A tennis ball flower-shaped Cu@Mn / CNF-A and its preparation method and application

Abstract

The present invention relates to a tennis ball flower-shaped Cu@Mn / CNF‑A and a preparation method and application thereof, and belongs to the technical field of composite materials. The preparation method of the present invention comprises the following steps: using acidified carbon nanofiber CNF‑A as a substrate, in-situ growing a metal organic framework material ZIF‑8 on its surface and doping it with manganese, then in-situ growing a metal organic framework material HKUST‑1, and finally obtaining the tennis ball flower-shaped Cu@Mn / CNF‑A by carbonization treatment. Cu@Mn / CNF‑A has a large specific surface area, uniform distribution of manganese and copper elements, and many reactive sites, and its morphology is different from the polyhedral structure of traditional MOF but a tennis ball flower-shaped structure, which effectively increases the specific surface area of ​​the material, increases the reactive area, and greatly improves its electrocatalytic activity. The electrochemical sensor device constructed based on Cu@Mn / CNF‑A realizes highly sensitive and specific detection of H2O2 through the synergistic catalytic action of copper and manganese.

Description

Technical Field

[0001] The present invention belongs to the technical field of composite materials, and in particular relates to a tennis ball flower-shaped Cu@Mn / CNF-A and a preparation method and application thereof. Background Art

[0002] In recent years, metal-organic frameworks (MOFs) have been widely used in various fields due to their advantages, such as highly porous surfaces, excellent thermochemical stability, tunable structures, and multifunctionality. Although there are reports on the application of MOFs in nanoenzyme sensors, MOFs such as HKUST-1 typically have a polyhedral structure. During the sensing process, this makes it difficult for reactants to access the active sites, resulting in low utilization of the catalytic active sites and poor electrocatalytic performance of the sensor. Therefore, to improve the sensitivity of MOF-based sensors, it is very important to carefully design electrodes with more exposed reactive sites and a reasonable electronic structure. Hydrogen peroxide (H2O2) is an important signal-regulating molecule in cells. It has low concentrations, low content, and a short half-life. Both high and low molecular levels can cause pathological phenomena in cells. Achieving accurate and efficient detection of H2O2 is of great significance to human health. Therefore, developing a nano-biomimetic enzyme with multiple active sites based on MOFs is of great significance for constructing highly sensitive and selective H2O2 sensors and for the diagnosis and research of related diseases.

[0003] Traditional H2O2 sensors include enzyme sensors and biomimetic enzyme sensors. Enzyme sensors suffer from drawbacks such as poor reproducibility, short lifespan, high cost, susceptibility to inactivation, and stringent operating requirements, limiting their applicability. Biomimetic enzyme sensors, due to their low cost, high stability, simple preparation, and excellent catalytic activity, have become a research hotspot for electrochemical H2O2 detection. Currently, reported biomimetic enzyme sensors for H2O2 still suffer from high detection limits and low sensitivity for detecting small molecules in cells. Therefore, developing highly sensitive and selective H2O2 sensors is crucial for the diagnosis and research of major diseases.

[0004] Fundamentally, a surface electronic structure with a strong oxidized or reduced state greatly contributes to the oxidation or reduction kinetics of the electrode, respectively. In order to improve the sensitivity of the sensor, it is very important to carefully design electrodes with a reasonable electronic structure. Summary of the Invention

[0005] To this end, the technical problem to be solved by the present invention is to overcome the problems in the prior art of H2O2 sensors based on MOFs nano-bionic enzymes, such as low utilization of nano-enzyme reaction active sites, resulting in poor sensor performance and low sensitivity for detecting small molecules in cells.

[0006] In order to solve the above technical problems, the present invention provides a tennis ball flower-shaped Cu@Mn / CNF-A and its preparation method and application.

[0007] The first object of the present invention is to provide a method for preparing tennis flower-shaped Cu@Mn / CNF-A, comprising the following steps:

[0008] Using acidified carbon nanofiber CNF-A as the substrate, the metal organic framework material ZIF-8 was in situ grown on its surface and doped with manganese. Then the metal organic framework material HKUST-1 was in situ grown. Finally, the tennis ball flower-shaped Cu@Mn / CNF-A was obtained by carbonization treatment.

[0009] In one embodiment of the present invention, the preparation method specifically includes the following steps:

[0010] (1) adding acidified carbon nanofiber CNF-A to a mixed solution of zinc salt and manganese salt, mixing well, adding 2-methylimidazole, and reacting for 12 h to 36 h to obtain a reaction solution;

[0011] (2) dissolving copper salt and trimesic acid in N,N-dimethylformamide to obtain a copper salt concentration of 0.1M-0.5M and a copper ion to trimesic acid concentration ratio of 2:1-2:3, and then adding 50%-90% ethanol solution to obtain a mixed solution;

[0012] (3) adding the mixed solution described in step (2) to the reaction solution described in step (1), and after the reaction, centrifuging, washing, and drying to obtain HKUST-1 / Mn@ZIF-8 / CNF-A;

[0013] (4) Under a protective atmosphere, the HKUST-1 / Mn@ZIF-8 / CNF-A described in step (3) is carbonized to obtain the tennis ball-shaped Cu@Mn / CNF-A.

[0014] In one embodiment of the present invention, in step (1), the method for preparing the acidified carbon nanofiber CNF-A comprises the following steps:

[0015] An acid solution is added to carbon nanofibers, refluxed at 80°C-90°C for 3-12 hours, and then washed and filtered to obtain the acidified carbon nanofibers CNF-A. The acid solution is a mixture of 30%-60% HNO3 and 60%-98% H2SO4 in a volume ratio of 1:2-1:4. After acidification, the CNF-A surface has a higher negative charge, which can better absorb positively charged metal ions and ensure uniform adsorption of the metal ions on the surface, thereby facilitating the generation of more reactive sites for subsequent reactions.

[0016] In one embodiment of the present invention, in step (1), the zinc salt is selected from zinc nitrate, zinc sulfate or zinc chloride; the manganese salt is selected from manganese nitrate, manganese chloride or manganese sulfate; the concentration of zinc ions in the mixed solution is 0.015M-0.035M; the concentration ratio of zinc ions to manganese ions is 1:0.5-1:2; and the concentration ratio of 2-methylimidazole to zinc ions in the mixed solution is 3:1-12:1.

[0017] In one embodiment of the present invention, in step (1), the concentration of the acidified carbon nanofiber CNF-A is 2 mg / mL-10 mg / mL.

[0018] In one embodiment of the present invention, in step (1), the mixing is performed by ultrasonic mixing for 20 min to 60 min, so that the zinc ions and manganese ions are adsorbed on the surface of CNF-A by electrostatic adsorption.

[0019] In one embodiment of the present invention, in step (2), the copper salt is selected from copper nitrate, copper sulfate or copper chloride; and the volume ratio of the N,N-dimethylformamide to the ethanol solution is 1:1-1:5.

[0020] In one embodiment of the present invention, in step (3), the reaction temperature is 70°C-90°C, and the time is 18h-32h; the drying temperature is 60°C-120°C, and the time is 6h-24h.

[0021] In one embodiment of the present invention, in step (4), the temperature of the carbonization treatment is 800°C-1000°C.

[0022] The second object of the present invention is to provide a tennis ball flower-shaped Cu@Mn / CNF-A prepared by the method described above.

[0023] The third object of the present invention is to provide an application of the tennis flower-shaped Cu@Mn / CNF-A in electrochemical detection of H2O2.

[0024] The technical solution of the present invention has the following advantages over the prior art:

[0025] (1) The preparation method described in the present invention uses porous acidified carbon nanofiber CNF-A as a substrate, in situ grows a metal organic framework material ZIF-8 on its surface and dopes it with manganese, and then in situ grows a metal organic framework material HKUST-1. The zinc element is removed by carbonization to obtain Cu@Mn / CNF-A with a large specific surface area, uniform distribution of manganese and copper elements, and many reactive sites. Its morphology is different from the polyhedral structure of traditional MOF but is a tennis ball flower structure, which effectively increases the specific surface area of ​​the material, increases the reactive area, and greatly improves its electrocatalytic activity.

[0026] (2) The preparation method of the present invention is simple to operate, has mild conditions and is suitable for large-scale production, and therefore has great application prospects.

[0027] (3) The tennis ball flower-shaped Cu@Mn / CNF-A material described in the present invention is distributed with both copper and manganese active centers that have specific catalytic effects on H2O2. The electrochemical sensor device constructed based on Cu@Mn / CNF-A achieves highly sensitive and specific detection of H2O2 through the synergistic catalytic effect of copper and manganese. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below according to specific embodiments of the present invention in conjunction with the accompanying drawings, wherein:

[0029] Figure 1 This is the SEM image of Cu@Mn / CNF-A of Example 1 of the present invention;

[0030] Figure 2 Figure 1 is a graph showing the electrochemical performance of HKUST-1 / Mn@ZIF-8 / CNF-A and Cu@Mn / CNF-A according to Example 1 of the present invention. Figure A shows the CV responses of HKUST-1 / Mn@ZIF-8 / CNF-A and Cu@Mn / CNF-A to 1 mM H2O2. Figure B shows the current response of Cu@Mn / CNF-A to different concentrations of H2O2.

[0031] Figure 3 This is the selectivity test of Cu@Mn / CNF-A for H2O2 in Example 1 of the present invention. DETAILED DESCRIPTION

[0032] The present invention will be further described below with reference to the accompanying drawings and specific embodiments so that those skilled in the art can better understand the present invention and implement it. However, the embodiments are not intended to limit the present invention.

[0033] Unless otherwise noted, the acidified carbon nanofibers CNF-A described in the examples were prepared as follows: 1 g of CNF powder was placed in a single-necked round-bottom flask, followed by the gradual addition of 5 mL of 60% HNO₃ and 15 mL of 98% concentrated H₂SO₄. The mixture was then sonicated for 30 minutes. The mixture was then heated to 85°C and refluxed for 5 hours. After the reaction, the solution was repeatedly rinsed with water and filtered until near neutral. The filtered CNF-A was dried at 60°C for 24 hours before use.

[0034] Example 1

[0035] A tennis ball flower-shaped Cu@Mn / CNF-A and a preparation method thereof, comprising the following steps:

[0036] (1) First, a certain amount of zinc nitrate and manganese nitrate were weighed and dissolved in secondary water to make the concentration of zinc ion 0.025M and the ratio of zinc ion concentration to manganese ion concentration 1:1; then a certain amount of acidified carbon nanofiber CNF-A was added to make its concentration 5 mg / mL, and ultrasonic mixing was carried out for 30 minutes to allow zinc ions and manganese ions to be adsorbed on the surface of CNF-A by electrostatic adsorption. Then, a certain amount of 2-methylimidazole was added to the above mixed solution to make the concentration ratio of 2-methylimidazole to zinc ion 4:1. After stirring and reacting at room temperature for 24 hours, the mixture was centrifuged and washed with water three times to remove unreacted 2-methylimidazole and metal ions.

[0037] (2) Weigh a certain amount of copper nitrate and dissolve it in N,N-dimethylformamide to a concentration of 0.2 M, and place it in an ultrasonic cleaner for 2 minutes to completely dissolve it; then take a certain amount of trimesic acid (1,3,5-benzenetricarboxylic acid) and add it to the above reaction solution containing copper ions, so that the concentration ratio of copper ions to trimesic acid is 1:1; then add a certain volume of 70% ethanol aqueous solution to the reaction solution, and control the volume ratio of N,N-dimethylformamide to ethanol aqueous solution to be 1:3.

[0038] (3) After the solution is evenly mixed, it is added to the precipitate obtained by centrifugation in step (1) and stirred thoroughly to obtain a dark blue suspension. The beaker containing the dark blue suspension is placed on a magnetic stirrer and stirred at 25°C for 60 minutes. The reaction solution is transferred to a polytetrafluoroethylene reactor liner and reacted at a temperature of 80°C for 24 hours. The dark blue product after the reaction is centrifuged and washed three times with ethanol to obtain a dark blue precipitate. The obtained precipitate is placed in a vacuum drying oven, the temperature is adjusted to 80°C and dried for 12 hours to obtain a dark blue HKUST-1 / Mn@ZIF-8 / CNF-A.

[0039] (4) HKUST-1 / Mn@ZIF-8 / CNF-A was carbonized at 900 °C in an argon atmosphere in a vacuum tube furnace to obtain tennis flower-shaped Cu@Mn / CNF-A.

[0040] Example 2

[0041] A tennis ball flower-shaped Cu@Mn / CNF-A and a preparation method thereof, comprising the following steps:

[0042] (1) First, a certain amount of zinc nitrate and manganese sulfate were weighed and dissolved in secondary water to make the concentration of zinc ions 0.015M and the ratio of zinc ion concentration to manganese ion concentration was 1:0.5; then a certain amount of acidified carbon nanofiber CNF-A was added to make its concentration 2 mg / mL, and ultrasonic mixing was performed for 20 min to allow zinc ions and manganese ions to be adsorbed on the surface of CNF-A by electrostatic adsorption. Then, a certain amount of 2-methylimidazole was added to the above mixed solution to make the concentration ratio of 2-methylimidazole to zinc ions 3:1. After stirring and reacting at room temperature for 12 h, the mixture was centrifuged and washed with water four times to remove unreacted 2-methylimidazole and metal ions.

[0043] (2) Weigh a certain amount of copper nitrate and dissolve it in N,N-dimethylformamide to a concentration of 0.1 M, and place it in an ultrasonic cleaner for 1 minute to completely dissolve it; then take a certain amount of trimesic acid (1,3,5-benzenetricarboxylic acid) and add it to the above reaction solution containing copper ions, so that the concentration ratio of copper ions to trimesic acid is 2:1; then add a certain volume of 50% ethanol aqueous solution to the reaction solution, and control the volume ratio of N,N-dimethylformamide to ethanol aqueous solution to be 1:1.

[0044] (3) After the solution is evenly mixed, it is added to the precipitate obtained by centrifugation in step (1) and stirred thoroughly to obtain a dark blue suspension. The beaker containing the dark blue suspension is placed on a magnetic stirrer and stirred at 15°C for 30 minutes. The reaction solution is transferred to a polytetrafluoroethylene reactor liner and reacted at a temperature of 70°C for 18 hours. The dark blue product after the reaction is washed with ethanol by centrifugation 4 times to obtain a dark blue precipitate. The obtained precipitate is placed in a vacuum drying oven, the temperature is adjusted to 60°C and dried for 24 hours to obtain a dark blue HKUST-1 / Mn@ZIF-8 / CNF-A.

[0045] (4) HKUST-1 / Mn@ZIF-8 / CNF-A was carbonized at 800 °C in an argon atmosphere in a vacuum tube furnace to obtain tennis flower-shaped Cu@Mn / CNF-A.

[0046] Example 3

[0047] A tennis ball flower-shaped Cu@Mn / CNF-A and a preparation method thereof, comprising the following steps:

[0048] (1) First, a certain amount of zinc sulfate and manganese nitrate were weighed and dissolved in secondary water to make the concentration of zinc ions 0.035M and the ratio of zinc ion concentration to manganese ion concentration was 1:2; then a certain amount of acidified carbon nanofiber CNF-A was added to make its concentration 10 mg / mL, and ultrasonic mixing was performed for 60 min to allow zinc ions and manganese ions to be adsorbed on the surface of CNF-A through electrostatic adsorption. Then, a certain amount of 2-methylimidazole was added to the above mixed solution to make the concentration ratio of 2-methylimidazole to zinc ions 12:1. After stirring and reacting at room temperature for 36 h, the mixture was centrifuged and washed with water 5 times to remove unreacted 2-methylimidazole and metal ions.

[0049] (2) Weigh a certain amount of copper sulfate and dissolve it in N,N-dimethylformamide to a concentration of 0.5M, and then place it in an ultrasonic cleaner and ultrasonicate for 5 minutes to completely dissolve it; then take a certain amount of trimesic acid (1,3,5-benzenetricarboxylic acid) and add it to the above reaction solution containing copper ions, so that the concentration ratio of copper ions to trimesic acid is 2:3; then add a certain volume of 90% ethanol aqueous solution to the reaction solution, and control the volume ratio of N,N-dimethylformamide to ethanol aqueous solution to be 1:5.

[0050] (3) After the solution is evenly mixed, it is added to the precipitate obtained by centrifugation in step (1) and stirred thoroughly to obtain a dark blue suspension. The beaker containing the dark blue suspension is placed on a magnetic stirrer and stirred at 30°C for 120 minutes. The reaction solution is transferred to a polytetrafluoroethylene reactor liner and reacted at a temperature of 90°C for 32 hours. The dark blue product after the reaction is washed with ethanol by centrifugation 5 times to obtain a dark blue precipitate. The obtained precipitate is placed in a vacuum drying oven, the temperature is adjusted to 120°C and dried for 6 hours to obtain a dark blue HKUST-1 / Mn@ZIF-8 / CNF-A.

[0051] (4) HKUST-1 / Mn@ZIF-8 / CNF-A was carbonized at 1000 °C in an argon atmosphere in a vacuum tube furnace to obtain tennis ball-shaped Cu@Mn / CNF-A.

[0052] Comparative Example 1

[0053] A certain amount of manganese nitrate was weighed and dissolved in secondary water to make the concentration of manganese ions 0.025M; then a certain amount of CNF-A was added to make its concentration 5mg / mL, and ultrasonic mixing was performed for 30min to allow the manganese ions to be adsorbed on the surface of CNF-A through electrostatic adsorption. Then, a certain amount of 2-methylimidazole was added to the above mixed solution to make the concentration ratio of 2-methylimidazole to manganese ions 4:1. After stirring and reacting at room temperature for 24h, no manganese MOF was formed.

[0054] Test Example 1 Physical Property Characterization

[0055] The Cu@Mn / CNF-A of Example 1 was subjected to SEM test, and the results were as follows: Figure 1 As shown. Figure 1 It can be seen that Cu@Mn / CNF-A has a tennis flower-like structure, and the length of its needle-like structure is 1μm-2μm and the diameter is about 10nm-20nm.

[0056] Test Example 2 Application of Tennis-Tennis Flower-Shaped Cu@Mn / CNF-A Materials in Biosensing

[0057] The solution of Example 1 was prepared into a 6 mg / mL aqueous solution, and 5 μL was taken to modify the screen-printed electrode. After drying at room temperature, the electrochemical sensor was constructed. The electrochemical performance of the Cu@Mn / CNF-A modified electrode with H2O2 was tested by cyclic voltammetry (CV) and chronoamperometry.

[0058] The responses of the electrodes prepared by HKUST-1 / Mn@ZIF-8 / CNF-A and Cu@Mn / CNF-A to 1 mM H2O2 were compared by electrochemical workstation. Figure 2 As shown in A, the results show that the current response of Cu@Mn / CNF-A to 1mM H2O2 (dashed line) is significantly higher than the current response of HKUST-1 / Mn@ZIF-8 / CNF-A to 1mM H2O2 (solid line), indicating that the in-situ growth of MOF on CNF-A and the evaporation of Zn after carbonization lead to an increase in the specific surface area of ​​the material. The doping of Mn increases the reaction active sites and significantly improves the sensing performance of the material to H2O2. In addition, the current response of the electrode prepared by Cu@Mn / CNF-A to different concentrations of H2O2 was tested. Figure 2 As shown in Figure B, the results show that Cu@Mn / CNF-A has a good response to 0.5-3mM H2O2.

[0059] In addition, the specificity of Cu@Mn / CNF-A in testing H2O2 was evaluated by chronoamperometry. The results of chronoamperometry test are shown in Figure 2. Figure 3 As shown. Figure 3 It can be seen that an obvious response current appeared after adding 500 μM H2O2 in 0.01 M PBS, while no obvious response current appeared after adding the same concentration of glucose (Glu), ascorbic acid (AA), dopamine (DA) and uric acid (UA), indicating that Cu@Mn / CNF-A has good selectivity for H2O2 detection.

[0060] Obviously, the above embodiments are merely examples for clarity of explanation and are not intended to limit the implementation methods. Those skilled in the art will appreciate that other variations or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation methods here. Obvious variations or modifications arising therefrom remain within the scope of protection of the present invention.

Claims

1. A method for preparing tennis flower-shaped Cu@Mn / CNF-A, characterized in that: The following steps are included: Using acidified carbon nanofiber CNF-A as a substrate, a metal organic framework material ZIF-8 was in situ grown on its surface and manganese doped, followed by in situ growth of a metal organic framework material HKUST-1, and finally the tennis ball flower-shaped Cu@Mn / CNF-A was obtained by carbonization treatment; Specifically include the following steps: (1) adding acidified carbon nanofiber CNF-A to a mixed solution of zinc salt and manganese salt, mixing well, adding 2-methylimidazole, and reacting for 12 h to 36 h to obtain a reaction solution; (2) dissolving copper salt and trimesic acid in N,N-dimethylformamide to obtain a copper salt concentration of 0.1M-0.5M and a concentration ratio of copper ions in the copper salt to trimesic acid of 2:1-2:3, and then adding 50%-90% ethanol solution to obtain a mixed solution; (3) adding the mixed solution described in step (2) to the reaction solution described in step (1), centrifuging, washing, and drying after the reaction to obtain HKUST-1 / Mn@ZIF-8 / CNF-A; the reaction temperature is 70°C-90°C, and the reaction time is 18h-32h; (4) Under a protective atmosphere, the HKUST-1 / Mn@ZIF-8 / CNF-A described in step (3) is carbonized to obtain the tennis ball-shaped Cu@Mn / CNF-A.

2. The method for preparing tennis flower-shaped Cu@Mn / CNF-A according to claim 1, wherein In step (1), the method for preparing the acidified carbon nanofiber CNF-A comprises the following steps: Acid solution is added to the carbon nanofibers, refluxed at 80°C-90°C for 3h-12h, and the acidified carbon nanofibers CNF-A are obtained by washing and filtering; the acid solution is obtained by mixing HNO3 with a mass fraction of 30%-60% and H2SO4 with a volume ratio of 1:2-1:

4.

3. The method for preparing the tennis flower-shaped Cu@Mn / CNF-A according to claim 1, wherein: In step (1), the zinc salt is selected from zinc nitrate, zinc sulfate or zinc chloride; the manganese salt is selected from manganese nitrate, manganese chloride or manganese sulfate; the concentration of zinc ions in the mixed solution is 0.015M-0.035M; the concentration ratio of zinc ions to manganese ions is 1:0.5-1:2; the concentration ratio of 2-methylimidazole to zinc ions in the mixed solution is 3:1-12:

1.

4. The method for preparing the tennis flower-shaped Cu@Mn / CNF-A according to claim 1, wherein: In step (1), the concentration of the acidified carbon nanofiber CNF-A is 2 mg / mL-10 mg / mL.

5. The method for preparing the tennis flower-shaped Cu@Mn / CNF-A according to claim 1, wherein: In step (2), the copper salt is selected from copper nitrate, copper sulfate or copper chloride; and the volume ratio of the N,N-dimethylformamide to the ethanol solution is 1:1-1:

5.

6. The method for preparing the tennis flower-shaped Cu@Mn / CNF-A according to claim 1, characterized in that: In step (3), the drying temperature is 60°C-120°C, and the drying time is 6h-24h.

7. The method for preparing the tennis flower-shaped Cu@Mn / CNF-A according to claim 1, wherein: In step (4), the temperature of the carbonization treatment is 800°C-1000°C.

8. Tennis ball flower-shaped Cu@Mn / CNF-A prepared according to the method according to any one of claims 1 to 7.

9. Use of the tennis ball flower-shaped Cu@Mn / CNF-A according to claim 8 in electrochemical detection of H2O2.

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