Preparation method of petal-shaped S, N-co-doped carbon nanosheet loaded with hybrid magnetic nanoparticles as well as product and application of petal-shaped S, N-co-doped carbon nanosheet

Abstract

The invention discloses a preparation method of petal-shaped S, N co-doped carbon nanosheets (HMNPs / S, N-CNSs) loaded with hybrid magnetic nanoparticles as well as a product and application of the petal-shaped S, N co-doped carbon nanosheets. The material is prepared by taking a bimetallic organic framework (MOF) as a precursor through the steps of pyrolysis and vulcanization. The loaded mixed magnetic particles are composed of a large amount of Fe3O4, a part of CoFe alloy and a very small amount of Fe2S. Due to the synergistic effect of the mixed magnetic particles and the S and N co-doped carbon nanosheets, the material shows excellent magnetism, porosity, conductivity and electro-catalytic performance, and shows good catalytic performance on electrochemical reduction of the antibiotic furacilin. HMNPs / S and N-CNSs are modified on the surface of a screen-printed electrode through magnetic control, and the disposable magnetic electrochemical sensor for the furacilin is prepared. The response current signal of the sensor to furacilin is 6.38 times that of a bare electrode, the detection range of the sensor is 0.01-50 [mu] M, and the detection limit is 4.2 nM. The method has the characteristics of low cost, high sensitivity, small detection consumption, good selectivity and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of preparation of novel nanomaterials and electrochemical sensing applications, and specifically provides a petal-shaped S, N co-doped carbon nanosheet (HMNPs / S, N-CNSs) loaded with hybrid magnetic nanoparticles, and a preparation method and application thereof. Background Art

[0002] Metal-organic frameworks (MOFs) have been widely used in energy storage, gas adsorption, electrocatalysis and other fields due to their diverse structures, easy functionalization and high specific surface area. In recent years, MOFs have been used as potential precursors for the synthesis of carbon-based nanomaterials because the organic compounds in MOFs can be converted into carbon in situ by pyrolysis, and even heteroatom-doped carbon. These MOF derivatives inherit the advantages of MOFs and have the characteristics of adjustable defects, variable composition and controllable structure. Studies have shown that MOF-derived heteroatom co-doped porous carbon can enhance oxygen reduction reaction; porous Co3O4 prepared by Co-MOF-74 shows excellent performance as anode material; Fe3C derived from Fe-MOF has significant chromium (VI) adsorption capacity; MOF-converted magnetic metal / carbon nanomaterials have strong absorption capacity for electromagnetic waves and can be well recovered by magnetic separation. In order to improve stability, magnetic particles converted from metal MOFs can be embedded in carbon nanotube networks and carbon nanocages to improve their resistance to the external environment. Therefore, MOF-derived nanomaterials with specific microstructures not only possess good stability but also unexpected properties for various applications.

[0003] Magnetic functional nanomaterials have been widely used as adsorbents and catalysts. Under the action of an external magnetic field, we can effectively control the spatial distribution or interface state of magnetic materials. In addition, magnetic materials can be quickly and effectively regenerated or recovered through magnetic separation. Screen-printed electrodes (SPE) are an alternative to traditional electrodes. They are small in size, powerful in function, highly repeatable, low in cost, maintenance-free, and can achieve on-site and real-time analysis; they can also meet a variety of needs. Therefore, it is used in agriculture, food, environment, clinical and other fields. Combining the advantages of MOF, magnetic materials and SPE, we proposed a magnetic functional composite material prepared with bimetallic MOF as a precursor, and used it as a catalyst to construct a disposable portable furazolidone sensor. Summary of the invention

[0004] The purpose of the present invention is to provide a preparation method of petal-shaped S, N co-doped carbon nanosheets (HMNPs / S, N-CNSs) loaded with hybrid magnetic nanoparticles, as well as a product and application thereof.

[0005] To achieve the above object, the technical solution adopted by the present invention is: a method for preparing petal-shaped S, N-co-doped carbon nanosheets loaded with hybrid magnetic nanoparticles, comprising the following preparation steps:

[0006] (1) Preparation of bimetallic cobalt-iron MOF

[0007] Dissolve appropriate amounts of dry iron metal salt, cobalt metal salt, and 2-methylimidazole in methanol, respectively, and then fully mix the three solutions, stir, stand at room temperature, centrifuge, wash, and dry to obtain a bimetallic MOF precipitate;

[0008] (2) Pyrolysis

[0009] The MOF precursor, sucrose, and dicyandiamide were dispersed in anhydrous ethanol, ultrasonicated, and then placed in an oven for drying. The resulting solid was transferred to a tube furnace for high-temperature pyrolysis under a N2 atmosphere and cooled.

[0010] (3) Vulcanization

[0011] The thiourea and the pyrolysis product were placed in a porcelain boat, calcined under a N2 atmosphere, and slowly cooled to obtain petal-shaped S, N-co-doped carbon nanosheets loaded with hybrid magnetic nanoparticles.

[0012] In step (1), the molar ratio of iron metal salt to cobalt metal salt is 2-4:1, the molar ratio of 2-methylimidazole to metal salt is 4-10:1, the stirring time is 1-4 hours, and the mixture is allowed to stand at room temperature for 15-30 hours.

[0013] In step (2), the mass ratio of sucrose, MOF precursor and dicyandiamide is 1:4-6:10-15, and the heating rate of pyrolysis is 1-4°C·min -1 The pyrolysis temperature is 780-850°C and the pyrolysis time is 1-4 hours.

[0014] In step (3), the mass ratio of thiourea to pyrolysis product is 1:4-8, the calcination temperature is 450-600° C., and the calcination time is 3-6 hours.

[0015] Petal-shaped S, N-co-doped carbon nanosheets loaded with hybrid magnetic nanoparticles prepared according to the method.

[0016] The application of petal-shaped S, N-co-doped carbon nanosheets loaded with hybrid magnetic nanoparticles prepared by the method described in the preparation of disposable furacilin sensors.

[0017] The preparation method of the disposable furacilin sensor comprises the following steps: sticking a strong magnetic waterproof sticker with a comparable diameter to the back of a working electrode of a screen-printed electrode, activating the electrode, dispersing petal-shaped S, N co-doped carbon nanosheets HMNPs / S, N-CNSs loaded with hybrid magnetic nanoparticles in a suitable solvent; dripping a petal-shaped S, N co-doped carbon nanosheets HMNPs / S, N-CNSs dispersion loaded with hybrid magnetic nanoparticles on the surface of the working electrode, finally drying the solvent with filter paper, and adsorbing the petal-shaped S, N co-doped carbon nanosheets HMNPs / N-CNSs loaded with hybrid magnetic nanoparticles on the working electrode through a magnetic sticker.

[0018] The mass concentration of the petal-shaped S, N co-doped carbon nanosheet HMNPs / S, N-CNSs dispersion loaded with hybrid magnetic nanoparticles is 0.5-5.0 mg / mL; the diameter of the working electrode of the screen-printed electrode and the back magnetic sticker is 2-6 mm; the solvent for dispersing the petal-shaped S, N co-doped carbon nanosheet HMNPs / S, N-CNSs loaded with hybrid magnetic nanoparticles is methanol, ethanol, acetone, or N, N-dimethylformamide.

[0019] The disposable magnetic screen-printed electrode is prepared by using the petal-shaped S, N co-doped carbon nanosheets HMNPs / S, N-CNSs loaded with hybrid magnetic nanoparticles.

[0020] In the present invention, petal-shaped S, N co-doped carbon nanosheets (HMNPs / S, N-CNSs) loaded with hybrid magnetic nanoparticles are prepared by high-temperature pyrolysis and sulfurization, and then modified on the working electrode surface of the screen-printed electrode by drop coating as the electrocatalytic sensitive membrane of the sensor. The reduction peak current of the sensor response has a linear correlation with the concentration of furazolidone.

[0021] Compared with the prior art, the innovations and advantages of the present invention include:

[0022] (1) First, bimetallic MOF is used as a precursor to obtain doped magnetic carbon nanosheets. Since the carbon layer on the surface of the carbon sheet is wrapped with magnetic metal-containing nanoparticles, its petal-like special morphology greatly improves the dispersibility of the material.

[0023] (2) Due to S and N doping, abundant defects, mixed magnetic components and sufficient active sites, it has a large specific surface area, excellent electron transfer rate and excellent electrocatalytic performance as a catalyst.

[0024] (3) A disposable magnetic sensor was established by magnetronization method, providing a method for highly sensitive detection of furazolidone. The sensor is easy to prepare and the detection limit can be as low as 4.2nM. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a scanning electron microscope image of the petal-shaped S, N co-doped carbon nanosheet loaded with hybrid magnetic nanoparticles prepared in Example 1.

[0026] Figure 2 This is the XRD pattern of the petal-shaped S, N co-doped carbon nanosheets loaded with hybrid magnetic nanoparticles prepared in Example 1.

[0027] Figure 3 This is the XPS graph of the petal-shaped S, N co-doped carbon nanosheets loaded with hybrid magnetic nanoparticles prepared in Example 1.

[0028] Figure 4 Schematic diagram of the disposable magnetic screen-printed electrode prepared in Example 1.

[0029] Figure 5 Cyclic voltammograms of the disposable magnetic screen-printed electrode and the bare screen-printed electrode (SPE) prepared in Example 1 to furacilin.

[0030] Figure 6 The differential pulse voltammetric response curve (A) of the furacilin sensor prepared in Example 1 at different furacilin concentrations and the linear calibration curve (B) of the peak current and concentration. DETAILED DESCRIPTION

[0031] The following is the preparation of petal-shaped S, N co-doped carbon nanosheets loaded with hybrid magnetic nanoparticles of the present invention and their use in the preparation of disposable magnetic screen-printed electrodes and the detection of furacilin. The following examples are intended to further illustrate the present invention in detail, but not to limit the present invention.

[0032] Example 1

[0033] (1) Preparation of petal-shaped S, N co-doped carbon nanosheets loaded with hybrid magnetic nanoparticles: First, 0.9 mmol of ferric acetate and 0.3 mmol of cobalt nitrate were dissolved in 50 ml of methanol, and 10 mmol of 2-methylimidazole was dissolved in 250 ml of methanol. The two solutions were mixed and gently stirred for 20 min. After being stored at room temperature for 24 h, the bimetallic MOF precursor was obtained by centrifugation, washing, and drying in a 60°C oven. Then, 0.05 g of sucrose, 0.2 g of MOF precursor, and 0.6 g of dicyandiamide were dispersed in 60 ml of anhydrous ethanol, ultrasonicated for 15 min, and then placed in an oven and dried at 60°C for 4 h. The resulting solid was transferred to a tubular furnace and heated at 750°C for 2 h under a N2 atmosphere at a heating rate of 4°C·min -1 Finally, 0.04 g of thiourea and 0.2 g of pyrolysis product were placed at both ends of the porcelain boat and heated at 500 °C at 1 °C min. -1The sulfide product was calcined in a N2 atmosphere at a heating rate of 4 h and cooled. In order to remove unstable metal components, the sulfide product was treated with 0.2 M sulfuric acid at 50 °C for 6 h and washed to neutrality.

[0034] (2) Construction of disposable magnetic screen-printed electrodes: The screen-printed electrode (SPE) uses a carbon circle (d = 5 mm) as the working electrode, a carbon strip as the counter electrode, and a silver / silver chloride strip as the reference electrode. In order to modify the carbon circle, a strong magnetic waterproof sticker with a diameter of 5 mm was pasted on its back. Before modification, the SPE was cleaned by cyclic scanning in a 0.1 M sulfuric acid solution in the potential range of -0.3 to +1.0 V for 6 times and dried in a drying oven at 45°C. HMNPs / S,N-CNSs were ultrasonically dispersed in N,N-dimethylformamide (DMF) to prepare a 1.0 mg / mL dispersion, 8 μL of the dispersion was dripped on the working electrode, and finally the DMF was absorbed with a filter paper strip. HMNPs / S,N-CNSs were thus attached to the carbon circle through the magnetic sticker.

[0035] (3) Determination of furazolidinone: 0.1 mol / L phosphate buffer solution is used as the electrolyte, the pH value is 7.0, the test method is differential pulse voltammetry, and the applied potential range is -0.7 to 0.0 V. The sensor constructed in step (2) is placed in the test solution of standard concentration, and the reduction peak current value of furazolidinone at different concentrations is recorded by differential pulse voltammetry, and a standard curve of current-concentration is drawn. When testing the sample, the measured reduction peak current is compared with the standard curve to calculate the furazolidinone content in the test sample.

[0036] (4) Characterization of the materials obtained in this example and the performance of the sensor: Figure 1 It can be seen that the prepared material has a relatively uniform petal-shaped nanosheet morphology, and many nanoparticles are loaded on its surface. Figure 2 The prepared material has 2θ diffraction characteristic peaks at 30.1°, 35.4°, 43.0°, 53.4°, 57.0° and 62.5°, which correspond to the lattice planes (220), (311), (400), (422), (511), (440) of Fe3O4 magnetite (JCPDS No.99-0073), respectively. In addition, a characteristic peak at 44.7° is the (110) plane of CoFe alloy (JCPDS No.48-1817). It also has two low characteristic peaks at 37.0° and 47.3°, which correspond to the (210) plane and (220) plane of FeS2 (JCPDS No.99-0087). This shows that the prepared magnetic nanomaterial is likely to be composed of a large amount of Fe3O4, part of CoFe alloy and a small amount of Fe2S. Figure 3It was further confirmed that the material was composed of C, N, S, O, Co and Fe elements. By fitting the peaks of each element, it was also proved that Fe3O4, CoFe alloy and Fe2S existed in the prepared magnetic material. Figure 4 The appearance of the disposable magnetic screen-printed electrode is shown. Figure 5 In the experiment, by comparing with bare SPE, it was found that HMNPs / S,N-CNSs greatly enhanced the reduction peak of furazolidone, and its peak current was 6.38 times that of the former. Figure 6 To restore the relationship between the peak current and the concentration of furacilin, the peak current increased with the increase of concentration, the linear detection range was 0.01–50 μM, and the detection limit was 4.2 nM.

[0037] Example 2

[0038] (1) Preparation of petal-shaped S, N co-doped carbon nanosheets loaded with hybrid magnetic nanoparticles: First, 1.6 mmol of ferric nitrate and 0.4 mmol of cobalt nitrate were dissolved in 50 ml of methanol, and 12.0 mmol of 2-methylimidazole was dissolved in 250 ml of methanol. The two solutions were mixed and gently stirred for 20 min. After being stored at room temperature for 24 h, the bimetallic MOF precursor was obtained by centrifugation, washing, and drying in a 60°C oven. Then, 0.05 g of sucrose, 0.3 g of MOF precursor, and 7.0 g of dicyandiamide were dispersed in 60 ml of anhydrous ethanol, ultrasonicated for 15 min, placed in an oven, and dried at 60°C for 4 h. The obtained solid was transferred to a tubular furnace and heated at 800°C for 3 h under a N2 atmosphere at a heating rate of 2°C·min -1 Finally, 0.02 g of thiourea and 0.15 g of pyrolysis product were placed at both ends of the porcelain boat and heated at 550 °C at 1 °C min -1 The sulfide product was calcined in a N2 atmosphere at a heating rate of 3 h and cooled. In order to remove unstable metal components, the sulfide product was treated with 0.2 M sulfuric acid at 50 °C for 6 h and washed to neutrality.

[0039] (2) Construction of disposable magnetic screen-printed electrodes: The screen-printed electrode (SPE) uses a carbon circle (d = 2 mm) as the working electrode, a carbon strip as the counter electrode, and a silver / silver chloride strip as the reference electrode. In order to modify the carbon circle, a strong magnetic waterproof sticker with a diameter of 2 mm is pasted on its back. Before modification, the SPE was cleaned by cyclic scanning in a 0.1 M sulfuric acid solution in the potential range of -0.3 to +1.0 V for 6 times and dried in a drying oven at 45°C. HMNPs / S,N-CNSs were ultrasonically dispersed in anhydrous ethanol to prepare a 0.5 mg / mL dispersion, 8 μL of the dispersion was added to the working electrode, and finally the ethanol solvent was absorbed with a filter paper strip. HMNPs / S,N-CNSs were attached to the carbon circle by a magnetic sticker.

[0040] (3) Determination of Furacilin: Same as Example 1.

[0041] Example 3

[0042] (1) Preparation of petal-shaped S, N co-doped carbon nanosheets loaded with hybrid magnetic nanoparticles: First, 1.0 mmol of ferric chloride and 0.4 mmol of cobalt chloride were dissolved in 40 ml of methanol, and 7.0 mmol of 2-methylimidazole was dissolved in 200 ml of methanol. The two solutions were mixed and gently stirred for 20 min. After being stored at room temperature for 24 h, the bimetallic MOF precursor was obtained by centrifugation, washing, and drying in a 60°C oven. Then, 0.02 g of sucrose, 0.1 g of MOF precursor, and 0.3 g of dicyandiamide were dispersed in 40 ml of anhydrous ethanol, ultrasonicated for 15 min, and then placed in an oven and dried at 60°C for 4 h. The obtained solid was transferred to a tubular furnace and heated at 850°C for 1.5 h under a N2 atmosphere at a heating rate of 4°C·min -1 Finally, 0.05 g of thiourea and 0.4 g of pyrolysis product were placed at both ends of the porcelain boat and heated at 500 °C at 1 °C min. -1 The sulfide product was treated with 0.2 M sulfuric acid at 50 °C for 12 h and washed to neutrality.

[0043] (2) Construction of disposable magnetic screen-printed electrodes: In order to modify the carbon circle part of the screen-printed electrode, a strong magnetic waterproof sticker of equivalent diameter was pasted on its back. Before modification, the SPE was cleaned by cyclic scanning in a 0.1M sulfuric acid solution in the potential range of -0.3 to +1.0V for 6 times and dried in a drying oven at 60°C. HMNPs / S,N-CNSs were ultrasonically dispersed in acetone to prepare a 2.0mg / mL dispersion, 5μL of the dispersion was added to the working electrode, and finally the acetone solvent was absorbed with a filter paper strip. HMNPs / S,N-CNSs were attached to the carbon circle by a magnetic sticker.

[0044] (3) Determination of Furacilin: Same as Example 1.

Claims

1. A method for preparing petal-shaped S, N-co-doped carbon nanosheets loaded with hybrid magnetic nanoparticles, Its characteristics include the following preparation steps: (1) Preparation of bimetallic cobalt-iron MOF Dissolve appropriate amounts of dry iron metal salt, cobalt metal salt, and 2-methylimidazole in methanol, respectively, and then fully mix the three solutions, stir, stand at room temperature, centrifuge, wash, and dry to obtain a bimetallic MOF precipitate; (2) Pyrolysis The MOF precursor, sucrose, and dicyandiamide were dispersed in anhydrous ethanol, ultrasonicated, and then placed in an oven for drying. The resulting solid was transferred to a tube furnace for high-temperature pyrolysis under a N2 atmosphere and cooled. (3) Vulcanization The thiourea and the pyrolysis product were placed in a porcelain boat, calcined under a N2 atmosphere, and slowly cooled to obtain petal-shaped S, N-co-doped carbon nanosheets loaded with hybrid magnetic nanoparticles.

2. The method for preparing petal-shaped S, N-co-doped carbon nanosheets loaded with hybrid magnetic nanoparticles according to claim 1, characterized in that: In step (1), the molar ratio of iron metal salt to cobalt metal salt is 2-4:1, the molar ratio of 2-methylimidazole to metal salt is 4-10:1, the stirring time is 1-4 hours, and the mixture is allowed to stand at room temperature for 15-30 hours.

3. The method for preparing petal-shaped S, N-co-doped carbon nanosheets loaded with hybrid magnetic nanoparticles according to claim 1, characterized in that: In step (2), the mass ratio of sucrose, MOF precursor and dicyandiamide is 1:4-6:10-15, and the heating rate of pyrolysis is 1-4°C·min -1 The pyrolysis temperature is 780-850°C and the pyrolysis time is 1-4 hours.

4. The method for preparing petal-shaped S, N-co-doped carbon nanosheets loaded with hybrid magnetic nanoparticles according to claim 1, characterized in that: In step (3), the mass ratio of thiourea to pyrolysis product is 1:4-8, the calcination temperature is 450-600°C, and the calcination time is 3-6 hours.

5. Petal-shaped S, N-co-doped carbon nanosheets loaded with hybrid magnetic nanoparticles prepared according to the method of claim 1.

6. Use of petal-shaped S, N-co-doped carbon nanosheets loaded with hybrid magnetic nanoparticles prepared by the method of claim 1 in preparing a disposable furacilin sensor.

7. The use according to claim 6, characterized in that the one-time The preparation method of the furazolidone sensor comprises the following steps: sticking a strong magnetic waterproof sticker with a comparable diameter to the back of a working electrode of a screen-printed electrode, activating the electrode, dispersing petal-shaped S, N co-doped carbon nanosheets HMNPs / S, N-CNSs loaded with hybrid magnetic nanoparticles in a suitable solvent; dripping a dispersion of petal-shaped S, N co-doped carbon nanosheets HMNPs / S, N-CNSs loaded with hybrid magnetic nanoparticles on the surface of the working electrode, finally drying the solvent with filter paper, and adsorbing the petal-shaped S, N co-doped carbon nanosheets HMNPs / N-CNSs loaded with hybrid magnetic nanoparticles on the working electrode through a magnetic sticker.

8. The use according to claim 7, characterized in that: The mass concentration of the petal-shaped S, N co-doped carbon nanosheets HMNPs / S, N-CNSs dispersion loaded with hybrid magnetic nanoparticles is 0.5-5.0 mg / mL; the diameter of the working electrode of the screen-printed electrode and the back magnetic sticker is 2-6 mm; the solvent for dispersing the petal-shaped S, N co-doped carbon nanosheets HMNPs / S, N-CNSs loaded with hybrid magnetic nanoparticles is methanol, ethanol, acetone, or N, N-dimethylformamide.

9. The sensing application according to claims 6-8, characterized in that Disposable magnetic screen-printed electrodes were prepared using petal-shaped S, N co-doped carbon nanosheets HMNPs / S,N-CNSs loaded with hybrid magnetic nanoparticles.

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