Anode for high-temperature continuous electrodeionization and method of making same

Abstract

The application discloses a high-temperature continuous electric desalination anode and a preparation method thereof. The high-temperature continuous electric desalination anode is composed of a titanium base body, an intermediate transition layer and a surface iridium-rich active layer, and comprises the following steps: dissolving polypyrrole derivative carbon-coated iridium oxide nanoparticles, tantalum salt and transition metal salt in a solvent, uniformly mixing, coating on the surface of the titanium base body, drying, heat oxidizing, then repeatedly coating multiple times, and heat treating to obtain a titanium anode containing the intermediate transition layer; dissolving polypyrrole derivative carbon-coated iridium oxide nanoparticles, tantalum salt and transition metal salt in a solvent, uniformly mixing, coating on the surface of the titanium anode containing the intermediate transition layer, drying, heat oxidizing, repeatedly coating multiple times, and finally heat treating. The application reduces the comprehensive cost of the iridium tantalum coating and prolongs the service time by amorphous carbon coating of iridium oxide nanoparticles, introduction of relatively cheap transition metal elements and gradient composition design, and the obtained anode exhibits excellent voltage stability characteristics at 75 DEG C.

Description

Technical Field

[0001] This invention belongs to the field of electrode material technology and relates to an anode for high-temperature continuous electro-desalination and its preparation method. Background Technology

[0002] Continuous electro-desalination is a novel water treatment technology that fills the spaces between ion exchange membranes with mixed-bed resin and achieves continuous desalination under the action of a DC electric field. It combines the advantages of continuous desalination by electrodialysis and deep desalination by ion exchange, and has broad application prospects in pure water preparation and wastewater treatment.

[0003] As a key component of continuous electrostatic precipitator (ESP), the selection of anode material significantly impacts the current efficiency, energy consumption, and service life of the ESP. During operation, the anode reaction typically releases chlorine gas (2Cl₂). - –2e→Cl2) and oxygen (H2O–2e→2H) + +1 / 2O2); As the oxygen evolution reaction proceeds at the anolyte, the acidity of the anolyte gradually increases. Therefore, the anode of the continuous electro-desalination system needs to be able to withstand complex chemical environments (strong oxidizing and strong acid).

[0004] Titanium-coated iridium-tantalum electrodes are currently the best-performing anodes in conventional continuous electrostatic desalination equipment. However, with the diversification and increasing complexity of water treatment applications, the service life of titanium-coated iridium-tantalum electrodes will significantly decrease under high-temperature and high-current environments (high-temperature conditions can increase the limiting current, which helps prevent polarization precipitation and reduce energy consumption, but will accelerate electrode failure). In addition, with the continuous rise in the price of metallic iridium, cost has also become an obstacle to the industrial use of titanium-coated iridium-tantalum electrodes.

[0005] In conclusion, finding an anode that reduces the amount of precious metal iridium and is suitable for higher temperature scenarios is of great practical significance for expanding the application scenarios of continuous electro-desalination technology. Summary of the Invention

[0006] In order to overcome the shortcomings of the prior art, the purpose of this invention is to provide a high-temperature continuous electro-desalination anode that can reduce the amount of precious metal iridium used and its preparation method.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A method for preparing an anode for high-temperature continuous electro-desalination includes a titanium substrate, an intermediate transition layer on the surface of the titanium substrate, and an iridium-rich active layer on the surface of the intermediate transition layer.

[0009] Furthermore, the intermediate transition layer comprises polypyrrole-derived carbon-coated iridium oxide nanoparticles, tantalum oxide, and transition metal oxide in a mass ratio of (100–140):(160–195):(20–40).

[0010] Furthermore, the surface iridium-rich active layer comprises polypyrrole-derived carbon-coated iridium oxide nanoparticles, tantalum oxide, and transition metal oxide in a mass ratio of (100–140):(60–90):(10–30).

[0011] A method for preparing an anode for high-temperature continuous electrostatic desalination includes the following steps:

[0012] (1) Polypyrrole-derived carbon-coated iridium oxide nanoparticles, tantalum salt and transition metal salt are dissolved in a solvent, mixed evenly and coated onto the surface of a titanium substrate, dried and thermally oxidized; then the coating, drying and thermal oxidation steps are repeated multiple times; finally heat treatment is performed to obtain a titanium anode containing an intermediate transition layer.

[0013] (2) Polypyrrole-derived carbon-coated iridium oxide nanoparticles, tantalum salt and transition metal salt are dissolved in a solvent, ultrasonically stirred and mixed at room temperature, and then coated on the surface of a titanium anode containing an intermediate transition layer, dried and thermally oxidized; the coating, drying and thermal oxidation steps are repeated multiple times; finally, heat treatment is performed to obtain an anode for high-temperature continuous electro-desalination.

[0014] Furthermore, the polypyrrole-derived carbon-coated iridium oxide nanoparticles in steps (1) and (2) are prepared by the following process:

[0015] Pyrrole was added to a solution containing ammonium persulfate and ammonium hexachloroiridate, stirred, and dried to obtain a polymerization product; the polymerization product was then pyrolyzed to obtain polypyrrole-derived carbon-coated iridium oxide nanoparticles.

[0016] Furthermore, the molar ratio of ammonium persulfate to pyrrole is 1:0.5 to 1.5, the molar ratio of ammonium hexachloroiridate to pyrrole is 1:10 to 50, the stirring time is 2 to 4 hours, the pyrolysis temperature is 300 to 700℃, and the pyrolysis time is 0.5 to 1 hour.

[0017] Furthermore, the tantalum salt in steps (1) and (2) is tantalum pentachloride;

[0018] The transition metal salt is at least one of cobalt nitrate hexahydrate, cobalt chloride hexahydrate, phosphomolybdic acid and ammonium molybdate tetrahydrate;

[0019] The solvent is at least one of ethanol, isopropanol, n-butanol, ethylene glycol, and N,N-dimethylformamide.

[0020] Furthermore, in step (1), the amounts of polypyrrole-derived carbon-coated iridium oxide nanoparticles, tantalum salts and transition metal salts are calculated according to the mass ratio of polypyrrole-derived carbon-coated iridium oxide nanoparticles: tantalum oxides: transition metal oxides = (100~140): (160~195): (20~40).

[0021] Furthermore, in step (2), the amounts of polypyrrole-derived carbon-coated iridium oxide nanoparticles, tantalum salts and transition metal salts are calculated according to the mass ratio of polypyrrole-derived carbon-coated iridium oxide nanoparticles: tantalum oxides: transition metal oxides = (100~140): (60~90): (10~30).

[0022] Furthermore, in step (1), the temperature of thermal oxidation is 400-500℃ and the time is 5-10 min; the temperature of heat treatment is 450-600℃ and the time is 0.5-2 h.

[0023] In step (2), the temperature of thermal oxidation is 300-600℃ and the time is 5-10 min; the temperature of heat treatment is 350-600℃ and the time is 0.5-2 h.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] (1) The present invention reduces the amount of precious metal iridium and reduces costs by designing a gradient composition between the intermediate transition layer and the surface iridium-rich active layer, and by introducing relatively inexpensive transition metal elements.

[0026] (2) In this invention, the tantalum oxide that has the function of protecting the active components has a higher content in the intermediate transition layer, which can better protect the titanium matrix; the iridium oxide that has good electrochemical activity has a higher content in the surface active layer, which can effectively exert its electrochemical performance.

[0027] (3) In this invention, transition metal elements (molybdenum, cobalt) are introduced into the intermediate transition layer and the surface iridium-rich active layer, which is beneficial to the densification of the iridium tantalum oxide coating, thereby inhibiting the penetration of active oxygen and electrolyte, slowing down the passivation of the titanium substrate, and improving the service life of the electrode.

[0028] (4) The amorphous carbon based on polypyrrole carbon in this invention has a certain conductivity. Its coating on iridium oxide nanoparticles can not only improve the effective charge conduction in the coating, promote the uniform distribution of iridium oxide nanoparticles in the active layer, and ensure a large electrochemical active area, but also reduce the thermal stress between different material interfaces, avoid the detachment of active points during high-temperature electrolysis, and inhibit the dissolution of active components, thereby helping to extend the service life of the electrode under complex working conditions (such as high temperature). Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, obtaining other drawings based on these drawings without creative effort still falls within the scope of the present invention.

[0030] Figure 1 This is a process flow diagram of a method for preparing an anode for high-temperature continuous electro-desalination according to the present invention;

[0031] Figure 2 This is a schematic diagram of the electrode structure of an anode for high-temperature continuous electro-desalination according to the present invention;

[0032] In the figure, 1 is the titanium substrate, 2 is the intermediate transition layer, and 3 is the iridium-rich active layer on the surface. Detailed Implementation

[0033] To enable those skilled in the art to better understand the present invention, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, not all embodiments, and are not intended to limit the scope of the present invention. Furthermore, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion regarding the concepts disclosed in the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort should fall within the scope of protection of the present invention.

[0034] See Figure 1 This invention discloses a method for preparing an anode for high-temperature continuous electrostatic desalination, comprising the following steps: Pre-treating a titanium substrate; preparing polypyrrole-derived carbon-coated iridium oxide nanoparticles via pyrolysis of a polypyrrole / iridium composite; preparing a precursor solution containing a carbon-coated iridium oxide, tantalum salt, and transition metal salt as an intermediate transition layer; coating the pre-treated titanium substrate surface 2-10 times and performing sintering heat treatment to form the intermediate transition layer; preparing a precursor solution containing a carbon-coated iridium oxide, tantalum salt, and transition metal salt as a surface-rich iridium active layer precursor solution; coating the surface containing the intermediate transition layer 3-6 times and performing sintering heat treatment to form the surface-rich iridium active layer.

[0035] (1) Pretreatment of the titanium matrix:

[0036] The titanium substrate is subjected to alkaline washing to remove oil, acid etching, water washing, and infrared drying to remove the surface titanium oxide film and obtain a clean titanium substrate.

[0037] (2) Preparation of polypyrrole-derived carbon-coated iridium oxide nanoparticles:

[0038] Ammonium persulfate and ammonium hexachloroiridate were dissolved separately in deionized water. After mixing, pyrrole was added under vigorous stirring to obtain a mixture. The molar ratio of ammonium persulfate to pyrrole was 1:0.5–1.5, and the molar ratio of ammonium hexachloroiridate to pyrrole was 1:10–50. The mixture was stirred in an ice-water mixing bath for 2–4 hours, and then freeze-dried to remove the solvent, yielding the polymer product. The freeze-dried polymer product was then pyrolyzed in a muffle furnace at 300–700°C for 0.5–1 hour. After naturally cooling to room temperature, soluble impurities were removed by washing with deionized water and high-speed centrifugation. The product was then vacuum-dried at 40–65°C to obtain polypyrrole-derived carbon-coated iridium oxide nanoparticles.

[0039] (3) Preparation of the intermediate transition layer:

[0040] The polypyrrole-derived carbon-coated iridium oxide nanoparticles obtained in step (2) were dissolved in a solvent along with tantalum salt and transition metal salt. The mixture was stirred ultrasonically at room temperature to form a precursor solution for the intermediate transition layer. The precursor solution of the intermediate transition layer was coated onto the surface of the titanium substrate pretreated in step (1), dried at 90–120°C for 10–15 min, and then oxidized in a muffle furnace at 400–500°C for 5–10 min. After natural cooling, the coating and thermal oxidation were repeated 2–10 times. Finally, the substrate was heat-treated at 450–600°C for 0.5–2 h and cooled to obtain a titanium anode containing the intermediate transition layer.

[0041] The tantalum salt mentioned is tantalum pentachloride.

[0042] The transition metal salt is at least one of cobalt nitrate hexahydrate, cobalt chloride hexahydrate, phosphomolybdic acid, and ammonium molybdate tetrahydrate.

[0043] The solvent is at least one selected from ethanol, isopropanol, n-butanol, ethylene glycol, and N,N-dimethylformamide.

[0044] The precursor solution of the intermediate transition layer can be added according to the different types and molecular weights of the metal salts, based on the mass ratio of polypyrrole-derived carbon-coated iridium oxide nanoparticles: tantalum oxide: transition metal oxide = (100-140): (160-195): (20-40).

[0045] The coating can be applied by brushing, dipping, or spraying. Considering the utilization rate of precious metals and the simplicity of operation, brushing is preferred.

[0046] (4) Preparation of the iridium-rich active layer on the surface:

[0047] Polypyrrole-derived carbon-coated iridium oxide nanoparticles, tantalum salt, and transition metal salt were dissolved in a solvent and ultrasonically stirred at room temperature to form a precursor solution with an iridium-rich active layer. The precursor solution with the iridium-rich active layer was coated onto the surface of the titanium anode containing the intermediate transition layer obtained in step (3). The titanium anode surface containing the intermediate transition layer was dried at 90–120°C for 10–15 min, thermally oxidized in a muffle furnace at 300–600°C for 5–10 min, and then coated and thermally oxidized again after natural cooling. The coating was repeated 3–6 times. Finally, the titanium anode containing the intermediate transition layer and the iridium-rich active layer was obtained after heat treatment annealing at 350–600°C for 0.5–2 h and cooling.

[0048] The tantalum salt mentioned is tantalum pentachloride.

[0049] The transition metal salt is at least one of cobalt nitrate hexahydrate, cobalt chloride hexahydrate, phosphomolybdic acid, and ammonium molybdate tetrahydrate.

[0050] The solvent is at least one selected from ethanol, isopropanol, n-butanol, ethylene glycol, and N,N-dimethylformamide.

[0051] The precursor solution of the surface-rich iridium active layer can be added according to the different types and molecular weights of the metal salts, based on the mass ratio of polypyrrole-derived carbon-coated iridium oxide nanoparticles: tantalum oxide: transition metal oxide = (100-140): (60-90): (10-30).

[0052] The coating can be applied by brushing, dipping, or spraying. Considering the utilization rate of precious metals and the simplicity of operation, brushing is preferred.

[0053] Preferably, the molar ratio of ammonium persulfate to pyrrole in step (2) above is 1:0.8-1.2, and the molar ratio of ammonium hexachloroiridate to pyrrole is 1:20-30. The pyrolysis temperature of the freeze-dried polymerization product in a muffle furnace is 400-500℃. When the pyrolysis temperature is too low, it is difficult to form nano-sized IrO with excellent catalytic activity. x Phase; when the pyrolysis temperature is too high, it will lead to IrO x The growth and aggregation of nanoparticles.

[0054] Preferably, the precursor solution of the intermediate transition layer in step (3) is coated 4 to 8 times. If the number of coatings of the precursor solution of the intermediate transition layer is too small, it is difficult to form an effective gradient coating; if the number of coatings of the precursor solution of the intermediate transition layer is too large, it will affect the conductivity and catalytic activity of the coating.

[0055] Preferably, the oxidation temperature in the muffle furnace in step (4) is 400-500°C. When the oxidation temperature is too low, the metal salt precursor will not be completely oxidized and decomposed; when the oxidation temperature is too high, it will lead to the oxidation of the titanium matrix.

[0056] Preferably, the heat treatment annealing temperature in step (4) is 400-500°C. When the heat treatment annealing temperature is too low, it is not conducive to completely eliminating the internal stress in the composite coating; when the heat treatment annealing temperature is too high, it will lead to the oxidation of the titanium substrate.

[0057] See Figure 2 The high-temperature continuous electro-desalination anode prepared by the method described above in this invention is composed of a titanium substrate 1, an intermediate transition layer 2 disposed on the titanium substrate, and an iridium-rich active layer 3 on the surface.

[0058] The intermediate transition layer comprises polypyrrole-derived carbon-coated iridium oxide nanoparticles, tantalum oxide, and transition metal oxide in a mass ratio of (100-140):(160-195):(20-40).

[0059] The surface iridium-rich active layer comprises polypyrrole-derived carbon-coated iridium oxide nanoparticles, tantalum oxide, and transition metal oxide in a mass ratio of (100-140):(60-90):(10-30).

[0060] The following are specific examples.

[0061] Example 1

[0062] A method for preparing an anode for high-temperature continuous electrostatic desalination includes the following steps:

[0063] (1) Pretreatment of titanium substrate: The titanium substrate was kept in a 7% NaOH solution at 80°C for 1 hour to remove oil. After rinsing with clean water, it was then placed in a slightly boiling 12% oxalic acid solution for 2-4 hours for etching. After cleaning with deionized water, it was dried by infrared to obtain a clean titanium substrate.

[0064] (2) Preparation of polypyrrole-derived carbon-coated iridium oxide nanoparticles:

[0065] 9.120 g of ammonium persulfate and 0.588 g of hexachloroiridate were dissolved in 28 mL and 80 mL of deionized water, respectively. After mixing, 2.681 g of pyrrole (molar ratio of ammonium persulfate to pyrrole: 1:1, molar ratio of ammonium hexachloroiridate to pyrrole: 1:30) was added under vigorous stirring. The resulting mixture was stirred in an ice-water mixing bath for 4 hours. Subsequently, the solvent was removed by freeze-drying to obtain a polypyrrole nanocomposite material with an embedded iridium complex. The obtained polypyrrole nanocomposite material with an embedded iridium complex was then placed in a crucible and placed in a muffle furnace, heated to 450 °C at a heating rate of 5 °C / min, and held for 1 hour. After naturally cooling to room temperature, soluble impurities were removed by washing with deionized water and high-speed centrifugation. The final product was vacuum dried at 65 °C to obtain polypyrrole-derived carbon-coated iridium oxide nanoparticles.

[0066] (3) Preparation of the intermediate transition layer:

[0067] The polypyrrole-derived carbon-coated iridium oxide nanoparticles (0.180 g) obtained in step (2) were dissolved in a 1:1 volume ratio of ethanol-n-butanol mixed solvent (10 mL) with tantalum pentachloride (0.478 g) and cobalt nitrate hexahydrate (0.181 g) to form a precursor solution for the intermediate transition layer. The precursor solution of the intermediate transition layer was uniformly coated onto the surface of the titanium substrate after the pretreatment in step (1) with a soft brush, dried at 110 °C for 10 min, and then thermally oxidized and decomposed at 450 °C for 8 min in a muffle furnace. After natural cooling, the coating was repeated, for a total of 6 coatings. Finally, the substrate was heat-treated at 450 °C for 1 h and cooled to obtain a titanium anode containing the intermediate transition layer.

[0068] In this embodiment, the mass ratio of polypyrrole-derived carbon-coated iridium oxide nanoparticles: tantalum oxide: transition metal cobalt oxide in the transition layer is 108:177:30.

[0069] (4) Preparation of the iridium-rich active layer on the surface:

[0070] The polypyrrole-derived carbon-coated iridium oxide nanoparticles (0.180 g) obtained in step (2) were dissolved in a 1:1 ethanol-n-butanol mixed solvent (6 mL) with tantalum pentachloride (0.205 g) and cobalt nitrate hexahydrate (0.115 g) at room temperature. The mixture was ultrasonically stirred at room temperature to form a precursor solution with an iridium-rich active layer. The precursor solution with an iridium-rich active layer was uniformly brushed onto the surface of the titanium anode containing the intermediate transition layer obtained in step (3) with a soft brush. The anode was dried at 110 °C for 10 min, then thermally oxidized at 450 °C for 8 min in a muffle furnace. After natural cooling, the anode was coated again, for a total of 4 coatings. Finally, the anode was heat-treated and annealed at 500 °C for 1 h. After cooling, a titanium anode containing an intermediate transition layer and an iridium-rich active layer was obtained, which is an anode for high-temperature continuous electro-desalination.

[0071] In this embodiment, the mass ratio of polypyrrole-derived carbon-coated iridium oxide nanoparticles, tantalum oxide, and transition metal cobalt oxide in the iridium-rich active layer is 108:76:19.

[0072] Example 2

[0073] A method for preparing an anode for high-temperature continuous electrostatic desalination includes the following steps:

[0074] (1) Pretreatment of titanium substrate: The titanium substrate was kept in a 7% NaOH solution at 80°C for 1 hour to remove oil. After rinsing with clean water, it was then placed in a slightly boiling 12% oxalic acid solution for 2 hours for etching. After cleaning with deionized water, it was dried by infrared to obtain a clean titanium substrate.

[0075] (2) Preparation of polypyrrole-derived carbon-coated iridium oxide nanoparticles:

[0076] 9.120 g of ammonium persulfate and 0.881 g of hexachloroiridium acid were dissolved in 28 mL and 80 mL of deionized water, respectively. After mixing, 1.341 g of pyrrole (molar ratio of ammonium persulfate to pyrrole: 1:0.5, molar ratio of ammonium hexachloroiridium acid to pyrrole: 1:10) was added under vigorous stirring. The resulting mixture was stirred in an ice-water mixing bath for 2 hours. Subsequently, the solvent was removed by freeze-drying to obtain a polypyrrole nanocomposite material with an embedded iridium complex. The obtained polypyrrole nanocomposite material with an embedded iridium complex was then placed in a crucible and placed in a muffle furnace, heated to 300 °C at a heating rate of 5 °C / min, and held for 1 hour. After naturally cooling to room temperature, soluble impurities were removed by washing with deionized water and high-speed centrifugation. The final product was vacuum dried at 40 °C to obtain polypyrrole-derived carbon-coated iridium oxide nanoparticles.

[0077] (3) Preparation of the intermediate transition layer:

[0078] The polypyrrole-derived carbon-coated iridium oxide nanoparticles (0.200 g), tantalum pentachloride (0.519 g), and cobalt chloride hexahydrate (0.145 g) obtained in step (2) were dissolved in ethanol (10 mL) and ultrasonically stirred at room temperature to form a precursor solution for the intermediate transition layer. The precursor solution for the intermediate transition layer was uniformly coated onto the surface of the titanium substrate after the pretreatment in step (1) with a soft brush, dried at 90 °C for 10 min, and then thermally oxidized at 400 °C for 10 min in a muffle furnace. After natural cooling, the substrate was coated again, for a total of 10 coatings. Finally, the substrate was heat-treated at 500 °C for 1 h and cooled to obtain a titanium anode containing the intermediate transition layer.

[0079] In this embodiment, the mass ratio of polypyrrole-derived carbon-coated iridium oxide nanoparticles: tantalum oxide: transition metal cobalt oxide in the transition layer is 100:160:20.

[0080] (4) Preparation of the iridium-rich active layer on the surface:

[0081] The polypyrrole-derived carbon-coated iridium oxide nanoparticles (0.200 g) obtained in step (2) were dissolved in ethanol (6 mL) along with tantalum pentachloride (0.195 g) and cobalt nitrate hexahydrate (0.073 g). The mixture was stirred ultrasonically at room temperature to form a precursor solution with an iridium-rich active layer. The precursor solution with the iridium-rich active layer was uniformly brushed onto the surface of the titanium anode containing the intermediate transition layer obtained in step (3) using a soft brush. The anode was dried at 90 °C for 10 min, then thermally oxidized at 300 °C for 10 min in a muffle furnace. After natural cooling, the anode was coated again, for a total of 6 coatings. Finally, the anode was heat-treated and annealed at 350 °C for 2 h. After cooling, a titanium anode containing the intermediate transition layer and the iridium-rich active layer was obtained, which is the anode for high-temperature continuous electro-desalination.

[0082] In this embodiment, the mass ratio of polypyrrole-derived carbon-coated iridium oxide nanoparticles: tantalum oxide: transition metal cobalt oxide in the surface iridium-rich active layer is approximately 100:60:10.

[0083] Example 3

[0084] A method for preparing an anode for high-temperature continuous electrostatic desalination includes the following steps:

[0085] (1) Pretreatment of titanium substrate: The titanium substrate was kept in a 7% NaOH solution at 80°C for 1 hour to remove oil. After rinsing with clean water, it was then placed in a slightly boiling 12% oxalic acid solution for 3 hours for etching. After cleaning with deionized water, it was dried by infrared to obtain a clean titanium substrate.

[0086] (2) Preparation of polypyrrole-derived carbon-coated iridium oxide nanoparticles:

[0087] 9.120 g of ammonium persulfate and 0.881 g of hexachloroiridate were dissolved in 28 mL and 80 mL of deionized water, respectively. After mixing, 4.022 g of pyrrole (molar ratio of ammonium persulfate to pyrrole: 1:1.5, molar ratio of ammonium hexachloroiridate to pyrrole: 1:30) was added under vigorous stirring. The resulting mixture was stirred in an ice-water mixing bath for 2 hours. Subsequently, the solvent was removed by freeze-drying to obtain a polypyrrole nanocomposite material with an iridium complex embedded. The obtained polypyrrole nanocomposite material with an iridium complex embedded was then placed in a crucible and placed in a muffle furnace, heated to 500 °C at a heating rate of 5 °C / min, and held for 1 hour. After naturally cooling to room temperature, soluble impurities were removed by washing with deionized water and high-speed centrifugation. The final product was vacuum dried at 65 °C to obtain polypyrrole-derived carbon-coated iridium oxide nanoparticles.

[0088] (3) Preparation of the intermediate transition layer:

[0089] By mass fraction, the polypyrrole-derived carbon-coated iridium oxide nanoparticles (0.280 g), tantalum pentachloride (0.584 g), and phosphomolybdic acid (0.063 g) obtained in step (2) were dissolved in a 1:1 volume ratio ethanol-isopropanol mixed solvent (10 mL). The mixture was ultrasonically stirred at room temperature to form a precursor solution for the intermediate transition layer. The precursor solution for the intermediate transition layer was uniformly brushed onto the surface of the titanium substrate after the pretreatment in step (1) with a soft brush. The substrate was dried at 100 °C for 12 min, then thermally oxidized at 500 °C for 5 min in a muffle furnace. After natural cooling, the substrate was coated again, for a total of 2 coatings. Finally, the substrate was heat-treated at 600 °C for 0.5 h and cooled to obtain a titanium anode containing the intermediate transition layer.

[0090] In this embodiment, the mass ratio of polypyrrole-derived carbon-coated iridium oxide nanoparticles, tantalum oxide, and transition metal cobalt oxide in the transition layer is 140:180:30.

[0091] (4) Preparation of the iridium-rich active layer on the surface:

[0092] The polypyrrole-derived carbon-coated iridium oxide nanoparticles (0.280 g), tantalum pentachloride (0.259 g), and phosphomolybdic acid (0.042 g) obtained in step (2) were dissolved in a 1:1 ethanol-isopropanol mixed solvent (6 mL). The mixture was ultrasonically stirred at room temperature to form a precursor solution with an iridium-rich active layer. The precursor solution with the iridium-rich active layer was uniformly brushed onto the surface of the titanium anode containing the intermediate transition layer obtained in step (3) using a soft brush. The anode was dried at 100 °C for 12 min, then thermally oxidized at 600 °C for 5 min in a muffle furnace. After natural cooling, the anode was coated again, for a total of 5 coatings. Finally, the anode was heat-treated and annealed at 600 °C for 0.5 h. After cooling, a titanium anode containing an intermediate transition layer and an iridium-rich active layer was obtained, which is an anode for high-temperature continuous electro-desalination.

[0093] In this embodiment, the mass ratio of polypyrrole-derived carbon-coated iridium oxide nanoparticles, tantalum oxide, and transition metal cobalt oxide in the surface iridium-rich active layer is 140:80:20.

[0094] Example 4

[0095] A method for preparing an anode for high-temperature continuous electrostatic desalination includes the following steps:

[0096] (1) Pretreatment of titanium substrate: The titanium substrate was kept in a 7% NaOH solution at 80°C for 1 hour to remove oil. After rinsing with clean water, it was then placed in a slightly boiling 12% oxalic acid solution for 4 hours for etching. After cleaning with deionized water, it was dried by infrared to obtain a clean titanium substrate.

[0097] (2) Preparation of polypyrrole-derived carbon-coated iridium oxide nanoparticles:

[0098] 9.120 g of ammonium persulfate and 0.529 g of hexachloroiridium acid were dissolved in 28 mL and 80 mL of deionized water, respectively. After mixing, 4.022 g of pyrrole (molar ratio of ammonium persulfate to pyrrole: 1:1.5, molar ratio of ammonium hexachloroiridium acid to pyrrole: 1:50) was added under vigorous stirring. The resulting mixture was stirred in an ice-water mixing bath for 2 hours. Subsequently, the solvent was removed by freeze-drying to obtain a polypyrrole nanocomposite material with an embedded iridium complex. The obtained polypyrrole nanocomposite material with an embedded iridium complex was then placed in a crucible and placed in a muffle furnace, heated to 700 °C at a heating rate of 5 °C / min, and held for 0.5 h. After naturally cooling to room temperature, soluble impurities were removed by washing with deionized water and high-speed centrifugation. The final product was vacuum dried at 50 °C to obtain polypyrrole-derived carbon-coated iridium oxide nanoparticles.

[0099] (3) Preparation of the intermediate transition layer:

[0100] By mass fraction, the polypyrrole-derived carbon-coated iridium oxide nanoparticles (0.240 g), tantalum pentachloride (0.632 g), and cobalt nitrate hexahydrate (0.290 g) obtained in step (2) were dissolved in a mixed solvent (10 mL) of ethanol and N,N-dimethylformamide at a volume ratio of 10:1. The mixture was ultrasonically stirred at room temperature to form a precursor solution for the intermediate transition layer. The precursor solution for the intermediate transition layer was uniformly brushed onto the surface of the titanium substrate after the pretreatment in step (1) with a soft brush. The substrate was dried at 120 °C for 15 min, then thermally oxidized at 420 °C for 8 min in a muffle furnace. After natural cooling, the substrate was coated again, for a total of 5 coatings. Finally, the substrate was heat-treated at 450 °C for 2 h and cooled to obtain a titanium anode containing the intermediate transition layer.

[0101] In this embodiment, the mass ratio of polypyrrole-derived carbon-coated iridium oxide nanoparticles, tantalum oxide, and transition metal cobalt oxide in the transition layer is 120:195:40.

[0102] (4) Preparation of the iridium-rich active layer on the surface:

[0103] The polypyrrole-derived carbon-coated iridium oxide nanoparticles (0.240 g) obtained in step (2) were dissolved in a mixed solvent (6 mL) of ethanol and ethylene glycol with a volume ratio of 10:1, along with tantalum pentachloride (0.292 g) and cobalt nitrate hexahydrate (0.217 g). The mixture was ultrasonically stirred at room temperature to form a precursor solution with an iridium-rich active layer. The precursor solution with the iridium-rich active layer was uniformly brushed onto the surface of the titanium anode containing the intermediate transition layer obtained in step (3) using a soft brush. The anode was dried at 120 °C for 15 min, then thermally oxidized at 500 °C for 7 min in a muffle furnace. After natural cooling, the anode was coated again, for a total of 3 coatings. Finally, the anode was heat-treated and annealed at 600 °C for 0.5 h. After cooling, a titanium anode containing an intermediate transition layer and an iridium-rich active layer was obtained, which is an anode for high-temperature continuous electro-desalination.

[0104] In this embodiment, the mass ratio of polypyrrole-derived carbon-coated iridium oxide nanoparticles, tantalum oxide, and transition metal cobalt oxide in the surface iridium-rich active layer is 120:90:30.

[0105] Example 5

[0106] A method for preparing an anode for high-temperature continuous electrostatic desalination includes the following steps:

[0107] (1) Pretreatment of titanium substrate: The titanium substrate was kept in a 7% NaOH solution at 80°C for 1 hour to remove oil. After rinsing with clean water, it was then placed in a slightly boiling 12% oxalic acid solution for 4 hours for etching. After cleaning with deionized water, it was dried by infrared to obtain a clean titanium substrate.

[0108] (2) Preparation of polypyrrole-derived carbon-coated iridium oxide nanoparticles:

[0109] 9.120 g of ammonium persulfate and 0.705 g of hexachloroiridium acid were dissolved in 28 mL and 80 mL of deionized water, respectively. After mixing, 2.145 g of pyrrole (molar ratio of ammonium persulfate to pyrrole: 1:0.8, molar ratio of ammonium hexachloroiridium acid to pyrrole: 1:20) was added under vigorous stirring. The resulting mixture was stirred in an ice-water mixing bath for 2 hours. Subsequently, the solvent was removed by freeze-drying to obtain a polypyrrole nanocomposite material with an iridium complex embedded. The obtained polypyrrole nanocomposite material with an iridium complex embedded was then placed in a crucible and placed in a muffle furnace, heated to 400 °C at a heating rate of 5 °C / min, and held for 0.5 h. After naturally cooling to room temperature, soluble impurities were removed by washing with deionized water and high-speed centrifugation. The final product was vacuum dried at 50 °C to obtain polypyrrole-derived carbon-coated iridium oxide nanoparticles.

[0110] (3) Preparation of the intermediate transition layer:

[0111] By mass fraction, the polypyrrole-derived carbon-coated iridium oxide nanoparticles (0.240 g), tantalum pentachloride (0.632 g), and cobalt nitrate hexahydrate (0.290 g) obtained in step (2) were dissolved in a mixed solvent (10 mL) of ethanol and N,N-dimethylformamide at a volume ratio of 10:1. The mixture was ultrasonically stirred at room temperature to form a precursor solution for the intermediate transition layer. The precursor solution for the intermediate transition layer was uniformly brushed onto the surface of the titanium substrate after the pretreatment in step (1) with a soft brush. The substrate was dried at 120 °C for 15 min, then thermally oxidized at 420 °C for 8 min in a muffle furnace. After natural cooling, the substrate was coated again, for a total of 4 coatings. Finally, the substrate was heat-treated at 450 °C for 2 h and cooled to obtain a titanium anode containing the intermediate transition layer.

[0112] In this embodiment, the mass ratio of polypyrrole-derived carbon-coated iridium oxide nanoparticles, tantalum oxide, and transition metal cobalt oxide in the transition layer is 120:195:40.

[0113] (4) Preparation of the iridium-rich active layer on the surface:

[0114] The polypyrrole-derived carbon-coated iridium oxide nanoparticles (0.240 g) obtained in step (2) were dissolved in a mixed solvent (6 mL) of ethanol and ethylene glycol with a volume ratio of 10:1, along with tantalum pentachloride (0.292 g) and cobalt nitrate hexahydrate (0.217 g). The mixture was ultrasonically stirred at room temperature to form a precursor solution with an iridium-rich active layer. The precursor solution with the iridium-rich active layer was uniformly brushed onto the surface of the titanium anode containing the intermediate transition layer obtained in step (3) using a soft brush. The anode was dried at 120 °C for 15 min, then thermally oxidized at 400 °C for 7 min in a muffle furnace. After natural cooling, the anode was coated again, for a total of 3 coatings. Finally, the anode was heat-treated and annealed at 400 °C for 0.5 h. After cooling, a titanium anode containing an intermediate transition layer and an iridium-rich active layer was obtained, which is an anode for high-temperature continuous electro-desalination.

[0115] In this embodiment, the mass ratio of polypyrrole-derived carbon-coated iridium oxide nanoparticles, tantalum oxide, and transition metal cobalt oxide in the surface iridium-rich active layer is 120:90:30.

[0116] Example 6

[0117] A method for preparing an anode for high-temperature continuous electrostatic desalination includes the following steps:

[0118] (1) Pretreatment of titanium substrate: The titanium substrate was kept in a 7% NaOH solution at 80°C for 1 hour to remove oil. After rinsing with clean water, it was then placed in a slightly boiling 12% oxalic acid solution for 4 hours for etching. After cleaning with deionized water, it was dried by infrared to obtain a clean titanium substrate.

[0119] (2) Preparation of polypyrrole-derived carbon-coated iridium oxide nanoparticles:

[0120] 9.120 g of ammonium persulfate and 0.846 g of hexachloroiridate were dissolved in 28 mL and 80 mL of deionized water, respectively. After mixing, 3.217 g of pyrrole (molar ratio of ammonium persulfate to pyrrole: 1:1.2, molar ratio of ammonium hexachloroiridate to pyrrole: 1:25) was added under vigorous stirring. The resulting mixture was stirred in an ice-water mixing bath for 2 hours. Subsequently, the solvent was removed by freeze-drying to obtain a polypyrrole nanocomposite material with an iridium complex embedded. The obtained polypyrrole nanocomposite material with an iridium complex embedded was then placed in a crucible and placed in a muffle furnace, heated to 700 °C at a heating rate of 5 °C / min, and held for 0.5 h. After naturally cooling to room temperature, soluble impurities were removed by washing with deionized water and high-speed centrifugation. The final product was vacuum dried at 50 °C to obtain polypyrrole-derived carbon-coated iridium oxide nanoparticles.

[0121] (3) Preparation of the intermediate transition layer:

[0122] By mass fraction, the polypyrrole-derived carbon-coated iridium oxide nanoparticles (0.240 g), tantalum pentachloride (0.632 g), and cobalt nitrate hexahydrate (0.290 g) obtained in step (2) were dissolved in a mixed solvent (10 mL) of ethanol and N,N-dimethylformamide at a volume ratio of 10:1. The mixture was ultrasonically stirred at room temperature to form a precursor solution for the intermediate transition layer. The precursor solution for the intermediate transition layer was uniformly brushed onto the surface of the titanium substrate after the pretreatment in step (1) with a soft brush. The substrate was dried at 120 °C for 15 min, then thermally oxidized at 420 °C for 8 min in a muffle furnace. After natural cooling, the substrate was coated again, for a total of 8 coatings. Finally, the substrate was heat-treated at 450 °C for 2 h and cooled to obtain a titanium anode containing the intermediate transition layer.

[0123] In this embodiment, the mass ratio of polypyrrole-derived carbon-coated iridium oxide nanoparticles, tantalum oxide, and transition metal cobalt oxide in the transition layer is 120:195:40.

[0124] (4) Preparation of the iridium-rich active layer on the surface:

[0125] The polypyrrole-derived carbon-coated iridium oxide nanoparticles (0.240 g) obtained in step (2) were dissolved in a mixed solvent (6 mL) of ethanol and ethylene glycol with a volume ratio of 10:1, along with tantalum pentachloride (0.292 g) and cobalt nitrate hexahydrate (0.217 g). The mixture was stirred ultrasonically at room temperature to form a precursor solution with an iridium-rich active layer. The precursor solution with the iridium-rich active layer was uniformly brushed onto the surface of the titanium anode containing the intermediate transition layer obtained in step (3) using a soft brush. The anode was dried at 120 °C for 15 min, then thermally oxidized at 550 °C for 7 min in a muffle furnace. After natural cooling, the anode was coated again, for a total of 3 coatings. Finally, the anode was heat-treated and annealed at 550 °C for 0.5 h. After cooling, a titanium anode containing an intermediate transition layer and an iridium-rich active layer was obtained, which is an anode for high-temperature continuous electro-desalination.

[0126] In this embodiment, the mass ratio of polypyrrole-derived carbon-coated iridium oxide nanoparticles, tantalum oxide, and transition metal cobalt oxide in the surface iridium-rich active layer is 120:90:30.

[0127] Comparative Example 1 (Undoped with transition metal)

[0128] A method for preparing an anode for high-temperature continuous electrostatic desalination includes the following steps:

[0129] (1) Pretreatment of titanium substrate: The titanium substrate was kept in a 7% NaOH solution at 80°C for 1 hour to remove oil; after rinsing with clean water, it was then placed in a slightly boiling 12% oxalic acid solution for 2-4 hours for etching; after cleaning with deionized water, it was dried by infrared to obtain a clean titanium substrate.

[0130] (2) Preparation of polypyrrole-derived carbon-coated iridium oxide nanoparticles:

[0131] 9.120 g of ammonium persulfate and 0.600 g of hexachloroiridate were dissolved in 28 mL and 80 mL of deionized water, respectively. After mixing, 2.760 g of pyrrole (molar ratio of ammonium persulfate to pyrrole: 1:1, molar ratio of ammonium hexachloroiridate to pyrrole: 1:30) was added under vigorous stirring. The mixture was stirred in an ice-water mixing bath for 4 hours. Subsequently, the solvent was removed by freeze-drying to obtain a polypyrrole nanocomposite material with an embedded iridium complex. The obtained polypyrrole nanocomposite material with an embedded iridium complex was then placed in a crucible and placed in a muffle furnace, heated to 450 °C at a heating rate of 5 °C / min, and held for 1 hour. After naturally cooling to room temperature, soluble impurities were removed by washing with deionized water and high-speed centrifugation. The final product was vacuum dried at 65 °C to obtain polypyrrole-derived carbon-coated iridium oxide nanoparticles.

[0132] (3) Preparation of the intermediate transition layer:

[0133] The polypyrrole-derived carbon-coated iridium oxide nanoparticles (0.180 g) obtained in step (2) and tantalum pentachloride (0.478 g) were dissolved in a 1:1 volume ratio ethanol-n-butanol mixed solvent (10 mL), and the mixture was ultrasonically stirred at room temperature to form a precursor solution for the intermediate transition layer. The precursor solution for the intermediate transition layer was uniformly brushed onto the surface of the titanium substrate after the pretreatment in step (1) with a soft brush, dried at 110 °C for 10 min, and then thermally oxidized at 450 °C for 8 min in a muffle furnace. After natural cooling, the substrate was coated again, for a total of 6 coatings. Finally, the substrate was heat-treated at 450 °C for 1 h, and after cooling, a titanium anode containing the intermediate transition layer was obtained.

[0134] In this comparative transition layer, the mass ratio of polypyrrole-derived carbon-coated iridium oxide nanoparticles: tantalum oxide: transition metal cobalt oxide is 108:177:0.

[0135] (4) Preparation of the iridium-rich active layer on the surface:

[0136] The polypyrrole-derived carbon-coated iridium oxide nanoparticles (0.180 g) obtained in step (2) and tantalum pentachloride (0.205 g) were dissolved in a 1:1 volume ratio ethanol-n-butanol mixed solvent (6 mL). The mixture was ultrasonically stirred at room temperature to form a precursor solution with an iridium-rich active layer. The precursor solution with the iridium-rich active layer was uniformly brushed onto the surface of the titanium anode containing the intermediate transition layer obtained in step (3) using a soft brush. The anode was dried at 110 °C for 10 min, then thermally oxidized at 450 °C for 8 min in a muffle furnace. After natural cooling, the anode was coated again, for a total of 4 coatings. Finally, the anode was heat-treated and annealed at 500 °C for 1 h. After cooling, a titanium anode containing an intermediate transition layer and an iridium-rich active layer was obtained.

[0137] In this comparative example, the mass ratio of polypyrrole-derived carbon-coated iridium oxide nanoparticles: tantalum oxide: transition metal cobalt oxide in the iridium-rich active layer is 108:76:0.

[0138] Comparative Example 2 (using hexachloroiridium acid instead of polypyrrole-derived carbon to coat iridium oxide nanoparticles)

[0139] A method for preparing an anode for high-temperature continuous electrostatic desalination includes the following steps:

[0140] (1) Pretreatment of titanium substrate: The titanium substrate was kept in a 7% NaOH solution at 80°C for 1 hour to remove oil; after rinsing with clean water, it was then placed in a slightly boiling 12% oxalic acid solution for 2-4 hours for etching; after cleaning with deionized water, it was dried by infrared to obtain a clean titanium substrate.

[0141] (2) Preparation of the intermediate transition layer:

[0142] Chloroiridic acid (0.327 g), tantalum pentachloride (0.48 g), and cobalt nitrate hexahydrate (0.18 g) were dissolved in a 1:1 ethanol-n-butanol mixed solvent (10 mL). The mixture was ultrasonically stirred at room temperature to form a precursor solution for the intermediate transition layer. The precursor solution for the intermediate transition layer was uniformly brushed onto the surface of the titanium substrate after the pretreatment in step (1) with a soft brush. The substrate was dried at 110 °C for 10 min, then thermally oxidized at 450 °C for 8 min in a muffle furnace. After natural cooling, the substrate was coated again, for a total of 6 coatings. Finally, the substrate was heat-treated at 450 °C for 1 h and cooled to obtain a titanium anode containing the intermediate transition layer.

[0143] In this comparative transition layer, the mass ratio of iridium oxide: tantalum oxide: transition metal cobalt oxide is 108:177:30.

[0144] (3) Preparation of the iridium-rich active layer on the surface:

[0145] 0.327 g of chloroiridic acid, 0.205 g of tantalum pentachloride, and 0.115 g of cobalt nitrate hexahydrate were dissolved in a 1:1 ethanol-n-butanol mixed solvent (6 mL). The mixture was ultrasonically stirred at room temperature to form a precursor solution with an iridium-rich active layer. The precursor solution with the iridium-rich active layer was uniformly brushed onto the surface of the titanium anode containing the intermediate transition layer obtained in step (3) using a soft brush. The anode was dried at 110 °C for 10 min, then thermally oxidized at 450 °C for 8 min in a muffle furnace. After natural cooling, the anode was coated again, for a total of 4 coatings. Finally, the anode was heat-treated and annealed at 500 °C for 1 h. After cooling, a titanium anode containing an intermediate transition layer and an iridium-rich active layer was obtained.

[0146] In this comparative example, the mass ratio of iridium oxide: tantalum oxide: transition metal cobalt oxide in the iridium-rich active layer is 108:76:19.

[0147] Comparative Example 3 (undoped transition metals, iridium oxide nanoparticles coated with hexachloroiridium acid instead of polypyrrole-derived carbon)

[0148] A method for preparing an anode for high-temperature continuous electrostatic desalination includes the following steps:

[0149] (1) Pretreatment of titanium substrate: The titanium substrate was kept in a 7% NaOH solution at 80°C for 1 hour to remove oil; after rinsing with clean water, it was then placed in a slightly boiling 12% oxalic acid solution for 2-4 hours for etching; after cleaning with deionized water, it was dried by infrared to obtain a clean titanium substrate.

[0150] (2) Preparation of the intermediate transition layer:

[0151] 0.327 g of chloroiridic acid and 0.478 g of tantalum pentachloride were dissolved in 10 mL of a 1:1 mixture of ethanol and n-butanol. The mixture was ultrasonically stirred at room temperature to form a precursor solution for the intermediate transition layer. The precursor solution for the intermediate transition layer was uniformly brushed onto the surface of the titanium substrate after the pretreatment in step (1) with a soft brush. The substrate was dried at 110 °C for 10 min, then thermally oxidized at 450 °C for 8 min in a muffle furnace. After natural cooling, the substrate was coated again, for a total of 6 coatings. Finally, the substrate was heat-treated at 450 °C for 1 h and cooled to obtain a titanium anode containing the intermediate transition layer.

[0152] In this comparative transition layer, the mass ratio of iridium oxide: tantalum oxide: transition metal cobalt oxide is 108:177:0.

[0153] (3) Preparation of the iridium-rich active layer on the surface:

[0154] 0.327 g of chloroiridic acid and 0.205 g of tantalum pentachloride were dissolved in a 1:1 mixture of ethanol and n-butanol (6 mL) and ultrasonically stirred at room temperature to form a precursor solution for the intermediate transition layer. The precursor solution for the intermediate transition layer was uniformly brushed onto the surface of the titanium anode containing the intermediate transition layer obtained in step (3) using a soft brush. The anode was dried at 110 °C for 10 min, then thermally oxidized at 450 °C for 8 min in a muffle furnace. After natural cooling, the anode was coated again, for a total of 4 coatings. Finally, the anode was annealed at 500 °C for 1 h and cooled to obtain a titanium anode containing the intermediate transition layer and an iridium-rich active layer on the surface.

[0155] In this comparative example, the mass ratio of iridium oxide: tantalum oxide: transition metal cobalt oxide in the iridium-rich active layer is 108:76:0.

[0156] Enhanced electrolysis life measurement: The anode in the embodiment was processed to have an electrode area of ​​5 cm². 2 The sample used a pure titanium sheet as the cathode, with a current density of 1 A / cm². 2 The enhanced electrolysis lifetime of the electrode was determined by controlling the temperature at 75℃ in a 1.0 mol / L H2SO4 electrolytic solution and measuring the time required for the electrolysis voltage to increase by 10V relative to the initial electrolysis value. The obtained enhanced electrolysis lifetimes are shown in Table 1.

[0157] Table 1

[0158] Group Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Enhanced electrolysis life (h) 2503 2176 2214 1926

[0159] Compared to Comparative Example 3, Comparative Example 1, which uses polypyrrole-derived carbon-coated iridium oxide nanoparticles as the iridium source, showed a 12.98% improvement in enhanced electrolysis lifetime, while Comparative Example 2, which introduced a transition metal, showed a 14.95% improvement. Furthermore, Example 1, which used both carbon-coated iridium oxide nanoparticles as the iridium source and introduced a transition metal, showed a 29.96% improvement in enhanced electrolysis lifetime. This demonstrates that both carbon-coated iridium oxide nanoparticles as the iridium source and transition metal doping can effectively improve the high-temperature service life of titanium-coated iridium-tantalum anodes. The most significant improvement in enhanced electrolysis lifetime was achieved through the synergistic effect between carbon-coated iridium oxide nanoparticles as the iridium source and transition metal doping.

[0160] This invention employs amorphous carbon coating of iridium oxide nanoparticles and introduces relatively inexpensive transition metal elements in combination with a gradient composition design, effectively reducing the overall cost of iridium-tantalum coatings and significantly improving the service life of titanium-coated iridium-tantalum anodes at 75°C. The anode exhibits excellent voltage stability characteristics at 75°C, solving the problems of high cost and significantly shortened service life in high-temperature scenarios of traditional titanium-coated iridium-tantalum anodes.

[0161] In this invention, tantalum oxide, which has the function of protecting active components, has a higher content in the intermediate transition layer, and iridium oxide, which has good electrochemical activity, has a higher content in the surface active layer. There is a gradient composition design between the intermediate transition layer and the surface iridium-rich active layer.

[0162] In this invention, the intermediate transition layer and the surface iridium-rich active layer were prepared using amorphous carbon-coated iridium oxide nanoparticles based on polypyrrole carbonization; simultaneously, relatively inexpensive transition metal elements were added. These transition metal elements include, but are not limited to, cobalt and molybdenum.

[0163] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the specific implementation of the present invention. Any modifications or equivalent substitutions that do not depart from the spirit and scope of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing an anode for high-temperature continuous electro-desalination, characterized in that, Includes the following steps: (1) Polypyrrole-derived carbon-coated iridium oxide nanoparticles, tantalum salt and transition metal salt are dissolved in a solvent, mixed evenly and coated on the surface of a titanium substrate, dried and thermally oxidized; then the coating, drying and thermal oxidation steps are repeated multiple times; finally heat treatment is performed to obtain a titanium anode containing an intermediate transition layer. (2) Polypyrrole-derived carbon-coated iridium oxide nanoparticles, tantalum salt and transition metal salt are dissolved in a solvent, ultrasonically stirred at room temperature and mixed evenly, and then coated on the surface of a titanium anode containing an intermediate transition layer, dried and thermally oxidized; and the coating, drying and thermal oxidation steps are repeated multiple times; finally, heat treatment is performed to obtain an anode for high-temperature continuous electro-desalination. The polypyrrole-derived carbon-coated iridium oxide nanoparticles in steps (1) and (2) are prepared by the following process: Pyrrole was added to a solution containing ammonium persulfate and ammonium hexachloroiridate, stirred, and dried to obtain the polymer product; The polymerization product was pyrolyzed to obtain polypyrrole-derived carbon-coated iridium oxide nanoparticles; The tantalum salt in steps (1) and (2) is tantalum pentachloride; The transition metal salt is at least one of cobalt nitrate hexahydrate, cobalt chloride hexahydrate, phosphomolybdic acid and ammonium molybdate tetrahydrate; The solvents are ethanol, isopropanol, n-butanol, ethylene glycol, and... N , N At least one of dimethylformamide; The anode for high-temperature continuous electro-desalination includes a titanium substrate, an intermediate transition layer on the surface of the titanium substrate, and an iridium-rich active layer on the surface of the intermediate transition layer. The intermediate transition layer comprises polypyrrole-derived carbon-coated iridium oxide nanoparticles, tantalum oxide, and transition metal oxide in a mass ratio of (100~140):(160~195):(20~40); The surface is rich in iridium active layer, which includes polypyrrole-derived carbon-coated iridium oxide nanoparticles, tantalum oxide and transition metal oxide in a mass ratio of (100~140):(60~90):(10~30).

2. The method for preparing the anode for high-temperature continuous electro-desalination according to claim 1, characterized in that, The molar ratio of ammonium persulfate to pyrrole is 1:0.5~1.5, the molar ratio of ammonium hexachloroiridate to pyrrole is 1:10~50, the stirring time is 2~4 hours, the pyrolysis temperature is 300~700℃, and the pyrolysis time is 0.5~1 hours.

3. The method for preparing the anode for high-temperature continuous electro-desalination according to claim 1, characterized in that, In step (1), the amounts of polypyrrole-derived carbon-coated iridium oxide nanoparticles, tantalum salts and transition metal salts are calculated according to the mass ratio of polypyrrole-derived carbon-coated iridium oxide nanoparticles: tantalum oxides: transition metal oxides = (100~140): (160~195): (20~40).

4. The method for preparing the anode for high-temperature continuous electro-desalination according to claim 1, characterized in that, In step (2), the amounts of polypyrrole-derived carbon-coated iridium oxide nanoparticles, tantalum salts and transition metal salts are calculated according to the mass ratio of polypyrrole-derived carbon-coated iridium oxide nanoparticles: tantalum oxides: transition metal oxides = (100~140): (60~90): (10~30).

5. The method for preparing the anode for high-temperature continuous electro-desalination according to claim 1, characterized in that, In step (1), the temperature of thermal oxidation is 400-500 ℃ and the time is 5-10 min; the temperature of heat treatment is 450~600℃ and the time is 0.5~2h. In step (2), the temperature of thermal oxidation is 300~600 ℃ and the time is 5-10 min; the temperature of heat treatment is 350~600 ℃ and the time is 0.5~2 h.

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