Zeolite-like imidazolate framework compound, and preparation method and application thereof

Abstract

The application discloses a zeolite-like imidazolate framework compound and a preparation method and application thereof. The preparation method of the zeolite-like imidazolate framework compound comprises the following steps: S1, using a conductive substrate as a working electrode and forming a standard three-electrode system with a reference electrode and a counter electrode, using a metal ion solution and a nitrogen-containing organic ligand solution as electrolyte solutions, and constructing a reactor; S2, synthesizing the zeolite-like imidazolate framework compound on the conductive substrate in S1 through an electrochemical method; wherein, the solvent of the metal ion solution and the nitrogen-containing organic ligand solution in S1 is water or a mixed solution of water and a weak polar solvent, and the weak polar solvent is at least one of methanol, acetonitrile and acetone. By using the three-electrode system and the aqueous electrolyte solution to jointly act, the zeolite-like imidazolate framework compound with specific morphology can be efficiently synthesized under mild conditions, and when the zeolite-like imidazolate framework compound is applied to the detection of uric acid, the zeolite-like imidazolate framework compound has good response to uric acid.

Description

Technical Field

[0001] This invention relates to the field of metal-organic framework materials technology, and more specifically, to a zeolite-like imidazole ester framework compound, its preparation method, and its application. Background Technology

[0002] Zeolitic imidazolate frameworks (ZIFs) are compounds with cobalt ions (Co) 2+ ) or zinc ions (Zn 2+ ZIFs are a series of long-range ordered metal-organic frameworks with zeolite-like structures, formed through coordination interactions using zinc ions (Zn0.05) as nodes and nitrogen-containing organic ligands as linkers. The two most representative ZIFs are compounds formed by zinc ions (Zn0.05) as nodes and nitrogen-containing organic ligands as linkers. 2+ ZIFs-8 formed by ) and 2-methylimidazole, and by cobalt ions (Co 2+ ZIFs-67 are formed from 2-methylimidazole and 2-methylimidazole. With abundant metal ions and a wide variety of nitrogen-containing organic ligands, the coordination directions and connection modes are highly diverse, making ZIFs a special class of materials attracting considerable attention. ZIFs materials exhibit rich morphologies, diverse structures, tunable internal channels, and controllable pore sizes. They possess robust structures, large specific surface areas, unique physical properties, and are easily functionalized, showing very promising application prospects in mixture separation, catalytic synthesis, energy conversion, and target carrier delivery.

[0003] ZIFs (zinc-based inert materials) are primarily powders, prepared using methods such as solvothermal methods, solution mixing, and microwave dispersion. ZIF powders are highly suitable for target delivery and hold great potential in pharmaceutical fields such as in vivo imaging and drug delivery. However, for industrial-scale separation, catalysis, and conversion processes, ZIF powders are difficult to apply on a large scale. A common solution is to use crosslinking agents or substrates to form ZIF powders into films or blocks. Plasticity and processability are key technologies for realizing the large-scale industrial application of ZIF materials.

[0004] Currently, the main methods for loading ZIF powders onto substrate materials to form bulk structures include coating, immersion, solvothermal, and electrochemical methods. Coating involves applying ZIFs to the carrier surface using additives or binders to form a ZIF modification layer. However, the use of additives or binders can cover the ZIFs, thus affecting their performance. Immersion involves immersing the substrate material in a ZIF solution, achieving ZIF deposition on the substrate surface through prolonged and repeated immersion. While convenient, immersion is time-consuming, and the substrate's front and back surfaces are susceptible to deposition factors, leading to uneven ZIF deposition. The solvothermal method places the substrate material in a high-pressure reactor, vaporizing the solvent at high temperature, followed by cooling to allow ZIFs to crystallize and precipitate on the substrate surface. The solvothermal method can achieve in-situ growth of various ZIFs on substrate materials. However, the solvothermal method is cumbersome, requiring high temperature and pressure conditions, and the entire process carries the risk of explosion.

[0005] Electrochemical methods include current-controlled and potential-controlled methods. Current-controlled methods involve applying an oxidation current to induce metal ions in the metal substrate. These ions rapidly combine with nitrogen-containing organic ligands in solution to form a ZIF (zinc-insoluble iron-phosphate) modified layer covering the substrate surface. This method requires high-intensity current, resulting in high energy consumption and a risk of electric shock. Potential-controlled methods require applying a very high potential to a conductive substrate, and the preparation process must be carried out in organic solvents such as methanol, ethanol, and acetone, presenting numerous potential risks.

[0006] For example, existing technologies disclose a method for the rapid preparation of structure-controllable metal-organic framework compounds using electrochemical methods. This method electrosynthesizes metal-organic framework materials on a conductive substrate, but the resulting metal-organic framework material is a layered thin film, which cannot be used to prepare micro / nano-structured metal-organic framework materials. Furthermore, this method requires a high voltage of -5.0V in flammable and explosive methanol, posing a high risk to the synthesis conditions and hindering large-scale practical application. Summary of the Invention

[0007] The purpose of this invention is to overcome the defects and shortcomings of existing methods for preparing metal-organic framework materials, such as flammable and explosive synthesis media and complex and cumbersome synthesis processes. This invention provides a method for preparing zeolite-like imidazole ester framework compounds. A conductive substrate is used as the working electrode to form a standard three-electrode system with a reference electrode and a counter electrode. At the same time, an aqueous electrolyte solution is used to construct a reactor. The three-electrode system and the aqueous electrolyte solution work together to rapidly synthesize ZIFs with specific morphologies under mild conditions.

[0008] Another object of the present invention is to provide a zeolite-like imidazole ester skeleton compound prepared by the above-described preparation method.

[0009] Another object of the present invention is to provide the application of the above-mentioned zeolite-like imidazole ester skeleton compounds in catalysis, separation or energy conversion.

[0010] The above-mentioned objective of this invention is achieved through the following technical solution:

[0011] A method for preparing a zeolite-like imidazole ester skeleton compound includes the following steps:

[0012] S1. A reactor is constructed using a conductive substrate as the working electrode and forming a standard three-electrode system with a reference electrode and a counter electrode, and using a metal ion solution and a nitrogen-containing organic ligand solution as the electrolyte solution.

[0013] S2: A zeolite-like imidazole ester framework compound was synthesized on the conductive substrate described in S1 by an electrochemical method;

[0014] Wherein, the solvent for the metal ion solution and the nitrogen-containing organic ligand solution in S1 is water or a mixture of water and a weakly polar solvent, wherein the weakly polar solvent is at least one of methanol, acetonitrile and acetone.

[0015] This invention constructs a reactor for ZIFs by combining an aqueous electrolyte solution with a three-electrode system. By adjusting the potential or current parameters of the working electrode (conductive substrate), the enrichment of metal ions on the surface of the conductive substrate is improved and promoted. This allows nitrogen-containing organic ligands and metal ions to rapidly and efficiently form special saber-shaped or flower-shaped ZIFs on the surface of the conductive substrate, thereby greatly improving the electrocatalytic performance of uric acid molecules. Furthermore, it can be used to construct an electrochemical sensor for detecting uric acid with low detection limit, wide detection range, and high sensitivity.

[0016] Preferably, the concentration of metal ions in the electrolyte solution of S1 is 0.005–0.5 mol / L. More preferably, the concentration of metal ions in the electrolyte solution of S1 is 0.01–0.2 mol / L.

[0017] When the concentration of metal ions is 0.01–0.2 mol / L, special saber-shaped or flower-shaped ZIFs can be formed more efficiently on conductive substrates.

[0018] Preferably, the molar ratio of metal ions to nitrogen-containing organic ligands in the electrolyte solution of S1 is 1:(4-200). More preferably, the molar ratio of metal ions to nitrogen-containing organic ligands in the electrolyte solution of S1 is 1:(8-160). Specifically, it can be 1:(8-16), 1:(16-160), 1:8, 1:16, or 1:160.

[0019] Preferably, the volume ratio of water to weakly polar solvent in the mixed solution of water and weakly polar solvent is (1-10):(10-1); more preferably, the volume ratio of water to weakly polar solvent in the mixed solution of water and weakly polar solvent is (1-4):1.

[0020] Research has shown that when there is more water in the mixed solution of water and weakly polar solvent, it is more conducive to the rapid accumulation of metal ions on the surface of conductive substrates and the formation of ZIFs with specific morphologies with nitrogen-containing organic ligands.

[0021] In a specific embodiment, the electrochemical method described in S2 has a potential of -1.0 to 0.2 V and a current density of 0.005 to 0.1 mA / cm². 2 Preferably, the electrochemical method described in S2 has a potential of -0.6 to -0.2 V and a current density of 0.01 to 0.05 mA / cm². 2 .

[0022] Preferably, the synthesis time in step S2 is 600–7200 s, and the temperature is 5–50 °C. More preferably, the synthesis time in step S2 is 2400–3600 s, and the temperature is 20–30 °C.

[0023] Specifically, the conductive substrate is any one of carbon cloth, mesh glassy carbon, nickel foam, and stainless steel mesh.

[0024] Specifically, the metal ion in S1 is a cobalt ion and / or a zinc ion; the nitrogen-containing organic ligand is one or more of imidazole, 2-methylimidazolium, 2-ethylimidazolium, imidazole-2-carboxaldehyde, and 3-methyl-1,2,4-triazole.

[0025] Preferably, the nitrogen-containing organic ligand is one or more of imidazole, 2-methylimidazolium, and 2-ethylimidazolium.

[0026] This invention also protects a zeolite-like imidazole ester skeleton compound prepared by the above-described method.

[0027] The application of the above-mentioned zeolite-like imidazole ester skeleton compound in sensing, catalysis, separation or energy conversion is also within the scope of protection of this invention.

[0028] Specifically, the application of the aforementioned zeolite-like imidazole ester skeleton compounds in electrochemical sensors for detecting uric acid.

[0029] Compared with the prior art, the present invention has the following beneficial technical effects:

[0030] This invention discloses a method for preparing zeolite-like imidazolium ester framework compounds. A conductive substrate is used as the working electrode, forming a standard three-electrode system with a reference electrode and a counter electrode. A reactor is constructed using an aqueous electrolyte solution. The three-electrode system and the aqueous electrolyte solution work together to efficiently synthesize zeolite-like imidazolium ester framework compounds with specific morphologies under mild conditions. When these zeolite-like imidazolium ester framework compounds are applied to uric acid detection, they exhibit high electrocatalytic activity for uric acid. When applied to the constructed electrochemical sensor, they demonstrate superior performance with low detection limits, wide detection range, and high sensitivity. Attached Figure Description

[0031] Figure 1 This is the current-time curve in step S2 of Example 1.

[0032] Figure 2 The images shown are scanning electron microscope (SEM) images (A) and elemental imaging images (B) of ZIFs-8 in Example 1.

[0033] Figure 3 The images shown are transmission electron microscopy (TEM) image (A) and elemental energy spectrum (EDS) of ZIFs-8 in Example 1.

[0034] Figure 4 The image shows the X-ray photoelectron spectrum of ZIFs-8 in Example 1.

[0035] Figure 5 The image shows the X-ray diffraction pattern of ZIFs-8 in Example 1.

[0036] Figure 6 This is the current-time curve in step S2 of Example 2.

[0037] Figure 7 The images shown are scanning electron microscope (SEM) images (A) and elemental imaging images (B) of ZIFs-67 in Example 2.

[0038] Figure 8 The images shown are transmission electron microscopy (TEM) images (A) and elemental energy dispersive spectroscopy (EDS) images (B) of ZIFs-67 in Example 2.

[0039] Figure 9 The image shows the X-ray photoelectron spectrum of ZIFs-67 in Example 2.

[0040] Figure 10 The image shows the X-ray diffraction pattern of ZIFs-67 in Example 2.

[0041] Figure 11 The potential-time curve is shown in step S2 of Example 3.

[0042] Figure 12 The image shows a scanning electron microscope (SEM) image (A) and an elemental energy dispersive spectroscopy (EDS) analysis result of ZIFs-67 in Example 3.

[0043] Figure 13 This is the current-time curve in step S2 of Example 4.

[0044] Figure 14 The image shows a scanning electron microscope (SEM) image (A) and an elemental energy dispersive spectroscopy (EDS) analysis result of ZIFs-67 in Example 4.

[0045] Figure 15 This is the current-time curve in step S2 of Example 5.

[0046] Figure 16 The image shows a scanning electron microscope (SEM) image (A) and an elemental energy dispersive spectroscopy (EDS) analysis result of ZIFs-8 in Example 5.

[0047] Figure 17 This is the current-time curve in step S2 of Example 6.

[0048] Figure 18 The image shows the scanning electron microscope (SEM) image (A) and the elemental energy dispersive spectroscopy (EDS) results (B) of Zn+Co-ZIFs in Example 6.

[0049] Figure 19 This is a scanning electron microscope image of ZIFs-8 in Example 7.

[0050] Figure 20 This is a scanning electron microscope image of ZIFs-8 in Example 8.

[0051] Figure 21 This is a scanning electron microscope image of ZIFs-67 in Example 9.

[0052] Figure 22 This is a scanning electron microscope image of ZIFs-14 in Example 10.

[0053] Figure 23 The image shows a scanning electron microscope (SEM) image of ZIFs-8 in Comparative Example 1.

[0054] Figure 24 Cyclic voltammetry diagrams of the response of ZIFs-8 and blank carbon cloth to uric acid in Example 1.

[0055] Figure 25 This is a differential pulse voltammogram of ZIFs-8 for detecting uric acid at different concentrations in Example 1. Detailed Implementation

[0056] The present invention will be further described below with reference to specific embodiments, but the embodiments do not limit the present invention in any way. Unless otherwise stated, the raw materials and reagents used in the embodiments of the present invention are conventionally purchased raw materials and reagents.

[0057] Example 1

[0058] A method for preparing ZIFs includes the following steps:

[0059] S1. A standard three-electrode system is formed using carbon cloth as the working electrode, a silver / silver chloride electrode (reference electrode), and a platinum wire (counter electrode), with zinc ions (Zn) as the working electrode. 2+ The reactor was constructed using zinc ion solution and 2-methylimidazole solution as electrolyte solutions; both zinc ion solution and 2-methylimidazole solution were prepared with water, with the concentration of zinc ion solution being 0.05 mol / L and 2-methylimidazole solution being 0.4 mol / L.

[0060] S2: First, add the above zinc ion solution to the reactor, and then use the controlled potential-current-time curve method (e.g.) Figure 1 As shown in the figure, with a silver / silver chloride electrode as a reference, the potential of the working electrode was controlled at -0.4V. After operation, an equal amount of 2-methylimidazole solution was added at a volume ratio of 1:1, and the reaction was carried out at 20℃ for 3600s to obtain the zeolite-like imidazole ester skeleton compound (ZIFs-8).

[0061] Figure 2 The images show scanning electron microscope (SEM) and elemental imaging of ZIFs-8 prepared in Example 1. The results show that when the electrolyte solution is water, the ZIFs-8 synthesized on the conductive carbon cloth substrate is leaf-shaped, and the main constituent elements are carbon, nitrogen and zinc. Figure 3 The images show transmission electron microscopy (TEM) images and elemental imaging of the ZIFs-8 prepared in Example 1. The results indicate that the ZIFs-8 prepared in Example 1 has a porous framework structure, and its main constituent elements are carbon, nitrogen, and zinc. Figure 4 The image shows the X-ray photoelectron spectrum of ZIFs-8 prepared in Example 1. Elemental energy dispersive spectroscopy analysis results show that the main constituent elements of the prepared ZIFs-8 are carbon, nitrogen and zinc, and the oxygen peak is oxygen adsorbed on the sample surface in the test environment. Figure 5 The image shows the X-ray diffraction pattern of ZIFs-8 obtained in Example 1. The X-ray diffraction analysis results indicate that the X-ray diffraction fingerprint peaks of the synthesized ZIFs-8 are consistent with those of the reported powdered L-ZIFs-8 in the literature. In summary, the above morphological, structural, and elemental composition analyses fully demonstrate that ZIFs can be synthesized on carbon cloth in an aqueous electrolyte solution using a potential-controlled method.

[0062] Example 2

[0063] A method for preparing ZIFs includes the following steps:

[0064] S1. A standard three-electrode system is formed using carbon cloth as the working electrode, a saturated calomel electrode (reference electrode), and a carbon rod (counter electrode), with cobalt ions (Co) as the working electrode. 2+The reactor was constructed using cobalt ion solution and 2-methylimidazole solution as electrolyte solutions; both cobalt ion solution and 2-methylimidazole solution were prepared with water, with the concentration of cobalt ion solution being 0.05 mol / L and the concentration of 2-methylimidazole solution being 0.8 mol / L.

[0065] S2: First, add the above cobalt ion solution to the reactor, and then use the controlled potential current-time curve method (e.g.) Figure 6 As shown in the figure, with a silver / silver chloride electrode as a reference, the potential of the working electrode was controlled at -0.5V. After operation, an equal amount of 2-methylimidazole solution was added at a volume ratio of 1:1, and the reaction was carried out at 25℃ for 3600s to obtain a zeolite-like imidazole ester skeleton compound (ZIFs-67).

[0066] Figure 7 The images show scanning electron microscope (SEM) images and elemental imaging diagrams of ZIFs-67 prepared in Example 2. The results show that when the electrolyte solution is water, the ZIFs-67 synthesized on the conductive carbon cloth substrate is sword-shaped, and the main constituent elements are carbon, nitrogen and cobalt. Figure 8 The images show transmission electron microscopy (TEM) images and elemental imaging of ZIFs-67 prepared in Example 2. The results show that the prepared ZIFs-67 is a non-solid porous framework structure, and its main constituent elements are carbon, nitrogen and cobalt. Figure 9 The image shows the X-ray photoelectron spectrum of ZIFs-67 prepared in Example 2. Elemental energy dispersive spectroscopy analysis results show that the main constituent elements of the prepared ZIFs-67 are carbon, nitrogen and cobalt, and the oxygen peak is oxygen adsorbed on the sample surface in the test environment. Figure 10 The image shows the X-ray diffraction pattern of ZIFs-67 obtained in Example 2. The X-ray diffraction analysis results indicate that the X-ray diffraction fingerprint peaks of the synthesized ZIFs-67 are consistent with the reported X-ray diffraction fingerprint peaks of powder L-ZIFs in the literature. In summary, the above morphological, structural, and elemental composition analyses fully demonstrate that ZIFs were successfully synthesized on carbon cloth in an aqueous electrolyte solution using a potential-controlled method.

[0067] Example 3

[0068] A method for preparing ZIFs includes the following steps:

[0069] S1. A standard three-electrode system is formed using carbon cloth as the working electrode, a silver / silver chloride electrode (reference electrode), and a platinum wire (counter electrode), with cobalt ions (Co) as the working electrode. 2+ The reactor was constructed using cobalt ion solution and 2-methylimidazole solution as electrolyte solutions; both cobalt ion solution and 2-methylimidazole solution were prepared with water, with the concentration of cobalt ion solution being 0.05 mol / L and the concentration of 2-methylimidazole solution being 0.8 mol / L.

[0070] S2: First, add the above cobalt ion solution to the reactor, and then use the chronopotential method (e.g., [unclear text - likely a typo]). Figure 11 As shown), with the assistance of a platinum wire counter electrode, the current density of the working electrode is controlled to be 0.02 mA / cm². 2 After running, an equal volume of 2-methylimidazole solution was added at a volume ratio of 1:1, and the reaction was carried out at 25°C for 3600 s to obtain the zeolite-like imidazole ester skeleton compound (ZIFs-67).

[0071] Figure 12 The images shown are scanning electron microscope (SEM) images (A) and elemental energy dispersive spectroscopy (EDS) results (B) of ZIFs-67 in Example 3. The results show that the ZIFs synthesized on carbon cloth using a controlled current method with pure aqueous solution are sword-shaped and mainly composed of carbon, nitrogen and cobalt. This fully demonstrates that ZIFs were successfully synthesized on carbon cloth using a controlled current method in an aqueous electrolyte solution.

[0072] Example 4

[0073] A method for preparing ZIFs includes the following steps:

[0074] S1. A standard three-electrode system is formed using nickel foam as the working electrode, a saturated calomel electrode (reference electrode), and a platinum wire (counter electrode), with cobalt ions (Co) as the working electrode. 2+ The reactor was constructed using cobalt ion solution and 2-methylimidazole solution as electrolyte solutions; both cobalt ion solution and 2-methylimidazole solution were prepared with water, with the concentration of cobalt ion solution being 0.05 mol / L and the concentration of 2-methylimidazole solution being 0.4 mol / L.

[0075] S2: First, add the above cobalt ion solution to the reactor, and then use the controlled potential current-time curve method (e.g.) Figure 13 As shown in the figure, using a saturated calomel electrode as a reference, the potential of the working electrode was controlled at -0.4V. After operation, an equal volume of 2-methylimidazole solution was added at a volume ratio of 1:1, and the reaction was carried out at 28℃ for 3600s to obtain a zeolite-like imidazole ester skeleton compound (ZIFs-67).

[0076] Figure 14 The images shown are the scanning electron microscope (SEM) image (A) and the elemental energy dispersive spectroscopy (EDS) analysis results of ZIFs-67 in Example 4. The above morphological and elemental composition analysis fully demonstrates that ZIFs can be successfully synthesized on nickel foam using pure aqueous solution via a potential-controlled method.

[0077] Example 5

[0078] A method for preparing ZIFs includes the following steps:

[0079] S1. A standard three-electrode system is formed using carbon cloth as the working electrode, a silver / silver chloride electrode (reference electrode), and a platinum wire (counter electrode), with zinc ions (Zn) as the working electrode. 2+A reactor was constructed using 2-methylimidazole solution and 2-methylimidazole solution as electrolytes; zinc ions (Zn) 2+ Both the zinc ion solution and the 2-methylimidazole solution were prepared using a water / methanol mixture (v / v = 4:1). The concentration of the zinc ion solution was 0.05 mol / L, and the concentration of the 2-methylimidazole solution was 0.4 mol / L.

[0080] S2: First, add the above zinc ion solution to the reactor, and then use the controlled potential-current-time curve method (e.g.) Figure 15 As shown in the figure, with a silver / silver chloride electrode as a reference, the potential of the working electrode was controlled at -0.3V. After operation, an equal amount of 2-methylimidazole solution was added at a volume ratio of 1:1, and the reaction was carried out at 30℃ for 2400s to obtain the zeolite-like imidazole ester skeleton compound (ZIFs-8).

[0081] Figure 16 The images shown are the scanning electron microscope (SEM) image (A) and elemental energy dispersive spectroscopy (EDS) results of ZIFs-8 in Example 5. The results show that ZIFs-8 synthesized on carbon cloth using a water and methanol solution via a current-controlled method is flower-shaped, and its main constituent elements are carbon, nitrogen, and zinc. The above morphological and elemental composition analysis fully demonstrates that ZIFs can be synthesized on carbon cloth using a water and methanol mixed solution via a potential-controlled method in Example 5.

[0082] Example 6

[0083] A method for preparing ZIFs includes the following steps:

[0084] S1. A standard three-electrode system was formed using carbon cloth as the working electrode, a silver / silver chloride electrode (reference electrode), and a titanium wire (counter electrode). A reactor was constructed using a mixed solution of metal ions and a 2-methylimidazole solution as the electrolyte solution. Both the mixed solution of metal ions and the 2-methylimidazole solution were prepared with water. The mixed solution of metal ions was a mixture of 0.025 mol / L zinc ions and 0.025 mol / L cobalt ions, and the 2-methylimidazole solution was 0.4 mol / L.

[0085] S2: First, add the above mixed metal ion solution to the reactor, and then use the controlled potential current-time curve method (e.g.) Figure 17 As shown, with a silver / silver chloride electrode as a reference, the potential of the working electrode was controlled at -0.4V. After operation, an equal amount of 2-methylimidazole solution was added at a volume ratio of 1:1, and the reaction was carried out at 30℃ for 3000s to obtain a zeolite-like imidazole ester skeleton compound (Zn+Co-ZIFs).

[0086] Figure 18The images shown are scanning electron microscope (SEM) images (A) and elemental energy dispersive spectroscopy (EDS) results (B) of the Zn+Co-ZIFs in the example. The results show that the Zn+Co-ZIFs containing zinc and cobalt synthesized on carbon cloth using a pure aqueous solution via a potential-controlled method are sword-shaped, and their main constituent elements are carbon, nitrogen, zinc and cobalt. The above morphological and elemental composition analysis fully demonstrates that ZIFs containing zinc and cobalt can be synthesized on carbon cloth using a pure aqueous solution via a potential-controlled method in Example 6.

[0087] Example 7

[0088] A method for preparing ZIFs includes the following steps:

[0089] S1. A standard three-electrode system is formed using carbon cloth as the working electrode, a silver / silver chloride electrode (reference electrode), and a platinum wire (counter electrode), with zinc ions (Zn) as the working electrode. 2+ The reactor was constructed using zinc ion solution and 2-methylimidazole solution as electrolyte solutions; both zinc ion solution and 2-methylimidazole solution were prepared using a water / methanol mixture (v / v = 1:1), with the concentration of zinc ion solution being 0.05 mol / L and 2-methylimidazole solution being 0.4 mol / L.

[0090] S2: First, add the above zinc ion solution to the reactor. Using the potential-current-time curve method with silver / silver chloride electrode as reference, control the potential of the working electrode to -0.4V. After running, add an equal amount of 2-methylimidazole solution at a volume ratio of 1:1. React at 20℃ for 3600s to obtain the zeolite-like imidazole ester skeleton compound (ZIFs-8).

[0091] Figure 19 The image shown is a scanning electron microscope image of ZIFs-8 in Example 7. The results indicate that ZIFs can also be synthesized on the surface of a conductive substrate when the solvent of the electrolyte solution is a mixture of water and methanol.

[0092] Example 8

[0093] A method for preparing ZIFs includes the following steps:

[0094] S1. A standard three-electrode system is formed using carbon cloth as the working electrode, a silver / silver chloride electrode (reference electrode), and a platinum wire (counter electrode), with zinc ions (Zn) as the working electrode. 2+ The reactor was constructed using zinc ion solution and 2-methylimidazole solution as electrolyte solutions; both zinc ion solution and 2-methylimidazole solution were prepared using a water / methanol mixture (v / v = 2:3), with the concentration of zinc ion solution being 0.05 mol / L and 2-methylimidazole solution being 0.4 mol / L.

[0095] S2: First, add the above zinc ion solution to the reactor. Using the potential-current-time curve method with silver / silver chloride electrode as reference, control the potential of the working electrode to -0.4V. After running, add an equal amount of 2-methylimidazole solution at a volume ratio of 1:1. React at 20℃ for 3600s to obtain the zeolite-like imidazole ester skeleton compound (ZIFs-8).

[0096] Figure 20 The image shown is a scanning electron microscope image of ZIFs-8 in Example 8. The results indicate that ZIFs can also be synthesized on the surface of a conductive substrate when the solvent of the electrolyte solution is a mixture of water and methanol.

[0097] Example 9

[0098] A method for preparing ZIFs includes the following steps:

[0099] S1. A standard three-electrode system is formed using carbon cloth as the working electrode, a silver / silver chloride electrode (reference electrode), and a platinum wire (counter electrode), with cobalt ions (Co) as the working electrode. 2+ The reactor was constructed using cobalt ion solution and 2-methylimidazole solution as electrolyte solutions; both cobalt ion solution and 2-methylimidazole solution were prepared with water, with the concentration of cobalt ion solution being 0.2 mol / L and the concentration of 2-methylimidazole solution being 1.6 mol / L.

[0100] S2: First, add the above cobalt ion solution to the reactor. Using the potential-current-time curve method with silver / silver chloride electrode as reference, control the potential of the working electrode to -0.2V. After running, add an equal amount of 2-methylimidazole solution at a volume ratio of 1:1 and react at 20℃ for 1800s to obtain the zeolite-like imidazole ester skeleton compound (ZIFs-67).

[0101] Figure 21 The image shows a scanning electron microscope (SEM) image of ZIFs-67 in Example 9. The results indicate that ZIFs can be synthesized on a conductive substrate when the concentration of the cobalt ion solution is 0.2 mol / L and the concentration of the 2-methylimidazole solution is 1.6 mol / L.

[0102] Example 10

[0103] A method for preparing ZIFs includes the following steps:

[0104] S1. A standard three-electrode system is formed using carbon cloth as the working electrode, a silver / silver chloride electrode (reference electrode), and a platinum wire (counter electrode), with zinc ions (Zn) as the working electrode. 2+ The reactor was constructed using zinc ion solution and 2-ethylimidazole solution as electrolyte solutions; both zinc ion solution and 2-ethylimidazole solution were prepared with water, with the concentration of zinc ion solution being 0.01 mol / L and 2-ethylimidazole solution being 1.6 mol / L.

[0105] S2: First, add the above zinc ion solution to the reactor. Using the potential-current-time curve method with silver / silver chloride electrode as reference, control the potential of the working electrode to -0.6V. After running, add an equal amount of 2-ethylimidazole solution at a volume ratio of 1:1 and react at 20℃ for 3600s to obtain the zeolite-like imidazole ester skeleton compound (ZIFs-14).

[0106] Figure 22 The image shows a scanning electron microscope (SEM) image of ZIFs-14 in Example 10. The results indicate that ZIFs can be synthesized on a conductive substrate when the concentration of the zinc ion solution is 0.01 mol / L and the concentration of the 2-ethylimidazole solution is 1.6 mol / L.

[0107] Comparative Example 1

[0108] A method for preparing ZIFs includes the following steps:

[0109] S1. A standard three-electrode system is formed using carbon cloth as the working electrode, a silver / silver chloride electrode (reference electrode), and a platinum wire (counter electrode), with zinc ions (Zn) as the working electrode. 2+ A reactor was constructed using zinc ion solution and 2-methylimidazole solution as electrolyte solutions; both zinc ion solution and 2-methylimidazole solution were prepared using methanol as solvent, with the concentration of zinc ion solution being 0.05 mol / L and 2-methylimidazole solution being 0.4 mol / L.

[0110] S2: First, add the above zinc ion solution to the reactor. Using the potential-current-time curve method with silver / silver chloride electrode as reference, control the potential of the working electrode to -0.4V. After running, add an equal amount of 2-methylimidazole solution at a volume ratio of 1:1. React at 20℃ for 3600s to obtain the zeolite-like imidazole ester skeleton compound (ZIFs-8).

[0111] Figure 23 The image shows a scanning electron microscope (SEM) image of ZIFs-8 in Comparative Example 1. The results indicate that when the solvent is the organic solvent methanol, saber-shaped ZIFs-8 cannot be obtained on the conductive substrate, and the growth effect is poor under low potential and short time conditions.

[0112] Performance testing

[0113] The conductive substrates with ZIFs attached to their surfaces in Examples 1-10 and Comparative Example 1 were used as working electrodes, forming a three-electrode system with a platinum electrode and a silver / silver chloride electrode. Cyclic voltammetry tests were performed on uric acid in phosphate buffer solution with a scan range of -0.2 to 0.6 V and a scan rate of 0.10 V / s. The control group was tested with blank carbon cloth as the working electrode.

[0114] The test results of carbon cloth / ZIFs-8 in Example 1 are as follows: Figure 24As shown, when the phosphate buffer solution does not contain uric acid, the response curves of carbon cloth / ZIFs-8 or blank carbon cloth are flat, with no current increase signal. However, after adding uric acid to the phosphate buffer solution, both carbon cloth / ZIFs-8 and blank carbon cloth respond to uric acid, and the current signal increases with increasing potential. Furthermore, it can be observed that, compared to blank carbon cloth, the current response of carbon cloth / ZIFs-8 to uric acid can rapidly increase at a lower potential, and the corresponding peak current density signal is significantly higher than that of blank carbon cloth (the peak current for uric acid response is 0.35 mA / cm²). 2 The peak potential of the uric acid response is 0.20V, which fully demonstrates that ZIFs-8 grown on carbon cloth (carbon cloth / ZIFs-8) has excellent electrocatalytic activity for the oxidation of uric acid, and can be used to construct a highly efficient electrochemical sensor for uric acid.

[0115] The carbon cloth / ZIFs in Examples 2-6 and Examples 9-10 showed basically the same response to uric acid as in Examples 7 and 8, and were superior to Comparative Example 1.

[0116] The conductive substrate with ZIFs attached to its surface, as described in Example 1, was used to construct an electrochemical sensor for uric acid detection. The carbon cloth / ZIFs-8 substrate from Example 1 was used as the working electrode, forming a three-electrode system with a platinum electrode and a silver / silver chloride electrode. Differential pulse voltammetry was performed under the following conditions: potential range: 0–0.5 V; pulse width: 0.06 s; sampling width: 0.02 s; pulse period: 0.5 s. Uric acid was gradually added to a blank phosphate buffer solution for differential pulse voltammetry testing. The results are as follows: Figure 25 As shown, the lowest uric acid response concentration is 0.01 μmol / L, and the linear range of the response is 0.01–100.0 μmol / L, demonstrating that the uric acid electrochemical sensor constructed with carbon cloth / ZIFs-8 has the performance advantages of low response concentration, wide linear range, and high sensitivity.

[0117] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. The application of a zeolite-like imidazole ester skeleton compound in an electrochemical sensor for detecting uric acid, characterized in that, The preparation method of the zeolite-like imidazole ester skeleton compound includes the following steps: S1. A reactor is constructed using a conductive substrate as the working electrode, forming a standard three-electrode system with a reference electrode and a counter electrode, and using a metal ion solution and a nitrogen-containing organic ligand solution as the electrolyte solution. S2: A zeolite-like imidazole ester framework compound was synthesized on the conductive substrate described in S1 by an electrochemical method; Wherein, the solvent for the metal ion solution and the nitrogen-containing organic ligand solution in S1 is water or a mixture of water and a weakly polar solvent, wherein the weakly polar solvent is at least one of methanol, acetonitrile and acetone; The concentration of metal ions in the electrolyte solution described in S1 is 0.01~0.2 mol / L; The electrochemical method described in S2 has a potential of -0.6 to -0.2 V and a current density of 0.01 to 0.05 mA / cm2; The metal ion in S1 is cobalt ion and / or zinc ion; the nitrogen-containing organic ligand is one or more of imidazole, 2-methylimidazolium, 2-ethylimidazolium, imidazole-2-carboxaldehyde and 3-methyl-1,2,4-triazole; and saber-shaped or flower-shaped ZIFs are formed on the conductive substrate.

2. The application as described in claim 1, characterized in that, The molar ratio of metal ions to nitrogen-containing organic ligands in the electrolyte solution described in S1 is 1:(4~200).

3. The application as described in claim 1, characterized in that, The volume ratio of water to weakly polar solvent in the mixed solution of water and weakly polar solvent is (1~10):(10~1).

4. The application as described in claim 1, characterized in that, The synthesis time described in S2 is 600~7200 s, and the temperature is 5~50 ℃.

5. The application as described in claim 1, characterized in that, The conductive substrate is any one of carbon cloth, mesh glassy carbon, nickel foam, and stainless steel mesh.

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