High-catalytic-activity palladium-doped Ir-Sn oxide titanium anode and preparation method thereof

Abstract

The invention discloses a palladium-doped Ir-Sn oxide titanium anode with high catalytic activity and a preparation method of the palladium-doped Ir-Sn oxide titanium anode, and belongs to the technical field of electrolytic anodes. The anode comprises a titanium substrate, a TiO2-Ta2O5 intermediate layer and an Ir-Sn-Pd oxide catalyst layer, the molar ratio of Ir to Sn to Pd in the catalyst layer is (5-6): 3: (1-2), and the total metal ion concentration is 0.3 mol L. The preparation method is realized through titanium substrate pretreatment (sand blasting and etching), intermediate layer coating sintering (a TiCl4-TaCl5 solution) and catalyst layer circulating coating sintering (an H2IrCl6-SnCl4-PdCl2 mixed solution). The relatively cheap palladium element is introduced, the electron structure of the catalyst layer is optimized by utilizing the defect effect, the charge transfer resistance is reduced to 6.7 omegacm, and meanwhile, the iridium consumption is reduced by more than 30%. Experiments show that the cell voltage of the anode is stabilized at 0.95 V (the current density is 5Acm <-2 >), the accelerated life reaches 1630 hours, the coating binding force is 62N, and the corrosion rate in an acidic electrolyte is only 0.01 mm / year. Compared with a traditional iridium tantalum anode, the cost is reduced by 40%, and the overpotential in the oxygen evolution reaction is as low as 0.45 V.

Description

Technical Field

[0001] The invention relates to the technical field of electrolytic anode preparation, in particular to a palladium-doped Ir-Sn oxide titanium anode with high catalytic activity and a preparation method thereof. Background Art

[0002] With the advancement of materials science and electrochemical technology, the performance of titanium-based metal oxide electrodes has been continuously improved. The use of titanium-based metal oxide electrodes not only improves the efficiency of industrial production, but also reduces the generation of waste electrodes due to its corrosion resistance and long working life. It has positive significance for environmental protection and is widely used in copper foil surface treatment, cathodic protection, sewage treatment and other fields.

[0003] Titanium-based metal oxide electrodes use valve metal titanium as a substrate, with a layer of catalytically active oxide prepared on its surface as an active coating. Titanium-based ruthenium-based anodes and titanium-based iridium-based anodes have demonstrated excellent performance in industrial production due to their high current density carrying capacity, low electrode potential and excellent chemical stability, and have become the preferred electrode materials in many fields. However, with the continuous growth of market demand for electrolytic copper foil, the requirements for anode materials are indeed getting higher and higher. Although traditional iridium-tantalum anodes have certain advantages in performance, their high cost and limited resources limit their large-scale application. Therefore, it is particularly important to develop new low-cost and highly catalytically active anode materials. Through material design and process optimization, low-cost, high-activity and high-stability anode preparation can be achieved, which can break through the limitations of traditional anodes in large-scale applications in electrolytic copper foil, sewage treatment and other fields.

[0004] Therefore, it is necessary to provide a palladium-doped Ir-Sn oxide titanium anode with high catalytic activity and a preparation method thereof to solve the above technical problems. Summary of the Invention

[0005] The purpose of the present invention is to provide a high catalytic activity palladium doped Ir-Sn oxide titanium anode and its preparation method, to solve the high cost problem of traditional titanium-based iridium anode due to the scarcity of iridium resources, as well as the existing low-cost anode materials with insufficient catalytic activity (high charge transfer resistance, large oxygen evolution overpotential), weak coating adhesion (easy to fall off), poor corrosion resistance (especially in Cl-containing - medium) and other technical issues.

[0006] To achieve the above object, the present invention provides the following technical solutions: In a first aspect, the present invention provides a high catalytic activity palladium-doped Ir-Sn oxide titanium anode, comprising the following components arranged in sequence: Base: Made of titanium or titanium alloy; Middle layer: contains TiO2 and Ta2O5; Catalytic layer: containing oxides of Ir, Sn, and Pd; The molar ratio of Ir, Sn, and Pd in ​​the catalyst layer is (5-6):3:(1-2), and the total metal ion concentration is 0.3 mol·L -1 .

[0007] In a second aspect, the present invention provides a method for preparing a palladium-doped Ir-Sn oxide titanium anode with high catalytic activity, comprising the following steps: (1) Pretreatment of the titanium substrate: cutting, sandblasting, etching, cleaning and drying the titanium substrate to obtain a pretreated titanium substrate; (2) Preparation of the intermediate layer: coating the intermediate layer base liquid on the surface of the titanium substrate pretreated in step (1), drying it in a high-temperature furnace, and repeating the coating → drying → cooling steps several times after cooling; (3) Preparation of catalytic layer liquid: Dissolve the iridium source, tin source, and palladium source in an organic solvent and stir until completely dissolved to form a total metal ion concentration of 0.3 mol·L -1 A mixed solution, wherein the molar ratio of Ir:Sn:Pd is (5-6):3:(1-2); (4) Preparation of catalytic layer: The mixed solution obtained in step (3) is evenly coated on the surface of the titanium substrate obtained in step (2), taken out after drying and sintering, and naturally cooled to room temperature, and then the above-mentioned coating → drying → sintering process is repeated to obtain a titanium anode with a palladium-doped Ir-Sn oxide coating.

[0008] Preferably, in step (1), the titanium substrate is cut and sandblasted, then alkaline washed with 10% NaOH solution for degreasing for 0.5 h, and then etched in a boiling etching solution. After etching, it is washed with pure water and dried to obtain the pretreated titanium substrate.

[0009] Preferably, in step (1), the etching treatment uses hydrochloric acid with a concentration of 5% to 25%, oxalic acid with a concentration of 4% to 10%, or sulfuric acid with a concentration of 10% to 30%, and the etching time is 5 to 30 minutes.

[0010] Preferably, in step (1), in the pretreatment of the titanium substrate, the sandblasting is performed using quartz sand with a particle size of 100 to 300 meshes and a sandblasting pressure of 0.4 to 0.6 MPa.

[0011] Preferably, in step (2), the intermediate layer base liquid is a mixed solution of TiCl4 and TaCl5. After the intermediate layer base liquid is applied, it is dried in an oven at a temperature of 65 to 75°C for 10 to 20 minutes, and then placed in a sintering furnace at a temperature of 450 to 600°C for 5 to 30 minutes. After cooling, the coating → drying → cooling steps are repeated 2 to 6 times; in step (2), the intermediate layer base liquid is applied by dipping, spraying or brushing.

[0012] Preferably, in step (3), the organic solvent is a mixture of one or more of n-butanol, ethanol, ethylene glycol, isopropanol or propanol.

[0013] Preferably, in step (3), in the catalytic layer, the iridium source is H2IrCl6, the tin source is SnCl4, and the palladium source is PdCl2.

[0014] Preferably, in step (3), the iridium source is first dissolved in an organic solvent, stirred until completely dissolved, and then the tin source and palladium source are added.

[0015] Preferably, in step (4), the drying temperature is 60-100°C, and the drying time is 10-20 minutes; the sintering temperature is 450-600°C, and the sintering time is 10-40 minutes each time. After sintering, the temperature is kept warm for 10-30 minutes within the same temperature range; after the temperature is kept warm, the titanium anode is taken out and naturally cooled to room temperature, and the process is repeated 16-20 times.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. The iridium-tin oxide-coated titanium anode prepared by the present invention achieves excellent electrochemical performance and corrosion resistance through the synergistic effect of tin oxide and iridium oxide.

[0017] 2. The present invention adopts an iridium-tin coating system. The iridium-tin coating system has excellent chemical stability due to the similarity of the crystal structure of its components. This characteristic significantly improves the durability of related titanium anode products and extends their service life.

[0018] 3. The present invention introduces the relatively cheap precious metal element palladium doping, utilizes the synergistic effect and defect effect, and effectively reduces the amount of precious metal used while significantly reducing the charge transfer resistance and further improving the electrocatalytic activity. It has application advantages in electrolytic copper foil, cathodic protection, and sewage treatment. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic structural diagram of the palladium-doped Ir-Sn oxide titanium anode of the present invention; Figure 2 This is a SEM surface morphology image of the titanium anode in Example 1 of the present invention; Figure 3 This is an AC impedance diagram that can reflect the electrocatalytic activity of Examples 1 to 3 and Comparative Example 1 in the present invention. DETAILED DESCRIPTION

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making any creative efforts shall fall within the scope of protection of the present invention.

[0021] The present invention aims to improve the catalytic activity, stability and corrosion resistance of the anode by optimizing the material composition and structure. Provided is a high catalytic activity palladium-doped Ir-Sn oxide titanium anode and a preparation method thereof. The titanium substrate is pre-treated to form a rough structure with an overall uniform distribution on its surface, and then a mixed metal salt solution of iridium, tin and palladium is coated on the surface of the titanium substrate. A dense structure intermediate layer is prepared by thermal decomposition, and finally a low proportion of precious metal salt solution is cyclically coated on the surface of the intermediate layer, and a precious metal oxide catalytic layer is formed by high-temperature sintering. Figure 1 As shown, the titanium anode includes a substrate 1, an intermediate layer 2, and a catalytic layer 3, specifically comprising the following components: Base: Made of titanium or titanium alloy; Middle layer: contains TiO2 and Ta2O5; Catalytic layer: containing oxides of Ir, Sn, and Pd; The molar ratio of Ir, Sn, and Pd in ​​the catalyst layer is (5-6):3:(1-2), and the total metal ion concentration is 0.3 mol·L -1 .

[0022] The method for preparing the palladium-doped Ir-Sn oxide titanium anode with high catalytic activity comprises the following steps: (1) Pretreatment of the titanium substrate: cutting, sandblasting, etching, cleaning and drying the titanium substrate to obtain a pretreated titanium substrate; (2) Preparation of the intermediate layer: coating the intermediate layer base liquid on the surface of the titanium substrate pretreated in step (1), drying it in a high-temperature furnace, and repeating the coating → drying → cooling steps several times after cooling; (3) Preparation of catalytic layer liquid: Dissolve the iridium source, tin source, and palladium source in an organic solvent and stir until completely dissolved to form a total metal ion concentration of 0.3 mol·L -1 A mixed solution, wherein the molar ratio of Ir:Sn:Pd is (5-6):3:(1-2); (4) Preparation of catalytic layer: The mixed solution obtained in step (3) is evenly coated on the surface of the titanium substrate obtained in step (2), taken out after drying and sintering, and naturally cooled to room temperature, and then the above-mentioned coating → drying → sintering process is repeated to obtain a titanium anode with a palladium-doped Ir-Sn oxide coating.

[0023] More specifically, in step (1), the titanium substrate is cut and sandblasted, then alkaline washed with a 10% NaOH solution for degreasing for 0.5 h, and then etched in a boiling etching solution. After etching, it is washed with pure water and dried to obtain the pretreated titanium substrate.

[0024] More specifically, in step (1), the etching treatment uses hydrochloric acid with a concentration of 5% to 25%, oxalic acid with a concentration of 4% to 10%, or sulfuric acid with a concentration of 10% to 30%, and the etching time is 5 to 30 minutes.

[0025] More specifically, in step (1), in the titanium substrate pretreatment, the sandblasting treatment uses quartz sand with a particle size of 100 to 300 meshes and a sandblasting pressure of 0.4 to 0.6 MPa.

[0026] More specifically, in step (2), the intermediate layer base liquid is a mixed solution of TiCl4 and TaCl5. After the intermediate layer base liquid is applied, it is dried in an oven at a temperature of 65 to 75°C for 10 to 20 minutes, and then placed in a sintering furnace at a temperature of 450 to 600°C for 5 to 30 minutes. After cooling, the coating → drying → cooling steps are repeated 2 to 6 times; in step (2), the intermediate layer base liquid is applied by dipping, spraying or brushing.

[0027] More specifically, in step (3), the organic solvent is a mixture of one or more of n-butanol, ethanol, ethylene glycol, isopropanol or propanol.

[0028] More specifically, in step (3), in the catalytic layer, the iridium source is H2IrCl6, the tin source is SnCl4, and the palladium source is PdCl2.

[0029] More specifically, in step (3), the iridium source is first dissolved in an organic solvent, stirred until completely dissolved, and then the tin source and the palladium source are added.

[0030] More specifically, in step (4), the drying temperature is 60-100°C, and the drying time is 10-20 minutes; the sintering temperature is 450-600°C, and the sintering time each time is 10-40 minutes. After the sintering is completed, the temperature is kept warm for 10-30 minutes within the same temperature range; after the insulation is completed, the titanium anode is taken out and naturally cooled to room temperature, and this is repeated 16-20 times. The thickness of the catalytic layer is about 2-3 μm.

[0031] In the above steps, step (1) is used to cut the titanium substrate into the required size and shape to meet the needs of subsequent processing and practical application, ensuring that the anode can be adapted to a specific electrolytic device or other usage scenarios. Using quartz sand with a particle size of 100-300 mesh and sandblasting at a pressure of 0.4-0.6 MPa can form a rough structure with uniform overall distribution on the surface of the titanium substrate. This rough surface increases the specific surface area of ​​the titanium substrate, which is conducive to better adhesion of the subsequent intermediate layer and catalytic layer, enhances the bonding force between the coating and the substrate, and reduces the risk of the coating falling off during use. Using 10% NaOH solution for alkaline washing and degreasing for 0.5h can effectively remove oil stains, impurities and organic pollutants on the surface of the titanium substrate. The presence of these pollutants will hinder the close bonding of the intermediate layer and catalytic layer with the titanium substrate. After removing the oil stains, the subsequent coating process can be smoothly carried out, and the quality and stability of the coating can be improved. Using hydrochloric acid with a concentration of 5%-25%, oxalic acid with a concentration of 4%-10% or sulfuric acid with a concentration of 10%-30% for etching for a time of 5-30min. The etching process not only further cleans the titanium substrate surface but also removes the surface oxide layer, exposing a fresh, active metal surface. Etching also roughens the surface microstructure, further increasing the specific surface area, providing more active sites for the attachment of the intermediate and catalytic layers, and improving the bonding strength between the coating and the substrate. Washing with pure water removes residual acid and other impurities from the etching process, ensuring a clean, contamination-free titanium substrate surface. Drying removes surface moisture, preventing it from affecting the coating's quality and performance during subsequent processing and ensuring that the intermediate and catalytic layers are evenly applied to the titanium substrate surface.

[0032] In step (2), the intermediate layer base liquid is a mixed solution of TiCl4 and TaCl5, which is applied to the surface of the pretreated titanium substrate by dipping, spraying or brushing. These metal salt solutions will decompose to form TiO2 and Ta2O5 intermediate layers during the subsequent high-temperature treatment process. The intermediate layer plays a transition and buffering role. It can improve the interface performance between the titanium substrate and the catalytic layer, enhance the bonding force between the two, and at the same time improve the stability and corrosion resistance of the anode, prevent the titanium substrate from being corroded during use, and extend the service life of the anode. Drying in an oven at 65-75°C for 10-20 minutes can remove the solvent in the intermediate layer base liquid and make the metal salt evenly distributed on the surface of the titanium substrate. Then sintering in a sintering furnace at 450-600°C for 5-30 minutes, the metal salt undergoes thermal decomposition reaction to form a dense TiO2 and Ta2O5 intermediate layer. Repeating the coating-drying-cooling steps 2-6 times can increase the thickness and density of the intermediate layer, further improving the performance and protective effect of the intermediate layer.

[0033] In step (3), the iridium source (H2IrCl6) is first dissolved in an organic solvent (a mixture of one or more of n-butanol, ethanol, ethylene glycol, isopropanol, or propanol), stirred until completely dissolved, and then the tin source (SnCl4) and palladium source (PdCl2) are added and stirred again until completely dissolved. This dissolution sequence helps ensure that the metal salts are evenly dispersed in the organic solvent, forming a total metal ion concentration of 0.3 mol·L -1 The catalytic layer is characterized by a uniform mixture of Ir, Sn, and Pd with a molar ratio of (5-6):3:(1-2). The appropriate metal ion concentration and ratio are key factors in ensuring high catalytic activity in the catalyst layer. The synergistic effect between different metals can optimize catalytic performance and improve the efficiency and selectivity of the anode in the electrocatalytic reaction.

[0034] Through step (4), the mixed solution obtained in step (3) is evenly coated on the surface of the titanium substrate with the intermediate layer obtained in step (2), so that the catalytic layer liquid can fully cover the intermediate layer, laying the foundation for the subsequent formation of a uniform catalytic layer. Drying at 60-100°C for 10-20 minutes removes the organic solvent in the catalytic layer liquid and preliminarily fixes the metal salt on the surface of the intermediate layer. Then sintering at 450-600°C for 10-40 minutes, the metal salt undergoes a thermal decomposition reaction to form a catalytic layer containing Ir, Sn, and Pd oxides. After sintering is completed, the temperature is continued to be kept within the same temperature range for 10-30 minutes, which helps to make the crystal structure of the catalytic layer more perfect and improve the stability and catalytic activity of the catalytic layer. Repeating the coating-drying-sintering process 16-20 times can increase the thickness and uniformity of the catalytic layer, further improving the catalytic performance and service life of the anode. The palladium-doped Ir-Sn oxide-coated titanium anode finally obtained has high catalytic activity, good stability and corrosion resistance, and is suitable for various electrocatalytic fields. Example

[0035] A method for preparing a high catalytic activity palladium-doped Ir-Sn oxide titanium anode comprises the following steps: (1) Pretreatment of the titanium substrate: cutting and sandblasting the titanium substrate, then alkaline washing and degreasing with 10% NaOH solution for 0.5 h, and finally etching it in a boiling 6% oxalic acid solution for 1 h. After etching, rinse with pure water to obtain the titanium substrate; (2) Preparation of the intermediate layer: dilute hydrochloric acid is used as the solvent, and a certain proportion of TiCl4 and TaCl5 are added. After fully stirring, an intermediate layer coating liquid of a certain concentration is obtained. The intermediate layer coating liquid is fully coated on the surface of the etched titanium plate, dried in an oven at a temperature of 70°C for 15 minutes, and sintered in a sintering furnace at a temperature of 490°C for 30 minutes. The coating-drying-sintering process is repeated 4 times and then used.

[0036] (3) Preparation of the noble metal oxide catalyst layer: Use a pipette to transfer 10 mL of a mixture of n-butanol and isopropanol (1:1), mix them, and stir them evenly on a magnetic stirrer to obtain a specific organic solvent. H2IrCl6 is used as the iridium source, SnCl4 is used as the tin source, and PdCl2 is used as the palladium source. The total metal ion concentration of the solution is 0.3 mol·L -1 A noble metal oxide catalyst layer was prepared at a molar ratio of iridium, tin, and palladium of 5:3:2. H₂IrCl₆ was added to the organic solvent and stirred on a magnetic stirrer for 30 minutes. SnCl₄ and PdCl₂ were then added and stirred for a further 45 minutes to obtain a palladium-doped iridium-tin oxide noble metal oxide catalyst layer. The mixture was sealed with plastic wrap and stored at room temperature.

[0037] (4) Coating and sintering: Use a water-absorbing sponge roller brush to dip an appropriate amount of the precious metal oxide catalyst layer prepared in step 3, and evenly apply it on the surface of the titanium sheet after pretreatment in step 1. Place it in an oven set at 70°C and dry for 15 minutes, then transfer it to a muffle furnace for sintering, set at 490°C for 25 minutes, and keep warm for 15 minutes. After completion, take out the sample and cool it naturally to room temperature to obtain a high catalytic activity palladium-doped iridium tin oxide coated titanium anode, the scanning electron microscope image of which is shown in FIG. Figure 2 . Example

[0038] The only difference between the preparation method in this embodiment and that in embodiment 1 is that when preparing the noble metal oxide catalyst layer, the molar ratio of iridium, tin, and palladium is 5.5:3:1.5. Example

[0039] The only difference between the preparation method in this embodiment and that in embodiment 1 is that when preparing the noble metal oxide catalyst layer, the molar ratio of iridium, tin and palladium is 6:3:1.

[0040] Comparative Example 1: The only difference between this comparative example and the preparation method in Example 1 is that this comparative example relates to a method for preparing an iridium tin oxide-coated titanium anode that is not doped with palladium, and specifically comprises the following steps: (1) Pretreatment of the titanium substrate: cutting and sandblasting the titanium substrate, then alkaline washing and degreasing with 10% NaOH solution for 0.5 h, and finally etching it in a boiling 6% oxalic acid solution for 1 h. After etching, rinse with pure water to obtain the titanium substrate; (2) Preparation of the intermediate layer: The pretreated titanium substrate surface is coated with the primer. After coating, it is kept in a high-temperature furnace to allow thermal decomposition reaction to occur on the substrate surface. After keeping in temperature for 5 to 30 minutes, it is taken out of the furnace and cooled to room temperature. The coating-keeping-cooling steps are repeated 4 times.

[0041] (3) Preparation of the noble metal oxide catalyst layer: Use a pipette to transfer 10 mL of a mixture of n-butanol and isopropanol (1:1), mix them, and stir them evenly on a magnetic stirrer to obtain a specific organic solvent. H2IrCl6 is used as the iridium source, SnCl4 is used as the tin source, and the total metal ion concentration of the solution is 0.3 mol·L -1 Prepare a noble metal oxide catalyst layer with a molar ratio of iridium to tin of 7:3. Add H₂IrCl₆ to the above organic solvent and stir on a magnetic stirrer for 30 minutes. Then add SnCl₄ and continue stirring for 45 minutes to obtain a noble metal oxide catalyst layer of iridium-tin oxide. Seal with plastic wrap and store at room temperature.

[0042] (3) Coating and sintering: Use a water-absorbing sponge roller brush to dip an appropriate amount of the precious metal oxide catalyst layer prepared in step 3, and evenly apply it on the surface of the titanium sheet after pretreatment in step 1. Place it in an oven set at 70°C and dry for 15 minutes, then transfer it to a muffle furnace for sintering, set at 490°C for 25 minutes, keep warm for 15 minutes, and then take out the sample and let it cool naturally to room temperature.

[0043] Performance testing: 1. Slot voltage test The cell pressure test was performed on the coated titanium anodes prepared in Examples 1 to 3 of the present invention and Comparative Example 1. The method is as follows: the prepared coated titanium anode and the titanium cathode were placed in a simulated copper electrodeposition electrolyte (H2SO4 180gL -1 ,CuSO445gL -1 ), the electrolysis experiment was carried out by DC power supply, the electrolyte temperature was 65℃, the anode current density was 5Acm -2 , electrode spacing is 3.3 cm, electrode area is 1 cm 2 , and monitor the cell pressure at the beginning of electrolysis.

[0044] 2. Accelerated life test The coated titanium anodes prepared in Examples 1 to 3 of the present invention and Comparative Example 1 were subjected to accelerated life tests. The method was as follows: the prepared coated titanium anodes and titanium cathodes were placed in a 0.5M sulfuric acid electrolyte. The electrolysis experiment was carried out using a DC power supply. The electrolyte temperature was 65°C and the anode current density was 5Acm -2 , electrode spacing is 3.3 cm, electrode area is 1 cm 2 , continuously monitor its cell voltage. When the cell voltage exceeds 5V, the anode is considered to have failed and the accelerated life results are recorded.

[0045] 3. Film adhesion test The film adhesion test is carried out using an automatic scratch tester. The test conditions are as follows: Detection mode: Acoustic emission Loading load: 100N Loading method: One-way continuous loading Scratch length: 6mm Loading rate: 60Nmin -1 The results of the bonding strength test are the critical load values ​​at which the coating begins to break, and the results are shown in Table 1. Table 1. Performance comparison of examples and comparative examples

[0046] In summary, the performance of the palladium-doped iridium tin oxide-coated titanium anode prepared by the present invention was tested, and 0.5 mol / L sulfuric acid solution was used as the electrolyte to perform an electrochemical impedance spectroscopy (EIS) test on the samples prepared in Examples 1 to 3 and Comparative Example 1. There is a close relationship between electrochemical impedance spectroscopy (EIS) and electrocatalytic activity. EIS cannot directly quantify electrocatalytic activity, but it can provide key information related to activity. In EIS, the charge transfer resistance (Rct) reflects the ease of charge transfer in the electrocatalytic reaction. The smaller the Rct, the faster the charge transfer, which usually means a higher electrocatalytic activity. Therefore, Rct is one of the important parameters for evaluating electrocatalytic activity.

[0047] Test conditions: frequency is 100kHz~10Hz, amplitude is 5mV.

[0048] The results show that the present invention introduces the relatively cheap precious metal element palladium, and the defect effect caused by the doping of heteroatoms will affect the original electronic structure of iridium tin oxide, thereby obtaining higher electrocatalytic activity. Figure 3 The smaller the diameter of the semicircle in the AC impedance diagram, the smaller the charge transfer resistance at the interface between the electrode and the electrolyte, which is more conducive to charge transfer.

[0049] Compared with the samples in Comparative Example 1, Examples 1-3 showed significantly reduced charge transfer resistance and significantly improved electrocatalytic performance. As can be seen from Examples 1-3 and the Comparative Example, the lower the palladium content, the shorter the lifespan. Furthermore, in Example 3, the low palladium content weakened the synergistic effect, thus shortening the service life of the titanium anode prepared in Example 3.

[0050] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the invention can be embodied in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the invention is defined by the appended claims rather than the foregoing description, and it is intended that all variations that come within the meaning and range of equivalents of the claims be embraced therein.

Claims

1. A high catalytic activity palladium-doped Ir-Sn oxide titanium anode, characterized in that: The following components are included, arranged in sequence: Base: Made of titanium or titanium alloy; Middle layer: contains TiO2 and Ta2O5; Catalytic layer: containing oxides of Ir, Sn, and Pd; The molar ratio of Ir, Sn, and Pd in ​​the catalyst layer is (5-6):3:(1-2), and the total metal ion concentration is 0.3 mol·L -1 .

2. A method for preparing the high catalytic activity palladium-doped Ir-Sn oxide titanium anode according to claim 1, characterized in that: The following steps are involved: (1) Pretreatment of the titanium substrate: cutting, sandblasting, etching, cleaning and drying the titanium substrate to obtain a pretreated titanium substrate; (2) Preparation of the intermediate layer: coating the intermediate layer base liquid on the surface of the titanium substrate pretreated in step (1), drying it in a high-temperature furnace, and repeating the coating → drying → cooling steps several times after cooling; (3) Preparation of catalytic layer liquid: Dissolve the iridium source, tin source, and palladium source in an organic solvent and stir until completely dissolved to form a total metal ion concentration of 0.3 mol·L -1 A mixed solution, wherein the molar ratio of Ir:Sn:Pd is (5-6):3:(1-2); (4) Preparation of catalytic layer: The mixed solution obtained in step (3) is evenly coated on the surface of the titanium substrate obtained in step (2), taken out after drying and sintering, and naturally cooled to room temperature, and then the above-mentioned coating → drying → sintering process is repeated to obtain a titanium anode with a palladium-doped Ir-Sn oxide coating.

3. The method for preparing a high catalytic activity palladium-doped Ir-Sn oxide titanium anode according to claim 2, characterized in that: In step (1), the titanium substrate is cut and sandblasted, then alkaline washed with 10% NaOH solution for degreasing for 0.5 h, and then etched in a boiling etching solution. After etching, it is washed with pure water and dried to obtain the pretreated titanium substrate.

4. The method for preparing a high catalytic activity palladium-doped Ir-Sn oxide titanium anode according to claim 3, characterized in that: In step (1), the etching treatment uses hydrochloric acid with a concentration of 5% to 25%, oxalic acid with a concentration of 4% to 10%, or sulfuric acid with a concentration of 10% to 30%, and the etching time is 5 to 30 minutes.

5. The method for preparing a palladium-doped Ir-Sn oxide titanium anode with high catalytic activity according to claim 4, characterized in that: In step (1), in the titanium substrate pretreatment, sandblasting is performed using quartz sand with a particle size of 100 to 300 meshes and a sandblasting pressure of 0.4 to 0.6 MPa.

6. The method for preparing a palladium-doped Ir-Sn oxide titanium anode with high catalytic activity according to claim 2, characterized in that: In step (2), the intermediate layer base liquid is a mixed solution of TiCl4 and TaCl5. After the intermediate layer base liquid is applied, it is dried in an oven at a temperature of 65-75°C for 10-20 minutes, and then placed in a sintering furnace at a temperature of 450-600°C for 5-30 minutes. After cooling, the coating → drying → cooling steps are repeated 2-6 times; In step (2), the intermediate layer primer is applied by dipping, spraying or brushing.

7. The method for preparing a palladium-doped Ir-Sn oxide titanium anode with high catalytic activity according to claim 2, characterized in that: In step (3), the organic solvent is a mixture of one or more of n-butanol, ethanol, ethylene glycol, isopropanol or propanol.

8. The method for preparing a palladium-doped Ir-Sn oxide titanium anode with high catalytic activity according to claim 2, characterized in that: In step (3), in the catalytic layer, the iridium source is H2IrCl6, the tin source is SnCl4, and the palladium source is PdCl2.

9. The method for preparing a palladium-doped Ir-Sn oxide titanium anode with high catalytic activity according to claim 2, characterized in that: In step (3), the iridium source is first dissolved in an organic solvent, stirred until completely dissolved, and then the tin source and palladium source are added.

10. The method for preparing a palladium-doped Ir-Sn oxide titanium anode with high catalytic activity according to claim 6, characterized in that: In step (4), the drying temperature is 60-100°C, and the drying time is 10-20 minutes; the sintering temperature is 450-600°C, and the sintering time each time is 10-40 minutes. After sintering, the titanium anode is kept warm for 10-30 minutes within the same temperature range. After the heat preservation is completed, the titanium anode is taken out and naturally cooled to room temperature, and repeated 2-4 times.

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