Porous carbon material, preparation method and application thereof

Abstract

The invention provides a porous carbon material as well as a preparation method and application thereof, and belongs to the technical field of carbon materials, the preparation method of the porous carbon material comprises a pore-forming step, and the pore-forming step specifically comprises the following steps: mixing copper-containing carbon intermediate powder obtained by pyrolyzing a Cu-BDC precursor with aqua regia according to a certain liquid-solid ratio to form a pre-pore-forming mixture; after the pre-pore-forming mixture reacts for a period of time, a final reactant mixture is formed, copper particles in the copper-containing carbon intermediate are selectively removed by utilizing the strong oxidizing property of aqua regia, so that holes left by the copper particles are expanded, adjacent micropores are broken through to form mesopores, in the process, the copper particles are removed, the micropores are amplified in situ, and the mesopores are formed. A hierarchical pore channel structure rich in mesopores (2-50nm) is successfully constructed in a carbon skeleton, and the structure has high specific surface area and excellent ion conductivity; and carrying out suction filtration treatment on the final reactant mixture, collecting a filter cake, and washing the filter cake to finally obtain the porous carbon material.

Description

Technical Field

[0001] This invention relates to the field of carbon materials technology, and in particular to a porous carbon material, its preparation method, and its application. Background Technology

[0002] Capacitive deionization (CDI) is an emerging water desalination technology based on the electrochemical double-layer theory. When saline solution flows through a channel between a pair of electrodes to which an external electric field is applied, ions in the solution (such as Na+) are deionized. + Cl - Electrostatics (electrostatic adsorption, etc.) are adsorbed onto the electrode surface and stored in the electric double layer at the electrode / solution interface, thereby achieving water desalination. Compared with traditional desalination technologies such as reverse osmosis and distillation, CDI has advantages such as low energy consumption, low operating pressure, environmental friendliness, and no secondary pollution, showing broad application prospects in brackish water desalination and industrial wastewater reuse.

[0003] In CDI systems, electrode materials are the core components that determine their desalination performance. An ideal CDI electrode material should possess high specific surface area, suitable pore structure, good conductivity, excellent electrochemical stability, and low cost.

[0004] Currently, porous carbon materials are the main electrode materials for CDI, among which activated carbon (AC) is widely studied due to its abundant raw material sources and low cost. However, the specific surface area of ​​commercial activated carbon is usually not optimal, and its pore structure is complex, mainly consisting of micropores (pore size <2nm). During the CDI process, the double layer in the micropores overlaps severely, leading to a decrease in the effective specific surface area utilization rate. At the same time, the narrow pores hinder the rapid transport of ions, causing concentration polarization, thus limiting the desalination capacity of the material, which is generally below 20mg / g, failing to meet the requirements for efficient desalination. Summary of the Invention

[0005] In view of this, and to address the above shortcomings, it is necessary to propose a porous carbon material, its preparation method, and its application to solve the technical problems of commercial activated carbon being mainly microporous (pore size <2nm). During the CDI process, the double electric layer in the micropores is severely overlapped, leading to a reduction in the effective specific surface area utilization rate. At the same time, the narrow pores hinder the rapid transport of ions, causing concentration polarization, thereby limiting the desalination capacity of the material, which is generally below 20mg / g, and cannot meet the requirements of efficient desalination.

[0006] The technical solution adopted by this invention to solve its technical problem is:

[0007] In a first aspect, the present invention provides a method for preparing a porous carbon material, including a pore-forming step, wherein the pore-forming step specifically comprises:

[0008] The copper-containing carbon intermediate powder obtained by pyrolysis of Cu-BDC precursor is mixed with aqua regia at a predetermined liquid-solid ratio to form a pre-porous mixture. After the pre-porous mixture reacts for a predetermined time, a final reactant mixture is formed. The copper particles in the copper-containing carbon intermediate powder are removed by the aqua regia, and the pores left by the copper particles are enlarged. The adjacent micropores are opened to form mesopores, and a hierarchical pore structure rich in mesopores is constructed in the carbon skeleton.

[0009] The final reactant mixture is subjected to vacuum filtration, the filter cake is collected and washed, and finally the porous carbon material is obtained.

[0010] Preferably, in the pore-forming step, the liquid-to-solid ratio of the copper-carbon intermediate powder to aqua regia is 5-12.5 mg / mL.

[0011] Preferably, in the pore-forming step, "waiting for the pre-pore-forming mixture to react for a predetermined time" specifically means: stirring with a magnetic stirrer at a speed of 200-500 rpm, maintaining the stirring temperature at 30-80℃, and continuing to stir for 8-16 hours to form a final reactant mixture.

[0012] Preferably, the preparation method of the porous carbon material further includes a pyrolysis step, which specifically involves: placing the Cu-BDC precursor into a crucible, placing it in a high-temperature tube furnace with a protective atmosphere, heating it from room temperature to the target temperature at a heating rate of 2-3℃ / min, and then naturally cooling it to room temperature to obtain the copper-containing carbon intermediate powder.

[0013] Preferably, in the pyrolysis step, the target temperature is 500-1100℃.

[0014] Preferably, the method for preparing the porous carbon material further includes a precursor synthesis step, wherein the precursor synthesis step specifically comprises:

[0015] Cu(NO3)2·3H2O and terephthalic acid were weighed according to a molar ratio and dissolved in a solvent to form a pre-reaction mixture;

[0016] The pre-reaction mixture was subjected to a hydrothermal reaction. After the hydrothermal reaction was completed, it was naturally cooled to room temperature, washed with an organic solvent, and the solid was collected by centrifugation.

[0017] The collected solids were dried under vacuum to obtain the Cu-BDC precursor.

[0018] Preferably, in the precursor synthesis step, the molar ratio of Cu(NO3)2·3H2O to terephthalic acid is 1:1-2.

[0019] Preferably, in the precursor synthesis step, the hydrothermal reaction is carried out at a temperature of 140-180℃ for a time of 6-12 hours.

[0020] In a second aspect, the present invention provides a porous carbon material, which is prepared according to the method for preparing porous carbon materials described in the first aspect.

[0021] Thirdly, the present invention provides the application of the porous carbon material described in the second aspect as an electrode for capacitive deionization.

[0022] Compared with the prior art, the advantages of this invention are as follows: This invention sacrifices a portion of the carbon skeleton to obtain richer defects and more optimized pores. Specifically, aqua regia is used for etching to create pores, and its strong oxidizing properties selectively remove copper particles from the copper-containing carbon intermediate, thereby enlarging the pores left by the copper particles and opening up adjacent micropores to form mesopores. This process not only removes copper particles but also expands micropores in situ, successfully constructing a hierarchical pore structure rich in mesopores (2-50 nm) in the carbon skeleton. This structure has both high specific surface area and excellent ion conductivity: the abundant mesopores provide a fast transport channel for ions, effectively suppressing concentration polarization; while the retained micropores and newly formed mesopores jointly contribute a large number of ion adsorption sites. The two work synergistically to significantly improve the effective specific surface area and ion adsorption kinetics performance of the material. Attached Figure Description

[0023] Figure 1 This is a scanning electron microscope image of the Cu-BDC precursor obtained in Example 1.

[0024] Figure 2 This is a scanning electron microscope image of the copper-carbon intermediate obtained after pyrolysis of the Cu-BDC precursor in Example 1 at the target temperature (900℃).

[0025] Figure 3 The BDCE obtained in Example 1 900 Scanning electron microscope image.

[0026] Figure 4 For BDCE 900 The graph shows the change in solution conductivity over time at different operating voltages for a CDI electrode in a NaCl solution with an initial conductivity of 1000 μS / cm.

[0027] Figure 5 The BDCE obtained in Examples 1 to 4 900 BDCE 700 BDCE 1100 BDCE 500 XRD comparison chart.

[0028] Figure 6 The BDCE obtained in Examples 1 to 4900 BDCE 700 BDCE 1100 BDCE 500 A comparison diagram of aperture distribution.

[0029] Figure 7 The BDCE obtained in Examples 1 to 4 900 BDCE 700 BDCE 1100 BDCE 500 Comparison of the desalination capabilities of CDI electrodes in NaCl solutions with an initial conductivity of 1000 μS / cm under different operating voltages. Detailed Implementation

[0030] To further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, and not for limiting the scope of the claims of the present invention.

[0031] In a first aspect, the present invention provides a method for preparing a porous carbon material, including a pore-forming step, wherein the pore-forming step specifically comprises:

[0032] The copper-containing carbon intermediate powder obtained by pyrolysis of Cu-BDC precursor is mixed with aqua regia at a predetermined liquid-solid ratio to form a pre-porous mixture. After the pre-porous mixture reacts for a predetermined time, a final reactant mixture is formed. The copper particles in the copper-containing carbon intermediate powder are removed by the aqua regia, and the pores left by the copper particles are enlarged. The adjacent micropores are opened to form mesopores, and a hierarchical pore structure rich in mesopores is constructed in the carbon skeleton.

[0033] The final reactant mixture is subjected to vacuum filtration, the filter cake is collected and washed, and finally the porous carbon material is obtained.

[0034] Compared with the prior art, the advantages of this invention are as follows: This invention sacrifices a portion of the carbon skeleton to obtain richer defects and more optimized pores. Specifically, aqua regia is used for etching to create pores, and its strong oxidizing properties selectively remove copper particles from the copper-containing carbon intermediate, thereby enlarging the pores left by the copper particles and opening up adjacent micropores to form mesopores. This process not only removes copper particles but also expands micropores in situ, successfully constructing a hierarchical pore structure rich in mesopores (2-50 nm) in the carbon skeleton. This structure has both high specific surface area and excellent ion conductivity: the abundant mesopores provide a fast transport channel for ions, effectively suppressing concentration polarization; while the retained micropores and newly formed mesopores jointly contribute a large number of ion adsorption sites. The two work synergistically to significantly improve the effective specific surface area and ion adsorption kinetics performance of the material.

[0035] Furthermore, in the pore-forming step, the liquid-to-solid ratio of the copper-carbon intermediate powder to aqua regia is 5-12.5 mg / mL. For example, the copper-carbon intermediate powder is 150-250 mg and the aqua regia is 20-30 mL. If the liquid-to-solid ratio is too low (<5 mg / mL), the pre-pore-forming mixture will become too viscous, and the aqua regia will not be able to fully wet and contact each copper-carbon intermediate powder particle. In particular, deeply coated copper particles will be difficult to reach, resulting in copper particle residue and uneven etching. If the liquid-to-solid ratio is too high (>12.5 mg / mL), although the etching reaction can be guaranteed to be thorough, it will increase the cost of the aqua regia reagent and the subsequent waste liquid treatment load.

[0036] Furthermore, in the pore-forming step, the "pre-determined reaction time of the pre-pore-forming mixture" specifically refers to: stirring with a magnetic stirrer at a speed of 200-500 rpm, maintaining the stirring temperature at 30-80℃, and continuing stirring for 8-16 hours to form a final reactant mixture. Specifically, under magnetic stirring, aqua regia first reacts violently with the copper component exposed on the surface of the copper-carbon intermediate powder, generating a soluble complex that dissolves in the aqua regia, thereby forming initial cavities in the copper-carbon intermediate powder particles. Subsequently, the etching process proceeds towards the copper-carbon intermediate powder particles. The intermediate powder particles develop in depth: On the one hand, aqua regia, with its strong oxidizing properties, continuously corrodes the inner wall of the cavity, causing the pores to expand continuously; on the other hand, for two adjacent micropores separated by thin carbon walls, aqua regia oxidizes and etches away the separating carbon atoms, thereby connecting the two adjacent micropores into a larger mesopore. In addition, since a large number of copper particles are deeply encapsulated inside the carbon matrix, aqua regia, through the above two aspects of simultaneous etching, gradually opens up and exposes the copper particles encapsulated inside the carbon matrix, ultimately achieving the complete removal of copper particles and the comprehensive construction of the mesoporous structure.

[0037] Furthermore, the preparation method of the porous carbon material also includes a pyrolysis step, which specifically involves: placing the Cu-BDC precursor in a crucible, placing it in a high-temperature tube furnace with a protective atmosphere (inert atmosphere), heating it from room temperature to the target temperature at a heating rate of 2-3℃ / min, and then naturally cooling it to room temperature to obtain the copper-containing carbon intermediate powder. Specifically, during the pyrolysis of the Cu-BDC precursor, a slow heating rate (2-3℃ / min) is initially used to allow the organic ligands to decompose and release gradually and orderly. Small molecule gases are used to minimize the collapse of the carbon skeleton due to sudden and violent gas production, laying the structural foundation for the basic porous framework inherited from the MOF precursor. After reaching the target temperature, it is naturally cooled to room temperature, ensuring that heat is fully and evenly transferred to the center of the material to achieve complete pyrolysis, promoting the structural rearrangement and stabilization of the carbon skeleton. Finally, the MOF organic ligand is successfully transformed into a robust porous carbon matrix, which effectively inherits the framework characteristics of the precursor. At the same time, metallic copper species are reduced in situ to nanoparticles and uniformly dispersed in the carbon skeleton, together forming a copper-containing carbon intermediate powder.

[0038] Furthermore, in the pyrolysis step, the target temperature is 500-1100℃, preferably 900℃.

[0039] Furthermore, the preparation method of the porous carbon material also includes a precursor synthesis step, which specifically includes:

[0040] Cu(NO3)2·3H2O and terephthalic acid were weighed in a molar ratio and dissolved in a solvent to form a pre-reaction mixture, wherein the solvent was a mixed solution of N,N-dimethylformamide (DMF) and ethanol.

[0041] The pre-reaction mixture is subjected to a hydrothermal reaction. After the hydrothermal reaction is completed, it is naturally cooled to room temperature, washed with an organic solvent, and the solid is collected by centrifugation. The organic solvent is anhydrous ethanol.

[0042] The collected solid was dried under vacuum conditions. Specifically, the collected solid was transferred to a vacuum drying oven at 60-80°C and dried for 11-13 hours to finally obtain the Cu-BDC precursor.

[0043] Furthermore, in the precursor synthesis step, the molar ratio of Cu(NO3)2·3H2O to terephthalic acid is 1:1-2, ensuring that each Cu 2+ All of them have sufficient ligands (terephthalic acid) to react with them, thereby forming the Cu-BDC precursor with complete structure and high thermal stability.

[0044] Furthermore, in the precursor synthesis step, the hydrothermal reaction is carried out at a temperature of 140-180℃ for 6-12 hours. Compared to the room temperature reaction, the hydrothermal reaction temperature of 140-180℃ is [Cu] 2+ The coordination reaction with the organic ligand (terephthalic acid) provides significant energy, effectively overcoming the reaction energy barrier and ensuring extremely high reaction conversion rate, thereby generating the target product with high purity and minimizing the residue of unreacted raw materials or intermediates.

[0045] In a second aspect, the present invention provides a porous carbon material, which is prepared according to the method for preparing porous carbon materials described in the first aspect.

[0046] Thirdly, the present invention provides the application of the porous carbon material described in the second aspect as an electrode for capacitive deionization.

[0047] The following embodiments of the method of the present invention further illustrate the technical solution and technical effects of the present invention. It should be noted that the following experimental examples are only for further explanation of the present invention and do not limit the technical solution of the present invention.

[0048] Example 1: First, 0.242 g of Cu(NO3)2·3H2O and 0.166 g of terephthalic acid (PTA) were weighed and placed in a 65 mL mixed solvent consisting of 40 mL of N,N-dimethylformamide (DMF) and 25 mL of ethanol. Then, the mixture was magnetically stirred at 600 rpm at room temperature for 20 min until all solid particles were completely dissolved, forming a pre-reaction mixture. The pre-reaction mixture was transferred to a 100 mL polytetrafluoroethylene liner and incubated at 150 °C. After hydrothermal reaction for 6 hours, and after the hydrothermal reaction is completed and naturally cooled to room temperature, 20-30 mL of the turbid liquid is measured from the polytetrafluoroethylene liner and washed with an equal volume (20-30 mL) of anhydrous ethanol. Then, the solid is separated by centrifugation at 8000 rpm for 5 minutes and the supernatant is discarded. The washing and centrifugation process is repeated three times. Finally, the obtained solid precipitate is transferred to a vacuum drying oven at 70°C and dried for 12 hours (overnight) to obtain the Cu-BDC precursor.

[0049] Weigh 300 mg of the Cu-BDC precursor, place the weighed Cu-BDC precursor into a crucible, place it in a high-temperature tube furnace protected by argon gas, and heat it from room temperature to the target temperature (900℃) at a heating rate of 2℃ / min. Then, let it cool naturally to room temperature and take it out to obtain the copper-carbon intermediate powder.

[0050] Weigh 200 mg of the copper-containing carbon intermediate powder and transfer it to a beaker. Then, add 25 mL of aqua regia to the beaker to form a pre-porous mixture. Stir the pre-porous mixture using a magnetic stirrer at 300 rpm, maintaining the stirring temperature at 60°C, and continue stirring for 12 hours to form a final reactant mixture. Filter the final reactant mixture, collect the filter cake, and wash it to obtain the porous carbon material, labeled as BDCE. 900 .

[0051] like Figure 1 The image shown is a scanning electron microscope (SEM) image of the Cu-BDC precursor synthesized in Example 1. From... Figure 1 The two-dimensional layered cubic structure with a smooth surface and sharp edges can be clearly observed. Its morphology is regular and uniform, which is highly consistent with the typical crystal structure characteristics of Cu-BDC (copper terephthalate) metal-organic framework. The microscopic morphology confirms the successful synthesis of the target precursor.

[0052] like Figure 2 The image shown is a scanning electron microscope (SEM) image of the copper-carbon intermediate obtained after pyrolysis of the Cu-BDC precursor at the target temperature (900℃). (Compared to...) Figure 1 As can be seen from the comparison, during the pyrolysis process, the organic components in the Cu-BDC precursor decompose, resulting in a significant decrease in its surface smoothness, making it rough and uneven. At the same time, a large number of nanoscale copper particles begin to precipitate on its surface. This roughened surface structure and the generation of copper nanoparticles greatly increase the specific surface area of ​​the material and provide more active sites.

[0053] like Figure 3 The image shows the final product BDCE after etching the aforementioned copper-carbon intermediate powder with aqua regia. 900 The scanning electron microscope image shows that BDCE can be observed. 900 The morphology underwent further evolution: its surface roughness intensified, and Figure 2 The visible copper particles are selectively removed due to the etching effect of aqua regia, leaving behind a more loose and porous skeletal structure.

[0054] like Figure 4 As shown, this is the aforementioned BDCE 900 As a CDI electrode in a NaCl solution with an initial conductivity of 1000 μS / cm, the change in solution conductivity over time under different operating voltages was investigated. The results show that the conductivity of the NaCl solution decreases rapidly after the applied voltage, which directly proves that BDCE... 900 The electrode's ability to effectively adsorb salt ions in the solution (i.e., capacitive desalination) was demonstrated. Furthermore, as the operating voltage increased from 0.8V to 1.2V, both the rate and the final magnitude of the decrease in the conductivity of the NaCl solution significantly increased.

[0055] Example 2: The difference from Example 1 is that in this example, the temperature was increased from room temperature to the target temperature (700°C) at a heating rate of 2°C / min. All other components and conditions were the same as in Example 1, resulting in a porous carbon material labeled BDCE. 700 .

[0056] Example 3: The difference from Example 1 is that in this example, the temperature was increased from room temperature to the target temperature (1100℃) at a heating rate of 2℃ / min. All other components and conditions were the same as in Example 1. The resulting porous carbon material was labeled BDCE. 1100 .

[0057] Example 4: The difference from Example 1 is that in this example, the temperature was increased from room temperature to the target temperature (500°C) at a heating rate of 2°C / min. All other components and conditions were the same as in Example 1. The resulting porous carbon material was labeled BDCE. 500 .

[0058] like Figure 5 As shown, the BDCE obtained in Examples 1 to 4 900 BDCE 700 BDCE 1100 BDCE 500 The XRD pattern shows only broadened diffuse peaks without any sharp crystal diffraction peaks, which confirms that etching with aqua regia can effectively remove copper particles or their oxide crystalline phases, ultimately yielding a framework structure dominated by amorphous carbon.

[0059] like Figure 6 As shown, the BDCE obtained in Examples 1 to 4 900 BDCE 700 BDCE 1100 BDCE 500 The pore size distribution comparison chart shows that all products exhibit a concentrated mesoporous distribution centered at 4 nm, among which BDCE 900 The peak intensity is highest at this characteristic pore size, indicating the abundance of mesopores and the largest mesopore volume. This optimized pore structure has a dual advantage: First, the 4 nm mesopore size is much larger than the kinetic diameter of hydrated salt ions, providing a smooth transport channel for rapid ion diffusion and thus improving adsorption kinetics; second, BDCE 900 It has the largest number of mesopores, which directly translates into a huge specific surface area and abundant ion adsorption sites, thus significantly enhancing its desalination capability as a CDI electrode.

[0060] like Figure 7 As shown, the BDCE obtained in Examples 1 to 4900 BDCE 700 BDCE 1100 BDCE 500 The graph compares the desalination capacity of the CDI electrode in a NaCl solution with an initial conductivity of 1000 μS / cm under different operating voltages. The results show that for all products, the desalination capacity increases significantly with increasing operating voltage. This aligns with the basic principle of capacitive deionization technology: a higher applied voltage generates a stronger electric field on the electrode surface, driving more salt ions to migrate to the electrode and be adsorbed into the electric double layer. Furthermore, the target temperature has a decisive influence on the final performance. Under all tested voltages, BDCE... 900 As CDI electrodes, they all exhibited the highest desalting capacity and the fastest adsorption kinetics, significantly outperforming products prepared at other target temperatures, including BDCE at higher target temperatures. 1100 This optimal performance is due to BDCE 900 The combined advantages demonstrated in previous characterizations include: the most developed mesoporous structure dominated by 4 nm (facilitating rapid ion transport), the largest specific surface area (providing abundant adsorption sites), and a well-conducting framework combining highly graphitized and amorphous states. These characteristics work synergistically to make it the superior CDI electrode material. The inventors of this invention have also discovered that the BDCE obtained in Examples 1 to 4... 900 BDCE 700 BDCE 1100 BDCE 500 When used as a CDI electrode, it has similar adsorption capacity for anions and cations, making it suitable for use as a high-performance symmetrical CDI electrode. However, the surface chemistry of many existing carbon materials (such as oxygen-containing functional groups) may be biased towards adsorbing a certain type of ion, leading to an unbalanced use of the electrode and reducing overall efficiency and stability.

[0061] The above-disclosed embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of the invention. Those skilled in the art will understand that implementing all or part of the above-described embodiments and making equivalent changes in accordance with the claims of the present invention are still within the scope of the invention.

Claims

1. A method for preparing porous carbon materials, characterized in that, The process includes a hole-making step, which specifically includes: The copper-containing carbon intermediate powder obtained by pyrolysis of Cu-BDC precursor is mixed with aqua regia at a predetermined liquid-solid ratio to form a pre-porous mixture. After the pre-porous mixture reacts for a predetermined time, a final reactant mixture is formed. The copper particles in the copper-containing carbon intermediate powder are removed by the aqua regia, and the pores left by the copper particles are enlarged. The adjacent micropores are opened to form mesopores, and a hierarchical pore structure rich in mesopores is constructed in the carbon skeleton. The final reactant mixture is subjected to vacuum filtration, the filter cake is collected and washed, and finally the porous carbon material is obtained.

2. The method for preparing porous carbon materials according to claim 1, characterized in that, In the pore-forming step, the liquid-to-solid ratio of the copper-containing carbon intermediate powder to aqua regia is 5-12.5 mg / mL.

3. The method for preparing porous carbon materials according to claim 2, characterized in that, In the pore-forming step, "waiting for the pre-pore-forming mixture to react for a predetermined time" specifically means: stirring with a magnetic stirrer at a speed of 200-500 rpm, maintaining the stirring temperature at 30-80℃, and continuing to stir for 8-16 hours to form the final reactant mixture.

4. The method for preparing porous carbon materials according to claim 1, characterized in that, The method for preparing the porous carbon material further includes a pyrolysis step, which specifically involves placing the Cu-BDC precursor into a crucible, placing it in a high-temperature tube furnace with a protective atmosphere, heating it from room temperature to the target temperature at a heating rate of 2-3℃ / min, and then naturally cooling it to room temperature to obtain the copper-containing carbon intermediate powder.

5. The method for preparing porous carbon materials according to claim 4, characterized in that, In the pyrolysis step, the target temperature is 500-1100℃.

6. The method for preparing porous carbon materials according to claim 1, characterized in that, The method for preparing the porous carbon material further includes a precursor synthesis step, which specifically includes: Cu(NO3)2·3H2O and terephthalic acid were weighed according to a molar ratio and dissolved in a solvent to form a pre-reaction mixture; The pre-reaction mixture was subjected to a hydrothermal reaction. After the hydrothermal reaction was completed, it was naturally cooled to room temperature, washed with an organic solvent, and the solid was collected by centrifugation. The collected solid was dried under vacuum to finally obtain the Cu-BDC precursor.

7. The method for preparing porous carbon materials according to claim 6, characterized in that, In the precursor synthesis step, the molar ratio of Cu(NO3)2·3H2O to terephthalic acid is 1:1-2.

8. The method for preparing porous carbon materials according to claim 6, characterized in that, In the precursor synthesis step, the hydrothermal reaction is carried out at a temperature of 140-180℃ for 6-12 hours.

9. A porous carbon material, characterized in that, The porous carbon material is prepared according to any one of claims 1-8.

10. The application of the porous carbon material as described in claim 9 as an electrode for capacitive deionization.

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