Preparation method of GDY / G / ITO electrode, EC-NMR device and application
By synthesizing graphene in situ on the ITO electrode and applying graphyyne dropwise, GDY/G/ITO electrodes were prepared, and an in situ EC-NMR device was constructed, which solved the problem of mutual interference between electrochemistry and nuclear magnetic resonance, real-time high-resolution detection of levodopa oxidation reaction and speculation of the reaction mechanism.
Patent Information
- Application Number
- CN202411667007.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-11-21
- Publication Date
- 2025-03-07
AI Technical Summary
There is mutual interference between in-situ electrochemical EC and nuclear magnetic resonance NMR, resulting in a decrease in the resolution and sensitivity of the magnetic field, resulting in problems such as magnetic field inhomogeneity, signal-to-noise ratio decreases and spectral line overlap.
ITO is used as the base electrode, and graphene films are synthesized in situ by laser induction method, and graphyyne is applied driply to it to prepare GDY/G/ITO heterostructure thin film electrodes, and an in situ EC-NMR device is constructed, and only the working electrode is placed in the radio frequency detection area of the nuclear magnetic resonance spectrometer to minimize interference from the electrochemical process on the magnetic field.
Real-time in-situ high-resolution detection of the levodopa oxidation reaction process is achieved, its reaction mechanism is speculated, and the mutual interference between in-situ electrochemistry and nuclear magnetic resonance is avoided to the maximum extent, and the resolution and sensitivity of the magnetic field are improved.
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Figure CN119574665A_ABST
Abstract
Description
Technical Field
[0001] The invention provides a preparation method of a GDY / G / ITO electrode, an EC-NMR device and application thereof, and belongs to the technical field of electrochemistry and nuclear magnetic resonance coupling. Background Art
[0002] The microscopic electrochemical reaction kinetics on the electrode surface cannot be directly revealed by isolated traditional electrochemical methods. Nuclear magnetic resonance technology can provide information such as chemical shift and micro-splitting produced by J coupling of the sample to be tested at the molecular level. It can more easily identify isomers, molecular conformations and electronic changes. Therefore, the in-situ electrochemistry combined with nuclear magnetic resonance technology can conduct in-situ non-destructive real-time research on the reaction mechanism and reaction kinetics of the substance at the molecular level, discover short-lived intermediates that cannot be monitored by non-in-situ technology, and reveal relevant information such as reaction mechanism and structure-activity relationship. It is a very promising in-situ spectroscopic technology. However, due to the introduction of EC cell, there is mutual interference between in-situ electrochemical EC and nuclear magnetic resonance NMR. The magnetic susceptibility and conductivity of the electrode in the electrochemical cell, the electrolysis current, the excessive EC product, and the precipitation generated during the reaction process will reduce the resolution and sensitivity of the magnetic field, resulting in problems such as magnetic field inhomogeneity, decreased signal-to-noise ratio and spectral line overlap. In turn, magnetic field inhomogeneity will also reduce the electrochemical performance of the EC cell. How to reduce the mutual interference between nuclear magnetic resonance (NMR) and EC and develop an EC-NMR combined device suitable for in situ monitoring of the dynamic process of material reactions is a scientific problem that needs to be urgently solved in EC-NMR technology. Summary of the invention
[0003] The purpose of the present invention is to propose a preparation method of a GDY / G / ITO electrode, an EC-NMR device and application, reduce the mutual interference between nuclear magnetic resonance NMR and EC, realize real-time in-situ high-resolution detection of the L-dopa oxidation reaction process, and further infer its reaction mechanism.
[0004] The technical means adopted by the present invention are as follows:
[0005] A method for preparing a GDY / G / ITO electrode comprises the following steps:
[0006] S1, using ITO (an N-type oxide semiconductor - indium tin oxide) as a base electrode, forming a layer of graphene G film on the surface of the ITO electrode by laser induction method to obtain a G / ITO electrode;
[0007] S2. A layer of graphyne GDY film is loaded on the surface of the G / ITO electrode by a drop coating method to obtain a GDY / G / ITO electrode.
[0008] Preferably, the preparation method of the G / ITO electrode in S1 is: brushing polyimide glue on the surface of the ITO substrate electrode, heating at 100° C. in vacuum for 30 min, then heating at 166° C. for 10 min, and finally laser induction.
[0009] Preferably, the mass of polyimide glue used is 2.67 g / cm 2 substrate electrode;
[0010] The vacuum degree of vacuum heating is -0.085~-0.1MPa;
[0011] The laser power of the laser induced is 40 watts x 40%, and the engraving depth is 30.
[0012] Preferably, the specific steps of S2 are: dispersing graphyne in ethanol to obtain graphyne ethanol dispersion; applying droplets of graphyne ethanol dispersion on the G / ITO electrode, and obtaining the GDY / G / ITO electrode after ethanol volatilization.
[0013] Preferably, the concentration of Graphdine in the Graphdine ethanol dispersion is 1.0 mg / mL, and the amount of Graphdine ethanol dispersion dropwise applied is 2 μL / mm 2 G / ITO electrode.
[0014] An EC-NMR device, which is constructed with an electrode prepared according to a preparation method of a GDY / G / ITO electrode as a working electrode, and comprises an in-situ electrochemical cell, in which a working electrode, a reference electrode and a counter electrode are arranged, the working electrode is a G / ITO electrode or a GDY / G / ITO electrode, the reference electrode is a silver wire, and the counter electrode is a platinum wire, and one end of the working electrode, the reference electrode and the counter electrode is inserted into the bottom of the in-situ electrochemical cell;
[0015] The ITO at the other end of the working electrode is connected to the copper wire, and the other ends of the reference electrode and the counter electrode are respectively connected to the copper wire; the bottom of the working electrode is placed in the radio frequency detection area of the nuclear magnetic resonance spectrometer, and the reference electrode and the counter electrode are not located in the radio frequency detection area of the nuclear magnetic resonance spectrometer; the working electrode is located in the radio frequency detection area of the nuclear magnetic resonance spectrometer, and its influence on the magnetic field is very small.
[0016] The three copper wires connected to the working electrode, counter electrode and reference electrode are used to connect the electrochemical cell to the electrochemical workstation through electrical wires.
[0017] Preferably, the in-situ electrochemical cell is a three-electrode single-chamber system, and the in-situ electrochemical cell is a sample tube with a width at the top and a narrowness at the bottom formed by splicing a 5 cm long and 5 mm diameter nuclear magnetic resonance sample tube and a 9 cm long and 10 mm diameter nuclear magnetic resonance sample tube, and a cap is provided at the upper end of the sample tube;
[0018] The connection between ITO and copper wire is coated with conductive epoxy resin, and the surface of copper wire is coated with a layer of polytetrafluoroethylene heat shrink tube;
[0019] The reference electrode and the counter electrode are connected to the copper wire by spot tin welding method, and the welding point and the surface of the copper wire are covered with a layer of polytetrafluoroethylene heat shrink tube. The reference electrode, the working electrode and the counter electrode are arranged side by side in sequence.
[0020] The diameter of the platinum wire is 0.5 mm, and the diameter of the silver wire is 0.5 mm.
[0021] An EC-NMR device is used for real-time in situ monitoring of levodopa oxidation reactions.
[0022] Preferably, the specific steps are: adding a levodopa solution into an in-situ electrochemical cell, placing the bottom of the working electrode in the radio frequency detection area of a nuclear magnetic resonance spectrometer for in-situ sampling, and applying voltage to the electrochemical workstation for collection. The sequence is a standard one-dimensional pulse sequence, and a real-time high-resolution in-situ spectrum is obtained. The levodopa oxidation reaction process is analyzed through the in-situ spectrum.
[0023] Preferably, the concentration of the levodopa solution is 0.01 M, the volume is 50 μL, and the pH is 1;
[0024] The applied voltage of the electrochemical workstation was 900 mV, and the acquisition time was 120 min;
[0025] The nuclear magnetic resonance spectrometer is a 500 MHz nuclear magnetic resonance spectrometer.
[0026] Compared with the prior art, the advantages of the present invention are:
[0027] The present invention uses ITO as a substrate electrode, uses laser induction technology to synthesize a graphene electrode, and loads graphyne on the electrode to construct an in-situ electrochemical cell. In the in-situ electrochemical cell, we only place the GDY / G heterostructure thin film electrode in the nuclear magnetic resonance monitoring area, which has a small impact on the nuclear magnetic resonance magnetic field, and avoids the mutual interference between in-situ electrochemistry and nuclear magnetic resonance to the greatest extent, and can achieve high-resolution in-situ spectra collection of dopamine oxidation reactions in different solutions.
[0028] The present invention uses a laser induction method to synthesize graphene in situ on an ITO electrode, and further drips graphyne on the graphene film to prepare a GDY / G heterostructure thin film electrode, thereby constructing an in-situ EC-NMR device. The in-situ electrochemistry and nuclear magnetic resonance coupling technology are used to conduct real-time research on the oxidation reaction of levodopa, and dynamically monitor the oxidation mechanism of levodopa, providing a basis for the application of in-situ electrochemistry and nuclear magnetic resonance coupling technology in monitoring the reaction mechanism of small drug molecules.
[0029] The specific manifestations are:
[0030] (1) The two nanomaterials used in the GDY / G / ITO heterostructure thin film electrode prepared by the present invention can exert a synergistic effect. The outstanding conductive properties of graphene and its Fermi level higher than the minimum CBM of the conduction band of graphyne make GDY / G have higher catalytic performance. ;
[0031] (2) The present invention directly generates a graphene film in situ on an ITO substrate electrode by a laser induction method, and further directly prepares a GDY / G / ITO heterostructure thin film electrode by a drop coating method, which has the advantages of simple process, low cost, short cycle, and low energy consumption.
[0032] (3) The in-situ EC-NMR device constructed with the GDY / G / ITO heterostructure thin film electrode as the working electrode has little effect on the nuclear magnetic resonance magnetic field, thus avoiding the mutual interference between in-situ electrochemistry and nuclear magnetic resonance to the greatest extent, and can realize high-resolution real-time in-situ spectrum acquisition of dopamine oxidation reaction. BRIEF DESCRIPTION OF THE DRAWINGS
[0033] Figure 1 Schematic diagram of the EC-NMR device structure.
[0034] In the figure, 1-working electrode, 2-reference electrode, 3-counter electrode, 4-cap, 5-conductive epoxy resin, 6-solder, 7-ITO, 8-copper wire, 9-RF detection area, 10-in-situ electrochemical cell, 11-electrochemical workstation.
[0035] Figure 2-1 Scanning electron microscope image of G / ITO electrode
[0036] Figure 2-2 This is a scanning electron microscope image of the GDY / G / ITO electrode.
[0037] Figure 3-1 The one-dimensional images of L-DOPA in the in-situ EC-NMR device and in the conventional 5 mm NMR tube 1 HNMR spectrum.
[0038] Figure 3-2 for Figure 3-1 A partial enlarged view of .
[0039] Figure 4-1 This is the constant potential current-time curve of L-DOPA at 900 mV.
[0040] Figure 4-2 In situ oxidation reaction of L-DOPA at 900 mV 1 H NMR spectrum.
[0041] Figure 4-3 for Figure 4-2 A partial enlarged view of .
[0042] Figure 4-4 for Figure 4-2 A partial enlarged view of .
[0043] Figure 5 This is an enlarged comparison of the spectrum after 120 minutes of in-situ EC-NMR experiment and the spectrum before reaction.
[0044] Figure 6 This is the mechanism diagram of the L-DOPA oxidation reaction when pH = 1. DETAILED DESCRIPTION
[0045] The principles and features of the present invention are described below. The examples given are only used to explain the present invention and are not used to limit the scope of the present invention.
[0046] Example 1
[0047] A uniform layer of polyimide glue (mass 0.08g) was brushed on the ITO surface of 10mm×3mm×1.1mm, and then heated at 100℃ for 30min in a -0.1MPa vacuum drying oven, and then heated at 166℃ for 10min in an oven. The cured PI glue was induced to generate graphene by laser in a laser direct writer. The induction conditions were set to laser power 5.5W X40%, and engraving depth 30, and G / ITO electrode was obtained. The laser direct writer is nano pro 3 laser direct writer produced by Tianjin Jiayin Nano Technology Co., Ltd.
[0048] Accurately weigh 5.0 mg of Graphene and disperse it in 5.0 mL of ethanol to obtain a 1.0 mg / mL Graphene ethanol dispersion. Use a pipette to transfer 60 μL of Graphene ethanol dispersion to the G / ITO electrode. After ethanol evaporates, a GDY / G / ITO heterostructure thin film electrode is obtained. An in-situ EC-NMR device is constructed using GDY / G / ITO.
[0049] Figure 2-2 This is the SEM image of the GDY / G / ITO electrode. Figure 2-1 This is the SEM picture of G / ITO. Figure 2-1 It can be seen that the graphene film generated under laser induction is a porous network structure composed of nanosheets. This structure has a large specific surface area and excellent electrochemical properties, and thus can show high catalytic activity. Figure 2-2 It can be seen that the graphene surface is coated with a layer of graphyne film. Due to the unique few-layer GDY / G heterostructure, the electrode has a larger electrochemically active surface area and faster charge transfer capability, thereby achieving higher catalytic activity.
[0050] Example 2
[0051] An in situ EC-NMR device was constructed using the GDY / G / ITO electrode as the working electrode, e.g. Figure 1 As shown, the in-situ electrochemical cell 10 is a three-electrode single-chamber system, the top of the in-situ electrochemical cell 10 is covered with a cap 4, and the in-situ electrochemical cell 10 is a sample tube with a width at the top and a narrowness at the bottom formed by splicing a nuclear magnetic resonance sample tube with a length of 5 cm and a diameter of 5 mm and an NMR sample tube with a length of 9 cm and a diameter of 10 mm; the working electrode 1 is a G / ITO electrode or a GDY / G / ITO electrode, one end of the ITO 7 is connected to a copper wire 8, and the copper wire 8 is wrapped with a polytetrafluoroethylene (PTFE) heat shrink tube, and the connection is coated with a conductive epoxy resin 5; the reference electrode 2 is a 0.5 mm platinum wire, and the counter electrode 3 is a 0.5 mm platinum wire. .5mm silver wire, the silver wire and the platinum wire are connected to the copper wire 8 by solder 6 respectively, and the welding point and the surface of the copper wire 8 are covered with a layer of PTFE heat shrink tube; the three electrodes are arranged side by side in sequence, only part of the working electrode is placed in the RF detection area 9 of the NMR spectrometer, the counter electrode 3, the working electrode 1 and the reference electrode 2 are fixed by a polytetrafluoroethylene PTFE membrane, and the entire three-electrode system is inserted into the bottom of the spliced sample tube; the working electrode 1, the counter electrode 3 and the reference electrode 2 are respectively led out by the copper wire 8, and then the in-situ electrochemical cell 10 is connected to the electrochemical workstation 11 by an electric wire.
[0052] Verification experiment of the influence of in-situ EC-NMR device on NMR spectrometer
[0053] In order to prove the lower influence of the EC device on the magnetic field, 50 μL of pH=1, 0.01M L-dopa aqueous solution was added to the in-situ electrochemical cell 10 with GDY / G / ITO as the working electrode 1, and the in-situ electrochemical cell 10 was placed in a nuclear magnetic spectrometer for sampling. At the same time, as a comparison, we took 50 μL of pH=1 L-dopa aqueous solution and added it to a conventional 5mm nuclear magnetic tube for sampling. The results are shown in the figure. Figure 3-1 One-dimensional images of L-DOPA in an in-situ electrochemical cell 10 and in a conventional 5 mm NMR tube 1 H NMR spectrum, Figure 3-2 yes Figure 3-1 From the peak height and half-peak width, we can see that the introduction of the in-situ electrochemical cell 10 has almost no effect on the spectrum, further indicating that the GDY / G / ITO electrode has little effect on the magnetic field uniformity and resolution.
[0054] Example 3
[0055] In situ Experimental Monitoring of the Electrochemical Oxidation of Levodopa
[0056] In order to study the electrochemical oxidation process of levodopa (0.01M), in situ EC-NMR coupling technology was used to track its oxidation reaction in real time. Figure 4-1 and Figure 4-2The constant potential current-time curve of L-DOPA at 900mV with GDY / G / ITO as the working electrode and the in situ oxidation reaction at different times are given. 1 H NMR spectrum. In order to observe the changes in the spectrum more clearly, Figure 4-2 The spectrum of Figure 4-3 and Figure 4-4 .from Figure 4-3 and Figure 4-4 It can be seen that the product peaks at 6.82ppm, 6.10ppm and 2.95ppm belonging to dopaquinone appear with the increase of time, and the peak height gradually increases, while the peak height of the reactant gradually decreases. In addition to dopaquinone, no other products were found in the in-situ spectrum. In order to more clearly observe the spectrum after 120 minutes of the in-situ EC-NMR experiment, the spectrum was further enlarged, as shown in the figure below. Figure 5 As shown. Figure 5 We can see that after 120 minutes of reaction, product peaks of dopaquinone appeared at chemical shifts of 6.90ppm, 6.82ppm, 6.65ppm, 6.10ppm and 2.95ppm. In addition, a product peak of cyclized dopa appeared at 6.45ppm, but its peak height was much smaller than the peak height at 6.10ppm belonging to dopaquinone. This shows that in the aqueous solution at pH = 1, most of the electrochemical oxidation product of levodopa, open-ring dopaquinone, was protonated, blocking the cyclization reaction, so there was almost no subsequent reaction. In the aqueous solution at pH = 1, we speculated the possible oxidation mechanism of levodopa at pH 1, such as Figure 6 shown.
[0057] In summary, the present invention uses ITO as the substrate electrode, and sequentially modifies graphene and graphyne on its surface to increase the specific surface area of the electrode and improve its conductivity. An in-situ EC-NMR device with little influence on the nuclear magnetic resonance magnetic field is constructed, and it is successfully applied to the in-situ real-time monitoring of the oxidation reaction of levodopa, and its reaction mechanism is speculated. Figure 6 .
[0058] Due to the synergistic effect of the graphene / graphene GDY / G heterostructure, the composite electrode exhibits good catalytic activity for the oxidation reaction of L-DOPA, and the experiment verifies that its influence on the NMR magnetic field is also very small. The in-situ device can realize high-resolution in-situ real-time monitoring of the oxidation reaction of L-DOPA, providing a basis for the application of in-situ electrochemistry and nuclear magnetic resonance combined technology in monitoring the reaction mechanism of small drug molecules.
[0059] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technical personnel in this field can make some changes or modify the technical contents disclosed above into equivalent embodiments without departing from the scope of the technical solution of the present invention. However, any brief modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.
Claims
1. A method for preparing a GDY / G / ITO electrode, characterized in that: The following steps are involved: S1, using ITO as a base electrode, forming a layer of graphene G film on the surface of the ITO electrode by laser induction method to obtain a G / ITO electrode; S2. A layer of graphyne GDY film is loaded on the surface of the G / ITO electrode by a drop coating method to obtain a GDY / G / ITO electrode.
2. The method for preparing a GDY / G / ITO electrode according to claim 1, characterized in that: The preparation method of G / ITO electrode in S1 is as follows: brush polyimide glue on the surface of ITO substrate electrode, heat at 100°C in vacuum for 30 min, then heat at 166°C for 10 min, and finally induce by laser.
3. The method for preparing a GDY / G / ITO electrode according to claim 2, characterized in that: The mass of polyimide glue is 2.67g / cm 2 substrate electrode; The vacuum degree of vacuum heating is -0.085~-0.1MPa; The laser power of the laser induced is 40 watts x 40%, and the engraving depth is 30.
4. The method for preparing a GDY / G / ITO electrode according to claim 1, characterized in that: The specific steps of S2 are: dispersing graphyne in ethanol to obtain graphyne ethanol dispersion; applying drops of graphyne ethanol dispersion on the G / ITO electrode, and obtaining the GDY / G / ITO electrode after ethanol volatilization.
5. The method for preparing a GDY / G / ITO electrode according to claim 4, characterized in that: The concentration of Graphene in the ethanol dispersion of Graphene is 1.0 mg / mL, and the amount of Graphene ethanol dispersion droplet coating is 2 μL / mm 2 G / ITO electrode.
6. An EC-NMR device, wherein the electrode prepared by the method for preparing a GDY / G / ITO electrode according to any one of claims 1 to 5 is constructed as a working electrode, characterized in that: The invention comprises an in-situ electrochemical cell, in which a working electrode, a reference electrode and a counter electrode are arranged, the working electrode is a G / ITO electrode or a GDY / G / ITO electrode, the reference electrode is a silver wire, the counter electrode is a platinum wire, and one end of the working electrode, the reference electrode and the counter electrode is inserted into the bottom of the in-situ electrochemical cell; The ITO on the other end of the working electrode is connected to the copper wire, and the other ends of the reference electrode and the counter electrode are connected to the copper wire respectively; The bottom of the working electrode is placed in the RF detection area of the NMR spectrometer; The three copper wires connected to the working electrode, counter electrode and reference electrode are used to connect the electrochemical cell to the electrochemical workstation through electrical wires.
7. An EC-NMR device according to claim 6, characterized in that: The in-situ electrochemical cell is a three-electrode single-chamber system, and the in-situ electrochemical cell is a sample tube with a width at the top and a narrowness at the bottom formed by splicing a nuclear magnetic sample tube with a length of 5 cm and a diameter of 5 mm and an NMR sample tube with a length of 9 cm and a diameter of 10 mm, and a cap is provided at the upper end of the sample tube; The connection between ITO and copper wire is coated with conductive epoxy resin, and the surface of copper wire is coated with a layer of polytetrafluoroethylene heat shrink tube; The reference electrode and the counter electrode are connected to the copper wire by spot tin welding method, and the welding point and the surface of the copper wire are covered with a layer of polytetrafluoroethylene heat shrink tube. The reference electrode, the working electrode and the counter electrode are arranged side by side in sequence. The diameter of the platinum wire is 0.5 mm, and the diameter of the silver wire is 0.5 mm.
8. Use of an EC-NMR device according to claim 6, characterized in that: Used for real-time in situ monitoring of L-DOPA oxidation reactions.
9. Use of an EC-NMR device according to claim 8, characterized in that: The specific steps are as follows: add the L-dopa solution into the in-situ electrochemical cell, place the bottom of the working electrode in the radio frequency detection area of the nuclear magnetic resonance spectrometer for in-situ sampling, and apply voltage to the electrochemical workstation for collection. The sequence is a standard one-dimensional pulse sequence to obtain a real-time high-resolution in-situ spectrum, and analyze the L-dopa oxidation reaction process through the in-situ spectrum.
10. Use of an EC-NMR device according to claim 8, characterized in that: The concentration of the L-DOPA solution was 0.01 M, the volume was 50 μL, and the pH was 1; The applied voltage of the electrochemical workstation was 900 mV, and the acquisition time was 120 min; The nuclear magnetic resonance spectrometer is a 500 MHz nuclear magnetic resonance spectrometer.