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

Abstract

The present invention belongs to the technical field of fuel cell electrode material preparation, and specifically relates to a polypyrrole-modified carbon electrode material for bio-based fuel cells and a preparation method thereof. The method comprises the following steps: sequentially modifying rice husk low-temperature carbonization powder using a unipolar functional group POSS and a multipolar functional group POSS to obtain a modified low-temperature carbonization powder; in situ polymerizing pyrrole monomer on the surface of the modified low-temperature carbonization powder, and subjecting the modified low-temperature carbonization powder to high-temperature carbonization and hydrofluoric acid corrosion to obtain a polypyrrole-modified carbon electrode material for bio-based fuel cells. The multipolar functional group POSS not only facilitates the in-situ polymerization reaction of pyrrole, but also forms a continuous macromolecular chain and a network structure on the entire material surface. The unipolar functional group POSS not only improves the stability of the low-temperature carbonization powder during the high-temperature carbonization process, but more importantly, provides a channel for subsequent hydrofluoric acid corrosion, etches away non-conductive substances, and increases the electrical conductivity and specific surface area of ​​the carbon electrode material.

Description

Technical Field

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

[0002] Fuel cells are power generation devices that directly convert the chemical energy of small molecule fuels and oxidants into electricity for human consumption. As a next-generation power generation technology, they offer advantages such as high energy conversion efficiency, low pollution, a wide range of raw materials, high specific capacity, and stable operation. Because they are not constrained by the Carnot cycle, the second law of thermodynamics, fuel cells can achieve conversion efficiencies of 40-60% (the remainder is converted into heat for heating), and in combined heat and power systems, efficiency can reach over 85%. The reaction products of small molecule fuels with oxygen / air contain no pollutants such as sulfur oxides, nitrogen oxides, or dust, making them environmentally friendly. Fuel cells utilize a wide variety of small molecule fuels. Hydrogen is the most widely available, coming from sources such as water electrolysis, industrial byproduct recovery, and fossil feedstock production. Compared to lithium-ion batteries, fuel cells, as power generation devices, have a significantly higher upper limit on energy (power) density. Unlike conventional batteries, fuel cells deliver stable power output as long as fuel is supplied, can operate under overload or below rated capacity, and offer rapid response times. Compared to the multi-step processes involved in combustion-based heat engines, fuel cells offer the advantage of compatibility with renewable energy and modern energy carriers, enabling sustainable energy development and environmental protection. Furthermore, fuel cells offer advantages such as silent operation, simple structure, and ease of transport. Therefore, fuel cells are a highly promising energy conversion device with broad prospects for commercial application.

[0003] As a key component of fuel cells, the type of electrode material directly affects their performance. Carbon-based materials are the most widely used electrode materials. Commonly used carbon-based materials include graphite sheets, carbon cloth, carbon paper, and carbon felt. They have good electrical conductivity and chemical stability. However, these materials require expensive raw materials, and most preparation processes are complex. They also have small specific surface areas, and some materials have limited electrochemical reaction active sites, resulting in limited active surface area and conductivity. Summary of the Invention

[0004] The present invention aims to provide a polypyrrole-modified carbon electrode material for bio-based fuel cells and a method for preparing the same. This polypyrrole-modified carbon electrode material for bio-based fuel cells, made from rice husks, is not only environmentally friendly but also exhibits a high specific surface area and electrical conductivity, resolving the challenges associated with existing carbon electrode materials.

[0005] Electrode materials play an important role in improving the performance of fuel cells, and selecting suitable electrode materials is the key to improving the performance of fuel cells. Ideal fuel cell electrode materials should have high specific surface area, porosity, high conductivity and mechanical strength. The speed at which electrons are transferred to the electrode and the electrochemical properties of the material will limit the power output of the fuel cell. In order to improve the efficiency of the fuel cell and the conductivity of the electrode, various types of metal materials are used to modify the electrode, but the high cost severely limits their application in fuel cell electrode materials. Traditional carbon materials have complex preparation processes and high costs. Biomass energy is regarded as a green resource that can replace traditional carbon materials. The present invention uses rice husks as a source of biomass carbon. The utilization of rice husk biomass carbon can reduce the waste of some resources, alleviate some of the impacts of waste treatment on the environment, and achieve environmental improvement and waste recycling.

[0006] Specifically, in order to solve the above problems, the present invention adopts the following technical solutions:

[0007] A method for preparing a polypyrrole-modified carbon electrode material for a bio-based fuel cell comprises the following steps:

[0008] (1) The rice husk is subjected to low-temperature carbonization and then ground to obtain low-temperature carbonized powder; the low-temperature carbonization temperature is 400-550°C; the rice husk is clean rice husk that has been washed, dried and dehydrated; this step firstly carbonizes the rice husk at low temperature to remove inert substances on its surface, and at the same time, the rice husk is initially carbonized through the low-temperature carbonization process, which not only forms primary carbonized materials containing various oxygen-containing functional groups on its surface, but also forms fine pores, which can load POSS containing polar functional groups by utilizing chemical bonds and its own capillary adsorption capacity.

[0009] (2) firstly modifying the low-temperature carbonization powder with a unipolar functional group-containing POSS to obtain a primary modified low-temperature carbonization powder; then modifying the primary modified low-temperature carbonization powder again with a multipolar functional group-containing POSS to obtain a modified low-temperature carbonization powder; the number of polar functional groups on the multipolar functional group-containing POSS is greater than 4; the mass ratio of the low-temperature carbonization powder to the unipolar functional group-containing POSS is 1:(0.01-0.1); the mass ratio of the low-temperature carbonization powder to the multipolar functional group-containing POSS is 1:(0.1-0.4);

[0010] (3) dispersing the modified low-temperature carbonized powder in deionized water, and then adding pyrrole monomer and an aqueous solution containing an oxidant dropwise to obtain polypyrrole modified low-temperature carbonized powder after reaction;

[0011] (4) The polypyrrole modified low-temperature carbonization powder is carbonized at high temperature, and after being corroded by hydrofluoric acid solution, cleaned and dried, a polypyrrole modified carbon electrode material for bio-based fuel cells is obtained; the temperature of high-temperature carbonization is 900-1200°C. Polypyrrole has a relatively low cost among many conductive polymers and a simple preparation process. More importantly, the pyrrole ring in its structure can better improve the performance of carbon electrode materials as structural nitrogen. The nitrogen element in the five-membered ring of polypyrrole is the most ideal element for doping carbon materials. The atomic radii of the two elements are similar, so the lattice of the carbon material 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 carbon materials can increase the charge density of carbon materials, forming n-type semiconductors, thereby increasing the conductivity of carbon materials. Nitrogen doping can create defect sites in carbon materials and improve the activity of carbon materials in electrochemical reactions. In addition, the addition of nitrogen can improve the wettability of the carbon material surface and improve its compatibility.

[0012] Experimental findings show that rice husk biomass carbon has the advantages of large porosity, large specific surface area, porous structure, strong chemical stability and low charge transfer resistance, making it an ideal carbon material. However, simple rice husk as a source of biochar will inevitably experience structural collapse during high-temperature carbonization, causing destruction of the surface porous structure, easily causing the carbonized polypyrrole to fall off, and is not conducive to improving electrical conductivity. In order to solve the problem of structural destruction during rice husk carbonization, the present invention uses POSS containing different numbers of polar groups to modify it. The POSS specifically used in the present invention is a cage-type hexahedral structure POSS, with a silicon atom on each vertex of the cage, and an organic substituent is connected to this silicon atom. These organic substituents can be inert, such as ethyl, isobutyl, cyclohexyl, etc.; or they can be reactive groups, such as epoxy, amino, etc. The non-reactive functional groups in POSS can be blended with the low-temperature carbonization powder and serve as a carbon source for high-temperature carbonization. The reactive polar functional groups in the POSS not only improve compatibility with the low-temperature carbonization powder but also form chemical bonds, such as hydrogen bonds, with the imine bonds on the pyrrole monomer. Specifically, during solution heating, the polar functional groups of the POSS containing monopolar functional groups readily form bonds with various oxygen-containing functional groups (such as carboxyl and hydroxyl groups) on the low-temperature carbonization powder, improving the hydrophilic and hydrophobic properties of the low-temperature carbonization powder surface. The reason for first modifying the low-temperature carbonization powder with POSS containing monopolar functional groups is that POSS containing monopolar functional groups has fewer polar groups and, therefore, has poor affinity with the low-temperature carbonization powder. If POSS containing multipolar functional groups is added first, or if both POSS containing monopolar functional groups and POSS containing multipolar functional groups are added simultaneously, the multipolar POSS, with its higher number of polar groups, is more likely to form hydrogen bonds or react with oxygen-containing functional groups on the low-temperature carbonized powder. Due to differences in reactivity and the substantial steric hindrance of POSS, the preferential attachment of the multipolar POSS can affect the bonding between the monopolar POSS and the low-temperature carbonized powder, hindering its attachment and uniform dispersion. As a biomass material, rice husk shrinks during high-temperature carbonization, leading to a collapse of its porous structure and a decrease in specific surface area. However, the intermediate POSS (with a polypyrrole exterior) forms an inorganic network containing silicon oxides, such as silica, upon high-temperature carbonization. This structure exhibits superior mechanical properties, effectively preventing volume shrinkage of the low-temperature carbonized powder during high-temperature carbonization and improving its high-temperature stability. After high-temperature carbonization is completed, silicon oxides such as silicon dioxide formed after POSS carbonization can be removed by hydrofluoric acid corrosion, thereby increasing the porosity and surface area of ​​the bio-based carbon material.

[0013] The unipolar functional group POSS and the multipolar functional group POSS are different in the effect played by the present invention. Specifically, POSS itself is a non-polar cage molecule, is connected with the low-temperature carbonized powder containing the unipolar functional group POSS one end, and the other end presents hydrophobicity, prevents the load of pyrrole monomer. This is because, if the low-temperature carbonized powder or surface POSS are all covered by the pyrrole monomer, carbonized polypyrrole can be fully covered on the low-temperature carbonized powder and POSS (be transformed into oxides such as silicon dioxide after the high-temperature carbonization) surface after the high-temperature carbonization, carbonized polypyrrole can hinder the corrosion of hydrofluoric acid to oxides such as silicon dioxide, as non-conductive substance, the existence of silicon dioxide can not only improve the resistivity of carbon electrode material, and can cause the carbon electrode material porosity and specific surface area to reduce, is unfavorable for the immersion of electrolyte and active material, is unfavorable for the raising of battery performance. The multipolar POSS surface contains a large number of active functional groups. As a hexahedral structure, the polar groups on one side form hydrogen bonds or react with various oxygen-containing functional groups on the surface of the low-temperature carbonized powder, while the polar groups on the other side are exposed, facilitating further hydrogen bonding with the pyrrole monomer and promoting the in-situ polymerization of the pyrrole monomer. The multipolar POSS acts as a bridge between the low-temperature carbonized powder and the pyrrole monomer, facilitating the in-situ polymerization of the pyrrole monomer and forming a low-temperature carbonized powder partially coated with polypyrrole. (The surface of the low-temperature carbonized powder modified with unipolar functional groups is not coated with pyrrole, providing a channel for the subsequent acid etching process, facilitating the corrosion of silica.)

[0014] Overall, the active groups on the exterior of the multipolar functional group POSS significantly enhance the compatibility of the low-temperature carbonized powder with the pyrrole monomer, facilitating the in-situ polymerization of pyrrole. Furthermore, the multipolar functional group POSS can be chemically linked to the polypyrrole polymer chain, forming a continuous macromolecular chain and a network structure across the entire material surface. The monopolar functional group POSS, in addition to enhancing the stability of the low-temperature carbonized powder during high-temperature carbonization, more importantly, provides a pathway for subsequent hydrofluoric acid corrosion, etching away non-conductive materials and increasing porosity and surface area.

[0015] In one embodiment, the low-temperature carbonization in step (1) is carried out under the protection of an inert gas, and the low-temperature carbonization time is 1-2 hours. In particular, the inert gas is nitrogen.

[0016] In one embodiment, the specific process of step (2) is as follows: the low-temperature carbonized powder and the POSS containing a monopolar functional group are dispersed in a solvent, and then reacted at 70-100°C for 4-6 hours, filtered, washed, and dried to obtain a primary modified low-temperature carbonized powder; then the primary modified low-temperature carbonized powder and the POSS containing a multipolar functional group are dispersed in a solvent, reacted at 70-100°C for 4-6 hours, filtered, washed, and dried to obtain a modified low-temperature carbonized powder. The type of solvent is not particularly limited, and N,N-dimethylformamide, N,N-dimethylacetamide, acetone, tetrahydrofuran, toluene, ethylbenzene, methanol, and ethanol commonly used in the art can be used. The reaction can be carried out under reflux conditions. In particular, the temperature of the two-step reaction is 80-90°C. The appropriate reaction temperature can fully exert the capillary adsorption effect of the low-temperature carbonized powder to fully combine the POSS with the low-temperature carbonized powder; it can also avoid the disadvantages of excessively high temperature, excessive molecular movement, and difficulty in adhesion.

[0017] In one embodiment, the monopolar functional group-containing POSS in step (2) is one of monoamino POSS and monoepoxy POSS. In particular, the monoamino POSS is at least one of aminoethyl heptaisobutyl POSS, aminopropyl heptaphenyl POSS, and aminopropyl heptaisobutyl POSS; and the monoepoxy POSS is at least one of heptaisooctyl monoepoxy POSS, heptaisobutyl monoepoxy POSS, and heptaphenyl monoepoxy POSS. In particular, the mass ratio of the low-temperature carbonized powder to the monopolar functional group-containing POSS is any value selected from 1:0.01, 1:0.02, 1:0.03, 1:0.04, 1:0.05, 1:0.06, 1:0.07, 1:0.08, 1:0.09, and 1:0.1.

[0018] In one embodiment, the multipolar functional group-containing POSS in step (2) is one of octaamino POSS and octaepoxy POSS. In particular, the octaamino POSS is at least one of octaaminophenyl POSS and octaaminopropyl POSS; the octaepoxy POSS is at least one of octaglycidyloxypropyl POSS, octaepoxycyclohexyl POSS, and octaepoxycyclohexylethyl POSS. By modifying the low-temperature carbonization powder with a cage-type structure containing a single polar functional group and a multipolar functional group-containing POSS, the stability of the low-temperature carbonization powder can be better improved, and its structural collapse during the high-temperature carbonization process can be prevented. In particular, the mass ratio of the low-temperature carbonization powder to the multipolar functional group-containing POSS is any value selected from 1:0.1, 1:0.15, 1:0.2, 1:0.25, 1:0.3, 1:0.35, and 1:0.4. An appropriate amount of multipolar functional group POSS can not only promote the uniform polymerization of polypyrrole and improve the mechanical stability of low-temperature carbonized powder, but also avoid the problem of excessive pores after acid corrosion caused by excessive POSS, resulting in unstable structure and easy collapse.

[0019] In one embodiment, the mass ratio of the low-temperature carbonized powder to the pyrrole monomer in step (3) is 1:(0.1-0.4); 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). The modified low-temperature carbonized powder has a more stable structure and a larger specific surface area, allowing for the attachment of more pyrrole monomers, thereby improving the nitrogen doping effect.

[0020] In one embodiment, the reaction temperature in step (3) is 0-5°C, and the reaction time is 8-12 hours.

[0021] In one embodiment, the high-temperature carbonization in step (4) is performed under the protection of an inert gas for 3-4 hours. Specifically, the inert gas can be any one of helium, nitrogen, and argon.

[0022] In one embodiment, the mass concentration of the hydrofluoric acid solution in step (4) is 5-12 wt%.

[0023] In another aspect, the present invention also provides a polypyrrole-modified carbon electrode material for bio-based fuel cells prepared by the above-mentioned preparation method. This electrode material has a large specific surface area, high electrical conductivity, and broad application prospects.

[0024] Beneficial effect: Nitrogen-doped biomass carbon material has the advantages of environmental protection and low cost, but due to defects such as low mechanical strength and poor electrical conductivity, its further application is limited. The present invention solves the above problems by nitrogen-doping modification of POSS and polypyrrole containing different numbers of polar functional groups. One end of the POSS containing unipolar functional groups is connected to the low-temperature carbonized powder, and the other end is hydrophobic, which prevents the loading of pyrrole monomer and is conducive to the corrosion of oxides such as silicon dioxide by hydrofluoric acid. The surface of the POSS with multipolar functional groups contains more active functional groups. The polar groups on one side form hydrogen bonds or react with various oxygen-containing functional groups on the surface of the low-temperature carbonized powder, while the polar functional groups on the other side are exposed to the outside, which is convenient for further forming hydrogen bonds with the pyrrole monomer and promoting the in-situ polymerization of the pyrrole monomer. In addition, the POSS with multipolar functional groups can be connected to the polypyrrole polymer chain through chemical bonds. A continuous macromolecular chain is formed, and a network structure is formed on the entire material surface. The role of the unipolar functional group POSS is not only to improve the stability of the low-temperature carbonized powder during the high-temperature carbonization process, but its more important role is to provide a channel for subsequent hydrofluoric acid corrosion, etching away non-conductive substances and increasing porosity and surface area. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] 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.

[0026] Figure 1 This is a scanning electron microscope image of the polypyrrole-modified low-temperature carbonized powder prepared in Example 10 of the present invention.

[0027] Figure 2 This is a scanning electron microscope image of the polypyrrole-modified low-temperature carbonized powder prepared in Comparative Example 1 of the present invention.

[0028] Figure 3 This is a scanning electron microscope image of the polypyrrole-modified carbon electrode material for bio-based fuel cells prepared in Example 10 of the present invention.

[0029] Figure 4 This is a scanning electron microscope image of the polypyrrole-modified carbon electrode material for bio-based fuel cells prepared in Comparative Example 1 of the present invention. DETAILED DESCRIPTION

[0030] The embodiments of the present invention will be described in detail below with reference to the examples, but it will be understood by those skilled in the art that the following examples are merely illustrative of the present invention and should not be construed as limiting the scope of the invention. Where specific conditions are not specified in the examples, the methods were performed according to conventional conditions or the conditions recommended by the manufacturer. Where the manufacturers of the reagents or instruments are not specified, they are all conventional products that can be obtained commercially.

[0031] Example 1

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

[0033] (1) Under nitrogen protection, the cleaned rice husk was carbonized at low temperature and ground into low temperature carbonized powder; the low temperature carbonization temperature was 400℃ and the time was 2h;

[0034] (2) The low-temperature carbonized powder and the POSS containing a unipolar functional group are dispersed in a solvent N,N-dimethylformamide, and then reacted at 80°C for 6 hours. After filtering, washing, and drying, a primary modified low-temperature carbonized powder is obtained. The primary modified low-temperature carbonized powder and the POSS containing a multipolar functional group are then dispersed in a solvent toluene, reacted at 80°C for 6 hours, and filtered, washed, and dried to obtain a modified low-temperature carbonized powder. The mass ratio of the low-temperature carbonized powder to the POSS containing a unipolar functional group is 1:0.01. The mass ratio of the low-temperature carbonized powder to the POSS containing a multipolar functional group is 1:0.1. The POSS containing a unipolar functional group is aminopropyl heptaisobutyl POSS. The POSS containing a multipolar functional group is octaglycidyloxypropyl POSS.

[0035] (3) The modified low-temperature carbonized powder is uniformly dispersed in deionized water, and then pyrrole monomer is added dropwise to obtain a mixed solution; an aqueous solution containing ammonium persulfate oxidant is added dropwise to the mixed solution under stirring, and the mixture is reacted at 0°C for 8 hours to obtain polypyrrole modified low-temperature carbonized powder; the mass ratio of the low-temperature carbonized powder to the pyrrole monomer is 1:0.1; the mass ratio of the pyrrole monomer to the oxidant is 1:2.8;

[0036] (4) The polypyrrole-modified low-temperature carbonized powder was subjected to high-temperature carbonization under nitrogen protection, and then corroded with 8wt% hydrofluoric acid solution, cleaned, and dried to obtain a polypyrrole-modified carbon electrode material for bio-based fuel cells; the high-temperature carbonization temperature was 900℃ and the time was 4h. The specific surface area and conductivity of the polypyrrole-modified carbon electrode material for bio-based fuel cells were tested using the BET method and a conductivity tester. The specific surface area was 1639m 2 g -1 , the conductivity is 19.2Scm -1 .

[0037] Example 2

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

[0039] (1) Under nitrogen protection, the cleaned rice husk was carbonized at low temperature and ground into low temperature carbonized powder; the low temperature carbonization temperature was 550℃ and the time was 1h;

[0040] (2) The low-temperature carbonized powder and the POSS containing a unipolar functional group are dispersed in a solvent N,N-dimethylformamide, and then reacted at 90°C for 4 hours. After filtering, washing, and drying, a primary modified low-temperature carbonized powder is obtained. The primary modified low-temperature carbonized powder and the POSS containing a multipolar functional group are then dispersed in a solvent toluene, reacted at 90°C for 4 hours, and filtered, washed, and dried to obtain a modified low-temperature carbonized powder. The mass ratio of the low-temperature carbonized powder to the POSS containing a unipolar functional group is 1:0.1. The mass ratio of the low-temperature carbonized powder to the POSS containing a multipolar functional group is 1:0.3. The POSS containing a unipolar functional group is aminopropyl heptaisobutyl POSS. The POSS containing a multipolar functional group is octaglycidyloxypropyl POSS.

[0041] (3) The modified low-temperature carbonized powder is uniformly dispersed in deionized water, and then pyrrole monomer is added dropwise to obtain a mixed solution; an aqueous solution containing ammonium persulfate oxidant is added dropwise to the mixed solution under stirring, and the mixture is reacted at 0°C for 12 hours to obtain polypyrrole modified low-temperature carbonized powder; the mass ratio of the low-temperature carbonized powder to the pyrrole monomer is 1:0.4; the mass ratio of the pyrrole monomer to the oxidant is 1:3.3;

[0042] (4) The polypyrrole-modified low-temperature carbonized powder was subjected to high-temperature carbonization under nitrogen protection, and then corroded with 8wt% hydrofluoric acid solution, cleaned, and dried to obtain a polypyrrole-modified carbon electrode material for bio-based fuel cells; the high-temperature carbonization temperature was 1200°C and the time was 3h. The specific surface area and conductivity of the polypyrrole-modified carbon electrode material for bio-based fuel cells were tested using the BET method and a conductivity tester. The specific surface area was 1851m 2 g -1 , the conductivity is 26.3Scm -1 .

[0043] Example 3

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

[0045] (1) Under nitrogen protection, the cleaned rice husk was carbonized at low temperature and ground into low temperature carbonized powder; the low temperature carbonization temperature was 480℃ and the time was 1.5h;

[0046] (2) The low-temperature carbonized powder and the POSS containing a unipolar functional group are dispersed in a solvent N,N-dimethylformamide, and then reacted at 70°C for 5 hours. After filtering, washing, and drying, a primary modified low-temperature carbonized powder is obtained. The primary modified low-temperature carbonized powder and the POSS containing a multipolar functional group are then dispersed in a solvent toluene, reacted at 70°C for 5 hours, and filtered, washed, and dried to obtain a modified low-temperature carbonized powder. The mass ratio of the low-temperature carbonized powder to the POSS containing a unipolar functional group is 1:0.05. The mass ratio of the low-temperature carbonized powder to the POSS containing a multipolar functional group is 1:0.2. The POSS containing a unipolar functional group is aminopropyl heptaisobutyl POSS. The POSS containing a multipolar functional group is octaglycidyloxypropyl POSS.

[0047] (3) The modified low-temperature carbonized powder is uniformly dispersed in deionized water, and then pyrrole monomer is added dropwise to obtain a mixed solution; an aqueous solution containing ammonium persulfate oxidant is added dropwise to the mixed solution under stirring, and the mixture is reacted at 0°C for 11 hours to obtain polypyrrole modified low-temperature carbonized powder; the mass ratio of the low-temperature carbonized powder to the pyrrole monomer is 1:0.3; the mass ratio of the pyrrole monomer to the oxidant is 1:3;

[0048] (4) The polypyrrole-modified low-temperature carbonized powder was subjected to high-temperature carbonization under nitrogen protection, and then corroded with 8wt% hydrofluoric acid solution, cleaned, and dried to obtain a polypyrrole-modified carbon electrode material for bio-based fuel cells; the high-temperature carbonization temperature was 1100°C and the time was 3.5h. The specific surface area and conductivity of the polypyrrole-modified carbon electrode material for bio-based fuel cells were tested using the BET method and a conductivity tester. The specific surface area was 1667m 2 g -1 , the conductivity is 22.3Scm -1 .

[0049] Example 4

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

[0051] (1) Under nitrogen protection, the cleaned rice husk was carbonized at low temperature and ground into low temperature carbonized powder; the low temperature carbonization temperature was 550℃ and the time was 2h;

[0052] (2) The low-temperature carbonized powder and the POSS containing a unipolar functional group are dispersed in a solvent N,N-dimethylformamide, and then reacted at 80°C for 4 hours. After filtering, washing, and drying, a primary modified low-temperature carbonized powder is obtained. The primary modified low-temperature carbonized powder and the POSS containing a multipolar functional group are then dispersed in a solvent toluene, reacted at 90°C for 6 hours, and filtered, washed, and dried to obtain a modified low-temperature carbonized powder. The mass ratio of the low-temperature carbonized powder to the POSS containing a unipolar functional group is 1:0.01. The mass ratio of the low-temperature carbonized powder to the POSS containing a multipolar functional group is 1:0.3. The POSS containing a unipolar functional group is aminopropyl heptaisobutyl POSS. The POSS containing a multipolar functional group is octaglycidyloxypropyl POSS.

[0053] (3) The modified low-temperature carbonized powder is uniformly dispersed in deionized water, and then pyrrole monomer is added dropwise to obtain a mixed solution; an aqueous solution containing ammonium persulfate oxidant is added dropwise to the mixed solution under stirring, and the mixture is reacted at 0°C for 8 hours to obtain polypyrrole modified low-temperature carbonized powder; the mass ratio of the low-temperature carbonized powder to the pyrrole monomer is 1:0.15; the mass ratio of the pyrrole monomer to the oxidant is 1:3.3;

[0054] (4) The polypyrrole-modified low-temperature carbonized powder was subjected to high-temperature carbonization under nitrogen protection, and then corroded with 8wt% hydrofluoric acid solution, cleaned, and dried to obtain a polypyrrole-modified carbon electrode material for bio-based fuel cells; the high-temperature carbonization temperature was 900℃ and the time was 3h. The specific surface area and conductivity of the polypyrrole-modified carbon electrode material for bio-based fuel cells were tested using the BET method and a conductivity tester. The specific surface area was 1716m 2 g -1 , the conductivity is 21.6Scm -1 .

[0055] Example 5

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

[0057] (1) Under nitrogen protection, the cleaned rice husk was carbonized at low temperature and ground into low temperature carbonized powder; the low temperature carbonization temperature was 480℃ and the time was 1.5h;

[0058] (2) The low-temperature carbonized powder and the POSS containing a unipolar functional group are dispersed in a solvent N,N-dimethylformamide, and then reacted at 100°C for 5 hours. After filtering, washing, and drying, a primary modified low-temperature carbonized powder is obtained. The primary modified low-temperature carbonized powder and the POSS containing a multipolar functional group are then dispersed in a solvent toluene, reacted at 100°C for 5 hours, and filtered, washed, and dried to obtain a modified low-temperature carbonized powder. The mass ratio of the low-temperature carbonized powder to the POSS containing a unipolar functional group is 1:0.05. The mass ratio of the low-temperature carbonized powder to the POSS containing a multipolar functional group is 1:0.2. The POSS containing a unipolar functional group is aminopropyl heptaisobutyl POSS. The POSS containing a multipolar functional group is octaglycidyloxypropyl POSS.

[0059] (3) The modified low-temperature carbonized powder is uniformly dispersed in deionized water, and then pyrrole monomer is added dropwise to obtain a mixed solution; an aqueous solution containing ammonium persulfate oxidant is added dropwise to the mixed solution under stirring, and the mixture is reacted at 0°C for 11 hours to obtain polypyrrole modified low-temperature carbonized powder; the mass ratio of the low-temperature carbonized powder to the pyrrole monomer is 1:0.3; the mass ratio of the pyrrole monomer to the oxidant is 1:3;

[0060] (4) The polypyrrole-modified low-temperature carbonized powder was subjected to high-temperature carbonization under nitrogen protection, and then corroded with 8wt% hydrofluoric acid solution, cleaned, and dried to obtain a polypyrrole-modified carbon electrode material for bio-based fuel cells; the high-temperature carbonization temperature was 1100°C and the time was 3.5h. The specific surface area and conductivity of the polypyrrole-modified carbon electrode material for bio-based fuel cells were tested using the BET method and a conductivity tester. The specific surface area was 1675m 2 g -1 , conductivity is 20.8Scm -1 .

[0061] Example 6

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

[0063] (1) Under nitrogen protection, the cleaned rice husk was carbonized at low temperature and ground to obtain low temperature carbonized powder; the low temperature carbonization temperature was 430℃ and the time was 1.8h;

[0064] (2) The low-temperature carbonized powder and the POSS containing a unipolar functional group are dispersed in a solvent N,N-dimethylformamide, and then reacted at 83°C for 5.5 hours. After filtering, washing, and drying, a primary modified low-temperature carbonized powder is obtained. The primary modified low-temperature carbonized powder and the POSS containing a multipolar functional group are then dispersed in a solvent toluene, reacted at 82°C for 5.4 hours, and filtered, washed, and dried to obtain a modified low-temperature carbonized powder. The mass ratio of the low-temperature carbonized powder to the POSS containing a unipolar functional group is 1:0.03. The mass ratio of the low-temperature carbonized powder to the POSS containing a multipolar functional group is 1:0.15. The POSS containing a unipolar functional group is aminopropyl heptaisobutyl POSS. The POSS containing a multipolar functional group is octaglycidyloxypropyl POSS.

[0065] (3) The modified low-temperature carbonized powder is uniformly dispersed in deionized water, and then pyrrole monomer is added dropwise to obtain a mixed solution; an aqueous solution containing ammonium persulfate oxidant is added dropwise to the mixed solution under stirring, and the mixture is reacted at 0°C for 9 hours to obtain polypyrrole modified low-temperature carbonized powder; the mass ratio of the low-temperature carbonized powder to the pyrrole monomer is 1:0.2; the mass ratio of the pyrrole monomer to the oxidant is 1:2.9;

[0066] (4) The polypyrrole-modified low-temperature carbonized powder was subjected to high-temperature carbonization under nitrogen protection, and then corroded with 8wt% hydrofluoric acid solution, cleaned, and dried to obtain a polypyrrole-modified carbon electrode material for bio-based fuel cells; the high-temperature carbonization temperature was 1000℃ and the time was 3.7h. The specific surface area and conductivity of the polypyrrole-modified carbon electrode material for bio-based fuel cells were tested using the BET method and a conductivity tester. The specific surface area was 1704m 2 g -1 , the conductivity is 22.7Scm -1 .

[0067] Example 7

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

[0069] (1) Under nitrogen protection, the cleaned rice husk was carbonized at low temperature and ground into low temperature carbonized powder; the low temperature carbonization temperature was 480℃ and the time was 1.5h;

[0070] (2) The low-temperature carbonized powder and the POSS containing a unipolar functional group are dispersed in a solvent N,N-dimethylformamide, and then reacted at 85°C for 5 hours. After filtering, washing, and drying, a primary modified low-temperature carbonized powder is obtained. The primary modified low-temperature carbonized powder and the POSS containing a multipolar functional group are then dispersed in a solvent toluene, reacted at 85°C for 5 hours, and filtered, washed, and dried to obtain a modified low-temperature carbonized powder. The mass ratio of the low-temperature carbonized powder to the POSS containing a unipolar functional group is 1:0.05. The mass ratio of the low-temperature carbonized powder to the POSS containing a multipolar functional group is 1:0.4. The POSS containing a unipolar functional group is aminopropyl heptaisobutyl POSS. The POSS containing a multipolar functional group is octaglycidyloxypropyl POSS.

[0071] (3) The modified low-temperature carbonized powder is uniformly dispersed in deionized water, and then pyrrole monomer is added dropwise to obtain a mixed solution; an aqueous solution containing ammonium persulfate oxidant is added dropwise to the mixed solution under stirring, and the mixture is reacted at 0°C for 11 hours to obtain polypyrrole modified low-temperature carbonized powder; the mass ratio of the low-temperature carbonized powder to the pyrrole monomer is 1:0.3; the mass ratio of the pyrrole monomer to the oxidant is 1:3;

[0072] (4) The polypyrrole-modified low-temperature carbonized powder was subjected to high-temperature carbonization under nitrogen protection, and then corroded with 8wt% hydrofluoric acid solution, cleaned, and dried to obtain a polypyrrole-modified carbon electrode material for bio-based fuel cells; the high-temperature carbonization temperature was 1100°C and the time was 3.5h. The specific surface area and conductivity of the polypyrrole-modified carbon electrode material for bio-based fuel cells were tested using the BET method and a conductivity tester. The specific surface area was 1758m 2 g -1 , the conductivity is 21.2Scm -1 .

[0073] Example 8

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

[0075] (1) Under nitrogen protection, the cleaned rice husk was carbonized at low temperature and ground to obtain low temperature carbonized powder; the low temperature carbonization temperature was 520℃ and the time was 1.2h;

[0076] (2) The low-temperature carbonized powder and the POSS containing a unipolar functional group are dispersed in a solvent N,N-dimethylformamide, and then reacted at 88°C for 4.5 hours. After filtering, washing, and drying, a primary modified low-temperature carbonized powder is obtained. The primary modified low-temperature carbonized powder and the POSS containing a multipolar functional group are then dispersed in a solvent toluene, reacted at 87°C for 4.6 hours, and filtered, washed, and dried to obtain a modified low-temperature carbonized powder. The mass ratio of the low-temperature carbonized powder to the POSS containing a unipolar functional group is 1:0.08. The mass ratio of the low-temperature carbonized powder to the POSS containing a multipolar functional group is 1:0.25. The POSS containing a unipolar functional group is aminopropyl heptaisobutyl POSS. The POSS containing a multipolar functional group is octaglycidyloxypropyl POSS.

[0077] (3) The modified low-temperature carbonized powder is uniformly dispersed in deionized water, and then pyrrole monomer is added dropwise to obtain a mixed solution; an aqueous solution containing ammonium persulfate oxidant is added dropwise to the mixed solution under stirring, and the mixture is reacted at 0°C for 11 hours to obtain polypyrrole modified low-temperature carbonized powder; the mass ratio of the low-temperature carbonized powder to the pyrrole monomer is 1:0.35; the mass ratio of the pyrrole monomer to the oxidant is 1:3.2;

[0078] (4) The polypyrrole-modified low-temperature carbonized powder was subjected to high-temperature carbonization under nitrogen protection, and then corroded with 8wt% hydrofluoric acid solution, cleaned, and dried to obtain a polypyrrole-modified carbon electrode material for bio-based fuel cells; the high-temperature carbonization temperature was 1050°C and the time was 3.8h. The specific surface area and conductivity of the polypyrrole-modified carbon electrode material for bio-based fuel cells were tested using the BET method and a conductivity tester. The specific surface area was 1783m 2 g -1 , the conductivity is 25.4Scm -1 .

[0079] Example 9

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

[0081] (1) Under nitrogen protection, the cleaned rice husk was carbonized at low temperature and ground into low temperature carbonized powder; the low temperature carbonization temperature was 500℃ and the time was 1.2h;

[0082] (2) The low-temperature carbonized powder and the POSS containing a unipolar functional group are dispersed in a solvent N,N-dimethylformamide, and then reacted at 82°C for 4.6 hours. After filtering, washing, and drying, a primary modified low-temperature carbonized powder is obtained. The primary modified low-temperature carbonized powder and the POSS containing a multipolar functional group are then dispersed in a solvent toluene, reacted at 88°C for 4.6 hours, and filtered, washed, and dried to obtain a modified low-temperature carbonized powder. The mass ratio of the low-temperature carbonized powder to the POSS containing a unipolar functional group is 1:0.06. The mass ratio of the low-temperature carbonized powder to the POSS containing a multipolar functional group is 1:0.23. The POSS containing a unipolar functional group is aminopropyl heptaisobutyl POSS. The POSS containing a multipolar functional group is octaglycidyloxypropyl POSS.

[0083] (3) The modified low-temperature carbonized powder is uniformly dispersed in deionized water, and then pyrrole monomer is added dropwise to obtain a mixed solution; an aqueous solution containing ammonium persulfate oxidant is added dropwise to the mixed solution under stirring, and the mixture is reacted at 0°C for 9 hours to obtain polypyrrole modified low-temperature carbonized powder; the mass ratio of the low-temperature carbonized powder to the pyrrole monomer is 1:0.27; the mass ratio of the pyrrole monomer to the oxidant is 1:3;

[0084] (4) The polypyrrole-modified low-temperature carbonized powder was subjected to high-temperature carbonization under nitrogen protection, and then corroded with 8wt% hydrofluoric acid solution, cleaned, and dried to obtain a polypyrrole-modified carbon electrode material for bio-based fuel cells; the high-temperature carbonization temperature was 1140°C and the time was 3.8h. The specific surface area and conductivity of the polypyrrole-modified carbon electrode material for bio-based fuel cells were tested using the BET method and a conductivity tester. The specific surface area was 1811m 2 g -1 , the conductivity is 24.1Scm -1 .

[0085] Example 10

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

[0087] (1) Under nitrogen protection, the cleaned rice husk was carbonized at low temperature and ground into low temperature carbonized powder; the low temperature carbonization temperature was 480℃ and the time was 1.5h;

[0088] (2) The low-temperature carbonized powder and the POSS containing a unipolar functional group are dispersed in a solvent N,N-dimethylformamide, and then reacted at 85°C for 5 hours. After filtering, washing, and drying, a primary modified low-temperature carbonized powder is obtained. The primary modified low-temperature carbonized powder and the POSS containing a multipolar functional group are then dispersed in a solvent toluene, reacted at 85°C for 5 hours, and filtered, washed, and dried to obtain a modified low-temperature carbonized powder. The mass ratio of the low-temperature carbonized powder to the POSS containing a unipolar functional group is 1:0.05. The mass ratio of the low-temperature carbonized powder to the POSS containing a multipolar functional group is 1:0.2. The POSS containing a unipolar functional group is aminopropyl heptaisobutyl POSS. The POSS containing a multipolar functional group is octaglycidyloxypropyl POSS.

[0089] (3) The modified low-temperature carbonized powder is uniformly dispersed in deionized water, and then pyrrole monomer is added dropwise to obtain a mixed solution; an aqueous solution containing ammonium persulfate oxidant is added dropwise to the mixed solution under stirring, and the mixture is reacted at 0°C for 11 hours to obtain polypyrrole modified low-temperature carbonized powder; the mass ratio of the low-temperature carbonized powder to the pyrrole monomer is 1:0.3; the mass ratio of the pyrrole monomer to the oxidant is 1:3;

[0090] (4) The polypyrrole-modified low-temperature carbonized powder was subjected to high-temperature carbonization under nitrogen protection, and then corroded with 8wt% hydrofluoric acid solution, cleaned, and dried to obtain a polypyrrole-modified carbon electrode material for bio-based fuel cells; the high-temperature carbonization temperature was 1100°C and the time was 3.5h. The specific surface area and conductivity of the polypyrrole-modified carbon electrode material for bio-based fuel cells were tested using the BET method and a conductivity tester. The specific surface area was 1842m 2 g -1 , conductivity is 26.5Scm -1 .

[0091] Comparative Example 1

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

[0093] (1) Under nitrogen protection, the cleaned rice husk was carbonized at low temperature and ground into low temperature carbonized powder; the low temperature carbonization temperature was 480℃ and the time was 1.5h;

[0094] (2) The low-temperature carbonized powder and the POSS containing multipolar functional groups are dispersed in a solvent of toluene, reacted at 85°C for 5 hours, filtered, washed, and dried to obtain a primary modified low-temperature carbonized powder; the primary modified low-temperature carbonized powder and the POSS containing unipolar functional groups are then dispersed in a solvent of N,N-dimethylformamide, reacted at 85°C for 5 hours, filtered, washed, and dried to obtain a modified low-temperature carbonized powder; the mass ratio of the low-temperature carbonized powder to the POSS containing unipolar functional groups is 1:0.05; the mass ratio of the low-temperature carbonized powder to the POSS containing multipolar functional groups is 1:0.2; the POSS containing unipolar functional groups is aminopropyl heptaisobutyl POSS; the POSS containing multipolar functional groups is octaglycidyloxypropyl POSS;

[0095] (3) The modified low-temperature carbonized powder is uniformly dispersed in deionized water, and then pyrrole monomer is added dropwise to obtain a mixed solution; an aqueous solution containing ammonium persulfate oxidant is added dropwise to the mixed solution under stirring, and the mixture is reacted at 0°C for 11 hours to obtain polypyrrole modified low-temperature carbonized powder; the mass ratio of the low-temperature carbonized powder to the pyrrole monomer is 1:0.3; the mass ratio of the pyrrole monomer to the oxidant is 1:3;

[0096] (4) The polypyrrole-modified low-temperature carbonized powder was subjected to high-temperature carbonization under nitrogen protection, and then corroded with 8wt% hydrofluoric acid solution, cleaned, and dried to obtain a polypyrrole-modified carbon electrode material for bio-based fuel cells; the high-temperature carbonization temperature was 1100°C and the time was 3.5h. The specific surface area and conductivity of the polypyrrole-modified carbon electrode material for bio-based fuel cells were tested using the BET method and a conductivity tester. The specific surface area was 954m 2 g -1 , the conductivity is 7.1Scm -1 .

[0097] Comparative Example 2

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

[0099] (1) Under nitrogen protection, the cleaned rice husk was carbonized at low temperature and ground into low temperature carbonized powder; the low temperature carbonization temperature was 480℃ and the time was 1.5h;

[0100] (2) The low-temperature carbonized powder and the POSS containing a unipolar functional group are dispersed in a solvent N,N-dimethylformamide, and then reacted at 85°C for 5 hours. After filtering, washing, and drying, a primary modified low-temperature carbonized powder is obtained. The primary modified low-temperature carbonized powder and the POSS containing a multipolar functional group are then dispersed in a solvent toluene, reacted at 85°C for 5 hours, and filtered, washed, and dried to obtain a modified low-temperature carbonized powder. The mass ratio of the low-temperature carbonized powder to the POSS containing a unipolar functional group is 1:0.2. The mass ratio of the low-temperature carbonized powder to the POSS containing a multipolar functional group is 1:0.05. The POSS containing a unipolar functional group is aminopropyl heptaisobutyl POSS. The POSS containing a multipolar functional group is octaglycidyloxypropyl POSS.

[0101] (3) The modified low-temperature carbonized powder is uniformly dispersed in deionized water, and then pyrrole monomer is added dropwise to obtain a mixed solution; an aqueous solution containing ammonium persulfate oxidant is added dropwise to the mixed solution under stirring, and the mixture is reacted at 0°C for 11 hours to obtain polypyrrole modified low-temperature carbonized powder; the mass ratio of the low-temperature carbonized powder to the pyrrole monomer is 1:0.3; the mass ratio of the pyrrole monomer to the oxidant is 1:3;

[0102] (4) The polypyrrole-modified low-temperature carbonized powder was subjected to high-temperature carbonization under nitrogen protection, and then corroded with 8wt% hydrofluoric acid solution, cleaned, and dried to obtain a polypyrrole-modified carbon electrode material for bio-based fuel cells; the high-temperature carbonization temperature was 1100°C and the time was 3.5h. The specific surface area and conductivity of the polypyrrole-modified carbon electrode material for bio-based fuel cells were tested using the BET method and a conductivity tester. The specific surface area was 1366m 2 g -1 , the conductivity is 3.9Scm -1 .

[0103] Comparative Example 3

[0104] A method for preparing a polypyrrole-modified carbon electrode material for a bio-based fuel cell comprises the following steps:

[0105] (1) Under nitrogen protection, the cleaned rice husk was carbonized at low temperature and ground into low temperature carbonized powder; the low temperature carbonization temperature was 650℃ and the time was 1.5h;

[0106] (2) The low-temperature carbonized powder and the POSS containing a unipolar functional group are dispersed in a solvent N,N-dimethylformamide, and then reacted at 85°C for 5 hours. After filtering, washing, and drying, a primary modified low-temperature carbonized powder is obtained. The primary modified low-temperature carbonized powder and the POSS containing a multipolar functional group are then dispersed in a solvent toluene, reacted at 85°C for 5 hours, and filtered, washed, and dried to obtain a modified low-temperature carbonized powder. The mass ratio of the low-temperature carbonized powder to the POSS containing a unipolar functional group is 1:0.05. The mass ratio of the low-temperature carbonized powder to the POSS containing a multipolar functional group is 1:0.2. The POSS containing a unipolar functional group is aminopropyl heptaisobutyl POSS. The POSS containing a multipolar functional group is octaglycidyloxypropyl POSS.

[0107] (3) The modified low-temperature carbonized powder is uniformly dispersed in deionized water, and then pyrrole monomer is added dropwise to obtain a mixed solution; an aqueous solution containing ammonium persulfate oxidant is added dropwise to the mixed solution under stirring, and the mixture is reacted at 0°C for 11 hours to obtain polypyrrole modified low-temperature carbonized powder; the mass ratio of the low-temperature carbonized powder to the pyrrole monomer is 1:0.3; the mass ratio of the pyrrole monomer to the oxidant is 1:3;

[0108] (4) The polypyrrole-modified low-temperature carbonized powder was subjected to high-temperature carbonization under nitrogen protection, and then corroded with 8wt% hydrofluoric acid solution, cleaned, and dried to obtain a polypyrrole-modified carbon electrode material for bio-based fuel cells; the high-temperature carbonization temperature was 1100°C and the time was 3.5h. The specific surface area and conductivity of the polypyrrole-modified carbon electrode material for bio-based fuel cells were tested using the BET method and a conductivity tester. The specific surface area was 1238m 2 g -1 , conductivity is 8.8Scm -1 .

[0109] As can be seen from the foregoing embodiment and comparative examples, the present invention solves the problem of system structure collapse and shrinkage when low temperature carbonization powder modification solves polypyrrole uneven load and high temperature carbonization by the POSS containing different number polar functional groups.Wherein, one end containing unipolar functional group POSS is connected with low temperature carbonization powder, and the other end presents hydrophobicity, prevents the load of pyrrole monomer, is conducive to the corrosion of hydrofluoric acid to oxide compounds such as silicon dioxide.And the multipolar functional group POSS surface contains more active functional groups, the polar group on its side and the various oxygen-containing functional groups on the low temperature carbonization powder surface form hydrogen bond or react, and the opposite side polar functional group is then exposed to the outside, and it is convenient to further form hydrogen bond with pyrrole monomer, promotes the in-situ polymerization of pyrrole monomer.In addition, the multipolar functional group POSS can be connected with the polypyrrole polymer chain by chemical bond.Form a continuous macromolecular chain, and form network structure on whole material surface. The role of the unipolar functional group POSS is not only to improve the stability of the low-temperature carbonized powder during the high-temperature carbonization process, but its more important role is to provide a channel for subsequent hydrofluoric acid corrosion, etching away non-conductive substances and increasing the specific surface area.

[0110] Specifically, compared with Example 10, Comparative Example 1 first adopts multipolar functional group POSS modification low temperature carbonization powder, it is more containing the polar functional group on the multipolar functional group POSS, very easily form hydrogen bond or react with the oxygen-containing functional group on the low temperature carbonization powder, due to the difference in reactivity ratio and the huge steric hindrance effect of POSS, the multipolar functional group POSS of preferential attachment can affect the bonding action of unipolar functional group POSS and low temperature carbonization powder subsequently, is unfavorable for its attachment and uniform dispersion.And the disappearance of unipolar functional group POSS, makes pyrrole monomer form coating structure at low temperature carbonization powder and multipolar functional group POSS surface polymerization, after high temperature carbonization, carbonized polypyrrole forms dense carbon structure on outer surface, is unfavorable for the corrosion of hydrofluoric acid, cannot effectively remove silicon-containing oxides such as silicon dioxide, cause carbon electrode material electrical conductivity and porosity to reduce, specific surface area reduces. In conjunction with accompanying drawing, it can also be seen that the corresponding Figure 2 A dense polypyrrole coating is formed on the surface of the powder during carbonization at medium and low temperatures. Figure 1 The polypyrrole on the surface of the low-temperature carbonized powder does not form a dense covering structure, but presents a relatively loose morphology. This loose structure is conducive to the etching of oxides such as silicon dioxide by hydrofluoric acid, thereby improving the electrical conductivity and porosity. Figure 3 and Figure 4 It can also be seen that the carbon electrode material prepared in Example 10 has an interconnected porous structure with rich pore structure, which not only increases the specific surface area, but also contributes to the formation of conductive paths and improves the electrical conductivity; while the carbon electrode material prepared in Comparative Example 1 has a block structure formed by collapse and merging, lacks effective connection with each other, has a reduced specific surface area, and reduces the electrical conductivity.

[0111] And comparative example 2 is compared with embodiment 10, and unipolar functional group POSS and multipolar functional group POSS consumption exchange, cause low temperature carbonization powder to be covered by too much unipolar functional group POSS, the strong hydrophobicity of unipolar functional group POSS causes pyrrole monomer to cannot in-situ polymerization, and doping efficiency reduces, and specific conductivity declines.Comparative example 3 shows the temperature that should control low temperature carbonization, rice husk is carried out to low temperature carbonization, is in order to remove its surface inert matter, makes rice husk generation preliminary carbonization by low temperature carbonization process simultaneously, makes it form the elementary carbonized material containing various oxygen-containing functional groups, facilitates the modification containing polar functional group POSS subsequently.Comparative example 3 low temperature carbonization temperature is too high, and part rice husk has begun to complete carbonization process, causes surface oxygen-containing functional group quantity to reduce, is unfavorable for the attachment modification containing polar functional group POSS, lacks the reinforcement containing silicon oxide, easily causes structural collapse when high temperature carbonization, affects the formation of conductive path and the increase of specific surface area.

[0112] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any other manner. Any person skilled in the art may utilize the above-disclosed technical content to modify or modify the present invention into equivalent embodiments. However, any simple modifications, equivalent variations, and modifications to the above embodiments that do not depart from the technical content of the present invention and are based on the technical essence of the present invention remain within the scope of protection of the present invention.

Claims

1. A method for preparing a polypyrrole-modified carbon electrode material for a bio-based fuel cell, characterized in that: The following steps are involved: (1) Carbonizing rice husks at low temperature and grinding them to obtain low temperature carbonized powder; the low temperature carbonization temperature is 400-550°C; (2) firstly modifying the low-temperature carbonization powder with a unipolar functional group-containing POSS to obtain a primary modified low-temperature carbonization powder; then modifying the primary modified low-temperature carbonization powder again with a multipolar functional group-containing POSS to obtain a modified low-temperature carbonization powder; the number of polar functional groups on the multipolar functional group-containing POSS is greater than 4; the mass ratio of the low-temperature carbonization powder to the unipolar functional group-containing POSS is 1:(0.01-0.1); the mass ratio of the low-temperature carbonization powder to the multipolar functional group-containing POSS is 1:(0.1-0.4); (3) dispersing the modified low-temperature carbonized powder in deionized water, and then adding pyrrole monomer and an aqueous solution containing an oxidant dropwise to obtain polypyrrole modified low-temperature carbonized powder after reaction; (4) The polypyrrole-modified low-temperature carbonization powder is carbonized at a high temperature, and then corroded with a hydrofluoric acid solution, cleaned, and dried to obtain a polypyrrole-modified carbon electrode material for a bio-based fuel cell; the high-temperature carbonization temperature is 900-1200°C.

2. The method for preparing a polypyrrole-modified carbon electrode material for a bio-based fuel cell according to claim 1, wherein: In step (1), the low-temperature carbonization is carried out under the protection of an inert gas; the time for the low-temperature carbonization is 1-2 hours.

3. The method for preparing a polypyrrole-modified carbon electrode material for a bio-based fuel cell according to claim 1, wherein: The specific process of step (2) is as follows: dispersing the low-temperature carbonized powder and the POSS containing a unipolar functional group in a solvent, then reacting at 70-100° C. for 4-6 hours, filtering, washing, and drying to obtain the primary modified low-temperature carbonized powder; then dispersing the primary modified low-temperature carbonized powder and the POSS containing a multipolar functional group in a solvent, reacting at 70-100° C. for 4-6 hours, filtering, washing, and drying to obtain the modified low-temperature carbonized powder.

4. The method for preparing a polypyrrole-modified carbon electrode material for a bio-based fuel cell according to claim 1, wherein: The POSS containing a monopolar functional group in step (2) is one of monoamino POSS and monoepoxy POSS.

5. The method for preparing a polypyrrole-modified carbon electrode material for a bio-based fuel cell according to claim 1, wherein: The multipolar functional group-containing POSS in step (2) is one of octaamino POSS and octaepoxy POSS.

6. The method for preparing a polypyrrole-modified carbon electrode material for a bio-based fuel cell according to claim 1, wherein: In step (3), the mass ratio of the low-temperature carbonized powder to the pyrrole monomer is 1:(0.1-0.4); 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 carbon electrode material for a bio-based fuel cell according to claim 1, wherein: The reaction temperature in step (3) is 0-5°C and the reaction time is 8-12h.

8. The method for preparing a polypyrrole-modified carbon electrode material for a bio-based fuel cell according to claim 1, wherein: The high-temperature carbonization in step (4) is carried out under the protection of an inert gas, and the high-temperature carbonization time is 3-4 hours.

9. The method for preparing a polypyrrole-modified carbon electrode material for a bio-based fuel cell according to claim 1, wherein: The mass concentration of the hydrofluoric acid solution in step (4) is 5-12wt%.

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

Images