MOF (Metal Organic Framework) derived carbon composite material formed based on impregnation method and application of MOF derived carbon composite material

Abstract

The invention relates to the technical field of water treatment, in particular to an MOF derived carbon composite material formed based on an impregnation method and application of the MOF derived carbon composite material. When a conventional activated carbon electrode material is used as a CDI electrode, the desalination efficiency is poor. In order to solve the technical problems, the MOF derived carbon composite material formed based on the impregnation method is provided, compared with a conventional metal oxide and MOF compounding process, the preparation process of the obtained MOF derived carbon composite material is different from the conventional metal oxide and MOF compounding process, the high-temperature carbonization opportunity and frequency of the composite material and the dosage ratio of MOF derived carbon to a potassium permanganate aqueous solution are different, and the preparation process is simple. The MOF-derived carbon and the potassium permanganate aqueous solution have obvious influence on the CDI desalination performance of the obtained MOF-derived carbon composite negative electrode plate, and experiments prove that when the dosage ratio of the MOF-derived carbon to the 0.005 mol / L potassium permanganate aqueous solution is 1: 10, and high-temperature carbonization is performed after dipping and compounding, the CDI desalination performance of the obtained MOF-derived carbon composite negative electrode plate is more excellent.

Description

Technical Field

[0001] The present invention relates to the technical field of water treatment, and particularly to a MOF-derived carbon composite material formed by an impregnation method and its application. Background Art

[0002] Capacitive deionization technology (CDI) is a water treatment technology based on the principle of electroadsorption. By applying an external electric field, charged ions in water are driven to migrate directionally and adsorbed on the surface of porous electrodes, thereby achieving efficient desalination or ion selective separation. Compared with traditional high-energy-consuming technologies such as reverse osmosis and distillation, CDI has the advantages of low energy consumption (<2V working voltage), simple operation, and environmental friendliness, and is particularly suitable for fields such as seawater desalination, brackish water treatment, and industrial wastewater reuse. Its core performance depends on the specific surface area, conductivity, and ion adsorption kinetic characteristics of the electrode material.

[0003] Traditional CDI electrodes mostly use activated carbon, carbon aerogel, or graphene, but are limited by problems such as low specific surface area utilization, poor electrochemical stability, and insufficient selectivity. In recent years, by introducing functionalized carbon-based composite materials (such as metal oxide / carbon, MOF-derived carbon, etc.) and combining ion intercalation and redox reaction synergistic adsorption mechanisms, the desalination efficiency and cycle life have been significantly improved.

[0004] With the increasing global water shortage, CDI technology has attracted much attention as a green desalination solution, and the development of high-performance electrode materials has become the key breakthrough point to promote its large-scale application. Summary of the Invention

[0005] The problem existing in the prior art is that the desalination efficiency of conventional activated carbon electrode materials as CDI electrodes is not good. To solve the above technical problems, the present invention provides a MOF-derived carbon composite material formed by an impregnation method, and its preparation method includes the following steps:

[0006] The MOF-derived carbon is completely impregnated in an aqueous potassium permanganate solution. After the impregnation is completed, the obtained solid product is washed with deionized water until the pH of the filtrate is constant, and then filtered and dried to obtain the product.

[0007] Preferably, the preparation method of the MOF-derived carbon includes the following steps:

[0008] (1) Zn(NO3)2·6H2O and terephthalic acid are added to an organic solvent, stirred evenly, then transferred to a high-pressure reaction kettle, and the high-pressure reaction kettle is placed at a high temperature for constant-temperature reaction. After the reaction is completed, the obtained reactants are successively subjected to centrifugal separation, washing, and solid-liquid separation, and the obtained solid product is vacuum-dried to obtain a MOF precursor;

[0009] (2) Place the MOF precursor above the quartz boat and calcine it at high temperature under the protection of inert gas or nitrogen. After the calcination is completed, MOF-derived carbon is obtained.

[0010] Preferably, in step (1), the mass ratio of Zn(NO3)2·6H2O to terephthalic acid is 4-6:1.

[0011] Preferably, the mass concentration of Zn(NO3)2·6H2O in the organic solvent is 74 ± 0.5 mg / mL.

[0012] Preferably, the organic solvent includes at least one of DMF, DMSO, ethanol, methanol, acetone, NMP, THF, dichloromethane, benzene, and toluene.

[0013] Preferably, the reaction temperature in step (1) is 120 ± 5 °C, and the reaction time is 14 ± 2 h.

[0014] Preferably, the calcination temperature in step (2) is in the range of 600-1000 °C, and the calcination time is 1-3 h.

[0015] Preferably, the concentration of the potassium permanganate aqueous solution is 0.005-0.03 mol / L, and the mass-volume ratio of potassium permanganate to the potassium permanganate aqueous solution is 0.79-4.47 g:1000 mL.

[0016] Preferably, the impregnation temperature is 25-80 °C, and the impregnation time is 1-12 h.

[0017] The present invention has the following beneficial effects:

[0018] (1) The MOF-derived carbon composite material obtained in the present invention has good desalination effect during the CDI application process, the preparation method is simple, the electrochemical stability is good, the recyclability is excellent, and it has good application prospects;

[0019] (2) The preparation process of the MOF-derived carbon composite material obtained in the present invention is different from the conventional composite process of metal oxides and MOFs. The timing and number of high-temperature carbonization of the composite material, as well as the dosage ratio between the MOF-derived carbon and the potassium permanganate aqueous solution, all have a significant impact on the CDI desalination performance of the obtained MOF-derived carbon composite negative electrode sheet. Experiments prove that when the dosage ratio of the MOF-derived carbon to the 0.005 mol / L potassium permanganate aqueous solution is 1:10, and after impregnation and composite and then high-temperature carbonization, the CDI desalination performance of the obtained MOF-derived carbon composite negative electrode sheet is more excellent. Description of the Drawings

[0020] Figure 1 : Physical picture of the MOF-derived carbon composite negative electrode sheet obtained in Example 1.

[0021] Figure 2Desalination performance and SAC test results of the MOF-derived carbon composite negative electrode sheets obtained in Examples 1-3. Detailed implementation mode

[0022] The present invention will be described in detail below with reference to embodiments. However, it should be understood that the following embodiments are only illustrative examples of the implementation modes of the present invention, rather than limiting the scope of the present invention.

[0023] Example 1

[0024] A MOF-derived carbon composite material formed by an impregnation method, and its preparation method is as follows:

[0025] (1) Add 5.95 g of Zn(NO3)2·6H2O and 1.15 g of terephthalic acid to 80 mL of DMF, stir evenly with a magnetic stirrer, then transfer it to an autoclave, and then place the autoclave in a constant temperature reaction at 120 °C for 14 h. After the reaction is completed, the obtained reactants are successively subjected to centrifugal separation, washed three times with DMF and ethanol respectively, vacuum filtered, and the obtained solid product is vacuum dried at 80 °C to obtain a MOF precursor;

[0026] (2) Place the MOF precursor above a quartz boat and perform high-temperature calcination under Ar protection. The calcination temperature is 800 °C and the calcination time is 2 h. After the calcination is completed, MOF-derived carbon is obtained;

[0027] (3) Immerse 5 g of MOF-derived carbon completely in 50 mL of 0.005 mol / L potassium permanganate aqueous solution. The impregnation temperature is 25 °C and the impregnation time is 12 h. After the impregnation is completed, the obtained solid product is washed with deionized water until the pH of the filtrate is constant, and then filtered through a 0.45 μm microporous filter membrane and dried at 70 °C for 6 h to obtain the MOF-derived carbon composite material, denoted as KMnO4-0.005.

[0028] Example 2

[0029] A MOF-derived carbon composite material formed by an impregnation method, and its preparation method is as follows:

[0030] (1) Add 5.95 g of Zn(NO3)2·6H2O and 1.15 g of terephthalic acid to 80 mL of DMF, stir evenly with a magnetic stirrer, then transfer it to an autoclave, and then place the autoclave in a constant temperature reaction at 120 °C for 14 h. After the reaction is completed, the obtained reactants are successively subjected to centrifugal separation, washed three times with DMF and ethanol respectively, vacuum filtered, and the obtained solid product is vacuum dried at 80 °C to obtain a MOF precursor;

[0031] (2) Place the MOF precursor above a quartz boat and conduct high-temperature calcination under Ar protection. The calcination temperature is 800 °C and the calcination time is 2 h. After the calcination is completed, MOF-derived carbon is obtained;

[0032] (3) Immerse 5 g of MOF-derived carbon completely in 50 mL of 0.01 mol / L potassium permanganate aqueous solution. The immersion temperature is 25 °C and the immersion time is 12 h. After the immersion is completed, the obtained solid product is washed with deionized water until the pH of the filtrate is constant, and then filtered through a 0.45 μm microporous filter membrane and dried at 70 °C for 6 h to obtain the MOF-derived carbon composite material, denoted as KMnO4-0.01.

[0033] Example 3

[0034] A MOF-derived carbon composite material formed by an impregnation method, and its preparation method is as follows:

[0035] (1) Add 5.95 g of Zn(NO3)2·6H2O and 1.15 g of terephthalic acid to 80 mL of DMF. After magnetic stirring evenly, transfer it to an autoclave, and then place the autoclave in a constant temperature reaction at 120 °C for 14 h. After the reaction is completed, the obtained reactants are successively centrifuged, washed three times with DMF and ethanol respectively, and vacuum filtered. After the obtained solid product is vacuum dried at 80 °C, a MOF precursor is obtained;

[0036] (2) Place the MOF precursor above a quartz boat and conduct high-temperature calcination under Ar protection. The calcination temperature is 800 °C and the calcination time is 2 h. After the calcination is completed, MOF-derived carbon is obtained;

[0037] (3) Immerse 5 g of MOF-derived carbon completely in 50 mL of 0.03 mol / L potassium permanganate aqueous solution. The immersion temperature is 25 °C and the immersion time is 12 h. After the immersion is completed, the obtained solid product is washed with deionized water until the pH of the filtrate is constant, and then filtered through a 0.45 μm microporous filter membrane and dried at 70 °C for 6 h to obtain the MOF-derived carbon composite material, denoted as KMnO4-0.03.

[0038] Example 4

[0039] A MOF-derived carbon composite material formed by an impregnation method, and its preparation method is as follows:

[0040] (1) 4.6 g of Zn(NO3)2·6H2O and 1.15 g of terephthalic acid were added to 80 mL of DMF. After being stirred evenly by magnetic force, it was then transferred into a high-pressure reactor. Then the high-pressure reactor was placed at 120 °C for a constant-temperature reaction for 14 h. After the reaction ended, the obtained reactants were successively subjected to centrifugal separation, washed three times each with DMF and ethanol, and vacuum filtered. The obtained solid product was dried in vacuo at 80 °C to obtain a MOF precursor;

[0041] (2) The MOF precursor was placed above a quartz boat and calcined at high temperature under Ar protection. The calcination temperature was 800 °C and the calcination time was 2 h. After the calcination ended, a MOF-derived carbon was obtained;

[0042] (3) 5 g of the MOF-derived carbon was completely impregnated in 50 mL of a 0.005 mol / L aqueous potassium permanganate solution. The impregnation temperature was 25 °C and the impregnation time was 12 h. After the impregnation was completed, the obtained solid product was washed with deionized water until the pH of the filtrate was constant, and then filtered through a 0.45 μm microporous membrane and dried at 70 °C for 6 h to obtain a MOF-derived carbon composite material - 4.

[0043] Example 5

[0044] A MOF-derived carbon composite material formed by an impregnation method, and its preparation method is as follows:

[0045] (1) 6.9 g of Zn(NO3)2·6H2O and 1.15 g of terephthalic acid were added to 80 mL of DMF. After being stirred evenly by magnetic force, it was then transferred into a high-pressure reactor. Then the high-pressure reactor was placed at 120 °C for a constant-temperature reaction for 14 h. After the reaction ended, the obtained reactants were successively subjected to centrifugal separation, washed three times each with DMF and ethanol, and vacuum filtered. The obtained solid product was dried in vacuo at 80 °C to obtain a MOF precursor;

[0046] (2) The MOF precursor was placed above a quartz boat and calcined at high temperature under Ar protection. The calcination temperature was 800 °C and the calcination time was 2 h. After the calcination ended, a MOF-derived carbon was obtained;

[0047] (3) 5 g of the MOF-derived carbon was completely impregnated in 50 mL of a 0.005 mol / L aqueous potassium permanganate solution. The impregnation temperature was 25 °C and the impregnation time was 12 h. After the impregnation was completed, the obtained solid product was washed with deionized water until the pH of the filtrate was constant, and then filtered through a 0.45 μm microporous membrane and dried at 70 °C for 6 h to obtain a MOF-derived carbon composite material - 5.

[0048] Example 6

[0049] A MOF-derived carbon composite material formed by an impregnation method, and its preparation method is as follows:

[0050] (1) 5.95 g of Zn(NO3)2·6H2O and 1.15 g of terephthalic acid were added to 80 mL of DMF. After magnetic stirring until homogeneous, the mixture was transferred to a high-pressure reactor, which was then maintained at 125 °C for 14 h. After the reaction, the obtained reactants were successively centrifuged, washed three times each with DMF and ethanol, vacuum filtered, and the obtained solid product was dried under vacuum at 80 °C to obtain the MOF precursor;

[0051] (2) The MOF precursor was placed above a quartz boat and calcined at high temperature under Ar protection. The calcination temperature was 800 °C and the calcination time was 2 h. After calcination, MOF-derived carbon was obtained;

[0052] (3) 5 g of MOF-derived carbon was completely impregnated in 50 mL of 0.005 mol / L potassium permanganate aqueous solution at an impregnation temperature of 25 °C for 12 h. After impregnation, the obtained solid product was washed with deionized water until the pH of the filtrate was constant, then filtered through a 0.45 μm microporous membrane and dried at 70 °C for 6 h to obtain the MOF-derived carbon composite material - 6.

[0053] Example 7

[0054] A MOF-derived carbon composite material formed by an impregnation method, and its preparation method is as follows:

[0055] (1) 5.95 g of Zn(NO3)2·6H2O and 1.15 g of terephthalic acid were added to 80 mL of DMF. After magnetic stirring until homogeneous, the mixture was transferred to a high-pressure reactor, which was then maintained at 115 °C for 14 h. After the reaction, the obtained reactants were successively centrifuged, washed three times each with DMF and ethanol, vacuum filtered, and the obtained solid product was dried under vacuum at 80 °C to obtain the MOF precursor;

[0056] (2) The MOF precursor was placed above a quartz boat and calcined at high temperature under Ar protection. The calcination temperature was 800 °C and the calcination time was 2 h. After calcination, MOF-derived carbon was obtained;

[0057] (3) 5 g of MOF-derived carbon was completely impregnated in 50 mL of 0.005 mol / L potassium permanganate aqueous solution at an impregnation temperature of 25 °C for 12 h. After impregnation, the obtained solid product was washed with deionized water until the pH of the filtrate was constant, then filtered through a 0.45 μm microporous membrane and dried at 70 °C for 6 h to obtain the MOF-derived carbon composite material - 7.

[0058] Example 8

[0059] A MOF-derived carbon composite formed by an impregnation method, and its preparation method is as follows:

[0060] (1) Add 5.95 g of Zn(NO3)2·6H2O and 1.15 g of terephthalic acid to 80 mL of DMF. After magnetic stirring until uniform, transfer it to a high-pressure reaction kettle. Then place the high-pressure reaction kettle in a constant-temperature reaction at 120 °C for 14 h. After the reaction is completed, the obtained reactants are successively subjected to centrifugal separation, washed three times with DMF and ethanol respectively, vacuum filtered, and the obtained solid product is vacuum dried at 80 °C to obtain a MOF precursor;

[0061] (2) Place the MOF precursor above a quartz boat and perform high-temperature calcination under Ar protection. The calcination temperature is 1000 °C and the calcination time is 2 h. After the calcination is completed, MOF-derived carbon is obtained;

[0062] (3) Completely immerse 5 g of MOF-derived carbon in 50 mL of 0.005 mol / L potassium permanganate aqueous solution. The impregnation temperature is 25 °C and the impregnation time is 12 h. After the impregnation is completed, the obtained solid product is washed with deionized water until the pH of the filtrate is constant, and then filtered through a 0.45 μm microporous filter membrane and dried at 70 °C for 6 h to obtain the MOF-derived carbon composite - 8.

[0063] Example 9

[0064] A MOF-derived carbon composite formed by an impregnation method, and its preparation method is as follows:

[0065] (1) Add 5.95 g of Zn(NO3)2·6H2O and 1.15 g of terephthalic acid to 80 mL of DMF. After magnetic stirring until uniform, transfer it to a high-pressure reaction kettle. Then place the high-pressure reaction kettle in a constant-temperature reaction at 120 °C for 14 h. After the reaction is completed, the obtained reactants are successively subjected to centrifugal separation, washed three times with DMF and ethanol respectively, vacuum filtered, and the obtained solid product is vacuum dried at 80 °C to obtain a MOF precursor;

[0066] (2) Place the MOF precursor above a quartz boat and perform high-temperature calcination under Ar protection. The calcination temperature is 800 °C and the calcination time is 2 h. After the calcination is completed, MOF-derived carbon is obtained;

[0067] (3) Completely immerse 5 g of MOF-derived carbon in 50 mL of 0.005 mol / L potassium permanganate aqueous solution. The impregnation temperature is 25 °C and the impregnation time is 12 h. After the impregnation is completed, the obtained solid product is washed with deionized water until the pH of the filtrate is constant, and then filtered through a 0.45 μm microporous filter membrane and dried at 70 °C for 6 h to obtain the MOF-derived carbon composite - 9.

[0068] Example 10

[0069] A MOF-derived carbon composite formed by an impregnation method, and its preparation method is as follows:

[0070] (1) Add 5.95 g of Zn(NO3)2·6H2O and 1.15 g of terephthalic acid to 80 mL of DMF. After magnetic stirring until uniform, transfer it to a high-pressure reaction kettle. Then place the high-pressure reaction kettle in a constant temperature reaction at 120 °C for 14 h. After the reaction is completed, the obtained reactants are successively subjected to centrifugal separation, washed three times with DMF and ethanol respectively, vacuum filtered. After the obtained solid product is vacuum dried at 80 °C, a MOF precursor is obtained;

[0071] (2) Place the MOF precursor above the quartz boat and carry out high-temperature calcination under Ar protection. The calcination temperature is 800 °C and the calcination time is 2 h. After the calcination is completed, MOF-derived carbon is obtained;

[0072] (3) Completely immerse 5 g of MOF-derived carbon in 50 mL of 0.005 mol / L potassium permanganate aqueous solution. The impregnation temperature is 50 °C and the impregnation time is 12 h. After the impregnation is completed, the obtained solid product is washed with deionized water until the pH of the filtrate is constant, and then filtered through a 0.45 μm microporous filter membrane and dried at 70 °C for 6 h to obtain MOF-derived carbon composite-10.

[0073] Example 11

[0074] A MOF-derived carbon composite formed by an impregnation method, and its preparation method is as follows:

[0075] (1) Add 5.95 g of Zn(NO3)2·6H2O and 1.15 g of terephthalic acid to 80 mL of DMF. After magnetic stirring until uniform, transfer it to a high-pressure reaction kettle. Then place the high-pressure reaction kettle in a constant temperature reaction at 120 °C for 14 h. After the reaction is completed, the obtained reactants are successively subjected to centrifugal separation, washed three times with DMF and ethanol respectively, vacuum filtered. After the obtained solid product is vacuum dried at 80 °C, a MOF precursor is obtained;

[0076] (2) Place the MOF precursor above the quartz boat and carry out high-temperature calcination under Ar protection. The calcination temperature is 800 °C and the calcination time is 2 h. After the calcination is completed, MOF-derived carbon is obtained;

[0077] (3) Completely immerse 5 g of MOF-derived carbon in 50 mL of 0.005 mol / L potassium permanganate aqueous solution. The impregnation temperature is 80 °C and the impregnation time is 12 h. After the impregnation is completed, the obtained solid product is washed with deionized water until the pH of the filtrate is constant, and then filtered through a 0.45 μm microporous filter membrane and dried at 70 °C for 6 h to obtain MOF-derived carbon composite-11.

[0078] Comparative Example 1 is the same as Example 1, except that the preparation method of the MOF-derived carbon composite material in Comparative Example 1 is as follows:

[0079] (1) 5.95 g of Zn(NO3)2·6H2O and 1.15 g of terephthalic acid were added to 80 mL of DMF, and after magnetic stirring until homogeneous, it was then transferred into a high-pressure reaction kettle. Then, the high-pressure reaction kettle was placed at a constant temperature of 120 °C for 14 h. After the reaction ended, the obtained reactants were successively subjected to centrifugal separation, washed three times each with DMF and ethanol, vacuum filtered, and the obtained solid product was dried under vacuum at 80 °C to obtain a MOF precursor;

[0080] (2) The MOF precursor was placed above the quartz boat and calcined at high temperature under Ar protection. The calcination temperature was 600 °C and the calcination time was 1 h. After the calcination ended, MOF-derived carbon was obtained;

[0081] (3) 5 g of the MOF-derived carbon was completely impregnated in 50 mL of a 0.005 mol / L potassium permanganate aqueous solution. The impregnation temperature was 25 °C and the impregnation time was 12 h. After the impregnation was completed, the obtained solid product was washed with deionized water until the pH of the filtrate was constant, then filtered through a 0.45 μm microporous filter membrane, dried at 70 °C for 6 h, and then placed in a tube furnace and calcined at 500 °C for 4 h under nitrogen protection to obtain a MOF-derived carbon composite material - Control 1.

[0082] Comparative Example 2 is the same as Example 1, except that the preparation method of the MOF-derived carbon composite material in Comparative Example 2 is as follows:

[0083] (1) 5.95 g of Zn(NO3)2·6H2O and 1.15 g of terephthalic acid were added to 80 mL of DMF, and after magnetic stirring until homogeneous, it was then transferred into a high-pressure reaction kettle. Then, the high-pressure reaction kettle was placed at a constant temperature of 120 °C for 14 h. After the reaction ended, the obtained reactants were successively subjected to centrifugal separation, washed three times each with DMF and ethanol, vacuum filtered, and the obtained solid product was dried under vacuum at 80 °C to obtain a MOF precursor;

[0084] (2) The MOF precursor was placed above the quartz boat and calcined at high temperature under Ar protection. The calcination temperature was 600 °C and the calcination time was 2 h. After the calcination ended, MOF-derived carbon was obtained;

[0085] (3) Completely immerse 5 g of MOF-derived carbon in 50 mL of an aqueous solution of potassium permanganate with a concentration of 0.005 mol / L at an impregnation temperature of 25 °C for 12 h. After impregnation, the obtained solid product is washed with deionized water until the pH of the filtrate is constant, then filtered through a 0.45-μm microporous membrane and dried at 70 °C for 6 h, and then calcined in a tubular furnace at 600 °C for 3 h under nitrogen protection to obtain the MOF-derived carbon composite material - Control 2.

[0086] Mix the MOF-derived carbon composite materials obtained in the above examples and comparative examples of the present invention with acetylene black and polytetrafluoroethylene in a mass ratio of 8:1:1, pour them into a 10-mL centrifuge tube, add 3 mL of ethanol, and ultrasonicate for 10 min. During the ultrasonic process, two drops of PVDF binder (purchased from Cyber Electrochemical Materials Network, product number D210C) are dropped in twice. Then, stir the mixture into a uniform paste and evenly apply it on the surface of a pre-cut and clean graphite paper (with a thickness of 1 mm and a size of 5 cm × 5 cm). Finally, dry the graphite paper in a blast dryer at 60 °C to obtain the MOF-derived carbon composite negative electrode sheet. The physical diagram of the MOF-derived carbon composite negative electrode sheet obtained in Example 1 is as shown in the Figure 1 specification appendix.

[0087] Perform desalination performance tests on the MOF-derived carbon composite negative electrode sheets obtained in the examples and comparative examples of the present invention. The test method is as follows:

[0088] The initial conductivity of the test brine (aqueous sodium chloride solution with a concentration of 700 mg / L) is 1000 μS / cm. Under a DC voltage of 1.2 V, test the adsorption and regeneration curves (the test results of the MOF-derived carbon composite negative electrode sheet obtained in Example 1 are as shown in the Figure 2 specification appendix). Calculated, under a DC voltage of 1.2 V for adsorption and desorption, the adsorption capacities of Examples 1-11 and Comparative Examples 1-2 are 38.5 mg / g, 40.3 mg / g, 42.1 mg / g, 35.8 mg / g, 37.2 mg / g, 39.8 mg / g, 36.0 mg / g, 34.5 mg / g, 38.9 mg / g, 38.7 mg / g, 38.6 mg / g, 21.5 mg / g, and 24.3 mg / g respectively. This value is much higher than that of conventional activated carbon electrode materials (<10 mg / g); most importantly, after 100 adsorption and desorption cycles, the MOF-derived carbon composite negative electrode sheets obtained in Examples 1-11 have good regeneration performance.

[0089] The preparation method of the positive electrode sheet used in the desalination performance test is as follows:

[0090] The MOF-derived carbon composite material is mixed with acetylene black and polytetrafluoroethylene in a mass ratio of 8:1:1, and then poured into a 10 mL centrifuge tube. 3 mL of ethanol is added, and the mixture is ultrasonically treated for 10 min. During the ultrasonic treatment, two or three drops of PVDF binder (purchased from Cyber Electrochemical Materials Network, product number D210C) are dropped at intervals. Then, the mixture is stirred into a uniform paste and evenly coated on the surface of a pre-cut and clean graphite paper (with a thickness of 1 mm and a size of 5 cm × 5 cm). Finally, the graphite paper is dried in a blast dryer at 60 °C to obtain the MOF-derived carbon composite negative electrode sheet.

[0091] The test results of the specific area capacitance SAC of the negative electrode sheets obtained in Examples 1-11 and Comparative Examples 1-2 are 14.2 mg / L, 15.6 mg / L, 16.8 mg / L, 13.4 mg / L, 13.8 mg / L, 15.0 mg / L, 13.5 mg / L, 12.9 mg / L, 14.5 mg / L, 14.3 mg / L, 14.2 mg / L, 7.8 mg / L, and 8.5 mg / L respectively. The specific calculation method is as follows:

[0092]

[0093] C0: Concentration of the initial brine solution (mg / L);

[0094] C t : Concentration of the brine solution after adsorption (mg / L);

[0095] V: Volume of the brine solution (L);

[0096] M: Mass of the electrode material (g).

[0097] Inspired by the ideal embodiments of the present invention described above, through the above description, relevant staff can make various changes and modifications completely within the scope not deviating from the technical idea of this invention. The technical scope of this invention is not limited to the content in the specification, and its technical scope must be determined according to the scope of the claims.

Claims

1. A MOF-derived carbon composite formed by an impregnation method, characterized in that, The preparation method comprises the following steps: Completely immerse the MOF-derived carbon in an aqueous solution of potassium permanganate. After immersion, wash the obtained solid product with deionized water until the pH of the filtrate is constant, and then filter and dry to obtain the product.

2. A MOF-derived carbon composite material formed by an impregnation method according to claim 1, characterized in that, The preparation method of the MOF-derived carbon comprises the following steps: (1) Add Zn(NO3)2·6H2O and terephthalic acid to an organic solvent, stir evenly, then transfer to an autoclave, and place the autoclave in a constant temperature reaction at a high temperature. After the reaction is completed, the obtained reactants are successively subjected to centrifugal separation, washing, and solid-liquid separation. The obtained solid product is dried in vacuo to obtain a MOF precursor; (2) Place the MOF precursor above a quartz boat and perform high-temperature calcination under the protection of an inert gas or nitrogen. After the calcination is completed, MOF-derived carbon is obtained.

3. The MOF-derived carbon composite material formed by the impregnation method according to claim 2, wherein In step (1), the mass ratio of Zn(NO3)2·6H2O to terephthalic acid is 4-6:

1.

4. A MOF-derived carbon composite material formed by an impregnation method according to claim 2, characterized in that, The mass concentration of Zn(NO3)2·6H2O in the organic solvent is 74±0.5 mg / mL.

5. The MOF-derived carbon composite material formed by the impregnation method according to claim 2, characterized in that, The organic solvent includes at least one of DMF, DMSO, ethanol, methanol, acetone, NMP, THF, dichloromethane, benzene, and toluene.

6. The MOF-derived carbon composite material formed by the impregnation method according to claim 2, characterized in that, The reaction temperature in step (1) is 120±5 °C, and the reaction time is 14±2 h.

7. A MOF-derived carbon composite material formed by an impregnation method according to claim 2, characterized in that The calcination temperature in step (2) is in the range of 600-1000 °C, and the calcination time is in the range of 1-3 h.

8. A MOF-derived carbon composite material formed by an impregnation method according to claim 1, characterized in that The concentration of the aqueous potassium permanganate solution is 0.005-0.03 mol / L, and the mass-volume ratio of potassium permanganate to the aqueous potassium permanganate solution is 0.79-4.47 g:1000 mL.

9. A MOF-derived carbon composite material formed by an impregnation method according to claim 1, characterized in that, The immersion temperature is 25-80 °C, and the immersion time is 1-12 h.

10. A MOF-derived carbon composite negative electrode sheet, characterized in that, It is obtained by uniformly mixing the MOF-derived carbon composite material obtained in any one of claims 1-9 with a conductive agent and a binder, uniformly coating the mixture on the surface of a current collector, and then drying and pressing into a sheet.

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