Phenolic resin-based nitrogen-doped mesoporous carbon as well as preparation method and application thereof

Abstract

The invention discloses phenolic resin-based nitrogen-doped mesoporous carbon as well as a preparation method and application thereof. According to the invention, phenolic resin is used as a carbon source, mesoporous carbon is prepared through rapid carbonization and activation by using a template method and a high-temperature thermal shock technology, accurate regulation and control of nitrogen doping and mesoporous structures are realized in the process, and the specific surface area, conductivity and thermal stability of mesoporous carbon are improved; the electrochemical reaction activity and stability of the mesoporous carbon carrier are remarkably improved, and the problems of long activation time, non-uniform pore structure and the like of a traditional method are solved, so that the application range of the mesoporous carbon carrier in the fields of electrochemical energy storage and catalysis is widened.

Description

Technical Field

[0001] The present invention relates to the technical field of functional carbon materials, and in particular, to a phenolic resin-based nitrogen-doped mesoporous carbon and a preparation method and application thereof. Background Art

[0002] Mesoporous carbon has a unique pore structure and a high specific surface area, and is widely used in fields such as fuel cells, supercapacitors, and alkali metal batteries. The raw materials of mesoporous carbon are widely sourced, such as coal and its derivatives, biomass, polymer resins, etc. Among them, phenolic resin has excellent mechanical properties, thermal stability, and chemical corrosion resistance. Due to the abundant hydroxyl and methyl groups in its molecular structure, carbon materials with unique pore structures and functionalized surfaces can be prepared through techniques such as the template method and chemical activation method, and it is an important carbon source for preparing mesoporous carbon.

[0003] By means of heteroatom doping and other methods, the electronic structure and surface chemical properties of mesoporous carbon can be improved. Nitrogen-doped mesoporous carbon has become a research hotspot in the fields of new energy storage and catalysis due to its abundant active sites and excellent electrical conductivity. For example, in supercapacitors, the high specific surface area and pseudocapacitance active sites significantly improve the capacitance; in metal-air batteries and fuel cells, as a bifunctional catalyst, it can effectively catalyze the oxygen reduction and oxygen evolution reactions. In addition, nitrogen-doped mesoporous carbon can also be used in lithium / sodium ion batteries, significantly improving the cycle performance and kinetic characteristics.

[0004] However, at present, nitrogen-doped mesoporous carbon materials still face challenges such as insufficient precision in pore structure regulation, complex preparation processes, and poor long-term cycle stability. Summary of the Invention

[0005] The present invention aims to solve at least one of the technical problems in the related art to some extent.

[0006] To this end, an embodiment of the present invention provides a phenolic resin-based nitrogen-doped mesoporous carbon and a preparation method and application thereof.

[0007] In a first aspect, the present invention provides a preparation method of a phenolic resin-based nitrogen-doped mesoporous carbon, including the following steps:

[0008] (a) Adding a template agent to a solution of phenolic resin and stirring evenly to obtain a gel-like mixture;

[0009] (b) Adding a curing agent to the gel-like mixture and curing to obtain a cured sample;

[0010] (c) Laying the cured sample powder on a carbon cloth electrode and performing high-temperature thermal shock carbonization and activation treatment to obtain a preliminary mesoporous carbon;

[0011] (d) Washing and drying the preliminary mesoporous carbon sample powder to obtain mesoporous carbon.

[0012] Further, the mass ratio of the phenolic resin to the templating agent is (1-4):1.

[0013] Further, the particle size of the templating agent is 5-10 nm.

[0014] Further, the templating agent includes one or more of potassium hydroxide, potassium chloride, potassium carbonate, sodium hydroxide, sodium carbonate, and sodium chloride.

[0015] Further, the addition amount of the curing agent is 0.5%-15% of the mass of the phenolic resin.

[0016] Further, the curing agent includes one or more of ammonium chloride, ammonium sulfate, hexamethylenetetramine, triethylamine, dicyandiamide, urea, and amino resin.

[0017] Further, the power of the high-temperature thermal shock treatment is 40-48 kW, and the time is 10-30 s.

[0018] Further, the preparation process of the phenolic resin solution includes the following steps:

[0019] Drop 15%-20% of the ammonia water by mass of phenol into the molten phenol, and stir while dropping.

[0020] Under the condition of a 65°C water bath, add a 37% formaldehyde solution accounting for 50%-60% of the mass of phenol, and react for 1-2 h.

[0021] Under the condition of a 70°C water bath, add a 37% formaldehyde solution accounting for 50%-60% of the mass of phenol, and react for 1-3 h.

[0022] Cool to 45-55°C, and add a solvent to obtain a solution of the phenolic resin.

[0023] In a second aspect, the present invention provides mesoporous carbon prepared by the preparation method provided in the first aspect above.

[0024] In a third aspect, the present invention provides the application of the mesoporous carbon prepared by the preparation method provided in the first aspect above or the mesoporous carbon provided in the second aspect above in a catalyst carrier.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] The present invention uses phenolic resin as a carbon source, and prepares mesoporous carbon through carbonization and activation treatment by high-temperature thermal shock technology. During this process, precise regulation of nitrogen doping and mesoporous structure is achieved, the specific surface area, conductivity and thermal stability of the mesoporous carbon are improved, the electrochemical reaction activity and stability of the mesoporous carbon carrier are significantly enhanced, and problems such as long activation time and uneven pore structure in traditional methods are solved, thereby broadening its application scope in the fields of electrochemical energy storage and catalysis.

[0027] In the process of preparing phenolic resin in the present invention, ammonia water is added first and then formaldehyde is added to prepare a thermosetting polymer. The phenolic resin with thermosetting properties will not deform during the subsequent high-temperature carbonization process, ensuring the stability of the pore structure and morphology of the mesoporous carbon; if formaldehyde is added first and then ammonia water is added, the prepared thermoplastic polymer will deform during the high-temperature carbonization process and the pore structure will collapse.

[0028] The present invention realizes the nitrogen doping of the precursor by adding a nitrogen-containing curing agent, improving the conductivity of the final product mesoporous carbon; adopts the high-temperature shock method to use an instantaneous electric heating device to achieve rapid carbonization of the resin precursor. The activator instantly melts into small droplets, and the instantaneous Joule heating during high-temperature rapid quenching can effectively make the phenolic resin generate a large number of pores with uniform size distribution. The phenolic resin is more likely to interact with the activator, thereby obtaining mesoporous carbon with an ideal porous structure and high specific surface area. This method solves the problems existing in traditional methods, such as long activation time, high cost, large and uneven pore structure, and relatively low specific surface area. Description of the Drawings

[0029] The above-mentioned and / or additional aspects and advantages of the present invention will become obvious and easy to understand from the following description of the embodiments in conjunction with the drawings, where:

[0030] Figure 1 For the N of Examples 1-4 and Comparative Examples 2 and 3 2 Adsorption-desorption curve.

[0031] Figure 2 For the thermogravimetric analysis curves of Examples 1-4 and Comparative Examples 2 and 3.

[0032] Figure 3 For the scanning electron microscope pictures of Example 1 and Comparative Examples 1-3.

[0033] Figure 4 For the Raman spectra of Example 1 and Comparative Example 3.

[0034] Figure 5 For the infrared spectra of Example 1 and Comparative Example 1.

[0035] Figure 6 For the polarization curves of Example 1 and Comparative Example 1.

[0036] Figure 7 Cyclic voltammograms of Example 1 and Comparative Example 3. Detailed implementation manners

[0037] Embodiments of the present invention will be described in detail below. Examples of the embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the accompanying drawings are exemplary and are intended to explain the present invention, and should not be construed as limiting the present invention.

[0038] The phenolic resin-based nitrogen-doped mesoporous carbon and its preparation method and application proposed by the present invention will be described below with reference to the accompanying drawings.

[0039] The preparation method of the phenolic resin-based nitrogen-doped mesoporous carbon includes the following steps:

[0040] (a) Adding a templating agent to a solution of phenolic resin and stirring evenly to obtain a gel-like mixture;

[0041] (b) Adding a curing agent to the gel-like mixture and curing to obtain a cured sample;

[0042] (c) Laying the cured sample powder on a carbon cloth electrode and performing high-temperature thermal shock carbonization and activation treatment to obtain a preliminary mesoporous carbon;

[0043] (d) Washing and drying the preliminary mesoporous carbon sample powder to obtain mesoporous carbon.

[0044] Among them, in step (a), the particle size of the templating agent is 5-10 nm. When the particle size of the templating agent is within a suitable range, it can ensure that the pore size range of the mesoporous carbon sample is distributed between 3-20 nm. The precise pore structure is beneficial to obtaining high-performance mesoporous carbon samples and broadening their application scope; when the pore size of the templating agent is too large, the pore size range distribution of the mesoporous carbon sample is relatively wide, the pore structure size is large, and the specific surface area is small, which is not conducive to subsequent applications; when the pore size of the templating agent is too small, the cost of the templating agent will increase, and the pore structure of the mesoporous carbon sample is microporous, which is also not conducive to subsequent applications. The mass ratio of the phenolic resin to the templating agent is (1-4):1, and the templating agent includes one or more of potassium hydroxide, potassium chloride, potassium carbonate, sodium hydroxide, sodium carbonate, and sodium chloride.

[0045] The preparation process of the phenolic resin solution includes the following steps:

[0046] (1) Adding 15%-20% of the ammonia water by the mass of phenol dropwise to the molten phenol while stirring;

[0047] (2) Under the condition of a 65°C water bath, adding 50%-60% of the formaldehyde solution with a concentration of 37% by the mass of phenol and reacting for 1-2 h;

[0048] (3) Under the condition of a 70°C water bath, add a 37% formaldehyde solution with a mass of 50% - 60% of the phenol, and react for 1 - 3 h;

[0049] (4) Cool to 45 - 55°C, and add a solvent to obtain a solution of phenolic resin.

[0050] Among them, the melting temperature of phenol in step (1) is not specifically limited, as long as it can melt phenol. In some embodiments, the concentration of ammonia water is 25%.

[0051] In step (2), the reaction is carried out under the condition of a 65°C water bath. At a lower temperature, the reaction rate between phenol and formaldehyde is slower, which helps to avoid the occurrence of side reactions. At this temperature, mainly the condensation reaction between phenol and formaldehyde occurs to form a preliminary structure of phenolic resin. The reaction at this stage is relatively mild, which is beneficial to controlling the molecular weight and structural uniformity of the resin.

[0052] In step (3), the reaction is carried out under the condition of a 70°C water bath. After the temperature is raised to 70°C, the reaction rate increases, which helps to further promote the resin cross-linking reaction, increase the cross-linking points between molecules, and form a thermosetting structure. At this time, the reaction rate increases, which helps to increase the solid content of the resin and promote the completion of the reaction, thereby enhancing the performance of the resin.

[0053] The present invention adopts a strategy of reacting at two temperatures, which helps to optimize different stages of the resin. When reacting at 65°C, the phenolic resin is not completely cross-linked, so it has certain processability. After the reaction at 70°C is completed, the cross-linking degree of the phenolic resin increases significantly, forming a thermosetting resin with stronger thermal stability and mechanical strength.

[0054] In step (4), the addition amount of the solvent is 4 - 6 times the mass of the phenolic resin. In some embodiments, the solvent is an ethanol solution.

[0055] In the process of preparing phenolic resin in the present invention, ammonia water is added first and then formaldehyde, and a thermosetting high molecular polymer is prepared. The thermosetting phenolic resin will not deform during the subsequent high-temperature carbonization process, ensuring the stability of the mesoporous carbon pore structure and morphology, and preventing the collapse and shrinkage of the pore structure.

[0056] In step (b), the addition amount of the curing agent is 0.5% - 15% of the mass of the phenolic resin. The addition amount of the curing agent within a suitable range enables the phenolic resin to have a suitable molecular weight and good mechanical properties. When the addition amount of the curing agent is excessive, the reaction of the phenolic resin is too fast, resulting in uneven curing on the resin surface, or even local over-curing, increasing the thermal stress, brittleness and internal stress of the product, and affecting the mechanical properties and surface quality of the product. When the addition amount of the curing agent is too small, the cross-linking reaction of the phenolic resin is incomplete, resulting in the inability to complete the curing process thoroughly, and affecting the heat resistance and chemical resistance of the product. The curing agent includes one or more of ammonium chloride, ammonium sulfate, hexamethylenetetramine, triethylamine, dicyandiamide, urea, amino resin, and the curing agent plays the role of curing and nitrogen doping. In some embodiments, after adding the curing agent to the gel-like mixture, it is placed in a blast air direction at 100 - 120 °C for stable curing for 10 - 16 h.

[0057] In the present invention, nitrogen doping of the precursor is achieved by adding a nitrogen-containing curing agent, improving the conductivity of the final product mesoporous carbon.

[0058] In step (c), the cured sample is ground into powder, the mixed powder is evenly spread on the carbon cloth electrode, and the carbon cloth electrode loaded with the mixed powder is connected to a DC source with a current pulse in an instantaneous electric heating device, and is protected and heated in an inert gas (N 2 )). The voltage for the high-temperature thermal shock treatment is 380 V, the current is 25 - 35 A, the power is 40 - 48 kW, and the time is 10 - 30 s.

[0059] During the carbonization and activation of mesoporous carbon, high-temperature shock quickly melts the template agent into small droplets instantaneously, which can interact fully with the phenolic resin, thereby obtaining mesoporous carbon with controllable and evenly distributed pore structures. The rapid high-temperature shock method is used to realize the rapid carbonization and activation of the resin precursor by an instantaneous electric heating device, thereby obtaining mesoporous carbon with an ideal mesoporous structure and high specific surface area, solving the problems existing in the traditional method, such as long activation time, high cost, large and uneven pore structures, and relatively low specific surface area.

[0060] The present invention uses phenolic resin as a carbon source, and prepares mesoporous carbon by rapid carbonization and activation through a high-temperature thermal shock method. During this process, precise regulation of nitrogen doping and mesoporous structure is achieved, improving the specific surface area, conductivity and thermal stability of mesoporous carbon, significantly enhancing the electrochemical reaction activity and stability of the mesoporous carbon carrier, and thus broadening its application scope in the fields of electrochemical energy storage and catalysis.

[0061] The present invention will be described below in conjunction with specific embodiments. The test materials and reagents used in the following embodiments can be obtained from commercial sources without special instructions. For those not specifying specific technologies or conditions in the embodiments, they can all be carried out according to the technologies or conditions described in the literature in this field or according to the product specifications.

[0062] Example 1

[0063] Preparation of phenolic resin solution:

[0064] Weigh 40.0 g of phenol with an electronic balance, place it in an oven at 60 °C, heat it until molten, and stir and dissolve it with a stirring paddle at 200 rpm. Then, slowly drip 25% ammonia water within 15 min using a peristaltic pump. The added mass of ammonia water is 15% of the mass of phenol, and keep stirring.

[0065] Place the above slurry in a constant temperature water bath, heat it up to 65 °C, and quickly add 37% formaldehyde solution. The mass of the formaldehyde solution is 55% of the mass of phenol, and react at a constant temperature for 1 h.

[0066] Then heat it up to 70 °C, quickly add 37% formaldehyde solution. The mass of the formaldehyde solution is 55% of the mass of phenol, and react at a constant temperature for 2 h, then stop heating.

[0067] Cool the temperature to 50 °C, and add ethanol with a mass 5 times that of the phenolic resin to obtain a phenolic resin solution.

[0068] Preparation of mesoporous carbon:

[0069] Weigh 12.0 g of phenolic resin solution with an electronic balance, add template agent potassium chloride with a particle size of 5 nm. The mass ratio of phenolic resin to template agent is 1:3, and quickly stir with a stirring paddle until uniform to obtain a gel-like mixture.

[0070] Add curing agent hexamethylenetetramine with a mass of 3% of the phenolic resin to the gel-like mixture, and place it in a forced air oven at 120 °C for stable curing for 12 h.

[0071] Grind the cured sample into powder, evenly spread the mixed powder on a carbon cloth electrode. Connect the carbon cloth electrode loaded with the mixed powder to a DC source with a current pulse in an instantaneous electric heating device, and protect and heat it in an inert gas (N 2 )). The voltage for high-temperature thermal shock treatment is 380 V, the current is 25 - 35 A, the power is 40 kW, and the time is 20 s.

[0072] Wash the material with deionized water multiple times by ultrasonic method, filter it, and dry it at 100 °C for 48 h to obtain phenolic resin-based mesoporous carbon.

[0073] Preparation of mesoporous carbon@Pt catalyst electrode:

[0074] Weigh 500 mg of mesoporous carbon using an electronic balance, disperse it in an ethanol - aqueous solution (the volume percentage of ethanol is 20%), add a certain amount of chloroplatinic acid, a precious metal precursor with a mass percentage of 40%, and stir to dissolve and mix for 30 min; then add an excess of reducing agent NaBH 4 0.5 g, and an appropriate amount of charged surfactant PPh 3 0.1 g;

[0075] Under ultrasonic assistance with a power of 200 W, promote the reduction reaction and the dispersion of raw materials to obtain a catalyst slurry. After centrifugal washing with deionized water 4 times and vacuum drying at 60 °C for 12 h, a catalyst sample is obtained;

[0076] Weigh 5 mg of the catalyst, successively add 1 ml of 5% Nafion solution, 250 μl of ultrapure water, and 250 μl of isopropanol to the catalyst, and ultrasonicate for 30 min with a power of 200 W to make the slurry fully mixed and uniform. Keep the water bath temperature less than 20 °C during the ultrasonic process;

[0077] According to the range of catalyst loading on the electrode surface being 100 μg / cm 2 , take an appropriate amount of the well - dispersed slurry and evenly drip - coat it onto the surface of a smooth and clean disk electrode in two times, and let it dry naturally and completely to be used as a working electrode.

[0078] Example 2

[0079] Preparation of phenolic resin solution:

[0080] Weigh 40.0 g of phenol using an electronic balance, place it in an oven at 60 °C, heat it to melt, and stir - dissolve it with a stirring paddle at 200 rpm. Then, slowly drip 25% ammonia water within 15 min using a peristaltic pump. The added mass of ammonia water is 20% of the mass of phenol, and keep stirring;

[0081] Place the above - mentioned slurry in a constant - temperature water bath, heat it up to 65 °C, and quickly add 37% formaldehyde solution. The mass of the formaldehyde solution is 60% of the mass of phenol, and react at a constant temperature for 1 h;

[0082] Then heat it up to 70 °C, quickly add 37% formaldehyde solution. The mass of the formaldehyde solution is 50% of the mass of phenol, and react at a constant temperature for 2 h, then stop heating;

[0083] Cool the temperature to 50 °C, and add ethanol with a mass 5 times that of the phenolic resin to obtain a phenolic resin solution.

[0084] Preparation of mesoporous carbon:

[0085] Weigh 12.0 g of phenolic resin solution with an electronic balance, add the templating agent potassium hydroxide, and the mass ratio of phenolic resin to templating agent is 1:2. Stir quickly with a stirring paddle until uniform to obtain a gel-like mixture;

[0086] Add hexamethylenetetramine, which is 3% of the mass of phenolic resin, as the curing agent to the gel-like mixture, and place it in a forced-air oven at 120 °C for stable curing for 12 h;

[0087] Grind the cured sample into powder, evenly spread the mixed powder on the carbon cloth electrode, connect the carbon cloth electrode loaded with the mixed powder to a DC source with current pulses in an instantaneous electric heating device, and protect and heat it in an inert gas (N 2 ). The voltage for high-temperature thermal shock treatment is 380 V, the current is 25 - 35 A, the power is 40 kW, and the time is 20 s;

[0088] Wash the material with deionized water and dilute hydrochloric acid in turn by ultrasonic method for multiple times, filter, and dry at 100 °C for 48 h to obtain phenolic resin-based mesoporous carbon.

[0089] The preparation of the mesoporous carbon@Pt catalyst electrode is the same as that in Example 1.

[0090] Example 3

[0091] Preparation of phenolic resin solution:

[0092] Weigh 40.0 g of phenol with an electronic balance, place it in an oven at 60 °C, heat it to melt, and stir and dissolve it with a stirring paddle at 200 rpm. Then slowly drip 25% ammonia water within 15 min with a peristaltic pump. The added mass of ammonia water is 15% of the mass of phenol, and keep stirring;

[0093] Place the above slurry in a constant-temperature water bath, heat it to 65 °C, and quickly add 37% formaldehyde solution. The mass of the formaldehyde solution is 50% of the mass of phenol, and react at a constant temperature for 1 h;

[0094] Then heat it up to 70 °C, quickly add 37% formaldehyde solution. The mass of the formaldehyde solution is 60% of the mass of phenol, and react at a constant temperature for 2 h, then stop heating;

[0095] Cool the temperature to 50 °C, and add ethanol with a mass 5 times that of the phenolic resin to obtain the phenolic resin solution.

[0096] Preparation of mesoporous carbon:

[0097] Weigh 12.0 g of phenolic resin solution with an electronic balance, add potassium carbonate with a particle size of 10 nm as the templating agent. The mass ratio of phenolic resin to templating agent is 1:4. Stir quickly with a stirring paddle until uniform to obtain a gel-like mixture;

[0098] Add a curing agent urea with a mass of 3% of the phenolic resin to the gel-like mixture, and place it in a 120 °C blast air box for stable curing for 12 h;

[0099] Grind the cured sample into powder, evenly spread the mixed powder on the carbon cloth electrode, connect the carbon cloth electrode loaded with the mixed powder to a DC source with current pulses in an instantaneous electric heating device, and protect and heat it in an inert gas (N 2 ). The voltage for high-temperature thermal shock treatment is 380 V, the current is 25 - 35 A, the power is 40 kW, and the time is 15 s;

[0100] Wash the material with deionized water and dilute hydrochloric acid in turn by ultrasonic method for multiple times, filter and dry it at 100 °C for 48 h to obtain phenolic resin-based mesoporous carbon.

[0101] The preparation of the mesoporous carbon@Pt catalyst electrode is the same as that in Example 1.

[0102] Example 4

[0103] Preparation of the phenolic resin solution:

[0104] Weigh 40.0 g of phenol with an electronic balance, place it in a 60 °C oven, heat it to melt, and stir and dissolve it with a stirrer paddle at 200 rpm. Then, slowly drip 25% ammonia water within 15 min with a peristaltic pump. The added mass of ammonia water is 20% of the mass of phenol, and keep stirring;

[0105] Place the above slurry in a constant temperature water bath, heat it up to 65 °C, quickly add 37% formaldehyde solution. The mass of the formaldehyde solution is 50% of the mass of phenol, and react at a constant temperature for 2 h;

[0106] Then heat it up to 70 °C, quickly add 37% formaldehyde solution. The mass of the formaldehyde solution is 50% of the mass of phenol, and react at a constant temperature for 1 h, then stop heating;

[0107] Cool the temperature to 50 °C, and add ethanol with a mass 4 times that of the phenolic resin to obtain the phenolic resin solution.

[0108] Preparation of mesoporous carbon:

[0109] Weigh 12.0 g of the phenolic resin solution with an electronic balance, add a template agent sodium carbonate with a particle size of 10 nm. The mass ratio of the phenolic resin to the template agent is 1:3, and quickly stir with a stirrer paddle until it is uniform to obtain a gel-like mixture;

[0110] Add a curing agent ammonium sulfate with a mass of 5% of the phenolic resin to the gel-like mixture, and place it in a 120 °C blast air box for stable curing for 12 h;

[0111] The solidified sample was ground into powder, and the mixed powder was evenly spread on a carbon cloth electrode. The carbon cloth electrode loaded with the mixed powder was connected to a DC source with a current pulse in an instantaneous electric heating device and heated under the protection of an inert gas (N 2 ). The voltage for the high-temperature thermal shock treatment was 380 V, the current was 25 - 35 A, the power was 45 kW, and the time was 20 s;

[0112] The material was washed several times with deionized water and dilute hydrochloric acid by ultrasonic method, and dried at 100 °C for 48 h after filtration to obtain phenolic resin-based mesoporous carbon.

[0113] The preparation of the mesoporous carbon@Pt catalyst electrode was the same as that in Example 1.

[0114] Comparative Example 1

[0115] The difference from Example 1 was that no nitrogen-containing curing agent was used, and sodium silicate was used as the curing agent for phenolic resin.

[0116] Comparative Example 2

[0117] The difference from Example 1 was that the preparation method of the phenolic resin-based mesoporous carbon did not involve carbonization and activation treatment through a high-temperature thermal shock process, and other steps were the same. The carbonization process of this comparative example was as follows: The solidified sample was ground into powder, placed in a high-temperature tube furnace, and carbonized in a nitrogen atmosphere. The nitrogen flow rate was 50 mL / min, the carbonization temperature was 1000 °C, the heating rate was 10 °C / min, and the carbonization time was 3 h, so as to carbonize the solidified sample.

[0118] Comparative Example 3

[0119] Preparation of phenolic resin solution:

[0120] Weighed 40.0 g of phenol with an electronic balance, placed it in an oven at 60 °C, heated it to melt, and stirred and dissolved it with a stirrer paddle at 200 rpm. Then, a 37% formaldehyde solution with a mass 60% of that of phenol was quickly added and stirred evenly. Then, 37% formaldehyde solution (50% of the mass of phenol) and 25% ammonia water (15% of the mass of phenol) were slowly added dropwise respectively, and the dropping times were 15 min and 60 min respectively. The above slurry was placed in a constant temperature water bath, heated to 65 °C, and reacted at a constant temperature for 1 h; then heated to 70 °C and reacted at a constant temperature for 2 h, and the heating was stopped; when the temperature was cooled to 50 °C, ethanol with a mass 5 times that of the phenolic resin was added to obtain a phenolic resin solution.

[0121] The preparation of the mesoporous carbon and the preparation process of the mesoporous carbon@Pt catalyst were the same as those in Example 1.

[0122] Test Example 1

[0123] The mesoporous carbon prepared in Examples 1-4 and Comparative Examples 2 and 3 of this application was tested for specific surface area, average pore diameter, and pore volume using the BET adsorption method, and the thermal decomposition temperature was tested using thermogravimetry. Among them, the test method for the thermal decomposition temperature was as follows: An appropriate amount of the sample was weighed and placed in the test crucible of a thermogravimetric analyzer, and nitrogen was used as the working gas. The sample was heated from room temperature to the end temperature of 800 °C at a heating rate of 10 °C / min, and the sample temperature-mass curve was recorded. The test data results are shown in Table 1 below. The N 2 adsorption and desorption curves of Figure 1 are as shown in Figure 2 . The thermogravimetric analysis curves of Examples 1-4 and Comparative Examples 2 and 3 are as shown in

[0124] Table 1:

[0125]

[0126] According to Table 1 and Figure 1 and Figure 2 , it can be seen that the specific surface area of the mesoporous carbon prepared in Examples 1-4 is larger than that of Comparative Examples 2 and 3, and the thermal stability of the mesoporous carbon prepared in Examples 1-4 is better than that of Comparative Examples 2 and 3.

[0127] From the comparison of the sample data of Example 1 and Comparative Example 2, it can be seen that through the high-temperature thermal shock carbonization and activation process, the pore structure properties of phenolic resin-based mesoporous carbon can be improved. Compared with the traditional carbon activation method, the products obtained by the high-temperature thermal shock method have obvious advantages, such as easy operation, short process, and high product performance.

[0128] From the comparison of the sample data of Examples 1-4, it can be seen that the process parameters in the preparation process, such as the heating power and time during the high-temperature thermal shock treatment, the reaction time of phenolic resin, the addition amounts of formaldehyde and ammonia water, the template agent, and the addition amount of curing agent, etc., have an impact on the property parameters such as the specific surface area, pore volume, pore size distribution, and stability of phenolic resin-based mesoporous carbon.

[0129] Test Example 2

[0130] The mesoporous carbon prepared in Example 1 and Comparative Examples 1-3 was tested by scanning electron microscopy, and the test results are as shown in Figure 3 . According to Figure 3 , it can be seen that the mesoporous carbon sample of Example 1 has the best three-dimensional cross-channel connectivity and surface morphology; for the mesoporous carbon sample of Comparative Example 2 prepared by the traditional high-temperature carbonization method, there is adhesion on the surface and the pore structure is not clear; for the mesoporous carbon sample of Comparative Example 3 with thermoplasticity, condensation polymerization and pore structure collapse occur, which is not conducive to improving the specific surface area of the product.

[0131] Test Example 3

[0132] The mesoporous carbons prepared in Examples 1 to 4 and Comparative Examples 1 to 3 were subjected to conductivity tests on a Keithley four-probe conductivity measuring instrument by the four-probe method. The test results are shown in Table 2 below. Raman spectroscopy tests were performed on the mesoporous carbons of Example 1 and Comparative Example 3, and the test results are as Figure 4 shown; infrared spectroscopy tests were performed on the mesoporous carbons of Example 1 and Comparative Example 1, and the test results are as Figure 5 shown.

[0133] Table 2:

[0134] Grouping Conductivity (S / cm) Example 1 104 Example 2 95 Example 3 98 Example 4 90 Comparative Example 1 71 Comparative Example 2 67 Comparative Example 3 78

[0135] As can be seen from Table 2, the conductivity of the mesoporous carbons in Examples 1 to 4 is better than that in Comparative Examples 1 to 3, and the conductivity of the mesoporous carbon in Example 1 reaches 104 S / cm.

[0136] From the comparison of the sample data of Example 1 and Comparative Example 1, it can be seen that Example 1 with nitrogen doping achieved by adding a nitrogen-containing curing agent has higher conductivity.

[0137] According to Table 2 and Figure 4 it can be known that from the comparison of the sample data of Example 1 and Comparative Example 3, it can be seen that the mesoporous carbon sample based on thermosetting phenolic resin has better conductivity than the thermoplastic sample. The mesoporous carbon prepared in Example 1 has two typical carbon characteristic peaks near 1350 cm -1 and 1590 cm -1 , which are the D peak representing the defect structure and the G peak representing the ordered structure respectively. According to the area ratio of the D peak and the G peak, ID / IG is calculated. The I D / I G of the sample in Example 1 is 1.19, while the I D / I G of the sample in Comparative Example 1 is 1.42, indicating that the sample in Example 1 has a higher degree of graphitization than Comparative Example 3.

[0138] According to Figure 5 it can be seen that the mesoporous carbon in Example 1 contains atomic functional groups such as C, S, N, and O, and has obvious C-N functional group characteristic peaks in the wavelength range of 800 - 900 cm -1 , while the sample in Comparative Example 1 does not have obvious C-O functional group characteristic peaks. Therefore, the nitrogen-containing curing agent realizes heteroatom doping.

[0139] Test Example 4

[0140] The working electrodes prepared in Example 1 and Comparative Examples 1 to 3 were characterized. The characterization method is as follows: High-purity N 4 was introduced into a 0.1 mol / L HCIO 2, purged for 30 min to remove dissolved oxygen. In a three - electrode system, the thin - film electrode is the working electrode, the saturated calomel electrode is the reference electrode, the Pt sheet is the counter electrode, and the electrolyte is N 2 saturated 0.1 mol / L HClO 4 solution. The catalyst was activated at a scanning rate of 100 mV / s until the area of the hydrogen desorption peak no longer increased to clean the catalyst surface. In the range of 0 - 1.2 V RHE (relative to the reversible hydrogen electrode potential), scanned 5 cycles at a speed of 50 mV / s, recorded the cyclic voltammogram at this time, and calculated the electrochemically active area; high - purity O 4 was introduced into the 0.1 mol / L HCIO 2 solution, purged for 30 min to make it oxidation - saturated. In a three - electrode system, the rotational speed of the ring electrode is 1500 r / min. In the scanning range of 0.2 - 1.2 V RHE , scanned forward at a speed of 10 mV / s, and recorded the current density at 0.9 V RHE at this time. The characterization results are shown in Table 3 below. The polarization curves of Example 1 and Comparative Example 1 are as Figure 6 shown, and the cyclic voltammograms of Example 1 and Comparative Example 3 are as Figure 7 shown.

[0141] Table 3:

[0142]

[0143] According to Table 3, Figure 6 and Figure 7 it can be seen that the platinum - based catalyst with mesoporous carbon as the carrier in Example 1 has the optimal catalytic performance in the application of hydrogen fuel cells. The electrochemically active area is 182.6 m 2 / g, and the current density at 0.9 V RHE is 4.42 mA / cm 2 . Compared with Comparative Examples 1 - 3, the mesoporous carbon in Example 1 has better electrical conductivity and thermal stability, and thus has better catalytic performance.

[0144] In the description of this specification, the descriptions with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms may be directed to different embodiments or examples. Moreover, the specific features, structures, materials, or characteristics described may be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0145] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of such features. In the description of the present invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise specifically defined.

[0146] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A method for preparing phenolic resin-based nitrogen-doped mesoporous carbon, characterized in that: The following steps are involved: (a) adding a template to a phenolic resin solution and stirring to obtain a gel-like mixture; (b) adding a curing agent to the gel-like mixture and curing the mixture to obtain a cured sample; (c) laying the solidified sample powder on the carbon cloth electrode and subjecting it to high temperature thermal shock carbonization and activation treatment to obtain preliminary mesoporous carbon; (d) washing and drying the preliminary mesoporous carbon sample powder to obtain mesoporous carbon.

2. The preparation method according to claim 1, characterized in that The mass ratio of the phenolic resin to the template is (1-4):

1.

3. The preparation method according to claim 1, characterized in that: The particle size of the template agent is 5 to 10 nm.

4. The preparation method according to claim 1, characterized in that: The template includes one or more of potassium hydroxide, potassium chloride, potassium carbonate, sodium hydroxide, sodium carbonate, and sodium chloride.

5. The preparation method according to claim 1, characterized in that: The added amount of the curing agent is 0.5% to 15% of the mass of the phenolic resin.

6. The preparation method according to claim 1, characterized in that: The curing agent includes one or more of ammonium chloride, ammonium sulfate, hexamethylenetetramine, triethylamine, dicyandiamide, urea, and amino resin.

7. The preparation method according to claim 1, characterized in that: The power of the high temperature thermal shock carbonization and activation treatment is 40-48 kW and the time is 10-30 seconds.

8. The preparation method according to claim 1, characterized in that: The solution preparation process of the phenolic resin comprises the following steps: Add 15% to 20% of the mass of phenol in ammonia water to the molten phenol while stirring; In a 65°C water bath, add 37% formaldehyde solution at a concentration of 50% to 60% of the mass of phenol and react for 1 to 2 hours; In a 70°C water bath, add 37% formaldehyde solution at a concentration of 50% to 60% of the mass of phenol and react for 1 to 3 hours; The mixture is cooled to 45-55°C and a solvent is added to obtain a phenolic resin solution.

9. A phenolic resin-based nitrogen-doped mesoporous carbon, characterized in that: The invention is prepared by the preparation method according to any one of claims 1 to 8.

10. Use of the mesoporous carbon prepared by the preparation method according to any one of claims 1 to 8 or the mesoporous carbon according to claim 9 in a catalyst carrier.

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