Iron-manganese based metal-organic framework composite carbon paper electrode, its preparation method and application

Abstract

This invention discloses an iron-manganese-based metal-organic framework (MOF) composite carbon paper electrode, its preparation method, and its application, relating to the field of MOF electrode preparation technology. This invention prepares a MOF composite carbon paper electrode by in-situ growth of FeMn-MIL-88 on carbon paper. The in-situ growth method strengthens the bonding between the material and the substrate, improving the electrode's stability. FeMn-MIL-88 is prepared via a one-step hydrothermal process and possesses bimetallic catalytic sites, enhancing electrocatalytic activity; the preparation process is simple. The carbon paper improves the conductivity of FeMn-MIL-88 and, when combined with the material, can be directly used as an electrode.

Description

Technical Field

[0001] This invention relates to the field of MOF electrode fabrication technology, and in particular to an iron-manganese based metal-organic framework composite carbon paper electrode, its preparation method, and its application. Background Technology

[0002] Metal-organic frameworks (MOFs) possess the advantages of highly uniform metal catalytic sites, large specific surface area, and tunable structure, making them promising electrode materials for electrocatalysis. However, the weak conductivity of MOFs significantly limits their application in electrochemistry. Fully utilizing the structural advantages of MOFs hinges on overcoming their weak conductivity.

[0003] Currently, a common method to improve the conductivity of MOFs is to composite them with conductive materials such as graphene and carbon nanotubes. After composite formation, the material needs to be modified onto the surface of a bare electrode using a drop-coating method before it can be applied in the electrochemical field. However, electrodes prepared by this method often suffer from problems such as easy material detachment and poor stability, resulting in low catalytic activity and poor sensitivity. Furthermore, how to further enhance the electrocatalytic activity of MOFs is a crucial step in broadening their electrochemical applications. Post-synthetic modification of MOFs is an effective strategy. While this method improves the performance of MOF composites, it involves complex material design, cumbersome synthesis steps, and is time-consuming.

[0004] Based on the above considerations, it is particularly important to design and develop electrodes with high catalytic activity, high conductivity, good stability, and simple preparation process. Summary of the Invention

[0005] To address technical problems such as poor electrode conductivity, easy material detachment, and cumbersome preparation process, this invention provides an iron-manganese-based metal-organic framework composite carbon paper electrode, its preparation method, and its application. The composite carbon paper electrode is obtained by in-situ growth of FeMn-MIL-88 on carbon paper with good conductivity. It has high catalytic activity, high conductivity, and good stability.

[0006] To achieve this technical objective, the present invention adopts the following solution:

[0007] The preparation method of the iron-manganese-based metal-organic framework composite carbon paper electrode includes the following steps:

[0008] S1. Soak the carbon paper in concentrated nitric acid, then soak it in acetone solution to remove surface organic matter, sonicate it in ethanol solution, and rinse it with deionized water.

[0009] S2. Dissolve FeCl3·6H2O and MnCl2·4H2O in N,N-dimethylformamide solution, stir for 15 min at room temperature, and then vertically immerse the carbon paper treated in S1 in the solution.

[0010] S3. Add terephthalic acid to the solution obtained in S2, stir well, and then quickly add NaOH solution while stirring.

[0011] S4. Transfer the solution stirred in S3 to the reaction vessel, seal it, place it in an oven, and carry out a constant temperature reaction. After cooling to room temperature, remove the carbon paper, rinse it with anhydrous ethanol and deionized water to obtain the FeMn-MIL-88 / CP electrode.

[0012] Compared with the prior art, the beneficial effects of the present invention are as follows: The present invention prepares a MOFs composite carbon paper electrode by in-situ growth of FeMn-MIL-88 on carbon paper. The in-situ growth method strengthens the bonding force between the material and the substrate and improves the stability of the electrode. FeMn-MIL-88 is prepared by one-step hydrothermal method and has bimetallic catalytic sites, which improves the electrocatalytic activity and the preparation process is simple. On the one hand, carbon paper improves the conductivity of FeMn-MIL-88, and on the other hand, it can be directly used as an electrode after being combined with the material.

[0013] Furthermore, the S1 carbon paper was soaked in concentrated nitric acid for 24 hours, soaked in acetone for 12 hours, and sonicated for 30 minutes.

[0014] Furthermore, the molar ratio of FeCl3·6H2O to MnCl2·4H2O in S2 is (2~4):1.

[0015] Furthermore, in S2, the stirring time at room temperature is 15 minutes, and the soaking time is 4 hours.

[0016] Furthermore, the amount of terephthalic acid used in S3 is the same as the total molar amount of FeCl3·6H2O and MnCl2·4H2O.

[0017] Furthermore, the sodium hydroxide concentration in S3 was 0.2 mol / L, and the stirring time was 30 min.

[0018] Furthermore, the S4 isothermal reaction temperature is 100℃, and the reaction time is 12–20 h.

[0019] The above preparation method yielded an iron-manganese-based metal-organic framework composite carbon paper electrode. This electrode served as the working electrode, a saturated calomel electrode as the reference electrode, and a platinum sheet electrode as the auxiliary electrode, constructing an electrochemical sensor for the simultaneous detection of dopamine and acetaminophen. This sensor exhibited good electrocatalytic oxidation activity for both dopamine and acetaminophen. Within the concentration range of 0.1–2 μM for dopamine and 0.02–2 μM for acetaminophen, the sensor displayed high detection sensitivity. Attached Figure Description

[0020] Figure 1 A schematic diagram of the FeMn-MIL-88 / CP electrode provided by the present invention;

[0021] Figure 2 The images show the XRD patterns of different modified electrodes provided in Examples 1-5 and Comparative Examples 1-3 of the present invention, wherein (a) is the XRD pattern of Examples 1-3 and Comparative Examples 1-3, and (b) is the XRD pattern of Examples 1 and Examples 4-5.

[0022] Figure 3 SEM images of different modified electrodes provided in Examples 1-5 and Comparative Examples 1-3 of the present invention;

[0023] Figure 4 The CV curves of different modified electrodes provided in Embodiment 1 and Comparative Examples 1 to 3 of the present invention;

[0024] Figure 5 The CV curves of different modified electrodes provided in Examples 1 to 5 of the present invention are shown, wherein (a) is the CV curve of Examples 1 to 3, and (b) is the CV curve of Examples 1, 4, and 5.

[0025] Figure 6 The FeMn-MIL-88 / CP electrode provided in Example 1 of this invention was used to simultaneously measure the DPV curves of dopamine and acetaminophen.

[0026] Figure 7 The linear calibration curve for DPV testing of the FeMn-MIL-88 / CP electrode provided in Embodiment 1 of the present invention. Detailed Implementation

[0027] To fully understand the purpose, features and effects of the present invention, the present invention will be described in detail through the following specific embodiments, but the present invention is not limited thereto.

[0028] like Figure 1As shown, the FeMn-MIL-88 / CP electrode provided by this invention is composed of highly conductive carbon paper and a metal-organic framework of FeMn-MIL-88. The carbon paper is cut into rectangles of 1cm × 1.25cm, and the loading of FeMn-MIL-88 grown in situ on the carbon paper is 28–30 mg / cm². 2 .

[0029] Example 1

[0030] The preparation steps of the FeMn-MIL-88(3:1) / CP electrode are as follows:

[0031] S1. Soak 1cm×1.25cm carbon paper in 18mol / L concentrated nitric acid for 24h, then soak it in 13.5mol / L acetone solution for 12h to remove surface organic matter, and finally sonicate it in ethanol solution for 30min and rinse it with deionized water.

[0032] S2. Dissolve 0.75 mmol FeCl3·6H2O and 0.25 mmol MnCl2·4H2O in 10 mL of N,N-dimethylformamide (DMF) solution, stir for 15 min at room temperature, and then vertically immerse the carbon paper treated in S1 in the solution for 4 h.

[0033] S3. Add 1 mmol of terephthalic acid (PTA) to the solution obtained in S2, stir well, and then quickly add 2 mL of 0.2 mol / L NaOH solution and stir for 30 min.

[0034] S4. Transfer the thoroughly stirred solution from S3 to a Teflon-lined stainless steel autoclave. Seal the autoclave and place it in an oven at 100°C for 12 hours. After cooling to room temperature, remove the carbon paper, rinse it repeatedly with anhydrous ethanol and deionized water, and dry it to obtain FeMn-MIL-88 / CP.

[0035] Example 2

[0036] The preparation of the FeMn-MIL-88(2:1) / CP electrode was the same as that in Example 1, except that in S2, 0.66 mmol FeCl3·6H2O and 0.33 mmol MnCl2·4H2O were dissolved in DMF.

[0037] Example 3

[0038] The preparation of the FeMn-MIL-88(2:1) / CP electrode was the same as that in Example 1, except that in S2, 0.8 mmol FeCl3·6H2O and 0.2 mmol MnCl2·4H2O were dissolved in DMF.

[0039] Comparative Example 1

[0040] The preparation of the blank CP electrode is consistent with the preparation process of S1 in Example 1.

[0041] Comparative Example 2

[0042] The preparation of the Fe-MIL-88 / CP electrode is the same as that in Example 1, except that in S2, only 1 mmol FeCl3·6H2O is dissolved in DMF, and MnCl2·4H2O is not added.

[0043] Comparative Example 3

[0044] The preparation of the Mn-MIL-88 / CP electrode is the same as that in Example 1, except that in S2, only 1 mmol of MnCl2·4H2O is dissolved in DMF, and FeCl3·6H2O is not added.

[0045] Example 4

[0046] The preparation of the FeMn-MIL-88(15h) / CP electrode is the same as that in Example 1, except that in S4, the sealed autoclave is placed in an oven and kept at 100°C for 15h.

[0047] Example 5

[0048] The preparation of the FeMn-MIL-88(20h) / CP electrode is the same as that in Example 1, except that in S4, the sealed autoclave is placed in an oven and kept at 100°C for 20h.

[0049] The modified electrodes prepared in Examples 1-5 and Comparative Examples 1-3 of this invention were characterized as follows:

[0050] Phase analysis of the prepared modified electrodes was performed using a Rigaku D / MAX2500PC X-ray diffractometer (XRD). The X-ray source was Cu Kα (λ = 0.154056 nm). Figure 2 As shown, the strong diffraction peaks at 26.6° and 54.7° are diffraction peaks of the CP matrix. In the XRD patterns of FeMn-MIL-88 / CP, Fe-MIL-88 / CP, and Mn-MIL-88 / CP, not only were diffraction peaks of CP observed, but also weak diffraction peaks of FeMn-MIL-88, Fe-MIL-88, and Mn-MIL-88, indicating that FeMn-MIL-88, Fe-MIL-88, Mn-MIL-88, and CP were successfully composited.

[0051] Morphology analysis of the prepared modified electrodes was performed using a JSM-IT100 scanning electron microscope (SEM), such as... Figure 3As shown, the surface of blank CP is smooth, the particles on the surface of monometallic Fe-MIL-88 / CP are spherical, while the particles on the surface of monometallic Mn-MIL-88 / CP are nanorod-shaped, and the particles on the surface of bimetallic FeMn-MIL-88 / CP are also nanorod-shaped. The nanorod-shaped morphology of FeMn-MIL-88 prepared by different hydrothermal times (12h, 15h, and 20h) and different Fe / Mn ratios (2:1, 3:1, and 4:1) did not change significantly, and the length was about 500 μm.

[0052] The electrocatalytic activity of the modified electrodes prepared in Examples 1-5 and Comparative Examples 1-3 of this invention was studied:

[0053] The present invention provides a FeMn-MIL-88 / CP electrode as the working electrode, a saturated calomel electrode as the reference electrode, and a platinum sheet electrode as the auxiliary electrode to construct an electrochemical sensor for the simultaneous detection of dopamine and acetaminophen.

[0054] The sensing performance of the electrochemical sensor was tested on an electrochemical workstation (CHI660E).

[0055] The catalytic activity of FeMn-MIL-88 / CP for dopamine and acetaminophen was investigated in 0.1M phosphate buffer solution using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) in the potential range of -0.2 to 0.7 V and the scan rate of 0.1 V / s.

[0056] The electrocatalytic oxidation activities of different modified electrodes for dopamine and acetaminophen were investigated using the CV method, such as... Figure 4 As shown, when 100 μM dopamine and acetaminophen were added to 0.1 M phosphate buffer solution, all six modified electrodes exhibited two oxidation peaks (O1 and O2) and one reduction peak (R1) in the potential range of -0.2 to 0.7 V, indicating that the different modified electrodes all exhibited certain electrocatalytic activity towards dopamine and acetaminophen. Different concentrations of Mn 2+ The peak current responses of the regulated FeMn-MIL-88 / CP to dopamine and acetaminophen oxidation were significantly improved compared to those of single-metal Fe-MIL-88 / CP and Mn-MIL-88 / CP, such as... Figure 5 As shown, when the Fe / Mn molar ratio is 3:1 and the hydrothermal time is 12h, FeMn-MIL-88(3:1) / CP exhibits the highest electrocatalytic oxidation activity for dopamine and acetaminophen.

[0057] Taking Example 1 as an example, the electrochemical sensing performance of the FeMn-MIL-88 / CP electrode prepared in this invention for dopamine and acetaminophen was tested.

[0058] The DPV method was used for the simultaneous detection of dopamine and acetaminophen, such as Figure 6 As shown, in 1M phosphate buffer solution, the oxidation peak current response of the FeMn-MIL-88 / CP electrode increases with increasing concentrations of dopamine and acetaminophen. Simultaneously, linear fitting was performed on the DPV curves of dopamine and acetaminophen, as shown... Figure 7 As shown, the peak current of the FeMn-MIL-88 / CP electrode exhibits a good linear relationship in the concentration range of dopamine (0.1–2 μM) and acetaminophen (0.02–2 μM), with sensitivities of 2.85 μA·μM, respectively. -1 ·cm -2 With 7.46 μA·μM -1 ·cm -2 .

[0059] Finally, it should be noted that the above-listed embodiments are merely preferred embodiments of the present invention. Of course, those skilled in the art can make modifications and variations to the present invention. If such modifications and variations fall within the scope of the claims of the present invention and their equivalents, they should be considered as being within the protection scope of the present invention.

Claims

1. Use of an iron-manganese-based metal-organic framework composite carbon paper electrode, characterized in that, The iron-manganese metal organic framework composite carbon paper electrode is used as a working electrode, a saturated calomel electrode is used as a reference electrode, and a platinum sheet electrode is used as an auxiliary electrode to construct an electrochemical sensor for simultaneous detection of dopamine and acetaminophen. The preparation method of the iron-manganese metal organic framework composite carbon paper electrode comprises the following steps: S1, carbon paper is soaked in concentrated nitric acid, then soaked in an acetone solution to remove surface organic matter, and then ultrasonic in an ethanol solution and washed with deionized water; S2, FeCl3·6H2O and MnCl2·4H2O are dissolved in an N, N-dimethylformamide solution, and the carbon paper treated in S1 is vertically placed in the solution and soaked at room temperature for 15 min; S3, terephthalic acid is added to the solution obtained in S2, and then NaOH solution is quickly added and stirred; S4, the solution stirred in S3 is transferred to a reaction kettle, sealed, placed in an oven, and subjected to constant temperature reaction, and then the carbon paper is taken out after being cooled to room temperature, washed with anhydrous ethanol and deionized water to obtain the FeMn-MIL-88 / CP electrode.

2. The use of the iron-manganese-based metal-organic framework composite carbon paper electrode according to claim 1, characterized in that, The carbon paper is soaked in concentrated nitric acid for 24 h, soaked in acetone for 12 h, and ultrasonic for 30 min. 3.The application of the Fe-Mn-based metal-organic framework composite carbon paper electrode according to claim 1, characterized in that, The molar ratio of FeCl3·6H2O to MnCl2·4H2O in S2 is (2-4):

1.

4. The use of the iron-manganese-based metal-organic framework composite carbon paper electrode according to claim 1, characterized in that, The stirring time at room temperature in S2 is 15 min, and the soaking time is 4 h.

5. The use of the iron-manganese-based metal-organic framework composite carbon paper electrode according to claim 1, characterized in that, The amount of terephthalic acid in S3 is the same as the total amount of FeCl3·6H2O and MnCl2·4H2O.

6. The use of the iron-manganese-based metal-organic framework composite carbon paper electrode according to claim 1, characterized in that, The concentration of sodium hydroxide in S3 is 0.2 mol / L, and the stirring time is 30 min.

7. The use of the iron-manganese-based metal-organic framework composite carbon paper electrode according to claim 1, characterized in that, The constant temperature reaction temperature in S4 is 100℃, and the reaction time is 12-20 h.

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