Preparation method and application of PANI@monolayer graphene / MWCNT material auxiliary electrode

Abstract

This invention belongs to the field of electrokinetic remediation of heavy metals in soil, specifically relating to a method for preparing and applying an auxiliary electrode made of PANI@monolayer graphene oxide / MWCNT material. This invention functionalizes two carbon materials by acid treatment with hydrochloric acid, and then synthesizes polyaniline from aniline and loads it onto the polyaniline to form the auxiliary electrode. The carbon materials are monolayer graphene oxide and MWCNT (multi-walled carbon nanotubes). Under the synergistic effect of the acid-modified monolayer graphene oxide, MWCNT, and PANI, the auxiliary electrode exhibits higher structural stability and superior electrochemical properties, resulting in a longer high-stability time for electrokinetic remediation. The auxiliary electrode prepared using this method has significant advantages in terms of shape and conductivity.

Description

Technical Field

[0001] This invention belongs to the field of electrokinetic remediation technology for heavy metals in soil, specifically relating to a method for preparing and applying an auxiliary electrode made of PANI@monolayer graphene oxide / MWCNT material. Background Technology

[0002] Soil pollution remediation faces challenges such as high difficulty, long processing time, and high costs. Many targeted soil remediation methods have been developed for different types of soil pollution. Electrokinetic remediation (EMR) is a widely used in-situ soil remediation technology. Driven by a voltage gradient, pollutants in the soil are removed through electromigration, electrophoresis, electroosmosis, and diffusion. Electromigration of ionic chemicals caused by the electric field during EMR is a crucial process in pollutant removal. It features simple construction and no secondary pollution in treating contaminated soil, and has been widely used in contaminated soil remediation projects in recent years. To enhance the electric field strength and increase the electrolysis effect during EMR, auxiliary electrodes are currently constructed without direct current, which can strengthen the electric field while reducing energy consumption. Therefore, developing effective auxiliary electrodes is of great significance for achieving soil pollutant removal.

[0003] Current auxiliary electrode materials contain precious metals, such as the carbon nanotube-assisted carbon-coated titanium magnesium phosphate electrode material (patent CN202211202336.7). The main drawbacks of current auxiliary electrode materials include: the high cost and high consumption of precious metals as auxiliary electrodes; the weak electrocatalytic ability and low efficiency of ordinary graphite auxiliary electrodes, affecting usage costs; metal auxiliary electrodes causing metal deposition and electrolyte contamination; and other metal-free auxiliary electrodes suffer from insufficient processing capacity, low current efficiency, and long repair times in electrorepair. Therefore, there is a need to develop a new auxiliary electrode that is less environmentally disruptive, more environmentally friendly, and more economically efficient.

[0004] To address the aforementioned issues, this invention utilizes PANI material, which possesses both semiconductor and conductor properties, to load onto the surface materials of two acid-modified carbon materials (monolayer graphene oxide and MWCNT) to prepare a PANI@monolayer graphene oxide / MWCNT material auxiliary electrode. Summary of the Invention

[0005] To address the need for high-efficiency electrodes in electro-repair processes, this invention prepares a PANI@monolayer graphene oxide / MWCNT material to create an auxiliary electrode that enhances the electro-repair effect.

[0006] The technical solution adopted in this invention is as follows: after acid treatment of monolayer graphene oxide and MWCNTs (multi-walled carbon nanotubes), PANI (polyaniline) synthesized from AN (aniline) is loaded onto the two acid-modified carbon materials. This invention uses monolayer graphene oxide and MWCNTs as the main auxiliary electrode materials. By acid-treating the two carbon materials and then using AN to synthesize PANI for loading, a novel auxiliary electrode is prepared for electrokinetic remediation of pollutants in soil.

[0007] The principle of this invention is as follows: After acid treatment of two carbon materials (monolayer graphene oxide and MWCNTs), the monolayer graphene oxide structure contains various oxygen-containing hydrophilic functional groups such as hydroxyl, carboxyl, and epoxy groups. These functional groups can be modified through chemical reactions, thereby endowing monolayer graphene oxide with new properties. MWCNTs (multi-walled carbon nanotubes) themselves also have many good tube diameters and are loaded with CN, CH, and CO bonds. After acid treatment, they exhibit a well-stable CNT structure and the connection support of oxygen-containing functional groups. Since there is no issue of heavy metal desorption from the electrode surface contaminating the electrolyte, these two carbon materials will have greater application prospects as auxiliary electrode matrix materials than current electrode materials. Polyaniline (PANI) as an electrode material has advantages such as high theoretical specific capacity, good chemical stability, and simple preparation methods. Furthermore, by combining PANI with carbon materials, the problems of poor rate performance and cycle stability of PANI can be effectively compensated. This invention utilizes acid-modified monolayer graphene oxide and MWCNT as the matrix material to support PANI to fabricate an auxiliary electrode, which can significantly improve electrocatalytic performance and electroremediation effect, reduce energy consumption for electroremediation, and enhance the treatment capacity of contaminated soil.

[0008] The preparation method of the PANI@monolayer graphene oxide / MWCNT material auxiliary electrode includes the following steps:

[0009] (1) Preparation of acid-treated monolayer graphene oxide and MWCNT matrix materials: Hydrochloric acid solution and ultrapure water were mixed to prepare HCl aqueous solution; MWCNT material was weighed into a beaker and moistened with a humidifier for 1 min to eliminate static electricity inside the multi-walled carbon nanotube electrode and waited for 60 min; monolayer graphene oxide powder was weighed and added to MWCNT material and mixed; HCl aqueous solution was added and stirred until uniformly mixed; and the mixture was sealed and stirred for 12 h.

[0010] The ratio of MWCNT, monolayer graphene oxide, hydrochloric acid solution (concentration 36-38wt%), and ultrapure water is 6g:0.25-1g:25mL:100mL.

[0011] (2) Preparation of AN solution: Mix hydrochloric acid solution and ultrapure water to prepare HCl aqueous solution; take a certain amount of AN liquid and put it into HCl aqueous solution and shake to obtain AN-HCl solution; wherein, the ratio of MWCNT, AN, hydrochloric acid solution (concentration 36-38wt%) and ultrapure water is 6g:1-2mL:25mL:100mL.

[0012] (3) Slowly add the AN-HCl solution prepared in step (2) into the solution obtained in step (1), and then seal and stir for 12 hours;

[0013] (4) Weigh a certain amount of APS (ammonium persulfate) and dissolve it in ultrapure water to prepare an APS solution; under ice bath conditions (0℃~5℃), drop the APS solution into the solution obtained in step (3) at a dropping rate of 3~5 seconds / drop and a dropping time of 1.75~2.25h, and then stir for 8.75h~9.25h.

[0014] The mass ratio of MWCNT, APS, and ultrapure water is 6:2.28 to 3.42:100.

[0015] (5) The mixed solution obtained in step (4) was filtered and then placed in a vacuum drying oven at a constant temperature of 75°C for 12 hours to obtain PANI@single-layer graphene oxide MWCNT material.

[0016] (6) Preparation of auxiliary electrode material: Weigh the binder (C3H3NaO2). n After being ground through an 80-100 mesh sieve, it is mixed evenly with PANI@monolayer graphene oxide MWCNT material and placed into a die-casting part. Under pressure, it can form a square sheet electrode, in which (C3H3NaO2) is used. n The mass ratio of monolayer MWCNT is 0.8 to 1.2:6; because monolayer graphene oxide and MWCNT have strong compressive strength and are not easily torn, the auxiliary electrode material has extremely strong plasticity.

[0017] As a preferred experimental scheme of the present invention, the resistivity of the ultrapure water is greater than 18 MΩ×cm (25℃).

[0018] Furthermore, in step (1), the MWCNT material needs to be humidified to eliminate static electricity, otherwise it cannot effectively contact the monolayer graphene oxide powder.

[0019] As a preferred experimental scheme of the present invention, in step (1), the ratio of MWCNT: monolayer graphene oxide, hydrochloric acid solution (concentration 36-38wt%), and ultrapure water is 6:0.25:25mL:100mL;

[0020] As a preferred experimental scheme of the present invention, in step (1), the ratio of MWCNT, monolayer graphene oxide, hydrochloric acid solution and ultrapure water is 6g:0.25g:25mL:100mL;

[0021] As a preferred experimental scheme of the present invention, in step (1), the purity of MWCNT material is >99%;

[0022] As a preferred experimental scheme of the present invention, in step (1), the diameter of the single-layer graphene oxide sheet is 0.5-5 μm, the thickness is 0.8-1.2 nm, and the purity is approximately 99%.

[0023] As a preferred experimental scheme of the present invention, in step (2), the ratio of MWCNT, AN, HCl solution (concentration 36-38%) and ultrapure water is 6g:1.17mL:25mL:100mL;

[0024] As a preferred experimental scheme of the present invention, in step (4), the mass ratio of MWCNT, APS and ultrapure water is 6:2.9:100; further, in step (5), the filtration membrane is a 0.45PTFE membrane, and after filtration, it is washed with ultrapure water 3 times before filtration is completed.

[0025] Furthermore, in step (6), (C3H3NaO2) n Average Mw: 3 million to 7 million; sieved after grinding with agate;

[0026] Furthermore, in step (6), an infrared tablet press (pressure value Max = 30 tons) is used to press the tablets, and the mold size is 5cm × 3.5cm × 3cm;

[0027] As a preferred experimental scheme of the present invention, in step (10), the auxiliary electrode material is pressed using a pressure of 27 tons;

[0028] The present invention has the following advantages and technical effects:

[0029] 1. This invention uses acid-modified monolayer graphene oxide and MWCNT as the matrix material to load PANI, and uses this to fabricate a novel auxiliary electrode to solve the problem of limited current and excessive energy loss during the electrokinetic remediation process of soil, which leads to a long electrokinetic remediation process. It enables the electrokinetic remediation current to reach its peak more quickly. The acid-modified monolayer graphene oxide and MWCNT fully introduce defect sites and attach necessary functional groups (such as hydroxyl and carboxyl groups). The PANI loading can fill the voids in the carbon material and form an intricately loaded conductive network. Under the synergistic effect of the acid-modified monolayer graphene oxide, MWCNT, and PANI, the prepared auxiliary electrode exhibits higher structural stability and superior electrochemical characteristics, prolonging the high-stability time (time when the current is greater than 110 mA) experienced during electrokinetic remediation, improving the treatment effect of heavy metal pollution in contaminated soil, and demonstrating comprehensive advantages for treating water containing Cu heavy metal ions, thus enhancing the effectiveness of electrokinetic soil remediation.

[0030] 2. Compared with traditional auxiliary electrodes, such as carbon rods and graphite electrodes, the PANI@monolayer graphene oxide / MWCNT material auxiliary electrode prepared in this invention has a larger specific surface area, which can significantly increase the current and promote the migration of heavy metals in contaminated soil. Because the PANI@monolayer graphene oxide / MWCNT material auxiliary electrode has the characteristics of low preparation cost, good film-forming properties, large specific surface area, and easy functionalization, it avoids the problem of heavy metal desorption from the electrode surface contaminating the electrolyte, and has broad application prospects in the treatment of heavy metal pollution in soil. Attached image description:

[0031] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. The accompanying drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The illustrative embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0032] Figure 1 A photograph of the auxiliary electrode prepared in Example 1, placed in a plastic bag, with dimensions of length: 5cm, width: 3.5cm, and thickness: 0.2cm;

[0033] Figure 2 The figure shows the cyclic voltammetry (CV) curves of the auxiliary electrode prepared in Example 1 in a mixed solution of 0.1 mol / L K3Fe(CN)6 and 0.1 mol / L NaCl, with a saturated calomel electrode as the reference electrode and a silver chloride electrode as the auxiliary electrode.

[0034] Figure 3 The images show X-ray diffraction (XRD) images of the auxiliary electrode materials prepared in Example 1 and Comparative Example 1, with peaks at 2θ = 5° to 80° corresponding to crystalline characteristics. (a) is Example 1, and (b) is Comparative Example 1.

[0035] Figure 4 The image shows the FTIR spectrum of the auxiliary electrode material prepared in Example 1, with the distribution and values ​​of specific peaks marked.

[0036] Figure 5 The image shows a soil electroremediation device, indicating the location of the auxiliary electrode and the size of the device.

[0037] Figure 6 This is a flowchart of the fabrication process for PANI@monolayer graphene oxide MWCNT material. Detailed Implementation

[0038] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of this application, but not all embodiments.

[0039] Based on the embodiments described in this application, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this application. Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. In the event of any conflict with any incorporated literature, the contents of this specification shall prevail.

[0040] Example 1

[0041] a. Weigh 6g of multi-walled carbon nanotubes (MWCNTs) and place them in a 500mL beaker. Use a humidifier to moisten them for 1 minute, and then wait for 60 minutes to eliminate the static electricity inside the MWCNT electrodes. Weigh 0.25g of monolayer graphene oxide and sprinkle it evenly into the beaker and mix it evenly. The mass ratio of MWCNTs to monolayer graphene oxide is 6:0.25.

[0042] b. Weigh 25 mL of hydrochloric acid (HCl concentration 36 wt%) solution and 100 mL of ultrapure water, mix them to prepare an HCl aqueous solution, add it to a beaker containing the MWCNT and monolayer graphene oxide mixture, mix evenly, seal and stir for 12 h to form an acid-modified monolayer graphene oxide and multi-walled carbon nanotube composite solution.

[0043] c. Mix 25 mL of hydrochloric acid (HCl concentration 36 wt%) solution and 100 mL of ultrapure water to prepare an HCl aqueous solution. Add 1.17 mL of aniline (AN) dropwise to the HCl aqueous solution and shake well to obtain an AN-HCl solution.

[0044] d. Weigh 2.9 g of ammonium persulfate (APS), add 100 mL of ultrapure water to dissolve it, and prepare an APS aqueous solution;

[0045] e. Add AN-HCl solution to the acid-modified single-layer graphene oxide and multi-walled carbon nanotube composite solution, place it in a rotor and seal it, then stir for 12 hours until it is evenly mixed.

[0046] f. Transfer the APS aqueous solution to the titration apparatus, which is kept in an ice bath (0℃~5℃). The titration rate is controlled at 3 drops / second. While adding the solution to the mixed solution obtained in step e, magnetic stirring is used. The titration is completed in 2.0h, and then the magnetic stirring time is 9.0h.

[0047] g. After completion, use a vacuum filtration pump to filter through a 0.45 PTFE membrane and then place it in a drying oven. Set the drying oven temperature to 75℃ and dry for 12 hours to obtain PANI@single-layer graphene oxide MWCNT material.

[0048] h. Weigh out the adhesive (C3H3NaO2). n The weight is 0.8g, and it has been ground through an 80-mesh sieve.

[0049] i. Add the ground (C3H3NaO2) n The material was uniformly mixed with PANI@monolayer graphene oxide MWCNT material;

[0050] j. Tableting: A die-casting mold with specifications of 5cm×3.5cm×3cm is used, and an infrared tablet press with 27 tons of pressure is used to make the material into a sheet to produce the auxiliary electrode;

[0051] Comparative Example 1

[0052] The comparative auxiliary electrode 2 was prepared according to the steps of Example 1. The difference between Comparative Example 1 and Example 1 is that the volume of AN added was 0.59 mL, and the rest was the same as Example 1.

[0053] Test case

[0054] The prepared auxiliary electrode was characterized in terms of morphology and electrochemical properties. The test examples of the present invention will be further described in detail below with reference to the accompanying drawings.

[0055] Figure 2The CV curves of the auxiliary electrode material prepared in Example 1 are shown in a 0.1 mol / L K3Fe(CN)6 + 0.1 mol / L NaCl solution. The diameters of the working electrode, reference electrode, and counter electrode (saturated calomel electrode as reference electrode, silver chloride electrode as auxiliary electrode) are 6 mm, 1 mm, and 1 mm, respectively. The CV curves remain closed in the range of -1.0 V to 1.8 V without significant distortion, indicating ideal double-layer capacitance behavior. The material exhibits high ion and electron reversibility and rapid charge transport. Notably, the curves are almost symmetrical with slight distortion, demonstrating excellent redox properties.

[0056] Figure 3 (a) shows the X-ray diffraction (XRD) images of polyaniline prepared in Example 1 loaded on two acid-modified carbon materials. As shown in the figure, no diffraction peaks were observed at 2θ = 11.24° and 35.8°, which indicates that the aniline monomer replaced the original carbon material after acid modification. Figure 3 (b) The comparative auxiliary electrode 2 prepared in Example 2 has an AN content reduced to half that of Example 1. The diffraction peaks in both images mainly appear at 2θ = 12.1° and 25.28°. The diffraction peak at 25.28° is sharper due to the superposition of polyaniline intensities, indicating that polyaniline has a certain degree of crystallinity. However, the amorphous structure of polyaniline usually inhibits its electrochemical performance, resulting in a wider peak shape. Since the AN content of the comparative auxiliary electrode 2 is less than that of the auxiliary electrode of this invention, its peak area is smaller, and the synthesized PANI is insufficient to achieve a greater superposition of crystallinity. Therefore, it can be considered that a good crystal structure is beneficial to the improvement of electrochemical performance.

[0057] Figure 4 The image shows the FTIR spectrum of the auxiliary electrode prepared in Example 1, indicating that the characteristic peak mainly appears at 3429 cm⁻¹. -1 1560cm -1 1489cm -1 1307cm -1 and 1127cm -1 Location: The main components of polyaniline are benzene rings and quinone rings; the tensile vibration of the N-H bond is at 3429 cm⁻¹. -1 1560cm -1 and 1489cm -1 The peak at 1307 cm⁻¹ represents the stretching vibration peak of C=C in the quinone and benzene ring structures. -1 The absorption peak at 1127 cm⁻¹ is generated by the C-N stretching vibration associated with the benzene ring in the diquinone structure of polyaniline; -1 The strong absorption peak at the point is generated by the bending vibration within the C-H bond plane, corresponding to the intrinsic structure. Polyaniline was successfully synthesized on the surface of acid-modified carbon materials.

[0058] Application examples

[0059] Application of auxiliary electrodes in electrodynamic soil remediation:

[0060] (1) Preparation of contaminated soil: After the yellow-brown soil is dug out, it is naturally air-dried for 7 days. Various impurities, plant roots and stems, gravel, etc. are removed. It is then passed through a 20-mesh sieve and water is added daily to stir and make it into a thin mud. After adding CuSO4·5H2O, it is placed in a 150℃ oven for sintering for 24 hours.

[0061] (2) Preparation of aged contaminated soil: The contaminated soil was aged at room temperature for 60 days to obtain aged contaminated soil. The aged contaminated soil was placed in a star ball mill with 700g / part and the speed was adjusted to 3500r / min for 60min. The soil was then ground through a 100-mesh sieve to obtain the prepared aged contaminated soil. The mass of CuSO4·5H2O in the soil was 0.2852g. The purpose was to simulate the environment of electroplating sludge and other heavy metal contaminated soil.

[0062] (3) Place the auxiliary electrode in the soil for soil remediation. Figure 5 The auxiliary electrode was not in contact with the electroremediation device and was not energized. The central soil area was divided into five contaminated zones: S1, S2, S3, S4, and S5. The electroremediation catholyte, anolyte, and electrolyte were all 0.1 mol / L NaCl solutions. Graphite electrodes were used as the cathode and anode. A common graphite auxiliary electrode (comparative auxiliary electrode 1), an auxiliary electrode prepared in Example 2 (comparative auxiliary electrode 2), or an auxiliary electrode prepared in Example 1 were added and placed in the anolyte without energizing. The changes in various parameters during the electroremediation process were tested.

[0063] Table 1 shows the current changes during 7 days of electrorepair process for auxiliary electrodes prepared in Comparative Auxiliary Electrode 1 and Example 1.

[0064] Table 1

[0065]

[0066] Compared with the auxiliary electrode used in Example 1, the ordinary graphite auxiliary electrode enhanced the electroremediation effect by approximately 39% (current > 110 mA time / total time) and showed a slight decrease after remaining stable for 7000 min. Most importantly, the auxiliary electrode of the present invention can make the current climb to the current peak more quickly and the current peak time is longer than other auxiliary electrodes. From the overall electroremediation process, the auxiliary electrode made by the present invention has reliable practical value in enhancing the electroremediation treatment of contaminants.

[0067] Tables 2 and 3 show the distribution of heavy metal Cu(II) in five zones before and after seven days of soil electrokinetic remediation using comparative auxiliary electrode 1, comparative auxiliary electrode 2, and the auxiliary electrode prepared in Example 1.

[0068] The heavy metal content was determined using AAS testing. Approximately 1g of soil-water mixture was taken from 5 zones, diluted 10 times, and hydrochloric acid was added to dissolve Cu ions. The mixture was shaken on a shaker for 6 hours, and then centrifuged at a low speed of 4800r / min for 15 minutes to separate the soil and water. The supernatant was then measured.

[0069] The area of ​​the repair electrode is the same as that of the auxiliary electrode in Example 1, in order to eliminate experimental errors caused by the difference in area.

[0070] Table 2

[0071]

[0072] After electro-repair, the heavy metal content decreased significantly. The processing capacity of the auxiliary electrode prepared in Example 1 was 1.5 to 2.25 times that of the comparative auxiliary electrode 1.

[0073] Table 3

[0074]

[0075]

[0076] After electro-repair, the heavy metal content decreased significantly. From the perspective of each region, the auxiliary electrode of Example 1 had a higher processing efficiency for heavy metal Cu than the comparative auxiliary electrode 2, and the overall effect was better than that of the comparative auxiliary electrode 2.

[0077] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A method for preparing an auxiliary electrode made of PANI@monolayer graphene oxide / MWCNT material, characterized in that, Includes the following steps: (1) Prepare an HCl aqueous solution by mixing hydrochloric acid solution and ultrapure water; weigh out single-layer graphene oxide powder and add it to MWCNT material for mixing, add HCl aqueous solution, mix evenly, seal and stir to form an acid-modified single-layer graphene oxide and multi-walled carbon nanotube composite solution. (2) Mix AN, hydrochloric acid solution and ultrapure water evenly by shaking to obtain AN-HCl solution; slowly add AN-HCl solution to acid-modified single-layer graphene oxide and multi-walled carbon nanotube composite solution and mix evenly, then seal and stir. (3) Dissolve APS in ultrapure water to prepare APS solution; place the solution obtained in step (2) in an ice bath at 0~5℃, add APS solution dropwise while stirring, stir and react for a period of time, filter, dry, and obtain PANI@single-layer graphene oxide MWCNT material; (4) Apply the adhesive (C3H3NaO2) n After grinding and sieving, it is mixed evenly with PANI@monolayer graphene oxide MWCNT material, and then pressed into an electrode to obtain PANI@monolayer graphene oxide MWCNT material auxiliary electrode; Application of the PANI@monolayer graphene oxide / MWCNT material auxiliary electrode in electro-hydraulic soil remediation; The auxiliary electrode is not in contact with the electric repair device and is not energized.

2. The method for preparing the PANI@monolayer graphene oxide / MWCNT material auxiliary electrode according to claim 1, characterized in that, The concentration of the hydrochloric acid solution in step (1) is 36~38 wt%; And / or, the ratio of the amounts of MWCNT, monolayer graphene oxide, hydrochloric acid solution, and ultrapure water is 6g:0.25g~1g:25mL:100mL.

3. The method for preparing the PANI@monolayer graphene oxide / MWCNT material auxiliary electrode according to claim 1, characterized in that, The sealing and stirring time in steps (1) and (2) is 12 hours.

4. The method for preparing the PANI@monolayer graphene oxide / MWCNT material auxiliary electrode according to claim 1, characterized in that, The concentration of the hydrochloric acid solution in step (2) is 36~38 wt%; And / or, the ratio of MWCNT, AN, hydrochloric acid solution, and ultrapure water is 6g:1~2mL:25mL:100mL.

5. The method for preparing the PANI@monolayer graphene oxide / MWCNT material auxiliary electrode according to claim 1, characterized in that, The mass ratio of MWCNT, APS and ultrapure water in step (3) is 6:2.28~3.42:

100.

6. The method for preparing the PANI@monolayer graphene oxide / MWCNT material auxiliary electrode according to claim 1, characterized in that, The dripping time in step (3) is 1.75~2.25h; And / or, the stirring reaction time in step (3) is 8.75h~9.25h.

7. The method for preparing the PANI@monolayer graphene oxide / MWCNT material auxiliary electrode according to claim 1, characterized in that, The mass ratio of MWCNT and (C3H3NaO2)n in step (4) is 6:0.8~1.

2.

8. An auxiliary electrode made of PANI@monolayer graphene oxide / MWCNT material prepared by the method of any one of claims 1-7.

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