Method for preparing composite electrode by depositing gold nanoparticles on graphene, composite electrode and application thereof

Abstract

The present invention discloses a method for preparing a composite electrode by depositing gold nanoparticles on graphene, a composite electrode, and its application, comprising the following steps: S1, laser-induced preparation of a graphene electrode with pins; S2, depositing gold nanoparticles on the graphene electrode to prepare the composite electrode. The present invention combines a laser-induced graphene electrode preparation process with a substrate-assisted deposition process to provide a method for stably, reliably, and simply depositing gold nanoparticles on a laser-induced graphene electrode, thereby preparing a composite electrode that can be used for at least glucose concentration detection. Compared to a bare graphene electrode, the composite electrode prepared in the present invention has significantly lower impedance, a higher redox peak, a significantly larger electrode active area, and better glucose responsiveness.

Description

Technical Field

[0001] The present invention relates to the field of nanomaterials, and in particular to a method for preparing a composite electrode by depositing gold nanoparticles on graphene, the composite electrode and applications thereof. Background Art

[0002] The most common method for preparing metal nanoparticles is the one-pot gold colloid method. This method is complex, requires a large number of raw materials, and requires strict control over the preparation conditions, making it difficult to achieve success. The resulting gold nanoparticles are isolated and cannot be integrated with LIG.

[0003] Substrate-assisted deposition (SAD) is a method similar to a galvanic cell, using a suitable substrate to displace the desired metal ions from the solution onto the working electrode, thereby depositing metal nanoparticles on the working electrode. The paper https: / / doi.org / 10.1016 / j.bios.2018.03.019 ([1]Lin S, Feng W, Miao X, et al. A flexible and highly sensitive nonenzymatic glucose sensor based on DVD-laser scribed graphene substrate [J]. Biosensors & Bioelectronics, 2018: 89. DOI: 10.1016 / j.bios.2018.03.019.) mentions SAD, which assists the deposition of copper nanoparticles on LIG. However, copper is easily oxidized, so gold nanoparticles are more suitable for sensors that require stable manufacturing.

[0004] According to the principle of galvanic cells, copper nanoparticles can be replaced by zinc foil in a copper sulfate solution, but there has been no report on a reliable solution for replacing gold nanoparticles based on the principle of galvanic cells. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to address the deficiencies in the above-mentioned prior art and provide a method for preparing a composite electrode by depositing gold nanoparticles on graphene, a composite electrode and its application.

[0006] To solve the above technical problems, the technical solution adopted by the present invention is to provide a method for preparing a composite electrode by depositing gold nanoparticles on graphene, comprising the following steps:

[0007] S1, laser-induced preparation of graphene electrodes with pins;

[0008] S2. Depositing gold nanoparticles on the graphene electrode to prepare a composite electrode.

[0009] Preferably, step S1 is specifically:

[0010] S1-1. Preparation of processing materials:

[0011] S1-1-1. Take a glass slide, clean it, and cover one side of the glass slide with double-sided tape.

[0012] S1-1-2. Stick the non-adhesive side of the water-soluble adhesive tape on the double-sided tape on the glass sheet until the double-sided tape is fully applied.

[0013] S1-1-3. Tear off the protective layer on the surface of the water-soluble tape to expose the sticky surface;

[0014] S1-1-4, cutting the PI film into the same size as the glass sheet, and then attaching it to the sticky surface of the water-soluble adhesive tape to obtain a processed material;

[0015] S1-2, Electrode processing:

[0016] S1-2-1. Draw the required electrode pattern, reserve pins on the electrode pattern, and import the electrode pattern into the CO2 laser cutting machine;

[0017] S1-2-2. Process the material obtained in step 1) by a carbon dioxide laser cutting machine according to the electrode pattern to obtain a primary product;

[0018] S1-2-3. After processing, tear off a corner of the PI film, drip deionized water from the corner to dissolve the hydrosol tape, then separate the PI film from the glass sheet, discard the glass sheet, and obtain the graphene electrode.

[0019] Preferably, step S2 is specifically:

[0020] S2-1, using copper foil as the substrate, graphene electrode as the modified electrode, and HAuCl4 solution as the replacement solution, the copper foil and the pins of the graphene electrode are connected, and then immersed in HAuCl4 solution for reaction;

[0021] S2-2. After the reaction is completed, the deposited graphene electrode is taken out and rinsed with a deionized solution, the pins are cut off, and then activation is performed to obtain the composite electrode.

[0022] Preferably, step S2-1 is specifically as follows: using copper foil as a substrate, a graphene electrode as a modified electrode, and a HAuCl4 solution as a replacement solution, firstly sticking the graphene electrode to a glass sheet with a flat surface with PI tape, then connecting the copper foil to the pins of the graphene electrode with PI tape, casting and encapsulating the connection position with PDMS, and then immersing it in a HAuCl4 solution and reacting under vacuum for 0.5-2h.

[0023] Preferably, step S2-1 is specifically as follows: using copper foil as the substrate, with an area of 0.1-0.4 cm 2 The graphene electrode was used as the modified electrode, and 30 mL of 0.05-0.2 M HAuCl4 solution was added to the container as the replacement solution. The graphene electrode was first pasted to a glass sheet with a flat surface with PI tape, and then the copper foil was connected to the pins of the graphene electrode with PI tape. The connection position was encapsulated by casting PDMS and then immersed in the HAuCl4 solution in the container. The container was placed in a vacuum box and reacted for 1 hour.

[0024] Preferably, the concentration of the HAuCl4 solution is 0.1 M, and the area of the graphene electrode is 0.2 cm 2 .

[0025] Preferably, the activation method in step S2-2 is: using the deposited graphene electrode in S2-2 as the working electrode of the electrochemical workstation, using a mixed solution of HCl and KCl as the electrode liquid, and scanning 5-50 cycles at a parameter of -0.05V-0.35V.

[0026] Preferably, the activation method in step S2-2 is: using the deposited graphene electrode in S2-2 as the working electrode of the electrochemical workstation, using a mixed solution of 0.1M HCl and 0.1M KCl as the electrode liquid, and scanning 25 times at the parameters of -0.05V-0.35V.

[0027] The present invention also provides a composite electrode, which is prepared by the method described above.

[0028] The present invention also provides an application of the composite electrode described above in glucose concentration detection.

[0029] The beneficial effects of the present invention are:

[0030] The present invention combines a laser-induced graphene electrode preparation process with a substrate-assisted deposition process to provide a stable, reliable, and simple method for depositing gold nanoparticles on a laser-induced graphene electrode, thereby preparing a composite electrode that can be used for at least glucose concentration detection. Compared with a bare graphene electrode, the composite electrode prepared in the present invention has significantly lower impedance, a higher redox peak, a significantly larger electrode active area, and better glucose response.

[0031] Compared with other methods for preparing gold nanoparticles, the substrate-assisted deposition method of gold nanoparticles provided by the present invention is simpler to operate, has lower experimental conditions and a safer experimental environment. In addition, the obtained gold nanoparticles can be stably present on the electrode, and have good application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 Schematic diagram of the process of the method for preparing a composite electrode by depositing gold nanoparticles on graphene according to the present invention;

[0033] Figure 2 Schematic diagram of the principle of gold nanoparticles deposition on the surface of graphene electrode in the present invention;

[0034] Figure 3 This is a SEM image of the composite electrode prepared in Example 1;

[0035] Figure 4 The impedance and redox characteristics analysis results of the electrode;

[0036] Figure 5 is the test result of the electrochemical active area of the electrode;

[0037] Figure 6 This is the sensitivity test result of the electrode for glucose detection. DETAILED DESCRIPTION

[0038] The present invention is further described in detail below with reference to the embodiments so that those skilled in the art can implement the invention with reference to the description.

[0039] It should be understood that terms such as “having”, “including” and “comprising” used herein do not preclude the existence or addition of one or more other elements or combinations thereof.

[0040] Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Materials and reagents used in the following examples are commercially available unless otherwise specified. In the following examples, where specific conditions are not specified, the experiments were conducted under conventional conditions or those recommended by the manufacturer. Reagents and instruments used, where the manufacturer is not specified, are commercially available conventional products.

[0041] Example 1

[0042] Reference Figure 1 This embodiment provides a method for preparing a composite electrode by depositing gold nanoparticles on graphene, comprising the following steps:

[0043] S1. Laser-induced preparation of graphene electrodes with pins:

[0044] S1-1. Preparation of processing materials:

[0045] S1-1-1. Take a 10cm x 10cm glass slide, wash it with deionized water, and tape one side of the glass slide with double-sided tape.

[0046] S1-1-2. Stick the non-adhesive side of the water-soluble adhesive tape on the double-sided tape on the glass until the double-sided tape is fully applied.

[0047] S1-1-3. Tear off the protective layer on the surface of the water-soluble tape to expose the sticky surface;

[0048] S1-1-4. Cut a 0.15 mm thick PI film into the same size as the glass sheet, and then attach it to the sticky surface of the water-soluble adhesive tape. Avoid creating bubbles when attaching, and obtain the processed material.

[0049] The processing materials consist of, from bottom to top, a glass sheet, double-sided tape, water-soluble adhesive tape, and PI film. The glass sheet provides rigid support for the top layer of the PI film; the double-sided tape adheres the glass sheet to the other layers; and the water-soluble adhesive facilitates the peeling of the PI from the rigid substrate. PI is a carbon-containing matrix material that can be formed into graphene through laser processing.

[0050] S1-2, Electrode processing:

[0051] S1-2-1. Draw the required electrode pattern in CAD software, and reserve pins for auxiliary deposition on the electrode pattern. The pins are used to connect the copper foil. After the deposition is completed, the pins can be cut off to avoid damage to the sensor itself; import the electrode pattern into the CO2 laser cutting machine;

[0052] S1-2-2. Process the material obtained in step 1) using a CO2 laser cutter according to the electrode pattern to obtain a primary product. The processing parameters are set to: power 4.5%, speed 5.5%, PPI 1000, and density 6. Under the high temperature of the laser, the carbon-containing bonds in the PI film break, while the instantaneous high pressure causes them to recombine, forming a porous graphene structure. This porous structure facilitates the successful attachment of gold nanoparticles.

[0053] S1-2-3. After processing, tear off a corner of the PI film, drip deionized water from the corner to dissolve the hydrosol tape, then separate the PI film from the glass sheet, discard the glass sheet, and obtain the graphene electrode prepared by laser induction.

[0054] S2. Depositing gold nanoparticles on the graphene electrode to prepare a composite electrode:

[0055] S2-1, using copper foil as the base, with an area of 0.2cm 2The graphene electrode was used as the modified electrode, and 30 mL of 0.1 M HAuCl4 solution was added as the replacement solution to a container with a larger bottom area (the bottom area must be larger than the area of the graphene electrode). The graphene electrode was first pasted to a glass sheet with a flat surface with PI tape, and then the copper foil was connected to the pins of the graphene electrode with PI tape. The connection position was encapsulated with PDMS and then immersed in the HAuCl4 solution in the container. The container was placed in a vacuum box and reacted for 1 hour.

[0056] Observation revealed that gold nanoparticles were not generated in the encapsulated area, but only in the area exposed to the solution. Because PI itself is not strong enough and is relatively light, a glass slide was used to secure the sensor. The graphene electrode was taped to a flat glass slide, ensuring a more even distribution of gold nanoparticles across the graphene electrode.

[0057] S2-2. After the reaction is completed, the deposited graphene electrode is taken out with tweezers and rinsed with deionized solution, the pins are cut off (to avoid affecting the graphene electrode), and then activated to obtain a composite electrode;

[0058] The activation method is as follows: the deposited graphene electrode is used as the working electrode of the electrochemical workstation, a mixed solution of 0.1M HCl and 0.1M KCl is used as the electrode liquid, and the activation is performed at a parameter of -0.05V-0.35V for 25 cycles.

[0059] Common replacement reactions are carried out in solution, and the replaced metal nanoparticles are often deposited at the bottom of the container. The present invention uses a graphene electrode prepared by laser induction as the modified electrode, and the generated gold nanoparticles can be successfully deposited on the surface of the graphene electrode; the formation principle is as follows Figure 2 As shown, in the solution, LIG (graphene electrode) will not be corroded, electrons will gather on the surface of LIG, and free gold ions will encounter electrons on the surface of LIG to become gold nanoparticles, which will then attach to the surface of LIG.

[0060] Example 2

[0061] An application of the composite electrode prepared in Example 1 in glucose concentration detection is as follows: glucose oxidase is first modified on the composite electrode, a sample to be tested is dripped onto the obtained electrode, and then electrochemical signal detection is performed. The glucose concentration in the sample to be tested can be obtained by analysis and calculation.

[0062] In one embodiment, the preparation method of the composite electrode modified with glucose oxidase is as follows (referring to patent CN114609217A graphene film sensor, glucose sensor based thereon and preparation method thereof):

[0063] 1. Prepare Prussian blue solution, chitosan solution and chitosan solution immobilized with glucose oxidase;

[0064] The Prussian blue solution includes 0.01M HCl, 2.5X10 -3 M of FeCl3, 2.5X10 -3 M of K3[Fe(CN)6] and 0.1M KCl.

[0065] The preparation method of the chitosan solution with a mass fraction of 2% is as follows: dissolve chitosan in acetic acid solution according to the weight ratio, stir until the chitosan is fully dissolved, and place it at room temperature until it becomes clear without bubbles to obtain a chitosan solution with a mass fraction of 2%.

[0066] The chitosan solution immobilized with glucose oxidase is prepared by mixing a chitosan solution with a mass fraction of 2% and 34 mg / ml of glucose oxidase in a volume ratio of 1:1.

[0067] 2. The composite electrode of Example 1 was used as the working electrode of an electrochemical workstation, and Ag / AgCl was used as the reference electrode. The composite electrode was placed in a Prussian blue solution and electroplated at a constant voltage of 0.4 V for 60 s, and then dried at room temperature.

[0068] 3. Add the chitosan solution immobilized with glucose oxidase dropwise to the composite electrode dried in step 2. The amount of chitosan solution added is sufficient to form stagnant water droplets on the composite electrode. The electrode is then placed at room temperature for 5-6 hours to obtain a composite electrode modified with glucose oxidase. The detection principle is as follows: hydrogen peroxide is generated by the action of glucose oxidase. This hydrogen peroxide reacts catalyzed by the Prussian blue film to generate water and free electrons. The reaction current is measured to determine the glucose concentration.

[0069] Performance testing and characterization

[0070] 1. Reference Figure 3 A is the SEM image of the composite electrode prepared in Example 1. It can be seen that particles are attached to the surface of graphene, and the scale is nanometer level; Figure 3 B and Figure 3 C is the EDX analysis result of the composite electrode. It can be clearly observed that the distribution and proportion of gold nanoparticles on LIG, and it can be shown that the gold nanoparticles are successfully deposited on the graphene electrode.

[0071] 2. Reference Figure 4 , is the analysis result of the impedance and redox characteristics of the electrode;

[0072] Reference Figure 4A, Electrochemical impedance spectroscopy analysis, in the presence of 5mM [Fe(CN)6] 3- / [Fe(CN)6] 4- The impedance of the bare graphene electrode (LIG) and the graphene electrode deposited with gold nanoparticles (i.e., the composite electrode prepared in Example 1, denoted as LIG / AuNPs) were characterized in a mixed solution of 0.1 M KCl solution. It can be seen that the impedance of LIG / AuNPs is significantly reduced.

[0073] Reference Figure 4 B, in the presence of 5 mM [Fe(CN)6] 3- / [Fe(CN)6] 4- The redox characterization of the electrodes was performed in a mixture of 0.1 M KCl solution and LIG / AuNPs showed that they had a higher redox peak, which was consistent with the impedance change.

[0074] 3. Reference Figure 5 , is the test result of the electrochemical active area of the electrode. The Randles-Sevick method is used to calculate the electrochemical active area of the electrode. Figure 5 A is the electrochemical active area analysis result of bare graphene electrode (LIG), Figure 5 B is the electrochemical active area analysis result of the graphene electrode deposited with gold nanoparticles (i.e., the composite electrode prepared in Example 1, denoted as LIG / AuNPs), Figure 5 C is the calculated result of the electrochemical active area of the two electrodes, according to Figure 5 The results show that the active area of LIG / AuNPs electrode is significantly increased.

[0075] 4. Reference Figure 6 , is the sensitivity test result of the electrode for glucose detection. In this embodiment, the method for modifying glucose oxidase in Example 2 was used to modify glucose oxidase on a bare graphene electrode and a composite electrode prepared in Example 1, respectively, to obtain electrodes that can be used for glucose concentration detection, which were denoted as LIG and LIG / AuNPs respectively; then 0.05 mM glucose was added dropwise to the electrode each time, and then the electrode was used as a working electrode of an electrochemical workstation according to the method in Example 2 to test its response. Figure 6 The results shown indicate that the sensitivity of LIG / AuNPs is more than 2 times that of LIG, showing better glucose responsiveness.

[0076] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the description and implementation methods. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to specific details.

Claims

1. A method for preparing a composite electrode by depositing gold nanoparticles on graphene, characterized in that: The following steps are involved: S1, laser-induced preparation of graphene electrodes with pins; S2, depositing gold nanoparticles on the graphene electrode to prepare a composite electrode; Step S1 is specifically as follows: S1-1. Preparation of processing materials: S1-1-1. Take a glass slide, clean it, and cover one side of the glass slide with double-sided tape. S1-1-2. Stick the non-adhesive side of the water-soluble adhesive tape on the double-sided tape on the glass sheet until the double-sided tape is fully applied. S1-1-3. Tear off the protective layer on the surface of the water-soluble tape to expose the sticky surface; S1-1-4, cutting the PI film into the same size as the glass sheet, and then attaching it to the sticky surface of the water-soluble adhesive tape to obtain a processed material; S1-2, Electrode processing: S1-2-1. Draw the required electrode pattern, reserve pins on the electrode pattern, and import the electrode pattern into the CO2 laser cutting machine; S1-2-2. Process the material obtained in step S1-2-1 using a carbon dioxide laser cutting machine according to the electrode pattern to obtain a primary product; S1-2-3. After processing, tear off a corner of the PI film, drip deionized water from the corner to dissolve the hydrosol tape, and then separate the PI film from the glass sheet, discard the glass sheet, and obtain the graphene electrode; Step S2 is specifically as follows: S2-1, using copper foil as the substrate, with an area of 0.1-0.4cm 2 The graphene electrode was used as the modified electrode, and 30 mL of 0.05-0.2 M HAuCl4 solution was added to the container as the replacement solution. The graphene electrode was first attached to a glass sheet with a flat surface using PI tape. Then, the copper foil was connected to the pins of the graphene electrode using PI tape. The connection position was encapsulated by casting PDMS and then immersed in the HAuCl4 solution in the container. The container was placed in a vacuum box and reacted for 0.5-2 hours. S2-2, after the reaction is completed, the deposited graphene electrode is taken out and rinsed with a deionized solution, the pins are cut off, and then the electrode is activated to obtain the composite electrode; The activation method in step S2-2 is: using the deposited graphene electrode as the working electrode of the electrochemical workstation, using a mixed solution of HCl and KCl as the electrode liquid, and scanning 5-50 cycles at a parameter of -0.05V-0.35V.

2. The method for preparing a composite electrode by depositing gold nanoparticles on graphene according to claim 1, wherein: in, The concentration of HAuCl4 solution is 0.1 M, and the area of the graphene electrode is 0.2 cm 2 .

3. The method for preparing a composite electrode by depositing gold nanoparticles on graphene according to claim 2, wherein: The activation method in step S2-2 is: using the deposited graphene electrode as the working electrode of the electrochemical workstation, using a mixed solution of 0.1M HCl and 0.1M KCl as the electrode liquid, and scanning 25 cycles at a parameter of -0.05V-0.35V.

4. A composite electrode, characterized in that The method is prepared by the method according to any one of claims 1 to 3.

5. Use of the composite electrode according to claim 4 in detecting glucose concentration.

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