Aperture-adjustable porous carbon as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of electro-catalysis, and particularly relates to aperture-adjustable porous carbon as well as a preparation method and application thereof. According to the preparation method of the porous carbon with the adjustable pore diameter, polymerization of small organic molecules and hydrolytic polycondensation of silane with an oxygen group are synchronously completed in the same synthesis system, composite gel is formed, and the porous carbon material with the adjustable pore diameter is formed through heat treatment. The method has the advantages of low requirement on equipment in the preparation process, short preparation flow, simple operation, environment-friendly preparation process, and wide industrial application prospect, and is very beneficial to large-scale production.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrocatalysis, and in particular relates to porous carbon with adjustable pore size, a preparation method thereof, and an application thereof. Background Art

[0002] With the continuous advancement of industrial technology, a growing population, and the continued consumption of traditional fossil fuels, society today faces enormous challenges: insufficient sustainable energy supply, excessive greenhouse gas emissions, and a deteriorating global environment. Currently, the development of clean, renewable energy and the conversion of emitted greenhouse gases into usable fuels have become recognized as urgent tasks and important research directions worldwide, and have been hot topics of global research for over a decade.

[0003] Fuel cells, including proton exchange membrane fuel cells, alkaline fuel cells, and metal-air batteries, are a renewable energy technology that, with their outstanding advantages of high efficiency, cleanliness, and flexibility, has become a core technology in the energy revolution. In particular, in recent years, major energy-consuming countries, including China, the United States, Japan, and Europe, have been actively promoting the industrialization of fuel cells, actively improving their cost-effectiveness and reliability, and striving to achieve large-scale application in transportation, energy, and industry as soon as possible. Among these, proton exchange membrane fuel cells, which have been the subject of extensive research and have achieved initial implementation, have attracted the most attention and investment from various countries. Although fuel cell technology has made significant progress over the years, the inherent limitation of slow oxygen reduction reaction kinetics remains a major bottleneck limiting its large-scale application. Precious metal nanocatalysts and recently developed advanced transition metal catalysts remain essential key materials for fuel cells and account for a significant proportion of fuel cell costs. Therefore, improving catalyst utilization and stability are key technologies that require continuous optimization in the fuel cell field. Compared with other strategies and substrates, carbon carriers have outstanding advantages in terms of low price, outstanding conductivity, light weight and excellent dispersibility in improving catalyst dispersion and electrode reaction mass transfer kinetics. Therefore, they have also been unanimously recognized by the industry. However, the carbon carriers currently used in commercial applications are basically carbon carriers with relatively smooth surfaces, and there is still room for improvement in dispersing the active components of the catalyst. Carbon carriers with a good degree of graphitization and a through-pore structure inside can not only load nanoparticles of the active components of the catalyst, but can also be used to disperse precursors, thereby effectively hindering the migration and aggregation of nanoparticles in the process of forming catalyst particles in post-processing, and ultimately forming a highly uniform and dispersed excellent catalyst, thereby achieving a dual improvement in the activity and stability of the catalyst. However, at this stage, the preparation of porous carbon carriers generally has the problems of complex preparation processes, expensive reagents used, and serious damage to the environment. It is still a great challenge to achieve a simple and effective method to prepare graphitized carbon with controllable pore structure. Summary of the Invention

[0004] The present invention aims to provide a porous carbon with adjustable pore size, a preparation method and an application thereof.

[0005] To achieve the above purpose, the present invention adopts the following technical solutions:

[0006] A porous carbon with adjustable pore size and a preparation method thereof realizes simultaneous completion of organic small molecule polymerization and hydrolysis and polycondensation of oxygen-containing silane in the same synthesis system to form a composite gel, which is then heat-treated to form a porous carbon material with adjustable pore size.

[0007] Furthermore, organic precursor small molecules, catalysts that can catalyze the polymerization of organic precursor small molecules, and silane are dissolved in a mixed solvent that can simultaneously disperse organic precursor small molecules and silane, and then an acidic medium that controls the precursor assembly speed, silane hydrolysis and condensation rate is added to the system to achieve simultaneous assembly of organic small molecules and condensation of silane in the same system, thereby obtaining a composite gel in which organic polymers and silicone gel coexist, and then forming porous carbon with adjustable pore size through heat treatment.

[0008] Going further,

[0009] (1) Preparation of an organic small molecule polymerization system: dissolving an organic precursor small molecule in a mixed solvent capable of simultaneously dispersing the organic precursor small molecule and silane to form a uniformly dispersed solution A, and adding a catalyst capable of catalyzing the polymerization of the organic precursor small molecule to the dispersed solution A under stirring conditions, and stirring and mixing the mixture; wherein the molar ratio of the organic precursor small molecule to the catalyst capable of catalyzing the polymerization of the organic precursor small molecule is 0.1 to 20, and the mass ratio of the organic precursor small molecule to the mixed solvent is 0.1 to 0.0001;

[0010] (2) Assembly of organic small molecules and polycondensation of silane: Silane is added dropwise to solution A under stirring conditions to form a uniform solution B, and then an acid solution is added dropwise to the system, and stirring is continued to make the entire polymerization system uniformly dispersed, so that the organic small molecules and silane are in molecular-level uniform contact to form the final polymerization solution C (the stirring time for forming solution C can be 0.5-12 hours), and then the system is subjected to a hydrolysis and polycondensation reaction of silane and organic molecules at 40-180°C for 1-36 hours to form a uniform composite gel;

[0011] (3) Heat treatment of composite gel: The composite gel formed in the above (2) is freeze-dried in a vacuum, and then fully crushed after drying. After crushing, it is carbonized at 700-1600°C for 0.5-4 hours, and then cooled to room temperature to obtain a C / SiO2 composite in which the organic polymer is fully carbonized and coated on the surface of silicon oxide. After further treatment, porous carbon with adjustable pore size is obtained.

[0012] The organic precursor small molecule is one or more of dopamine, aniline, indene, fluorene, acenaphthene, thiophene, pyrrole, pyridine and derivatives of the aforementioned compounds; the oxygen-containing silane is one or more of methoxysilane, ethoxysilane, propoxysilane, butoxysilane, etc. with different numbers of oxygen groups; the mixed solvent for simultaneously dispersing the organic precursor small molecule and the silane is a water-alcohol solution system; the catalyst that can catalyze the polymerization of the organic precursor small molecule is one or more of potassium permanganate, iron salt, boron trifluoride, and aluminum trichloride.

[0013] The dispersion system obtained in step (1) is stirred and mixed at a temperature of 0-40° C. and a speed of 50-1000 rpm.

[0014] In step (2), when solution A forms solution B, the stirring rate is controlled in the range of 50-1000 rpm and the temperature range is 0-40°C; the acid solution for adjusting the pH value can be one or more of hydrochloric acid, sulfuric acid, nitric acid, and acetic acid solutions, with a concentration of 0.01-10 mol / L.

[0015] In the step (3), freeze vacuum drying is performed at a freezing temperature of -60°C to -5°C and a vacuum degree of 0.01-500Pa; the crushing is performed by ball milling, wherein the ball-to-material ratio is 30:1-1:5 and the ball milling time is 0.5-10 hours.

[0016] The carbonization treatment is carried out in a carbonizing atmosphere, wherein the carbonizing atmosphere is an inert gas and / or a reducing gas, the inert gas is one or more of nitrogen, helium, and argon, and the reducing gas is one or a mixture of hydrogen and carbon monoxide.

[0017] The C / SiO2 composite is crushed into nanopowder again, and the powder is etched with an alkaline solution or an HF acid solution at a set temperature of 25-80°C for 2-48 hours, and then repeatedly rinsed with pure water to remove silicon and other foreign atoms around the carbon to obtain the final porous carbon support.

[0018] The re-crushing can be carried out in accordance with the pulverization method described above, or by using a grinding mortar; the solution for removing silicon oxide from the crushed powder can be a strong alkaline solution, comprising a mixture of one or both of potassium hydroxide solution and sodium hydroxide solution in any proportion, with a concentration of 1 mol L -1 -5mol L -1 The removal process must be carried out with continuous stirring at a stirring rate of 100-1000 rpm and a temperature of 50-90°C. The solution for removing silicon oxide can also be a hydrofluoric acid solution with a volume concentration of 5%-30% and a temperature controlled between 20-50°C.

[0019] The method can achieve precise control of the pore size distribution in the carbon substrate, selective doping of transition metal elements or doping of non-metallic heteroatoms such as nitrogen, sulfur, phosphorus, etc. in the carbon substrate, and can prepare pore-adjustable porous carbon with good graphitization and outstanding stability.

[0020] A porous carbon prepared by the method has adjustable porous carbon particle size, internal pore structure and heteroatom doping types.

[0021] The invention discloses an application of porous carbon with adjustable pore size. The carbon material can be used as a carbon carrier in the field of various metal or metal oxide catalyst carriers, and can also be used as a carbon material in electrodes of sodium ion batteries, lithium ion batteries, etc. as an electrode material.

[0022] Compared with the existing porous carbon preparation methods, the essential characteristics and creativity of the present invention are embodied in:

[0023] The method of the present invention produces porous carbon materials with uniform and dense pore distribution, selective in-situ doping with metal or non-metallic elements (the doping elements are provided by organic precursor small molecules and catalysts), very uniform and fine particles, good carbon structure graphitization, and precisely controllable pore size and specific surface area. The porous carbon materials have a uniform and stable structure. The method is low-cost, requires simple equipment, and has a short preparation process. It has advantages over most existing methods for preparing carbon materials, specifically:

[0024] (1) The present invention simultaneously completes the polymerization of organic small molecules and the hydrolysis and condensation of silane in the same synthesis system using the same process conditions, and successfully achieves molecular-level contact and dispersion between the silane condensation product and the organic polymer macromolecule, thereby ensuring the uniformity, richness and overall permeability of the pore structure derived from the subsequent removal of silicon, and provides a structural guarantee for improving the mass transfer efficiency of carbon materials and the spatial confinement and dispersion of catalyst nanoparticles as a carbon substrate. Such an excellent pore structure can be achieved in just one step, which is completely different from other conventional methods, such as first hydrolyzing silane in a specific system, then preparing porous silica by air calcination, and then forming a template in a polymer synthesis system to form a silicon oxide surface-coated polymer, and finally obtaining a porous carbon material through a cleaning, carbonization, and etching process. The present invention greatly shortens the preparation process, reduces the process complexity, creates a through-pore structure, and is highly creative.

[0025] (2) The method of the present invention can control the thickness of the carbon layer around the pores by adjusting the ratio between the organic molecular precursor and the silane, and can also control the size of the silane hydrolysis condensation unit by adjusting process parameters such as the polymerization temperature and pH value, thereby controlling the particle size of the silicon oxide particles formed after sintering. After the silicon oxide is removed by etching, a porous carbon material with adjustable pore size is formed.

[0026] (3) The present invention can selectively polymerize organic molecular precursors containing specific groups and elements according to the target heteroatom doping during the polymerization of organic molecular precursors, so that the six-membered ring structure of carbon atoms and the in-situ doping of heteroatoms can be achieved during the subsequent carbonization of the polymer. The method of the present invention can also add specific metal salts during the polymerization process, which can achieve the coordination doping of metals and heteroatoms during the carbonization process, thereby forming the doping of heteroatoms and metal elements in one step, and can achieve the simultaneous completion of pores, heteroatoms, metal elements and graphitization during the construction of the carbon substrate. This is rarely reported in existing synthesis methods, which indirectly confirms the creativity of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Photograph of the indene polymer / silicon composite gel prepared in Example 1 of the present invention.

[0028] Figure 2 Transmission electron microscope image of the porous carbon prepared in Example 1 of the present invention.

[0029] Figure 3 X-ray diffraction curve of the porous carbon prepared in Example 1 of the present invention.

[0030] Figure 4 The discharge specific capacity and cycle stability of the porous carbon prepared in Example 1 of the present invention as the negative electrode of a sodium ion battery.

[0031] Figure 5 Transmission electron microscope image of the porous carbon prepared in Example 2 of the present invention.

[0032] Figure 6 Linear voltammetric scan curve of oxygen reduction catalyzed by porous carbon supported Pt3Co prepared in Example 2 of the present invention.

[0033] Figure 7 Linear voltammetric scanning curve of the oxygen reduction reaction catalyzed by the porous carbon prepared in Example 3 of the present invention in an alkaline solution. DETAILED DESCRIPTION

[0034] The present invention is further described below with reference to specific examples, but the present invention is not limited to the following examples. The methods described are conventional methods unless otherwise specified. The raw materials described can be obtained from public commercial sources unless otherwise specified.

[0035] The preparation process of the present invention is simple, the effective product yield is high, and the prepared porous carbon material has good porosity and through-hole structure. By selecting the structure of the organic molecular precursor and regulating the appropriate carbonization heat treatment parameters, specific heteroatom doping and a high degree of carbon graphitization can be achieved. First, a specific organic small molecule precursor that can complete polymerization with silane in a similar hydrolysis and condensation system is dissolved in a water / alcohol mixed solvent to form a uniformly dispersed solution, and a metal salt that can catalyze the polymerization of organic small molecules is added; secondly, silane is added dropwise to the above solution and continuously stirred, and then the pH value is adjusted, and the formation of a composite gel of organic polymer and silicon hydrolysis and condensation product is completed by heating and pressurizing. Finally, porous carbon can be obtained by drying, carbonizing, and etching to remove silicon oxide.

[0036] This method forms a uniformly mixed and dispersed composite gel using an organic polymer and silica gel in a single synthesis system. Silicon is then removed to form a porous carbon material with tunable pores. This method offers advantages such as simple process steps, a short flow, adjustable pore structure, and the ability to dope heteroatoms within the carbon substrate. The resulting catalyst carbon substrate has a large specific surface area, excellent graphitization, and stability, significantly outperforming commercial Pt / C catalysts. The entire synthetic route requires minimal equipment and exhibits excellent process stability, making it highly valuable for industrial application.

[0037] Example 1

[0038] 3 L of anhydrous ethanol and 1 L of deionized water were mixed and stirred at a stirring rate of 300 rpm. During the stirring process, 500 ml of indene was added. After stirring for 5 minutes, 200 ml of a solution containing 50 g of ferric chloride was added and stirred continuously to form solution A. After stirring solution A for 10 minutes, 1 L of tetraethyl silicate was added and stirred for 10 minutes to form solution B. Finally, 50 ml of 1.0 mol L -1 The hydrochloric acid solution was added dropwise to the above solution B to form the final synthetic system C. After stirring for 30 minutes, the mixture was transferred to a reactor and sealed. The hydrolysis polymerization was carried out in a blast drying oven at 150°C for 6 hours. After the reaction was completed, the mixture was air-cooled to room temperature to obtain a composite gel (see Figure 1 ).

[0039] The composite gel was placed in a stainless steel cup filled with liquid nitrogen, ensuring that the liquid nitrogen layer was higher than the gel. After freezing for 10 minutes, it was placed in a freeze vacuum dryer and vacuum dried at -50°C for 48 hours. The dried powder was crushed using a planetary ball mill with a ball-to-material ratio of 10:1 and ball milled at 1000 rpm for 30 minutes. The ball-milled powder was then subjected to 2 mol L -1The obtained porous carbon material was characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). The TEM image of the obtained porous carbon material is shown in FIG. 1, which shows that the pores are through, the voids are dense, and the whole is uniform. The graphitization degree of the porous carbon was analyzed and characterized by an X-ray diffractometer, and the test results are shown in FIG. 2. The results show that the graphitization degree of the carbon is good. Figure 2 and Figure 3 ).

[0040] Figure 2 The TEM image of the obtained porous carbon material is shown in FIG. 1, which shows that the pores are through, the voids are dense, and the whole is uniform. The graphitization degree of the porous carbon was analyzed and characterized by an X-ray diffractometer, and the test results are shown in FIG. 2. The results show that the graphitization degree of the carbon is good. Figure 3

[0041] As can be seen from FIG. 3, the obtained composite gel has good uniformity, the hydrolysis and polycondensation of tetraethyl orthosilicate are complete, the indene polymerization forms a red polymer and is uniformly dispersed in the gel system, forming a uniform composite system of silicon hydrolyzate and indene polymer, which provides a precursor guarantee for the formation of a uniform pore structure in the later carbonization. Figure 1 The TEM image of the obtained porous carbon material is shown in FIG. 1, which shows that the pores are through, the voids are dense, and the whole is uniform. The graphitization degree of the porous carbon was analyzed and characterized by an X-ray diffractometer, and the test results are shown in FIG. 2. The results show that the graphitization degree of the carbon is good. Figure 2 Figure 3 Meanwhile, the above porous carbon derived from indene was used as a negative electrode material of a sodium ion battery, and the sodium ion battery (CR2032 type) was assembled and tested. The positive electrode material was Na3V2(PO4)3, the electrolyte was 1M NaPF6 in EC:DMC (1:1 vol%), and glass fiber (Whatman GF / D) was used as a separator. The assembled battery was subjected to battery charge-discharge cycling at 0.2C, the charge-discharge curve was recorded, the corresponding charge-discharge capacity and efficiency were calculated, and the performance change of the battery was observed, and the cycle stability of the battery was obtained (see FIG. 4). As can be seen from FIG. 4, the discharge specific capacity and cycle stability of the assembled sodium ion battery, and the results show that the prepared porous carbon has good potential for electrode material application.

[0042] Figure 4 Figure 4 Example 2

[0043] Example 2

[0044] ​​​2 L of isopropanol and 4 L of deionized water were mixed and stirred at 600 rpm. During stirring, 1 L of aniline was added and stirred for 5 minutes to form Solution A. Stirring was continued for an additional 10 minutes. A catalyst solution, pre-dissolved in 300 mL of deionized water (30 g of ammonium persulfate), was added dropwise to Solution A and stirred for 15 minutes. 1.5 L of tetraethyl orthosilicate was then quickly added to Solution A and stirred for 20 minutes to form Solution B. Finally, 200 mL of acetic acid was slowly added dropwise to Solution B and stirred for 30 minutes to form the final synthetic system C. Solution C was transferred to a sealed reactor and subjected to hydrolysis and polymerization in a forced air drying oven at 100°C for 12 hours. After the reaction, the reaction mixture was air-cooled to room temperature. After the reaction, the composite gel was removed and frozen in a refrigerator. After freezing for 24 hours, it was placed in a freeze-vacuum dryer and vacuum-dried at -40°C for 24 hours. The dried powder was crushed using a planetary ball mill with a ball-to-material ratio of 5:1 and ball milled at 1000 rpm for 1 hour. The ball-milled powder was etched with a 10 vol.% HF solution at 25°C for 10 hours, and then the carbon material was collected by centrifugation at a centrifugal speed of 8000 rpm for 10 minutes. The carbon collected by centrifugation was filtered and rinsed with deionized water to obtain porous carbon without silicon residue. Finally, it was vacuum dried at 100°C for 6 hours to obtain aniline-derived nitrogen-doped porous carbon material (see Figure 5 ),

[0045] Depend on Figure 5 The transmission electron microscopy images shown indicate the successful polymerization of aniline and the formation of a porous structure.

[0046] The carbon prepared above was used as a carbon substrate. The carbon, which had been impregnated with a mixed solution of chloroplatinic acid (H2PtCl6) and cobalt nitrate, was vacuum dried and then subjected to high-temperature reduction and alloying in a H2 / Ar atmosphere with a hydrogen volume ratio of 10%. The heat treatment temperature was 600°C for 2 hours. After cooling, a nitrogen-doped carbon-supported platinum-cobalt alloy nanocatalyst was obtained. The prepared catalyst was subjected to a linear voltammetry scan in a 0.1M HClO4 acidic electrolyte at a scan rate of 10 mV / s over a scan range of 0.1-1.1 V relative to standard hydrogen potential. The test curve is shown in FIG. Figure 6 The results shown indicate a half-wave potential exceeding 0.9 V vs. RHE, demonstrating the outstanding advantages of porous carbon as a catalyst support.

[0047] Example 3

[0048] 1 liter of methanol and 1 liter of deionized water were mixed and stirred at 500 rpm. 2 liters of thiophene were added during stirring and stirred for 5 minutes to form Solution A. Stirring continued for an additional 10 minutes. Ice cubes containing 100 g of ammonium persulfate and 300 g of deionized water were mixed and added to Solution A. Stirring continued for 5 minutes. 1 liter of tetraethyl silicate was quickly added to Solution A and stirred for 20 minutes to form Solution B. Finally, 2 liters of phosphoric acid solution was added to Solution B and stirred until the ice cubes were completely dissolved to form the final polymerization solution C. Stirring continued for 30 minutes, then the mixture was transferred to a sealed reactor and subjected to hydrolysis polymerization in a forced air drying oven at 180°C for 8 hours. After the reaction, the reaction mixture was air-cooled to room temperature. After the reaction, the composite gel was removed and frozen in a refrigerator. After freezing for 24 hours, it was placed in a freeze-vacuum dryer and vacuum-dried at -60°C for 30 hours. The dried powder was crushed in a planetary ball mill with a ball-to-material ratio of 2:1 and ball-milled at 300 rpm for 2 hours. The ball-milled powder was etched with a 10 vol.% HF solution at 25°C for 20 hours. The carbon material was then collected by centrifugation at 10,000 rpm for 5 minutes. The collected carbon was then filtered and rinsed with deionized water to obtain porous carbon free of silicon residues. Finally, the product was vacuum-dried at 90°C for 12 hours to obtain a polythiophene-derived porous carbon material doped with phosphorus and sulfur.

[0049] The prepared carbon was used as an oxygen reduction catalyst in an oxygen reduction catalytic reaction. The prepared porous carbon was dispersed in ethanol to form a catalyst slurry with a concentration of 5 mg / ml. The catalyst slurry was drop-coated on a rotating disk electrode so that the catalyst loading on the electrode was 400 mg / cm2. After air drying, a cyclic voltammetry curve was scanned in a 0.1M KOH alkaline electrolyte at a scan rate of 10 mV / s in a scan range of 0.15-1.15 V relative to standard hydrogen potential. The scanning curve is shown in FIG. Figure 7 As shown in the figure, it can be seen that the cyclic voltammetry scan curve of the prepared nitrogen and phosphorus doped porous carbon in oxygen-saturated 0.1M KOH shows an obvious oxygen reduction peak at 0.8V vs. RHE, demonstrating the feasibility of porous carbon as an independent catalyst and can be applied to metal-air batteries as a cathode catalyst material.

Claims

1. A method for preparing porous carbon with adjustable pore size, characterized in that: The polymerization of organic small molecules and the hydrolysis and condensation of oxygen-containing silanes are simultaneously completed in the same synthetic system to form a composite gel, which is then heat-treated to form a porous carbon material with adjustable pore size.

2. The method for preparing porous carbon with adjustable pore size according to claim 1, characterized in that: Organic precursor small molecules, catalysts that can catalyze the polymerization of organic precursor small molecules, and silane are dissolved in a mixed solvent that can simultaneously disperse organic precursor small molecules and silane. Then, an acidic medium that controls the precursor assembly speed, silane hydrolysis and condensation rate is added to the system to achieve simultaneous assembly of organic small molecules and condensation of silane in the same system, thereby obtaining a composite gel in which organic polymers and silicone gel coexist, which is then formed into porous carbon with adjustable pore size through heat treatment.

3. The method for preparing porous carbon with adjustable pore size according to claim 2, wherein: (1) Preparation of an organic small molecule polymerization system: dissolving an organic precursor small molecule in a mixed solvent capable of simultaneously dispersing the organic precursor small molecule and silane to form a uniformly dispersed solution A, and adding a catalyst capable of catalyzing the polymerization of the organic precursor small molecule to the dispersed solution A under stirring conditions, and stirring and mixing the mixture; wherein the molar ratio of the organic precursor small molecule to the catalyst capable of catalyzing the polymerization of the organic precursor small molecule is 0.1 to 20, and the mass ratio of the organic precursor small molecule to the mixed solvent is 0.1 to 0.0001; (2) Assembly of organic small molecules and polycondensation of silane: Silane is added dropwise to solution A under stirring conditions to form a uniform solution B, and then an acid solution is added dropwise to the system, and stirring is continued to make the entire polymerization system uniformly dispersed, so that the organic small molecules and silane are in molecular-level uniform contact to form the final polymerization solution C. Subsequently, the system is subjected to a hydrolysis and polycondensation reaction of silane and organic molecules at 40-180°C for 1-36 hours to form a uniform composite gel; (3) Heat treatment of composite gel: The composite gel formed in the above (2) is freeze-dried in a vacuum, and then fully crushed after drying. After crushing, it is carbonized at 700-1600°C for 0.5-4 hours, and then cooled to room temperature to obtain a C / SiO2 composite in which the organic polymer is fully carbonized and coated on the surface of silicon oxide. After further treatment, porous carbon with adjustable pore size is obtained.

4. The method for preparing porous carbon with adjustable pore size according to claim 3, wherein: The organic precursor small molecule is one or more of dopamine, aniline, indene, fluorene, acenaphthene, thiophene, pyrrole, pyridine and derivatives of the aforementioned compounds; the oxygen-containing silane is one or more of methoxysilane, ethoxysilane, propoxysilane and butoxysilane; the mixed solvent for simultaneously dispersing the organic precursor small molecule and silane is a water-alcohol solution system; the catalyst that can catalyze the polymerization of the organic precursor small molecule is one or more of potassium permanganate, iron salt, boron trifluoride and aluminum trichloride.

5. The method for preparing porous carbon with adjustable pore size according to claim 3 or 4, characterized in that: The dispersion system obtained in step (1) is stirred and mixed at a temperature of 0-40° C. and a speed of 50-1000 rpm.

6. The method for preparing porous carbon with adjustable pore size according to claim 3, wherein: In step (2), when solution A forms solution B, the stirring rate is controlled in the range of 50-1000 rpm and the temperature range is 0-40°C; the acid solution for adjusting the pH value can be one or more of hydrochloric acid, sulfuric acid, nitric acid, and acetic acid solutions, with a concentration of 0.01-10 mol / L.

7. The method for preparing porous carbon with adjustable pore size according to claim 3, wherein: In the step (3), freeze vacuum drying is performed at a freezing temperature of -60°C to -5°C and a vacuum degree of 0.01-500Pa; the crushing is performed by ball milling, wherein the ball-to-material ratio is 30:1-1:5 and the ball milling time is 0.5-10 hours.

8. The method for preparing porous carbon with adjustable pore size according to claim 3, wherein: The C / SiO2 composite is crushed into nanopowder again, and the powder is etched with an alkaline solution or an HF acid solution at a set temperature of 25-80°C for 2-48 hours, and then repeatedly rinsed with pure water to remove silicon and other unstable atoms around the carbon to obtain the final porous carbon support.

9. A porous carbon with adjustable pore size prepared by the method of claim 1, characterized in that: The porous carbon prepared by the method of claim 1 has adjustable porous carbon particle size, internal pore structure and heteroatom doping type.

10. A use of the porous carbon with adjustable pore size according to claim 9, characterized in that: The porous carbon with adjustable pore size is used as a carbon carrier or electrode material.

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