Mesoporous carbon material and preparation method thereof, catalyst and fuel cell

Abstract

The invention discloses a mesoporous carbon material and a preparation method thereof, a catalyst and a fuel cell, and relates to the technical field of fuel cells, the mesoporous carbon material satisfies the following conditions: 1.2 < 1000 * V / SSA < 2.0; 1.8 < ID / IG < 2.2; wherein V is the volume of mesopores of the mesoporous carbon material, and the pore diameter of the mesopores is 2-50 nm; sSA is the specific surface area of the mesoporous carbon material; iD is D peak intensity of the mesoporous carbon material measured by Raman spectrum; iG is the G peak intensity of the mesoporous carbon material measured by a Raman spectrum. The mesoporous carbon material prepared by the invention has relatively high electrochemical activity and excellent structural stability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fuel cells, in particular to a mesoporous carbon material, a preparation method thereof, a catalyst and a fuel cell. BACKGROUND

[0002] As a device for directly converting the chemical energy of fuel (such as H2) and oxidant (such as O2) into electrical energy, the core bottleneck of a fuel cell lies in the slow kinetics of the cathode ORR (Oxidation-Reduction Reaction), which needs to rely on high-cost platinum (Pt) based catalysts, and the traditional carbon black carrier easily causes Pt particles to agglomerate and deactivate and the mass transfer efficiency is insufficient. The mesoporous carbon material can significantly improve the utilization rate of noble metals by realizing high dispersion of Pt nanoparticles on the basis of high specific surface area, and can simultaneously optimize the diffusion of reaction products (O2) and the discharge efficiency of products (H2O), relieve the electrode flooding problem, and provide an efficient electron conduction path. Although high specific surface area can provide abundant active sites, the material is prone to oxidation, which leads to the collapse of the pore structure and thus affects the durability of the material, so it is urgent to provide a mesoporous carbon carrier with high activity and high durability. SUMMARY

[0003] The main purpose of the present application is to provide a mesoporous carbon material, a preparation method thereof and a fuel cell, which aims to solve the problem that the existing mesoporous carbon material cannot have high activity and high durability.

[0004] To achieve the above-mentioned purpose, the mesoporous carbon material provided by the present application satisfies: 1.2 < 1000 x V / SSA < 2.0; 1.8 < ID / IG < 2.2; wherein V is the mesopore volume of the mesoporous carbon material, and the pore size of the mesopore is 2-50 nm; SSA is the specific surface area of the mesoporous carbon material; ID is the D peak intensity of the mesoporous carbon material measured by Raman spectroscopy; IG is the G peak intensity of the mesoporous carbon material measured by Raman spectroscopy.

[0005] Preferably, the mesoporous carbon material further satisfies at least one of the following conditions: (1) the mesopore volume V is: 1 cm 3 / g≤V≤2cm 3 / g; (2) the total pore volume of the mesoporous carbon material is V 总 , and the proportion of the mesopore volume V is: 60% < V / V 总 < 92%; (3) the average pore size D of the mesopore is: 4.5 ≤ D ≤ 11 nm; (4) the specific surface area SSA of the mesoporous carbon material is: 750 m 2 / g≤SSA≤1050 m 2 / g.

[0006] The application further provides a preparation method of the mesoporous carbon material. mixing the pore-forming template and the carbon source solution to obtain a composite precursor; carburizing the composite precursor to obtain a carburized precursor; etching the carburized precursor to remove the pore-forming template and obtain an etched precursor; graphitizing the etched precursor to obtain the mesoporous carbon material.

[0007] Preferably, the preparation method of the mesoporous carbon material further comprises at least one of the following conditions: (1) the particle size of the pore-forming template is 5-20 nm; (2) the mass ratio of the carbon source to the pore-forming template is 0.5:1-3:1; (3) the carburizing temperature of the carburizing treatment is 600-1000℃; (4) the graphitizing temperature of the graphitizing treatment is 1500-2200℃.

[0008] Preferably, the preparation method of the mesoporous carbon material further comprises at least one of the following conditions: (1) the pore-forming template comprises one or more of ordered mesoporous silica, water-soluble inorganic salt and soluble metal oxide; (2) the mass fraction ratio of carbon element to hydrogen element in the carbon source is greater than 6.5; (3) the carbon source comprises one or more of sugar, thermosetting resin and polymer; (4) the atmosphere of the carburizing treatment is a nitrogen atmosphere or an inert gas atmosphere.

[0009] Preferably, the sugar comprises one or more of sucrose, glucose and starch; the thermosetting resin comprises one or more of phenolic resin and furfuryl alcohol resin; the polymer comprises one or more of polyacrylonitrile, polystyrene and polyvinyl chloride.

[0010] Preferably, the composite precursor is prepared by one of the following methods: (1) after mixing the pore-forming template and the carbon source solution, ultrasonic treatment is performed to form a mixed slurry; the mixed slurry is rapidly frozen in a liquid nitrogen environment to obtain the composite precursor; (2) Add a thickener to the carbon source solution and stir evenly to obtain a carbon source slurry; mix the pore-forming template with the carbon source slurry and then ultrasonically stir to obtain the composite precursor.

[0011] Preferably, the etching process includes: etching the carbonized precursor using an acid solution; The acid solution includes one or more of hydrochloric acid, nitric acid, and dilute sulfuric acid.

[0012] This application also proposes a catalyst, comprising the mesoporous carbon material proposed in this application, or the mesoporous carbon material prepared by the method proposed in this application.

[0013] The present invention also proposes a fuel cell including a membrane electrode assembly, the membrane electrode assembly including a proton exchange membrane, a catalyst layer and a gas diffusion layer, the catalyst layer including the catalyst provided in this application.

[0014] This invention discovers that when mesoporous carbon materials satisfy 1.2 < 1000 × V / SSA < 2.0 and 1 < ID / IG < 1.3, a three-dimensional interconnected network structure dominated by mesopores (2~50 nm) can be constructed, balancing the contradiction between "high specific surface area" and "large pore volume", thus enabling mesoporous carbon materials to have both high activity and high durability. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0016] Figure 1 The battery cyclic volt-ampere curve corresponding to Embodiment 1 provided by the present invention.

[0017] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0019] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0020] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0021] Mesoporous carbon materials (with pore sizes of 2-50 nm) achieve highly dispersed loading of Pt nanoparticles due to their high specific surface area, significantly improving the utilization rate of precious metals. Their interconnected pore structure simultaneously optimizes reactant (O2) diffusion and product (H2O) removal efficiency, alleviating electrode flooding problems and providing efficient electron conduction pathways. As a catalyst support, this material can overcome the activity and mass transfer limitations of traditional carbon black, improving battery power density and lifespan. Therefore, the high performance exhibited by fuel cells depends to a certain extent on the high specific surface area of ​​the support. A higher specific surface area provides abundant anchoring sites for active sites, achieving high dispersion of platinum (Pt) nanoparticles, thereby increasing the electrochemical active surface area. However, high specific surface area materials are more prone to oxidation, leading to pore structure collapse, thus potentially affecting material durability. High-durability mesoporous carbon materials typically require graphitization treatment at high temperatures, but high graphitization reduces the specific surface area. Therefore, mesoporous carbon materials for fuel cells face a challenging trade-off between performance and durability.

[0022] Based on this, the present invention proposes a method for preparing mesoporous carbon materials, which is a hard pore-forming template method, comprising: S1. Precursor impregnation: A pore-forming template and a carbon source solution are provided. The pore-forming template and the carbon source solution are mixed uniformly to obtain a pore-forming template-carbon source composite precursor.

[0023] S2. Heat treatment: The pore-forming template-carbon source composite precursor is dried and carbonized.

[0024] S3. Removal of the pore-forming template: The heat-treated pore-forming template-carbon source composite precursor is etched.

[0025] The mass ratio of carbon source to pore-forming template is 0.5:1 to 3:1. For example, the mass ratio can be 0.5:1, 1:1, 1.5:1, 2:1, 2.5:1, or 3:1. If the mass ratio of carbon source to pore-forming template is less than 0.5:1, the amount of carbon source is insufficient. After removing the pore-forming template, the carbon skeleton of the mesoporous carbon material is incomplete or even broken, resulting in a lower-than-expected specific surface area and pore volume, thus affecting its mechanical strength. If the ratio of carbon source to pore-forming template is greater than 3:1, the amount of carbon source is excessive. Excessive carbon source will form a thick, unstructured carbon shell on the surface of the pore-forming template-carbon source composite precursor. The carbon shell is usually disordered and will block the pore openings, thereby reducing the specific surface area and mass transfer efficiency of the mesoporous carbon material. Furthermore, its disorder will increase the ID / IG ratio of the mesoporous carbon material, reducing the durability of the material. Preferably, the mass ratio of carbon source to pore-forming template is 1:1 to 2:1. This ratio ensures that the prepared mesoporous carbon material forms a complete, hollow, and interconnected mesoporous carbon network, which is the key to achieving a high V / SSA ratio (i.e., large pore size and high pore volume) and high structural regularity in mesoporous materials.

[0026] Furthermore, the pore-forming template comprises one or more of ordered mesoporous silica, water-soluble inorganic salts, and soluble metal oxides. For example, the pore-forming template is a soluble metal oxide. The soluble metal oxide is a nanoparticle with an average particle size of 5-20 nm; for example, the average particle size of the soluble metal oxide nanoparticles is 5 nm, 6 nm, 7 nm, 8 nm, 10 nm, 15 nm, 20 nm, etc. The BET specific surface area of ​​the soluble metal oxide nanoparticles is greater than 80 m². 2 / g. Preferably, the BET specific surface area of ​​the soluble metal oxide nanoparticles is 150~400 m². 2 / g. For example, the BET specific surface area of ​​soluble metal oxide nanoparticles is 150 m². 2 / g、200 m 2 / g、250 m 2 / g、300 m 2 / g、350 m 2 / g or 400 m 2 / g etc. In some embodiments, the soluble metal oxide pore-forming template includes one or more of magnesium oxide nanoparticles, zinc oxide, and manganese dioxide.

[0027] It should be noted that by limiting the average particle size of the pore-forming template, not only the pore-forming template itself is limited, but also the pore structure of the prepared mesoporous carbon material is directly related. If the average particle size of the pore-forming template is too small, it is easy to cause the pore structure of the prepared mesoporous carbon material to be too small, which is not conducive to mass transfer; if the average particle size of the pore-forming template is too large, the pore structure of the prepared mesoporous carbon material will be too large, resulting in a decrease in specific surface area. The various pore-forming templates and their preferred size ranges listed above, although there are differences between specific values, their selection principles are the same: according to the 1000×V / SSA value and ID / IG value required for the target mesoporous carbon material. That is, the preparation of the mesoporous carbon material in the present invention can be achieved by using the pore-forming templates of different materials listed above.

[0028] In one embodiment, the mass fraction ratio of carbon element to hydrogen element (C / H) in the carbon source is greater than 6.5, preferably greater than 7.5. The mass fraction of carbon element before carbonization is greater than 60%, preferably greater than 65%. The carbon source includes one or more of sugar, thermosetting resin, and polymer. A high C / H ratio usually means that the molecule of the carbon source has an aromatic structure such as a benzene ring or a highly cross-linked network structure (such as phenolic resin). Such carbon sources are more likely to form a graphitic sp² carbon structure through polycondensation reaction during carbonization, rather than generating a large amount of amorphous aliphatic carbon. Furthermore, it directly promotes the preparation of the mesoporous carbon material to obtain an ideal lower ID / IG ratio from the source, making the mesoporous carbon material have a higher degree of graphitization and stability.

[0029] Specifically, in some embodiments, the sugar includes one or more of sucrose (C / H≈7.2), glucose, and starch. The thermosetting resin includes one or more of phenolic resin (C / H>9) and furfuryl alcohol resin. The polymer includes one or more of polyacrylonitrile (PAN), polystyrene (PS), and polyvinyl chloride (PVC).

[0030] By controlling the average particle size of the pore-forming template, the chemical composition of the carbon source, and the ratio between the two, a mesoporous carbon material satisfying 1.4 < 1000×V / SSA < 2.0 and 1.0 < ID / IG < 1.3 is finally obtained. By optimizing the V / SSA ratio, while ensuring high activity, a more stable and corrosion-resistant carbon structure is obtained. At the same time, by precisely controlling the ID / IG ratio of the mesoporous carbon material between 1.0 and 1.3, a "best defect state" is formed: enough defects are retained to provide a high specific surface area and active sites, and a stable basic skeleton is formed through moderate graphitization, thereby achieving both high activity and high durability of the mesoporous carbon material.

[0031] In some embodiments, the precursor impregnation specifically includes the steps: S21. Provide a pore-forming template and a carbon source, mix the pore-forming template with the carbon source solution, and form a slurry through ultrasonic treatment; S22. After freezing the slurry, freeze-dry it to obtain the pore-forming template-carbon source composite precursor.

[0032] A uniformly dispersed slurry is formed by mixing a pore-forming template with a carbon source solution and then ultrasonically treating the mixture. This slurry is then freeze-dried to instantly solidify the solvent, fixing the dispersion of the template and carbon source. Finally, freeze-drying is performed under vacuum and low temperature conditions to sublimate the solvent, yielding a dried pore-forming template-carbon source composite precursor. This ultrasonic-freeze-freeze-drying technique effectively avoids the particle stacking and pore structure collapse caused by solvent surface tension during conventional drying processes. This facilitates more precise replication of the template's nanostructure, resulting in mesoporous carbon materials with more uniform pore structure, higher specific surface area, and higher pore volume.

[0033] Traditional impregnation methods (even with ultrasonic and vacuum assistance) have inherent limitations in the final drying stage, such as pore-forming template stacking: during liquid evaporation, the pore-forming template particles move as the liquid level drops, eventually accumulating tightly together under capillary forces. This results in large agglomerates of the pore-forming template in the final carbon material, leading to an uneven replicated structure. Another issue is pore collapse: solvents (especially water) have high surface tension. When the solvent evaporates from the nanopores, the resulting enormous capillary forces pull on the fragile, uncarbonized carbon source framework, causing some micropores and small mesopores to collapse or shrink. This reduces the final specific surface area and pore volume, making it impossible to accurately replicate the original structure of the pore-forming template.

[0034] Therefore, compared with the conventional impregnation and drying method, the processing method in this invention can significantly improve the uniformity of the structure of mesoporous carbon materials, making it easier to control and obtain the optimal V / SSA ratio.

[0035] In some embodiments, the ultrasonic treatment power is 200-500 W, and the time is 10-60 min. For example, the ultrasonic treatment power is 200 W, 300 W, 400 W, or 500 W, and the time is 10 min, 20 min, 30 min, 40 min, 50 min, or 60 min, etc. Preferably, the ultrasonic treatment power is 400 W, and the time is 30 min.

[0036] In some embodiments, the freeze-drying temperature is -80 to -40°C, the vacuum degree is less than 10 Pa, and the time is 48 to 96 hours. For example, the freeze-drying temperature is -80°C, -70°C, -60°C, -50°C, or -40°C, and the time is 48 hours, 60 hours, 72 hours, 84 hours, or 96 hours. Preferably, the freeze-drying temperature is -60°C and the time is 72 hours.

[0037] In some embodiments, the carbonization atmosphere is a nitrogen atmosphere or an inert gas atmosphere, for example, the carbonization atmosphere includes one or more of nitrogen, helium, neon, and argon. The carbonization temperature is 600~1000℃. For example, the carbonization temperature is 600℃, 700℃, 800℃, 900℃, or 1000℃, etc.

[0038] In some embodiments, the etching process includes etching the heat-treated pore-forming template-carbon source composite precursor with an acid solution. The acid solution includes one or more of hydrochloric acid, nitric acid, and dilute sulfuric acid.

[0039] In some embodiments, the preparation method of mesoporous carbon materials further includes the step: S4, graphitizing the etched pore-forming template-carbon source composite precursor at 1500~2200℃ in an inert atmosphere. For example, the graphitization temperature is 1500℃, 1600℃, 1700℃, 1800℃, 1900℃, 2000℃, 2100℃, 2200℃, etc. The inert atmosphere includes one or more of helium, neon, and argon. Through graphitization, the conductivity and structural stability of the mesoporous carbon material can be further optimized.

[0040] This invention also proposes a mesoporous carbon material prepared using the method described above. Further, the specific surface area and mesopore volume of the mesoporous carbon material satisfy the following: 1.4 cm³ / (g·m² / g) < 1000 × V / SSA < 2.0 cm³ / (g·m² / g). The graphitization degree of the mesoporous carbon material satisfies: 1 < ID / IG < 1.3. Wherein, V is the mesopore volume, SSA is the specific surface area, and ID is the D peak (~1330 cm⁻¹) determined by Raman spectroscopy. - ¹) Intensity, IG is the G peak (~1590 cm⁻¹) measured by Raman spectroscopy. - ¹) Strength.

[0041] The ratio of specific surface area (SSA) to mesoporous pore volume (V) reflects the "accessibility" of the pore structure of mesoporous carbon materials. A value in this range indicates that the material has a moderate pore size and good pore connectivity, which is conducive to rapid ion transport and maintaining structural integrity.

[0042] Specifically, the V / SSA ratio controls the pore structure and determines three core properties of mesoporous carbon materials: dispersibility, mass transfer efficiency, and durability. When the V / SSA is too small, the mesoporous carbon material is dominated by micropores and small mesopores, with a large specific surface area but small pore volume. Although the high specific surface area is beneficial for the high dispersion of platinum (Pt) nanoparticles, forming fine particles and exposing more active sites, the narrow pores make it difficult for reactants (oxygen, hydrogen) and products (water) to diffuse rapidly. Especially at high current densities, water is difficult to drain, which can flood the pores and cause a sharp decline in performance. When the V / SSA is too large, the material is dominated by macropores. The wide pores are conducive to mass transport with almost no mass transfer resistance, but the low specific surface area cannot provide enough anchoring points, resulting in low Pt particle dispersion. Pt particles are prone to sintering and agglomeration into large particles, and the number of active sites is sharply reduced. Macroporous structures usually come from more graphitized carbon, which has higher chemical stability and stronger corrosion resistance. However, because the activity is too low, the overall "performance-lifetime" comprehensive score is not high.

[0043] The degree of graphitization was determined by Raman spectroscopy, with its D peak (~1330 cm⁻¹) - ¹) Intensity (ID) and G peak (~1590 cm⁻¹) - ¹) The intensity (IG) ratio, i.e., ID / IG, is strictly controlled within the range of greater than 1.0 and less than 1.3. This ratio indicates that the mesoporous carbon material has a moderate degree of graphitization: it contains enough graphite microcrystals to ensure excellent conductivity and intrinsic stability, while retaining an appropriate amount of structural defects to provide abundant electrochemical active sites.

[0044] When both the V / SSA and ID / IG ratios are at suitable values, i.e., 1.4 < 1000 × V / SSA < 2.0 and 1 < ID / IG < 1.3, the mesoporous carbon material successfully constructs an ideal pore network dominated by moderately sized mesopores and interconnected in three dimensions. This unique structure cleverly balances the contradiction between "high specific surface area" and "large pore volume," thereby synergistically optimizing the various properties of the mesoporous carbon material. High dispersibility and high activity. The sufficiently large specific surface area (SSA) provides abundant and uniform anchoring sites for platinum (Pt) nanoparticles, ensuring that the catalyst particles can be stably loaded in a high-density, small-size form, thereby exposing a large number of catalytic active sites and laying the foundation for high electrochemical activity.

[0045] High mass transfer efficiency. Sufficiently large mesopore volume (V) and suitable pore size form an unobstructed "nanoscale three-dimensional transportation network." This structure ensures that reactants (such as oxygen and protons) can rapidly diffuse to every deep active site, while products (water) can also be quickly discharged. This greatly reduces mass transfer resistance at high current densities, effectively avoiding performance degradation caused by flooding, and enabling the fuel cell to output high and stable power.

[0046] Excellent durability. The optimized pore structure and its moderate degree of graphitization (1.0 < ID / IG < 1.3) complement each other. The mesoporous pore walls are thicker and more robust than the micropores. At the same time, the moderately graphitized microcrystals are like "steel bars" embedded in the carbon skeleton, significantly enhancing the intrinsic electrochemical inertness of the material, enabling it to effectively resist carbon corrosion (C + 2H2O → CO2 + 4H + + 4e - ).) under high potential conditions such as the start and stop of fuel cells. The stability of the carrier structure means that it can firmly fix the Pt particles, preventing catalyst agglomeration, loss, and deactivation caused by the corrosion and collapse of the carrier.

[0047] The present invention also provides a fuel cell, comprising a membrane electrode, the membrane electrode comprising a proton exchange membrane, a catalytic layer, and a gas diffusion layer, the catalytic layer comprising the mesoporous carbon material as described above and a platinum-based catalyst supported on the mesoporous carbon material.

[0048] The following is further illustrated by specific examples.

[0049] Example 1 This example prepares a mesoporous carbon material, comprising the following steps: S101. Pretreatment of the pore-forming template: Magnesium oxide (MgO) nanopowder with an average primary particle size of 8 nm is placed in a vacuum drying oven and dried at 120 °C for 4 hours to thoroughly remove the surface-adsorbed moisture.

[0050] S102. Preparation of the carbon source solution: Weigh a certain amount of phenolic resin and dissolve it in deionized water to prepare a solution with a concentration of 25 wt%. Subsequently, add concentrated sulfuric acid accounting for 5% of the mass of the phenolic resin as a catalyst, and magnetically stir until completely dissolved to obtain a clear solution.

[0051] S103. Ultrasound-assisted impregnation and mixing: Mix the pretreated MgO pore-forming template and the phenolic resin solution at a mass ratio of 1:1.2 (MgO: phenolic resin). Place the mixture in an ultrasonic cell disruptor and ultrasonically treat it at a power of 400 W for 30 minutes under an ice-water bath condition to form a uniform suspension.

[0052] S104. Rapid freezing to fix the structure: Pour the ultrasonically treated suspension quickly into a pre-cooled copper mold and immediately immerse it in liquid nitrogen (-196 °C) to rapidly freeze the sample within seconds to form a solid ice block.

[0053] S105. Removing solvent by freeze drying: The frozen sample is quickly transferred to a freeze dryer and freeze-dried at -60℃ and a vacuum of 5 Pa for 48 h to allow the ice crystals to sublimate directly, resulting in a fluffy MgO / phenolic resin composite precursor powder that maintains a uniform dispersion.

[0054] S106. Pre-carbonization treatment: The precursor powder obtained by freeze-drying is placed in a tube furnace and heated from room temperature to 300°C at a rate of 2°C / min under nitrogen atmosphere protection (gas flow rate: 100 mL / min), and held at this temperature for 1 hour. This step causes the phenolic resin to undergo preliminary cross-linking and carbonization, forming a stable intermediate and fixing the macroscopic structure.

[0055] S107. High-temperature carbonization treatment: After pre-carbonization, the temperature is further increased to 900℃ at a rate of 5℃ / min under a nitrogen atmosphere, and carbonized at this temperature for 2 hours. This process completely converts organic carbon into an amorphous carbon skeleton, forming a MgO / carbon composite material.

[0056] S108. Removal of the pore-forming template: The carbonized product from S7 was naturally cooled to room temperature. Then, it was immersed in a 2M dilute hydrochloric acid solution and magnetically stirred for 24 h to completely dissolve the MgO pore-forming template. After the reaction, it was repeatedly washed with deionized water until the filtrate was neutral, and then dried at 110℃ for 12 h to obtain the preliminary mesoporous carbon material.

[0057] S109, Graphitization Treatment: The mesoporous carbon material after removing the pore-forming template is placed in a high-temperature graphitization furnace and heated to 1450℃ (second temperature, graphitization temperature) at a heating rate of 8℃ / min under the protection of a high-purity argon atmosphere, and graphitized at this temperature for 1.5 h. This step is the core of precisely controlling the degree of graphitization (ID / IG ratio) and chemical stability of the carbon material.

[0058] S110, Post-processing: After graphitization, the powder is cooled to room temperature in the furnace to obtain the final black mesoporous carbon powder. It is then gently ground in an agate mortar and passed through a 400-mesh sieve to obtain the mesoporous carbon material.

[0059] Example 2 The difference between Example 2 and Example 1 is: In step S101, the average primary particle size of the magnesium oxide (MgO) nanoparticles is 10 nm.

[0060] In step S102, phenolic resin is replaced with saccharin resin.

[0061] In step S107, the temperature for high-temperature carbonization is 800°C.

[0062] Everything else is the same as in Example 1.

[0063] Example 3 The difference between Example 3 and Example 1 is: In step S101, the average primary particle size of the magnesium oxide (MgO) nanoparticles is 7 nm.

[0064] In step S102, phenolic resin is replaced with sucrose.

[0065] In step S109, the graphitization temperature is 1800℃.

[0066] Everything else is the same as in Example 1.

[0067] Example 4 The difference between Example 4 and Example 1 is: Step S103: Add thickener: Add sodium carboxymethyl cellulose to the phenolic resin catalytic solution. The amount of sodium carboxymethyl cellulose added is 5% of the mass of the phenolic resin. Place the mixture with sodium carboxymethyl cellulose on a magnetic stirrer and stir for 30 minutes at a constant temperature of 30°C to obtain a uniform, viscous carbon source slurry without particle agglomeration.

[0068] Step S104: Add the pore-forming template: Add the pretreated MgO pore-forming template and carbon source slurry at a mass ratio of 1:1.2 (MgO: phenolic resin) into the jacketed ultrasonic reaction vessel; circulate ice-water bath water into the jacket to maintain the system temperature at 5°C, then turn on the ultrasonic cell disruptor and ultrasonically treat it at 400W power for 30 minutes to obtain a viscous suspension with uniformly dispersed MgO particles.

[0069] Step S105, Drying to obtain powder: Transfer the ultrasonically dispersed viscous suspension to a tray with a polytetrafluoroethylene liner, and control the thickness of the spread to 5 mm. Then place the tray in a vacuum drying oven and set the drying parameters as follows: temperature 80℃, vacuum degree 5 Pa, and drying time 10 hours. After drying, take out the sample and grind it gently with an agate mortar to obtain a fluffy MgO / sucrose composite precursor powder with MgO particles in a uniformly dispersed state. Everything else is the same as in Example 1.

[0070] Example 5 The difference between Example 5 and Example 1 is: In step S102, phenolic resin is replaced with sucrose.

[0071] In step S103, the MgO pore-forming template and the carbon source slurry are mixed at a mass ratio of 0.5:1.

[0072] Everything else is the same as in Example 1.

[0073] Example 6 The difference between Example 6 and Example 1 is: In step S102, phenolic resin is replaced with phenolic resin.

[0074] In step S103, the MgO pore-forming template and the carbon source slurry are mixed at a mass ratio of 3:1.

[0075] Everything else is the same as in Example 1.

[0076] Example 7 The difference between Example 7 and Example 1 is: In step S103, the MgO pore-forming template and the carbon source slurry are mixed at a mass ratio of 1.3:1.

[0077] In step S109, the graphitization temperature is 2200℃.

[0078] Everything else is the same as in Example 1.

[0079] Example 8 The difference between Example 8 and Example 1 is: In step S101, magnesium oxide (MgO) nanopowder is replaced with silicon dioxide (SiO2) nanopowder. In step S108, hydrochloric acid is replaced with hydrofluoric acid.

[0080] In step S109, the graphitization temperature is 1500℃.

[0081] Everything else is the same as in Example 1.

[0082] Example 9 The difference between Example 9 and Example 1 is: In step S102, phenolic resin is replaced with sucrose.

[0083] In step S107, the temperature for high-temperature carbonization is 700°C.

[0084] In step S109, the graphitization temperature is 2100℃.

[0085] Everything else is the same as in Example 1.

[0086] Example 10 The difference between Example 10 and Example 1 is: In step S101, the average primary particle size of the magnesium oxide (MgO) nanoparticles is 20 nm.

[0087] In step S102, phenolic resin is replaced with sucrose.

[0088] In step S107, the temperature for high-temperature carbonization is 800°C.

[0089] In step S109, the graphitization temperature is 1600℃.

[0090] Everything else is the same as in Example 1.

[0091] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is as follows: In step S107, the temperature for high-temperature carbonization is 500°C.

[0092] Everything else is the same as in Example 1.

[0093] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is as follows: In step S107, the high-temperature carbonization treatment temperature is 1250°C.

[0094] Everything else is the same as in Example 1.

[0095] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is as follows: In step S109, the graphitization temperature is 2400℃.

[0096] Everything else is the same as in Example 1.

[0097] Comparative Example 4 The difference between Comparative Example 4 and Example 1 is as follows: In step S109, the graphitization temperature is 1300℃.

[0098] Everything else is the same as in Example 1.

[0099] Comparative Example 5 The difference between Comparative Example 5 and Example 1 is as follows: In step S105, conventional impregnation drying is used instead of rapid freeze drying.

[0100] Everything else is the same as in Example 1.

[0101] Comparative Example 6 The difference between Comparative Example 6 and Example 1 is as follows: In step S101, the average primary particle size of the magnesium oxide (MgO) nanoparticles is 5 nm.

[0102] In step S105, conventional impregnation drying is used instead of rapid freeze drying.

[0103] In step S107, the temperature for high-temperature carbonization is 800°C.

[0104] In step S109, the graphitization temperature is 1500℃.

[0105] Everything else is the same as in Example 1.

[0106] Methods for testing and calculating the physical properties of mesoporous carbon materials Mesopore size: Tested according to GB / T 21650.3-2011.

[0107] Mesopore volume: After testing according to GB / T 21650.3-2011, the pore volume corresponding to the adsorption isotherm is calculated using the BJH method, i.e., the total pore volume (V). 总 Then select the cumulative pore size corresponding to D≈50nm, denoted as V50, and select the cumulative pore size corresponding to D≈2nm, denoted as V2. The absolute difference between V50 and V2 is the mesopore volume.

[0108] Mesopore volume percentage: The ratio of mesopore volume to total pore volume is the mesopore volume percentage, i.e., V% = |V50 - V2| / V 总 .

[0109] Specific surface area (SSA): Tested according to GB / T 19587-2017.

[0110] ID and IG: Raman spectrometers equipped with 532nm lasers were used to scan 1000–2000 cm⁻¹ at 5–10mW power. - ¹Wavenumber range, acquire spectra and perform baseline correction; read 1350cm - Peak D at 1580cm - The maximum signal intensity at peak G is used to obtain ID and IG.

[0111] Fuel cells were prepared using the mesoporous carbon materials prepared in Examples 1-10 and Comparative Examples 1-6, respectively, with the following steps: (1) Catalyst preparation method: Chloroplatinic acid was dissolved in ethylene glycol and added dropwise to the carbon materials prepared in the above examples and comparative examples under vigorous stirring. After drying, the carbon materials were heated and reduced in a mixed gas of hydrogen and argon with a volume ratio of 1:9 at 300℃ for 90 min. Then, the carbon materials prepared in the above examples and comparative examples were dispersed in water, and H2PtCl6 and formic acid were added. The mixture was stirred for 5 h, filtered, washed, and dried to obtain the platinum-carbon catalyst. The platinum loading of the platinum-carbon catalyst was tested by adding 10 g of catalyst sample to aqua regia for digestion, filtering (if there is residue), and making up to a final volume.

[0112] (2) Half-cell construction method: Weigh 200 mg of catalyst and add 5% Nafion solution, deionized water and isopropanol in sequence. Sonicate the mixture to disperse it into a homogeneous slurry. The catalyst loading on the electrode surface is 50 μg / cm³. 2 ~200 μg / cm 2 A suitable amount of the well-dispersed slurry was evenly added dropwise to the smooth and clean surface of a disc electrode in two separate applications. After drying, it served as the working electrode. The working electrode was placed in an electrolytic cell to form a three-electrode system. The reference electrode was a reversible hydrogen electrode (RHE), the counter electrode was a large-area Pt sheet, and the electrolyte was a saturated 0.1 mol / L HClO4 solution.

[0113] (3) Battery performance testing: Cyclic voltammetry was performed using a potentiostat. Cyclic voltammetry curves were tested: the catalyst was first activated at a scan rate of 20 mV / s until the hydrogen desorption peak area no longer increased. Then, the catalyst was scanned for 5 cycles at a rate of 20 mV / s, with a potential scan range of 0.05 V to 1.1 V vs RHE. The stabilized cyclic voltammetry curve was selected, and the hydrogen desorption peak (0.05 V to 0.4 V vs RHE) was integrated to obtain the area S. The electrochemically active area (ECSA) was calculated using the formula.

[0114] Calculate ECSA according to the formula: ECSA (m 2 / g-Pt)=(100×S) / (C×v×M) Where S is the integrated area of ​​the hydrogen desorption / adsorption peak (A*V), and C is the charge constant of hydrogen adsorbed on the smooth Pt surface (0.21 mC / cm²). 2 v is the scanning speed (mV / s), and M is the mass of Pt on the working electrode (g).

[0115] (4) Test method for half-cell durability: Under air conditions of 65°C, 0.9 V is maintained for 3 s and 0.65 V is maintained for 2 s as a square wave cycle. The ECSA retention rate is tested after 50,000 cycles.

[0116] The prepared fuel cell was characterized and its performance was tested. The results are as follows: Figure 1 As shown in Tables 1 and 2.

[0117] Table 1 Characterization Tests of Mesoporous Carbon Materials

[0118] Table 2 Fuel Cell Performance Tests

[0119] According to Tables 1 and 2, by comparing Examples 1-10 and Comparative Examples 1-4, it can be seen that when 1.2 < 1000 × V / SSA < 2.0 and 1.8 < ID / IG < 2.2, the electrochemical specific surface area (ECSA) of the fuel cell reaches 73 m². 2 With a surface area of ​​ / g-Pt or higher, the ECSA retention rate after 50,000 cycles is above 71%, achieving a balance between high activity and high durability. However, when either 1000×V / SSA or ID / IG is outside the range required by this invention, the electrochemical specific surface area (ECSA) of the fuel cell (corresponding to electrochemical activity) and the ECSA retention rate after 50,000 cycles (corresponding to durability) are both low.

[0120] As shown in Comparative Example 5, if the pore-forming template and carbon source solution are not kept evenly dispersed in the carbon source solution by rapid freezing after the pore-forming template is mixed evenly, the pore-forming template particles will settle and agglomerate, resulting in a smaller number and volume of mesopores in the carbon material and an uneven distribution of pore structure, which in turn leads to lower electrochemical activity and durability.

[0121] As shown in Comparative Example 6, although the carbon material satisfies the conditions of 1.2 < 1000 × V / SSA < 2.0 and 1.8 < ID / IG < 2.2, its mesoporous pore volume ratio is relatively small, indicating that there are many macropores in the carbon material, resulting in a lower specific surface area and consequently lower activity and durability.

[0122] Comparing Examples 1-7 and Examples 8-9, it can be seen that, based on the conditions that the mesoporous carbon material satisfies 1.2 < 1000 × V / SSA < 2.0 and 1.8 < ID / IG < 2.2, when the mesoporous pore volume V is further controlled to 1 cm³, 3 / g≤V≤2cm 3 / g, or control the specific surface area SSA at 750 m². 2 / g≤SSA≤1050m 2 At a concentration of / g, activity and durability can be further improved, resulting in an electrochemical specific surface area (ECSA) of 83 m² for the fuel cell. 2 With a g-Pt of above 50,000 cycles, the ECSA retention rate remained above 81%, further achieving a balance between high activity and high durability.

[0123] Comparing Examples 1 and 4, it can be seen that although adding a thickener can also keep the pore-forming template particles in a uniformly dispersed state, compared with the rapid freezing method, the electrochemical specific surface area (ECSA) and the ECSA retention rate after 50,000 cycles are reduced. This may be because the addition of the thickener also introduces certain impurities, which affects the pore structure of the mesoporous carbon material, thereby reducing its activity and durability.

[0124] The above description is merely an exemplary embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention specification and drawings under the technical concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A mesoporous carbon material, characterized in that, The mesoporous carbon material satisfies: 1.2 < 1000 × V / SSA < 2.0; 1.8 < ID / IG < 2.2; Wherein, V is the mesoporous pore volume of the mesoporous carbon material, and the pore diameter of the mesoporous material is 2~50 nm; SSA is the specific surface area of ​​the mesoporous carbon material; ID is the intensity of the D peak of the mesoporous carbon material as determined by Raman spectroscopy; IG is the intensity of the G peak of the mesoporous carbon material as determined by Raman spectroscopy.

2. The mesoporous carbon material according to claim 1, characterized in that, The mesoporous carbon material also satisfies at least one of the following conditions: (1) The mesoporous pore volume V is: 1 cm 3 / g≤V≤2cm 3 / g; (2) The total pore volume of the mesoporous carbon material is V 总 The proportion of the mesoporous pore volume V is: 60% < V / V 总 <92%; (3) The average pore size D of the mesopores is: 4.5 ≤ D ≤ 11 nm; (4) The specific surface area (SSA) of the mesoporous carbon material is 750 m². 2 / g≤SSA≤1050m 2 / g.

3. A method for preparing a mesoporous carbon material as described in claim 1 or 2, characterized in that, include: The pore-forming template and the carbon source solution were uniformly mixed to obtain the composite precursor; The composite precursor is subjected to carbonization treatment to obtain a carbonized precursor; The carbonized precursor is etched to remove the hole-forming template, resulting in an etched precursor. The etched precursor is graphitized to obtain a mesoporous carbon material.

4. The method for preparing mesoporous carbon materials according to claim 3, characterized in that, It also includes at least one of the following conditions: (1) The particle size of the pore-forming template is 5~20nm; (2) The mass ratio of the carbon source to the pore-forming template is 0.5:1 to 3:1; (3) The carbonization temperature of the carbonization treatment is 600~1000℃; (4) The graphitization temperature of the graphitization treatment is 1500~2200℃.

5. The method for preparing mesoporous carbon materials according to claim 4, characterized in that, It also includes at least one of the following conditions: (1) The pore-forming template comprises one or more of ordered mesoporous silica, water-soluble inorganic salts, and soluble metal oxides; (2) The mass fraction ratio of carbon to hydrogen in the carbon source is greater than 6.5; (3) The carbon source includes one or more of sugars, thermosetting resins, and polymers; (4) The atmosphere for the carbonization process is a nitrogen atmosphere or an inert gas atmosphere.

6. The method for preparing mesoporous carbon material as described in claim 5, characterized in that, The sugar includes one or more of sucrose, glucose, and starch; The thermosetting resin includes one or more of phenolic resin and furfuryl alcohol resin; The polymer includes one or more of polyacrylonitrile, polystyrene, and polyvinyl chloride.

7. The method for preparing mesoporous carbon materials as described in claim 3, characterized in that, The composite precursor is prepared by one of the following methods: (1) The pore-forming template is mixed with the carbon source solution and then ultrasonically treated to form a mixed slurry; the mixed slurry is placed in a liquid nitrogen environment for rapid freezing to obtain the composite precursor; (2) Add a thickener to the carbon source solution and stir evenly to obtain a carbon source slurry; mix the pore-forming template with the carbon source slurry and then ultrasonically stir to obtain the composite precursor.

8. The method for preparing mesoporous carbon materials as described in claim 3, characterized in that, The etching process includes: etching the carbonized precursor using an acid solution; The acid solution includes one or more of hydrochloric acid, nitric acid, and dilute sulfuric acid.

9. A catalyst, characterized in that, It includes the mesoporous carbon material as described in claim 1 or 2, or the mesoporous carbon material prepared by the preparation method as described in any one of claims 3 to 8.

10. A fuel cell, characterized in that, It includes a membrane electrode, which comprises a proton exchange membrane, a catalyst layer, and a gas diffusion layer, wherein the catalyst layer comprises the catalyst of claim 9.

Images