Preparation method of anti-fouling cathode with micro-nano layered structure

Abstract

The application belongs to the technical field of electrodes and discloses a preparation method of an anti-fouling cathode with a micro-nano layered structure. The steps are as follows: preparing a metal microarray; preparing a micro-nano layered structure; constructing an alkali-resistant protective layer on the micro-nano layered surface; and pouring an inert protective shell. The cathode prepared by the method can utilize the generated H2 micro-bubbles to migrate along the hydrophobic surface and gather into a bubble layer, preventing the cathode surface from contacting with H2O, Ca 2+ ‑ HCO3. Therefore, only the nano active sites serve as the anchor points of the scale crystals. When the scale crystals are stacked into chains, the stability between the scale crystals and the anchor points becomes weaker and weaker. Meanwhile, the continuous injection of H2 makes the bubble layer grow into large bubbles, which escape from the cathode surface under the action of buoyancy and break when migrating to the liquid surface. The vibration caused by the bubble breaking causes the scale crystal chains standing unstably on the active sites to automatically fall off. The application fundamentally solves the problem of cathode fouling and has great application potential in a wide range of fields.

Description

Technical Field

[0001] This invention belongs to the field of electrode technology and relates to a method for preparing an anti-fouling cathode with a micro-nano layered structure. Background Technology

[0002] Electrochemical technology has shown great potential in green energy and environmental protection, aligning perfectly with the "dual carbon" goal. This technology can utilize green energy for processes such as seawater hydrogen production, lithium extraction from salt lakes, and brackish water desalination, without the need for chemical reagents, demonstrating its environmental friendliness and high efficiency. However, one of the key technical challenges in its application is cathode scaling. Cathode scaling is caused by the electrolysis of water, which generates OH groups near the cathode surface. - Increased concentration, reacting with HCO3- in the water 3- Ca 2+ Mg 2+ The reaction produces insulating CaCO3 and Mg(OH)2, which precipitate on the cathode surface and gradually accumulate to form a hard deposit layer. Since calcium and magnesium ions are present in most real water, such as natural seawater which contains large amounts of calcium ions (0.4268 g / L) and magnesium ions (1.3307 g / L), as long as water decomposition (2H2O + e-) occurs at the cathode... - →2OH - The reaction (+H2↑) inevitably leads to the precipitation of scale crystals on the cathode surface, making cathode scaling unavoidable in actual water electrochemical reaction processes. Therefore, this inherent scaling phenomenon is hindering the application of electrochemical technology in real-world water environments.

[0003] Currently, there are few reports, both domestically and internationally, on preventing cathode scaling. The reference "Directseawater electrolysis by adjusting the local reaction environment of a catalyst" reports the introduction of a Lewis acid layer on the cathode surface to capture OH-. - This prevents the solution pH from rising, thus avoiding scale formation in the solution. However, the Lewis acid layer will attract OH-. -Surface trapping exacerbates scale nucleation on the electrode surface. Furthermore, the phase change membrane reported in the reference "Amembrane-based seawater electrolyser for hydrogen generation" converts seawater in situ into pure water for electrolysis via a phase change migration mechanism. However, the wetting problem of hydrophobic phase change membranes severely restricts the development of this method. Additionally, the reference "Efficientbubble / precipitatetrafficenablesstable seawater reduction electrocatalysisat industrial-level current densities" constructs a honeycomb 3D cathode to generate a large number of small-sized H2 bubbles to achieve continuous Mg repulsion. 2+ and Ca 2+ The method involves the deposition of scale crystals. However, this method uses natural wood to make electrodes, which is prone to breakage during carbonization, making it difficult to scale up. Furthermore, the reference "Visualization of crystal automatic exfoliation on an anti-scaling cathode with well-ordered hydrophobic microcones" discovered a mechanism for the automatic exfoliation of scale crystals using copper nanotipples highly dispersed on an inert surface. However, the alkali-corrosion properties of copper cause the nanotipples to detach after 8 hours of use, thus losing their anti-scaling function, rendering this electrode impractical.

[0004] The methods described above have made some contributions to the research on cathode anti-scaling, but they still do not solve this problem. Clearly, to completely solve this problem, a new type of cathode capable of automatically removing scale crystals must be developed. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing an anti-fouling cathode with a micro-nano layered structure.

[0006] The technical solution of the present invention:

[0007] A method for preparing an anti-fouling cathode with a micro / nano layered structure, comprising the following steps:

[0008] (1) Preparation of metal microarray structures: Preparation of Cl-containing - and OH - The mixed solution was used as the electrolyte. The metal wire bundle was fixed in the electrolyte and anodized for 1-300 min under constant temperature and constant voltage conditions of 1-99℃. Then it was rinsed and ready for use.

[0009] (2) Preparation of micro / nano layered structures: Using a solution of nickel salt, iron salt, cobalt salt, crystal plane protectant, buffer, and surfactant as the electrolyte, a constant current density of 1-200 mA / cm² was maintained under constant temperature conditions of 1-99℃. 2 The reaction time is 1-300 min, which enables the fabrication of nanostructures on microarray structures, resulting in materials with micro-nano hierarchical structures.

[0010] (3) Constructing an alkali-resistant protective layer: The material with a micro-nano layered structure is subjected to constant temperature conditions of 1-99℃, using OH... - A solution with a concentration of 0.05-20 mol / L was used as the electrolyte. After activation by 1-50,000 repeated cyclic voltammetric scans within a potential range of 1-20 V vs RHE, an alkaline corrosion-resistant micro-nano layered structure material was obtained.

[0011] (4) Preparation of inert protective shell: The alkali-resistant micro-nano layered structure material is placed vertically in the mold, a release agent is added, and then an inert slurry made of inert reagent, curing agent and binder is poured into the mold. It is then heat-cured at 50-450℃ for 1-300 min in an inert atmosphere to finally obtain the micro-nano layered anti-scaling electrode.

[0012] In step (1), Cl - and OH - The mass ratio is 2-40:1-30.

[0013] In step (1), the materials of the metal wire bundle include, but are not limited to, stainless steel, iron, copper, titanium, nickel, silver, platinum, etc.

[0014] In step (1), the metal wire bundle is placed vertically, and the length of the metal wire bundle immersed in the electrolyte accounts for 0.1%-20% of the total length. If the immersion length of the metal wire bundle is too short, the part below the liquid surface will not fall off due to gravity, while if the immersion length is too long, the current density at the liquid surface will be too low to etch the metal wire.

[0015] In step (1), the voltage for anodizing is related to the cross-sectional area of ​​the metal wire bundle by 0.1-50 V / cm². 2 If the voltage is too low, the metal wire cannot be etched; if it is too high, the metal wire will be over-etched and lose its microstructure.

[0016] In step (2), the mass ratio of nickel salt, iron salt, cobalt salt, crystal surface protectant, buffer and surfactant is 1-40:0.1-15:0.1-15:1-20:0.01-10:0.005-5.

[0017] In step (2), nickel salts include, but are not limited to, nickel chloride, nickel sulfate, nickel nitrate, and nickel sulfamate. Iron salts include, but are not limited to, ferrous chloride, ferrous sulfate, and ferrous nitrate. Cobalt salts include, but are not limited to, cobalt chloride, cobalt sulfate, cobalt nitrate, and cobalt carbonate. Crystal surface protectants include, but are not limited to, sodium chloride, calcium chloride, ammonium chloride, sodium citrate, and sodium dihydrogen phosphate. Buffers include, but are not limited to, boric acid and potassium hydroxide. Surfactants include, but are not limited to, sodium dodecyl sulfate and sodium dodecyl sulfonate.

[0018] In step (2), the microarray structure size is greater than 2μm, and the morphology includes but is not limited to cone, column, flower, needle, sphere, etc. The nanostructure size is less than 800nm, and the morphology includes but is not limited to cone, column, flower, needle, sphere, etc.

[0019] In step (4), the volume ratio of the release agent to the volume of the mold used for casting is 1%-15%. The volume of the release agent determines the degree of exposure of the micro-nano layered structure. If the volume of the release agent is too low, the micro-nano layered structure will be covered by an inert protective shell, while if it is too high, the distance between the micro-nano layered structure and the inert surface will be too large, which not only increases the size of the crystal nucleation sites, but also weakens the protective effect of the bubble layer.

[0020] In step (4), the mass ratio of inert reagent, curing agent and binder is 1-79:1-12:20-89.

[0021] In step (4), the inert reagent includes, but is not limited to, polytetrafluoroethylene, dodecyl mercaptan, and perfluorodecyltrimethoxysilane. The binder includes, but is not limited to, epoxy resin, polydimethylsiloxane, and acrylic resin. The curing agent includes, but is not limited to, vinyl-terminated polydimethylsiloxane, organic acid anhydrides, imidazoles, and modified amines.

[0022] The beneficial effects of this invention: The anti-fouling cathode with a micro-nano layered structure of this invention achieves the dispersion of active sites on an inert surface. This structure allows the generated H2 microbubbles to migrate along the inert surface and aggregate into a bubble layer, preventing the cathode surface from contacting H2O and Ca. 2+ HCO3 -Contact. This causes scale crystals to grow in chains on smaller active sites. Subsequently, the vibration generated by the enlargement and rupture of H2 bubbles causes the scale crystal chains standing on the active sites to automatically detach. This process repeats to achieve a dynamic equilibrium of automatic scale crystal detachment. In addition, the micro-nano layered structure can not only further reduce the size of scale nucleation sites, but also increase the density and dispersion of active sites. And through self-activation, the surface of the microcone array has the function of alkali corrosion resistance, effectively solving the problem of short life of active sites in microcone arrays. At the same time, the cast inert shell has high mechanical strength and chemical stability, effectively solving the problem of short life of inert surfaces. In summary, this invention is expected to fundamentally solve the problem of cathode scaling and further promote the development of electrochemical technology. Attached Figure Description

[0023] Figure 1 This is a flowchart of the preparation process of the present invention.

[0024] Figure 2 This is a partial scanning electron microscope image of the microarray structure.

[0025] Figure 3 This is a scanning electron microscope image of a micro / nano layered structure.

[0026] Figure 4 This is a physical image of an anti-fouling electrode with a micro-nano layered structure.

[0027] Figure 5 This is a scanning electron microscope image of a material without a microarray structure.

[0028] Figure 6 This is a scanning electron microscope image of a material without a nanostructure.

[0029] Figure 7 This is a graph showing the mass increment and homogeneous nucleation rate of the anti-scaling electrode during 154 hours of operation. Detailed Implementation

[0030] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and technical solutions.

[0031] Example 1

[0032] A method for preparing an anti-fouling electrode with a micro / nano layered structure is as follows:

[0033] (1) Nickel wire was used as the substrate. A mixed solution of sodium chloride and potassium hydroxide in a mass ratio of 2:30 was prepared as the electrolyte. A wire with a cross-sectional area of ​​1 cm² was used. 2 One end of a nickel wire bundle (20%) was immersed in the electrolyte and anodized for 5 minutes at a constant temperature of 45°C and a constant voltage of 25V, followed by rinsing with water. A partial scanning electron microscope image of the metal microarray structure is shown below. Figure 2 As shown.

[0034] (2) Electrodeposition was carried out in a two-electrode electrochemical system. The mass ratio of nickel sulfate, ferrous sulfate, cobalt sulfate, ammonium chloride, boric acid, and sodium dodecyl sulfate in the electrodeposition solution was 8:3:3:2:4.5:0.005. The electrodeposition temperature was 35℃, and the current density was 5 mA / cm². 2 Electrodeposition was performed for 300 minutes. After deposition, the sample was removed from the electrolyte, thoroughly rinsed with water and ethanol, and stored in anhydrous ethanol. Scanning electron microscopy images of the micro / nano layered structure are shown below. Figure 3 As shown.

[0035] (3) The electrodeposited material was activated by 50,000 repeated cyclic voltammetric scans at 45°C with 0.05 mol / L sodium hydroxide aqueous solution as electrolyte in a potential range of 19-20 V vs RHE. The material was then cleaned with water and set aside for use.

[0036] (4) The micro-nano layered metal material was vertically placed in an 8 mL mold, and then 0.08 mL of release agent was added. An inert slurry composed of polytetrafluoroethylene, vinyl-terminated polydimethylsiloxane, and polydimethylsiloxane in a mass ratio of 55:5:40 was then poured into the mold. The mixture was then thermosetting at 160 °C for 120 min under an argon atmosphere to obtain the micro-nano layered anti-scaling electrode. The actual anti-scaling electrode is shown in [image / image / description]. Figure 4 .

[0037] Example 2

[0038] (1) Stainless steel wire was used as the substrate. A mixed solution of potassium chloride and sodium hydroxide at a mass ratio of 40:1 was prepared as the electrolyte. A wire with a cross-sectional area of ​​100 cm² was used. 2 One end of a stainless steel wire bundle is immersed in an electrolyte and anodized for 300 minutes at a constant temperature of 35°C and a constant voltage of 10V. Then it is rinsed with water and ready for use.

[0039] (2) Electrodeposition was carried out in a two-electrode electrochemical system. The mass ratio of nickel chloride, ferrous chloride, cobalt chloride, sodium citrate, boric acid, and sodium dodecyl sulfonate in the electrodeposition solution was 40:0.1:15:20:10:5. The electrodeposition temperature was 85℃, and the current density was 150 mA / cm². 2 Electrodeposition for 3 minutes. After deposition, remove the sample from the electrolyte, rinse thoroughly with water and ethanol, and store in anhydrous ethanol.

[0040] (3) The electrodeposited material was activated by 20 cycles of cyclic voltammetry scans at 75°C with 20 mol / L potassium hydroxide aqueous solution as electrolyte in a potential range of 1-5 V vs RHE. The material was then cleaned with water and set aside for use.

[0041] (4) The micro-nano layered metal material is placed vertically in a mold with a volume of 720mL, and then 108mL of release agent is added. Then, an inert slurry made of dodecanethiol, modified amine and epoxy resin in a mass ratio of 1:12:87 is poured into the mold and heat-cured at 50℃ for 10min under nitrogen atmosphere to finally obtain the micro-nano layered anti-scaling electrode.

[0042] Example 3

[0043] (1) Titanium metal wire was used as the substrate. A mixed solution of sodium chloride and potassium hydroxide in a mass ratio of 2:30 was prepared as the electrolyte. A wire with a cross-sectional area of ​​0.5 cm² was used. 2 One end of a titanium wire bundle is immersed in an electrolyte and anodized for 1 minute at a constant temperature of 1°C and a constant voltage of 25V. It is then rinsed with water and ready for use.

[0044] (2) Electrodeposition was carried out in a two-electrode electrochemical system. The mass ratio of nickel nitrate, ferrous nitrate, cobalt nitrate, sodium chloride, potassium hydroxide, and sodium dodecyl sulfate in the electrodeposition solution was 15:15:0.1:20:0.01:5. The electrodeposition temperature was 99℃, and the current density was 200 mA / cm². 2 Electrodeposition for 1 minute. After deposition, remove the sample from the electrolyte, rinse thoroughly with water and ethanol, and store in anhydrous ethanol.

[0045] (3) The electrodeposited material was activated by 50 repeated cyclic voltammetric scans at 99°C with 0.1 mol / L sodium hydroxide aqueous solution as electrolyte in a potential range of 2-5 V vs RHE, and then cleaned with water for later use.

[0046] (4) The micro-nano layered metal material is placed vertically in a mold with a volume of 8 mL. Then, 0.4 mL of release agent is added. Then, an inert slurry made of polytetrafluoroethylene, vinyl-terminated polydimethylsiloxane and polydimethylsiloxane mixed in a mass ratio of 79:1:20 is poured into the mold. The mixture is then heat-cured at 450 °C for 30 min under an argon atmosphere to finally obtain the micro-nano layered anti-scaling electrode.

[0047] Example 4

[0048] (1) Silver wire was used as the substrate. All solutions in the experiment were prepared using analytical grade chemicals and ultrapure water. A mixed solution of potassium chloride and sodium hydroxide at a mass ratio of 10:5 was prepared as the electrolyte, and a cross-sectional area of ​​25 cm² was used. 2 One end of a silver metal wire bundle was immersed in an electrolyte and anodized for 3 minutes at a constant temperature of 99°C and a constant voltage of 5V. It was then rinsed with water and set aside for use.

[0049] (2) Electrodeposition was carried out in a two-electrode electrochemical system. The mass ratio of nickel sulfamate, ferrous chloride, cobalt carbonate, sodium dihydrogen phosphate, boric acid, and sodium dodecyl sulfate in the electrodeposition solution was 1:15:15:1:10:0.5. The electrodeposition temperature was 75℃, and the current density was 1 mA / cm². 2 Electrodeposition was performed for 300 minutes. After deposition, the sample was removed from the electrolyte, thoroughly rinsed with water and ethanol, and stored in anhydrous ethanol.

[0050] (3) The electrodeposited material was activated by repeated cyclic voltammetry scans at 75°C with 20 mol / L potassium hydroxide aqueous solution as electrolyte in a potential range of 5-15 V vs RHE. The material was then cleaned with water and set aside for use.

[0051] (4) The micro-nano layered metal material is placed vertically in a mold with a volume of 180mL, and then 9mL of release agent is added. Then, an inert slurry made of dodecanethiol, modified amine and epoxy resin in a mass ratio of 2:9:89 is poured into the mold and heat-cured at 150℃ for 1min under nitrogen atmosphere to finally obtain the micro-nano layered anti-scaling electrode.

[0052] Comparative Example 1

[0053] The constant voltage in step (1) of Example 1 was changed to 55V. The resulting scanning electron microscope image of the material's microstructure is shown below. Figure 5 As shown, due to excessive anodizing voltage, the metal wire bundle was over-etched, preventing the formation of a microarray structure.

[0054] Comparative Example 2

[0055] The current density in step (2) of Example 1 is changed to 300 mA / cm. 2 The scanning electron microscope (SEM) images of the material's microstructure are shown below. Figure 6 As shown, the electrodeposition current density is too high, preventing the formation of nanostructures.

[0056] Comparative Example 3

[0057] The amount of release agent in step (4) of Example 1 was changed to 0.05 mL. Because too little release agent was added, the entire metal part was covered by an inert protective shell, causing the material to lose its conductivity.

[0058] Comparative Example 4

[0059] The constant voltage in step (1) of Example 1 was changed to 0.05V. Because the anodizing voltage was too low, the metal wire bundle could not be etched and the microarray structure could not be formed.

[0060] Comparative Example 5

[0061] The current density in step (2) of Example 1 is changed to 0.5 mA / cm. 2 The electrodeposition current density was too low, preventing the formation of nanostructures.

[0062] Comparative Example 6

[0063] The volume of the release agent in step (4) of Example 1 was changed to 2 mL. Because too much release agent was added, the metal wire was exposed too much and could not be protected by the inert protective layer, so it did not have the ability to resist scaling.

[0064] Comparative Example 7

[0065] The thermosetting temperature in step (4) of Example 2 was changed to 460°C. Due to the excessively high heat treatment temperature, the inert protective shell was carbonized and lost its inert effect.

[0066] Comparative Example 8

[0067] The thermosetting temperature in step (4) of Example 2 was changed to 30°C. Because the heat treatment temperature was too low, the inert protective shell could not be cured, and therefore could not be formed.

[0068] Comparative Example 9

[0069] The length of the metal wire bundle immersed in the electrolyte in step (1) of Example 3 was changed to 25%. Because too much of the metal wire bundle was immersed in the electrolyte, the current density at the liquid surface was too low to etch the metal wire.

[0070] Comparative Example 10

[0071] The length of the metal wire bundle immersed in the electrolyte in step (1) of Example 3 is changed to 0.05%. Because the portion of the metal wire bundle immersed in the electrolyte is too small, the portion of the metal wire below the liquid surface will not fall off due to gravity, and therefore a microarray structure cannot be formed.

[0072] Long-term scale inhibition experiments were conducted in an electrochemical reaction tank. The anode and cathode used RuO2-IrO2-TiO2 / Ti mesh and the anti-scaling electrode obtained in Example 1, respectively. Mg was prepared... 2+ A 1 g / L solution was used as the electrolyte. A DC power supply of 100 mA / cm² was applied during the reaction. 2 The system was run at a constant current density for 154 hours. The experimental results are as follows: Figure 7 As shown, the anti-scaling electrode of the present invention maintained an anti-scaling rate of over 99% during a long-term operation of 154 hours, indicating that the present invention not only has excellent anti-scaling effect but also has the advantage of long service life.

Claims

1. A method for preparing an anti-fouling cathode with a micro / nano layered structure, characterized in that, The steps are as follows: (1) Preparation of metal microarray structure: Prepare a solution containing Cl - and OH - The mixed solution was used as the electrolyte. The metal wire bundle was fixed in the electrolyte and anodized for 1-300 min under constant temperature and constant voltage conditions of 1-99℃. Then it was rinsed and ready for use. (2) Preparation of micro / nano layered structures: Using a solution of nickel salt, iron salt, cobalt salt, crystal plane protectant, buffer, and surfactant as the electrolyte, a constant current density of 1-200 mA / cm² was maintained under constant temperature conditions of 1-99℃. 2 The reaction time is 1-300 min, which enables the fabrication of nanostructures on microarray structures, resulting in materials with micro-nano hierarchical structures. (3) Constructing an alkali-resistant protective layer: The material with a micro-nano layered structure is subjected to constant temperature conditions of 1-99℃, using OH... - A solution with a concentration of 0.05-20 mol / L was used as the electrolyte. After activation by 1-50,000 repeated cyclic voltammetric scans within a potential range of 1-20 V vs RHE, an alkaline corrosion-resistant micro-nano layered structure material was obtained. (4) Preparation of inert protective shell: The alkali-resistant micro-nano layered structure material is placed vertically in the mold, a release agent is added, and then an inert slurry made of inert reagent, curing agent and binder is poured into the mold. It is then heat-cured at 50-450℃ for 1-300 min in an inert atmosphere to finally obtain the micro-nano layered anti-scaling electrode.

2. The method for preparing an anti-fouling cathode with a micro-nano layered structure according to claim 1, characterized in that, In step (1), Cl - and OH - The mass ratio is 2-40:1-30.

3. The method for preparing an anti-fouling cathode with a micro-nano layered structure according to claim 1, characterized in that, In step (1), the metal wire bundle is made of stainless steel, iron, copper, titanium, nickel, silver, or platinum. The metal wire bundle is placed vertically, and the length of the metal wire bundle immersed in the electrolyte accounts for 0.1%-20% of the total length.

4. The method for preparing an anti-fouling cathode with a micro-nano layered structure according to claim 1, characterized in that, In step (1), the voltage for anodizing is related to the cross-sectional area of ​​the metal wire bundle by 0.1-50 V / cm. 2 .

5. The method for preparing an anti-fouling cathode with a micro-nano layered structure according to claim 1, characterized in that, In step (2), the mass ratio of nickel salt, iron salt, cobalt salt, crystal surface protectant, buffer and surfactant is 1-40:0.1-15:0.1-15:1-20:0.01-10:0.005-5.

6. The method for preparing an anti-fouling cathode with a micro-nano layered structure according to claim 1, characterized in that, In step (2), the nickel salts include nickel chloride, nickel sulfate, nickel nitrate, and nickel aminosulfonate; the iron salts include ferrous chloride, ferrous sulfate, and ferrous nitrate; the cobalt salts include cobalt chloride, cobalt sulfate, cobalt nitrate, and cobalt carbonate; the crystal surface protectants include sodium chloride, calcium chloride, ammonium chloride, sodium citrate, and sodium dihydrogen phosphate; the buffers include boric acid and potassium hydroxide; and the surfactants include sodium dodecyl sulfate and sodium dodecyl sulfonate.

7. The method for preparing an anti-fouling cathode with a micro-nano layered structure according to claim 1, characterized in that, In step (2), the microarray structure has a size greater than 2 μm and a morphology of cone, column, flower, needle, or sphere; the nanostructure has a size less than 800 nm and a morphology of cone, column, flower, needle, or sphere.

8. The method for preparing an anti-fouling cathode with a micro-nano layered structure according to claim 1, characterized in that, In step (4), the volume ratio of the release agent to the volume of the mold used for casting is 1%-15%.

9. The method for preparing an anti-fouling cathode with a micro-nano layered structure according to claim 1, characterized in that, In step (4), the mass ratio of inert reagent, curing agent and binder is 1-79:1-12:20-89.

10. The method for preparing an anti-fouling cathode with a micro-nano layered structure according to claim 1, characterized in that, In step (4), the inert reagents are polytetrafluoroethylene, dodecanethiol, and perfluorodecyltrimethoxysilane; the binders are epoxy resin, polydimethylsiloxane, and acrylic resin; and the curing agents are vinyl-terminated polydimethylsiloxane, organic acid anhydrides, imidazoles, and modified amines.

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