Polypyrrole-modified nylon-based carbon electrode material for fuel cells and preparation method thereof

Abstract

The present invention belongs to the technical field of preparation of fuel cell electrode materials, and specifically relates to a polypyrrole-modified nylon-based fuel cell carbon electrode material and a preparation method thereof. The preparation method first performs low-temperature carbonization on nylon aerogel, then uniformly disperses the low-temperature carbonized nylon aerogel powder and polyvinyl pyrrolidone, then drips pyrrole monomer, and in-situ polymerizes to obtain polypyrrole-modified low-temperature carbonized powder; finally, high-temperature carbonization is performed to obtain a polypyrrole-modified nylon-based fuel cell carbon electrode material. The present invention prepares carbon aerogel by a sol-gel method. The carbon aerogel has a high specific surface area, excellent pore size distribution and lightweight properties, which provide great advantages for its application in electrode materials. The nitrogen element in the five-membered ring of polypyrrole is an ideal element for doping nylon-based carbon aerogel, which can increase the conductivity of nylon-based carbon aerogel and has broad application prospects in the field of fuel cells.

Description

Technical Field

[0001] The present invention belongs to the technical field of fuel cell electrode material preparation, and in particular relates to a carbon electrode material for a polypyrrole-modified nylon-based fuel cell and a preparation method thereof. Background Art

[0002] A fuel cell is an electrochemical device that directly converts the chemical energy of a fuel and an oxidant into electrical energy. The operating principle of a fuel cell is as follows: After the fuel (a compound containing C-H bonds or hydrogen) is introduced into the anode in the form of gaseous molecules, an oxidation reaction occurs, releasing electrons. These electrons travel through an external circuit, through a load, and reach the cathode, simultaneously providing electrical energy for the external circuit. At the cathode, the oxidant receives electrons, reducing oxygen atoms to oxygen ions, which then reach oxygen vacancies in the electrolyte. Driven by an oxygen concentration gradient, these oxygen vacancies diffuse from the anode to the cathode, ultimately reaching the electrolyte-cathode interface and participating in the reaction. This process involves no combustion; instead, the electrochemical reaction combines oxygen and hydrogen into water, converting chemical energy into electrical energy. Therefore, the energy conversion efficiency of fuel cells is not limited by the Carnot cycle and can reach 60% to 80%. Furthermore, the reaction produces virtually no nitrogen or sulfide products, making it very environmentally friendly. Because fuel cells lack the mechanical components of heat engines, they produce virtually no noise pollution during operation. Furthermore, their wide range of fuel sources makes fuel cells promising for future development.

[0003] Fuel cells have numerous advantages, making them widely used in transportation, military, and mobile devices such as cell phones. They hold broad prospects and enormous development potential. However, fuel cells still face numerous challenges, such as relatively high electrode costs, short electrode lifespans, and fuel constraints, all of which limit their commercialization. To date, although fuel cells still rely heavily on Pt-based electrode materials for both electrodes, platinum is an expensive precious metal that is both very expensive and has very limited reserves, making fuel cell manufacturing costs very high and a major factor hindering fuel cell development. Furthermore, Pt-based electrode materials have very poor methanol toxicity resistance, resulting in Pt waste and unmanageable fuel cell costs. Therefore, for electrode materials, it is necessary not only to improve the precious metal catalytic structure but also to increase its efficiency, while also seeking inexpensive and efficient alternative electrode materials. Summary of the Invention

[0004] The present invention aims to provide a polypyrrole-modified nylon-based carbon electrode material for fuel cells and a method for preparing the same. The polypyrrole-modified nylon-based carbon electrode material for fuel cells not only has a high specific surface area but also high electrical conductivity, thus resolving the problems of existing carbon electrode materials.

[0005] In order to solve the above technical problems, the present invention adopts the following technical solutions:

[0006] A method for preparing a carbon electrode material for a polypyrrole-modified nylon-based fuel cell comprises the following steps:

[0007] (1) Nylon particles were added to a formic acid solution, dispersed evenly by ultrasonication, and then freeze-dried to prepare nylon aerogel;

[0008] (2) Under inert gas conditions, the nylon aerogel is carbonized at a low temperature of 500-600°C;

[0009] The surface of nylon aerogels pyrolyzed at low temperatures has more defects, which allow for better adhesion of polyvinyl pyrrole and pyrrole monomers, facilitating in-situ polymerization of the pyrrole monomers. Excessively high temperatures can prematurely carbonize the nylon aerogel, rendering its surface inert and making it difficult for the pyrrole monomers to polymerize in-situ on its surface and within its pores, hindering the nitrogen doping process.

[0010] (3) The low-temperature carbonized nylon aerogel is ground and pulverized to obtain a low-temperature carbonized powder. The low-temperature carbonized powder and polyvinyl pyrrolidone are first uniformly dispersed in deionized water, allowed to stand for a period of time, and then pyrrole monomer is added dropwise to obtain a mixed solution; an aqueous solution containing an oxidant is added dropwise to the mixed solution under stirring, and the mixture is reacted for a period of time to obtain a polypyrrole-modified low-temperature carbonized powder; the mass ratio of the low-temperature carbonized powder to polyvinyl pyrrolidone and pyrrole monomer is 1: (0.05-0.35): (0.01-0.3);

[0011] Commonly used polyvinylpyrrolidone (PVP) has a number-average molecular weight of 5,000-250,000. Its molecular structure contains hydrophilic pyrrolidone groups and a hydrophobic C−C backbone. This amphiphilic nature enables it to bind to the surface of the low-temperature carbonized powder, forming an adsorption film that modifies the surface properties and generates repulsive forces, preventing aggregation and thus maintaining the stability of the dispersion. Furthermore, the pyrrole rings on the side chains of PVP can form hydrogen bonds with pyrrole monomers, acting as a template to some extent, promoting uniform dispersion of the pyrrole monomer on the surface of the low-temperature carbonized powder and improving the uniformity of the polypyrrole. Furthermore, the uniformly polymerized polypyrrole improves the mechanical properties of the low-temperature carbonized powder and prevents structural collapse during the subsequent high-temperature carbonization process. Furthermore, the mass ratio of low-temperature carbonized powder to PVP to pyrrole monomer is 1:(0.1-0.3):(0.01-0.3). Since polyvinyl pyrrolidone plays the dual role of dispersant and template, it needs to be mixed with the low-temperature carbonized powder in advance to promote the uniform dispersion of polypyrrole on the surface and in the pores of the low-temperature carbonized powder.

[0012] (4) The polypyrrole-modified low-temperature carbonized powder is subjected to high-temperature carbonization under the protection of an inert gas, and the high-temperature carbonization temperature is 950-1150°C, thereby obtaining a polypyrrole-modified nylon-based carbon electrode material for a fuel cell.

[0013] At an appropriate carbonization temperature, the carbon elements in the polymer molecular chain will rearrange to form an ordered carbon structure, thereby improving the conductivity of the material. Furthermore, the high temperature carbonization temperature is 1000-1100. Generally speaking, as the carbonization temperature increases, the degree of graphitization of the polymer microcrystalline structure increases, which directly leads to an improvement in conductivity. However, too high a temperature will lead to the destruction of the network structure, affecting the formation of the conductive path, and will instead cause a decrease in conductivity.

[0014] The preparation technology of carbon materials is mature and is gradually being commercialized. Carbon materials are widely available, low-cost, high specific surface area, and simple to process. At present, the carbon materials used to prepare electrode materials include activated carbon, carbon nanotubes, graphene, carbon fiber, and carbon aerogel. Among them, carbon aerogel has received more and more attention due to its high specific surface area performance. Nylon itself is a nitrogen-containing polymer material, and the carbon aerogel prepared using nylon has good performance. The present invention prepares carbon aerogel by a sol-gel method. The carbon aerogel has high specific surface area, excellent pore size distribution and lightweight properties, which provide great advantages for its application in electrode materials. However, the conductivity of pure carbon aerogel is still insufficient. To this end, the present invention uses conductive polypyrrole to perform nitrogen doping modification.

[0015] Among many conductive polymers, polypyrrole (PP) boasts a relatively low cost and simple preparation process. More importantly, the pyrrole ring in its structure acts as structural nitrogen, which can significantly enhance the performance of linear nylon-based carbon aerogels. The nitrogen in the five-membered ring of PP is the ideal element for doping nylon-based carbon aerogels. The two elements have similar atomic radii, so the nitrogen doping process minimizes disruption to the nylon-based carbon aerogel's crystal lattice. Furthermore, because nitrogen atoms carry lone pairs of electrons, doping them into nylon-based carbon aerogels can increase the charge density of the carbon material, forming an n-type semiconductor and thus enhancing its conductivity. Nitrogen doping can also create defects in the nylon-based carbon aerogel structure, increasing its activity during electrochemical reactions. Furthermore, the addition of nitrogen can improve the wettability of the nylon-based carbon aerogel surface, enhancing its compatibility.

[0016] Furthermore, the nylon particles in step (1) are one or more of nylon 6 particles, nylon 66 particles, nylon 46 particles, and nylon 56 particles.

[0017] Furthermore, in step (1), the mass volume ratio of the nylon particles to the formic acid solution is 1:(12-15) g / ml. A commonly used formic acid aqueous solution can be used, with a formic acid aqueous solution concentration of 80-95 wt%. Nylon has good solubility in formic acid, and the dissolution rate can be increased by heating to fully dissolve the nylon.

[0018] Furthermore, the ultrasonic power in step (1) is 100-200W.

[0019] Furthermore, in step (2), the inert gas is nitrogen; and the low-temperature carbonization time is 3-5 hours.

[0020] Furthermore, in step (3), the oxidant is one of ferric chloride, ammonium persulfate, and potassium persulfate; and the mass ratio of the pyrrole monomer to the oxidant is 1:(0.5-5).

[0021] Furthermore, the standing time in step (3) is 0.5-1 h. By standing, the polyvinyl pyrrolidone is fully dispersed and the low-temperature carbonized powder is modified, so as to promote the uniform dispersion of the pyrrole monomer on the surface and in the pores of the low-temperature carbonized powder.

[0022] Furthermore, in step (3), the reaction temperature is 0-5°C and the reaction time is 8-12h.

[0023] Furthermore, the high temperature carbonization time in step (4) is 1-2 hours. An appropriate carbonization time can ensure that nylon and polypyrrole are fully carbonized to form a more complete carbon structure, thereby improving conductivity.

[0024] In another aspect, the present invention also provides a polypyrrole-modified nylon-based carbon electrode material for fuel cells. The polypyrrole-modified nylon-based carbon electrode material for fuel cells not only has a high specific surface area but also has a high electrical conductivity, and has broad application prospects.

[0025] Beneficial effects:

[0026] The present invention uses a sol-gel method to prepare carbon aerogel. The carbon aerogel has a high specific surface area, excellent pore size distribution, and lightweight properties, which provide great advantages for its application in electrode materials. However, the conductivity of pure carbon aerogel is still insufficient. To this end, the present invention uses conductive polypyrrole to modify it by nitrogen doping. The nitrogen element in the five-membered ring of polypyrrole is the most ideal element for doping nylon-based carbon aerogel. The atomic radii of the two elements are similar, so the lattice of the nylon-based carbon aerogel is destroyed as little as possible during the nitrogen doping process. At the same time, because nitrogen atoms carry lone pairs of electrons, doping into nylon-based carbon aerogel can increase the charge density of the carbon material, forming an n-type semiconductor, thereby increasing the conductivity of the nylon-based carbon aerogel. Nitrogen doping can also create defect sites in the nylon-based carbon aerogel structure, increasing the activity of the carbon material during electrochemical reactions. In addition, the addition of nitrogen can improve the wettability of the nylon-based carbon aerogel surface and enhance its compatibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0028] Figure 1 This is a scanning electron microscope image of the carbon electrode material prepared in Example 10 of the present invention.

[0029] Figure 2 This is a scanning electron microscope image of the carbon electrode material prepared in Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the described embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. Unless otherwise defined, the technical terms or scientific terms used herein should be the common meanings understood by people with ordinary skills in the field to which the present invention belongs.

[0031] Example 1

[0032] A method for preparing a carbon electrode material for a polypyrrole-modified nylon-based fuel cell comprises the following steps:

[0033] (1) Nylon particles were added to a formic acid solution, ultrasonically dispersed, and then freeze-dried to prepare nylon aerogel; the nylon particles were nylon 66 particles; the mass volume ratio of nylon particles to formic acid solution was 1:14 g / ml; the concentration of formic acid solution was 88 wt%; and the ultrasonic power was 120 W.

[0034] (2) Under nitrogen gas conditions, the nylon aerogel was carbonized at a low temperature of 500°C and a low temperature carbonization time of 5 hours;

[0035] (3) The low-temperature carbonized nylon aerogel was ground and crushed to obtain a low-temperature carbonized powder. The low-temperature carbonized powder and polyvinyl pyrrolidone were first uniformly dispersed in deionized water, allowed to stand for 0.5 h, and then pyrrole monomer was added dropwise to obtain a mixed solution. Under stirring conditions, an aqueous solution containing ammonium persulfate oxidant was added dropwise to the mixed solution, and the mixture was reacted for a period of time to obtain a polypyrrole-modified low-temperature carbonized powder. The mass ratio of the low-temperature carbonized powder to polyvinyl pyrrolidone and pyrrole monomer was 1:0.1:0.03; the number average molecular weight of polyvinyl pyrrolidone was 30,000; the mass ratio of pyrrole monomer to oxidant was 1:2.8; the reaction temperature was 0°C, and the reaction time was 8 h.

[0036] (4) The polypyrrole-modified low-temperature carbonized powder was subjected to high-temperature carbonization under nitrogen protection at a temperature of 950°C to obtain a polypyrrole-modified nylon-based fuel cell carbon electrode material; the high-temperature carbonization time was 2 hours. The specific surface area and conductivity of the carbon electrode material were tested using the BET method and a conductivity tester. The specific surface area was 1567 m 2 g -1 , the conductivity is 12.3Scm -1 .

[0037] Example 2

[0038] A method for preparing a carbon electrode material for a polypyrrole-modified nylon-based fuel cell comprises the following steps:

[0039] (1) Nylon particles were added to a formic acid solution, ultrasonically dispersed, and then freeze-dried to prepare nylon aerogel; the nylon particles were nylon 66 particles; the mass volume ratio of nylon particles to formic acid solution was 1:14 g / ml; the concentration of formic acid solution was 88 wt%; and the ultrasonic power was 200 W;

[0040] (2) Under nitrogen gas conditions, the nylon aerogel was carbonized at a low temperature of 600°C and a low temperature carbonization time of 3 hours;

[0041] (3) The low-temperature carbonized nylon aerogel was ground and crushed to obtain a low-temperature carbonized powder. The low-temperature carbonized powder and polyvinyl pyrrolidone were first uniformly dispersed in deionized water, allowed to stand for 1 hour, and then pyrrole monomer was added dropwise to obtain a mixed solution. Under stirring conditions, an aqueous solution containing ammonium persulfate oxidant was added dropwise to the mixed solution, and the mixture was reacted for a period of time to obtain a polypyrrole-modified low-temperature carbonized powder. The mass ratio of the low-temperature carbonized powder to polyvinyl pyrrolidone and pyrrole monomer was 1:0.3:0.3; the number average molecular weight of polyvinyl pyrrolidone was 30,000; the mass ratio of pyrrole monomer to oxidant was 1:3.3; the reaction temperature was 0°C, and the reaction time was 12 hours.

[0042] (4) The polypyrrole-modified low-temperature carbonized powder was subjected to high-temperature carbonization under nitrogen protection at a temperature of 1080°C to obtain a polypyrrole-modified nylon-based fuel cell carbon electrode material; the high-temperature carbonization time was 1 hour. The specific surface area and conductivity of the carbon electrode material were tested using the BET method and a conductivity tester. The specific surface area was 1486 m 2 g -1 , the conductivity is 22.3Scm -1 .

[0043] Example 3

[0044] A method for preparing a carbon electrode material for a polypyrrole-modified nylon-based fuel cell comprises the following steps:

[0045] (1) Nylon particles were added to a formic acid solution, ultrasonically dispersed, and then freeze-dried to prepare nylon aerogel; the nylon particles were nylon 66 particles; the mass volume ratio of nylon particles to formic acid solution was 1:14 g / ml; the concentration of formic acid solution was 88 wt%; and the ultrasonic power was 150 W.

[0046] (2) The nylon aerogel was carbonized at a low temperature of 560°C under nitrogen gas conditions and for 4 hours.

[0047] (3) The low-temperature carbonized nylon aerogel was ground and crushed to obtain a low-temperature carbonized powder. The low-temperature carbonized powder and polyvinyl pyrrolidone were first uniformly dispersed in deionized water, allowed to stand for 0.7 h, and then pyrrole monomer was added dropwise to obtain a mixed solution. Under stirring conditions, an aqueous solution containing ammonium persulfate oxidant was added dropwise to the mixed solution, and the mixture was reacted for a period of time to obtain a polypyrrole-modified low-temperature carbonized powder. The mass ratio of the low-temperature carbonized powder to polyvinyl pyrrolidone and pyrrole monomer was 1:0.05:0.2; the number average molecular weight of polyvinyl pyrrolidone was 30,000; the mass ratio of pyrrole monomer to oxidant was 1:3; the reaction temperature was 0°C, and the reaction time was 10 h.

[0048] (4) The polypyrrole-modified low-temperature carbonized powder was subjected to high-temperature carbonization under nitrogen protection at a temperature of 1020°C to obtain a polypyrrole-modified nylon-based fuel cell carbon electrode material; the high-temperature carbonization time was 1.5 hours. The specific surface area and conductivity of the carbon electrode material were tested using the BET method and a conductivity tester. The specific surface area was 1416 m 2 g -1 , conductivity is 17.5Scm -1 .

[0049] Example 4

[0050] A method for preparing a carbon electrode material for a polypyrrole-modified nylon-based fuel cell comprises the following steps:

[0051] (1) Nylon particles were added to a formic acid solution, ultrasonically dispersed, and then freeze-dried to prepare nylon aerogel; the nylon particles were nylon 66 particles; the mass volume ratio of nylon particles to formic acid solution was 1:14 g / ml; the concentration of formic acid solution was 88 wt%; and the ultrasonic power was 160 W.

[0052] (2) The nylon aerogel was subjected to low-temperature carbonization under nitrogen gas conditions, with the low-temperature carbonization temperature being 500°C and the low-temperature carbonization time being 4.5 hours;

[0053] (3) The low-temperature carbonized nylon aerogel was ground and crushed to obtain a low-temperature carbonized powder. The low-temperature carbonized powder and polyvinyl pyrrolidone were first uniformly dispersed in deionized water, allowed to stand for 1 hour, and then pyrrole monomer was added dropwise to obtain a mixed solution. Under stirring conditions, an aqueous solution containing ammonium persulfate oxidant was added dropwise to the mixed solution, and the mixture was reacted for a period of time to obtain a polypyrrole-modified low-temperature carbonized powder. The mass ratio of the low-temperature carbonized powder to polyvinyl pyrrolidone and pyrrole monomer was 1:0.1:0.3; the number average molecular weight of polyvinyl pyrrolidone was 30,000; the mass ratio of pyrrole monomer to oxidant was 1:2.9; the reaction temperature was 0°C, and the reaction time was 12 hours.

[0054] (4) The polypyrrole-modified low-temperature carbonized powder was subjected to high-temperature carbonization under nitrogen protection at a temperature of 950°C to obtain a polypyrrole-modified nylon-based fuel cell carbon electrode material; the high-temperature carbonization time was 1 hour. The specific surface area and conductivity of the carbon electrode material were tested using the BET method and a conductivity tester. The specific surface area was 1453 m 2 g -1 , the conductivity is 16.2Scm -1 .

[0055] Example 5

[0056] A method for preparing a carbon electrode material for a polypyrrole-modified nylon-based fuel cell comprises the following steps:

[0057] (1) Nylon particles were added to a formic acid solution, ultrasonically dispersed, and then freeze-dried to prepare nylon aerogel; the nylon particles were nylon 66 particles; the mass volume ratio of nylon particles to formic acid solution was 1:14 g / ml; the concentration of formic acid solution was 88 wt%; and the ultrasonic power was 150 W.

[0058] (2) The nylon aerogel was carbonized at a low temperature of 560°C under nitrogen gas conditions and for 4 hours.

[0059] (3) The low-temperature carbonized nylon aerogel was ground and crushed to obtain a low-temperature carbonized powder. The low-temperature carbonized powder and polyvinyl pyrrolidone were first uniformly dispersed in deionized water and allowed to stand for 0.7 h. Then, pyrrole monomer was added dropwise to obtain a mixed solution. Under stirring, an aqueous solution containing ammonium persulfate oxidant was added dropwise to the mixed solution. The mixture was reacted for a period of time to obtain a polypyrrole-modified low-temperature carbonized powder. The mass ratio of the low-temperature carbonized powder to polyvinyl pyrrolidone and pyrrole monomer was 1:0.35:0.2. The number average molecular weight of polyvinyl pyrrolidone was 30,000. The mass ratio of pyrrole monomer to oxidant was 1:3. The reaction temperature was 0°C and the reaction time was 10 h.

[0060] (4) The polypyrrole-modified low-temperature carbonized powder was subjected to high-temperature carbonization under nitrogen protection at a temperature of 1020°C to obtain a polypyrrole-modified nylon-based fuel cell carbon electrode material; the high-temperature carbonization time was 1.5 hours. The specific surface area and conductivity of the carbon electrode material were tested using the BET method and a conductivity tester. The specific surface area was 1431 m 2 g -1 , the conductivity is 16.7Scm -1 .

[0061] Example 6

[0062] A method for preparing a carbon electrode material for a polypyrrole-modified nylon-based fuel cell comprises the following steps:

[0063] (1) Nylon particles were added to a formic acid solution, ultrasonically dispersed, and then freeze-dried to prepare nylon aerogel; the nylon particles were nylon 66 particles; the mass volume ratio of nylon particles to formic acid solution was 1:14 g / ml; the concentration of formic acid solution was 88 wt%; and the ultrasonic power was 140 W.

[0064] (2) The nylon aerogel was carbonized at a low temperature of 520°C under nitrogen gas conditions and for 4.2 h.

[0065] (3) The low-temperature carbonized nylon aerogel was ground and pulverized to obtain low-temperature carbonized powder. The low-temperature carbonized powder and polyvinyl pyrrolidone were first uniformly dispersed in deionized water and allowed to stand for 0.6 h. Then, pyrrole monomer was added dropwise to obtain a mixed solution. Under stirring, an aqueous solution containing ammonium persulfate oxidant was added dropwise to the mixed solution. The mixture was reacted for a period of time to obtain polypyrrole-modified low-temperature carbonized powder. The mass ratio of low-temperature carbonized powder to polyvinyl pyrrolidone and pyrrole monomer was 1:0.14:0.12. The number average molecular weight of polyvinyl pyrrolidone was 30,000. The mass ratio of pyrrole monomer to oxidant was 1:2.9. The reaction temperature was 0°C and the reaction time was 9 h.

[0066] (4) The polypyrrole-modified low-temperature carbonized powder was subjected to high-temperature carbonization under nitrogen protection at a temperature of 980°C to obtain a polypyrrole-modified nylon-based fuel cell carbon electrode material; the high-temperature carbonization time was 1.8 hours. The specific surface area and conductivity of the carbon electrode material were tested using the BET method and a conductivity tester. The specific surface area was 1512 m 2 g -1 , the conductivity is 15.8Scm -1 .

[0067] Example 7

[0068] A method for preparing a carbon electrode material for a polypyrrole-modified nylon-based fuel cell comprises the following steps:

[0069] (1) Nylon particles were added to a formic acid solution, ultrasonically dispersed, and then freeze-dried to prepare nylon aerogel; the nylon particles were nylon 66 particles; the mass volume ratio of nylon particles to formic acid solution was 1:14 g / ml; the concentration of formic acid solution was 88 wt%; and the ultrasonic power was 150 W.

[0070] (2) The nylon aerogel was carbonized at a low temperature of 560°C under nitrogen gas conditions and for 4 hours.

[0071] (3) The low-temperature carbonized nylon aerogel was ground and crushed to obtain a low-temperature carbonized powder. The low-temperature carbonized powder and polyvinyl pyrrolidone were first uniformly dispersed in deionized water, allowed to stand for 0.7 h, and then pyrrole monomer was added dropwise to obtain a mixed solution. Under stirring conditions, an aqueous solution containing ammonium persulfate oxidant was added dropwise to the mixed solution, and the mixture was reacted for a period of time to obtain a polypyrrole-modified low-temperature carbonized powder. The mass ratio of the low-temperature carbonized powder to polyvinyl pyrrolidone and pyrrole monomer was 1:0.2:0.2; the number average molecular weight of polyvinyl pyrrolidone was 30,000; the mass ratio of pyrrole monomer to oxidant was 1:3; the reaction temperature was 0°C, and the reaction time was 10 h.

[0072] (4) The polypyrrole-modified low-temperature carbonized powder was subjected to high-temperature carbonization under nitrogen protection at a temperature of 1150°C to obtain a polypyrrole-modified nylon-based fuel cell carbon electrode material; the high-temperature carbonization time was 1.5 hours. The specific surface area and conductivity of the carbon electrode material were tested using the BET method and a conductivity tester. The specific surface area was 1467 m 2 g -1 , the conductivity is 23.9Scm -1 .

[0073] Example 8

[0074] A method for preparing a carbon electrode material for a polypyrrole-modified nylon-based fuel cell comprises the following steps:

[0075] (1) Nylon particles were added to a formic acid solution, ultrasonically dispersed, and then freeze-dried to prepare nylon aerogel; the nylon particles were nylon 66 particles; the mass volume ratio of nylon particles to formic acid solution was 1:14 g / ml; the concentration of formic acid solution was 88 wt%; and the ultrasonic power was 180 W;

[0076] (2) Under nitrogen gas conditions, the nylon aerogel was carbonized at a low temperature of 580°C and a low temperature carbonization time of 3.5 hours;

[0077] (3) The low-temperature carbonized nylon aerogel was ground and crushed to obtain a low-temperature carbonized powder. The low-temperature carbonized powder and polyvinyl pyrrolidone were first uniformly dispersed in deionized water and allowed to stand for 0.8 h. Then, pyrrole monomer was added dropwise to obtain a mixed solution. Under stirring, an aqueous solution containing ammonium persulfate oxidant was added dropwise to the mixed solution. The mixture was reacted for a period of time to obtain a polypyrrole-modified low-temperature carbonized powder. The mass ratio of the low-temperature carbonized powder to polyvinyl pyrrolidone and pyrrole monomer was 1:0.25:0.26. The number average molecular weight of polyvinyl pyrrolidone was 30,000. The mass ratio of pyrrole monomer to oxidant was 1:3.1. The reaction temperature was 0°C and the reaction time was 11 h.

[0078] (4) The polypyrrole-modified low-temperature carbonized powder was subjected to high-temperature carbonization under nitrogen protection at a temperature of 1050°C to obtain a polypyrrole-modified nylon-based fuel cell carbon electrode material; the high-temperature carbonization time was 1.3 hours. The specific surface area and conductivity of the carbon electrode material were tested using the BET method and a conductivity tester. The specific surface area was 1522 m 2 g -1 , the conductivity is 18.6Scm -1 .

[0079] Example 9

[0080] A method for preparing a carbon electrode material for a polypyrrole-modified nylon-based fuel cell comprises the following steps:

[0081] (1) Nylon particles were added to a formic acid solution, ultrasonically dispersed, and then freeze-dried to prepare nylon aerogel; the nylon particles were nylon 66 particles; the mass volume ratio of nylon particles to formic acid solution was 1:14 g / ml; the concentration of formic acid solution was 88 wt%; and the ultrasonic power was 130 W.

[0082] (2) The nylon aerogel was carbonized at a low temperature of 530°C under nitrogen gas conditions and for a period of 4.1 h.

[0083] (3) The low-temperature carbonized nylon aerogel was ground and pulverized to obtain low-temperature carbonized powder. The low-temperature carbonized powder and polyvinyl pyrrolidone were first uniformly dispersed in deionized water and allowed to stand for 0.9 h. Then, pyrrole monomer was added dropwise to obtain a mixed solution. Under stirring conditions, an aqueous solution containing ammonium persulfate oxidant was added dropwise to the mixed solution. The mixture was reacted for a period of time to obtain polypyrrole-modified low-temperature carbonized powder. The mass ratio of low-temperature carbonized powder to polyvinyl pyrrolidone and pyrrole monomer was 1:0.16:0.22. The number average molecular weight of polyvinyl pyrrolidone was 30,000. The mass ratio of pyrrole monomer to oxidant was 1:2.8. The reaction temperature was 0°C and the reaction time was 9.5 h.

[0084] (4) The polypyrrole-modified low-temperature carbonized powder was subjected to high-temperature carbonization under nitrogen protection at a temperature of 1020°C to obtain a polypyrrole-modified nylon-based fuel cell carbon electrode material; the high-temperature carbonization time was 1.3 hours. The specific surface area and conductivity of the carbon electrode material were tested using the BET method and a conductivity tester, and the specific surface area was 1487 m 2 g -1 , the conductivity is 20.7Scm -1 .

[0085] Example 10

[0086] A method for preparing a carbon electrode material for a polypyrrole-modified nylon-based fuel cell comprises the following steps:

[0087] (1) Nylon particles were added to a formic acid solution, ultrasonically dispersed, and then freeze-dried to prepare nylon aerogel; the nylon particles were nylon 66 particles; the mass volume ratio of nylon particles to formic acid solution was 1:14 g / ml; the concentration of formic acid solution was 88 wt%; and the ultrasonic power was 150 W.

[0088] (2) The nylon aerogel was carbonized at a low temperature of 560°C under nitrogen gas conditions and for 4 hours.

[0089] (3) The low-temperature carbonized nylon aerogel was ground and crushed to obtain a low-temperature carbonized powder. The low-temperature carbonized powder and polyvinyl pyrrolidone were first uniformly dispersed in deionized water, allowed to stand for 0.7 h, and then pyrrole monomer was added dropwise to obtain a mixed solution. Under stirring conditions, an aqueous solution containing ammonium persulfate oxidant was added dropwise to the mixed solution, and the mixture was reacted for a period of time to obtain a polypyrrole-modified low-temperature carbonized powder. The mass ratio of the low-temperature carbonized powder to polyvinyl pyrrolidone and pyrrole monomer was 1:0.2:0.2; the number average molecular weight of polyvinyl pyrrolidone was 30,000; the mass ratio of pyrrole monomer to oxidant was 1:3; the reaction temperature was 0°C, and the reaction time was 10 h.

[0090] (4) The polypyrrole-modified low-temperature carbonized powder was subjected to high-temperature carbonization under nitrogen protection at a temperature of 1020°C to obtain a polypyrrole-modified nylon-based fuel cell carbon electrode material; the high-temperature carbonization time was 1.5 hours. The specific surface area and conductivity of the carbon electrode material were tested using the BET method and a conductivity tester. The specific surface area was 1577 m 2 g -1 , the conductivity is 24.1Scm -1 .

[0091] Comparative Example 1

[0092] A method for preparing a carbon electrode material for a polypyrrole-modified nylon-based fuel cell comprises the following steps:

[0093] (1) Nylon particles were added to a formic acid solution, ultrasonically dispersed, and then freeze-dried to prepare nylon aerogel; the nylon particles were nylon 66 particles; the mass volume ratio of nylon particles to formic acid solution was 1:14 g / ml; the concentration of formic acid solution was 88 wt%; and the ultrasonic power was 150 W.

[0094] (2) The nylon aerogel was carbonized at a low temperature of 560°C under nitrogen gas conditions and for 4 hours.

[0095] (3) The low-temperature carbonized nylon aerogel was ground and crushed to obtain low-temperature carbonized powder. The low-temperature carbonized powder was first evenly dispersed in deionized water and allowed to stand for 0.7 h. Then, pyrrole monomer was added dropwise, and polyvinyl pyrrolidone was added. After stirring, a mixed solution was obtained. Under stirring, an aqueous solution containing ammonium persulfate oxidant was added dropwise to the mixed solution. The mixture was reacted for a period of time to obtain polypyrrole-modified low-temperature carbonized powder. The mass ratio of low-temperature carbonized powder to polyvinyl pyrrolidone and pyrrole monomer was 1:0.2:0.2. The number average molecular weight of polyvinyl pyrrolidone was 30,000. The mass ratio of pyrrole monomer to oxidant was 1:3. The reaction temperature was 0°C and the reaction time was 10 h.

[0096] (4) The polypyrrole-modified low-temperature carbonized powder was subjected to high-temperature carbonization under nitrogen protection at a temperature of 1020°C to obtain a polypyrrole-modified nylon-based fuel cell carbon electrode material; the high-temperature carbonization time was 1.5 hours. The specific surface area and conductivity of the carbon electrode material were tested using the BET method and a conductivity tester. The specific surface area was 1205 m 2 g -1 , the conductivity is 5.7Scm -1 .

[0097] Comparative Example 2

[0098] A method for preparing a carbon electrode material for a polypyrrole-modified nylon-based fuel cell comprises the following steps:

[0099] (1) Nylon particles were added to a formic acid solution, ultrasonically dispersed, and then freeze-dried to prepare nylon aerogel; the nylon particles were nylon 66 particles; the mass volume ratio of nylon particles to formic acid solution was 1:14 g / ml; the concentration of formic acid solution was 88 wt%; and the ultrasonic power was 150 W.

[0100] (2) Grind the nylon aerogel to obtain aerogel powder, first evenly disperse the aerogel powder and polyvinyl pyrrolidone in deionized water, let it stand for 0.7 h, and then add pyrrole monomer to obtain a mixed solution; under stirring, add an aqueous solution containing ammonium persulfate oxidant to the mixed solution, react for a period of time, and obtain polypyrrole-modified aerogel powder; the mass ratio of aerogel powder to polyvinyl pyrrolidone and pyrrole monomer is 1:0.2:0.2; the number average molecular weight of polyvinyl pyrrolidone is 30,000; the mass ratio of pyrrole monomer to oxidant is 1:3; the reaction temperature is 0°C, and the reaction time is 10 h;

[0101] (4) The polypyrrole-modified aerogel powder was carbonized at a temperature of 1020°C under nitrogen protection to obtain a polypyrrole-modified nylon-based fuel cell carbon electrode material; the high-temperature carbonization time was 1.5 hours. The specific surface area and conductivity of the carbon electrode material were tested using the BET method and a conductivity tester. The specific surface area was 1137 m 2 g -1 , the conductivity is 6.2Scm -1 .

[0102] Comparative Example 3

[0103] A method for preparing a carbon electrode material for a polypyrrole-modified nylon-based fuel cell comprises the following steps:

[0104] (1) Nylon particles were added to a formic acid solution, ultrasonically dispersed, and then freeze-dried to prepare nylon aerogel; the nylon particles were nylon 66 particles; the mass volume ratio of nylon particles to formic acid solution was 1:14 g / ml; the concentration of formic acid solution was 88 wt%; and the ultrasonic power was 150 W.

[0105] (2) The nylon aerogel was carbonized at a low temperature of 560°C under nitrogen gas conditions and for 4 hours.

[0106] (3) The low-temperature carbonized nylon aerogel was ground and crushed to obtain a low-temperature carbonized powder. The low-temperature carbonized powder and polyvinyl pyrrolidone were first uniformly dispersed in deionized water, allowed to stand for 0.7 h, and then pyrrole monomer was added dropwise to obtain a mixed solution. Under stirring conditions, an aqueous solution containing ammonium persulfate oxidant was added dropwise to the mixed solution, and the mixture was reacted for a period of time to obtain a polypyrrole-modified low-temperature carbonized powder. The mass ratio of the low-temperature carbonized powder to polyvinyl pyrrolidone and pyrrole monomer was 1:0.2:0.5; the number average molecular weight of polyvinyl pyrrolidone was 30,000; the mass ratio of pyrrole monomer to oxidant was 1:3; the reaction temperature was 0°C, and the reaction time was 10 h.

[0107] (4) The polypyrrole-modified low-temperature carbonized powder was subjected to high-temperature carbonization under nitrogen protection at a temperature of 1020°C to obtain a polypyrrole-modified nylon-based fuel cell carbon electrode material; the high-temperature carbonization time was 1.5 hours. The specific surface area and conductivity of the carbon electrode material were tested using the BET method and a conductivity tester. The specific surface area was 1086 m 2 g -1 , conductivity is 7.5Scm -1 .

[0108] As can be seen from the above embodiments and comparative examples, the present invention adopts the sol-gel method to prepare carbon aerogel. The carbon aerogel has a high specific surface area and lightweight properties, which provide great advantages for its application in electrode materials. Conductive polypyrrole is used to carry out nitrogen doping modification. The nitrogen element in the five-membered ring of polypyrrole is the most ideal element for doping nylon-based carbon aerogel. The atomic radius of the two elements is similar, so the lattice of the nylon-based carbon aerogel is destroyed as little as possible during the nitrogen doping process. At the same time, since nitrogen atoms carry lone pairs of electrons, doping into nylon-based carbon aerogel can increase the charge density of the carbon material, forming an n-type semiconductor, thereby increasing the conductivity of the nylon-based carbon aerogel. The doping of nitrogen can cause defect sites in the structure of the nylon-based carbon aerogel, thereby improving the activity of the carbon material during the electrochemical reaction.

[0109] Depend on Figure 1It can be seen that the electrode material prepared by the present invention has a rich pore structure, the gel morphology remains relatively intact after high-temperature carbonization, the carbonized polypyrrole is evenly distributed on the surface of the low-temperature carbonized powder, no agglomerated particles or large-scale collapse are seen, and the surface area is large. Compared with Example 10, Comparative Example 1 did not mix polyvinyl pyrrolidone with the low-temperature carbonized powder in advance. Figure 2 It can be seen that the porous structure of Comparative Example 1 is destroyed, and large-scale agglomeration of carbonized polypyrrole occurs, which leads to the appearance of a blocking structure and a significant reduction in specific surface area. This is because polyvinyl pyrrolidone plays the dual role of a dispersant and a template agent. It needs to be lifted and mixed with the low-temperature carbonized powder to promote the uniform dispersion of polypyrrole on the surface and in the pores of the low-temperature carbonized powder. Comparative Example 1 does not mix polyvinyl pyrrolidone with the low-temperature carbonized powder in advance, which cannot promote the dispersion of the powder. The carbonized polypyrrole has poor dispersibility, not only agglomeration occurs, blocking the porous structure of the carbonized gel powder, but also it cannot play a reinforcing role. The pore wall collapses during the high-temperature carbonization process, and the specific surface area is reduced. Combined with the relevant data, it can be seen that the uncarbonized nylon-based aerogel of Comparative Example 2 has poor affinity with polyvinyl pyrrolidone and pyrrole monomer, which affects the in-situ polymerization reaction of pyrrole monomer. The polypyrrole has poor dispersibility, which affects the nitrogen doping process, resulting in a reduction in the specific surface area and conductivity of the carbon electrode material. It can be seen from Comparative Example 3 that when the amount of pyrrole monomer used as a doping modifier is too much, it may also cause agglomeration, resulting in the destruction of the porous structure of the powder, resulting in a decrease in specific surface area, affecting the construction of the conductive path, and reducing the conductivity.

[0110] 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 of the present invention 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 carbon electrode material for a polypyrrole-modified nylon-based fuel cell, characterized in that: The following steps are involved: (1) Nylon particles were added to a formic acid solution, dispersed evenly by ultrasonication, and then freeze-dried to prepare nylon aerogel; (2) Under inert gas conditions, the nylon aerogel is carbonized at a low temperature of 500-600°C; (3) The low-temperature carbonized nylon aerogel is ground and pulverized to obtain a low-temperature carbonized powder. The low-temperature carbonized powder and polyvinyl pyrrolidone are first uniformly dispersed in deionized water, allowed to stand for a period of time, and then pyrrole monomer is added dropwise to obtain a mixed solution; an aqueous solution containing an oxidant is added dropwise to the mixed solution under stirring, and the mixture is reacted for a period of time to obtain a polypyrrole-modified low-temperature carbonized powder; the mass ratio of the low-temperature carbonized powder to polyvinyl pyrrolidone and pyrrole monomer is 1: (0.05-0.35): (0.01-0.3); (4) The polypyrrole-modified low-temperature carbonized powder is subjected to high-temperature carbonization under the protection of an inert gas, and the high-temperature carbonization temperature is 950-1150°C, thereby obtaining a polypyrrole-modified nylon-based carbon electrode material for a fuel cell.

2. The method for preparing a carbon electrode material for a polypyrrole-modified nylon-based fuel cell according to claim 1, wherein: The nylon particles in step (1) are one or more of nylon 6 particles, nylon 66 particles, nylon 46 particles, and nylon 56 particles.

3. The method for preparing a polypyrrole-modified nylon-based fuel cell carbon electrode material according to claim 1, wherein: In step (1), the mass volume ratio of nylon particles to formic acid solution is 1: (12-15) g / ml; and the concentration of formic acid solution is 80-95 wt%.

4. The method for preparing a polypyrrole-modified nylon-based fuel cell carbon electrode material according to claim 1, wherein: The ultrasonic power in step (1) is 100-200W.

5. The method for preparing a polypyrrole-modified nylon-based fuel cell carbon electrode material according to claim 1, wherein: In step (2), the inert gas is nitrogen; and the low-temperature carbonization time is 3-5 hours.

6. The method for preparing a carbon electrode material for a polypyrrole-modified nylon-based fuel cell according to claim 1, wherein: In step (3), the oxidant is one of ferric chloride, ammonium persulfate, and potassium persulfate; and the mass ratio of the pyrrole monomer to the oxidant is 1:(0.5-5).

7. The method for preparing a polypyrrole-modified nylon-based fuel cell carbon electrode material according to claim 1, wherein: The standing time in step (3) is 0.5-1h.

8. The method for preparing a carbon electrode material for a polypyrrole-modified nylon-based fuel cell according to claim 1, wherein: In step (3), the reaction temperature is 0-5°C and the reaction time is 8-12h.

9. The method for preparing a polypyrrole-modified nylon-based fuel cell carbon electrode material according to claim 1, wherein: The high temperature carbonization time in step (4) is 1-2 hours.

10. A polypyrrole-modified nylon-based carbon electrode material for a fuel cell, characterized in that: The carbon electrode material is prepared by the method for preparing a polypyrrole-modified nylon-based fuel cell according to any one of claims 1 to 9.

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