Polyaniline, molybdenum selenide and cellulose nanocrystal composite material and preparation method and application thereof

Abstract

The invention relates to the technical field of composite material preparation, in particular to a polyaniline, molybdenum selenide and cellulose nanocrystal composite material and a preparation method and application thereof. The preparation method of the polyaniline-molybdenum selenide-cellulose nanocrystal composite material comprises the following steps: step 1, adding acrylic acid and a cross-linking agent into a cellulose nanocrystal dispersion liquid to obtain a hydrogel precursor solution; 2, sequentially adding an aniline monomer, a doping agent and an initiator into the hydrogel precursor solution, and carrying out polymerization reaction and first compounding, so as to obtain a first reaction system with a polyaniline-cellulose nanocrystal composite structure; 3, molybdenum selenide nanosheets are added into the first reaction system for second compounding, and a second reaction system of a polyaniline-molybdenum selenide-cellulose nanocrystal composite structure is obtained; 4, the second reaction system is placed in a high-pressure reaction kettle to be subjected to a liquid phase reaction, cooling and washing are conducted, and the polyaniline-molybdenum selenide-cellulose nanocrystalline composite material is obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of composite material preparation, and in particular to a polyaniline@molybdenum selenide@cellulose nanocrystal composite material and a preparation method and application thereof. Background Art

[0002] With the rapid development of energy storage technologies and flexible electronic devices, the demand for composite materials combining high electrochemical performance with excellent mechanical flexibility is becoming increasingly urgent. Polyaniline (PANI), a classic conductive polymer, offers advantages such as tunable conductivity, excellent chemical stability, and low preparation cost. However, its performance is limited by its tendency to agglomerate, small specific surface area, and large volume changes during charge and discharge. Molybdenum selenide (MoSe2), a typical two-dimensional layered transition metal chalcogenide, possesses a unique electronic structure and excellent electrochemical activity, but its conductivity is relatively poor and it tends to agglomerate in solution. Cellulose nanocrystals (CNCs) possess high strength, high modulus, and abundant hydroxyl functional groups, which can significantly enhance the mechanical properties and structural stability of composite materials. However, the combination of PANI, MoSe, and CNCs in a hydrogel matrix to fully exploit the synergistic effect has not been fully explored in the prior art. Existing preparation methods are also complex and suffer from unstable composite performance. Therefore, it is of great significance to develop a simple and efficient preparation method that can significantly improve the overall performance of composite materials. Summary of the Invention

[0003] The purpose of the present invention is to provide a method for preparing a polyaniline@molybdenum selenide@cellulose nanocrystal composite material, which is used to solve the problems of complex preparation process and unstable performance of composite materials used for supercapacitor electrodes in the prior art.

[0004] The present invention also provides a polyaniline@molybdenum selenide@cellulose nanocrystal composite material to solve the problem of poor mechanical properties and structural stability of composite materials used for supercapacitor electrodes in the prior art.

[0005] The present invention also provides an application of a polyaniline@molybdenum selenide@cellulose nanocrystal composite material to solve the problem in the prior art that the composite material has poor electrochemical performance when used in supercapacitor electrodes.

[0006] In order to solve the above problems, the present invention proposes a method for preparing a polyaniline@molybdenum selenide@cellulose nanocrystal composite material, and the technical solution adopted is: Step 1: adding acrylic acid and a cross-linking agent to a cellulose nanocrystal dispersion to obtain a hydrogel precursor solution; Step 2: sequentially adding aniline monomer, dopant and initiator to the hydrogel precursor solution to carry out polymerization reaction and first compounding to obtain a first reaction system having a polyaniline-cellulose nanocrystal composite structure; Step 3, adding molybdenum selenide nanosheets to the first reaction system for a second composite, thereby obtaining a second reaction system having a polyaniline-molybdenum selenide-cellulose nanocrystal composite structure; Step 4: placing the second reaction system in a high-pressure reactor to carry out a liquid-phase reaction, followed by cooling and washing to obtain a polyaniline@molybdenum selenide@cellulose nanocrystal composite material.

[0007] The beneficial effects of the present invention are: (1) The present invention uses a three-component synergistic composite strategy: The present invention is the first to combine polyaniline, molybdenum selenide and cellulose nanocrystals into a three-component composite, fully utilizing the advantages of each component: polyaniline provides high conductivity, molybdenum selenide contributes unique electrochemical activity, and cellulose nanocrystals enhance mechanical properties. The synergistic effect of the three significantly improves the electrochemical performance and structural stability of the composite material.

[0008] (2) Synergistic effect of dopants and cellulose nanocrystals: The initiator triggers the polymerization reaction of aniline monomer to obtain polyaniline; the dopant can improve the conductivity of polyaniline and can also act as a surfactant to effectively prevent the agglomeration of molybdenum selenide; the addition of cellulose nanocrystals forms hydrogen bonds with polyaniline and molybdenum selenide in the hydrogel through the hydroxyl functional groups on their surface, significantly enhancing the structural stability and mechanical properties of the composite material; (3) Innovative combination of step-by-step compounding and high-temperature and high-pressure post-treatment process: The present invention adopts a step-by-step compounding method, firstly polymerizing the aniline monomer under the action of the dopant, initiator, cellulose nanocrystals and hydrogel precursor, and performing the first compounding, then adding molybdenum selenide nanosheets for the second compounding, and finally promoting the interface fusion and structural densification between the components through liquid phase reaction.

[0009] The method for preparing the polyaniline@molybdenum selenide@cellulose nanocrystal composite material of the present invention is simple and efficient, capable of precisely controlling the compounding process of each component and fully leveraging the performance advantages of each component. The composite material prepared by the present invention exhibits high specific capacitance, good rate capability, and structural cycling stability, and has significant application value in the electrochemical application field of supercapacitors. The preparation method of the present invention is simple and easy to operate, requiring no complex equipment or expensive raw materials, and exhibits high production efficiency and low production costs, making it suitable for large-scale industrial production.

[0010] In order to allow the components to fully recombine and undergo polymerization reaction to obtain a polyaniline-cellulose nanocrystal composite structure, preferably, the mass ratio of the acrylic acid to the cellulose nanocrystals in the cellulose nanocrystal dispersion is 1:(1-1.2); and the mass ratio of the aniline monomer to the cellulose nanocrystals in the cellulose nanocrystal dispersion is (1-3):1.

[0011] In order to improve the cross-linking effect of each component, preferably, the cross-linking agent is N,N'-methylenebisacrylamide, and the mass of the N,N'-methylenebisacrylamide is 0.5-1.5% of the mass of acrylic acid.

[0012] In order to enable the dopant to further improve the conductivity of polyaniline and further effectively prevent molybdenum selenide from agglomerating, preferably, the dopant is phytic acid, and the mass ratio of the phytic acid to the aniline monomer is (0.6-0.8):1.

[0013] In order to further initiate the polymerization reaction of the aniline monomer, preferably, the initiator is ammonium persulfate, and the mass ratio of the ammonium persulfate to the aniline monomer is 2.45:1.

[0014] In order to enhance the activity of the polyaniline molecular chain, further promote its close bonding with the surface of the molybdenum selenide nanosheets through chemical bonds and physical adsorption, and further deeply composite with the hydrogel and cellulose nanocrystals, preferably, the added amount of the molybdenum selenide nanosheets is 20-30% of the mass of the aniline monomer.

[0015] In order to further promote the interface fusion and structural densification between the components in a high temperature environment and further improve the performance stability of the composite material, preferably, the temperature of the liquid phase reaction is 80-160° C. and the time is 6-10 hours.

[0016] In order to quickly obtain a cellulose nanocrystal dispersion, preferably, the preparation method of the cellulose nanocrystal dispersion includes: The cellulose nanocrystals are added into deionized water and dispersed by ultrasonication to obtain a uniform cellulose nanocrystal dispersion; The mass ratio of the cellulose nanocrystals to deionized water is 1:(800-1200), the ultrasonic dispersion has a power of 60-100 W, a frequency of 20-30 kHz, and a time of 10-20 min.

[0017] The present invention also proposes a polyaniline@molybdenum selenide@cellulose nanocrystal composite material, the technical solution adopted is: A polyaniline@molybdenum selenide@cellulose nanocrystal composite material is prepared by the above-mentioned preparation method of the polyaniline@molybdenum selenide@cellulose nanocrystal composite material.

[0018] The beneficial effects of the present invention are: the polyaniline@molybdenum selenide@cellulose nanocrystal composite material prepared by the preparation method of the present invention has high specific capacitance, good rate performance and structural cycle stability.

[0019] The present invention also proposes a method for preparing the above-mentioned polyaniline@molybdenum selenide@cellulose nanocrystal composite material to prepare the polyaniline@molybdenum selenide@cellulose nanocrystal composite material or the application of the above-mentioned polyaniline@molybdenum selenide@cellulose nanocrystal composite material in supercapacitor electrodes.

[0020] The beneficial effect of the present invention is that the polyaniline@molybdenum selenide@cellulose nanocrystal composite material of the present invention is applied to supercapacitor electrodes, thereby improving the electrochemical performance of the supercapacitor electrodes. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a SEM image of the polyaniline@molybdenum selenide@cellulose nanocrystal composite material prepared by the preparation method of the polyaniline@molybdenum selenide@cellulose nanocrystal composite material of Example 3 of the present invention.

[0022] Figure 2 This is a charge and discharge curve diagram of the polyaniline@molybdenum selenide@cellulose nanocrystal composite material prepared by the preparation method of the polyaniline@molybdenum selenide@cellulose nanocrystal composite material in Example 3 of the present invention.

[0023] Figure 3 This is a cyclic voltammogram of the polyaniline@molybdenum selenide@cellulose nanocrystal composite material prepared by the preparation method of the polyaniline@molybdenum selenide@cellulose nanocrystal composite material according to Example 3 of the present invention.

[0024] Figure 4 This is an AC impedance test graph of the polyaniline@molybdenum selenide@cellulose nanocrystal composite material prepared by the preparation method of the polyaniline@molybdenum selenide@cellulose nanocrystal composite material according to Example 3 of the present invention. DETAILED DESCRIPTION

[0025] The preparation process of composite materials used for supercapacitor electrodes in the prior art is complex and their performance is unstable. The present invention proposes a method for preparing a polyaniline@molybdenum selenide@cellulose nanocrystal composite material, comprising the following steps: Step 1: adding acrylic acid and a cross-linking agent to a cellulose nanocrystal dispersion to obtain a hydrogel precursor solution; Step 2: sequentially adding aniline monomer, dopant and initiator to the hydrogel precursor solution to carry out polymerization reaction and first compounding to obtain a first reaction system having a polyaniline-cellulose nanocrystal composite structure; Step 3, adding molybdenum selenide nanosheets to the first reaction system for a second composite, thereby obtaining a second reaction system having a polyaniline-molybdenum selenide-cellulose nanocrystal composite structure; Step 4: placing the second reaction system in a high-pressure reactor to carry out a liquid-phase reaction, followed by cooling and washing to obtain a polyaniline@molybdenum selenide@cellulose nanocrystal composite material.

[0026] The technical concept of the present invention is: first, acrylic acid and a cross-linking agent are added to a cellulose nanocrystal dispersion to obtain a hydrogel precursor solution, thereby realizing the preparation of the hydrogel precursor, whose three-dimensional porous network structure provides a fast transmission channel for ions, which is beneficial to improving the electrochemical properties of the composite material, and the cellulose nanocrystals have a reinforcing effect, and their addition can provide an anchor point for aniline polymerization, thereby improving the structural stability of the composite material; secondly, aniline monomer, dopant and initiator are added to the hydrogel precursor solution in sequence to carry out polymerization reaction and first compounding, thereby obtaining a first reaction system having a polyaniline-cellulose nanocrystal composite structure, wherein the initiator initiates the polymerization reaction of the aniline monomer, so that the aniline monomer is gradually polymerized into polyaniline under the joint action of the dopant, cellulose nanocrystals and hydrogel precursor, and preliminarily combines with the cellulose nanocrystals. The method comprises the following steps: the first reaction system is added with molybdenum selenide nanosheets to form a composite structure; the dopant improves the conductivity of polyaniline and can also serve as a surfactant to prevent the subsequently added molybdenum selenide from agglomerating; the molybdenum selenide nanosheets are then added to the first reaction system for a second composite, thereby obtaining a second reaction system having a polyaniline-molybdenum selenide-cellulose nanocrystal composite structure, wherein the molybdenum selenide nanosheets have catalytic properties. After the addition of the molybdenum selenide nanosheets, the activity of the polyaniline molecular chain is enhanced, and the polyaniline can be tightly combined with the surface of the molybdenum selenide nanosheets through chemical bonds and physical adsorption, and further deeply composited with the cellulose nanocrystals; finally, the second reaction system is placed in a high-pressure reactor for a liquid-phase reaction, which can promote the interface fusion and structural densification between the components, further improving the performance stability of the composite material, and obtaining a polyaniline@molybdenum selenide@cellulose nanocrystal composite material after cooling and washing.

[0027] The present invention's method for preparing a polyaniline, molybdenum selenide, and cellulose nanocrystal composite material achieves deep integration of a conductive polymer and two-dimensional nanosheets through molecular-level interface engineering, and utilizes the hydrogen bonding network of a biomass reinforcing agent to construct a three-dimensional conductive architecture. This breakthrough utilizes a micro-doping strategy to achieve efficient polyaniline doping and uniform dispersion of molybdenum selenide. Simultaneously, the three-dimensional interconnected structure optimizes charge transfer pathways, significantly reducing raw material costs while developing a novel electrochemical material system that combines high specific capacitance with excellent structural stability, providing an innovative solution for flexible energy storage devices.

[0028] Specifically, the preparation method of the polyaniline@molybdenum selenide@cellulose nanocrystal composite material comprises the following steps: (1) Pre-dispersion of cellulose nanocrystals: Add cellulose nanocrystals to deionized water and ultrasonically disperse for a period of time to obtain a uniform cellulose nanocrystal dispersion; wherein the mass ratio of cellulose nanocrystals to deionized water is 1:(800-1200), the ultrasonic dispersion power is 60-100 W, the frequency is 20-30 kHz, and the time is 10-20 min; (2) Preparation and mixing of hydrogel precursor: Acrylic acid (AA) and crosslinking agent N,N'-methylenebisacrylamide (MBA) are added to the above-mentioned cellulose nanocrystal dispersion and stirred to form a hydrogel precursor solution; wherein the mass ratio of acrylic acid to cellulose nanocrystals in the cellulose nanocrystal dispersion is 1:(1-1.2); the mass of N,N'-methylenebisacrylamide is 0.5-1.5% of the mass of acrylic acid; (3) Pre-dispersion of aniline monomer and introduction of dopant: Aniline monomer was added to the above hydrogel precursor solution and stirred at room temperature at a speed of 200-400 rpm for 10-20 min to fully disperse it; then, phytic acid was slowly added as a dopant and stirred for 20-40 min to obtain a mixed solution; wherein the mass ratio of aniline monomer to cellulose nanocrystals in the cellulose nanocrystal dispersion was (1-3):1; the mass ratio of phytic acid to aniline monomer was (0.6-0.8):1; (4) Addition of initiator and preliminary polymerization: Ammonium persulfate (APS) was slowly added to the above mixed solution as an initiator to initiate the polymerization reaction of aniline monomer; the mixture was then stirred in an ice-water bath for a period of time, so that the aniline monomer was gradually polymerized into polyaniline under the combined action of phytic acid doping, cellulose nanocrystals and hydrogel precursors, and initially formed a composite structure with cellulose nanocrystals, thereby obtaining a first reaction system having a polyaniline-cellulose nanocrystal composite structure; wherein the mass ratio of ammonium persulfate to aniline monomer was 2.45:1; (5) Deep compounding of MoSe nanosheets: MoSe nanosheets that have been subjected to ultrasonic dispersion treatment are added to the first reaction system, and the stirring reaction is continued for 3-5 hours to perform the second compounding; polyaniline is tightly combined with the surface of MoSe nanosheets through chemical bonds and physical adsorption, and further deeply compounded with cellulose nanocrystals for 3-5 hours to obtain a second reaction system having a composite structure of polyaniline-MoSe-cellulose nanocrystals; wherein the amount of MoSe nanosheets added is 20-30% of the mass of the aniline monomer; (6) Liquid phase reaction and post-treatment: The second reaction system was transferred to a high-pressure reactor and the liquid phase reaction was carried out at a temperature of 80-160 °C for 6-10 h. After the reaction, the product was cooled to room temperature and washed with deionized water and anhydrous ethanol several times to remove unreacted aniline monomer, initiator and other impurities to obtain a polyaniline@molybdenum selenide@cellulose nanocrystal composite material.

[0029] Specifically, during the addition of the initiator and the preliminary polymerization, the stirring speed is 400-600 rpm and the time is 5-7 hours.

[0030] In the deep composite of MoSe nanosheets, the power of ultrasonic dispersion treatment is 50~70 W, the frequency is 15~25 kHz, and the time is 8~12 min.

[0031] The implementation process of the present invention is described in detail below in conjunction with specific embodiments. However, it will be understood by those skilled in the art that the following embodiments are merely illustrative of the present invention and should not be construed as limiting the scope of the present invention. It should also be noted that, for ease of description, only the parts relevant to the invention are shown in the embodiments. It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the embodiments. It should be noted that the endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be considered to be specifically disclosed herein.

[0032] In the following examples and comparative examples, among the raw materials used, the CAS number of cellulose nanocrystals is C909405, the CAS number of N,N'-methylenebisacrylamide is 110-26-9, and the CAS number of molybdenum selenide nanosheets is 12058-18-3. The remaining raw materials are ordinary commercial products that can be directly purchased or can be prepared according to conventional techniques in the art.

[0033] 1. Example of the preparation method of the polyaniline@molybdenum selenide@cellulose nanocrystal composite material of the present invention Example 1 The preparation method of the polyaniline@molybdenum selenide@cellulose nanocrystal composite material provided in this embodiment includes the following steps: (1) 60 mg of cellulose nanocrystals were added to 50 g of deionized water and ultrasonically dispersed at an ultrasonic power of 80 W and a frequency of 25 kHz for 12 min to obtain a uniform cellulose nanocrystal dispersion. (2) Add 50 mg of acrylic acid and 0.5 mg of N,N'-methylenebisacrylamide to the cellulose nanocrystal dispersion and stir evenly to form a hydrogel precursor solution; (3) Add 120 mg of aniline monomer to the hydrogel precursor solution, stir at 300 rpm for 15 min to fully disperse, slowly add 85 mg of phytic acid, and continue stirring for 30 min to obtain a mixed solution; (4) Slowly adding 294 mg of ammonium persulfate to the mixed solution to initiate polymerization, stirring the mixture at 500 rpm in an ice-water bath for 6 h to form a preliminary composite structure, thereby obtaining a first reaction system having a polyaniline-cellulose nanocrystal composite structure; (5) 30 mg of molybdenum selenide nanosheets that had been ultrasonically treated (power 60 W, frequency 20 kHz, time 10 min) were added to the first reaction system and stirred for 4 h for deep compounding to obtain a second reaction system having a polyaniline-molybdenum selenide-cellulose nanocrystal composite structure; (6) The second reaction system was transferred to a high-pressure reactor and reacted at 120°C for 8 h. After cooling, it was washed with deionized water and anhydrous ethanol to remove unreacted products to obtain a polyaniline@molybdenum selenide@cellulose nanocrystal composite material.

[0034] Example 2 The preparation method of the polyaniline@molybdenum selenide@cellulose nanocrystal composite material provided in this embodiment includes the following steps: (1) Add 60 mg of cellulose nanocrystals to 48 g of deionized water and ultrasonically disperse them for 10 min at an ultrasonic power of 60 W and a frequency of 20 kHz to obtain a uniform cellulose nanocrystal dispersion. (2) Add 50 mg of acrylic acid and 0.25 mg of N,N'-methylenebisacrylamide to the cellulose nanocrystal dispersion and stir evenly to form a hydrogel precursor solution; (3) Add 60 mg of aniline monomer to the hydrogel precursor solution, stir at 200 rpm for 10 min to fully disperse, slowly add 48 mg of phytic acid, and continue stirring for 20 min to obtain a mixed solution; (4) Slowly adding 147 mg of ammonium persulfate to the mixed solution to initiate polymerization, stirring the mixture in an ice-water bath at 400 rpm for 5 h to form a preliminary composite structure, thereby obtaining a first reaction system having a polyaniline-cellulose nanocrystal composite structure; (5) Add 12 mg of molybdenum selenide nanosheets that have been ultrasonically treated (power 50 W, frequency 15 kHz, time 8 min) to the first reaction system and stir for 3 h for deep compounding to obtain a second reaction system having a polyaniline-molybdenum selenide-cellulose nanocrystal composite structure; (6) The second reaction system was transferred to a high-pressure reactor and reacted at 80°C for 6 h. After cooling, it was washed with deionized water and anhydrous ethanol to remove unreacted products to obtain a polyaniline@molybdenum selenide@cellulose nanocrystal composite material.

[0035] Example 3 The preparation method of the polyaniline@molybdenum selenide@cellulose nanocrystal composite material provided in this embodiment includes the following steps: (1) Add 60 mg of cellulose nanocrystals to 72 g of deionized water and ultrasonically disperse them at an ultrasonic power of 100 W and a frequency of 30 kHz for 20 min to obtain a uniform cellulose nanocrystal dispersion; (2) Add 50 mg of acrylic acid and 0.75 mg of N,N'-methylenebisacrylamide to the cellulose nanocrystal dispersion and stir evenly to form a hydrogel precursor solution; (3) Add 180 mg of aniline monomer to the hydrogel precursor solution, stir at 400 rpm for 20 min to fully disperse, slowly add 126 mg of phytic acid, and continue stirring for 40 min to obtain a mixed solution; (4) Slowly adding 441 mg of ammonium persulfate to the mixed solution to initiate polymerization, stirring the mixture in an ice-water bath at 600 rpm for 7 h to form a preliminary composite structure, thereby obtaining a first reaction system having a polyaniline-cellulose nanocrystal composite structure; (5) Add 54 mg of molybdenum selenide nanosheets that have been ultrasonically treated (power 70 W, frequency 25 kHz, time 12 min) to the first reaction system and stir for 5 h for deep compounding to obtain a second reaction system having a polyaniline-molybdenum selenide-cellulose nanocrystal composite structure; (6) The second reaction system was transferred to a high-pressure reactor and reacted at 160°C for 10 h. After cooling, it was washed with deionized water and anhydrous ethanol to remove unreacted products to obtain a polyaniline@molybdenum selenide@cellulose nanocrystal composite material.

[0036] Example 4 The preparation method of the polyaniline@molybdenum selenide@cellulose nanocrystal composite material provided in this embodiment includes the following steps: (1) Add 60 mg of cellulose nanocrystals to 48 g of deionized water and ultrasonically disperse them at an ultrasonic power of 100 W and a frequency of 20 kHz for 20 min to obtain a uniform cellulose nanocrystal dispersion; (2) Add 50 mg of acrylic acid and 0.75 mg of N,N'-methylenebisacrylamide to the cellulose nanocrystal dispersion and stir evenly to form a hydrogel precursor solution; (3) Add 180 mg of aniline monomer to the hydrogel precursor solution, stir at 200 rpm at room temperature for 20 min, slowly add 108 mg of phytic acid, and continue stirring for 40 min to obtain a mixed solution; (4) Slowly adding 441 mg of ammonium persulfate to the mixed solution to initiate polymerization, stirring the mixture in an ice-water bath at 400 rpm for 7 h to form a preliminary composite structure, thereby obtaining a first reaction system having a polyaniline-cellulose nanocrystal composite structure; (5) Add 54 mg of molybdenum selenide nanosheets that have been ultrasonically treated (power 50 W, frequency 25 kHz, time 12 min) to the first reaction system and stir for 3 h for deep compounding to obtain a second reaction system having a polyaniline-molybdenum selenide-cellulose nanocrystal composite structure; (6) The second reaction system was transferred to a high-pressure reactor and reacted at 80°C for 10 h. After cooling, it was washed with deionized water and anhydrous ethanol to remove unreacted products to obtain a polyaniline@molybdenum selenide@cellulose nanocrystal composite material.

[0037] Example 5 The preparation method of the polyaniline@molybdenum selenide@cellulose nanocrystal composite material provided in this embodiment includes the following steps: (1) Add 60 mg of cellulose nanocrystals to 72 g of deionized water and ultrasonically disperse them at an ultrasonic power of 60 W and a frequency of 30 kHz for 10 min to obtain a uniform cellulose nanocrystal dispersion. (2) Add 50 mg of acrylic acid and 0.25 mg of N,N'-methylenebisacrylamide to the cellulose nanocrystal dispersion and stir evenly to form a hydrogel precursor solution; (3) Add 60 mg of aniline monomer to the hydrogel precursor solution, stir at 400 rpm for 10 min at room temperature, slowly add 42 mg of phytic acid, and continue stirring for 20 min to obtain a mixed solution; (4) Slowly adding 147 mg of ammonium persulfate to the mixed solution to initiate polymerization, stirring the mixture in an ice-water bath at 600 rpm for 5 h to form a preliminary composite structure, thereby obtaining a first reaction system having a polyaniline-cellulose nanocrystal composite structure; (5) Add 12 mg of molybdenum selenide nanosheets that have been ultrasonically treated (power 70 W, frequency 15 kHz, time 8 min) to the first reaction system and stir for 5 h for deep compounding to obtain a second reaction system having a polyaniline-molybdenum selenide-cellulose nanocrystal composite structure; (6) The second reaction system was transferred to a high-pressure reactor and reacted at 160°C for 6 h. After cooling, it was washed with deionized water and anhydrous ethanol to remove unreacted products to obtain a polyaniline@molybdenum selenide@cellulose nanocrystal composite material.

[0038] 2. Experimental Examples Experimental Example 1 The polyaniline@molybdenum selenide@cellulose nanocrystal composite material prepared in Example 3 was characterized by using a Zeiss Sigma300 SEM. The test results are as follows: Figure 1 As shown, it can be seen that the polyaniline@molybdenum selenide@cellulose nanocrystal composite material prepared in Example 3 presents a uniform three-dimensional interconnected network structure and has a large electrochemically active specific surface area, which is conducive to promoting the occurrence of electrochemical reactions.

[0039] Experimental Example 2 The electrochemical performance of the polyaniline@molybdenum selenide@cellulose nanocrystal composite materials prepared in Examples 1-5 above was tested.

[0040] Specifically, the composite materials prepared in Examples 1-5 were mixed with acetylene black and polytetrafluoroethylene (PTFE) in a mass ratio of 8:1:1 and coated onto carbon cloth to form a working electrode. A three-electrode system was assembled using a platinum sheet as the counter electrode, a saturated calomel electrode as the reference electrode, and 1 M H₂SO₄ as the electrolyte. Galvanostatic charge-discharge (GCD) tests were conducted to verify the performance of the composite materials as supercapacitor electrode materials. The results of the GCD tests at various current densities are shown in Table 1.

[0041] Table 1 Discharge specific capacity of Examples 1-5 at different current densities

[0042] As shown in Table 1, the polyaniline@molybdenum selenide@cellulose nanocrystal composite materials prepared in Examples 1-5 exhibited high specific discharge capacities at various current densities. At a current density of 0.5 A / g, the polyaniline@molybdenum selenide@cellulose nanocrystal composite material prepared in Example 3 exhibited the highest specific discharge capacity, reaching a maximum of 801.7 F / g. This also demonstrates that the polyaniline@molybdenum selenide@cellulose nanocrystal composite materials prepared in Examples 1-5 possessed excellent electrochemical performance.

[0043] At the same time, the polyaniline@molybdenum selenide@cellulose nanocrystal composite material prepared in Example 3 was subjected to charge and discharge tests at a current density of 0.5-10 A / g. The results are as follows: Figure 2 As shown in Figure 2, it can be seen that the charge and discharge curves of the polyaniline@molybdenum selenide@cellulose nanocrystal composite material prepared by the present invention at different current densities are basically consistent, indicating that the material has good rate performance. Figure 3 As shown in Figure 2, it can be seen that the CV curve of the polyaniline@MoSe@cellulose nanocrystal composite material has obvious electrochemical bulging, indicating that the electrochemical response of the material is relatively sensitive. The AC impedance test in the frequency range of 0.01 Hz~100 KHz is shown in Figure 2. Figure 4 As shown, it can be seen that the material has small internal resistance and interface resistance.

[0044] This shows that the polyaniline@molybdenum selenide@cellulose nanocrystal composite material prepared by the preparation method of the polyaniline@molybdenum selenide@cellulose nanocrystal composite material of the present invention has high specific capacitance, good rate performance and structural cycle stability, is suitable for the electrode material of supercapacitor, and improves the energy density and cycle life of the supercapacitor.

[0045] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A method for preparing a polyaniline@molybdenum selenide@cellulose nanocrystal composite material, characterized in that: The following steps are involved: Step 1: adding acrylic acid and a cross-linking agent to a cellulose nanocrystal dispersion to obtain a hydrogel precursor solution; Step 2: sequentially adding aniline monomer, dopant and initiator to the hydrogel precursor solution to carry out polymerization reaction and first compounding to obtain a first reaction system having a polyaniline-cellulose nanocrystal composite structure; Step 3, adding molybdenum selenide nanosheets to the first reaction system for a second composite, thereby obtaining a second reaction system having a polyaniline-molybdenum selenide-cellulose nanocrystal composite structure; Step 4: placing the second reaction system in a high-pressure reactor to carry out liquid-phase reaction, followed by cooling and washing to obtain a polyaniline@molybdenum selenide@cellulose nanocrystal composite material.

2. The method for preparing the polyaniline@molybdenum selenide@cellulose nanocrystal composite material according to claim 1, characterized in that: The mass ratio of the acrylic acid to the cellulose nanocrystals in the cellulose nanocrystal dispersion is 1:(1-1.2); the mass ratio of the aniline monomer to the cellulose nanocrystals in the cellulose nanocrystal dispersion is (1-3):

1.

3. The method for preparing the polyaniline@molybdenum selenide@cellulose nanocrystal composite material according to claim 2, characterized in that: The cross-linking agent is N,N'-methylenebisacrylamide, and the mass of the N,N'-methylenebisacrylamide is 0.5-1.5% of the mass of acrylic acid.

4. The method for preparing the polyaniline@molybdenum selenide@cellulose nanocrystal composite material according to claim 2, characterized in that: The dopant is phytic acid, and the mass ratio of the phytic acid to the aniline monomer is (0.6-0.8):

1.

5. The method for preparing the polyaniline@molybdenum selenide@cellulose nanocrystal composite material according to claim 2, characterized in that: The initiator is ammonium persulfate, and the mass ratio of the ammonium persulfate to the aniline monomer is 2.45:

1.

6. The method for preparing the polyaniline@molybdenum selenide@cellulose nanocrystal composite material according to claim 2, characterized in that: The added amount of the molybdenum selenide nanosheets is 20-30% of the mass of the aniline monomer.

7. The method for preparing the polyaniline@molybdenum selenide@cellulose nanocrystal composite material according to claim 1, characterized in that: The temperature of the liquid phase reaction is 80-160° C., and the time is 6-10 hours.

8. The method for preparing the polyaniline@molybdenum selenide@cellulose nanocrystal composite material according to claim 1, characterized in that: The preparation method of the cellulose nanocrystal dispersion comprises: The cellulose nanocrystals are added into deionized water and dispersed by ultrasonication to obtain a uniform cellulose nanocrystal dispersion; The mass ratio of the cellulose nanocrystals to deionized water is 1:(800-1200), the ultrasonic dispersion has a power of 60-100 W, a frequency of 20-30 kHz, and a time of 10-20 min.

9. A polyaniline@molybdenum selenide@cellulose nanocrystal composite material, characterized in that: The composite material is prepared by the method for preparing the polyaniline@molybdenum selenide@cellulose nanocrystal composite material according to any one of claims 1 to 8.

10. A method for preparing the polyaniline@molybdenum selenide@cellulose nanocrystal composite material according to any one of claims 1 to 8, wherein the polyaniline@molybdenum selenide@cellulose nanocrystal composite material is prepared, or the polyaniline@molybdenum selenide@cellulose nanocrystal composite material according to claim 9 is used in supercapacitor electrodes.

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