A tantalum-penetrated gradient interlayer titanium-based metal oxide electrode and a preparation method thereof

Abstract

The present application belongs to the field of electrochemistry, and particularly relates to a titanium-based metal oxide electrode containing a double-layer glow plasma tantalum permeation gradient intermediate layer and a preparation method thereof. The main structure of the electrode comprises a titanium base at the bottom, a mixed metal oxide electrocatalytic layer on the surface, and a double-layer glow plasma tantalum permeation gradient intermediate layer between the two. The electrode preparation method is to prepare a tantalum permeation gradient alloy layer on the surface of a pretreated titanium base by a double-layer glow plasma alloying method, and then prepare a mixed metal oxide electrocatalytic coating on the tantalum permeation intermediate layer by a thermal decomposition method. The tantalum permeation gradient intermediate layer not only has good conductivity and adhesion, but also can significantly enhance the corrosion resistance and stability of the electrode, effectively prevent the passivation of the titanium base, so that the electrode can still have a long service life under a large current density and a strong oxygen evolution environment, meet the needs of engineering, and have a wide application prospect.

Description

Technical fields:

[0001] This invention belongs to the field of electrochemical technology, specifically relating to a titanium-based metal oxide electrode containing a double-layer glow discharge plasma-diffused tantalum gradient intermediate layer and its preparation method, which is applicable to electrochemical engineering. Background technology:

[0002] Titanium-based metal oxide electrodes are electrodes constructed by preparing a mixed metal oxide coating on a titanium substrate, primarily composed of RuO2, IrO2, SnO2, TiO2, and Ta2O5. They are used in electrochemical engineering applications such as electroplating, hydrometallurgy, impressed current cathodic protection, electrochemical oxidation, wastewater treatment, chlor-alkali industry, water electrolysis, and seawater antifouling. Depending on the composition of the mixed metal oxide coating, they are suitable for different fields. Titanium-based metal oxide electrodes are among the most widely used electrode materials commercially. A key technical challenge in their practical application is extending electrode lifespan, especially in high-current-density, strong oxygen evolution environments. Ordinary titanium-based metal oxide electrodes cannot maintain high electrocatalytic activity while achieving a long service life.

[0003] Coatings with RuO2 as the main active component exhibit high electrocatalytic activity under oxygen evolution and chlorine evolution environments. However, they readily generate RuO4 in acidic media, leading to continuous dissolution of the oxide coating and a short service life. Therefore, RuO2-based metal oxide coating electrodes are primarily used in chlorine evolution environments. IrO2 is a relatively ideal active component for oxygen evolution electrode coatings, mainly used in impressed current cathodic protection, electroplating, and hydrometallurgy. PbO2 and SnO2 have high oxygen evolution overpotentials and can generate a large number of hydroxyl radicals, making them suitable for wastewater treatment and electrochemical oxidation. A single active component often cannot fully realize the material's potential. By mixing it with other oxides, electrode performance can be improved. Examples include Ti / RuO2-TiO2 electrodes, Ti / IrO2-Ta2O5 electrodes, and Ti / SnO2-Pb electrodes. Among these, the IrO2-Ta2O5 electrode exhibits superior performance under strong oxygen evolution conditions.

[0004] Existing titanium-based metal oxide electrodes fail after a period of operation, with a lifespan that fails to meet practical requirements, especially when operating at high current densities in strongly acidic environments. Research has revealed that passivation of the substrate during electrolysis, forming a non-conductive TiO2 passivation film, is the primary cause of electrode failure. Specifically, the passivation film formed between the substrate and the surface conductive metal oxide layer increases contact resistance and cell voltage, and reduces the adhesion between the substrate and the active coating, accelerating the peeling of the surface metal oxide coating and leading to rapid electrode failure. Adding an intermediate layer between the substrate and the active coating can solve this problem and extend the electrode's lifespan. A high-performance intermediate layer can serve as a sub-layer of the metal oxide coating. On one hand, its surface physicochemical structure can influence the surface roughness and cracking degree of the metal oxide coating, thereby affecting the electrocatalytic activity of the electrode. On the other hand, during electrolysis, it can prevent active oxygen from reaching the titanium substrate and inhibit the formation of non-conductive TiO2, thus extending the electrode's lifespan.

[0005] Chinese Patent 201910187710.2 discloses a composite interlayer for titanium-based oxide electrodes, comprising MnO2, CeO2, SnO2, and Sb2O3, with MnO2 and CeO2 doped into SnO2 and Sb2O3 in solid solution form. This metal oxide electrode, with the composite oxide of Mn, Ce, Sn, and Sb as the interlayer, is mainly used for the electrocatalytic oxidative degradation of phenol. Chinese Patent 202110298113.4 discloses a method for preparing an intermediate-layer modified titanium-based lead oxide electrode, comprising the following steps: dissolving tin salt and cesium salt or tin salt and antimony salt in organic solvent A to obtain a precursor solution; dropping the precursor solution onto a titanium substrate material, drying, and sintering to obtain a Cs2O-SnO2 or Sb2O3-SnO2 interlayer attached to the titanium substrate material, thus forming a Ti / Cs2O-SnO2 or Ti / Sb2O3-S... nO2 electrode; In an acidic solution, β-PbO2 is electrodeposited onto the outer layer of a Ti / Cs2O-SnO2 or Ti / Sb2O3-SnO2 electrode to obtain an intermediate layer modified titanium-based lead oxide electrode Ti / Cs2O-SnO2 / PbO2 or Ti / Sb2O3-SnO2 / PbO2; It uses Cs2O-SnO2 or Sb2O3-SnO2 as the intermediate layer, with a PbO2 layer electrodeposited on the surface, mainly used for the degradation of antibiotic wastewater. Chinese Patent 200810139149.2 discloses a metal oxide coated electrode, comprising a metal substrate and a metal oxide coating, with an intermediate layer between the metal substrate and the metal oxide coating. The intermediate layer is prepared by impregnating nanoparticles of a titanium-based metal ceramic compound with a solution containing platinum group metal compounds to obtain an intermediate layer coating solution, which is then coated onto the metal substrate and dried, followed by oxidative thermal decomposition to obtain the product; it is used in chlor-alkali, water electrolysis, fuel cells, wastewater treatment, and other fields. Chinese Patent 202010936706.4 discloses an IrO2-Ta2O5 anode with a TiN nanotube interlayer. The anode uses Ti as a substrate, with an IrO2-Ta2O5 nanocoating prepared on the surface, and a TiN nanotube interlayer prepared between the IrO2-Ta2O5 nanocoating and the Ti substrate. While the above-mentioned electrodes using metal oxides or ceramic compounds as interlayers can improve electrode performance, their protection of the titanium substrate is weak, making it difficult to meet the requirements of high current density under harsh conditions in strongly acidic environments. Furthermore, they also suffer from the need for precious metals and complex preparation processes. Chinese Patent 201310153286.2 discloses a method for preparing a metal oxide anode containing a cold-sprayed tantalum interlayer. First, a tantalum interlayer is prepared on a titanium substrate using an advanced cold-spraying method. Then, a mixed metal oxide electrocatalytic coating is prepared on top of this tantalum interlayer. Chinese Patent 201110044764.7 discloses a method for preparing a metal oxide electrode containing a tantalum interlayer, which includes three process steps: substrate pretreatment, tantalum interlayer preparation, and oxide coating preparation.Technical literature: Journal of Applied Electrochemistry, 1998(28):245-250, discloses a metal oxide electrode with a tantalum interlayer prepared by molten salt electroplating. The electrode performance, especially the electrode life, of the tantalum interlayer metal oxide prepared by the above method is significantly improved. However, the cold spraying technology results in serious waste of tantalum powder, the high-temperature molten salt electroplating process is complex and not environmentally friendly, and the interlayer prepared by thermal decomposition has poor adhesion to the substrate and is prone to peeling after long-term use. Therefore, it is necessary to research and develop a new high-performance electrode material to further improve electrode performance and meet the needs of long-life operation under harsh conditions of high current density. Summary of the Invention:

[0006] The purpose of this invention is to overcome the shortcomings of existing technologies and to develop and design a tantalum-diffused gradient intermediate layer titanium-based metal oxide electrode and its preparation method. By using a double-layer glow discharge plasma tantalum gradient intermediate layer, the performance of metal oxide anode materials is significantly improved.

[0007] To achieve the above objectives, the present invention relates to a titanium-based metal oxide electrode with a tantalum gradient interlayer, the main structure of which includes a titanium substrate at the bottom, a mixed metal oxide electrocatalytic layer on the surface, and a double-layer glow plasma tantalum gradient interlayer between the two. The double-layer glow plasma tantalum gradient interlayer can significantly improve the performance of the metal oxide anode material, making the electrode material more cost-effective.

[0008] The titanium matrix includes industrially pure titanium;

[0009] The thickness of the double-layer glow discharge plasma-diffused tantalum gradient intermediate layer is 5-150 μm, consisting of an upper pure tantalum layer and a lower gradient alloy layer. The thickness of the pure tantalum layer is not less than 0.1 μm, and the optimal thickness is 1-6 μm.

[0010] The mixed metal oxide electrocatalytic layer is a binary or multi-component metal oxide composite coating, wherein the mixed metal oxide is composed of one or more of electroactive IrO2, RuO2, Pt or other noble metal oxides and one or more of non-noble metal oxides such as Ta2O5, SnO2, SiO2, MnO2, ZrO2.

[0011] The double-layer glow discharge plasma tantalum gradient intermediate layer involved in this invention is an alloy layer formed by diffusion tantalum diffusion. Tantalum atoms are deposited on the surface of the titanium substrate and diffuse inward. The tantalum content in the diffusion layer gradually decreases and the titanium content gradually increases from the pure tantalum layer downward. The tantalum diffusion intermediate layer is metallurgically bonded to the titanium substrate, which significantly improves the bonding force and can provide effective protection for the titanium substrate. It avoids the formation of microcracks between the mixed metal oxide electrocatalytic layer and the titanium substrate caused by passivation of the titanium substrate by active oxygen, which would lead to coating peeling.

[0012] This invention relates to a method for preparing a tantalum-diffused gradient intermediate layer titanium-based metal oxide electrode. The method involves preparing a tantalum-diffused gradient alloy layer on a pretreated titanium substrate using a double-layer glow discharge plasma alloying method, followed by thermal decomposition to prepare a mixed metal oxide electrocatalytic coating on the tantalum-diffused intermediate layer. The specific process includes three steps: pretreatment of the titanium substrate, preparation of the double-layer glow discharge plasma tantalum-diffused intermediate layer, and preparation of the mixed metal oxide electrocatalytic layer.

[0013] (1) Pretreatment of titanium matrix

[0014] First, the titanium substrate is cleaned with hot alkaline water or organic solvent to remove surface oil.

[0015] Then, the surface of the titanium substrate is mechanically ground and polished to remove surface defects;

[0016] Finally, the titanium substrate was etched with an aqueous solution of oxalic acid with a mass percentage concentration of 10-20 wt% at a temperature of 75℃-95℃ for 1-2 hours to remove the oxide film on the surface and obtain a uniform and rough surface.

[0017] (2) Preparation of a double-layer glow discharge plasma-doped tantalum interlayer

[0018] First, in the working chamber, an anode, a titanium substrate (cathode), and a tantalum target (source) are set up, and a DC adjustable high voltage power supply is connected between the anode and the cathode and between the anode and the source.

[0019] Then, the working chamber is evacuated and filled with inert gas to reach the working pressure;

[0020] Finally, two adjustable DC high-voltage power supplies are connected to generate glow discharges between the anode and cathode and between the anode and source, forming a double-layer glow discharge. The ions generated by ionization bombard the surface of the titanium substrate, activating it and raising its temperature. The particles (ions, atoms, electrons or particle clusters) sputtered from the source surface are adsorbed and deposited onto the more active titanium substrate surface under the action of electric and magnetic fields, and diffuse into the interior of the titanium substrate at high temperature, forming a tantalum-infiltrated intermediate layer.

[0021] The inert gas includes argon, with a pressure of 35-50 Pa; the tantalum target is pure tantalum with a tantalum content of 99.95% or higher; the process parameters for double-layer glow discharge plasma alloying are: voltage of 900-950V for the tantalum target, voltage of 400-450V for the titanium substrate, spacing between the tantalum target and the titanium substrate of 20-25mm, processing temperature of 800℃-900℃, and holding time of 1-4h.

[0022] (3) Preparation of mixed metal oxide electrocatalytic layer

[0023] First, the surface of the tantalum-diffused intermediate layer is etched with HF (hydrogen fluoride) at a mass percentage concentration of 5-15% for 10-30 seconds, then removed and placed in anhydrous ethanol for later use.

[0024] Etching can remove the slightly oxidized tantalum oxide on the outermost surface of the tantalum-infiltrated interlayer, thereby enhancing the conductivity of the tantalum-infiltrated interlayer.

[0025] Then, the prepared precursor solution is applied to the tantalum-infiltrated intermediate layer by brushing or spraying, and then dried, sintered and cooled in sequence to obtain the mixed metal oxide electrocatalytic layer.

[0026] Finally, the coating-drying-sintering-cooling process was repeated several times until the mixed metal oxide electrocatalytic layer reached the set loading, thus obtaining a titanium-based metal oxide electrode with a tantalum-infiltrated intermediate layer.

[0027] The precursor solution is obtained by dissolving one or more of the following substances—ruthenium chloride, chloroiridic acid, titanium tetrachloride, and tantalum pentachloride—in an alcohol solution, with a metal concentration of 0.1–1 mol·L⁻¹. -1 The drying temperature is 80℃-120℃, and the time is 8-15 min; the sintering temperature is 400℃-600℃, and the time is 10-20 min; the final sintering time is 1-2 h.

[0028] Compared with existing technologies, the titanium-based metal oxide electrode of this invention consists of a titanium substrate, a double-layer glow discharge plasma tantalum infiltration gradient interlayer, and a mixed metal oxide electrocatalytic layer. The preparation method involves first forming a tantalum infiltration gradient interlayer that is metallurgically bonded to the pretreated titanium substrate using a double-layer glow discharge plasma tantalum infiltration process. Then, a mixed metal oxide electrocatalytic layer is prepared using a thermal decomposition method, resulting in a titanium-based metal oxide electrode containing the double-layer glow discharge plasma tantalum infiltration interlayer. This tantalum infiltration gradient interlayer not only possesses excellent conductivity and adhesion but also significantly enhances the electrode's corrosion resistance and stability. Furthermore, it effectively prevents passivation of the titanium substrate, enabling the electrode to maintain a long service life even under high current density and strong oxygen evolution environments, meeting engineering requirements. It has broad application prospects in electroplating, hydrometallurgy, impressed current cathodic protection, electrochemical oxidation, wastewater treatment, and electrolytic seawater antifouling, and is particularly suitable for applications requiring high current density and strong oxygen evolution environments. Attached image description:

[0029] Figure 1 This is a schematic diagram of the structure of the tantalum-doped intermediate layer metal oxide electrode involved in this invention.

[0030] Figure 2 The diagram shows the polarization curves of the experimental electrode and the control electrode involved in this invention.

[0031] Figure 3The figures show the cyclic voltammetry curves of the experimental electrode and the control electrode involved in this invention at different scan rates.

[0032] Figure 4 This is a schematic diagram showing the change of cell voltage over time during enhanced electrolysis of the experimental electrode and the control electrode involved in this invention. Detailed implementation method:

[0033] The present invention will be further described below with reference to the embodiments and accompanying drawings.

[0034] Example 1:

[0035] This embodiment relates to an environmentally friendly method for preparing a titanium-based metal oxide electrode. The specific process is as follows:

[0036] First, the titanium substrate is pretreated: TA2 pure titanium plate is immersed in 1M NaOH aqueous solution and degreased at 90℃ for 1 hour. Then, it is placed in 10wt% oxalic acid aqueous solution and etched at 80℃ for 2 hours to obtain the pretreated titanium substrate.

[0037] Then, a double-layer glow discharge plasma tantalum infiltration intermediate layer was prepared on the pretreated titanium substrate: the pretreated TA2 pure titanium plate and tantalum target were placed in a double glow discharge plasma surface alloying device, with the TA2 pure titanium plate as the cathode and the tantalum target as the source electrode. The tantalum content in the tantalum target exceeded 99.95%. The vacuum was evacuated to the ultimate vacuum degree and filled with argon gas at a pressure of 35 Pa. The voltage of the tantalum target was set to 900 V, the voltage of the TA2 pure titanium plate was set to 400 V, the distance between the tantalum target and the TA2 pure titanium plate was 20 mm, the treatment temperature was 800 °C, and the holding time was 2 h. The tantalum infiltration intermediate layer was prepared by the double-layer glow discharge plasma alloying method.

[0038] The obtained tantalum infiltration intermediate layer consists of two layers. The first layer is a pure Ta layer located at the top with a thickness of about 1 μm. The second layer is a gradient alloy layer with a thickness of about 18 μm. As the depth increases, the tantalum content in the alloy layer decreases and the titanium content increases. A metallurgical bond is formed between the tantalum infiltration intermediate layer and the titanium substrate.

[0039] Finally, a mixed metal oxide electrocatalytic layer was prepared on the double-layer glow discharge plasma-infiltrated tantalum intermediate layer: the surface of the tantalum-infiltrated intermediate layer was etched with HF with a mass percentage concentration of 10% for 10 seconds and then removed and placed in anhydrous ethanol for later use.

[0040] Chloroirilic acid and tantalum pentachloride were dissolved in n-butanol and hydrochloric acid and stirred for 3 min to obtain a metal concentration of 0.3 mol·L⁻¹. -1 The precursor solution contains iridium and tantalum in a molar ratio of 7:3;

[0041] The precursor solution was brushed onto the etched tantalum-infiltrated intermediate layer, dried at 120°C for 10 min, and then sintered at 500°C for 15 min. After removal, it was naturally cooled to room temperature to obtain the mixed metal oxide electrocatalytic layer.

[0042] Repeat the coating, drying, sintering, and cooling processes until the oxide electrocatalytic layer is loaded with 7 g·m -2 The final sintering temperature was 500℃ for 1 hour to obtain a titanium-based metal oxide electrode containing a tantalum gradient intermediate layer.

[0043] The double-layer glow discharge plasma-diffused tantalum gradient interlayer not only boasts a significantly faster fabrication speed compared to conventional alloying techniques but also exhibits high corrosion resistance, effectively preventing passivation of the titanium substrate and significantly extending the lifespan of the metal oxide anode. The physicochemical structure of the tantalum-diffused interlayer itself influences the dispersion and crystallinity of active particles in the surface-mixed metal oxide electrocatalytic layer, thereby enhancing the electrocatalytic activity of the electrode. This tantalum-diffused gradient interlayer enables the electrode to possess high electrocatalytic activity, excellent stability, and a long service life, thus meeting the requirements for long-term operation under harsh conditions.

[0044] Example 2:

[0045] This embodiment relates to the performance testing of a titanium-based metal oxide electrode, using the titanium-based metal oxide electrode with a tantalum-infiltrated interlayer prepared in Example 1 as the experimental electrode, and the titanium-based iridium-tantalum metal oxide anode as the control electrode.

[0046] The preparation process of the control electrode is as follows:

[0047] First, the TA2 pure titanium plate is sandblasted and then cleaned with alkaline water to remove grease.

[0048] Then, it is placed in a 10% oxalic acid aqueous solution boiled for 2 hours for acid etching to remove the passivation film on the surface and obtain a uniform rough surface. It is then repeatedly washed with deionized water and anhydrous ethanol and placed in anhydrous ethanol for later use.

[0049] Finally, a mixed metal oxide electrocatalytic layer was prepared on a pretreated TA2 pure titanium plate using the method of Example 1 to obtain a control electrode.

[0050] Test the performance of the experimental electrode and the control electrode:

[0051] I. The electrocatalytic performance of the electrode was evaluated using polarization curves, with a polarization value of 0.33 mV·s. -1 The scan rate was measured in the range of 1.0V-1.5V (vs. SCE), the auxiliary electrode was a platinum sheet, the reference electrode was a saturated calomel electrode, and the test solution was 0.5mol / L sulfuric acid;

[0052] Obtain as Figure 2 As shown in the anodic polarization curves, under the same potential conditions, the current density of the experimental electrode is greater than that of the control electrode, indicating that the tantalum-dopated interlayer improves the electrocatalytic activity of the experimental electrode.

[0053] II. Cyclic voltammetry was performed using the experimental and control electrodes in a 0.5 mol / L sulfuric acid aqueous solution. The scan rate was 10 mV / s–100 mV / s, and the scan range was 0.6 V–0.8 V (vs. SCE). The results are as follows: Figure 3 As shown, through the equation: and Obtain the volt-ampere charge outside the electrode, inside the electrode, and the total volt-ampere charge, where, This refers to the volt-ampere charge outside the electrode. This represents the volt-ampere charge inside the electrode. Let v be the total volt-ampere charge of the electrode, v be the scan rate, and k1 and k2 be constants. The results are shown in the table below.

[0054] electrode <![CDATA[q tot * / mF·cm -2 ]]> <![CDATA[q out * / mF·cm -2 ]]> <![CDATA[q in * / mF·cm -2 ]]> experimental electrodes 175.40 22.51 152.89 contrast electrode 123.15 19.46 103.69

[0055] It is evident that the various volt-ampere charges of the experimental electrode are all higher than those of the control electrode, especially the internal and total volt-ampere charges, which are significantly increased. The volt-ampere charge reflects the number of active sites of the electrode participating in the electrochemical reaction. According to the table above, the number of active sites of the experimental electrode is significantly increased, especially the number of internal active sites. Due to the significant increase in the number of active sites in the tantalum-impregnated interlayer electrode, the experimental electrode exhibits higher electrocatalytic activity.

[0056] III. The stability of the experimental and control electrodes was tested using an enhanced electrolysis life test in a 1 mol / L sulfuric acid aqueous solution at 40℃, at a concentration of 3 A / cm. 2 Electrolysis is performed at a current density of 10V, with the electrode as the working electrode and the titanium plate as the cathode. The gap between the working electrode and the cathode is 2cm. When the cell voltage increases to 10V, the electrode fails.

[0057] The results are as follows Figure 4 As shown, the lifespan of the control electrode is only 348 hours, while that of the experimental electrode is 779 hours. The enhanced electrolysis lifespan of the experimental electrode is increased several times, indicating that the tantalum gradient intermediate layer bonded to the matrix metallurgy significantly extends the lifespan of the experimental electrode.

Claims

1. A tantalum-diffused gradient intermediate layer titanium-based metal oxide electrode, characterized in that, The main structure includes a titanium substrate and a mixed metal oxide electrocatalytic layer, as well as a double-layer glow discharge plasma infiltrating tantalum gradient intermediate layer between the two. The double-layer glow discharge plasma infiltrating tantalum gradient intermediate layer is composed of a pure tantalum layer and a gradient alloy layer, and the thickness of the pure tantalum layer is not less than 0.1 μm.

2. The tantalum-diffused gradient intermediate layer titanium-based metal oxide electrode according to claim 1, characterized in that, The titanium matrix includes industrially pure titanium.

3. The tantalum-diffused gradient intermediate layer titanium-based metal oxide electrode according to claim 2, characterized in that, The thickness of the intermediate layer of the double-layer glow discharge plasma tantalum gradient layer is 5-150 μm, which is an alloy layer formed by diffusion tantalum diffusion. The thickness of the pure tantalum layer is 1-6 μm. The tantalum content in the diffusion layer gradually decreases and the titanium content gradually increases.

4. The tantalum-diffused gradient intermediate layer titanium-based metal oxide electrode according to claim 3, characterized in that, The mixed metal oxide electrocatalytic layer is a binary or multi-component metal oxide composite coating, wherein the mixed metal oxide is composed of one or more electroactive noble metal oxides and one or more non-noble metal oxides.

5. A method for preparing a titanium-based metal oxide electrode with a tantalum-diffused gradient intermediate layer, characterized in that, First, a tantalum-diffused gradient alloy layer is prepared on the surface of a titanium substrate using a double-layer glow discharge plasma alloying method. Then, a mixed metal oxide electrocatalytic coating is prepared on the tantalum-diffused intermediate layer using a thermal decomposition method.

6. The method for preparing a tantalum-diffused gradient intermediate layer titanium-based metal oxide electrode according to claim 5, characterized in that, When preparing a double-layer glow discharge plasma-doped tantalum interlayer: First, in the working chamber, an anode, a titanium substrate, and a tantalum target are set up, and a DC adjustable high voltage power supply is connected between the anode and the cathode and between the anode and the source. Then, the work chamber is evacuated and filled with inert gas; Finally, two adjustable DC high-voltage power supplies are connected to generate glow discharges between the anode and cathode and between the anode and source, forming a double-layer glow discharge. The ions generated by ionization bombard the surface of the titanium substrate, activating it and raising its temperature. The particles sputtered from the source surface are adsorbed and deposited onto the surface of the titanium substrate under the action of electric and magnetic fields, and diffuse into the interior of the titanium substrate at high temperature, forming a tantalum-infiltrated intermediate layer.

7. The method for preparing a tantalum-diffused gradient intermediate layer titanium-based metal oxide electrode according to claim 6, characterized in that, When preparing the mixed metal oxide electrocatalytic layer: First, the surface of the tantalum-infiltrated intermediate layer is etched with HF at a mass percentage concentration of 5-15% for 10-30 seconds, then removed and placed in anhydrous ethanol for later use. Then, the precursor solution was coated onto the tantalum-diffused intermediate layer, and then dried, sintered and cooled in sequence to obtain the mixed metal oxide electrocatalytic layer; Finally, the coating-drying-sintering-cooling process is repeated several times until the mixed metal oxide electrocatalytic layer reaches the set loading.

8. A method for preparing a tantalum-diffused gradient intermediate layer titanium-based metal oxide electrode according to any one of claims 5-7, characterized in that, Before preparing the tantalum gradient alloy layer and the mixed metal oxide electrocatalytic coating, the titanium substrate is pretreated. The specific process is as follows: First, clean the titanium substrate with hot alkaline water or organic solvent; Then, the surface of the titanium substrate is mechanically ground and polished; Finally, the titanium substrate was etched for 1-2 hours using an aqueous solution of oxalic acid with a mass percentage concentration of 10-20 wt% at a temperature of 75℃-95℃.

9. The method for preparing a tantalum-diffused gradient intermediate layer titanium-based metal oxide electrode according to claim 6, characterized in that, The inert gas includes argon with a pressure of 35-50 Pa; the tantalum target is pure tantalum with a tantalum content of 99.95% or higher; the process parameters for double-layer glow discharge plasma alloying are: voltage of tantalum target of 900-950V, voltage of titanium substrate of 400-450V, spacing between tantalum target and titanium substrate of 20-25mm, treatment temperature of 800℃-900℃, and holding time of 1-4h.

10. The method for preparing a tantalum-diffused gradient intermediate layer titanium-based metal oxide electrode according to claim 7, characterized in that, The precursor solution is obtained by dissolving one or more of ruthenium chloride, chloroiridic acid, titanium tetrachloride, and tantalum pentachloride in an alcohol solution, with a metal concentration of 0.1-1 mol·L⁻¹. -1 The drying temperature is 80℃-120℃, and the time is 8-15 min; the sintering temperature is 400℃-600℃, and the time is 10-20 min; the final sintering time is 1-2 h.

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