TEMPO-functionalized carbon support c-tempo particles, methods of making and using same

Abstract

The application discloses TEMPO functionalized carbon carrier C-TEMPO particles and a preparation method and application thereof; the C-TEMPO particles take acid-oxidized porous carbon as a substrate, covalently graft TEMPO functional groups through amide bonds after activation of carboxyl groups to form a carbon-based double-electric-layer structure; the C-TEMPO particles have high specific surface area, rich redox active sites and excellent structural stability, can be used as ICC-FCDI negative flow electrodes, realize double-electric-layer physical adsorption and TEMPO reversible Faraday reaction synergistic deamination in an independent closed cycle system, have high adsorption capacity and excellent cycle stability for ammonium ions, compared with traditional carbon materials, the C-TEMPO particles effectively solve problems of easy falling of active components, low deamination capacity and slow kinetics in a flow electrode system, and can be widely applied to the field of ammonia-nitrogen wastewater treatment.

Description

Technical Field

[0001] This invention relates to a TEMPO-functionalized carbon support C-TEMPO particle, as well as a method for preparing the particle and its application. Background Technology

[0002] ICC-FCDI technology, as a green and efficient ammonia removal technology for water treatment, has been widely researched and applied in water purification and industrial wastewater ion removal due to its advantages such as low energy consumption, simple operation, no secondary pollution, and recyclable electrodes. ICC-FCDI adopts an independent closed-loop circulating flow electrode mode, which can achieve continuous and stable ammonia removal. As the core of the system, the electrode material's ion adsorption capacity, charge transport efficiency, and structural stability directly determine the overall ammonia removal performance and long-term use value.

[0003] Currently, conventional carbon-based electrode materials mainly include activated carbon and porous carbon, which rely on their high specific surface area to achieve physical adsorption of the double electric layer. However, these materials lack redox active sites, have weak Faraday pseudocapacitance contributions, and limited ion adsorption capacity. Conventional surface modification often adopts physical doping, simple adsorption, and other methods, resulting in weak interaction between functional groups and carbon supports. Under long-term fluid circulation and electrochemical action, these carbon supports are prone to detachment and failure, leading to rapid performance degradation.

[0004] TEMPO-type nitroxide radical functional groups possess reversible redox properties, providing abundant Faraday active sites and significantly enhancing charge storage and ion binding capabilities, making them ideal components for modifying carbon materials. Existing technologies have reported the immobilization of 4-amino-TEMPO with polyacrylic acid via amide bonds. However, polyacrylic acid is a non-conductive polymer, requiring further cross-linking and methylation to construct electron transport channels. This process is lengthy and offers limited improvement in conductivity, failing to meet the demands of rapid charge transfer in electrode materials. Other studies have explored depositing 4-amino-TEMPO onto porous carbon as a conductive substrate to construct a three-dimensional conductive network. However, in this approach, the bonding between 4-amino-TEMPO and the carbon substrate relies on physical deposition or weak interactions, lacking stable covalent bonds. Under the shear forces and electrochemical stresses of long-term cycling of the flow electrode, the active components are prone to dissolution or aggregation, leading to rapid capacity decay and deterioration of cycling stability. Furthermore, these methods often require the introduction of external binders such as MXene to assist film formation, increasing the complexity of the electrode composition and preparation costs. Therefore, developing covalently bonded C-TEMPO functionalized carbon materials with simple preparation processes, stable structures, and excellent electrochemical performance is of great practical significance for improving the ammonia nitrogen removal performance of ICC-FCDI. Summary of the Invention

[0005] Purpose of the invention: The purpose of this invention is to provide a TEMPO-functionalized carbon support C-TEMPO particle that has excellent structural stability, abundant redox active sites and good ion adsorption performance. It also provides a method for preparing the above-mentioned particle and its application in the field of ICC-FCDI. When used as a flow electrode in ICC-FCDI, it can achieve efficient ammonium ion removal and excellent cycling stability.

[0006] Technical solution: The TEMPO functionalized carbon carrier C-TEMPO particles of the present invention use acid-oxidized porous carbon as a substrate, and after activating the carboxyl groups, TEMPO functional groups are covalently grafted through amide bonds to form a carbon-based double electric layer structure.

[0007] The acid-oxidized porous carbon is a surface-rich carboxyl porous carbon substrate C-COOH modified with hydrochloric acid and concentrated nitric acid. The carboxyl group is covalently grafted with 4-amino-2,2,6,6-tetramethylpiperidinoxy (4-amino-TEMPO) to form a stable amide bond.

[0008] The preparation method of the above-mentioned TEMPO-functionalized carbon support C-TEMPO particles includes the following steps:

[0009] (1) Under a protective atmosphere, porous carbon is oxidized by acid, washed and dried to obtain acid-oxidized porous carbon C-COOH;

[0010] (2) Acid oxidation of porous carbon and carboxyl activator were mixed and activated in anhydrous DMF to prepare NHS-ester intermediate activation system;

[0011] (3) Add a DMF solution containing 4-amino-2,2,6,6-tetramethylpiperidinoxy (4-amino-TEMPO) to the intermediate activation system, heat and stir to complete the amidation reaction, wash and dry to obtain TEMPO-functionalized carbon support C-TEMPO particles.

[0012] In step (1), the acid oxidation is performed by first soaking porous carbon in 30-35% HCl solution for 40-50 min, washing it with water until neutral, drying it into carbon powder, adding 65-70% concentrated HNO3, and refluxing it at 90-110 ℃ under a nitrogen atmosphere for 4-6 h.

[0013] In step (2), the carboxyl activator is 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS), and the mass ratio of C-COOH, EDC and NHS is 1:1~1.5:1~1.5.

[0014] Specifically, step (2) involves dispersing C-COOH in anhydrous DMF using ultrasound, adding EDC and NHS, and stirring magnetically at 20-30°C for 1-3 hours to obtain the NHS-ester intermediate activation system.

[0015] In step (3), the stirring reaction temperature of the amidation reaction is 25~35 ℃ and the reaction time is 70~74 h.

[0016] The aforementioned TEMPO-functionalized carbon support C-TEMPO particles are used in ICC-FCDI electrode materials, which are the negative electrode flow electrode materials of ICC-FCDI.

[0017] The electrode material is prepared by the following method: C-TEMPO particles and conductive additives are mixed at a mass ratio of 8 to 9:1, preferably 9:1, and then dispersed in deionized water containing sodium chloride. The mixture is stirred evenly to obtain a stable flowing electrode slurry, which is suitable for independent closed-loop operation of ICC-FCDI.

[0018] Invention principle: The TEMPO-functionalized carbon carrier C-TEMPO particles of the present invention achieve synergistic optimization of physical adsorption and pseudocapacitive reaction through the surface functionalization modification design of the carbon carrier.

[0019] Specifically, carboxyl groups are introduced onto the carbon support surface via acid oxidation. After activation of the carboxyl groups with 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC) and N-hydroxysuccinimide (NHS), they are covalently grafted with 4-amino-TEMPO via amidation, achieving stable loading of TEMPO onto the carbon support surface. C-TEMPO particles, with porous carbon as the substrate, are covalently grafted with TEMPO functional groups. The high specific surface area of ​​porous carbon provides ample physical sites for ammonium ion adsorption, while the oxygen radical structure of the TEMPO functional groups constitutes abundant redox active sites, which can significantly enhance charge and ammonium ion storage capacity through efficient reversible Faraday reactions.

[0020] Simultaneously, acid oxidation introduces a large number of carboxyl groups onto the porous carbon surface, followed by EDC and NHS activation and amidation grafting, achieving a stable covalent connection between the TEMPO functional groups and the carbon support. Compared to physical blending modification, the binding strength of the active components is significantly improved. The strong covalent bonding of the amide bonds achieves a stable connection between the TEMPO functional groups and the carbon support, fully preserving the electrochemical performance of the active sites while endowing the material with excellent structural stability, avoiding the problem of functional group detachment during cycling. The good conductivity and porous structure of the porous carbon substrate establish efficient electron and ion transport channels, promoting charge transfer kinetics in the ICC-FCDI process. This innovative design, integrating the physical adsorption advantages of carbon-based materials, the pseudocapacitive advantages of TEMPO functional groups, and the stable covalent grafting structure, enables the C-TEMPO particle electrode to simultaneously achieve high ammonium ion removal rates and good cycle life in the ICC-FCDI process, providing a breakthrough solution for the development of next-generation high-efficiency water treatment electrode materials.

[0021] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: (1) The TEMPO functionalized carbon support C-TEMPO particles of the present invention achieve stable bonding between TEMPO functional groups and carbon support through amide bond covalent grafting. The C-TEMPO particles obtained by covalent grafting can achieve stable bonding between TEMPO functional groups and carbon support at 1 A·g -1 The specific capacity reaches 18.77 mAh·g -1 The carbon material prepared by the physical mixing method is 2.38 times that of the carbon material prepared by the physical mixing method, which proves the key role of the covalent grafting structure in maintaining the stability of the electrode material; (2) The carbon-based double electric layer physical adsorption and the reversible Faraday reaction of TEMPO form a synergistic effect, which significantly improves the charge storage capacity and ammonium ion capture capacity at 200 mg N·L -1 After constant pressure deammoniation in ammonium chloride solution for 1.5 h, the ammonium ion removal rate is as high as 98.75%, which is about 50% higher than that of physical mixing method, overcoming the defects of low adsorption capacity and weak selectivity of traditional single carbon-based flow electrode; (3) The flow electrode based on C-TEMPO particles is prepared by binder-free wet dispersion, the slurry has good fluidity, is suitable for ICC-FCDI peristaltic pump circulation operation, the preparation process is simple, the conditions are mild, and the controllability is strong, which has good practical promotion and application value. Attached Figure Description

[0022] Figure 1 XRD pattern of C-TEMPO particles prepared in Example 1;

[0023] Figure 2 The Raman spectrum of C-TEMPO particles obtained in Example 1;

[0024] Figure 3Cyclic voltammetry (CV) curves of C-TEMPO particles prepared in Example 1 as ICC-FCDI flow electrodes at different scan rates;

[0025] Figure 4 The charge-discharge curves (GCD) of C-TEMPO particles prepared in Example 1 as the ICC-FCDI flow electrode at different current densities are shown.

[0026] Figure 5 The specific capacity diagram of C-TEMPO particles prepared in Examples 1-4 as ICC-FCDI flow electrodes at different current densities;

[0027] Figure 6 Specific capacity diagrams of carbon materials prepared in Comparative Examples 1-4 as ICC-FCDI flow electrodes at different current densities;

[0028] Figure 7 C-TEMPO particles prepared in Example 1 were used as a flow electrode in an ICC-FCDI reactor at 200 mg NL. -1 Conductivity curve of ammonium chloride solution;

[0029] Figure 8 The materials prepared in Examples 1-4 and Comparative Examples 1-4 were used as ICC-FCDI flow electrodes in 200 mg NL. -1 Comparison chart of ammonium ion removal rates in ammonium chloride solution. Detailed Implementation

[0030] The technical solution of the present invention will be further described below with reference to the embodiments. The test materials used in the embodiments can all be purchased through conventional means.

[0031] Example 1

[0032] The method for preparing TEMPO-functionalized carbon support C-TEMPO particles according to the present invention is as follows:

[0033] (1) Preparation of C-COOH by acid oxidation modification: 3 g of porous carbon was soaked in 30% HCl solution for 40 min, washed with deionized water until neutral, and dried at 60 °C; 50 mL of 68% concentrated HNO3 was added to the dried carbon powder, and the mixture was refluxed at 100 °C under nitrogen atmosphere for 5 h. After the reaction was completed, the mixture was cooled, filtered, and washed repeatedly with deionized water until the pH of the filtrate was neutral. The filtrate was dried at 60 °C to obtain C-COOH.

[0034] (2) Carboxyl activation: Weigh 1.0954 g of the above C-COOH, sonicate for 5 min and disperse in 20 mL of anhydrous DMF, add 1.0954 g of EDC and 1.0954 g of NHS (C-COOH:EDC:NHS mass ratio of 1:1:1), and magnetically stir at 25 °C for 2 h to obtain the NHS-ester intermediate activation system;

[0035] (3) Amide-covalent grafting: Weigh 1.314 g of 4-amino-TEMPO, dissolve it in 30 mL of DMF and pour it into the above activation system. Stir continuously at 30 °C for 72 h. After the reaction is completed, the mixture is filtered and washed repeatedly with DMF until the filtrate is colorless. Dry it under vacuum at room temperature to obtain C-TEMPO particles.

[0036] Figure 1 X-ray diffraction patterns of original activated carbon (AC) and TEMPO-modified activated carbon (C-TEMPO) are shown. At 2θ≈23°, both AC and C-TEMPO exhibit significant broadened diffraction peaks, corresponding to the typical amorphous disordered stacking structure of carbon materials. A weaker, broader peak appears at 2θ≈43°, corresponding to the (100) crystal plane diffraction of graphite. The comparison shows that the diffraction peak positions of C-TEMPO are basically consistent with those of AC, indicating that TEMPO grafting modification did not destroy the main carbon skeleton structure of the activated carbon, and the material still maintains good amorphous carbon characteristics.

[0037] Figure 2 The figures show the Raman spectra of AC and C-TEMPO. As can be seen from the figures, both materials exhibit Raman spectroscopy at approximately 1340 cm⁻¹. -1 A D peak appears at approximately 1580 cm⁻¹. -1 The G peak appears at [location], which is a typical characteristic peak of carbon materials. Among them, the D peak represents the defects and disordered structure of carbon materials, while the G peak represents the ordered structure of the carbon framework with sp² hybridization. By comparing the peak intensity ratio [I / O]... D / I G It can be seen that: AC's I D / I G The carbon material has a relatively low I content and a relatively regular structure; after further TEMPO grafting modification, the I content of C-TEMPO increases. D / I G The continued increase indicates an increase in surface functional groups and defects, proving that TEMPO has been successfully grafted onto the surface of carbon materials.

[0038] Example 2

[0039] The method for preparing TEMPO-functionalized carbon carrier C-TEMPO particles of the present invention differs from that of Example 1 in that: in step (1), the acid oxidation reflux temperature is 90 °C and the reflux time is 6 h; in step (2), the activation temperature is 20 °C and the stirring time is 3 h; in step (3), the amidation reaction temperature is 25 °C and the reaction time is 74 h; the remaining conditions are the same as those of Example 1.

[0040] The specific preparation method is as follows: 3 g of porous carbon was soaked in 30% HCl solution for 40 min, washed with deionized water until neutral, and dried at 60 ℃; the dried carbon powder was mixed with 50 mL of 68% concentrated HNO3, refluxed at 90 ℃ under nitrogen atmosphere for 6 h, cooled and filtered, washed with water until neutral, and dried at 60 ℃ to obtain C-COOH; 1.0954 g of C-COOH was ultrasonically dispersed in 20 mL of anhydrous DMF for 5 min, 1.0954 g of EDC and 1.0954 g of NHS were added, and the mixture was magnetically stirred at 20 ℃ for 3 h, followed by the addition of 30 mL of DMF solution containing 1.314 g of 4-amino-TEMPO, and stirred continuously at 25 ℃ for 74 h. After the reaction was completed, the mixture was filtered and washed repeatedly with DMF until the filtrate was colorless, and then vacuum dried at room temperature to obtain C-TEMPO particle powder.

[0041] Example 3

[0042] The method for preparing TEMPO-functionalized carbon carrier C-TEMPO particles of the present invention differs from that of Example 1 in that: in step (2), the mass ratio of C-COOH, EDC and NHS is 1:1.2:1.2, that is, the amount of EDC and NHS added is increased to 1.3145 g respectively; in step (3), the amount of 4-amino-TEMPO added is 1.100 g; the other conditions are the same as those of Example 1.

[0043] The specific preparation method is as follows: 3 g of porous carbon was soaked in 30% HCl solution for 40 min, washed with deionized water until neutral, and dried at 60 ℃; the dried carbon powder was mixed with 50 mL of 68% concentrated HNO3, refluxed at 100 ℃ under nitrogen atmosphere for 5 h, cooled and filtered, washed with water until neutral, and dried at 60 ℃ to obtain C-COOH; 1.0954 g of C-COOH was ultrasonically dispersed in 20 mL of anhydrous DMF for 5 min, 1.3145 g of EDC and 1.3145 g of NHS (mass ratio 1:1.2:1.2) were added, and the mixture was magnetically stirred at 25 ℃ for 2 h, followed by the addition of 30 mL of DMF solution containing 1.100 g of 4-amino-TEMPO, and stirring was continued at 30 ℃ for 72 h. After the reaction was completed, the mixture was repeatedly filtered and washed with DMF until the filtrate was colorless, and then vacuum dried at room temperature to obtain C-TEMPO particle powder.

[0044] Example 4

[0045] The method for preparing TEMPO-functionalized carbon carrier C-TEMPO particles of the present invention differs from that of Example 1 in that the mass ratio of C-COOH, EDC and NHS in step (2) is 1:1.5:1.5, that is, the amount of EDC and NHS added is increased to 1.6431 g respectively; the other conditions are the same as those in Example 1.

[0046] The specific preparation method is as follows: 3 g of porous carbon was soaked in 30% HCl solution for 40 min, washed with deionized water until neutral, and dried at 60 ℃; the dried carbon powder was mixed with 50 mL of 68% concentrated HNO3, refluxed at 100 ℃ under nitrogen atmosphere for 5 h, cooled and filtered, washed with water until neutral, and dried at 60 ℃ to obtain C-COOH; 1.0954 g of C-COOH was ultrasonically dispersed in 20 mL of anhydrous DMF for 5 min, and 1.6431 g of EDC and 1.6431 g of NHS (mass ratio 1:1.5:1.5) were added, followed by 1.314 g of 4-amino-TEMPO in 30 mL of DMF solution, and stirred continuously at 30 ℃ for 72 h. After the reaction was completed, the mixture was filtered and washed repeatedly with DMF until the filtrate was colorless, and dried under vacuum at room temperature to obtain C-TEMPO particle powder.

[0047] Comparative Example 1

[0048] The preparation method of Comparative Example 1 is the same as that of Example 1, except that the EDC and NHS carboxyl activation steps are omitted, and C-COOH is directly mixed and stirred with a DMF solution containing 4-amino-TEMPO to obtain the modified carbon material.

[0049] Comparative Example 2

[0050] The preparation method of Comparative Example 2 is the same as that of Example 1, except that physical mixing is used instead of covalent grafting. Porous carbon and 4-amino-TEMPO are directly ground and mixed without acid oxidation and amidation reactions to obtain mixed carbon material.

[0051] Comparative Example 3

[0052] The preparation method of Comparative Example 3 is the same as that of Example 1, except that the heating temperature for amidation grafting is adjusted to 20 °C.

[0053] Comparative Example 4

[0054] The preparation method of Comparative Example 4 is the same as that of Example 1, except that the reaction time for amidation grafting is adjusted to 60 h.

[0055] The C-TEMPO prepared in Examples 1-4 and Comparative Examples 1-4 is used as an electrode material for ICC-FCDI. The specific application process is as follows:

[0056] The dried samples obtained in each embodiment and comparative example were thoroughly ground. The flow electrode slurry and the solution to be treated were prepared according to the experimental ratios. For the negative electrode flow electrode: 0.9483 g C-TEMPO powder, 0.1053 g conductive carbon black, and 20 mg sodium chloride were added to 20 mL of deionized water and stirred until evenly dispersed. For the positive electrode flow electrode: 0.9483 g activated carbon, 0.1053 g conductive carbon black, and 20 mg sodium chloride were added to 20 mL of deionized water and stirred until evenly dispersed. The intermediate reaction chamber solution was prepared with a volume of 40 mL and 200 mg NL... -1 Ammonium chloride solution was used as the simulated ammonia nitrogen wastewater to be treated. The prepared anolyte and cathode flow electrodes were connected to two independent closed-loop circulation pipelines of the ICC-FCDI device, ensuring the two electrode slurries flowed independently and did not mix; the intermediate chamber was connected to the ammonium chloride feed solution circulation loop. A peristaltic pump was started for full circulation, pre-emptively removing air bubbles and allowing the system to settle until the system conductivity baseline stabilized. A constant operating voltage was then applied to conduct the ICC-FCDI ammonia removal test.

[0057] pass Figures 3-4 It can be seen that the C-TEMPO particle electrode prepared in Example 1 has redox peaks, and at 1 A g -1 The specific capacity is 18.77 mAh g. -1 .

[0058] Figure 5 The specific capacity diagrams for C-TEMPO particles prepared in Examples 1-4 as ICC-FCDI flow electrodes are shown at different current densities. Figure 5 It can be seen that in 1 A·g -1At the given current density, the specific capacities of Examples 1-4 were 18.77, 16.84, 15.92, and 17.63 mAh·g, respectively. -1 All were significantly superior to the comparative examples. Example 1 showed the best performance, indicating that under the conditions of an acid oxidation temperature of 100 °C, a reflux time of 5 h, an activation and grafting temperature of 25–30 °C, and an EDC / NHS to carbon substrate mass ratio of 1:1:1, the degree of carboxylation on the carbon substrate surface and the amount of TEMPO grafting achieved optimal matching. Example 2, due to the reduced acid oxidation and activation temperatures, saw a decrease in carboxyl introduction efficiency and activation degree, resulting in a reduction in TEMPO grafting and a slight decrease in specific capacity. Although Examples 3 and 4 increased the EDC / NHS addition ratio, the specific capacity did not further increase; instead, it slightly decreased. This is because excessive activator may cause overactivation of carboxyl sites on the carbon substrate surface or side reactions affecting the effective grafting and charge transport efficiency of TEMPO.

[0059] Figure 6 The specific capacity diagrams of the carbon materials prepared in Comparative Examples 1-4 as ICC-FCDI flow electrodes are shown at different current densities. (1 A·g) -1 Below, the specific capacities of Comparative Examples 1-4 were 12.15, 7.89, 10.63, and 12.78 mAh·g, respectively. -1 The specific capacity was significantly lower than that of the embodiments. Specifically, Comparative Example 1 omitted the EDC / NHS activation step, resulting in ineffective grafting of TEMPO onto the carbon substrate surface, leading to a decrease in specific capacity of approximately 35% compared to Example 1. Comparative Example 2 employed a physical mixing method, where there was no chemical bond between TEMPO and the carbon substrate, and the active components were prone to physical separation during electrode slurry preparation and cycling, resulting in the lowest specific capacity (7.89 mAh·g). -1 The grafting rate of TEMPO was only 42% of that in Example 1; in Comparative Example 3, the amidation reaction temperature was lowered to 20 °C, resulting in insufficient grafting kinetics, a low TEMPO grafting rate, and a significant decrease in specific capacity; in Comparative Example 4, the amidation reaction time was shortened to 60 h, but the grafting reaction was not fully carried out, and the specific capacity was also lower than that of the examples. The above comparative results fully demonstrate that a suitable reaction temperature (25~35 °C) and a sufficient reaction time (70~74 h) are the key conditions for achieving efficient covalent grafting of TEMPO.

[0060] Figure 7 The C-TEMPO particle electrode material prepared in Example 1 was subjected to 200 mg NL -1 The conductivity curve of ammonium chloride solution shows that the removal rate of ammonium ions is 83.23% after 1 h and 98.75% after 1.5 h.

[0061] Figure 8The materials prepared in Examples 1-4 and Comparative Examples 1-4 were used as ICC-FCDI flow electrodes at 200 mg N·L⁻¹. -1 A comparison chart of ammonium ion removal rates in ammonium chloride solutions. Figure 8 It can be seen that after 1.5 h of reaction, Example 1 showed the highest ammonium ion removal rate, reaching 98.75%; Examples 2-4 showed removal rates of 84.12%, 89.54%, and 86.46%, respectively, all significantly better than Comparative Examples 1-4 (54.23%, 65.78%, 48.56%, and 57.79%). This trend is consistent with the specific capacity test results ( Figure 5 , Figure 6 The results showed a high degree of consistency, further verifying the crucial role of covalently grafted TEMPO functional groups in enhancing the charge storage capacity and ammonium ion capture capacity of carbon materials. Meanwhile, Comparative Example 3, due to its low reaction temperature, resulted in insufficient grafting, with a removal rate of only 48.56%, lower than all other examples. Comparative Example 4, due to its shortened reaction time, also exhibited incomplete grafting, resulting in a removal rate significantly inferior to all other examples. In summary, this invention, through optimizing acid oxidation conditions, activation, and grafting process parameters, achieved efficient and stable covalent grafting of TEMPO functional groups onto the surface of a carbon substrate. The resulting C-TEMPO particles possess both high specific capacity and excellent deammoniation performance.

Claims

1. A TEMPO-functionalized carbon support C-TEMPO particle, characterized in that, The C-TEMPO particles are based on acid-oxidized porous carbon. After activating the carboxyl groups, TEMPO functional groups are covalently grafted through amide bonds to form a carbon-based double-layer structure.

2. The TEMPO-functionalized carbon support C-TEMPO particles according to claim 1, characterized in that, The acid-oxidized porous carbon is a surface-rich carboxyl-modified porous carbon substrate C-COOH modified with hydrochloric acid and concentrated nitric acid.

3. A method for preparing TEMPO-functionalized carbon support C-TEMPO particles as described in claim 1, characterized in that, Includes the following steps: (1) Under a protective atmosphere, porous carbon is oxidized by acid, washed and dried to obtain acid-oxidized porous carbon C-COOH; (2) Acid oxidation of porous carbon and carboxyl activator were mixed and activated in anhydrous DMF to prepare NHS-ester intermediate activation system; (3) Add a DMF solution containing 4-amino-2,2,6,6-tetramethylpiperidinoxy 4-amino-TEMPO to the intermediate activation system, heat and stir to complete the amidation reaction, wash and dry to obtain TEMPO-functionalized carbon support C-TEMPO particles.

4. The preparation method according to claim 3, characterized in that, In step (1), the acid oxidation is performed by first soaking porous carbon in 30-35% HCl solution for 40-50 min, washing it with water until neutral, drying it into carbon powder, adding 65-70% concentrated HNO3, and refluxing it at 90-110 ℃ under a nitrogen atmosphere for 4-6 h.

5. The preparation method according to claim 3, characterized in that, In step (2), the carboxyl activator is 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride EDC and N-hydroxysuccinimide NHS, and the mass ratio of C-COOH, EDC and NHS is 1:1~1.5:1~1.

5.

6. The preparation method according to claim 5, characterized in that, Step (2) specifically involves dispersing C-COOH in anhydrous DMF using ultrasound, adding EDC and NHS, and stirring magnetically at 20-30 °C for 1-3 h to obtain the NHS-ester intermediate activation system.

7. The preparation method according to claim 3, characterized in that, In step (3), the stirring reaction temperature of the amidation reaction is 25~35 ℃ and the reaction time is 70~74 h.

8. The application of the TEMPO-functionalized carbon support C-TEMPO particles as described in claim 1 in Faraday capacitor deionization ICC-FCDI electrode material.

9. The application according to claim 8, characterized in that, The electrode material is the negative electrode flow electrode material of ICC-FCDI.

10. The application according to claim 8, characterized in that, The electrode material is prepared by the following method: C-TEMPO particles and conductive additives are mixed at a mass ratio of 8~9:1, and then dispersed in deionized water containing sodium chloride. The mixture is stirred evenly to obtain a stable flowing electrode slurry, which is adapted to the independent closed-loop operation of ICC-FCDI.

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