Electro-adsorption desalting electrode coating material and preparation method of coated electrode

Abstract

The invention relates to the technical field of water treatment, in particular to an electro-adsorption desalting electrode coating material and a preparation method of a coated electrode, and solves the problems of small specific capacitance, poor chemical stability, poor durability and poor adsorption capacity of an electrode caused by an existing coating material.The preparation method comprises the steps that 1, walnut shells are ground into powder and subjected to pyrolysis treatment to form walnut shell carbon; (2) mixing KOH, (NH4) 2HPO4 and the walnut shell carbon, drying, pyrolyzing, washing with deionized water, drying again and grinding to prepare nitrogen / phosphorus modified walnut shell carbon; and (3) stirring and mixing deionized water, MoSe2 and the nitrogen / phosphorus modified walnut shell charcoal, adding absolute ethyl alcohol, stirring, then adding hydrazine hydrate, continuously stirring, transferring the mixed solution to a hydrothermal reaction kettle, carrying out hydrothermal reaction, pouring supernatant liquid out of a cooled substance after the reaction is finished, collecting a black precipitate at the bottom, washing the black precipitate with absolute ethyl alcohol and deionized water respectively, and drying to obtain the nitrogen / phosphorus modified walnut shell charcoal. And finally, drying to obtain the nitrogen / phosphorus modified walnut shell carbon and molybdenum selenide loaded electro-adsorption desalting electrode coating material.

Description

Technical Field

[0001] The present invention relates to the technical field of water treatment, in particular to an electro-adsorption desalination electrode coating material and a preparation method of the coated electrode. Background Art

[0002] Biochar, a functional carbon material obtained by pyrolysis of biomass under anoxic or low-oxygen conditions, has become one of the research hotspots in the field of water treatment due to its advantages such as wide raw material sources, low cost, and green environmental protection. Biochar has a developed pore structure and a high specific surface area, as well as good chemical stability, which makes it show good application potential in electrosorption deionization technology. As an emerging water treatment method, electrosorption deionization technology has the advantages of low energy consumption, simple operation, no chemical agent addition, and reversible regeneration. It can effectively remove soluble salts and some organic pollutants in water. Applying biochar materials to electrosorption electrodes is expected to prepare new electrode materials with high adsorption capacity, high selectivity, corrosion resistance and recyclability. It is widely used in drinking water desalination, industrial wastewater treatment and seawater pretreatment, and has good practical application prospects.

[0003] Chinese Patent Publication No. CN119390068A discloses a walnut shell graded porous activated biochar and its preparation method and application. The biochar is activated by KOH. When this biochar activated only by KOH is used to coat an electrosorption desalination electrode, the problems mainly include the following aspects: 1. The prepared electrode has a smaller specific capacitance Although KOH activation can increase the pore structure of biochar to a certain extent, the micropores formed are mostly narrow and lack sufficient synergistic effects between mesopores and macropores. This results in limited mass transfer during ion transport and energy storage, making it difficult to fully utilize its energy storage capacity, resulting in low specific capacitance and limiting its application in the process of electrical adsorption desalination. 2. Insufficient chemical stability and durability of electrodes The biochar electrodes obtained by KOH activation are susceptible to chemical corrosion or structural collapse, especially under high voltage or multiple adsorption and desorption cycles. Their electrical conductivity and structural integrity are prone to decline, seriously affecting their service life and stability. They are difficult to meet the long-term service performance requirements of materials in actual engineering applications, and their adsorption capacity is not good enough. 3. Adsorption capacity performance is not ideal KOH activation mainly relies on physical pores to provide adsorption sites and lacks functional surface groups, resulting in low selectivity and affinity for ions. In addition, the limited number of active sites on the electrode surface has not significantly improved the binding ability for salt ions, thus restricting the further improvement of its adsorption capacity and failing to meet the needs of efficient desalination. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide an electro-adsorption desalination electrode coating material and a method for preparing the coated electrode, so as to overcome the problems of low specific capacitance, insufficient chemical stability and durability, and poor adsorption capacity of the adsorption electrode caused by existing coating materials.

[0005] The technical solution adopted by the present invention to solve the technical problem is: a method for preparing an electro-adsorption desalination electrode coating material, comprising the following steps: (1) Preparation of walnut shell charcoal: Grind the walnut shell into powder and pyrolyze it to produce walnut shell charcoal; (2) Nitrogen / phosphorus co-doping modification treatment: KOH, (NH4)2HPO4 and walnut shell charcoal were mixed, dried, pyrolyzed, rinsed with deionized water, dried again and ground to prepare nitrogen / phosphorus modified walnut shell charcoal; (3) Molybdenum selenide loading treatment: Deionized water, MoSe2 and nitrogen / phosphorus modified walnut shell charcoal are stirred and mixed, anhydrous ethanol is added, and hydrazine hydrate is added after stirring. The mixed solution after continued stirring is transferred to a hydrothermal reactor for hydrothermal reaction. After the reaction is completed, the cooled material is poured out of the upper liquid, and the black precipitate at the bottom is collected and rinsed with anhydrous ethanol and deionized water respectively. Finally, it is dried to form a nitrogen / phosphorus modified walnut shell charcoal loaded with molybdenum selenide electrosorption desalination electrode coating material.

[0006] Specifically, process (1) is a method for preparing walnut shell charcoal from walnut shell powder, comprising the steps of sieving the walnut shell powder to 90-130 mesh, washing the walnut shell powder with 0.05-0.2 mol / L H2SO4 and deionized water respectively to remove impurities in the walnut shell powder, drying the washed walnut shell powder, heating the walnut shell powder to 450-550°C at a heating rate of 5°C / min in a tube furnace under a nitrogen environment, and then maintaining the temperature for 1-3 h to pyrolyze the walnut shell powder into fresh biochar, washing the fresh biochar again with 0.05-0.2 mol / L H2SO4 to remove salts present in the biochar, rinsing the fresh biochar with deionized water until the pH is 7, and drying the fresh biochar to obtain walnut shell charcoal.

[0007] Specifically, in process (1), the drying temperature of walnut shell powder is 60~80℃ and the drying time is 8~15h; the time of washing fresh biochar with 0.05~0.2mol / L H2SO4 is 6~15h; the drying temperature of biochar after washing with deionized water is 60~80℃ and the drying time is 8~15h.

[0008] Specifically, in process (2), the mixture of KOH, (NH4)2HPO4 and walnut shell charcoal was stirred for 0.5-3 h, ultrasonically treated for 0.2-1 h and then dried. The pyrolysis was continued under nitrogen at 600-900 °C for 0.5-3 h. After cooling, the product was rinsed with deionized water until the pH was 7, and then dried and ground.

[0009] Specifically, in process (2), the mixture is dried at 50-80°C before pyrolysis until the mass no longer decreases; the drying temperature of the product after rinsing with deionized water is 50-80°C and the drying time is 8-15h.

[0010] Specifically, in process (2), the mass ratio of KOH, (NH4)2HPO4 and walnut shell charcoal is 2:2:0.5~2.

[0011] Specifically, in process (3), the mass ratio of deionized water, MoSe2 and nitrogen / phosphorus modified walnut shell charcoal is 15:0.0025~0.015:1, and the mass ratio of hydrazine hydrate and nitrogen / phosphorus modified walnut shell charcoal is 2~8:1.

[0012] Specifically, in process (3), the temperature of the hydrothermal reaction is 160~200℃.

[0013] The coating material prepared by the above process is used to make an electrosorption desalination coating electrode, which is to disperse the coating material, acetylene black and polyvinylidene fluoride in N,N-dimethylacetamide to form a slurry, which is then coated on an electrode substrate and dried to form an electrosorption desalination coating electrode.

[0014] Specifically, the mass ratio of the coating material, acetylene black, polyvinylidene fluoride and N,N-dimethylacetamide is 8:1:1:40-80.

[0015] The mechanism of the present invention is to improve the electrode performance by N / P co-doping and MoSe2 composite synergistically, using (NH4)2HPO4 as the source of nitrogen and phosphorus, releasing active nitrogen and phosphorus species during the carbonization process, and embedding them into the carbon skeleton in the form of graphitic nitrogen, pyrrolic nitrogen, PC, PO, etc., forming rich active sites and adjusting the electronic structure of the carbon material, significantly improving its conductivity and hydrophilicity. Subsequently, MoSe2 is introduced into the surface of modified biochar, and its porous structure and surface N / P functional groups are utilized to achieve in-situ loading of MoSe2 under hydrothermal conditions. In this process, the addition of hydrazine hydrate can effectively control its particle size and dispersibility, avoid agglomeration, enhance interfacial bonding strength and electrocatalytic activity, and the synergistic effect of N / P co-doping and MoSe2 loading gives the composite material a higher specific surface area, electron transport capacity and number of active centers, thereby effectively improving its comprehensive performance in adsorption or electrochemical applications.

[0016] The beneficial effects of the present invention are as follows: the present invention uses walnut shell as a base material, prepares nitrogen / phosphorus modified walnut shell carbon by nitrogen / phosphorus co-doping, and then loads MoSe2 on the surface to prepare nitrogen / phosphorus modified walnut shell carbon and loaded with molybdenum selenide electrosorption desalination electrode coating material; First, nitrogen / phosphorus introduction was achieved through KOH activation and (NH4)2HPO4 co-doping, constructing an adsorption substrate with a large specific surface area and strong charge storage capacity, thereby enhancing electrode activity; Second, in situ growth of MoSe2 on the electrode surface to construct a loaded composite structure to further improve conductivity and adsorption capacity; Third, by systematically optimizing key parameters such as MoSe2 loading and reaction temperature, its corrosion resistance and stability were enhanced; 4. Compared with traditional carbon materials, walnut shell resources are inexpensive, widely available, and environmentally friendly, with extremely high resource utilization value and potential for large-scale industrial promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a flow chart for preparing the electrode coating material of the present invention; Figure 2 is a comparison chart of NaCl adsorption capacity of Examples 2, 4 and 5 at different reaction temperatures; Figure 3 is a comparison of the NaCl adsorption capacity of Examples 1, 2, and 3 at different MoSe2 loadings; Figure 4 2 is a comparison chart of the NaCl adsorption capacity of the electrodes of the comparative example, embodiment 2 and embodiment 5; Figure 5 This is a diagram of multiple electrosorption cycle experiments in Example 2. DETAILED DESCRIPTION

[0018] The present invention further illustrates the technical features with the following embodiments in conjunction with the accompanying drawings, but the protection scope of the present invention is not limited to the following embodiments.

[0019] Example 1 The walnut shells were ground into powder using a grinder, sieved to about 110 mesh, washed with 0.1M H2SO4 and deionized water for 24 hours to remove impurities in the biochar, and placed in a forced air drying oven at 70°C for 12 hours. The powder was heated to 500°C at a heating rate of 5°C / min in a tube furnace under N2 gas flow and then pyrolyzed for 2 hours. The fresh biochar was washed again with 0.1M H2SO4 for 12 hours until no bubbles were observed to remove the salt in the biochar, and then rinsed with deionized water until the pH was 7. The powder was placed in a forced air drying oven at 70°C for 12 hours to make walnut shell charcoal for later use.

[0020] KOH was used as an activating agent, (NH4)2HPO4 was added and mixed with walnut shell charcoal, the mixture was stirred for 2 h, then ultrasonically treated for 0.5 h, and dried at 60 °C until there was no mass loss. The products were kept at 800 °C in N2 for 1 h, cooled, and rinsed with deionized water until the pH was 7. Finally, they were dried at 60 °C for 12 h and ground to prepare nitrogen / phosphorus modified walnut shell charcoal (labeled as NPWSC) for use.

[0021] In a 100 mL beaker, 30 mL (30 g) of deionized water was added, followed by 10 mg of MoSe2 and 2 g of NPWSC. After thorough stirring, 15.78 g of anhydrous ethanol was added and stirring continued for 10 min. 10.32 g of hydrazine hydrate was added and stirring continued for 30 min. Finally, the mixed solution was transferred to a 100 mL hydrothermal reactor lined with polytetrafluoroethylene, completely sealed, and placed in a blast drying oven for reaction at 180 ° C for 24 h. After the oven was cooled naturally to room temperature, the reactor was opened, the upper liquid was poured out, the black precipitate at the bottom was collected, and the mixture was rinsed repeatedly with anhydrous ethanol and deionized water. Finally, the mixture was placed in a blast drying oven at 60 ° C for use. The dried product was a nitrogen / phosphorus modified walnut shell carbon and loaded with molybdenum selenide electrosorption desalination electrode coating material (marked as MoSe2 / NPWSC); the amount of MoSe2 used (10 mg) and the hydrothermal reaction temperature (180 ° C) were added to the mark, and the electrode material obtained in this Example 1 was recorded as MoSe2 / NPWSC. 10-180 .

[0022] MoSe2 / NPWSC 10-180 , acetylene black and polyvinylidene fluoride are dispersed in N,N-dimethylacetamide to form a slurry which is coated on an electrode substrate and dried to form an electro-adsorption desalination coating electrode. The amounts of coating material, acetylene black, polyvinylidene fluoride and N,N-dimethylacetamide are 0.48g, 0.06g, 0.06g and 3.75g respectively.

[0023] Example 2 The preparation process of walnut shell charcoal is the same as that in Example 1.

[0024] The preparation process of nitrogen / phosphorus modified walnut shell charcoal (NPWSC) was the same as that in Example 1.

[0025] In a 100 mL beaker, 30 mL (30 g) of deionized water was added, followed by 20 mg of MoSe2 and 2 g of NPWSC. After thorough stirring, 15.78 g of anhydrous ethanol was added and stirring continued for 10 min. 10.32 g of hydrazine hydrate was added and stirring continued for 30 min. Finally, the mixed solution was transferred to a 100 mL hydrothermal reactor lined with polytetrafluoroethylene, which was completely sealed and placed in a blast drying oven for reaction at 180°C for 24 h. After the oven cooled naturally to room temperature, the reactor was opened, the upper layer of liquid was poured out, and the black precipitate at the bottom was collected. The product was rinsed repeatedly with anhydrous ethanol and deionized water, and finally dried in a blast drying oven at 60°C for later use. The dried product was MoSe2 / NPWSC. The amount of MoSe2 used (20 mg) and the hydrothermal reaction temperature (180°C) were added to the mark. Then, the electrode material obtained in Example 2 was recorded as MoSe2 / NPWSC. 20-180 .

[0026] The preparation process of the coated electrode is the same as that in Example 1.

[0027] Example 3 The preparation process of walnut shell charcoal is the same as that in Example 1.

[0028] The preparation process of nitrogen / phosphorus modified walnut shell charcoal (NPWSC) was the same as that in Example 1.

[0029] In a 100 mL beaker, 30 mL (30 g) of deionized water was added, followed by 30 mg of the synthesized MoSe2 and 2 g of NPWSC. After thorough stirring, 15.78 g of anhydrous ethanol was added and stirring continued for 10 min. 10.32 g of hydrazine hydrate was added and stirring continued for 30 min. Finally, the mixed solution was transferred to a 100 mL hydrothermal reactor lined with polytetrafluoroethylene, which was completely sealed and placed in a blast drying oven for reaction at 180° C. for 24 h. After the oven was cooled naturally to room temperature, the reactor was opened, the upper layer of liquid was poured out, and the black precipitate at the bottom was collected. The product was rinsed repeatedly with anhydrous ethanol and deionized water, and finally dried in a blast drying oven at 60° C. for later use. The dried product was MoSe2 / NPWSC. The amount of MoSe2 used (30 mg) and the hydrothermal reaction temperature (180° C.) were added to the mark. The electrode material obtained in Example 3 was recorded as MoSe2 / NPWSC. 30-180 .

[0030] The preparation process of the coated electrode is the same as that in Example 1.

[0031] Example 4 The preparation process of walnut shell charcoal is the same as that in Example 1.

[0032] The preparation process of nitrogen / phosphorus modified walnut shell charcoal (NPWSC) was the same as that in Example 1.

[0033] In a 100 mL beaker, 30 mL of deionized water was added, followed by 20 mg of the synthesized MoSe2 and 2 g of NPWSC. After thorough stirring, 15.78 g of anhydrous ethanol was added and stirring continued for 10 min. 10.32 g of hydrazine hydrate was added and stirring continued for 30 min. Finally, the mixed solution was transferred to a 100 mL polytetrafluoroethylene-lined hydrothermal reactor, which was completely sealed and placed in a blast drying oven for reaction at 160° C. for 24 h. After the oven was cooled naturally to room temperature, the reactor was opened, the upper layer of liquid was poured out, and the black precipitate at the bottom was collected. The product was rinsed repeatedly with anhydrous ethanol and deionized water, and finally dried in a blast drying oven at 60° C. for later use. The dried product was MoSe2 / NPWSC. The amount of MoSe2 used (20 mg) and the hydrothermal reaction temperature (160° C.) were added to the mark. The electrode material obtained in Example 4 was recorded as MoSe2 / NPWSC. 20-160 .

[0034] The preparation process of the coated electrode is the same as that in Example 1.

[0035] Example 5 The preparation process of walnut shell charcoal is the same as that in Example 1.

[0036] The preparation process of nitrogen / phosphorus modified walnut shell charcoal (NPWSC) was the same as that in Example 1.

[0037] In a 100 mL beaker, 30 mL of deionized water was added, followed by 20 mg of the synthesized MoSe2 and 2 g of NPWSC. After thorough stirring, 15.78 g of anhydrous ethanol was added and stirring continued for 10 min. 10.32 g of hydrazine hydrate was added and stirring continued for 30 min. Finally, the mixed solution was transferred to a 100 mL hydrothermal reactor lined with polytetrafluoroethylene, which was completely sealed and placed in a blast drying oven for reaction at 200 ° C for 24 h. After the oven was cooled naturally to room temperature, the reactor was opened, the upper liquid was poured out, and the black precipitate at the bottom was collected. The product was rinsed repeatedly with anhydrous ethanol and deionized water, and finally dried in a blast drying oven at 60 ° C for use. The dried product is MoSe2 / NPWSC. The amount of MoSe2 used (20 mg) and the hydrothermal reaction temperature (200 ° C) were added to the mark. Then, the electrode material obtained in Example 5 is recorded as MoSe2 / NPWSC. 20-200 .

[0038] The preparation process of the coated electrode is the same as that in Example 1.

[0039] Comparative Example The preparation process of the walnut shell carbon of the comparative example is the same as that of Example 1. In the preparation process of the nitrogen / phosphorus modified walnut shell carbon (NPWSC) of the comparative example, (NH4)2HPO4 is not used, the comparative example does not have nitrogen / phosphorus co-doping modification content, and the comparative example does not load MoSe2. The coating material of the comparative example is marked as WSC, and the preparation process of the comparative example coated electrode is the same as that of Example 1.

[0040] The performance of the electrode obtained in the above example was tested under the following test conditions: adsorption treatment of brine with a salt concentration of 500 mg / L, an inlet flow rate of 10 mL / min, a voltage of 1.2 V, and an electrode plate spacing of 2 mm.

[0041] The test results are: 1. The adsorption capacities of Examples 1, 2 and 3 with the same hydrothermal reaction temperature of 180°C but MoSe2 dosages of 10 mg, 20 mg and 30 mg are as follows: Figure 3 : The adsorption capacity of the electrode in Example 1 is 30.31 mg / g; The adsorption capacity of the electrode in Example 2 is 32.26 mg / g; The adsorption capacity of the electrode in Example 3 is 28.72 mg / g.

[0042] Second, the adsorption capacities of Examples 2, 4 and 5 with the same amount of 20 mg of MoSe2 but the hydrothermal reaction temperatures of 160°C, 180°C and 200°C are as follows: Figure 2 : The adsorption capacity of the electrode in Example 2 is 32.26 mg / g; The adsorption capacity of the electrode in Example 4 is 29.82 mg / g; The adsorption capacity of the electrode in Example 5 is 26.92 mg / g.

[0043] 3. Comparison was performed by adding comparative examples. The objects of comparison were Example 2 and Example 5. The adsorption capacities of the three were as follows: Figure 4 : The adsorption capacity of the comparative electrode is 15.71 mg / g: The adsorption capacity of the electrode in Example 2 is 32.26 mg / g; The adsorption capacity of the electrode in Example 5 is 26.92 mg / g.

[0044] From the above test results, the adsorption capacity of the electrode in Example 2 is good. Further tests on the adsorption capacity retention are carried out. The test results are as follows: Figure 5 As shown in the figure, under the conditions of salt concentration of 500 mg / L, water flow rate of 10 mL / min, voltage of 1.2 V, and plate spacing controlled at 2 mm, the adsorption capacity decreased slightly after 50 cycle experiments, and the adsorption capacity retention rate was about 94% after 50 cycles.

[0045] Still based on the electrode adsorption capacity of the above comparative example and all embodiments, the adsorption capacity test results of the walnut shell electrodes prepared by the embodiments and comparative examples showing the degree of performance improvement are prepared in Table 1 below.

[0046] Table 1: Preparation conditions of materials in Examples and Comparative Examples and test results of the prepared materials' properties

[0047] As can be seen from the above table, with the change of reaction temperature and MoSe2 mass, the performance of MoSe2 / NPWSC prepared by the present invention is significantly improved. The adsorption capacity of MoSe2 / NPWSC prepared in Examples 1 to 5 of the present invention is compared with the WSC material activated by simple KOH in the comparative example. The adsorption capacity of the comparative example is only 15.70 mg / g. After co-doping modification of MoSe2 and (NH4)2HPO4, the adsorption capacity of Example 5, which has the worst adsorption performance among the prepared materials, is also increased to 1.71 times that of the WSC material, while the adsorption capacity of Example 2, which has the best adsorption performance, is increased to 2.05 times that of the WSC material.

[0048] The above examples all show that as the walnut shell carbon material is modified, the adsorption capacity increases. 20-180 The electrode has the best desalination effect, and the adsorption effect is good after multiple cycles of use, with good cycle stability.

[0049] With the above-described preferred embodiments of the present invention as a guide, and with reference to the above description, relevant personnel are fully capable of making various changes and modifications without departing from the technical scope of this invention. The technical scope of this invention is not limited to the contents of the specification and must be determined according to the scope of the claims.

Claims

1. A method for preparing an electro-adsorption desalination electrode coating material, characterized by: The process is as follows: (1) Preparation of walnut shell charcoal: grinding walnut shell into powder and pyrolyzing it to produce walnut shell charcoal; (2) Nitrogen / phosphorus co-doping modification treatment: KOH, (NH4)2HPO4 and walnut shell charcoal are mixed, dried, pyrolyzed, rinsed with deionized water, dried again and ground to prepare nitrogen / phosphorus modified walnut shell charcoal; (3) Molybdenum selenide loading treatment: deionized water, MoSe2 and nitrogen / phosphorus modified walnut shell carbon are stirred and mixed, anhydrous ethanol is added, and hydrazine hydrate is added after stirring. The mixed solution after continued stirring is transferred to a hydrothermal reactor for hydrothermal reaction. After the reaction is completed, the upper liquid is poured out of the cooled material, and the black precipitate at the bottom is collected and rinsed with anhydrous ethanol and deionized water respectively. Finally, it is dried to form a nitrogen / phosphorus modified walnut shell carbon and loaded with molybdenum selenide electrosorption desalination electrode coating material.

2. The method for preparing the electro-adsorption desalination electrode coating material according to claim 1, wherein: Process (1) The method for preparing walnut shell charcoal from walnut shell powder is as follows: sieve the walnut shell powder to 90-130 mesh, wash it with 0.05-0.2 mol / L H2SO4 and deionized water respectively to remove impurities in the walnut shell powder, dry the washed walnut shell powder, place the walnut shell powder in a tube furnace under a nitrogen environment at a heating rate of 5°C / min to 450-550°C, and then keep the temperature for 1-3 hours to pyrolyze it into fresh biochar, wash the fresh biochar again with 0.05-0.2 mol / L H2SO4 to remove salts present in the biochar, and then rinse it with deionized water until the pH is 7, and then dry it to obtain walnut shell charcoal.

3. The method for preparing the electro-adsorption desalination electrode coating material according to claim 2, wherein: In process (1), the drying temperature of walnut shell powder is 60~80℃ and the drying time is 8~15h; the time of washing fresh biochar with 0.05~0.2mol / L H2SO4 is 6~15h; the drying temperature of biochar after washing with deionized water is 60~80℃ and the drying time is 8~15h.

4. The method for preparing the electro-adsorption desalination electrode coating material according to claim 1, wherein: In process (2), the mixture of KOH, (NH4)2HPO4 and walnut shell charcoal is stirred for 0.5~3h, ultrasonically treated for 0.2~1h and then dried. The pyrolysis is continued in nitrogen at 600~900℃ for 0.5~3h. After cooling, the product is rinsed with deionized water until the pH is 7, and then dried and ground.

5. The method for preparing the electro-adsorption desalination electrode coating material according to claim 4, wherein: In process (2), the mixture is dried at 50-80°C before pyrolysis until the mass no longer decreases; the product after rinsing with deionized water is dried at a temperature of 50-80°C and for a time of 8-15 hours.

6. The method for preparing the electro-adsorption desalination electrode coating material according to any one of claims 1, 4 or 5, characterized in that: In process (2), the mass ratio of KOH, (NH4)2HPO4 and walnut shell charcoal is 2:2:0.5~2.

7. The method for preparing the electro-adsorption desalination electrode coating material according to claim 1, wherein: In process (3), the mass ratio of deionized water, MoSe2 and nitrogen / phosphorus modified walnut shell carbon is 15:0.0025~0.015:1, and the mass ratio of hydrazine hydrate and nitrogen / phosphorus modified walnut shell carbon is 2~8:

1.

8. The method for preparing the electro-adsorption desalination electrode coating material according to claim 1, wherein: In process (3), the temperature of the hydrothermal reaction is 160~200℃.

9. A method for preparing an electro-adsorption desalination coating electrode, characterized by: The coating material prepared by the preparation method of the electrosorption desalination electrode coating material according to any one of claims 1 to 8, acetylene black and polyvinylidene fluoride are dispersed in N,N-dimethylacetamide to form a slurry which is coated on an electrode substrate and dried to prepare an electrosorption desalination coating electrode.

10. The method for preparing the electrosorption desalination coating electrode according to claim 9, wherein: The mass ratio of the coating material, acetylene black, polyvinylidene fluoride and N,N-dimethylacetamide is 8:1:1:60-80.

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