A carbon-based electrode of prussian blue analogue and a preparation method and application thereof

Abstract

The application discloses a Prussian blue analogue carbon electrode and a preparation method and application thereof, and belongs to the technical field of electrode preparation of capacitive deionization. The Prussian blue analogue carbon electrode takes carbon material as a substrate, and in-situ loading of Prussian blue analogue is arranged on the carbon material substrate. The morphological structure of the Prussian blue analogue is nanoparticle clusters, and the particle size is 30-200 nm. The Prussian blue analogue is a transition metal doped Prussian blue. The preparation method of the Prussian blue analogue carbon electrode is that the Prussian blue analogue is in-situ loaded on the carbon material substrate through one-step hydrothermal reaction. The Prussian blue analogue carbon electrode has excellent electric conductivity, sodium ion adsorption performance and electrochemical stability.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of electrode preparation of capacitive deionization, in particular to a Prussian blue analogue carbon-based electrode and a preparation method and application thereof. BACKGROUND

[0002] With the increasing global water resource problems, membrane capacitive deionization technology as an energy-saving, environmentally friendly and cost-effective seawater desalination technology has been widely concerned by researchers. The basic principle of capacitive deionization (CDI) technology is to form a double electric layer on a carbon-based electrode to capture salt ions. Limited by the inherent capacity of traditional carbon materials, the adsorption capacity of the electrode and the desalination rate in the desalination process have not reached the level of widespread application. Therefore, improving the performance of the electrode material is crucial to the improvement of the CDI desalination capacity.

[0003] Prussian blue, as an electrode material with an open framework structure, has large interstitial sites which are conducive to the rapid deintercalation of metal cations such as Na + , K + and the like. Therefore, Prussian blue and its analogues as CDI electrode materials can convert the physical adsorption of the double electric layer of traditional carbon-based electrodes into pseudo-capacitive adsorption of redox reactions on the surface of the electrode material, which can greatly improve the electrode adsorption capacity. However, due to its poor electrical conductivity and low electron transfer rate, its electrochemical performance is limited, which seriously restricts its practical application. Therefore, Prussian blue-based materials as electrodes are usually mixed with conductive agents (carbon black) and attached to the electrode through a binder (such as PVDF, PTFE).

[0004] The commonly used binder in the electrode is polyvinylidene fluoride (PVDF), which is a high molecular weight oily binder. In addition to ensuring the adhesive action between the active material and the current collector, it can also ensure the safety and uniformity of the active material slurry. However, its electrochemical stability at high temperatures is poor, which can lead to the generation of side reactions inside the electrode. In addition, PVDF itself is an electronically insulating compound, and its addition can occupy the reaction sites of the electrode material and reduce the electrical conductivity of the electrode. These factors have resulted in the unsatisfactory performance of the current Prussian blue-based electrode. Therefore, it is necessary to develop a Prussian blue-based electrode with good electrical conductivity and stability and a preparation method thereof. SUMMARY

[0005] The purpose of the present application is to provide a Prussian blue analogue carbon-based electrode without binder and a preparation method and application thereof, aiming to improve the electrical conductivity and stability of the material electrode, and further solve the problems of small electrode adsorption capacity and short service life in the CDI desalination system. To solve the problems existing in the prior art.

[0006] To achieve the above purpose, the present application provides the following solutions:

[0007] One of the technical solutions of the present application: a Prussian blue analogue carbon electrode, using carbon material as the substrate, and in-situ loading Prussian blue analogue on the carbon material substrate; the morphological structure of the Prussian blue analogue is nanoparticle clusters, and the particle size is 30-200 nm; the Prussian blue analogue is a transition metal doped Prussian blue.

[0008] Further, the loading amount of the Prussian blue analogue is 2-8 mg / cm 2 .

[0009] Further, the transition metal doped Prussian blue is one of nickel (Ni) doped Prussian blue, magnesium (Mg) doped Prussian blue, copper (Cu) doped Prussian blue, cobalt (Co) doped Prussian blue, and zinc (Zn) doped Prussian blue.

[0010] The doping of transition metal replaces Fe 2+ connected to N in potassium ferricyanide, and by adjusting the crystal lattice structure of Prussian blue, the ion capacity of the electrode material can be improved, and the cycle stability and rate performance of the material can be improved.

[0011] The second technical solution of the present application: a preparation method of the above-mentioned Prussian blue analogue carbon electrode, in which Prussian blue analogue is in-situ loaded on the carbon material substrate through one-step hydrothermal reaction to obtain the Prussian blue analogue carbon electrode.

[0012] Further, the in-situ loading of Prussian blue analogue on the carbon material substrate through one-step hydrothermal reaction includes: activating the carbon material substrate, soaking the activated carbon material substrate in potassium ferricyanide aqueous solution, then adding transition metal salt solution and carboxylic acid solution, and heating for hydrothermal reaction to obtain the Prussian blue analogue carbon electrode.

[0013] Further, when the activated carbon material substrate is soaked in the potassium ferricyanide aqueous solution, there is no special limitation on the dosage ratio of the carbon substrate material to the potassium ferricyanide aqueous solution, as long as the potassium ferricyanide aqueous solution can completely soak the carbon substrate, and there is no part exposed to the air.

[0014] Further, the concentration of the potassium ferricyanide aqueous solution is 0.005-0.05 M; and the soaking time is 1-5 h.

[0015] Further, the transition metal salt solution is a nickel salt solution, a magnesium salt solution, a copper salt solution, a cobalt salt solution, or a zinc salt solution; the carboxylic acid solution is an aqueous solution of one or more of formic acid, acetic acid, propionic acid, and butyric acid; the concentrations of the transition metal salt solution and the carboxylic acid solution are the same as that of the potassium ferricyanide aqueous solution; and the volume ratio of the potassium ferricyanide aqueous solution, the transition metal salt solution, and the carboxylic acid solution is 1:1.5-2.5:0.5-1.

[0016] Further, the nickel salt solution is an aqueous solution of one or more of nickel nitrate, nickel chloride, and nickel carbonate.

[0017] Further, the temperature of the hydrothermal reaction is 55-65℃, and the time is 5-8h.

[0018] Further, the activation of the carbon material substrate comprises: sequentially immersing the carbon material substrate in acetone, ethanol, and water, ultrasonic treatment, drying, then heating and immersing in an HNO3 solution, washing, and drying.

[0019] Further, the concentration of the HNO3 solution is 5-8M; the temperature of the heating and immersing is 75-85℃, and the time is 2-4h.

[0020] The purpose of activating the carbon material substrate is to introduce oxygen-containing functional groups on the carbon material substrate and improve the hydrophilic property of the carbon material substrate.

[0021] Further, the water is deionized water; and the time of the ultrasonic treatment is 20-40min.

[0022] Further, the specific operation of the drying is: drying at 65-75℃ overnight.

[0023] Further, the carbon material substrate is carbon cloth, carbon felt, or carbon fiber.

[0024] The reaction principle of in-situ generation of Prussian blue analogues by one-step hydrothermal reaction (taking a transition metal chloride salt as an example) is as follows:

[0025] K3[Fe(CN)6]+MCl x →K 3-x M[Fe(CN)6] 1-y □ y ·nH2O+xCl - +xK +

[0026] (1<x<3, 0<y<1), wherein M is various transition metals such as nickel, magnesium, and copper, and □ is a lattice vacancy occupied by coordination water. By adjusting the ratio of raw materials and reaction conditions, the morphology and size of the generated Prussian blue analogue can be adjusted, so that the Prussian blue analogue is loaded on the carbon material substrate in the form of a nanoparticle cluster, and the particle size is controlled to be 30-200nm.

[0027] The third technical scheme of the present application is: an application of the above-mentioned Prussian blue analogue carbon-based electrode in capacitive deionization (CDI).

[0028] Further, the Prussian blue analogue carbon-based electrode is applied as a cathode of the CDI system. When a film material is contained in the battery device of the CDI system, it is also called a membrane capacitive deionization (MCDI) system.

[0029] Further, the voltage applied in the capacitive deionization process is 0.8-1.4 V; and the flow rate of the salt solution is 0.2-10 mL / min.

[0030] The present application discloses the following technical effects:

[0031] (1) The Prussian blue analogue carbon-based electrode provided by the present application is a kind of composite material of transition metal doped Prussian blue and carbon material, wherein, the transition metal doping changes the crystal structure of Prussian blue itself, greatly improves the conductivity and sodium ion adsorption performance of Prussian blue itself, and the combination of Prussian blue analogue and carbon material makes the advantages of the two complementary, Prussian blue analogue endows the composite material with better sodium ion adsorption performance, and carbon material further improves the conductivity of the composite material, so that the Prussian blue analogue carbon-based electrode of the present application has excellent conductivity and sodium ion adsorption performance.

[0032] (2) The present application grows Prussian blue analogue on the carbon material substrate by one-step hydrothermal reaction to obtain a composite electrode material, the preparation process is simple and easy to operate; the loading amount of active material Prussian blue analogue can be controlled by changing the concentration of precursor solution, which is easy to optimize and free to control; in addition, the Prussian blue analogue particles generated by the preparation method of the present application exist in the form of nanoparticle clusters on the carbon material substrate structure, and the electrochemical property is stable and can exist stably in the salt solution for a long time. BRIEF DESCRIPTION OF DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments will be briefly introduced as follows. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0034] Figure 1 SEM image of the NiHCF-carbon cloth electrode prepared in Example 1 of the present application;

[0035] Figure 2 XRD pattern of NiHCF-carbon cloth electrode prepared for Example 1 of the present invention;

[0036] Figure 3 CV pattern of NiHCF-carbon cloth electrode in Application Example 1 of the present invention;

[0037] Figure 4 GCD pattern of NiHCF-carbon cloth electrode in Application Example 1 of the present invention;

[0038] Figure 5 Conductivity and current test data pattern in Application Example 1 of the present invention, wherein (a) is the conductivity change pattern, (b) is the current change pattern;

[0039] Figure 6 Conductivity and current test data pattern in Application Example 2 of the present invention, wherein (a) is the conductivity change pattern, (b) is the current change pattern;

[0040] Figure 7 Conductivity and current test data pattern in Application Example 3 of the present invention, wherein (a) is the conductivity change pattern, (b) is the current change pattern;

[0041] Figure 8 Conductivity and current test data pattern in Comparative Application Example 1 of the present invention, wherein (a) is the conductivity change pattern, (b) is the current change pattern;

[0042] Figure 9 Conductivity and current test data pattern in Comparative Application Example 2 of the present invention, wherein (a) is the conductivity change pattern, (b) is the current change pattern;

[0043] Figure 10 Conductivity and current test data pattern in Comparative Application Example 3 of the present invention, wherein (a) is the conductivity change pattern, (b) is the current change pattern;

[0044] Figure 11 Conductivity and current test data pattern in Comparative Application Example 4 of the present invention, wherein (a) is the conductivity change pattern, (b) is the current change pattern;

[0045] Figure 12 Stability test results of NiHCF-carbon cloth electrode prepared for Example 1 of the present invention. DETAILED DESCRIPTION

[0046] Various exemplary embodiments of the present invention will now be described in detail, which should be considered as non-limiting examples of the present invention, and should be understood as a more detailed description of certain aspects, features and embodiments of the present invention.

[0047] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present application. Additionally, for a range of values of, for example, concentrations, amounts, and other

[0048] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application, the preferred methods and materials are described. All publications mentioned herein are incorporated by reference to disclose and describe the methods and / or materials in connection with which the publications are cited. The citation of any reference is not an admission that it is prior art with respect to the present application.

[0049] Many modifications and variations of this application of the application can be made without departing from its spirit or scope, which will be apparent to those skilled in the art. Other embodiments of the application will be apparent to those skilled in the art from consideration of the specification and practice of the application disclosed herein. For example, the specification and examples are illustrative only and do not limit the scope of the application. The specification and examples do not limit the scope of the application.

[0050] As used herein, the terms "comprise", "comprising", "include", "including", "have", "having" and the like are open-ended and do not exclude additional, unrecited elements or method steps.

[0051] Each of the raw materials used in the following examples and comparative examples is a general commercially available product.

[0052] Example 1

[0053] Preparation of Prussian blue analog (nickel-doped Prussian blue) carbon-based electrode (potassium nickel hexacyanoferrate (NiHCF)-carbon cloth electrode)

[0054] (1) Activation of carbon cloth substrate: The carbon cloth was immersed in acetone, ethanol, and deionized water successively and ultrasonically washed for 30 min. The cleaned carbon cloth was dried at 70 °C overnight. The dried carbon cloth was placed in a 6 M HNO3solution and reacted at 80 °C for 3 h. Finally, the carbon cloth was taken out, washed with deionized water, and dried at 70 °C overnight to obtain the activated carbon cloth substrate.

[0055] (2) 1 x 5 cm 2 The activated carbon cloth was immersed in 20 mL of 0.01 M K3[Fe(CN)6] aqueous solution for 3 h. The K3[Fe(CN)6] aqueous solution with the carbon cloth was denoted as solution A.

[0056] (3) Respectively, 40 mL, 0.01M of Ni(NO3)2 aqueous solution and 10 mL, 0.01M of acetic acid aqueous solution were added dropwise into the A solution, and 300 r / min magnetic stirring was carried out for 10 min. At this time, the solution was recorded as B solution.

[0057] (4) The B solution was transferred to a hydrothermal reactor, and hydrothermal reaction was carried out at 60℃ for 6h in an oven. After cooling to room temperature, the sample was washed with deionized water, and freeze-drying was carried out to obtain a Prussian blue analogue (nickel-doped Prussian blue) carbon-based electrode (NiHCF-carbon cloth electrode). In the electrode, the loading amount of the Prussian blue analogue (nickel-doped Prussian blue) on the carbon cloth substrate was 2.5 mg / cm 2 . The SEM image of the Prussian blue analogue (nickel-doped Prussian blue) carbon-based electrode is shown in Figure 1 , and Figure 1 it can be seen that the morphology of the Prussian blue analogue (nickel-doped Prussian blue) loaded on the carbon cloth substrate is a nanoparticle cluster, and the particle size is 30-50 nm. The XRD image is shown in Figure 2 , and Figure 2 it can be seen that the diffraction peaks of the Prussian blue analogue (nickel-doped Prussian blue) are similar to the diffraction peaks of KNiFe(CN)6 and Ni2[Fe(CN)6]·0.5H2O on the (111), (202), (220), (400) crystal planes, indicating that the Prussian blue analogue generated on the carbon cloth substrate is nickel-doped Prussian blue.

[0058] Example 2

[0059] Preparation of a Prussian blue analogue (nickel-doped Prussian blue) carbon-based electrode (potassium nickel hexacyanoferrate (NiHCF)-carbon felt electrode)

[0060] (1) Activation of carbon felt substrate: The carbon felt was immersed in acetone, ethanol and deionized water for ultrasonic washing for 30 min. The cleaned carbon felt was dried at 70℃ overnight. The dried carbon felt was placed in 6M HNO3 solution, and reacted at 80℃ for 3h. Finally, the carbon felt was taken out, washed with deionized water, and dried at 70℃ overnight to obtain the activated carbon cloth substrate.

[0061] (2) 1×5 cm 2 of the activated carbon felt was immersed in 15 mL of 0.02M K3[Fe(CN)6] aqueous solution for 3h. The K3[Fe(CN)6] aqueous solution with the carbon felt was recorded as A solution.

[0062] (3) Respectively, 30 mL, 0.02M of Ni(NO3)2 aqueous solution and 15 mL, 0.02M of acetic acid aqueous solution were added dropwise into the A solution, and 300 r / min magnetic stirring was carried out for 10 min. At this time, the solution was recorded as B solution.

[0063] (4) The B solution was transferred to a hydrothermal reactor, and hydrothermal reaction was carried out at 60°C for 6h in an oven. After cooling to room temperature, the sample was washed with deionized water, and freeze-dried to obtain a Prussian blue analogue (nickel-doped Prussian blue) carbon-based electrode (NiHCF-carbon felt electrode). In this electrode, the loading amount of the Prussian blue analogue (nickel-doped Prussian blue) on the carbon felt substrate was 4mg / cm 2 The morphology of the Prussian blue analogue (nickel-doped Prussian blue) loaded on the carbon felt substrate was a nanoparticle cluster, and the particle size was 50-100nm.

[0064] Example 3

[0065] Preparation of a Prussian blue analogue carbon-based electrode (potassium ferricyanide (FeHCF)-carbon cloth electrode)

[0066] (1) Activation of the carbon cloth substrate: The carbon cloth was immersed in acetone, ethanol, and deionized water in sequence and ultrasonically washed for 30min. The cleaned carbon cloth was dried at 70°C overnight. The dried carbon cloth was placed in a 6M HNO3 solution and reacted at 80°C for 3h. Finally, the carbon cloth was taken out, washed with deionized water, and dried at 70°C overnight to obtain the activated carbon cloth substrate.

[0067] (2) A piece of 1×5cm 2 The activated carbon cloth was immersed in 15mL of 0.04M K3[Fe(CN)6] aqueous solution for 3h. This K3[Fe(CN)6] aqueous solution with the carbon cloth was denoted as solution A.

[0068] (3) 30mL of 0.04M Ni(NO3)2 aqueous solution and 15mL of 0.04M formic acid aqueous solution were added dropwise into solution A, respectively, and stirred at 300r / min for 10min. The solution at this time was denoted as solution B.

[0069] (4) The B solution was transferred to a hydrothermal reactor, and hydrothermal reaction was carried out at 60°C for 6h in an oven. After cooling to room temperature, the sample was washed with deionized water, and freeze-dried to obtain a Prussian blue analogue (nickel-doped Prussian blue) carbon-based electrode (NiHCF-carbon felt electrode). In this electrode, the loading amount of the Prussian blue analogue (nickel-doped Prussian blue) on the carbon felt substrate was 4mg / cm 2 The morphology of the Prussian blue analogue (nickel-doped Prussian blue) loaded on the carbon felt substrate was a nanoparticle cluster, and the particle size was 50-100nm.

[0070] Comparative Example 1

[0071] Preparation of a Prussian blue carbon-based electrode (potassium ferricyanide (FeHCF)-carbon cloth electrode)

[0072] (1) Activation of carbon cloth substrate: The carbon cloth was immersed in acetone, ethanol, and deionized water successively and ultrasonically washed for 30 min. The cleaned carbon cloth was placed in a 70 °C oven to dry overnight. The dried carbon cloth was placed in a 6 M HNO3solution and reacted at 80 °C for 3 h. Finally, the carbon cloth was taken out, washed with deionized water, and dried at 70 °C overnight to obtain the activated carbon cloth substrate.

[0073] (2) The activated carbon cloth was immersed in 20 mL of 0.01 M aqueous K3[Fe(CN)6] solution for 3 h. The K3[Fe(CN)6] aqueous solution with the immersed carbon cloth was denoted as solution A. 2 The activated carbon cloth was immersed in 20 mL of 0.01 M aqueous K3[Fe(CN)6] solution for 3 h. The K3[Fe(CN)6] aqueous solution with the immersed carbon cloth was denoted as solution A.

[0074] (3) 40 mL of deionized water solution and 10 mL of 0.01 M aqueous acetic acid solution were added dropwise into solution A, respectively, and stirred magnetically at 300 r / min for 10 min. The solution at this time was denoted as solution B.

[0075] (4) Solution B was transferred to a hydrothermal reactor and reacted hydrothermally at 60 °C for 6 h. After cooling to room temperature, the sample was washed with deionized water and freeze-dried to obtain a Prussian blue carbon-based electrode (FeHCF-carbon cloth electrode). In this electrode, the loading amount of Prussian blue on the carbon cloth substrate was 1.2 mg / cm2. 2 The morphology of the Prussian blue loaded on the carbon cloth substrate was a nanoparticle cluster, and the particle size was 30-50 nm.

[0076] Comparative Example 2

[0077] Preparation of a Prussian blue analogue carbon-based electrode (nickel hexacyanoferrate (NiHCF)-carbon cloth electrode)

[0078] (1) Activation of carbon cloth substrate: The carbon cloth was immersed in acetone, ethanol, and deionized water successively and ultrasonically washed for 5 min. The cleaned carbon cloth was placed in a 3 M HNO3solution and reacted at 120 °C for 2 h. Finally, the carbon cloth was taken out, washed with deionized water, and dried at 60 °C overnight to obtain the activated carbon cloth substrate.

[0079] (2) Preparation of NiHCF powder: 100 mL of 0.10 M aqueous K3[Fe(CN)6]) and 0.20 M Ni(NO3)2·6H2O were simultaneously added dropwise into 40 mL of deionized water at a rate of 0.5 mL·min-1using a peristaltic pump. The mixture was left to stand overnight and then stirred magnetically for 10 min. Subsequently, the supernatant of the mixture was removed using a pipette. The precipitate was centrifuged at 5000 rpm for 10 min and repeated three times. Vacuum freeze-drying was performed at -76 °C for 10 h. Finally, the NiHCF was manually ground into powder using a mortar and pestle. -1 (2) Preparation of NiHCF powder: 100 mL of 0.10 M aqueous K3[Fe(CN)6]) and 0.20 M Ni(NO3)2·6H2O were simultaneously added dropwise into 40 mL of deionized water at a rate of 0.5 mL·min-1using a peristaltic pump. The mixture was left to stand overnight and then stirred magnetically for 10 min. Subsequently, the supernatant of the mixture was removed using a pipette. The precipitate was centrifuged at 5000 rpm for 10 min and repeated three times. Vacuum freeze-drying was performed at -76 °C for 10 h. Finally, the NiHCF was manually ground into powder using a mortar and pestle.

[0080] (3) 0.250 g NiHCF powder, 0.025 g polyvinyl fluoride and 0.025 g carbon black were ground into a mixed state in a mortar, and then 3.5 mL 1-methyl-2-pyrrolidone was added for dissolution. Under the irradiation of an infrared lamp, a drop-casting method was used to cast the solution on a 1 x 3 cm 2 After vacuum freeze-drying of 0.5 mL NiHCF slurry on carbon felt for 10 h, a NIHCF-carbon cloth electrode was obtained. In this electrode, the loading of the Prussian blue analogue (nickel-doped Prussian blue) on the carbon cloth substrate was 2.8 mg / cm 2 The morphology of the Prussian blue analogue (nickel-doped Prussian blue, NIHCF) loaded on the carbon cloth substrate was a rough particle agglomerate, and the particle size was 150-200 nm.

[0081] Application Example 1

[0082] Desalination experiment of a membrane capacitive deionization (MCDI) system based on a NiHCF-carbon cloth electrode

[0083] (1) Assembly of a membrane capacitive deionization main device: a membrane capacitive deionization main device was assembled in the order of a glass plate, a silica gel gasket, a titanium sheet current collector, a cathode material, a cation exchange membrane, a silica gel gasket, a plastic separator, a silica gel gasket, an anion exchange membrane, an anode, a titanium sheet current collector, a silica gel gasket, and a glass plate. The glass plate had a thickness of 10 mm and was provided with corresponding water inlets and outlets. The silica gel gasket and the plastic separator had a 1 x 5 cm 2 vacuum water channel in between, and were provided with small holes at the corresponding positions to achieve the purpose of salt water entering from the lower end, flowing through the electrode area, and then flowing out from the upper end.

[0084] (2) The Prussian blue analogue carbon-based electrode (NiHCF-carbon cloth) prepared in Example 1 was placed in the MCDI system as the cathode. The untreated carbon cloth material was used as the anode.

[0085] (3) Assembly of the overall device: salt solution, peristaltic pump, membrane capacitive deionization main device, portable conductivity meter, multimeter, direct current stabilized power supply, programmable electronic load. Under the condition that the power supply applied voltage to the main device, the peristaltic pump sent the salt solution into the main device from the water inlet at the lower end of the device, and the conductivity meter electrode was connected at the water outlet at the upper end. The multimeter measured the current change trend. The conductivity meter and the multimeter automatically recorded data every 10 s. When the salt solution conductivity value decreased and then returned to a stable state, the desalination stage ended. The applied voltage was 1.2 V, the salt solution flow rate was 0.4 mL / min, and the initial conductivity of the salt solution was 2000 μs / cm.

[0086] (4) Test results: during the membrane capacitive deionization process of this application example, the CV (cyclic voltammogram) of the NiHCF-carbon cloth electrode was as shown inFigure 3 As shown in Figure 3 It can be seen that, under different scan rates, Fe Ⅱ / Fe Ⅲ The redox peaks of the conversion show that there is ion insertion and deintercalation in the reaction process; the GCD (galvanostatic charge-discharge curve) diagram of the NiHCF-carbon cloth electrode is as shown in Figure 4 As shown in Figure 4 It can be seen that the curve has a large charge-discharge platform, indicating that there is ion insertion and deintercalation in the operation process, which is consistent with the results of the CV curve reaction. The charging time and discharging time are basically equal, indicating that the redox performance of the electrode material is reversible. The conductivity and current test data are as shown in Figure 5 As shown in, (a) is the conductivity change diagram, and (b) is the current change diagram; as shown in (a), the conductivity is reduced to 1838 μs / cm in the effective removal time. The current efficiency calculated from (b) is 67.04%.

[0087] Application Example 2

[0088] The same as Application Example 1, the only difference is that the NiHCF-carbon felt electrode prepared in Example 2 is used instead of the NiHCF-carbon cloth electrode prepared in Example 1 as the cathode. The conductivity and current test data of this application example are as shown in Figure 6 As shown in, (a) is the conductivity change diagram, and (b) is the current change diagram; as shown in (a), the conductivity is reduced to 1872 μs / cm in the effective removal time. The current efficiency calculated from (b) is 83.57%.

[0089] Application Example 3

[0090] The same as Application Example 1, the only difference is that the NiHCF-carbon cloth electrode prepared in Example 3 is used instead of the NiHCF-carbon cloth electrode prepared in Example 1 as the cathode. The conductivity and current test data of this application example are as shown in Figure 7 As shown in, (a) is the conductivity change diagram, and (b) is the current change diagram; as shown in (a), the conductivity is reduced to 1828 μs / cm in the effective removal time. The current efficiency calculated from (b) is 78.33%.

[0091] Comparative Application Example 1

[0092] The same as Application Example 1, the only difference is that the electrode prepared in Comparative Example 1 is used instead of the NiHCF-carbon cloth electrode prepared in Example 1 as the cathode, and the initial conductivity of the salt solution is 1000 μs / cm. The conductivity and current test data of this comparative application example are as shown in Figure 8Figure 2 shows the conductivity and current test data of the comparative application example 1, wherein (a) is the conductivity change graph, and (b) is the current change graph; as can be seen from (a), within the effective removal time, the conductivity is reduced to a minimum of 944 μs / cm. The current efficiency calculated from (b) is 33.94%.

[0093] Comparative application example 2

[0094] The same as application example 1, except that the electrode prepared in comparative example 2 is used instead of the NiHCF-carbon cloth electrode prepared in example 1 as the cathode, and the initial conductivity of the salt solution is 1000 μs / cm. The conductivity and current test data of the comparative application example are shown in Figure 9 Figure 3, wherein (a) is the conductivity change graph, and (b) is the current change graph; as can be seen from (a), within the effective removal time, the conductivity is reduced to a minimum of 853 μs / cm. The current efficiency calculated from (b) is 51.04%.

[0095] Comparative application example 3

[0096] The same as application example 1, except that the untreated carbon cloth material is used instead of the NiHCF-carbon cloth electrode prepared in example 1 as the cathode. The conductivity and current test data of the comparative application example are shown in Figure 10 Figure 4, wherein (a) is the conductivity change graph, and (b) is the current change graph; as can be seen from (a), within the effective removal time, the conductivity is reduced to a minimum of 1985 μs / cm. The current efficiency calculated from (b) is 0.12%.

[0097] Comparative application example 4

[0098] The same as application example 1, except that the applied voltage is 1.0 V, the flow rate of the salt solution is 0.6 mL / min, and the initial conductivity of the salt solution is 500 μs / cm. The conductivity and current test data of the comparative application example are shown in Figure 11 Figure 5, wherein (a) is the conductivity change graph, and (b) is the current change graph; as can be seen from (a), within the effective removal time, the conductivity is reduced to a minimum of 440 μs / cm. The current efficiency calculated from (b) is 65.78%.

[0099] In addition, the stability test results of the NiHCF-carbon cloth electrode prepared in example 1 are shown in Figure 12 Figure 6, and it can be seen that the performance of the electrode after 20 cycles during 2000 cycles only slightly decreases compared to the first 20 cycles, indicating that the in-situ grown electrode has good cycle stability. Figure 12

[0100] ​The above described embodiments are only to illustrate the preferred modes of the present application, and are not intended to limit the scope of the present application. Any modification and improvement made by those skilled in the art to the technical solutions of the present application without departing from the design spirit of the present application shall fall within the protection scope of the present application as defined by the claims.

Claims

1. A Prussian blue analogue carbon-based electrode, characterized in that A carbon material is used as a substrate, and a Prussian blue analogue is in situ loaded on the carbon material substrate; the morphology of the Prussian blue analogue is a nanoparticle cluster with a particle size of 30-200 nm; the Prussian blue analogue is a transition metal-doped Prussian blue; The preparation method of the Prussian blue analogue carbon-based electrode comprises the following steps: in situ loading a Prussian blue analogue on a carbon material substrate through a one-step hydrothermal reaction to obtain the Prussian blue analogue carbon-based electrode; The in-situ loading of a Prussian blue analogue on a carbon material substrate through a one-step hydrothermal reaction comprises: activating the carbon material substrate, soaking the activated carbon material substrate in a potassium ferricyanide aqueous solution, then adding a transition metal salt solution and a carboxylic acid solution, and heating to perform a hydrothermal reaction to obtain the Prussian blue analogue carbon-based electrode.

2. The Prussian blue analogue carbon-based electrode according to claim 1, wherein The transition metal-doped Prussian blue is one of nickel-doped Prussian blue, magnesium-doped Prussian blue, copper-doped Prussian blue, cobalt-doped Prussian blue and zinc-doped Prussian blue.

3. The Prussian blue analogue carbon-based electrode according to claim 1, wherein The concentration of the potassium ferricyanide aqueous solution is 0.005-0.05M; the soaking time is 1-5h.

4. The Prussian blue analogue carbon-based electrode according to claim 1, wherein The transition metal salt solution is a nickel salt solution, a magnesium salt solution, a copper salt solution, a cobalt salt solution, or a zinc salt solution; the carboxylic acid solution is an aqueous solution of one or more of formic acid, acetic acid, propionic acid, and butyric acid; the concentrations of the transition metal salt solution and the carboxylic acid solution are the same as the concentration of the potassium ferricyanide aqueous solution; and the volume ratio of the potassium ferricyanide aqueous solution, the transition metal salt solution, and the carboxylic acid solution is 1:1.5-2.5:0.5-1.

5. The Prussian blue analogue carbon-based electrode according to claim 1, wherein The temperature of the hydrothermal reaction is 55-65° C., and the time is 5-8 hours.

6. The Prussian blue analogue carbon-based electrode according to claim 1, wherein Activating the carbon material substrate comprises: soaking the carbon material substrate in acetone, ethanol and water in sequence for ultrasonic treatment, drying, then heating and soaking in HNO3 solution, washing and drying.

7. The Prussian blue analogue carbon-based electrode according to claim 1, wherein The carbon material substrate is carbon cloth, carbon felt or carbon fiber.

8. Use of the Prussian blue analogue carbon-based electrode according to any one of claims 1 to 7 in capacitive deionization.

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