at room temperature to dissolve the cobalt acetate tetrahydrate and CTAB in the deionized water to obtain solution A; wherein the molar ratio of the soluble cobalt salt (cobalt acetate tetrahydrate) to the CTAB was 3:4.74;

[0104] (2) 7.2 g (0.0877 mol) of 2-methylimidazole and 20 mL of deionized water were magnetically stirred at room temperature to dissolve the 2-methylimidazole in the deionized water to obtain a solution B; wherein the molar ratio of the cobalt acetate tetrahydrate in step (1) to the 2-methylimidazole in step (2) was 3:87.7;

[0105] (3) quickly pouring the solution B obtained in step (1) into the solution A obtained in step (2), stirring at room temperature for 1 hour, and then performing a hydrothermal reaction in a 100 mL autoclave at a temperature of 160° C. for 16 hours. After washing with anhydrous ethanol and deionized water, the solution was treated at 60° C. for 12 hours to obtain ZIF-67 nanosheets;

[0106] (4) treating the ZIF-67 nanosheets obtained in step (3) in a microwave oven (Galanz, R6-G238N3(S0), 800W, 2.45GHz) at 800W power for 15min, with a burial depth of -2.0cm, to obtain two-dimensional Co3O4 nanosheets;

[0107] (5) The two-dimensional Co3O4 nanosheets obtained in step (4) are mixed with CTAB, deionized water, NiCl2 and sodium borohydride, and a reduction reaction is carried out at 50°C for 1 hour. After washing with anhydrous ethanol and deionized water, the mixture is treated at 60°C for 12 hours to obtain a cobalt-based heterojunction nanocomposite material, referred to as Ni / Co3O4; wherein the molar ratio of the cobalt ions in the two-dimensional Co3O4 nanosheets to the CTAB is 1:0.0345, and the cobalt ions in the two-dimensional Co3O4 nanosheets and the Ni in CuCl2 are 0. 2+ The molar ratio of borohydride ions in sodium borohydride is 1.2:1:10.

[0108] According to tests, in the cobalt / cobalt-based heterojunction composite material prepared in this embodiment, the loading amount of Ni nanoparticles on the two-dimensional porous nanosheets is 0.3 g / g, the particle size of the nanoparticles is 70 nm, and the thickness of the two-dimensional porous nanosheets is 60 nm.

[0109] Comparative Example 1

[0110] A method for preparing a cobalt / cobalt-based heterojunction composite material, comprising the following steps:

[0111] (1) 0.498 g (0.002 mol) of cobalt acetate tetrahydrate, 1.152 g (0.003 mol) of CTAB, and 40 mL of deionized water were magnetically stirred at room temperature to dissolve the cobalt acetate tetrahydrate and CTAB in the deionized water to obtain solution A; wherein the molar ratio of the soluble cobalt salt (cobalt acetate tetrahydrate) to the CTAB was 2:3;

[0112] (2) 4.8 g (0.058 mol) of 2-methylimidazole and 15 mL of deionized water were magnetically stirred at room temperature to dissolve the 2-methylimidazole in the deionized water to obtain a solution B; wherein the molar ratio of the cobalt acetate tetrahydrate in step (1) to the 2-methylimidazole in step (2) was 2:58;

[0113] (3) The solution B obtained in step (1) was quickly poured into the solution A obtained in step (2), stirred at room temperature for 1.5 hours, and then subjected to a hydrothermal reaction in a 100 mL autoclave at a temperature of 120° C. for 12 hours. After washing with anhydrous ethanol and deionized water, the solution was treated at 60° C. for 12 hours to obtain ZIF-67 nanosheets;

[0114] (4) treating the ZIF-67 nanosheets obtained in step (3) in a microwave oven (Galanz, R6-G238N3(S0), 800W, 2.45GHz) at a power of 720W for 20min, with a burial depth of 0cm, to obtain two-dimensional Co3O4 nanosheets;

[0115] (5) The two-dimensional Co3O4 nanosheets obtained in step (4) are mixed with CTAB, deionized water, CoCl2 and sodium borohydride, and reduced at 75°C for 1 hour. After washing with anhydrous ethanol and deionized water, the mixture is treated at 60°C for 12 hours to obtain a cobalt / cobalt-based heterojunction composite material, referred to as Co / Co3O4; wherein the molar ratio of the cobalt ions in the two-dimensional Co3O4 nanosheets to the CTAB is 1:0.0345, and the cobalt ions in the two-dimensional Co3O4 nanosheets and the Co in the CoCl2 are 0. 2+ The molar ratio of borohydride ions in sodium borohydride is 1.2:1:20.

[0116] According to tests, the loading amount of Co nanoparticles on the two-dimensional porous nanosheets in the cobalt / cobalt-based heterojunction composite material prepared in this embodiment is 0.5 g / g, the particle size of the nanoparticles is 90 nm, and the thickness of the two-dimensional porous nanosheets is 100 nm.

[0117] Application Example 1

[0118] 5 mg of the cobalt-based heterojunction nanocomposite material Cu / Cu obtained in Example 1 was added 2+1 Cu / CuO / Co3O4 was dispersed in a mixed solution of ethanol and water with a volume ratio of 1:1, and 10 μL of polytetrafluoroethylene (PTFE) was added as a binder. The mixed slurry was ultrasonicated for 30 min to obtain a mixed slurry. The concentration of the cobalt-based heterojunction nanocomposite material in the mixed slurry was 5 mg / mL. The mixed slurry was evenly spread on a 1*1.5 cm nickel foam (NF). The nickel foam was placed in a vacuum drying oven at 60 ° C for 12 h to obtain Cu / Cu 2+1 O / Co3O4 / NF, Cu / Cu after drying 2+1 The thickness of O / Co3O4 on NF is 0.5mm.

[0119] Cu / Cu 2+1 O / Co3O4 / NF was used as the working electrode, platinum wire as the auxiliary electrode, Ag / AgCl as the reference electrode, and 0.1 M NaOH solution as the electrolyte to form a three-electrode system. The Cu / Cu prepared in Example 1 was tested using a Shanghai Chenhua electrochemical workstation (CHI760E). 2+1 The current-time curve of O / Co3O4 material was tested, and the voltage window was set to 0.6V during the test to obtain Cu / Cu 2+1 The current-time curve of O / Co3O4 material is as follows Figure 4 As shown, the sensitivity can reach 12.567mA·mM -1 cm -2 This shows that the working electrode prepared in this example has excellent sensitivity.

[0120] A xenon lamp was used as the light source to irradiate the Cu / Cu prepared in Example 1. 2+1 O / Co3O4 was tested for current-time curve. During the test, the light intensity was adjusted to 100 mW·cm -2 Under this illumination condition, the three-electrode system was used to detect glucose in a 0.1M NaOH solution. As the glucose concentration increased, the current response increased. A linear relationship was drawn between the glucose concentration and the corresponding concentration response current value, and the slope was the sensitivity of glucose detection. 2+1 The photoelectrochemical detection curve of glucose by O / Co3O4 material is shown in Figure 4. Figure 7 shown.

[0121] A xenon lamp was used as the light source to irradiate the Cu / Cu prepared in Example 1. 2+1 O / Co3O4 was tested for current-time curve. During the test, the light intensity was adjusted to 100 mW·cm -2 , and obtain Cu / Cu 2+1 The photoresponse curve of O / Co3O4 is as follows Figure 8 As shown. Figure 7 and Figure 8 It can be seen that Cu / Cu 2+1 The sensitivity of O / Co3O4 to glucose under light is 13.430 mA·mM -1 cm -2 , compared with the no light condition, it increased by 0.863mA·mM -1 cm -2 , while Figure 8 Cu / Cu was tested in 2+1 The photoresponse performance of O / Co3O4 was studied. It was found that the current changed significantly during the switching process of the light source, indicating that it has excellent photoelectric response.

[0122] Application Example 2

[0123] 5 mg of the cobalt-based heterojunction nanocomposite material Ni / Co3O4 obtained in Example 2 was dispersed in a mixed solution of ethanol and water in a volume ratio of 1:1, 10 μL of PTFE was added as a binder, and ultrasonication was performed for 30 min to obtain a mixed slurry, which was evenly applied on a 1*1.5 cm NF. The NF was placed in a vacuum drying oven at 60°C and dried for 12 h to obtain Ni / Co3O4 / NF.

[0124] Ni / Co3O4 / NF was used as the working electrode, platinum wire as the auxiliary electrode, Ag / AgCl as the reference electrode, and 0.1M NaOH solution as the electrolyte to form a three-electrode system. The Ni / Co3O4 material prepared in Example 2 was tested for current-time curve using a Shanghai Chenhua electrochemical workstation (CHI760E). During the test, the voltage window was set to 0.6 V. The current-time curve of the Ni / Co3O4 material was obtained as shown in the figure. Figure 5 As shown, the sensitivity can reach 12.481mA·mM -1 cm -2 .

[0125] Comparative Application Examples

[0126] 5 mg of Co / Co3O4 obtained in Comparative Example 1 was dispersed in a mixed solution of ethanol and water in a volume ratio of 1:1. 10 μL of PTFE was added as a binder, and ultrasonication was performed for 30 min to obtain a mixed slurry. The mixed slurry was evenly applied on a 1*1.5 cm NF. The NF was placed in a vacuum drying oven at 60°C and dried for 12 h to obtain CO / Co3O4 / NF.

[0127] Co / Co3O4 / NF was used as the working electrode, platinum wire as the auxiliary electrode, Ag / AgCl as the reference electrode, and 0.1M NaOH solution as the electrolyte to form a three-electrode system. The Co / Co3O4 material prepared in Comparative Example 1 was tested for current-time curve using a Shanghai Chenhua electrochemical workstation (CHI760E). During the test, the voltage window was set to 0.6V, and the current-time curve of the Co / Co3O4 material was obtained as shown in the figure. Figure 6 As shown, after calculation, its sensitivity can reach 3.656mA·mM -1 cm -2 .

[0128] It can be seen from the above examples that the cobalt-based heterojunction nanocomposite material prepared by the present invention is used as a modified electrode material for photoelectrochemical detection of glucose, and has excellent photoelectric response and sensitivity, which proves that the cobalt-based heterojunction nanocomposite material has good application prospects as an electrode material for detecting glucose.

[0129] 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. A method for preparing a cobalt-based heterojunction nanocomposite material, comprising the following steps: The ZIF-67 nanosheets were pyrolyzed and oxidized to obtain two-dimensional Co3O4 nanosheets; The two-dimensional Co3O4 nanosheets are mixed with a cationic surfactant, water, a soluble metal salt and a borohydride salt, and subjected to a reduction reaction to obtain a cobalt-based heterojunction nanocomposite material; the soluble metal salt includes a soluble salt of copper or nickel; The molar ratio of the cobalt ions in the two-dimensional Co3O4 nanosheets, the metal ions in the soluble metal salt, and the borohydride ions in the borohydride salt is (0.2-1):1:(5-20); The two-dimensional Co3O4 nanosheet is a two-dimensional porous nanosheet; the cobalt-based heterojunction nanocomposite material comprises a two-dimensional porous nanosheet and nanoparticles loaded on the two-dimensional porous nanosheet, wherein the nanoparticles comprise nickel particles or a combination of Cu and Cu 2+1 O particles formed.

2. The preparation method according to claim 1, characterized in that The pyrolysis oxidation treatment is a microwave carbon bath.

3. The preparation method according to claim 2, characterized in that The microwave power of the microwave carbon bath is 560-800W; and the time of the microwave carbon bath is 10-40 minutes.

4. The preparation method according to claim 1, characterized in that The borohydride salt includes sodium borohydride or potassium borohydride.

5. The cobalt-based heterojunction nanocomposite material prepared by the preparation method according to any one of claims 1 to 4, comprising a two-dimensional porous nanosheet and nanoparticles supported on the two-dimensional porous nanosheet, wherein the two-dimensional porous nanosheet is a two-dimensional Co3O4 nanosheet, and the nanoparticles include nickel particles or Cu and Cu 2+1 O particles formed.

6. The cobalt-based heterojunction nanocomposite material according to claim 5, characterized in that: The thickness of the two-dimensional porous nanosheet is 20-100 nm.

7. The cobalt-based heterojunction nanocomposite material according to claim 5, characterized in that: The particle size of the nanoparticles is 50 to 300 nm.

8. A working electrode comprising a substrate and a modifying material coated on the substrate, wherein the modifying material comprises the cobalt-based heterojunction nanocomposite material according to any one of claims 5 to 7.

9. Use of the working electrode according to claim 8 in photoelectrochemical detection of glucose.

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