Highly adherent electrochemical descaling porous iridium-based titanium anode and method for making same

Abstract

This invention provides a porous iridium-based titanium anode with high bonding strength for electrochemical descaling and its preparation method, relating to the field of electrochemical electrode material preparation technology. The aforementioned porous iridium-based titanium anode is constructed by sequentially preparing a TiO2-SnO2 composite layer, a SnO2-IrO2 composite transition layer, and an IrO2 glaze layer on the surface of a titanium substrate, and then constructing a porous iridium electrodeposition layer using a PS microsphere template method. The PS microsphere template method creates a highly ordered porous array, significantly improving the effective reaction area and ion diffusion efficiency of the electrode, directly translating into an excellent descaling rate. Furthermore, strong chemical bonds are formed between the various layers, endowing the anode with excellent stability. By controlling the electrolyte composition for preparing the iridium electrodeposition layer, uniform deposition of IrO2 within the pores can be ensured, giving the anode excellent electrochemical descaling performance.

Description

Technical Field

[0001] This invention relates to the field of electrochemical electrode material preparation technology, and in particular to a highly adhesive electrochemical descaling porous iridium-based titanium anode and its preparation method. Background Technology

[0002] Currently, electrochemical descaling technology is widely used in industrial circulating water treatment, seawater desalination, and other fields due to its advantages such as high efficiency and environmental friendliness. Its working principle involves an electrochemical reaction that creates a highly alkaline region on the cathode surface, causing calcium and magnesium ions in the water to precipitate as calcium carbonate, magnesium hydroxide, etc., thereby removing scale ions. Simultaneously, the anode surface can generate strong oxidizing substances or form a localized strong acid environment, playing a synergistic role in descaling and sterilization / algae removal. The descaling efficiency and operational stability of an electrochemical descaling system mainly depend on the coordinated operation of the anode, cathode, and power supply system.

[0003] Traditional anode materials (such as graphite and platinum electrodes) generally suffer from poor corrosion resistance or high cost. Iridium oxide (IrO2) coated titanium anodes, as representatives of size-stabilized anodes (DSA), possess excellent electrocatalytic activity and corrosion resistance, but existing iridium-tantalum (IrO2) coated anodes...

[0004] The anodic oxygen evolution overpotential of the Ta₂O₅ coating is relatively high, resulting in limited descaling activity. Furthermore, its thermal decomposition preparation process is cumbersome and energy-intensive, and the iridium loading is typically not less than 15 g / m². 2 This results in persistently high overall costs.

[0005] Electrodeposition has attracted much attention due to its advantages of mild conditions and controllable loading. Existing patents have used electrodeposition to prepare iridium oxide coatings, achieving preliminary control over the iridium loading. However, this method is still limited to flat or two-dimensional structures, resulting in limited electrode surface area and low mass transfer efficiency. While polystyrene (PS) microsphere templates can construct three-dimensional porous structures to significantly increase the surface area, their application in the preparation of electrochemical descaling anodes remains unexplored. More importantly, when hydrophobic PS microsphere templates are directly used for iridium oxide electrodeposition, the poor affinity between the microsphere surface and the inorganic coating easily leads to weak coating adhesion and easy detachment.

[0006] In view of this, it is necessary to design an improved high-bonding electrochemical descaling porous iridium-based titanium anode and its preparation method to solve the above problems. Summary of the Invention

[0007] The purpose of this invention is to provide a porous iridium-based titanium anode with high bonding strength for electrochemical descaling and its preparation method.

[0008] To achieve the above-mentioned objectives, in a first aspect, the present invention provides a method for preparing a highly adhesive electrochemical descaling porous iridium-based titanium anode, comprising the following steps:

[0009] S1. The pretreated titanium substrate is immersed in an electroplating solution containing stannous sulfate, and a TiO2-SnO2 composite layer is obtained on the surface of the titanium substrate by constant current electrodeposition and thermal oxidation treatment.

[0010] S2. Using a pyrolysis spraying method, a spraying liquid containing iridium salt and tin salt is sprayed onto the surface of the TiO2-SnO2 composite layer, and then subjected to thermal decomposition treatment to obtain a SnO2-IrO2 composite transition layer on the surface of the TiO2-SnO2 composite layer.

[0011] S3. An iridium precursor solution is loaded onto the surface of the titanium substrate containing the SnO2-IrO2 composite transition layer obtained in step S2 to ensure that the iridium precursor solution is fully coated on the surface of the titanium substrate. Then, after heat treatment, a dense and smooth IrO2 glaze layer is obtained on the surface of the SnO2-IrO2 composite transition layer.

[0012] S4. The titanium substrate containing the IrO2 glaze layer obtained in step S3 is immersed in the PS microsphere dispersion. An ordered monolayer template layer is assembled on the surface of the IrO2 glaze layer using the dip-coating method. Periodic electrodeposition is performed in the iridium electroplating solution. After removing the PS microsphere template layer, the porous iridium-based titanium anode is obtained through sintering.

[0013] Preferably, in step S4, the pH of the iridium plating solution is 10-10.5, and it contains iridium salt, potassium oxalate, polyethylene glycol, and sodium dodecyl sulfate; the concentration of iridium salt in the iridium plating solution is 2.5-5.0 g / L, the concentration of potassium oxalate is 3-6 g / L, the concentration of polyethylene glycol is 0.1-0.5 g / L with a molecular weight of 400-2000, and the concentration of sodium dodecyl sulfate is 0.05-0.2 g / L.

[0014] Preferably, in step S4, the scanning voltage range of the periodic electrodeposition is -0.6 V to 0.6 V, the scanning rate is 1-5 mV / s, and the number of cycles is 15-60.

[0015] Preferably, in step S3, the iridium precursor solution is obtained by dissolving chloroiridium acid in anhydrous ethanol, and the iridium concentration is 5-15 g / L.

[0016] Preferably, in step S2, the spraying liquid includes chloroiridium acid, tin chloride, isopropanol and n-butanol, wherein the iridium concentration is 3-8 g / L, the tin concentration is 5-10 g / L, and the volume ratio of isopropanol to n-butanol is 1:3; the pyrolysis spraying temperature is 400-500℃, and the number of spraying times is 5-10.

[0017] Preferably, in step S1, the process parameters for the constant current electrodeposition are as follows: current density of -5 to -10 mA / cm². 2 The deposition time is 15-30 min; the thermal oxidation treatment is performed at a temperature of 500℃ for 2 h.

[0018] Preferably, in step S4, the particle size of the PS microspheres is 200 nm-4 μm; the sintering temperature is 350-450℃, and the holding time is 2 h.

[0019] In a second aspect, the present invention provides an electrochemical descaling porous iridium-based titanium anode, comprising:

[0020] Titanium substrate;

[0021] The composite functional layer includes a TiO2-SnO2 composite layer, a SnO2-IrO2 composite transition layer, and an IrO2 glaze layer stacked sequentially, wherein the TiO2-SnO2 composite layer is tightly bonded to the titanium substrate.

[0022] The thickness of the TiO2-SnO2 composite layer is 1-5 μm, the thickness of the SnO2-IrO2 composite transition layer is 0.5-3 μm, and the thickness of the IrO2 glaze layer is 100-500 nm.

[0023] The pore structure of the iridium-based titanium anode has a specific surface area of ​​15-60 m². 2 / g, with an average pore diameter of 200 nm-4 μm and a porosity of 35-75%.

[0024] Thirdly, the present invention provides an application of a porous iridium-based titanium anode for electrochemical descaling, comprising the following steps:

[0025] The anode and cathode are immersed in the circulating cooling water to be treated, and the water is electrolyzed under a DC electric field. The anode is a porous iridium-based titanium anode.

[0026] The electrolysis process occurs at a current density of 1-10 mA / cm². 2 The process is carried out at a temperature of 20-40℃, and the circulating cooling water contains Ca. 2+ and HCO3 - .

[0027] Fourthly, the present invention provides an electrochemical descaling device, including an electrochemical descaling porous iridium-based titanium anode.

[0028] The beneficial effects of this invention are:

[0029] 1. The electrochemical descaling porous iridium-based titanium anode provided by the present invention is constructed by sequentially preparing a TiO2-SnO2 composite layer, a SnO2-IrO2 composite transition layer, and an IrO2 glaze layer on the surface of a titanium substrate, and then constructing an iridium electrodeposition layer (IrO2) with a porous structure by means of a PS microsphere template method. The TiO2-SnO2 composite layer ensures efficient electron transport between the titanium substrate and the upper catalyst layer, and effectively prevents passivation and corrosion of the titanium substrate. The SnO2-IrO2 composite transition layer further optimizes the electrochemical activity and thermal expansion matching of the electrode surface. The dense and smooth IrO2 glaze layer not only enhances the affinity with the PS template and ensures the complete construction of the porous structure, but also improves the erosion resistance and corrosion resistance of the electrode surface. The iridium electrodeposition layer can electrolytically release active oxygen species, forming a local strong oxidation and strong acid microenvironment on the electrode surface and inside the pores, thereby efficiently oxidizing, dissolving and stripping calcium and magnesium deposits attached to the electrode surface. With the synergistic effect of each layer, efficient descaling of water can be achieved.

[0030] 2. The preparation method proposed in this invention, through structural design and interface control, achieves several structural improvements. Structurally, the highly ordered porous array constructed using the PS microsphere template method not only increases the electrochemical active area several times over but also breaks mass transfer limitations through a unique pore structure, significantly enhancing ion diffusion efficiency and directly translating into excellent descaling rates. At the interface, a step-by-step construction strategy is adopted, forming a strongly coupled system of mechanical interlocking and chemical bonding from the in-situ grown TiO2-SnO2 composite layer to the SnO2-IrO2 composite transition layer and the surface gel glaze and IrO2 layer. This completely solves the problem of easy cracking and peeling of traditional coatings, giving the electrode an ultra-long lifespan. In terms of process, addressing the deposition difficulties within the porous structure, the technical bottleneck of uneven deposition within the pores is overcome by introducing specific additives and optimizing the periodic pulse electrodeposition parameters. Attached Figure Description

[0031] Figure 1 This is a flowchart illustrating the preparation process of the electrochemical descaling porous iridium-based titanium anode proposed in this invention.

[0032] Figure 2 The images show SEM images of the electrochemically descaling porous iridium-based titanium anode prepared in Example 1 of this invention before and after template removal.

[0033] Figure 3 The descaling rate and enhanced lifespan of the electrochemically descaling porous iridium-based titanium anodes prepared in Example 1 and Comparative Examples 1 to 4 of this invention are shown. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0035] It should also be noted that, in order to avoid obscuring the present invention with unnecessary details, only the structures and / or processing steps closely related to the present invention are shown in the accompanying drawings, while other details that are not closely related to the present invention are omitted.

[0036] Additionally, it should be noted that the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0037] On one hand, the present invention provides a highly adhesive electrochemical descaling porous iridium-based titanium anode, comprising:

[0038] Titanium substrate;

[0039] The composite functional layer comprises a TiO2-SnO2 composite layer, a SnO2-IrO2 composite transition layer, and an IrO2 glaze layer stacked sequentially. The TiO2-SnO2 composite layer is tightly bonded to the titanium substrate. The thickness of the TiO2-SnO2 composite layer is 1-5 μm, the thickness of the SnO2-IrO2 composite transition layer is 0.5-3 μm, and the thickness of the IrO2 glaze layer is 100-500 nm.

[0040] The specific surface area of ​​the pore structure of porous iridium-based titanium anodes is 15-60 m². 2 / g, with an average pore diameter of 200 nm-4 μm and a porosity of 35-75%.

[0041] On the other hand, please see Figure 1 As shown, the present invention also provides a method for preparing the above-mentioned electrochemical descaling porous iridium-based titanium anode, comprising the following steps:

[0042] S1. The pretreated titanium substrate is immersed in an electroplating solution containing stannous sulfate, and a TiO2-SnO2 composite layer is obtained on the surface of the titanium substrate by constant current electrodeposition and thermal oxidation treatment.

[0043] S2. Using a pyrolysis spraying method, a spraying liquid containing iridium salt and tin salt is sprayed onto the surface of the TiO2-SnO2 composite layer, and then subjected to thermal decomposition treatment to obtain a SnO2-IrO2 composite transition layer on the surface of the TiO2-SnO2 composite layer.

[0044] S3. An iridium precursor solution is loaded onto the surface of the titanium substrate containing the SnO2-IrO2 composite transition layer obtained in step S2 to ensure that the iridium precursor solution is fully coated on the surface of the titanium substrate. Then, after heat treatment, a dense and smooth IrO2 glaze layer is obtained on the surface of the SnO2-IrO2 composite transition layer.

[0045] S4. The titanium substrate containing the IrO2 glaze layer obtained in step S3 is immersed in the PS microsphere dispersion. An ordered monolayer template layer is assembled on the surface of the IrO2 glaze layer using the dip-coating method. Periodic electrodeposition is performed in the iridium electroplating solution with a scanning potential range of -0.6 to 0.6 V, a scanning rate of 5 mV / s, a cycle period of 30 laps, and a deposition temperature of 25℃. After removing the PS microsphere template layer, the substrate is sintered to obtain a porous iridium-based titanium anode.

[0046] In some embodiments, in step S1, the pretreatment of the titanium substrate is carried out according to the following steps: the titanium substrate is successively degreased by alkaline washing, sanded, polished in a mixed aqueous solution of 1 wt.% hydrofluoric acid and 3 wt.% nitric acid, and then anodized in an activation solution. The process parameters for the anodizing treatment are as follows: electrolysis voltage 20-30 V, electrolysis temperature 40-45℃, electrolysis time 2-3 h, and the activation solution is a mixed solution containing 5-8 mg / L ammonium fluoride and 0.3-0.5 wt.% hydrofluoric acid.

[0047] In some embodiments, in step S1, the electroplating solution is obtained by dissolving stannous sulfate in deionized water, and its concentration is 20-40 g / L.

[0048] In some embodiments, in step S1, the temperature of the thermal oxidation treatment is 500°C and the time is 2 hours.

[0049] In some embodiments, in step S1, the process parameters for constant current electrodeposition are as follows: current density of -5 to -10 mA / cm². 2 The deposition time is 15-30 min.

[0050] In some embodiments, in step S2, the spraying solution includes chloroiridium acid, tin chloride, isopropanol, and n-butanol. Based on the total volume of the spraying solution, the iridium concentration is 3-8 g / L, the tin concentration is 5-10 g / L, and isopropanol and n-butanol are used as solvents in a volume ratio of 1:3. The pyrolysis spraying temperature is 400-500°C, and the number of spraying passes is 5-10.

[0051] In some embodiments, in step S2, the thermal decomposition treatment is carried out at 200-300°C for 0.5-1 h.

[0052] In some embodiments, in step S3, the iridium precursor solution is obtained by dissolving chloroiridium acid in anhydrous ethanol, and the iridium concentration is 5-15 g / L (calculated as iridium). Here, "calculated as iridium" means that the mass concentration is calculated based on the mass of iridium metal element Ir in the solution, and the unit is g / L. It does not include ligands, chloride ions or water of crystallization in the precursor.

[0053] In some embodiments, in step S3, the loading of the iridium precursor solution onto the titanium substrate surface can be achieved by dip-coating or coating. If coating is used, the coating is applied 1-3 times.

[0054] In some embodiments, in step S4, the particle size of the PS microspheres is 200 nm-4 μm, and the amount used is 0.5-1 mL, which can be selected according to the descaling requirements.

[0055] In some embodiments, in step S4, the pH of the iridium plating solution is 10-10.5, and in addition to the main salt iridium salt and potassium oxalate, polyethylene glycol and sodium dodecyl sulfate are added. The concentration of iridium salt in the iridium plating solution is 2.5-5.0 g / L, the concentration of potassium oxalate is 3-6 g / L, the concentration of polyethylene glycol is 0.1-0.5 g / L, the molecular weight is 400-2000, and the concentration of sodium dodecyl sulfate is 0.05-0.2 g / L. Preferably, the concentration of iridium salt is 3.5 g / L and the concentration of potassium oxalate is 5 g / L.

[0056] In the above technical solution, in the iridium electrodeposition system with pH=10-10.5, potassium oxalate, as a complexing agent, effectively delays the rapid discharge of iridium ions on the cathode surface, increases cathode polarization, and promotes uniform nucleation and refinement of iridium grains within the micropores, fundamentally improving the density of the initial deposition layer. Based on this, polyethylene glycol (PEG) with a specific molecular weight (400-2000), through its strong adsorption and steric hindrance effect on the cathode surface, further suppresses abnormal protrusions deep within the micropores caused by diffusion limitation and induces uniform grain growth. Simultaneously, sodium dodecyl sulfate, as an anionic surfactant, significantly reduces the surface tension of the plating solution on the complex micropore walls, eliminates the adhesion of hydrogen bubbles at the bottom of blind holes, and ensures full exposure of active sites on the cathode surface. The synergistic effect of these components within the confined space of the micropores effectively overcomes the defects of uneven deposition in traditional electroplating, thereby achieving uniform and dense iridium layer growth within the template micropores.

[0057] In some embodiments, in step S4, the scanning voltage range for periodic electrodeposition is -0.6 V to 0.6 V (relative to a mercury-mercury oxide electrode), the scanning rate is 1-5 mV / s, and the number of cycles is 15-60. Preferably, the number of cycles is 30.

[0058] Furthermore, the present invention also provides a method for applying the above-mentioned porous iridium-based titanium anode in electrochemical descaling, comprising the following steps:

[0059] A porous iridium-based titanium anode is used as the anode, and the cathode is immersed in the circulating cooling water to be treated. The water is electrolyzed under a DC electric field.

[0060] The electrolysis process occurs at a current density of 1-10 mA / cm².2 The process is carried out at a temperature of 20-40℃, and the circulating cooling water contains Ca. 2+ and HCO3 - The distance between the cathode and anode plates can be 5 cm.

[0061] In some embodiments, in step S4, the sintering temperature is 350-450°C and the holding time is 2 h.

[0062] The following specific embodiments further illustrate the high-bonding electrochemical descaling porous iridium-based titanium anode and its preparation method proposed in this invention:

[0063] Example 1

[0064] This embodiment provides a method for preparing an electrochemically descaling porous iridium-based titanium anode, which includes the following steps:

[0065] S1. Select TA2 industrial pure titanium sheet (referring to Grade II industrial pure titanium sheet conforming to GB / T 3620.1 standard, with a titanium content ≥99.2%, length × width × height = 1cm × 2cm × 1mm) as the substrate. After alkaline washing to remove oil and sanding, polish in a mixed aqueous solution of 1 wt.% hydrofluoric acid and 3 wt.% nitric acid. Then, anodize in an activation solution containing 6 mg / L ammonium fluoride and 0.4 wt.% hydrofluoric acid at a constant voltage of 20 V and a temperature of 45℃ for 2.5h to complete the pretreatment of the substrate.

[0066] The pretreated titanium substrate was placed in a plating solution containing 30 g / L stannous sulfate (antimony-free) at a concentration of -8 mA / cm². 2 The current density constant current electrodeposition was carried out for 20 min, followed by thermal oxidation in a muffle furnace at 500℃ for 2 h to obtain a TiO2-SnO2 composite intermediate layer.

[0067] S2. A pyrolysis spraying method is used to spray a coating liquid onto the surface of the TiO2-SnO2 composite intermediate layer. After repeated spraying 8 times, the layer is thermally decomposed at 450℃ for 1 h, thus obtaining a SnO2-IrO2 composite transition layer on the surface of the TiO2-SnO2 composite intermediate layer. The coating liquid is obtained by dissolving iridium salt and tin salt in n-butanol, wherein the iridium concentration is 5 g / L and the tin concentration is 8 g / L.

[0068] S3. The substrate containing the SnO2-IrO2 composite transition layer from step S2 is immersed in an iridium precursor solution using the dip-pull method and pulled at a constant speed of 0.5 mm / s. Then, it is heat-treated in a muffle furnace at 250℃ for 0.5 h to form a dense and smooth IrO2 glaze layer. The iridium precursor solution is obtained by dissolving chloroiridium acid in anhydrous ethanol, with an iridium concentration of 10 g / L. The dip-pull and heat treatment steps are repeated twice.

[0069] S4. Monodisperse PS microspheres with a particle size of 850 nm were dispersed in anhydrous ethanol to prepare a suspension with a mass fraction of 2 wt.%. The substrate containing the IrO2 glaze layer obtained in step S3 was immersed and pulled in at a speed of 0.1 mm / s using the dip-coating method to form an ordered monolayer template. Subsequently, it was heated at 100℃ for 5 min to solidify and enhance the bonding force between the microspheres and the IrO2 glaze layer. The obtained substrate material was used as the working electrode for electrodeposition in the aged iridium electroplating solution. The scanning potential range of the electrodeposition was -0.6 V to 0.6 V (relative to the mercury-mercury oxide electrode), the scanning rate was 5 mV / s, the cycle was 30 times, and the deposition temperature was 25℃. The deposited material was immersed in toluene (analytical grade) for 48 h to remove the PS template. After rinsing with ethanol and drying, it was sintered in a muffle furnace at 400℃ for 2 h to obtain the electrochemically descaling porous iridium-based titanium anode. In the above steps, the pH of the iridium plating solution is 10.2. It is obtained by dissolving iridium salt, potassium oxalate, polyethylene glycol, and sodium dodecyl sulfate in deionized water. The concentration of iridium salt is 3.5 g / L, the concentration of potassium oxalate is 5 g / L, the molecular weight of polyethylene glycol is 1000, the concentration is 0.3 g / L, and the concentration of sodium dodecyl sulfate is 0.1 g / L.

[0070] It should be noted that the reagents and raw materials used in this invention can all be obtained through commercial purchases, and are not limited to this.

[0071] The SEM images of the porous iridium-based titanium anode prepared in this embodiment before and after removing the PS template are shown below. Figure 2 As shown, the results indicate that before removing the template (corresponding to...) Figure 2 (Left image) The material surface exhibits a highly ordered spherical structure, with tightly and regularly arranged particles and a relatively smooth surface; however, after removing the template (corresponding to...) Figure 2 (See right figure) The original spherical structure disappears, transforming into a network structure with abundant pores, forming numerous interconnected holes, and the surface becomes rough and uneven. This significant morphological change confirms the effectiveness of the template removal process, which can successfully transform the originally dense template structure into a porous anode material with a high specific surface area. This porous morphology greatly increases the active surface area of ​​the material, which is beneficial for the transport and diffusion of ions or gases during electrochemical reactions, and helps to improve the electrochemical performance of the anode material.

[0072] Examples 2 to 4

[0073] The only difference between Examples 2 to 4 and Example 1 is that the number of cycles in step S4 of the electrodeposition process is different from that in Example 1. The remaining experimental steps and parameters are the same as in Example 1, and will not be repeated here. The number of cycles and the iridium loading under the corresponding conditions for Examples 1 to 4 are shown in Table 1.

[0074] Table 1. Number of cycles and iridium loading under corresponding conditions for Examples 1 to 4

[0075]

[0076] Examples 5 to 7

[0077] The only difference between Examples 5 to 7 and Example 1 is that in step S4, the amount of polyethylene glycol and sodium dodecyl sulfate used in the iridium plating solution is different from that in Example 1. The other experimental steps and parameters are the same as those in Example 1, and will not be repeated here. The concentrations of polyethylene glycol and sodium dodecyl sulfate in Examples 1 and Examples 5 to 7 are shown in Table 2.

[0078] Table 2. Concentration settings of polyethylene glycol and sodium dodecyl sulfate in Examples 1 and 5 to 7

[0079]

[0080] Comparative Example 1

[0081] This comparative example provides a conventional anode preparation method, which includes the following steps: using a substrate of the same size as in Example 1, first etching it with oxalic acid, and using the resulting product as the working electrode, electrodepositing it in an iridium plating solution. The electrodeposition scanning potential range is -0.6 V to 0.6 V, the scanning rate is 5 mV / s, and the cycle is 30 times. The deposition charge is the same as in Example 1, thus obtaining an iridium-based titanium anode. The iridium plating solution has a pH of 10.2 and is obtained by dissolving iridium trichloride and potassium oxalate in deionized water, with an iridium salt concentration of 3.5 g / L and a potassium oxalate concentration of 5 g / L.

[0082] Comparative Example 2

[0083] The only difference between this comparative example and Example 1 is that the step of preparing the TiO2-SnO2 composite intermediate layer in step S1 is omitted, that is, the SnO2-IrO2 composite transition layer is directly prepared on the surface of the pretreated titanium substrate. The remaining experimental steps and parameters are the same as those in Example 1, and will not be repeated here.

[0084] Comparative Example 3

[0085] The only difference between this comparative example and Example 1 is that the step of preparing the IrO2 glaze layer in step S3 is omitted, that is, the PS single-layer template is directly prepared on the surface of the SnO2-IrO2 composite transition layer. The remaining experimental steps and experimental parameters are the same as those in Example 1, and will not be repeated here.

[0086] Comparative Example 4

[0087] The only difference between this comparative example and Example 1 is that the step of assembling a PS single-layer template on the IrO2 glaze layer in step S4 is omitted. That is, the titanium substrate containing the IrO2 glaze layer prepared in step S3 of Example 1 is directly electrodeposited. The specific experimental steps and experimental parameters are the same as those in Example 1, and will not be repeated here.

[0088] Comparative Example 5

[0089] The only difference between this comparative example and Example 1 is that polyethylene glycol and sodium dodecyl sulfate in the iridium plating solution in step S4 are omitted. The remaining experimental steps and parameters are the same as in Example 1, and will not be repeated here.

[0090] To evaluate the practical application potential of the porous iridium-based titanium anode prepared in Example 1, it was used as the anode and stainless steel as the cathode. Electrolysis of the water to be treated was performed under a DC electric field, operating under simulated conditions. The descaling rate and accelerated lifespan were tested. The descaling performance test conditions were as follows: current density 2 mA / cm². 2 The temperature was 25℃, the distance between the cathode and anode plates was 5cm, and the simulated circulating cooling water used in the test was prepared by adding anhydrous calcium chloride and sodium bicarbonate to deionized water. The water contained Ca... 2+ The concentration is 200 mg / L, HCO3 - The concentration was 400 mg / L. Accelerated life test conditions: 1 M H₂SO₄, 2 A / cm³. 2 .

[0091] The porous iridium-based titanium anode prepared in this invention is used for descaling, and its working principle is as follows: The porous anode prepared in this invention has a unique three-dimensional ordered porous structure and a highly catalytically active IrO2 surface, which can efficiently electrolytically release active oxygen species (such as ·OH, O3, etc.), forming a localized strong oxidation and strong acidic microenvironment on the electrode surface and inside the pores, thereby efficiently oxidizing, dissolving, and stripping calcium and magnesium deposits attached to the electrode surface. At the same time, the TiO2-SnO2 composite layer ensures efficient electron transport between the titanium substrate and the upper catalytic layer and effectively prevents passivation and corrosion of the titanium substrate; the SnO2-IrO2 composite transition layer further optimizes the electrochemical activity and thermal expansion matching of the electrode surface; and the dense and smooth IrO2 glaze layer not only enhances the affinity with the PS template, ensuring the integrity of the porous structure, but also improves the erosion resistance and corrosion resistance of the electrode surface. The synergistic effect between the layers ensures the stability and efficiency of the electrode in long-term operation.

[0092] The performance test results of the anodes prepared in Example 1 and Comparative Examples 1-4 are shown in Table 3. The results show that the descaling rate and enhanced lifespan of Example 1 are significantly better than those of all comparative examples. This is because the TiO2-SnO2 composite layer, SnO2-IrO2 composite transition layer, IrO2 glaze layer, and porous IrO2 deposition layer constructed in Example 1 form a stable multilayer synergistic structure. Among them, the TiO2-SnO2 composite layer can enhance the mechanical bonding force and electron transport capacity between the titanium substrate and the upper catalyst layer, effectively inhibiting the passivation and corrosion of the titanium substrate during long-term electrolysis; the SnO2-IrO2 composite transition layer can alleviate the thermal expansion mismatch problem between different layers, reduce the interfacial stress generated during heat treatment and long-term operation, thereby improving the overall stability of the electrode; the IrO2 glaze layer improves the interfacial affinity between the PS template and the substrate, ensuring the integrity and uniformity of the subsequently constructed porous structure, while enhancing the erosion resistance and corrosion resistance of the electrode surface.

[0093] Furthermore, Example 1 employed a PS microsphere template method to construct a highly ordered three-dimensional porous structure, significantly increasing the specific surface area and number of active sites of the electrode, while simultaneously shortening the ion diffusion path and improving Ca2+ efficiency. 2+ HCO 3- The high mass transfer efficiency of scale-forming ions and the localized strong oxidation and acidic microenvironment formed within the porous structure facilitate the oxidation, dissolution, and stripping of calcium and magnesium deposits, resulting in a higher descaling rate. Simultaneously, the introduction of polyethylene glycol and sodium dodecyl sulfate into the iridium plating solution effectively improves the uniformity and density of IrO2 deposition within the pores, reducing localized exposed and defective areas, thereby effectively delaying electrode deactivation and enhancing lifespan.

[0094] In contrast, Comparative Example 1 lacked a multi-layered composite structure and a porous structure, resulting in a lower electrode specific surface area and weaker interfacial bonding, thus significantly reducing descaling performance and stability. Comparative Example 2 lacked a TiO2-SnO2 composite layer, reducing electron transport capacity and interfacial bonding, leading to a significantly shortened enhancement lifespan. Comparative Example 3 lacked an IrO2 glaze layer, resulting in unstable bonding between the PS template and the substrate, poor integrity of the resulting pore structure, and affecting the uniformity of the deposited layer. Comparative Example 4 lacked a porous structure, limiting the effective reaction area of ​​the electrode and reducing ion diffusion efficiency, thus significantly decreasing the descaling rate. This demonstrates that the present invention, through the synergistic design of a multi-layered composite structure and an ordered porous structure, can significantly improve the descaling performance and long-term operational stability of the electrode.

[0095] Table 3. Performance comparison results of the anodes prepared in Example 1 and Comparative Examples 1-4

[0096]

[0097] The electrochemical descaling results of porous iridium-based titanium anodes prepared in Examples 1 and 1 to 4 are as follows: Figure 3 As shown, the results indicate that, under the same current density and flow field conditions, the porous iridium-based titanium anode prepared in Example 1 exhibits an excellent descaling rate (18.5 g·m⁻¹). -2 ·h -1 The intrinsic catalytic activity was enhanced (530 h). Comparative Example 1, lacking surface modification, exhibited lower intrinsic catalytic activity (7.2 g·m³). -2 ·h -1 The lifetime degradation (190 h) was due to matrix corrosion; although Comparative Example 2 improved the initial rate (12.9 g·m⁻¹) by increasing the iridium loading, it also resulted in a lower initial rate (190 h). -2 ·h -1 However, the bubble shielding effect and ohmic polarization caused by the dense coating lead to its rapid deactivation (85 h). The above results prove that only the iridium-based titanium anode prepared by the method proposed in this invention can break the trade-off between "activity and stability" in the traditional DSA anode and achieve long-term stable operation under high oxygen evolution overpotential.

[0098] The performance results of the iridium-based titanium anodes prepared under the conditions of Examples 1 to 7 and Comparative Example 5 are shown in Table 4. Compared with the other examples, the in-pore deposition of Example 1 exhibits a uniform and dense characteristic. This structure ensures both a large effective catalytic area and abundant active sites, while avoiding mass transfer limitation caused by pore blockage. Therefore, it achieves a high descaling rate (18.5 g·m³). -2 ·h -1 While achieving a long enhanced lifespan (520 h), this was primarily due to the optimal addition levels of PEG and SDS, which synergistically improved IrO. x Uniform deposition inside the pores forms a continuous and complete catalyst layer structure.

[0099] In Example 2, due to the thin deposition and insufficient number of active sites, the descaling rate and lifespan were both low. In Example 3, the deposition became more dense, increasing the number of active sites, resulting in the highest descaling rate. However, due to slight blockage at the pore edges, the long-term stability was somewhat affected. In Example 4, the pores were severely blocked. Although this improved the corrosion resistance and resulted in the highest lifespan (620 h), the ion mass transfer efficiency decreased, thus reducing the descaling rate.

[0100] In Examples 5 and 7, the deposition inside the pores is relatively uniform and the pore structure is complete, thus achieving both good stability and reactivity. However, due to the lower density of the deposition compared to Example 1, the number of active sites is relatively small, resulting in slightly lower overall performance. In Example 6, the deposition is dense and continuous, thus exhibiting a high descaling rate and lifespan. However, some pore openings shrink slightly, which affects the mass transfer efficiency to some extent.

[0101] In contrast, Comparative Example 5, due to its sparse deposits within the pores and the presence of exposed points, exhibited a reduced active area and was prone to localized failure, ultimately resulting in a lower descaling rate (14.2 g·m³). -2 ·h -1 The lowest values ​​for both the peak lifespan and the enhanced lifetime (380 h) indicate that a uniform and dense deposition layer can effectively prevent passivation, extend electrode lifespan, and maintain high catalytic activity.

[0102] Table 4 Performance results of iridium-based titanium anodes prepared under the conditions of Examples 1 to 7 and Comparative Example 5

[0103]

[0104] The above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention.

Claims

1. A method for preparing a porous iridium-based titanium anode for high-bonding electrochemical descaling, characterized in that, Includes the following steps: S1. The pretreated titanium substrate is immersed in an electroplating solution containing stannous sulfate, and a TiO2-SnO2 composite layer is obtained on the surface of the titanium substrate by constant current electrodeposition and thermal oxidation treatment. S2. Using a pyrolysis spraying method, a spraying liquid containing iridium salt and tin salt is sprayed onto the surface of the TiO2-SnO2 composite layer, and then subjected to thermal decomposition treatment to obtain a SnO2-IrO2 composite transition layer on the surface of the TiO2-SnO2 composite layer. S3. An iridium precursor solution is loaded onto the surface of the titanium substrate containing the SnO2-IrO2 composite transition layer obtained in step S2 to ensure that the iridium precursor solution is fully coated on the surface of the titanium substrate. Then, after heat treatment, a dense and smooth IrO2 glaze layer is obtained on the surface of the SnO2-IrO2 composite transition layer. S4. The titanium substrate containing the IrO2 glaze layer obtained in step S3 is immersed in the PS microsphere dispersion. An ordered monolayer template layer is assembled on the surface of the IrO2 glaze layer using the dip-coating method. Periodic electrodeposition is performed in the iridium electroplating solution. After removing the PS microsphere template layer, the porous iridium-based titanium anode is obtained through sintering.

2. The preparation method according to claim 1, characterized in that, In step S4, the pH of the iridium plating solution is 10-10.5, and it contains iridium salt, potassium oxalate, polyethylene glycol, and sodium dodecyl sulfate; the concentration of iridium salt in the iridium plating solution is 2.5-5.0 g / L, the concentration of potassium oxalate is 3-6 g / L, the concentration of polyethylene glycol is 0.1-0.5 g / L with a molecular weight of 400-2000, and the concentration of sodium dodecyl sulfate is 0.05-0.2 g / L.

3. The preparation method according to claim 1, characterized in that, In step S4, the scanning voltage range of the periodic electrodeposition is -0.6 V to 0.6 V, the scanning rate is 1-5 mV / s, and the number of cycles is 15-60.

4. The preparation method according to claim 1, characterized in that, In step S3, the iridium precursor solution is obtained by dissolving chloroiridium acid in anhydrous ethanol, and the iridium concentration is 5-15 g / L.

5. The preparation method according to claim 1, characterized in that, In step S2, the spraying solution includes chloroiridium acid, tin chloride, isopropanol and n-butanol, with an iridium concentration of 3-8 g / L, a tin concentration of 5-10 g / L, and a volume ratio of isopropanol to n-butanol of 1:3; the pyrolysis spraying temperature is 400-500℃, and the number of spraying times is 5-10.

6. The preparation method according to claim 1, characterized in that, In step S1, the process parameters for the constant current electrodeposition are as follows: current density of -5 to -10 mA / cm². 2 The deposition time is 15-30 min; the thermal oxidation treatment is performed at a temperature of 500℃ for 2 h.

7. The preparation method according to claim 1, characterized in that, In step S4, the particle size of the PS microspheres is 200 nm-4 μm; the sintering temperature is 350-450℃, and the holding time is 2 h.

8. An electrochemically descaling porous iridium-based titanium anode prepared by the method described in any one of claims 1-7, characterized in that, include: Titanium substrate; The composite functional layer includes a TiO2-SnO2 composite layer, a SnO2-IrO2 composite transition layer, and an IrO2 glaze layer stacked sequentially, wherein the TiO2-SnO2 composite layer is tightly bonded to the titanium substrate. The thickness of the TiO2-SnO2 composite layer is 1-5 μm, the thickness of the SnO2-IrO2 composite transition layer is 0.5-3 μm, and the thickness of the IrO2 glaze layer is 100-500 nm. The pore structure of the iridium-based titanium anode has a specific surface area of ​​15-60 m². 2 / g, with an average pore diameter of 200 nm-4 μm and a porosity of 35-75%.

9. The application of the porous iridium-based titanium anode for electrochemical descaling as described in claim 8 in electrochemical descaling, characterized in that, Includes the following steps: The anode and cathode are immersed in the circulating cooling water to be treated, and the water to be treated is electrolyzed under a DC electric field. The anode is the porous iridium-based titanium anode as described in claim 8. The electrolysis process occurs at a current density of 1-10 mA / cm². 2 The process is carried out at a temperature of 20-40℃, and the circulating cooling water contains Ca. 2+ and HCO3 - .

10. An electrochemical descaling device, characterized in that, Includes the electrochemical descaling porous iridium-based titanium anode as described in claim 8.

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