Polypyrrole conductive material with hollow nanocage structure as well as preparation method and application of polypyrrole conductive material

Abstract

The invention relates to a polypyrrole conductive material with a hollow nanocage structure and a preparation method and application thereof, and belongs to the technical field of preparation of nano conductive materials, the method comprises the steps that pyrrole is polymerized on the surface of nano zinc oxide in situ, the mass ratio of pyrrole to nano zinc oxide is (0.5-1.5): 1, and a PPy / ZnO composite material with a core-shell structure is obtained; and dispersing the PPy / ZnO composite material with the core-shell structure in an acid solution, and etching the nano zinc oxide through double decomposition reaction to obtain the polypyrrole conductive material with the hollow nano-cage structure. The process controllability is high, the prepared polypyrrole nanocage has an ultrathin shell layer and a clear hollow cavity, a large specific surface area and rich internal and external reaction interfaces are provided, rapid diffusion of electrolyte ions and charge storage are facilitated, and excellent electrochemical performance is shown when the polypyrrole nanocage serves as an electrode material.

Description

Technical Field

[0001] This invention belongs to the field of nano-conductive material preparation technology, specifically a hollow nanocage structure polypyrrole conductive material, its preparation method, and its application. Background Technology

[0002] Conductive polymers are a class of high-molecular materials with a conjugated backbone structure. This structure allows electrons to be delocalized on the molecular chains, thus endowing the material with conductivity. However, the strength of conductivity depends on a variety of factors, including the polymer's molecular structure, degree of doping, chain arrangement, and orientation.

[0003] Polypyrrole (PPy) possesses excellent electrical conductivity and exhibits good pseudocapacitive properties due to its good redox reversibility and surface activity, making it promising for applications in energy storage and sensing. However, PPy prepared by traditional methods is mostly in the form of dense particles or thin films, which suffers from limited specific surface area, long ion diffusion paths, and low utilization of internal active sites. Especially when used as an electrode material, increasing the thickness to improve loading leads to severe ion transport obstruction and capacity decay.

[0004] Hollow nanostructures can effectively increase the specific surface area of ​​polypyrrole and shorten the ion diffusion distance, which is an effective way to improve its performance. Currently, template methods are commonly used to prepare hollow materials, but these methods suffer from difficulties in template removal, complex processes, and the inability to precisely control shell thickness and structural uniformity. For example, the invention patent CN115432744A, entitled "A Preparation Method and Application of Hollow Nanocage Structured Bimetallic Hydroxide Material," uses a metal-organic framework (ZIF-67) as a template to prepare bimetallic hydroxide nanocages. This process involves multiple steps and precise control of different metal salts, and the final product is an inorganic hydroxide, making it impossible to directly obtain highly conductive hollow polypyrrole nanocages. Therefore, developing a simple, structurally controllable method for preparing hollow nanocages suitable for conductive polymers like polypyrrole is of great significance for promoting the development of high-performance polymer functional materials. Summary of the Invention

[0005] To address the problems existing in the prior art, this invention provides a hollow nanocage structured polypyrrole conductive material, its preparation method, and its application. The process is simple and the structural parameters are controllable. By using the sacrificial template method, hollow polypyrrole nanocages with ultra-thin shells and complete structures can be efficiently prepared, which is of great significance for promoting the development of high-performance polymer functional materials.

[0006] This invention is achieved through the following technical solution: A method for preparing a hollow nanocage-structured polypyrrole conductive material specifically includes the following steps: Step 1: Pyrrole is polymerized in situ onto the surface of nano-zinc oxide, with a mass ratio of pyrrole to nano-zinc oxide of (0.5-1.5):1, to obtain a core-shell structured PPy / ZnO composite material; Step 2: The core-shell structured PPy / ZnO composite material is dispersed in an acidic solution, and nano-zinc oxide is etched through a metathesis reaction to obtain a hollow nanocage structured polypyrrole conductive material.

[0007] Preferably, the nano zinc oxide described in step 1 is in the shape of short rods with an average length of 50-60 nm.

[0008] Preferably, in step 1, 0.5-1 g of nano zinc oxide is uniformly dispersed in 100 mL of deionized water, pyrrole and p-toluenesulfonic acid are added and ultrasonically dispersed, with a mass ratio of nano zinc oxide to p-toluenesulfonic acid of 1:1. Then, ferric chloride aqueous solution is added, and the mixture is reacted at 0-3°C for 5-7 h. After centrifugation, washing, and vacuum filtration, a core-shell structured PPy / ZnO composite material is obtained.

[0009] Furthermore, the concentration of the ferric chloride aqueous solution is 1.5~2.0 g / mL, and the volume ratio of the ferric chloride aqueous solution to deionized water is (30-50):100. The solution is added dropwise in several portions at 0-3°C while stirring, and then the reaction is carried out to obtain the core-shell structured PPy / ZnO composite material.

[0010] Preferably, the acidic solution in step 2 is hydrochloric acid.

[0011] Furthermore, the H in the hydrochloric acid + The concentration is 0.5-2 M.

[0012] Preferably, after etching away the nano-zinc oxide in step 3, the product is centrifuged, washed, and allowed to stand before being collected to obtain a hollow nanocage structured polypyrrole conductive material.

[0013] A hollow nanocage structured polypyrrole conductive material obtained by the preparation method of the hollow nanocage structured polypyrrole conductive material described in any one of the above methods.

[0014] Preferably, the polypyrrole conductive material has an average outer diameter of 40-70 nm and a shell thickness of 2-4 nm.

[0015] A bacterial cellulose / polypyrrole composite electrode film, wherein the substrate of the composite electrode film is bacterial cellulose, and a hollow nanocage structured polypyrrole conductive material is grafted in situ onto the surface of the bacterial cellulose.

[0016] Compared with the prior art, the present invention has the following beneficial technical effects: This invention discloses a method for preparing a hollow nanocage-structured polypyrrole conductive material. Nano-zinc oxide is used as a nanoscale sacrificial template. The process is simple, requiring only two key reactions, and the template is completely etched, resulting in a pure product. By selecting nano-zinc oxide as the sacrificial template, its excellent acid solubility allows for complete removal under mild conditions, avoiding structural damage that may occur with physical removal methods and ensuring the integrity of the hollow structure. This invention offers strong process controllability, and the resulting polypyrrole nanocages possess ultrathin shells and well-defined hollow cavities, providing a large specific surface area and abundant internal and external reaction interfaces. This facilitates rapid diffusion of electrolyte ions and charge storage, resulting in excellent electrochemical performance when used as an electrode material. Attached Figure Description

[0017] Figure 1 This is a transmission electron microscope (TEM) image of the hollow polypyrrole nanocage prepared in Example 1 of the present invention.

[0018] Figure 2 This is a scanning electron microscope (SEM) image of the hollow polypyrrole nanocages prepared in Example 1 of the present invention.

[0019] Figure 3 The nitrogen adsorption-desorption isotherms and pore size distribution diagrams are shown for the hollow polypyrrole nanocages prepared in Example 1 of this invention and the conventional in-situ polymerized BC / PPy membrane.

[0020] Figure 4 The electrodes prepared using the materials of Example 1 and the in-situ polymerized BC / PPy electrode of Comparative Example 1 were tested at 5 mV / s. -1 Cyclic voltammetry (CV) curves at scan rate.

[0021] Figure 5 The images show the constant current charge-discharge (GCD) curves of the electrode prepared using the material of Example 1 under different current densities. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0023] This invention discloses a method for preparing a hollow nanocage-structured polypyrrole conductive material, comprising the following steps: Step 1, Preparation of core-shell structured PPy / ZnO composite material: 0.5-1 g of nanoscale sacrificial template short rod-shaped zinc oxide nanoparticles (average length 50-60 nm) were uniformly dispersed in 100 mL of deionized water as a dispersant. Pyrrole monomer and dopant p-toluenesulfonic acid were added and ultrasonically dispersed. The mass ratio of pyrrole monomer to sacrificial template and p-toluenesulfonic acid was (0.5-1.5):1:1. Under stirring and low temperature conditions of 0-3°C, ferric chloride aqueous solution with a concentration of 1.5-2.0 g / mL was slowly added dropwise in several portions. The volume ratio of ferric chloride aqueous solution to deionized water was (30-50):100. After the addition was completed, the reaction was carried out for 5-7 hours, which initiated the in-situ polymerization of pyrrole on the template surface to form a core-shell structure of polypyrrole-coated template. After centrifugation, washing and vacuum filtration, the core-shell structured PPy / ZnO composite material was obtained.

[0024] Step 2, Preparation of hollow PPy nanocages: The PPy / ZnO composite material obtained in step 1 is dispersed in H + In an acid solution (hydrochloric acid) with a concentration of 0.5-2 M, the internal sacrificial template is completely etched through a metathesis reaction. After centrifugation, washing, and settling, a hollow nanocage structure of polypyrrole conductive material is obtained.

[0025] This invention discloses a hollow nanocage structure of polypyrrole conductive material, which is a spherical hollow structure with an average outer diameter of 40-70 nm and a shell thickness of 2-4 nm.

[0026] The present invention discloses an electrode film obtained by in-situ grafting of the above-mentioned hollow nanocage structured polypyrrole conductive material as an active substance onto the surface of bacterial cellulose (as a substrate).

[0027] Example 1 This embodiment provides a method for preparing a hollow nanocage-structured polypyrrole conductive material, the specific steps of which are as follows: Step 1. Preparation of core-shell structured PPy / ZnO composite material: Weigh 0.8 g of short rod-shaped nano zinc oxide (average length 55 nm) and disperse it in 100 mL of deionized water. Stir for 12 hours to obtain a suspension.

[0028] Subsequently, 0.6 mL of pyrrole monomer and 0.8 g of p-toluenesulfonic acid were added to the suspension, and the mixture was ultrasonically dispersed for 2 hours to obtain a mixed system.

[0029] The mixture was placed in an ice bath at 1°C, and 35 mL of ferric chloride hexahydrate aqueous solution with a concentration of 1.94 g / mL was slowly added dropwise in three portions with stirring. After the addition was completed, the reaction was continued at a low temperature of 1°C for 6 hours.

[0030] After the reaction was completed, the product in the reaction system was washed by centrifugation with deionized water and then vacuum filtered to obtain the core-shell structured PPy / ZnO composite material.

[0031] Step 2. Preparation of hollow PPy nanocages: The obtained PPy / ZnO composite material was redispersed in a 1 M HCl solution prepared with 2.3 g of concentrated hydrochloric acid, and stirred under ultrasonic assistance for 3 hours to completely etch the ZnO template. After the reaction was completed, the product was washed with a large amount of deionized water by centrifugation until the supernatant was neutral. After standing for 6 hours, the product was collected to obtain the hollow nanocage structured polypyrrole conductive material.

[0032] In this embodiment, the polypyrrole conductive material is grafted in situ onto the surface of bacterial cellulose (BC) to form an electrode film.

[0033] Comparative Example 1 A BC (bacterial cellulose) / PPy electrode film was prepared using a traditional in-situ polymerization method as a comparison. The specific process is as follows: Large pieces of BC were rinsed repeatedly with deionized water several times to remove acetic acid. They were then cut into small pieces, dispersed and broken down using a commercial fiber disperser (7500 rpm), and prepared to a concentration of 3.2 mg / mL. -1 The BC suspension is ready for use.

[0034] 0.5 mL of Py(pyrrole) monomer and 1.33 g of p-toluenesulfonic acid were slowly added to 100 mL of BC suspension, and the mixture was sonicated for 30 min. After 30 min, 50 mL of a 1.94 g / mL solution was slowly added in three portions at 1 °C. -1 Add an aqueous solution of FeCl3 to the above mixture and continue stirring at 1 °C for 6 h to prepare a BC / PPy suspension.

[0035] Subsequently, the suspension was vacuum filtered through a 0.22 μm porous nitrocellulose membrane and then vacuum dried at 60 °C for 12 h. The resulting film sample was then peeled off the nitrocellulose membrane to obtain the electrode film.

[0036] The product obtained in this embodiment was characterized as follows: Morphological analysis: like Figure 1 As shown in the TEM image, the product exhibits a clear spherical hollow structure with an average diameter of approximately 55 nm and a uniform shell thickness of approximately 3 nm.

[0037] Figure 2 (SEM image) further reveals the spherical morphology of the nanocage.

[0038] Structural analysis: Figure 3 Figure B shows that the nitrogen adsorption-desorption isotherm of the material in Example 1 is type IV, exhibiting obvious mesoporous characteristics. Its specific surface area, obtained by the BET test method, is 32.81 m². 2 The surface area was 20.45 m² / g, with an average pore size of 13.28 nm. Figure A shows that the specific surface area obtained by the BET test method in Comparative Example 1 was only 20.45 m² / g, with an average pore size of 7.34 nm. Figure C shows that the pore volume of the material in Example 1 was 0.109 cm³ / g. 3 / g, the pore volume of the material in Comparative Example 1 is 0.077 cm³. 3 / g, therefore, the specific surface area, average pore size and pore volume of Example 1 are significantly higher than those of the PPy material in Comparative Example 1, confirming that the successful construction of the hollow structure brings about the characteristic of high specific surface area.

[0039] Electrochemical performance testing: The materials of Example 1 and Comparative Example 1 were tested in a three-electrode system (1 M H2SO4 electrolyte) under the same conditions and parameters.

[0040] Figure 4 The CV curves show that at 5 mV s -1 At the scanning rate, the CV curve of the electrode of Example 1 exhibits a near-rectangular shape, while the CV curve of the electrode of Comparative Example 1 has poor rectangularity. This indicates that when the material of Example 1 is used as an electrode, it has superior charge storage and release capabilities, as well as faster charge and discharge response speed.

[0041] Figure 5 The GCD curves show that, under various current densities, the charge-discharge curves approximate symmetrical triangles with small voltage drops, and the maximum areal capacitance can be calculated to be 2146 mF / cm². -2 It exhibits excellent charge storage capability.

[0042] Example 2 This embodiment provides a method for preparing a hollow nanocage structured polypyrrole conductive material. The specific steps differ from those in Example 1 in that the amount of pyrrole monomer added in step 1 is adjusted to 0.4 mL, while the other steps and parameters are exactly the same as in Example 1.

[0043] By adjusting the monomer dosage and reducing the amount of pyrrole monomer, the total amount of polypyrrole polymerized and deposited on the template surface is correspondingly reduced. This results in a decrease in the thickness and overall outer diameter of the final nanocage shell. This thinner shell structure further shortens the path for ions to diffuse from the electrolyte into the material's interior, increasing the effective electrochemical active area, thereby helping to improve the material's ion transport efficiency and charge storage capacity.

[0044] Example 3 This embodiment provides a method for preparing a hollow nanocage structured polypyrrole conductive material. The specific steps differ from those in Example 1 in that the concentration of hydrochloric acid in step 2 is adjusted to 0.5 M, and the etching reaction time is extended to 6 hours. Other steps and parameters are exactly the same as in Example 1.

[0045] This embodiment achieves a gentler and more controllable chemical etching of the ZnO template by reducing the hydrochloric acid concentration and correspondingly extending the reaction time. The lower acid concentration slows down the etching reaction rate, allowing for a uniform and stable construction of the reaction interface; while the sufficient reaction time ensures that the template can be completely removed. This avoids mechanical stress caused by excessively rapid or locally intense reactions, thereby maximizing the integrity of the polypyrrole shell structure and yielding hollow nanocage products with fewer surface defects.

[0046] The above embodiments demonstrate that the method provided by this invention can successfully prepare structurally regular hollow polypyrrole nanocages. This material possesses a high specific surface area and a cavity structure, exhibiting excellent capacitance performance in electrochemical testing, and has broad application prospects in supercapacitor electrodes, sensors, catalyst supports, and other fields.

[0047] Example 4 This embodiment provides a method for preparing a hollow nanocage-structured polypyrrole conductive material, the specific steps of which are as follows: Step 1. Preparation of core-shell structured PPy / ZnO composite material: Weigh 0.8 g of short rod-shaped nano zinc oxide (average length 50 nm) and disperse it in 100 mL of deionized water. Stir for 10 hours to obtain a suspension.

[0048] Subsequently, 0.6 mL of pyrrole monomer and 0.8 g of p-toluenesulfonic acid were added to the suspension, and the mixture was ultrasonically dispersed for 2 hours to obtain a mixed system.

[0049] The mixture was placed in an ice bath at 0°C, and 30 mL of ferric chloride hexahydrate aqueous solution with a concentration of 2 g / mL was slowly added dropwise in 4 portions with stirring. After the addition was completed, the reaction was continued at 0°C for 7 hours.

[0050] After the reaction was completed, the product in the reaction system was washed by centrifugation with deionized water and then vacuum filtered to obtain the core-shell structured PPy / ZnO composite material.

[0051] Step 2. Preparation of hollow PPy nanocages: The obtained PPy / ZnO composite material was redispersed in a 0.5 M HCl solution prepared with 2.3 g of concentrated hydrochloric acid, and stirred under ultrasonic assistance for 2.5 hours to completely etch the ZnO template. After the reaction was complete, the product was washed with a large amount of deionized water by centrifugation until the supernatant was neutral. After standing for 5 hours, the product was collected to obtain the hollow nanocage structured polypyrrole conductive material.

[0052] Example 5 This embodiment provides a method for preparing a hollow nanocage-structured polypyrrole conductive material, the specific steps of which are as follows: Step 1. Preparation of core-shell structured PPy / ZnO composite material: Weigh 0.8 g of short rod-shaped nano zinc oxide (average length 60 nm) and disperse it in 100 mL of deionized water. Stir for 13 hours to obtain a suspension.

[0053] Subsequently, 0.6 mL of pyrrole monomer and 0.8 g of p-toluenesulfonic acid were added to the suspension, and the mixture was ultrasonically dispersed for 2 hours to obtain a mixed system.

[0054] The mixture was placed in an ice bath at 3°C, and 50 mL of ferric chloride hexahydrate aqueous solution with a concentration of 1.5 g / mL was slowly added dropwise in 5 portions with stirring. After the addition was completed, the reaction was continued at a low temperature of 3°C for 5 hours.

[0055] After the reaction was completed, the product in the reaction system was washed by centrifugation with deionized water and then vacuum filtered to obtain the core-shell structured PPy / ZnO composite material.

[0056] Step 2. Preparation of hollow PPy nanocages: The obtained PPy / ZnO composite material was redispersed in a 2 M HCl solution prepared with 2.3 g of concentrated hydrochloric acid, and stirred under ultrasonic assistance for 8 hours to completely etch the ZnO template. After the reaction was completed, the product was washed with a large amount of deionized water by centrifugation until the supernatant was neutral. After standing for 7 hours, the product was collected to obtain the hollow nanocage structured polypyrrole conductive material.

[0057] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a hollow nanocage-structured polypyrrole conductive material, characterized in that, Includes the following steps: S1, pyrrole is polymerized in situ onto the surface of nano-zinc oxide, with a mass ratio of pyrrole to nano-zinc oxide of (0.5-1.5):1, to obtain a core-shell structured PPy / ZnO composite material; S2, core-shell structured PPy / ZnO composite material is dispersed in an acidic solution, and nano-zinc oxide is etched through metathesis reaction to obtain hollow nanocage structured polypyrrole conductive material.

2. The method for preparing the hollow nanocage structured polypyrrole conductive material according to claim 1, characterized in that, The zinc oxide nanoparticles described in S1 are short rods with an average length of 50-60 nm.

3. The method for preparing the hollow nanocage structured polypyrrole conductive material according to claim 1, characterized in that, S1. 0.5-1 g of nano zinc oxide was uniformly dispersed in 100 mL of deionized water. Pyrrole and p-toluenesulfonic acid were added and ultrasonically dispersed. The mass ratio of nano zinc oxide to p-toluenesulfonic acid was 1:

1. Then, ferric chloride aqueous solution was added and reacted at 0-3°C for 5-7 h. After centrifugation, washing and vacuum filtration were performed to obtain the core-shell structured PPy / ZnO composite material.

4. The method for preparing the hollow nanocage structured polypyrrole conductive material according to claim 3, characterized in that, The concentration of the ferric chloride aqueous solution is 1.5~2.0 g / mL, and the volume ratio of the ferric chloride aqueous solution to deionized water is (30-50):

100. The solution is added dropwise in several portions at 0-3°C while stirring, and then the reaction is carried out to obtain the core-shell structured PPy / ZnO composite material.

5. The method for preparing the hollow nanocage structured polypyrrole conductive material according to claim 1, characterized in that, The acidic solution mentioned in S2 is hydrochloric acid.

6. The method for preparing the hollow nanocage structured polypyrrole conductive material according to claim 5, characterized in that, H in hydrochloric acid + The concentration is 0.5-2 M.

7. The method for preparing the hollow nanocage structured polypyrrole conductive material according to claim 1, characterized in that, After etching away the nano-zinc oxide using S3, the product was centrifuged, washed, and allowed to stand before being collected to obtain a hollow nanocage structured polypyrrole conductive material.

8. A hollow nanocage structured polypyrrole conductive material obtained by the preparation method of the hollow nanocage structured polypyrrole conductive material according to any one of claims 1 to 7.

9. The hollow nanocage structured polypyrrole conductive material according to claim 8, characterized in that, The polypyrrole conductive material has an average outer diameter of 40-70 nm and a shell thickness of 2-4 nm.

10. A bacterial cellulose / polypyrrole composite electrode film, characterized in that, The substrate of the composite electrode film is bacterial cellulose, and the surface of the bacterial cellulose is grafted in situ with polypyrrole conductive material with a hollow nanocage structure as described in claim 8 or 9.

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