A Fe-pCOFs-MWCNTs / MoS2 nanocomposite material and its preparation method and application

Abstract

The present invention relates to the field of nanomaterial preparation and molecular recognition technology, and specifically discloses a Fe‑pCOFs‑MWCNTs / MoS2 nanocomposite material, a preparation method thereof, and an application thereof. The nanocomposite material provided by the present invention comprises nano-flower-shaped molybdenum disulfide microspheres, and a sheet-like iron porphyrin-based covalent organic framework material and multi-walled carbon nanotubes loaded on the nano-flower-shaped molybdenum disulfide microspheres. Among them, the sheet-like iron porphyrin-based covalent organic framework material has a high specific surface area, which improves the atomic utilization rate and mass transfer rate. When the nano-flower-shaped molybdenum disulfide microspheres are used as co-catalysts, they are conducive to forming an efficient catalytic cycle at the electrode interface. Multi-walled carbon nanotubes as conductive agents further accelerate the rate of electronic reaction. The three act synergistically, greatly improving the sensitivity and selectivity of the electrochemical sensor for hydrogen peroxide detection.

Description

Technical Field

[0001] The present invention relates to the technical field of nanomaterial preparation and molecular recognition, and in particular to a Fe-pCOFs-MWCNTs / MoS2 nanocomposite material and a preparation method and application thereof. Background Art

[0002] H2O2 is a key reactive oxygen molecule that plays a vital role in physiological processes such as cellular metabolism and signal transduction, and is a byproduct of numerous biological processes. However, H2O2 concentration levels are a crucial biological parameter for monitoring and maintaining the physiological balance of living cells. When H2O2 concentrations exceed the normal range, the human body may be harmed by excessive oxidative stress and cellular damage, leading to serious illnesses such as myocardial infarction, Parkinson's disease, Alzheimer's disease, and even cancer. Therefore, sensitive, real-time monitoring of H2O2 released by living cells is crucial for early cancer diagnosis and the study of pathological processes.

[0003] Currently, a variety of analytical techniques have been applied to the detection of H2O2, including colorimetry, chemiluminescence, fluorescence, and electrochemistry. A number of enzyme-based electrochemical sensors have been reported for H2O2 determination. However, biological enzymes often suffer from limitations such as high cost, complex immobilization processes, and susceptibility to inactivation due to environmental pH and temperature. These limitations not only lead to high cost and complex operation, but also result in poor selectivity and low sensitivity of electrochemical sensors. Therefore, the development of specific and sensitive electrochemical sensors is of great practical significance for the rapid and trace monitoring of H2O2. Summary of the Invention

[0004] In view of the fact that existing electrochemical sensors for detecting H2O2 still have the problems of poor selectivity and low sensitivity, the present invention provides a Fe-pCOFs-MWCNTs / MoS2 nanocomposite material, a preparation method and application thereof.

[0005] To solve the above technical problems, the technical solution 1 provided by the embodiment of the present invention is:

[0006] A Fe-pCOFs-MWCNTs / MoS2 nanocomposite material comprises nano-flower-shaped molybdenum disulfide microspheres, and sheet-like iron porphyrin-based covalent organic framework materials and multi-walled carbon nanotubes loaded on the nano-flower-shaped molybdenum disulfide microspheres.

[0007] Compared with the prior art, the Fe-pCOFs-MWCNTs / MoS2 nanocomposite material provided by the present invention has completely dispersed metal sites in the sheet-like iron porphyrin-based covalent organic framework material, thereby improving its electrochemical performance and greatly improving the atomic utilization rate and mass transfer rate. Furthermore, the inventors have found through extensive research that, on the premise of using nano-flower-like molybdenum disulfide microspheres as the basic material, by loading the sheet-like iron porphyrin-based covalent organic framework material and multi-walled carbon nanotubes, the Fe-pCOFs-MWCNTs / MoS2 nanocomposite material has a larger surface area, which is also conducive to the formation of rich and uniform dispersed sites. When applied to the sensing field, it can greatly improve the sensitivity of the electrochemical sensor in detecting hydrogen peroxide. The nano-flower-like molybdenum disulfide microspheres, when used as a co-catalyst, are conducive to the formation of an efficient catalytic cycle at the electrode interface, and the multi-walled carbon nanotubes, as a conductive agent, further accelerate the rate of the electronic reaction. The three, through synergistic action, greatly improve the sensitivity and selectivity of the electrochemical sensor for hydrogen peroxide detection.

[0008] Preferably, the sheet-like iron porphyrin-based covalent organic framework material is prepared by condensation reaction of an aminoporphyrin monomer, a first aldehyde monomer and a second aldehyde monomer.

[0009] Preferably, the aminoporphyrin monomer is 5,10,15,20-tetrakis(4-aminophenyl)-21H,23H-porphyrin.

[0010] Preferably, the first aldehyde monomer is 2,4,6-trimethylbenzaldehyde.

[0011] Preferably, the second aldehyde monomer is 4,4'-biphenyldicarboxaldehyde.

[0012] Preferably, the mass ratio of the sheet-like iron porphyrin-based covalent organic framework material, the nano-flower-shaped molybdenum disulfide microspheres and the multi-walled carbon nanotubes is 1:(2.8-3):1.

[0013] The optimal mass ratio further improves the sensitivity of the composite material when applied in the field of sensing.

[0014] The present invention also provides a method for preparing the above-mentioned Fe-pCOFs-MWCNTs / MoS2 nanocomposite material, comprising the following preparation steps:

[0015] Step a, uniformly mixing an aminoporphyrin monomer, a first aldehyde monomer, mesitylene, and acetic acid, adding an alcohol solution of a second aldehyde monomer, mixing uniformly, and reacting at 115° C. to 125° C. to obtain a primary reaction liquid; centrifuging the primary reaction liquid, collecting a supernatant, centrifuging the supernatant, performing solid-liquid separation, washing, and drying to obtain a porphyrin-based covalent organic framework material;

[0016] Step b, dispersing the porphyrin-based covalent organic framework material and ferrous sulfate in an organic solvent, reacting at 18° C.-28° C., solid-liquid separation, washing, and drying to obtain a sheet-like iron porphyrin-based covalent organic framework material;

[0017] Step c, dissolving molybdate and thiourea in water, reacting at 195° C.-205° C., solid-liquid separation, washing, and drying to obtain the nano-flower-shaped molybdenum disulfide microspheres;

[0018] Step d: dispersing the sheet-like iron porphyrin-based covalent organic framework material, nano-flower-shaped molybdenum disulfide microspheres and multi-walled carbon nanotubes in water, centrifuging, and drying to obtain the Fe-pCOFs-MWCNTs / MoS2 nanocomposite material.

[0019] Preferably, in step a, the aminoporphyrin monomer is 5,10,15,20-tetrakis(4-aminophenyl)-21H,23H-porphyrin.

[0020] Preferably, in step a, the first aldehyde monomer is 2,4,6-trimethylbenzaldehyde.

[0021] Preferably, in step a, the alcohol solution is ethanol.

[0022] Preferably, in step a, the second aldehyde monomer is 4,4'-biphenyldicarboxaldehyde.

[0023] Preferably, in step a, the molar ratio of the aminoporphyrin monomer, the first aldehyde monomer, mesitylene and acetic acid is 1 mol:(39-41) mol:(348-352) mol:(58-62) mol.

[0024] Preferably, in step a, the molar ratio of the aminoporphyrin monomer to the second aldehyde monomer is 1:(2-2.2).

[0025] Preferably, in step a, the concentration of the second aldehyde monomer in the alcohol solution is 0.04-0.05 mol / L.

[0026] Preferably, in step a, the reaction time is 11h-13h.

[0027] Preferably, in step b, the mass ratio of the porphyrin-based covalent organic framework material to ferrous sulfate is 1:(1.2-1.4).

[0028] Preferably, in step b, the organic solvent is a mixed solution of dichloromethane and methanol in a volume ratio of 1:(0.8-1.2).

[0029] Preferably, in step b, the mass volume ratio of the porphyrin-based covalent organic framework material and the organic solvent is 1g:(0.5-0.7)L.

[0030] Preferably, in step b, the reaction time is 32h-38h.

[0031] Preferably, in step c, the molybdate is sodium molybdate.

[0032] Preferably, in step c, the molar ratio of molybdate to thiourea is 1:(5.8-6.2).

[0033] Preferably, in step c, the reaction time is 24h-26h.

[0034] Preferably, in step d, the total concentration of the sheet-like iron porphyrin-based covalent organic framework material, nanoflower-shaped molybdenum disulfide microspheres and multi-walled carbon nanotubes in water is 1 mg / mL-1.2 mg / mL.

[0035] Further preferably, the mass ratio of the sheet-like porphyrin-based covalent organic framework material, the nano-flower-like molybdenum disulfide microspheres and the multi-walled carbon nanotubes is 1:(2.8-3):1

[0036] The technical solution 2 provided by the embodiment of the present invention is:

[0037] An electrochemical sensor based on an iron porphyrin-based covalent organic framework material comprises a GCE electrode and a Fe-pCOFs-MWCNTs / MoS2 nanocomposite material wrapped around the GCE electrode.

[0038] Compared with the prior art, the electrochemical sensor based on iron porphyrin-based covalent organic framework material provided by the present invention includes a sheet-like iron porphyrin-based covalent organic framework material in the Fe-pCOFs-MWCNTs / MoS2 nanocomposite material having a large specific surface area and abundant active sites, which can increase the contact area with hydrogen peroxide and catalyze its reduction reaction. The introduction of nano-flower-like molybdenum disulfide microspheres can further enhance the catalytic reduction of hydrogen peroxide and improve the catalytic efficiency. The addition of multi-walled carbon nanotubes greatly promotes the electron transfer rate between the sheet-like iron porphyrin-based covalent organic framework material and the nano-flower-like molybdenum disulfide microspheres. The three materials of sheet-like iron porphyrin-based covalent organic framework material, nano-flower-like molybdenum disulfide microspheres and multi-walled carbon nanotubes work synergistically to greatly improve the sensitivity and selectivity of the electrochemical sensor, and further reduce the detection limit, thereby solving the problems of high cost and complex operation of existing electrochemical sensors and having broad application prospects.

[0039] The present invention provides a method for preparing the electrochemical sensor based on the iron porphyrin-based covalent organic framework material, comprising the following preparation steps:

[0040] Step 1, dispersing the weighed Fe-pCOFs-MWCNTs / MoS2 nanocomposite material in water to obtain a Fe-pCOFs-MWCNTs / MoS2 nanocomposite material dispersion;

[0041] In step 2, the Fe-pCOFs-MWCNTs / MoS2 nanocomposite dispersion droplets are applied to the surface of the GCE electrode and dried to obtain an electrochemical sensor based on the iron porphyrin-based covalent organic framework material.

[0042] Preferably, in step 1, the concentration of the Fe-pCOFs-MWCNTs / MoS2 nanocomposite dispersion is 1 mg / mL-1.2 mg / mL.

[0043] If the concentration is too low, there will be fewer catalytic active sites, poor catalytic effect, and poor sensitivity; if the concentration is too high, the electrode layer will be too thick, which will hinder the transmission of interfacial electronic signals and result in low response sensitivity. The optimal concentration is beneficial to improving the sensitivity of the electrochemical sensor and reducing the detection limit.

[0044] The present invention also provides the use of the above-mentioned Fe-pCOFs-MWCNTs / MoS2 nanocomposite material or the above-mentioned electrochemical sensor based on the iron porphyrin-based covalent organic framework material in detecting hydrogen peroxide. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 TEM image of pCOFs prepared in Example 1 of the present invention;

[0046] Figure 2 This is a SEM image of MoS2 prepared in Example 1 of the present invention;

[0047] Figure 3 TEM image of Fe-pCOFs-MWCNTs / MoS2 prepared in Example 1 of the present invention;

[0048] Figure 4 Different modified electrodes prepared in Example 1 of the present invention were prepared in the presence of 5.0 mM [Fe(CN)6] 3- CV response graph in 0.1M KCl solution;

[0049] Figure 5 Different modified electrodes prepared in Example 1 of the present invention were prepared in the presence of 5.0 mM [Fe(CN)6] 3- / 4- EIS diagram in 0.1M KCl solution;

[0050] Figure 6 CV response diagrams of different modified electrodes prepared in Example 1 of the present invention in 0.1 M PBS solution containing 5.0 mM H2O2;

[0051] Figure 7 It curve of the Fe-pCOFs-MWCNTs / MoS2 / GCE electrochemical sensor prepared in Example 1 of the present invention in 0.1M PBS buffer solution (pH 7.4) containing different concentrations of H2O2 (20-2650 μM);

[0052] Figure 8 This is a linear relationship diagram of the response current intensity and hydrogen peroxide concentration change of the Fe-pCOFs-MWCNTs / MoS2 / GCE electrochemical sensor prepared in Example 1 of the present invention when detecting H2O2;

[0053] Figure 9 This is the current response diagram of the Fe-pCOFs-MWCNTs / MoS2 / GCE electrochemical sensor prepared in Example 1 of the present invention when H2O2 and interfering substances are continuously added to a blank PBS buffer;

[0054] Figure 10 This is a reproducibility test of Fe-pCOFs-MWCNTs / MoS2 / GCE prepared in Example 1 of the present invention;

[0055] Figure 11 This is a test diagram of Fe-pCOFs-MWCNTs / MoS2 / GCE prepared in Example 1 of the present invention in actual sample detection. DETAILED DESCRIPTION

[0056] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0057] In order to better illustrate the present invention, further examples are given below.

[0058] Example 1

[0059] Preparation of Fe-pCOFs-MWCNTs / MoS2 nanocomposites:

[0060] Step a, 5,10,15,20-tetrakis(4-aminophenyl)-21H,23H-porphyrin (1 mmol), 2,4,6-trimethylbenzaldehyde (39 mmol), mesitylene (352 mmol) and acetic acid (58 mmol) were mixed evenly, and then an ethanol solution of 4,4'-biphenyldicarboxaldehyde (2.2 mmol) was added (the concentration of 4,4'-biphenyldicarboxaldehyde in ethanol was 0.05 mol / L), mixed evenly, and reacted at 115° C. for 12 hours to obtain a primary reaction solution; the primary reaction solution was centrifuged at a rate of 2000 rpm for 10 minutes, the upper dispersion was collected, and the upper dispersion was centrifuged at a rate of 10000 rpm, solid-liquid separation was performed, washed, and dried to obtain a porphyrin-based covalent organic framework material;

[0061] Step b, dispersing the porphyrin-based covalent organic framework material (10 mg) and ferrous sulfate (12 mg) in an organic solvent (5 mL), reacting at 28° C. for 32 hours, solid-liquid separation, washing, and drying to obtain a sheet-like iron porphyrin-based covalent organic framework material; wherein the organic solvent is a mixed solution of dichloromethane and methanol in a volume ratio of 1:0.8;

[0062] Step c, dissolving sodium molybdate (1 mmol) and thiourea (5.8 mmol) in water, reacting at 205° C. for 24 h, solid-liquid separation, washing, and drying to obtain the nano-flower-shaped molybdenum disulfide microspheres;

[0063] Step d, dispersing the flaky iron porphyrin-based covalent organic framework material, nanoflower-shaped molybdenum disulfide microspheres and multi-walled carbon nanotubes in water (total concentration is 1 mg / mL), centrifuging, and drying to obtain the Fe-pCOFs-MWCNTs / MoS2 nanocomposite material; wherein the mass ratio of the flaky iron porphyrin-based covalent organic framework material, nanoflower-shaped molybdenum disulfide microspheres and multi-walled carbon nanotubes is 1:3:1.

[0064] Preparation of Fe-pCOFs-MWCNTs / MoS2 / GCE electrochemical sensor:

[0065] Step 1: polish the glassy carbon electrode with 1.0, 0.3, and 0.05 μm aluminum oxide powder on a polishing plate, respectively. After each polishing, ultrasonically clean the electrode in water, anhydrous ethanol, and water, and blow dry it with nitrogen before use.

[0066] Step 2, dispersing the weighed Fe-pCOFs-MWCNTs / MoS2 nanocomposite material in water to obtain a Fe-pCOFs-MWCNTs / MoS2 nanocomposite material dispersion with a concentration of 1 mg / mL;

[0067] Step 3: Take 6 μL of Fe-pCOFs-MWCNTs / MoS2 nanocomposite dispersion droplets and apply them on the surface of the glassy carbon electrode and dry them to obtain the Fe-pCOFs-MWCNTs / MoS2 / GCE electrochemical sensor based on iron porphyrin-based covalent organic framework materials.

[0068] Example 2

[0069] Preparation of Fe-pCOFs-MWCNTs / MoS2 nanocomposites:

[0070] Step a, 5,10,15,20-tetrakis(4-aminophenyl)-21H,23H-porphyrin (1 mmol), 2,4,6-trimethylbenzaldehyde (41 mmol), mesitylene (348 mmol) and acetic acid (62 mmol) were mixed evenly, and then an ethanol solution of 4,4'-biphenyldicarboxaldehyde (2 mmol) was added (the concentration of 4,4'-biphenyldicarboxaldehyde in ethanol was 0.04 mol / L), mixed evenly, and reacted at 120°C for 12 hours to obtain a primary reaction solution; the primary reaction solution was centrifuged at a rate of 2000 rpm for 10 minutes, the upper dispersion was collected, and the upper dispersion was centrifuged at a rate of 10000 rpm, solid-liquid separation was performed, washed, and dried to obtain a porphyrin-based covalent organic framework material;

[0071] Step b, dispersing the porphyrin-based covalent organic framework material (10 mg) and ferrous sulfate (14 mg) in an organic solvent (7 mL), reacting at 18° C. for 38 h, solid-liquid separation, washing, and drying to obtain a sheet-like iron porphyrin-based covalent organic framework material; wherein the organic solvent is a mixed solution of dichloromethane and methanol in a volume ratio of 1:1.2;

[0072] Step c, dissolving sodium molybdate (1 mmol) and thiourea (6.2 mmol) in water, reacting at 195° C. for 26 h, solid-liquid separation, washing, and drying to obtain the nano-flower-shaped molybdenum disulfide microspheres;

[0073] Step d, dispersing the flaky iron porphyrin-based covalent organic framework material, nanoflower-shaped molybdenum disulfide microspheres and multi-walled carbon nanotubes in water (total concentration is 1.2 mg / mL), centrifuging, and drying to obtain the Fe-pCOFs-MWCNTs / MoS2 nanocomposite material; wherein the mass ratio of the flaky iron porphyrin-based covalent organic framework material, nanoflower-shaped molybdenum disulfide microspheres and multi-walled carbon nanotubes is 1:2.8:1.

[0074] Preparation of Fe-pCOFs-MWCNTs / MoS2 / GCE electrochemical sensor:

[0075] Step 1: polish the glassy carbon electrode with 1.0, 0.3, and 0.05 μm aluminum oxide powder on a polishing plate, respectively. After each polishing, ultrasonically clean the electrode in water, anhydrous ethanol, and water, and blow dry it with nitrogen before use.

[0076] Step 2, dispersing the weighed Fe-pCOFs-MWCNTs / MoS2 nanocomposite material in water to obtain a Fe-pCOFs-MWCNTs / MoS2 nanocomposite material dispersion with a concentration of 1.2 mg / mL;

[0077] Step 3: Take 6 μL of Fe-pCOFs-MWCNTs / MoS2 nanocomposite dispersion droplets and apply them on the surface of the glassy carbon electrode and dry them to obtain the Fe-pCOFs-MWCNTs / MoS2 / GCE electrochemical sensor based on iron porphyrin-based covalent organic framework materials.

[0078] Example 3

[0079] Preparation of Fe-pCOFs-MWCNTs / MoS2 nanocomposites:

[0080] Step a, 5,10,15,20-tetrakis(4-aminophenyl)-21H,23H-porphyrin (1 mmol), 2,4,6-trimethylbenzaldehyde (40 mmol), mesitylene (350 mmol) and acetic acid (60 mmol) were mixed evenly, and then an ethanol solution of 4,4'-biphenyldicarboxaldehyde (2.1 mmol) was added (the concentration of 4,4'-biphenyldicarboxaldehyde in ethanol was 0.045 mol / L), mixed evenly, and reacted at 120°C for 11 hours to obtain a primary reaction solution; the primary reaction solution was centrifuged at a rate of 2000 rpm for 10 minutes, the upper dispersion was collected, and the upper dispersion was centrifuged at a rate of 10000 rpm, solid-liquid separation was performed, washed, and dried to obtain a porphyrin-based covalent organic framework material;

[0081] Step b, dispersing the porphyrin-based covalent organic framework material (10 mg) and ferrous sulfate (13 mg) in an organic solvent (6 mL), reacting at 25° C. for 35 h, solid-liquid separation, washing, and drying to obtain a sheet-like iron porphyrin-based covalent organic framework material; wherein the organic solvent is a mixed solution of dichloromethane and methanol in a volume ratio of 1:1;

[0082] Step c, dissolving sodium molybdate (1 mmol) and thiourea (6 mmol) in water, reacting at 200° C. for 25 h, solid-liquid separation, washing, and drying to obtain the nano-flower-shaped molybdenum disulfide microspheres;

[0083] Step d, dispersing the flaky iron porphyrin-based covalent organic framework material, nanoflower-shaped molybdenum disulfide microspheres and multi-walled carbon nanotubes in water (total concentration is 1.1 mg / mL), centrifuging, and drying to obtain the Fe-pCOFs-MWCNTs / MoS2 nanocomposite material; wherein the mass ratio of the flaky iron porphyrin-based covalent organic framework material, nanoflower-shaped molybdenum disulfide microspheres and multi-walled carbon nanotubes is 1:2.9:1.

[0084] Preparation of Fe-pCOFs-MWCNTs / MoS2 / GCE electrochemical sensor:

[0085] Step 1: polish the glassy carbon electrode with 1.0, 0.3, and 0.05 μm aluminum oxide powder on a polishing plate, respectively. After each polishing, ultrasonically clean the electrode in water, anhydrous ethanol, and water, and blow dry it with nitrogen before use.

[0086] Step 2, dispersing the weighed Fe-pCOFs-MWCNTs / MoS2 nanocomposite material in water to obtain a Fe-pCOFs-MWCNTs / MoS2 nanocomposite material dispersion with a concentration of 1.1 mg / mL;

[0087] Step 3: Take 6 μL of Fe-pCOFs-MWCNTs / MoS2 nanocomposite material dispersion droplets and apply them on the surface of the glassy carbon electrode. Dry them to obtain the Fe-pCOFs-MWCNTs / MoS2 / GCE electrochemical sensor based on iron porphyrin-based covalent organic framework material (hereinafter abbreviated as Fe-pCOFs-MWCNTs / MoS2 / GCE).

[0088] Example 4

[0089] The electrochemical sensor prepared in Example 1 was used for electrochemical testing:

[0090] (1) Characterization of different nanomaterials

[0091] The microstructure and size of different materials were characterized by SEM and TEM. Figure 1 As shown, porphyrin-based covalent organic framework materials (hereinafter abbreviated as pCOFs) present a thin sheet structure similar to graphene. Its transparent appearance indicates that pCOFs have ultra-thin characteristics, which is conducive to the transmission of electrons between electrode interfaces. Figure 2 This indicates that the nanoflower-like molybdenum disulfide microspheres (hereinafter referred to as MoS2) are nanoflower-like microsphere structures formed by self-assembly of nanosheets. In addition, the morphology of the Fe-pCOFs-MWCNTs / MoS2 nanocomposite material was characterized. Figure 3The MoS2 is surrounded by a sheet-like iron porphyrin-based covalent organic framework (Fe-pCOFs) and multi-walled carbon nanotubes (MWCNTs). These results demonstrate the successful preparation of the Fe-pCOFs-MWCNTs / MoS2 nanocomposite. Furthermore, electron microscopy reveals that the resulting Fe-pCOFs-MWCNTs / MoS2 nanocomposite possesses a large surface area. This structural feature facilitates the formation of abundant and evenly dispersed active sites, a desirable property for electrochemical sensor applications. Therefore, the composite is suitable as an electrode modification material to enhance sensor sensitivity.

[0092] (2) Electrochemical characterization of different modified electrodes

[0093] The GCE electrode, Fe-pCOFs-MWCNTs / MoS2 / GCE electrode, Fe-pCOFs / MoS2 / GCE electrode, MoS2 / GCE electrode, Fe-pCOFs / GCE electrode and pCOFs / GCE electrode were used to measure the content of 5.0 mM [Fe(CN)6] 3- The CV response in the example is 100 mV·s. -1 ,like Figure 4 As shown, all electrodes are [Fe(CN)6] 3- Both show a pair of Fe 2+ / Fe 3+ The reversible redox peak of the pCOFs / MWCNTs / MoS2 / GCE is shown in Figure 2. The order of the oxidation peak current is: Fe-pCOFs-MWCNTs / MoS2 / GCE>Fe-pCOFs / MoS2 / GCE>MoS2 / GCE>Fe-pCOFs / GCE>GCE>pCOFs / GCE. Due to the poor conductivity of pCOFs, the oxidation peak current of the pCOFs / GCE electrode is lower than that of the GCE electrode. However, the Fe-pCOFs electrode obtained by post-modification will carry positively charged Fe 2+ , will react with [Fe(CN)6] 3- Electrostatic attraction is generated between the two, promoting electron transfer and enhancing the oxidation current of the Fe-pCOFs / GCE electrode. MoS2 has a high specific surface area and large capacitance, and the modified MoS2 / GCE electrode exhibits a strong current response. When compounded with Fe-pCOFs, the two interact synergistically, further enhancing the current. Moreover, the introduction of MWCNTs further enhances the conductivity, and the Fe-pCOFs-MWCNTs / MoS2 / GCE electrode exhibits the highest current response. These experimental results further demonstrate the successful synthesis of the Fe-pCOFs-MWCNTs / MoS2 nanocomposite material.

[0094] In order to evaluate the electron transfer performance of different electrodes, the GCE electrode, Fe-pCOFs-MWCNTs / MoS2 / GCE electrode, Fe-pCOFs / MoS2 / GCE electrode, MoS2 / GCE electrode, Fe-pCOFs / GCE electrode and pCOFs / GCE electrode were added with 5.0 mM [Fe(CN)6] 3- / 4- EIS test was carried out in KCl solution, and ZSimpWin software was used to simulate EIS data with an equivalent circuit model. Figure 5 As shown in the figure, due to the lack of charge on the surface of pCOFs, the impedance value of pCOFs / GCE is higher than that of GCE. 2+ will be distributed on the surface of pCOFs, increasing the electron migration rate of the electrode and reducing the impedance value. On the contrary, the surface of MoS2 has a negative charge, which is close to [Fe(CN)6] 3- Electrostatic repulsion occurs. When modified, the semicircle diameter in the spectrum increases significantly, indicating a high charge transfer resistance. When Fe-pCOFs and MoS2 are combined, the resistance decreases slightly, and the impedance reaches a minimum when the Fe-pCOFs / MoS2 is further combined with MWCNTs. This indicates that the Fe-pCOFs-MWCNTs / MoS2 nanocomposite has high conductivity and is suitable as an electrode modification material for the construction of hydrogen peroxide electrochemical sensors.

[0095] (3) Electrochemical response of different modified electrodes to hydrogen peroxide

[0096] In order to explore the electrocatalytic behavior of nanocomposites towards hydrogen peroxide, Fe-pCOFs-MWCNTs / MoS2 / GCE electrode, Fe-pCOFs / MoS2 / GCE electrode, MoS2 / GCE electrode, Fe-pCOFs / GCE electrode and pCOFs / GCE electrode were added into 0.1M PBS solution containing 5.0mM H2O2, and the electrochemical response of hydrogen peroxide on electrodes modified with different materials was tested by CV method. Figure 6 As shown, hydrogen peroxide has a reduction peak current response on electrodes with different modified materials, and the order of peak current intensity is: Fe-pCOFs-MWCNTs / MoS2 / GCE>Fe-pCOFs / MoS2 / GCE>MoS2 / GCE>Fe-pCOFs / GCE>pCOFs / GCE. 2+ The prepared Fe-pCOFs / GCE showed a higher current response than that of pCOFs / GCE, which may be due to the presence of Fe 2+The reactive centers promote the electrocatalytic reduction of Fe-pCOFs / MoS2. MoS2's large surface area and uncoordinated Mo-S structure at the edges expose highly active edge sites, resulting in excellent electrocatalytic activity for H2O2. When MoS2 is composited with Fe-pCOFs, the resulting Fe-pCOFs / MoS2 / GCE exhibits a further enhanced electrochemical response to hydrogen peroxide, with the maximum response current achieved after the addition of MWCNTs. In summary, the Fe-pCOFs-MWCNTs / MoS2 nanocomposite is suitable as an electrode modification material for the construction of enzyme-free hydrogen peroxide electrochemical sensors.

[0097] (4) Quantitative detection of hydrogen peroxide using an electrochemical sensor based on iron porphyrin-based covalent organic framework materials

[0098] Figure 7 To cumulatively inject a certain concentration and volume of H2O2 solution into the continuously stirred PBS, the amperometric current response of Fe-pCOFs-MWCNTs / MoS2 / GCE was recorded at an applied potential of -0.4 V. Figure 8 As shown in Figure 2, with the continuous addition of H2O2, the reduction current increases linearly and shows a good linear relationship in the concentration range of 20 to 2650 μM. The linear equation is I / μA = 0.029c / μM-1.6764(R 2 =0.9981), the sensitivity of the modified electrode is 410 μA·mM -1 cm -2 At a signal-to-noise ratio of 3, the detection limit was calculated to be 2.2 μM.

[0099] (5) Performance evaluation of electrochemical sensors based on iron porphyrin-based covalent organic framework materials

[0100] Since interfering substances such as glucose and ascorbic acid usually coexist with H2O2, selectivity is one of the important performance indicators of non-enzymatic H2O2 sensors. Figure 9As shown in the figure, the experiment recorded the current response of Fe-pCOFs-MWCNTs / MoS2 / GCE when 50μM H2O2 and 5 times the interference substances (including Glu, AA, UA, NaNO2, NaCl, MgCl2) were added in sequence at a potential of -0.4V through the it curve. It can be seen that Fe-pCOFs-MWCNTs / MoS2 / GCE immediately produced a significant current response after the addition of 50μM H2O2, while the amperometric response current value of H2O2 remained basically unchanged after the addition of high concentration interference substances, which was almost negligible, proving that the sensor has good anti-interference ability. When H2O2 was added again, a significant current response was again shown. It can be seen that the constructed sensor can selectively detect H2O2 in the presence of high concentrations of interfering substances, and the sensor has high selectivity.

[0101] Based on the good electrochemical performance, Fe-pCOFs-MWCNTs / MoS2 nanocomposites can be used as a new class of electrode materials for electrochemical applications, so the reproducibility and stability tests are very important. In order to evaluate the reproducibility of the proposed sensor, the it response of 5 Fe-pCOFs-MWCNTs / MoS2 / GCE to 50μM H2O2 was measured in parallel under the same experimental conditions. Figure 10 As shown, the corresponding currents of the five electrodes to H2O2 are basically the same, with a current change of about 2.6 μA and a calculated RSD of 3.4%, which clearly shows that the electrochemical sensor exhibits good reproducibility.

[0102] (6) Application of electrochemical sensors based on iron porphyrin-based covalent organic framework materials in actual samples

[0103] Using MCF-7 cells as a model, AA stimulant was added to release H2O2 in the cells, and the H2O2 level in the cancer cell MCF-7 was evaluated by real-time detection of the response changes of the current. Figure 11 As shown, the addition of 20 μM AA to PBS containing MCF-7 cells enhanced the current to a certain extent, with a current change of approximately 200 nA. In contrast, no significant current change was observed when AA was added to blank PBA, confirming that the detected H2O2 originated from MCF-7 cells. These results validate the application of the developed sensor based on iron porphyrin-based covalent organic framework materials for real-time detection of extracellular H2O2 secreted by living cells, providing a new method for the detection of trace amounts of H2O2 in biomedicine.

[0104] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A Fe-pCOFs-MWCNTs / MoS2 nanocomposite material, characterized in that: The invention comprises nano-flower-shaped molybdenum disulfide microspheres, and sheet-shaped iron porphyrin-based covalent organic framework materials and multi-walled carbon nanotubes loaded on the nano-flower-shaped molybdenum disulfide microspheres; The mass ratio of the sheet-like iron porphyrin-based covalent organic framework material, the nano-flower-like molybdenum disulfide microspheres and the multi-walled carbon nanotubes is 1:(2.8-3):1; The preparation method of the flaky iron porphyrin-based covalent organic framework material comprises the following steps: dispersing the porphyrin-based covalent organic framework material and ferrous sulfate in an organic solvent at a mass ratio of 1:(1.2-1.4), reacting at 18°C-28°C, solid-liquid separation, washing, and drying to obtain the flaky iron porphyrin-based covalent organic framework material; The porphyrin-based covalent organic framework material is prepared by condensation reaction of an aminoporphyrin monomer, a first aldehyde monomer, and a second aldehyde monomer; The aminoporphyrin monomer is 5,10,15,20-tetrakis(4-aminophenyl)-21H,23H-porphyrin; The first aldehyde monomer is 2,4,6-trimethylbenzaldehyde; The second aldehyde monomer is 4,4'-biphenyldicarboxaldehyde.

2. A method for preparing the Fe-pCOFs-MWCNTs / MoS2 nanocomposite material according to claim 1, characterized in that: The method comprises the following preparation steps: Step a, uniformly mixing an aminoporphyrin monomer, a first aldehyde monomer, mesitylene, and acetic acid, adding an alcohol solution of a second aldehyde monomer, mixing uniformly, and reacting at 115° C. to 125° C. to obtain a primary reaction liquid; centrifuging the primary reaction liquid, collecting a supernatant, centrifuging the supernatant, performing solid-liquid separation, washing, and drying to obtain a porphyrin-based covalent organic framework material; Step b, dispersing the porphyrin-based covalent organic framework material and ferrous sulfate in an organic solvent, reacting at 18° C.-28° C., solid-liquid separation, washing, and drying to obtain a sheet-like iron porphyrin-based covalent organic framework material; Step c, dissolving molybdate and thiourea in water, reacting at 195° C.-205° C., solid-liquid separation, washing, and drying to obtain nano-flower-shaped molybdenum disulfide microspheres; Step d: dispersing the sheet-like iron porphyrin-based covalent organic framework material, nano-flower-shaped molybdenum disulfide microspheres and multi-walled carbon nanotubes in water, centrifuging, and drying to obtain the Fe-pCOFs-MWCNTs-MoS2 nanocomposite material.

3. The method for preparing the Fe-pCOFs-MWCNTs / MoS2 nanocomposite material according to claim 2, wherein: In step a, the aminoporphyrin monomer is 5,10,15,20-tetrakis(4-aminophenyl)-21H,23H-porphyrin; and / or In step a, the first aldehyde monomer is 2,4,6-trimethylbenzaldehyde; and / or In step a, the alcohol solution is ethanol; and / or In step a, the second aldehyde monomer is 4,4'-biphenyldicarboxaldehyde; and / or In step a, the molar ratio of the aminoporphyrin monomer, the first aldehyde monomer, mesitylene and acetic acid is 1: (39-41): (348-352): (58-62); and / or In step a, the molar ratio of the aminoporphyrin monomer to the second aldehyde monomer is 1:(2-2.2); and / or In step a, the concentration of the second aldehyde monomer in the alcohol solution is 0.04-0.05 mol / L; and / or In step a, the reaction time is 11h-13h; and / or In step b, the mass ratio of the porphyrin-based covalent organic framework material to ferrous sulfate is 1:(1.2-1.4); and / or In step b, the organic solvent is a mixed solution of dichloromethane and methanol in a volume ratio of 1:(0.8-1.2); and / or In step b, the mass volume ratio of the porphyrin-based covalent organic framework material and the organic solvent is 1g: (0.5-0.7)L; and / or In step b, the reaction time is 32h-38h; and / or In step c, the molybdate is sodium molybdate; and / or In step c, the molar ratio of molybdate to thiourea is 1:(5.8-6.2); and / or In step c, the reaction time is 24h-26h; and / or In step d, the total concentration of the sheet-like iron porphyrin-based covalent organic framework material, nano-flower-shaped molybdenum disulfide microspheres and multi-walled carbon nanotubes in water is 1 mg / mL-1.2 mg / mL.

4. An electrochemical sensor based on an iron porphyrin-based covalent organic framework material, characterized in that: The invention comprises a GCE electrode and the Fe-pCOFs-MWCNTs / MoS2 nanocomposite material according to claim 1 which is wrapped outside the GCE electrode.

5. A method for preparing an electrochemical sensor based on an iron porphyrin-based covalent organic framework material according to claim 4, characterized in that: The method comprises the following preparation steps: Step 1, dispersing the Fe-pCOFs-MWCNTs / MoS2 nanocomposite material in water to obtain a Fe-pCOFs-MWCNTs / MoS2 nanocomposite material dispersion; Step 2: Apply the Fe-pCOFs-MWCNTs / MoS2 nanocomposite dispersion droplets to the surface of the GCE electrode and dry it to obtain an electrochemical sensor based on the iron porphyrin-based covalent organic framework material.

6. The method for preparing an electrochemical sensor based on an iron porphyrin-based covalent organic framework material according to claim 5, wherein: In step 1, the concentration of the Fe-pCOFs-MWCNTs / MoS2 nanocomposite dispersion is 1 mg / mL-1.2 mg / mL.

7. Use of the Fe-pCOFs-MWCNTs / MoS2 nanocomposite material according to claim 1 or the electrochemical sensor based on the iron porphyrin-based covalent organic framework material according to claim 4 in detecting hydrogen peroxide.

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