Preparation method and application of polyaniline nanosheets

Abstract

The present invention relates to a method for preparing polyaniline nanosheets, belonging to the field of conductive polymer preparation. Aniline is added to an aqueous acid solution to form an aniline-acid precipitate. An aqueous ammonium persulfate solution is then added. The mixture is stirred at 0–2°C for 5–10 minutes, then allowed to stand at 0–2°C for 0.5–4 hours. The mixture is subjected to solid-liquid separation, washed, and freeze-dried to obtain the polyaniline nanosheets. During the formation of the polyaniline nanosheets, the aniline-acid precipitate acts as a template.

Description

Technical Field

[0001] The invention belongs to the field of conductive polymer preparation and relates to a method for preparing polyaniline nanosheets. Background Art

[0002] Among conjugated organic polymers, polyaniline has attracted extensive attention due to its ease of preparation, environmental friendliness, unique photoelectric properties, and reversible doping / undoping characteristics ( J. Power Sources 2017, 347 , 86–107; Polymers 2021, 13 , 2003; Inorg. Chem. Commun. 2022, 135 , 109087). According to the literature ( Prog. Polym. Sci. 2010, 35 , 1403–1419), the electrical conductivity of polyaniline films can reach 100 times that of other polyaniline structures. This view has stimulated people's interest in the research of two-dimensional (2D) polyaniline.

[0003] Since the Langmuir-Blodgett technique was used to prepare polyaniline nanofilms in the 1990s ( Thin Solid Films 1996, 288 , 268–271), a variety of methods for preparing 2D polyaniline have been developed, such as the oil / water interface method ( Macromol. Rapid Commun. 2007, 28 , 84–87), template method ( Adv. Mater. 2007, 19 ,2993–2999; Angew. Chem. Int. Ed. 2016, 55 , 12516–12521), using highly oxidized aniline oligomers ( Macromol. Rapid Commun. 2009, 30 , 1577–1582), aniline extremely dilute solution polymerization ( Macromolecules 2007, 40 , 7075–7078; Macromol. Rapid Commun. 2008, 29 , 63–67), electrochemical deposition ( J. Am. Chem. Soc. 1998, 120 , 10733–10742) and ultrasonic stripping ( RSC Adv. 2015, 5 , 48421–48425). However, the above methods have the disadvantages of utilizing (fluorinated) organic reagents, being complex and / or having low yields. Summary of the Invention

[0004] In view of the deficiencies of the prior art, the present invention provides a method for preparing polyaniline nanosheets.

[0005] A method for preparing polyaniline nanosheets is characterized by: using aniline-acid precipitates as templates and chemically oxidizing the aniline-acid precipitates to obtain polyaniline nanosheets.

[0006] A preparation method of polyaniline nanosheets comprises the following steps:

[0007] a. Dissolve the acid in water and add aniline in a stoichiometric ratio to obtain an aniline-acid precipitate;

[0008] b. Mix an aqueous solution of ammonium persulfate (APS) with the aniline-acid precipitate at 0–2 °C, stir for 5–10 minutes, and then allow to stand.

[0009] c. Solid-liquid separation, washing the filter cake with distilled water, and freeze-drying the filter cake to obtain polyaniline nanosheets.

[0010] The acid in step a includes methylene disulfonic acid, sulfuric acid, benzoic acid, oxalic acid and p-toluenesulfonic acid;

[0011] The water in step a is distilled water, and the aniline is redistilled aniline;

[0012] The molar ratio of the acid in step a to aniline is 1:2.

[0013] The APS of step b, wherein the molar ratio of aniline to APS is 4:1-16:1;

[0014] The APS aqueous solution in step b is mixed with the aniline-acid precipitate, wherein the concentration of aniline is 0.24-1.43 mol / L –1 The aniline concentration is the amount of aniline substance divided by the total volume of the reaction system.

[0015] The step b is to allow the mixture to stand for 1–6 h;

[0016] The freeze-drying process in step c is performed under the following conditions: the cold trap temperature is lowered to -80 °C, the sample is placed on the sample rack of the freeze dryer, sealed, and vacuumed to a vacuum gauge reading of 1 Pa, and the process is continued for 4-5 hours.

[0017] The present invention also provides polyaniline nanosheets prepared by the above method. The thickness of the polyaniline nanosheets is 30-170 nm. The specific surface area of ​​the polyaniline nanosheets is 27.6-38.9 m 2 g –1 .

[0018] The XPS N 1s high-resolution spectrum of polyaniline nanosheets has peaks at 398.8, 399.5, 400.5, and 402.2 eV, which correspond to quinone imine (=N–), secondary amine connected to benzene (–NH–), protonated quinone imine (= + NH–) and oxidized secondary amines (– + NH–). The electronic conductivities are 0.50, 0.25, and 0.091 S cm, respectively. -1 .

[0019] The present invention also provides the use of the polyaniline nanosheets prepared by the method, which are used in supercapacitors.

[0020] Beneficial effects

[0021] 1. The present invention provides a method for preparing polyaniline nanosheets, which is simple, environmentally friendly, and easy to scale up for industrial production.

[0022] 2. The present invention provides a method for preparing polyaniline nanosheets, which can regulate the thickness, specific surface area, conductivity, oxidation state and effective conjugation length of the polyaniline nanosheets by controlling the molar ratio of aniline / APS.

[0023] 3. The polyaniline nanosheets provided by the present invention have good electrochemical properties and have potential applications in the field of supercapacitors. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 SEM images of samples S-1, S-2, and S-3: (a, d) S-1; (b, e) S-2; (c, f) S-3.

[0025] Figure 2 Nitrogen adsorption-desorption isotherms of samples S-1, S-2, and S-3.

[0026] Figure 3 Structural characterization of samples S-1, S-2, and S-3: (a) XRD; (b) FT-IR; (c) XPS N 1s.

[0027] Figure 4 SEM images of samples S-4, S-5, S-6, and S-7: (a) S-4; (b) S-5; (c) S-6; (d) S-7.

[0028] Figure 5 SEM images of samples S-8 and S-9: (a) S-8; (b) S-9.

[0029] Figure 6Electrochemical performance of symmetrical flexible supercapacitors of samples S-1‖S-1, S-2‖S-2, and S-3‖S-3: (a) cyclic voltammogram; (b) constant current charge-discharge curve; (c) constant current charge-discharge curve at different curvatures; (d) rate diagram; (e) cycle curve. DETAILED DESCRIPTION

[0030] The technical solution of the present invention will be further described below through specific embodiments in conjunction with the accompanying drawings. These embodiments are only for illustrating the technical solution of the present invention and cannot be regarded as limiting the content of the claims of the present invention.

[0031] Aniline, ammonium persulfate, benzoic acid, oxalic acid, polyvinyl alcohol (PVA), and p-toluenesulfonic acid in the examples were purchased from Shanghai Sinopharm Chemical Reagent Co., Ltd.; methylene disulfonic acid was purchased from Shanghai MacLean Biochemical Technology Co., Ltd.; and sulfuric acid was purchased from Laiyang Fine Chemical Factory.

[0032] X-ray powder diffraction (XRD) spectra were obtained by Bruker D8 Advance powder diffractometer (Germany); scanning electron microscopy (SEM) images and element distribution maps were obtained by Hitachi Regulus8220 field emission scanning electron microscope (Japan); infrared spectra (FT-IR) were obtained by Nicolet 10 infrared spectrometer (USA); X-ray photoelectron spectroscopy (XPS) was obtained by Fisher Scientific ESCALAB Xi + The results were obtained by X-ray photoelectron spectrometer detection; nitrogen adsorption and desorption isotherms and pore size distribution were obtained by the American Autosorb iQ fully automatic specific surface area and pore size analyzer; the sample conductivity was obtained by Guangzhou RTS-9 dual-electrical four-probe tester; the sample was freeze-dried by Xinzhi SCI ENTZ-10N / A-80 degrees Celsius freeze dryer; the electrochemical properties of the sample were obtained by Shanghai Chenhua CHI760E electrochemical analyzer.

[0033] Example 1

[0034] A preparation method of polyaniline nanosheets comprises the following steps:

[0035] a. Dissolve 5 mmol of methylenedisulfonic acid (MDSA) in 3 mL of distilled water and add 10 mmol of freshly distilled aniline to obtain an aniline-MDSA precipitate. Transfer the container containing the aniline-MDSA precipitate to a low-temperature reaction bath and control the temperature of the low-temperature reaction bath to 0–2 °C.

[0036] b. Dissolve 2.5 mmol of APS in 3 mL of distilled water. Mix the APS aqueous solution with the aniline-MDSA precipitate from step a. Stir for 5 minutes and then let stand at 0–2 °C for 0.5 h.

[0037] c. Filter, wash the filter cake with distilled water, and freeze-dry the filter cake to obtain sample S-1.

[0038] Example 2

[0039] A preparation method of polyaniline nanosheets comprises the following steps:

[0040] a. Dissolve 5 mmol of MDSA in 3 mL of distilled water and add 10 mmol of freshly distilled aniline to obtain an aniline-MDSA precipitate. Transfer the container containing the aniline-MDSA precipitate to a low-temperature reaction bath and control the temperature of the low-temperature reaction bath to 0–2 °C.

[0041] b. Dissolve 1.25 mmol of APS in 3 mL of distilled water. Mix the APS aqueous solution with the aniline-MDSA precipitate from step a. Stir for 5 minutes and then let stand at 0–2 °C for 1 hour.

[0042] c. Filter, wash the filter cake with distilled water, and freeze-dry the filter cake to obtain sample S-2.

[0043] Example 3

[0044] A preparation method of polyaniline nanosheets comprises the following steps:

[0045] a. Dissolve 5 mmol of MDSA in 3 mL of distilled water and add 10 mmol of freshly distilled aniline to obtain an aniline-MDSA precipitate. Transfer the container containing the aniline-MDSA precipitate to a low-temperature reaction bath and control the temperature of the low-temperature reaction bath to 0–2 °C.

[0046] b. Dissolve 0.625 mmol of APS in 3 mL of distilled water. Mix the APS aqueous solution with the aniline-MDSA precipitate from step a, stir for 5 minutes, and then let stand at 0–2 °C for 2 hours.

[0047] c. Filter, wash the filter cake with distilled water, and freeze-dry the filter cake to obtain sample S-3.

[0048] Example 4

[0049] A preparation method of polyaniline nanosheets comprises the following steps:

[0050] a. Dissolve 5 mmol of sulfuric acid in 3 mL of distilled water and add 10 mmol of freshly distilled aniline to obtain an aniline-MDSA precipitate. Transfer the container containing the aniline-MDSA precipitate to a low-temperature reaction bath and control the temperature of the low-temperature reaction bath to 0–2 °C.

[0051] b. Dissolve 1.25 mmol of APS in 3 mL of distilled water. Mix the APS aqueous solution with the aniline-MDSA precipitate from step a. Stir for 5 minutes and then let stand at 0–2 °C for 1 hour.

[0052] c. Filter, wash the filter cake with distilled water, and freeze-dry the filter cake to obtain sample S-4.

[0053] Example 5

[0054] A preparation method of polyaniline nanosheets comprises the following steps:

[0055] a. Dissolve 10 mmol of benzoic acid in 3 mL of distilled water and add 10 mmol of freshly distilled aniline to obtain an aniline-MDSA precipitate. Transfer the container containing the aniline-MDSA precipitate to a low-temperature reaction bath and control the low-temperature reaction bath temperature to 0–2 °C.

[0056] b. Dissolve 1.25 mmol of APS in 3 mL of distilled water. Mix the APS aqueous solution with the aniline-MDSA precipitate from step a. Stir for 5 minutes and then let stand at 0–2 °C for 1 hour.

[0057] c. Filter, wash the filter cake with distilled water, and freeze-dry the filter cake to obtain sample S-5.

[0058] Example 6

[0059] A preparation method of polyaniline nanosheets comprises the following steps:

[0060] a. Dissolve 5 mmol of oxalic acid in 4 mL of distilled water and add 10 mmol of freshly distilled aniline to obtain an aniline-MDSA precipitate. Transfer the container containing the aniline-MDSA precipitate to a low-temperature reaction bath and control the temperature of the low-temperature reaction bath to 0–2 °C.

[0061] b. Dissolve 1.25 mmol of APS in 2 mL of distilled water. Mix the APS aqueous solution with the aniline-MDSA precipitate from step a, stir for 5 minutes, and then let stand at 0–2 °C for 4 hours.

[0062] c. Filter, wash the filter cake with distilled water, and freeze-dry the filter cake to obtain sample S-6.

[0063] Example 7

[0064] A preparation method of polyaniline nanosheets comprises the following steps:

[0065] a. Dissolve 10 mmol of p-toluenesulfonic acid in 4 mL of distilled water and add 10 mmol of freshly distilled aniline to obtain an aniline-MDSA precipitate. Transfer the container containing the aniline-MDSA precipitate to a low-temperature reaction bath and control the low-temperature reaction bath temperature to 0–2°C.

[0066] b. Dissolve 1.25 mmol of APS in 2 mL of distilled water. Mix the APS aqueous solution with the aniline-MDSA precipitate from step a, stir for 5 minutes, and then let stand at 0–2 °C for 3 hours.

[0067] c. Filter, wash the filter cake with distilled water, and freeze-dry the filter cake to obtain sample S-7.

[0068] Example 8

[0069] A preparation method of polyaniline nanosheets comprises the following steps:

[0070] a. Dissolve 5 mmol of MDSA in 3 mL of distilled water and add 10 mmol of freshly distilled aniline to obtain an aniline-MDSA precipitate. Transfer the container containing the aniline-MDSA precipitate to a low-temperature reaction bath and control the temperature of the low-temperature reaction bath to 0–2 °C.

[0071] b. Dissolve 1.25 mmol of APS in 39 mL of distilled water. Mix the APS aqueous solution with the aniline-MDSA precipitate from step a, stir for 5 minutes, and then let stand at 0–2 °C for 1.8 hours.

[0072] c. Filter, wash the filter cake with distilled water, and freeze-dry the filter cake to obtain sample S-8.

[0073] Example 9

[0074] A preparation method of polyaniline nanosheets comprises the following steps:

[0075] a. Dissolve 5 mmol of MDSA in 3 mL of distilled water and add 10 mmol of freshly distilled aniline to obtain an aniline-MDSA precipitate. Transfer the container containing the aniline-MDSA precipitate to a low-temperature reaction bath and control the temperature of the low-temperature reaction bath to 0–2 °C.

[0076] b. Dissolve 1.25 mmol of APS in 81 mL of distilled water. Mix the APS aqueous solution with the aniline-MDSA precipitate from step a, stir for 5 minutes, and then let stand at 0–2 °C for 5.5 hours.

[0077] c. Filter, wash the filter cake with distilled water, and freeze-dry the filter cake to obtain sample S-9.

[0078] Example 10

[0079] Assembly of S-1‖S-1 flexible symmetrical supercapacitor

[0080] 1) Take appropriate amount of S-1 powder, acetylene black and polyvinylidene fluoride (mass ratio 8:1:1), transfer them to an agate mortar, and add appropriate amount of N -Methylpyrrolidone, after thorough grinding, to prepare a slurry;

[0081] 2) The slurry was evenly coated on a stainless steel mesh (current collector), and then placed in a vacuum drying oven and dried at 80 °C for 12 h to obtain a working electrode.

[0082] 3) Using PVA / H2SO4 as the electrolyte and paraffin mold as the packaging material, a flexible symmetrical supercapacitor was assembled.

[0083] The preparation method of PVA / H2SO4 electrolyte is as follows: take 5 g of PVA, add it to 50 mL of distilled water, and slowly add 5 mL of concentrated sulfuric acid while stirring; after the addition is completed, heat and stir to 95 °C, keep stirring for 0.5 h, and cool naturally to room temperature.

[0084] Example 11

[0085] Assembly of S-2‖S-2 flexible symmetrical supercapacitor

[0086] The rest is the same as Example 10, except that S-2 powder replaces S-1 powder.

[0087] Example 12

[0088] Assembly of S-3‖S-3 flexible symmetrical supercapacitor

[0089] The rest is the same as Example 10, except that S-2 powder replaces S-1 powder.

[0090] Result Analysis

[0091] During the preparation of samples S-1, S-2, and S-3, the molar ratios of aniline to APS were 4:1, 8:1, and 16:1, respectively. Figure 1 For the SEM images of samples S-1, S-2 and S-3. Figure 1 It can be seen that polyaniline nanosheets are formed in S-1, S-2 and S-3, but S-1 has fibrous nanostructures in addition to polyaniline nanosheets ( Figure 1a). This indicates that increasing the molar ratio of aniline / APS is beneficial to obtaining polyaniline with a single nanosheet morphology. In addition, as the molar ratio of aniline / APS increases from 4:1 to 8:1 and 16:1, the thickness of the polyaniline nanosheet increases from 100–170 nm ( Figure 1 d) gradually decrease to 70–130 ( Figure 1 e) and 30–70 nm ( Figure 1 f). This indicates that the average thickness of polyaniline nanosheets can be regulated by controlling the molar ratio of aniline to APS.

[0092] The different thicknesses of polyaniline nanosheets lead to different specific surface areas of the samples. Figure 2 The nitrogen adsorption-desorption isotherms of samples S-1, S-2, and S-3 are shown. The isotherms are type II adsorption bands with H4 hysteresis loops, indicating that there are mesopores and macropores formed by nanosheet accumulation in the samples. The specific surface areas of S-1, S-2, and S-3 are 27.6, 28.6, and 38.9 m 2 g –1 It can be seen that controlling the molar ratio of aniline / APS can regulate the specific surface area of ​​polyaniline nanosheets.

[0093] The structures and oxidation states of samples S-1, S-2, and S-3 can be revealed by XRD, FT-IR, and XPS analysis. Figure 3 (a) The XRD pattern of the sample shows that the diffraction peaks at 15°, 20°, and 25° are characteristic of acid-doped polyaniline; the latter two peaks are associated with periodicity parallel and perpendicular to the polymer chains, respectively. As the aniline / APS molar ratio increases, a new diffraction peak appears at 6.5°, indicating increased order in the polyaniline structure. This is because the polymerization rate decreases with increasing aniline / APS molar ratio, allowing the polyaniline chains ample time to adjust their conformation. XRD patterns demonstrate that controlling the aniline / APS molar ratio can modulate the structural order of polyaniline nanosheets.

[0094] Figure 3 b is the FT-IR spectrum of samples S-1, S-2 and S-3, where the wavelengths at 1573 and 1496 cm –1 The peaks at 1298 and 1233 cm are attributed to the C=C stretching vibration of the quinone ring and benzene ring in the polyaniline chain; –1 The peaks are attributed to C=N and C–N stretching vibrations; the peaks at 1137 and 1010 cm –1 The peaks are the antisymmetric and symmetric stretching vibration peaks of the O=S=O group. This feature indicates that the use of APS as an oxidant will cause the sulfonate group to be connected to the benzene ring in the polymer chain. –1The peak at 1637 cm and 1414 cm is a characteristic peak of para-substituted aromatic ring, which means the polymerization mechanism of aniline monomers is head-to-tail. It should be noted that there are no peaks at 1637 cm and 1414 cm in the FT-IR spectrum. –1 Peaks related to the phenolazine ring; this result indicates that the formation mechanism of polyaniline nanosheets in the present invention is different from the formation mechanism of polyaniline nanosheets via phenolazine cyclization in a dilute aniline solution (20-22). It is worth noting that with the increase of the aniline / APS molar ratio, the C=C stretching vibration peaks related to the quinone ring and the benzene ring gradually red-shift to 1567 / 1483 and 1560 / 1477 cm –1 This result is attributed to the increase in the effective conjugation length of the polyaniline chain (11). FT-IR results show that the effective conjugation length of the polyaniline chain can be regulated by controlling the molar ratio of aniline to APS.

[0095] Figure 3 c is the XPS N 1s high-resolution spectra of samples S-1, S-2, and S-3. The peaks at 398.8, 399.5, 400.5, and 402.2 eV correspond to quinone imine (=N–), secondary amine connected to benzene (–NH–), protonated quinone imine (= + NH–) and oxidized secondary amines (– + NH–). It is noteworthy that the presence of oxidized nitrogen species decreases with increasing aniline / APS molar ratios; in other words, increasing the amount of APS increases the oxidation level of polyaniline. Considering that the oxidation level of the samples is below 50%, a higher oxidation level indicates a higher conductivity. Four-probe measurement revealed that the electronic conductivities of samples S-1, S-2, and S-3 were 0.50, 0.25, and 0.091 S cm, respectively. -1 The N 1s analysis results show that the oxidation level and conductivity of polyaniline nanosheets can be regulated by controlling the molar ratio of aniline to APS.

[0096] Figure 4 For the SEM images of samples S-4, S-5, S6 and S-7. Figure 4 It can be seen that polyaniline nanosheets can be obtained by chemical oxidative polymerization using the precipitates formed by sulfuric acid, benzoic acid, oxalic acid or p-toluenesulfonic acid and aniline as raw materials. However, since aniline cannot form precipitates with hydrochloric acid or acetic acid, the aniline concentration is 0.24-1.43 mol L ‒1 Under these conditions, polyaniline nanosheets cannot be obtained by chemical oxidation polymerization using APS as an oxidant. Figure 4 The polyaniline nanosheets of samples S-4, S-5, S6 and S-7 have different morphologies, which can be attributed to the different morphologies of the aniline-acid precipitates. Figure 4The results show that any acid that forms a precipitate with aniline can be used to prepare polyaniline nanosheets by forming an aniline-acid precipitate followed by chemical oxidative polymerization, confirming the template role of the aniline-acid precipitate in the formation of polyaniline nanosheets.

[0097] To further confirm the template role of the aniline-acid precipitate in the formation of polyaniline nanosheets, the chemical oxidative polymerization of aniline was investigated at different solvent dosages by increasing the amount of water in the reaction system until the aniline-acid precipitate was completely dissolved. The experimental results showed that when the reaction system volume was increased to 42 mL (the aniline concentration was approximately 0.24 mol L-1), the aniline-MDSA precipitate was the starting material. –1 ), the obtained sample S-8 is still polyaniline nanosheets ( Figure 5 a); Continue to increase the reaction volume to 84 mL (the concentration of aniline is about 0.12 mol L –1 ), since the aniline-MDSA precipitate was completely dissolved and lost its template function, the obtained sample S-9 was not polyaniline nanosheets, but was composed of fibrous and tubular structures ( Figure 5 b). Figure 5 The results disproved the template role of aniline-MDSA precipitate in the formation of polyaniline nanosheets.

[0098] In order to use the polyaniline nanosheets prepared in the present invention for electrochemical energy storage, we used samples S-1, S-2 and S-3 as electrode materials to assemble S-1‖S-1, S-2‖S-2 and S-3‖S-3 symmetrical flexible supercapacitors. Figure 6 a is the three devices at 10 mV s –1 The cyclic voltammogram shows the redox peak corresponding to the redox reaction of polyaniline. –1 Under the conditions of S-1‖S-1, S-2‖S-2 and S-3‖S-3, the discharge specific capacities are 45, 51 and 81 F g, respectively. –1 ( Figure 6 b). Figure 6 The constant current charge-discharge curve in b is not rectangular, and the curved part corresponds to the redox reaction of polyaniline. Taking S-2‖S-2 as an example, the flexibility of the supercapacitor device can be confirmed by the constant current charge-discharge curve under different curvature conditions. Figure 6 c It can be seen that the constant current charge-discharge curve of the device hardly changes as the device is bent at 45°, 90°, and 180°, confirming the flexibility of the device. –1 Under these conditions, S-2‖S-2 exhibits better rate performance than S-3‖S-3 and S-1‖S-1 ( Figure 6d). This indicates that the electrochemical performance of the polyaniline-based supercapacitor depends on the specific surface area of ​​the polyaniline sample, rather than on the oxidation state of the polyaniline sample. –1 After 3500 cycles, S-1‖S-1, S-2‖S-2 and S-3‖S-3 all showed good electrochemical stability ( Figure 6 e); This shows that the polyaniline nanosheets prepared by the present invention have potential application value in the field of supercapacitors.

Claims

1. A method for preparing polyaniline nanosheets, comprising the following steps: a. dissolving the acid in water and adding aniline in a stoichiometric ratio to obtain an aniline - acid precipitate; the acid is one or more of methylene disulfonic acid, sulfuric acid, benzoic acid, oxalic acid and p-toluenesulfonic acid; the molar ratio of the acid to the aniline is 1:2; b. Mix an aqueous ammonium persulfate (APS) solution with the aniline-acid precipitate at 0–2 °C, stir for 5–10 min, and then allow to stand. The molar ratio of aniline to APS is 4:1–16:1, and the concentration of aniline is 0.24–1.43 mol L –1 ; c. Solid-liquid separation, washing the filter cake with distilled water, and freeze-drying the filter cake to obtain polyaniline nanosheets.

2. The method for preparing polyaniline nanosheets according to claim 1, wherein: The mixture is allowed to stand for 1–6 h as described in step b.

3. The polyaniline nanosheet prepared according to the method of claim 1 or 2.

4. The polyaniline nanosheet according to claim 3, wherein: The thickness of polyaniline nanosheets is 30–170 nm; the specific surface area of ​​polyaniline nanosheets is 27.6–38.9 m 2 g –1 .

5. The polyaniline nanosheet according to claim 4, wherein: The XPS N 1s high-resolution spectrum of polyaniline nanosheets has peaks at 398.8, 399.5, 400.5, and 402.2 eV, which correspond to quinone imine (=N–), secondary amine connected to benzene (–NH–), protonated quinone imine (= + NH–) and oxidized secondary amines (– + NH–). The electronic conductivities are 0.50, 0.25, and 0.091 S cm, respectively. -1 .

6. Use of the polyaniline nanosheets prepared by the method according to any one of claims 1 to 2, or use of the polyaniline nanosheets according to any one of claims 3 to 5, in supercapacitors.

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