A method of preparing an anti-fouling cathode with an alloy microstructure

Abstract

This invention belongs to the field of electrode fabrication technology and discloses a method for preparing an anti-fouling cathode with an alloy microstructure. The steps include: constructing an alloy microstructure on a substrate surface; constructing an alkali-resistant protective layer on the surface of the microstructure; and coating an inert coating on the surface of the material with the microstructure. This cathode can utilize 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. Therefore, only the tips of the microstructures serve as anchor points for scale crystals. As scale crystals stack into chains, the stability between them and the anchor points weakens. Simultaneously, continuous H2 injection causes the bubble layer to grow into large bubbles, which escape from the cathode surface under buoyancy and burst as they migrate towards the liquid surface. The vibrations generated by the bursting bubbles cause the unstable scale crystal chains on the microstructure to automatically detach. Furthermore, the alkali-resistant protective layer formed after the self-activation of the alloy microstructure greatly improves the lifespan of the anti-scaling cathode in alkaline environments.

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 an alloy microstructure. Background Technology

[0002] Electrochemical technology has shown great potential in the fields of green energy and environmental protection. 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 added chemical reagents, demonstrating its environmentally friendly and efficient characteristics. However, one of the key technical challenges in the application of this technology 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 - 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 most real water contains calcium and magnesium ions—for example, natural seawater 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 "Direct seawater 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 "A membrane-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 "Efficient bubble / precipitate traffic-enablesstable seawater reduction electrocatalysis at 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, it is necessary to develop a new type of cathode capable of automatically removing scale crystals. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing an anti-fouling cathode with an alloy microstructure.

[0006] The technical solution of the present invention:

[0007] A method for preparing an anti-fouling cathode with an alloy microstructure, comprising the following steps:

[0008] (1) Construction of alloy microstructure: First, the metal substrate is pretreated, and then, under constant temperature conditions of 1-99℃, an electrolyte solution of metal salt, crystal plane protectant, buffer and surfactant is used, and the current density is 1-200mA / cm. 2 The reaction time is 1-300 min to obtain a material with an alloy microstructure;

[0009] (2) Construction of a microstructured alkali-resistant protective layer: The material with the alloy microstructure 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 microstructure was obtained.

[0010] (3) Construction of inert coating: Prepare an inert coating containing inert reagent, dispersant and binder, apply the inert coating evenly to the alkali corrosion resistant microstructure, and heat cure at 50-450℃ for 1-300min in an inert atmosphere to obtain an anti-scaling cathode with alloy microstructure.

[0011] In step (1), the metal substrate includes, but is not limited to, stainless steel, iron, copper, titanium, nickel, etc.

[0012] In step (1), the morphology of the microstructure includes, but is not limited to, cone-shaped, columnar, flower-shaped, needle-shaped, etc.

[0013] In step (1), the mass ratio of metal salt, crystal surface protectant, buffer and surfactant is 0.1-50:1-20:0.01-10:0.005-5.

[0014] In step (1), the metal salts include, but are not limited to, nickel chloride, nickel sulfate, nickel nitrate, nickel sulfamate, ferrous chloride, ferrous sulfate, cobalt chloride, cobalt sulfate, manganese chloride, manganese sulfate, chromium chloride, chromium nitrate, potassium molybdate, sodium molybdate, copper sulfate, copper chloride, stannous chloride, palladium nitrate, titanium oxysulfate, sodium hydroxyplatinate, etc. Crystal surface protectants include, but are not limited to, sodium chloride, calcium chloride, ammonium chloride, sodium citrate, sodium dihydrogen phosphate, etc. Buffers include, but are not limited to, boric acid, potassium hydroxide, etc. Surfactants include, but are not limited to, sodium dodecyl sulfate, sodium dodecyl sulfonate, etc.

[0015] In step (3), the mass ratio of inert reagent, dispersant and binder is 0.5-50:0.01-10:0.1-50.

[0016] In step (3), the inert reagent includes, but is not limited to, polytetrafluoroethylene, dodecathiol, and perfluorodecyltrimethoxysilane. The dispersant includes, but is not limited to, xanthan gum and polyvinyl butyral. The binder includes, but is not limited to, epoxy resin, polydimethylsiloxane, and acrylic resin.

[0017] The beneficial effects of this invention: This invention constructs a method for preparing an anti-scaling cathode capable of automatically removing scale crystals. A method for preparing alloy microstructures by electrochemical deposition is established, while simultaneously coating the surface with an inert coating, allowing the microstructures to disperse on the inert coating. 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 at 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 detachment. Furthermore, the self-activation of the microstructure surface creates a protective layer resistant to alkali corrosion, effectively solving the problem of short lifespan of the microstructure active sites. Simultaneously, by adjusting the composition of the inert coating, the adhesion between the inert surface and the metal substrate is enhanced, solving the problem of short inert coating lifespan. This invention is expected to solve the common problem of cathode scaling in practical applications of electrochemical technology, requiring no chemical additions, no additional operating steps, and no interruption of the electrochemical reaction, offering numerous advantages such as low carbon footprint, simplicity, and high efficiency. Attached Figure Description

[0018] Figure 1 This is a flowchart of the preparation process of the present invention.

[0019] Figure 2 This is a physical image of an anti-scaling electrode with a nickel, iron, and cobalt alloy microstructure.

[0020] Figure 3 This is a scanning electron microscope image of an anti-fouling electrode with a nickel, iron, and cobalt alloy microstructure.

[0021] Figure 4 These are scanning electron microscope images of the microstructure of nickel, manganese, and tin alloys.

[0022] Figure 5 These are scanning electron microscope images of the microstructure of nickel, copper, and chromium alloys.

[0023] Figure 6 It is a scanning electron microscope image of a material surface without microstructure.

[0024] Figure 7 This is a scanning electron microscope image of an anti-scaling electrode with a nickel, iron, and cobalt alloy microstructure after an alkali resistance test. Detailed Implementation

[0025] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and technical solutions.

[0026] Example 1

[0027] A method for preparing an anti-scaling electrode with an alloy microstructure is as follows:

[0028] (1) A 40-mesh commercial nickel mesh was used as the substrate. All solutions in the experiment were prepared using analytical grade chemicals and ultrapure water. Before electrodeposition, the nickel mesh was first cleaned to remove surface contaminants and oxides. 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 8:3:3:1:10:0.005. 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.

[0029] (2) 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.

[0030] (3) An inert coating was prepared in butyl acetate with a mass fraction ratio of dodecanethiol, polyvinyl butyral, and epoxy resin of 0.5:0.01:10. This inert coating was then uniformly applied to the material containing the alloy microstructure using a dip-coating method and heat-cured at 50°C for 300 min to obtain an anti-scaling electrode. The actual anti-scaling electrode is shown in [Image of the prepared electrode]. Figure 2 Microscopic morphology of electrode surface is shown Figure 3 .

[0031] Example 2

[0032] (1) A 40-mesh commercial stainless steel mesh was used as the substrate. All solutions in the experiment were prepared using analytical grade chemicals and ultrapure water. Before electrodeposition, the stainless steel mesh was first cleaned to remove surface contaminants and oxides. Electrodeposition was carried out in a two-electrode electrochemical system. The mass ratio of nickel chloride, manganese chloride, stannous chloride, sodium citrate, potassium hydroxide, and sodium dodecyl sulfate in the electrodeposition solution was 50:0.1:10:20:0.01:5. The electrodeposition temperature was 99℃, and the current density was 200 mA / cm². 2 Electrodeposition was performed for 1 minute. After deposition, the sample was removed from the electrolyte, thoroughly rinsed with water and ethanol, and stored in anhydrous ethanol. Scanning electron micrographs of the obtained nickel-manganese-tin alloy microstructure are shown below. Figure 4 As shown.

[0033] (2) The electrodeposited material was activated by cyclic voltammetry scan at 99°C with 20 mol / L sodium hydroxide aqueous solution as electrolyte in a potential range of 1-10 V vs RHE, and then cleaned with water for later use.

[0034] (3) Prepare an inert coating with a mass fraction ratio of polytetrafluoroethylene, xanthan gum and polydimethylsiloxane of 50:10:0.1 in water. Apply the inert coating evenly to the material containing the alloy microstructure by dip-coating and heat curing at 450℃ for 30 min to obtain an anti-scaling electrode.

[0035] Example 3

[0036] (1) A 40-mesh commercial titanium mesh was used as the substrate. All solutions in the experiment were prepared using analytical grade chemicals and ultrapure water. Before electrodeposition, the titanium mesh was first cleaned to remove surface contaminants and oxides. Electrodeposition was carried out in a two-electrode electrochemical system. The mass ratio of nickel sulfate, copper sulfate, chromium nitrate, sodium chloride, boric acid, and sodium dodecyl sulfate in the electrodeposition solution was 15:15:15:10:3:1. The electrodeposition temperature was 1℃, and the current density was 1 mA / cm². 2 Electrodeposition was performed for 200 minutes. After deposition, the sample was removed from the electrolyte, thoroughly rinsed with water and ethanol, and stored in anhydrous ethanol. Scanning electron micrographs of the obtained nickel, copper, and chromium alloy microstructures are shown below. Figure 5 As shown.

[0037] (2) The electrodeposited material was activated by 10,000 cyclic voltammetric scans at 1°C with 15 mol / L sodium hydroxide aqueous solution as electrolyte in a potential range of 5-15 V vs RHE, and then cleaned with water for later use.

[0038] (3) Prepare an inert coating in hexane with a mass fraction ratio of perfluorodecyltrimethoxysilane, polyvinyl butyral and polydimethylsiloxane of 1:5:50. Apply the inert coating evenly to the material containing the alloy microstructure by dip coating and heat cure at 120°C for 60 min to obtain an anti-scaling electrode.

[0039] Comparative Example 1

[0040] The current density in step (1) 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 was too high, preventing the formation of alloy microstructures during electrodeposition.

[0041] Comparative Example 2

[0042] The current density in step (1) of Example 1 is changed to 0.5 mA / cm. 2 The electrodeposition current density was too low, preventing the formation of alloy microstructures.

[0043] Comparative Example 3

[0044] The sodium hydroxide concentration in step (2) of Example 1 was changed to 25 mol / L. Due to the presence of OH in the solution... - Excessive concentration can cause the alloy microstructure deposited on the surface to be etched and destroyed during the reaction.

[0045] Comparative Example 4

[0046] The sodium hydroxide concentration in step (2) of Example 1 was changed to 0.01 mol / L. This is because the OH content in the solution... - If the concentration is too low, an alkali-resistant protective layer cannot be formed on the surface of the alloy microstructure.

[0047] Comparative Example 5

[0048] The heat treatment temperature in step (3) of Example 2 was changed to 460°C. Due to the excessively high heat treatment temperature, the inert coating was carbonized and lost its inert effect.

[0049] Comparative Example 6

[0050] The heat treatment temperature in step (3) of Example 2 was changed to 30°C. Because the heat treatment temperature was too low, the inert coating could not adhere to the surface of the alloy microstructure.

[0051] Comparative Example 7

[0052] The cyclic voltammetric scan potential in step (2) of Example 3 was changed to 0.1-0.9V vs RHE. Because the cyclic voltammetric scan potential was too small, the alkali corrosion resistant protective layer on the surface of the alloy microstructure could not be formed.

[0053] Comparative Example 8

[0054] The cyclic voltammetric scan potential in step (2) of Example 3 was changed to 21-25V vs RHE. Due to the excessively large cyclic voltammetric scan potential, the alloy microstructure was etched and destroyed.

[0055] The electrode alkali resistance test was conducted in an electrochemical reaction tank. The anode and cathode used RuO2-IrO2-TiO2 / Ti mesh and an anti-scaling electrode, respectively. A 1M potassium hydroxide solution was prepared as the electrolyte. The electrolyte was tested at 1 mA / cm². 2 The reaction was carried out at a constant current density for 120 h. The microstructure of the electrode surface after the reaction is as follows. Figure 7 As shown.

[0056] Electrode scale inhibition experiments were conducted in an electrochemical reaction tank. The anode and cathode used RuO2-IrO2-TiO2 / Ti mesh and anti-scaling electrodes, respectively. A solution containing 120 mg / L Ca was prepared. 2+ 360mg / L HCO3 - An aqueous solution was used as the electrolyte. A DC power supply of 1 mA / cm² was applied during the reaction.2 A constant current density was applied, and the reaction time was 1 hour. The experimental results are shown in Table 1:

[0057] Table 1. Performance Comparison of Metal Mesh Electrode and Anti-fouling Electrode

[0058]

[0059]

Claims

1. A method for preparing an anti-scaling cathode with an alloy microstructure, characterized in that, The steps are as follows: (1) Construction of alloy microstructure: First, the metal substrate is pretreated, and then under constant temperature conditions of 1-99 °C, an electrolyte solution of metal salt, crystal plane protectant, buffer and surfactant is used, and the current density is 1-200 mA / cm 2 The reaction time is 1-300 min to obtain a material with an alloy microstructure; (2) Construction of the microstructure alkali-resistant protective layer: The material with alloy microstructure is subjected to constant temperature conditions of 1-99 °C with 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 microstructure was obtained. (3) Construction of inert coating: Prepare an inert coating containing inert reagent, dispersant and binder, apply the inert coating evenly to the alkali corrosion resistant microstructure, and heat cure at 50-450 ℃ for 1-300 min in an inert atmosphere to obtain an anti-scaling cathode with alloy microstructure.

2. The method for preparing an anti-scaling cathode with an alloy microstructure according to claim 1, characterized in that, In step (1), the metal substrate is stainless steel, iron, copper, titanium, or nickel.

3. The method for preparing an anti-scaling cathode with an alloy microstructure according to claim 1, characterized in that, In step (1), the morphology of the microstructure is conical, columnar, flower-like, or needle-like.

4. The method for preparing an anti-scaling cathode with an alloy microstructure according to claim 1, characterized in that, In step (1), the mass ratio of metal salt, crystal surface protectant, buffer and surfactant is 0.1-50:1-20:0.01-10:0.005-5.

5. The method for preparing an anti-scaling cathode with an alloy microstructure according to claim 1, characterized in that, In step (1), the metal salts are nickel chloride, nickel sulfate, nickel nitrate, nickel aminosulfonate, ferrous chloride, ferrous sulfate, cobalt chloride, cobalt sulfate, manganese chloride, manganese sulfate, chromium chloride, chromium nitrate, potassium molybdate, sodium molybdate, copper sulfate, copper chloride, stannous chloride, and palladium nitrate; the crystal surface protectants are sodium chloride, calcium chloride, ammonium chloride, sodium citrate, and sodium dihydrogen phosphate; the buffers are boric acid and potassium hydroxide; and the surfactants are sodium dodecyl sulfate and sodium dodecyl sulfonate.

6. The method for preparing an anti-scaling cathode with an alloy microstructure according to claim 1, characterized in that, In step (3), the mass ratio of inert reagent, dispersant and binder is 0.5-50:0.01-10:0.1-50.

7. The method for preparing an anti-scaling cathode with an alloy microstructure according to claim 1, characterized in that, In step (3), the inert reagents are polytetrafluoroethylene, dodecathiol, and perfluorodecyltrimethoxysilane; the dispersants are xanthan gum and polyvinyl butyrate; and the binders are epoxy resin, polydimethylsiloxane, and acrylic resin.

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