A doped diamond-ruthenium oxide coupling electrode and its preparation method and application

Abstract

The present invention discloses a doped diamond-ruthenium oxide coupling electrode and a preparation method and application thereof. The doped diamond-ruthenium oxide coupling electrode comprises a substrate and an electrode working layer arranged on the surface of the substrate. The electrode working layer is a double-layer film structure, which comprises a ruthenium oxide film layer and a doped diamond film layer from bottom to top, and doped diamond particles are added to the ruthenium oxide film layer. This coupling electrode combines the advantages of oxide-coated electrodes and doped diamond electrodes, and has a heterojunction effect, good electrical conductivity, corrosion resistance and mechanical strength, and can be used for electrocatalytic wastewater degradation, chemical battery positive electrode lightweight grid, electrochemical synthesis, electrical signal detection, tail gas treatment and other related electrochemical fields.

Description

Technical Field

[0001] The invention discloses a doped diamond-ruthenium oxide coupling electrode and a preparation method and application thereof, belonging to the technical field of electrode preparation. Background Art

[0002] Doped diamond has a very wide electrochemical window, a very high oxygen evolution potential, a very low background current, excellent chemical stability, surface inertness and weak adsorption, and is a research hotspot in the field of environmental electrochemistry. In the field of ecological environment, it is often used to treat difficult-to-biodegrade organic wastewater with high concentration, high salinity, high ammonia nitrogen, strong acidity and alkalinity, and is called the "ideal anode material."

[0003] Electrocatalytic oxidation is known as an "environmentally friendly" technology. It uses electrons as catalysts and can effectively treat wastewater containing organic pollutants at room temperature and pressure. With the continuous industrialization of electrocatalytic oxidation, it is becoming possible to apply electrocatalytic oxidation technology to large-scale field applications. The most critical factor in electrocatalytic oxidation is the selection of anode materials. Ruthenium dioxide has good electrocatalytic oxidation characteristics and has a good oxidative degradation effect on the treatment of organic wastewater.

[0004] However, although the doped diamond electrode has an extremely high oxygen evolution potential, its conductivity is poorer than that of metal or oxide films, and there are problems such as low efficiency and high energy consumption during use. In addition, under the existing process technology, the doped diamond electrode based on foam or particles is prone to uneven coverage or even falling off during the preparation process. Summary of the invention

[0005] In view of the deficiencies in the prior art, the object of the present invention is to provide a doped diamond-ruthenium oxide coupled electrode with uniform film coverage, excellent conductivity and electrocatalytic degradation performance, as well as a preparation method and application thereof.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] The present invention discloses a doped diamond-ruthenium oxide coupling electrode, which comprises a substrate and an electrode working layer arranged on the surface of the substrate, wherein the electrode working layer is a double-layer film structure, which comprises, from bottom to top, a ruthenium oxide film layer and a doped diamond film layer, wherein the ruthenium oxide film layer comprises a ruthenium oxide matrix and doped diamond particles uniformly dispersed in the ruthenium oxide matrix.

[0008] The inventor unexpectedly discovered that the ruthenium oxide film has excellent electrical conductivity, but due to its low oxygen evolution potential, it cannot oxidize difficult-to-degrade organic matter with high oxidation potential. However, when a doped diamond film is set on its surface, it can form a PN junction with the doped diamond film, thereby strengthening the electron separation in a constant electric field and improving the current efficiency, thereby obtaining a coupled electrode with the most excellent catalytic performance.

[0009] In addition, the introduction of doped diamond particles into the ruthenium oxide film layer can, on the one hand, improve the problem of thermal expansion coefficient mismatch between the double-layer films, and on the other hand, easily form OC bonds with the doped diamond film layer. Through the above two effects, the double-layer film not only has excellent bonding performance, but also further improves the conductivity. In addition, it can also be used as the crystal nucleus for the subsequent CVD preparation of the doped diamond film layer to enhance the bonding force between the double-layer films.

[0010] In a preferred embodiment, the substrate is selected from one of metals nickel, niobium, tantalum, zirconium, copper, titanium, cobalt, tungsten, molybdenum, chromium, iron or one of their alloys; or the substrate is selected from ceramic Al 2 O 3 、ZrO 2 、SiC、Si 3 N 4 , BN, B 4 C, AlN, TiB 2 、TiN、WC、Cr 7 C 3 、Ti 2 GeC、Ti 2 AlC and Ti 2 AlN、Ti 3 SiC 2 、Ti 3 G JZ 2 、Ti 3 AlC 2 、Ti 4 AlC 3 、BaPO 3 One of the above or the doped ceramics therein; or the substrate is selected from one of the composite materials composed of the above metals and ceramics, or the substrate is selected from diamond or Si; preferably ceramics.

[0011] The base shape includes at least one of powder, granular, cylindrical, cylindrical, and flat plate;

[0012] The substrate structure is selected from at least one of a three-dimensional continuous network structure, a two-dimensional continuous mesh structure and a two-dimensional closed flat plate structure.

[0013] In the present invention, since the ruthenium oxide film layer is firstly provided on the substrate, and since the ruthenium oxide film layer is a ceramic phase, the problem of insufficient bonding strength between the doped diamond film layer and the ceramic substrate can be avoided.

[0014] In a preferred solution, the thickness of the ruthenium oxide film layer is 10-120 μm, preferably 80-100 μm, the thickness of the doped diamond film layer is 5-20 μm; the particle size of the doped diamond particles is 0.1-20 μm, preferably 15-20 μm.

[0015] The inventors have found that controlling the thickness of the ruthenium oxide film layer and the doped diamond film layer within the above range makes it easier to form OC bonds and intermediates, thereby improving the bonding strength of the two films. In addition, with the coordination of the above thicknesses, the conductive performance of the final coupled electrode is optimal.

[0016] In a preferred solution, the volume fraction of the doped diamond particles in the ruthenium oxide film layer is 0.1%-50%, preferably 10-30%.

[0017] In a preferred embodiment, in the ruthenium oxide film layer, the molar ratio of ruthenium to oxygen is 1:2-8.

[0018] In a preferred solution, the ruthenium oxide film matrix contains carbon doping, and the mass fraction of the carbon element in the ruthenium oxide film matrix is ​​1%-20%, preferably 3-8%.

[0019] The inventors have found that carbon doping of the ruthenium oxide film can form a carbon bridge or a carbide intermediate product between the oxide coating and the doped diamond film, further improving the bonding force between the film layers.

[0020] In a preferred embodiment, the doping element in the doped diamond film layer is selected from at least one of boron, nitrogen, phosphorus and lithium, preferably boron; and the doping method includes one or more combinations of constant doping, multi-layer variable doping and gradient doping.

[0021] In a preferred embodiment, the mass fraction of the doping element in the doped diamond film layer is 2‰-10‰.

[0022] The inventors found that the doping elements can react with the metal elements in the oxide coating to generate intermediate products, thereby further improving the bonding strength between the double-layer films.

[0023] In a preferred embodiment, the doped diamond film layer forms a full coating, a half coating, or a selective coating on the surface of the ruthenium oxide film layer, preferably a full coating.

[0024] In a preferred embodiment, the doping element in the doped diamond particles is selected from at least one of boron, nitrogen, phosphorus and lithium, preferably boron; and the doping method includes one or more combinations of constant doping, multi-layer variable doping and gradient doping.

[0025] In a preferred embodiment, the mass fraction of the doping element in the doped diamond particles is 2‰-10‰.

[0026] The invention discloses a method for preparing a doped diamond-ruthenium oxide coupling electrode. Firstly, a ruthenium oxide film layer is prepared on the surface of a substrate by an electrodeposition method or a composite thermal decomposition method, and then a doped diamond film layer is prepared by chemical vapor deposition to obtain a double-layer film coupling electrode.

[0027] The preferred solution is that the process of preparing the ruthenium oxide film layer by the electrodeposition method is as follows: the metal is used as the anode and the substrate is used as the cathode, and the electrodeposition is carried out in an electrolyte, and then a heat treatment is carried out. The electrolyte contains the following components: 1-10 g / L of ruthenium trichloride, 3-10 g / L of potassium chloride, 1-5 g / L of hydrochloric acid, and 0.1-50 g / L of doped diamond particles; the parameters of the electrodeposition are: the current density is 200-1000 A / m 2 The temperature of the electrolyte is 35-60°C, and the electrodeposition time is 10-120 min; the temperature of the heat treatment is 100°C-300°C, the heat treatment time is 1-5 h, the heating rate is 5°C-10°C / min, the vacuum degree is 1-100 Pa, and the argon atmosphere flow rate is 20-50 sccm.

[0028] Further preferably, the electrolyte further contains carbonate, the mass fraction of the carbonate in the electrolyte is 1%-20%, and the carbonate is selected from one or more of sodium carbonate, potassium carbonate and sodium bicarbonate.

[0029] The preferred scheme is that the process of preparing the ruthenium oxide active film layer by the composite thermal decomposition method is: dissolving 50-150g / L of ruthenium trichloride and 10-50g / L of hydrated ruthenium oxide in an alcohol solvent to obtain a mixed solution, adding doped diamond particles to the mixed solution and mixing evenly to obtain a slurry, wherein the mass ratio of diamond particles to the mixed solution is 0.05-250:1000; the slurry is evenly arranged on the substrate by film forming, and then placed in an oven at 50-80°C for 10-30min, and then placed in a resistance furnace for calcining at 450-650°C for 10-30min, and the operation is repeated 8-20 times, and the last calcination is carried out in a resistance furnace for 1-2h.

[0030] Further preferably, carbon powder is added into the slurry, and the mass fraction of the carbon powder in the slurry is 1%-20%.

[0031] Further preferably, the film forming method is selected from one or more of dipping, spin coating, roll coating, spray coating, and brush coating.

[0032] Further preferably, the alcohol solvent is selected from one of anhydrous n-butanol, anhydrous ethanol, anhydrous ethylene glycol and anhydrous glycerol.

[0033] The preferred scheme is that the process of preparing the doped diamond film layer by chemical vapor deposition is as follows: placing the obtained substrate material in a chemical deposition furnace, the mass flow ratio of the introduced gas is hydrogen: methane: doping gas source = 100: (1-5): (01.-2.5), the growth pressure is 2-5Kpa, the growth temperature is 600-950°C, the number of growths is 1-4 times, and after each growth, the substrate is taken out, the positive and negative sides are replaced, and then the growth is continued. The single growth time is 1-20h, and the doping gas source is selected from at least one of ammonia, phosphine, and borane.

[0034] The invention discloses an application of a doped diamond-ruthenium oxide coupling electrode, and the doped diamond-ruthenium oxide coupling electrode is applied to the fields of electrochemical synthesis, electrochemical sewage purification, electrochemical detection and electrochemical biosensor.

[0035] Beneficial Effects

[0036] The present invention provides a doped diamond-ruthenium oxide coupling electrode, which includes a substrate and an electrode working layer disposed on the surface of the substrate. The electrode working layer is a double-layer film structure, which includes a ruthenium oxide film layer and a doped diamond film layer from bottom to top, and doped diamond particles are added to the ruthenium oxide film layer. The inventor unexpectedly discovered that the ruthenium oxide film layer has excellent electrical conductivity, but due to its low oxygen evolution potential, it cannot oxidize difficult-to-degrade organic matter with high potential. However, when a doped diamond film layer is disposed on its surface, a PN junction can be formed with the doped diamond film layer, thereby strengthening the separation of electrons in a constant electric field and improving the current efficiency, thereby obtaining a coupling electrode with the best catalytic performance.

[0037] The present invention effectively solves the problem in the existing BDD preparation technology that BDD is severely attenuated and cannot completely cover the substrate. After the BDD falls off, there is still an oxide coating inside to play an electrolytic role; BDD has an extremely high oxygen evolution potential, which can make up for the problem that the existing oxide coating electrode cannot oxidize high potential difficult-to-degrade organic matter;

[0038] In addition, in order to address the problem of insufficient bonding between BDD and the ceramic substrate, an intermediate layer oxide coating is introduced. On the one hand, the oxide coating and the substrate are both in ceramic phase and have good bonding strength. On the other hand, by adding doped diamond particles during the preparation of the oxide coating, the problem of thermal expansion coefficient mismatch between the double-layer films is improved, thereby improving the bonding strength between the double-layer films. DETAILED DESCRIPTION

[0039] Example 1

[0040] The silicon carbide ceramic is used as a substrate, the substrate is ultrasonically cleaned, and an active ruthenium oxide film layer is prepared by an electrodeposition method. The specific process is: metal titanium is used as an anode, and the silicon carbide substrate is used as a cathode to be placed in an electrolyte for electrodeposition, and then heat treatment is performed. The electrolyte contains the following components: 5g / L of ruthenium trichloride, 6g / L of potassium chloride, and 3g / L of hydrochloric acid. Boron-doped diamond particles with a particle size of 20μm are added to the electrolyte, wherein the boron doping concentration is 5‰, and the solid-liquid mass volume ratio of the diamond particles to the electrolyte is 20g:1L; the parameters of the electrodeposition are: the current density is 600A / m 2 The temperature of the electrolyte is 50°C, and the electrodeposition time is 90 min; the temperature of the heat treatment is 200°C, the heat treatment time is 3 h, the heating rate is 5°C / min, the vacuum degree is 20 Pa, and the argon atmosphere flow rate is 20 sccm.

[0041] A substrate containing a ruthenium oxide active film layer is placed in a chemical vapor deposition furnace: the mass flow ratio of the introduced gas is hydrogen: methane: doping gas source = 100:2:0.5, the growth pressure is 2Kpa, the growth temperature is 800°C, the number of growths is 4 times, and after each growth, the substrate is taken out, replaced with the front and back sides, and then the growth is continued. The single growth time is 10 hours, and borane is selected as the doping gas source.

[0042] The boron-doped diamond-ruthenium oxide double-layer film coupling electrode prepared in the above Example 1 has a thickness of 90 μm for the ruthenium oxide film layer and a thickness of 15 μm for the doped diamond film layer. The obtained boron-doped diamond-ruthenium oxide film layer is firm and does not fall off when scratched. The volume fraction of the doped diamond particles in the ruthenium oxide film layer is 20%.

[0043] The prepared boron-doped diamond-ruthenium oxide coupled electrode was packaged, and a stainless steel electrode was used as the negative electrode. 1L of electrolyte Na with an initial concentration of 100 mg / L was prepared. 2 SO 4 The concentration of 0.1 mol / L reactive orange X-GN simulated dye wastewater was adjusted to Ph 3 with sulfuric acid, and placed on a magnetic stirrer with a speed of 200 r / min. The current density was maintained at 100 mA / cm during the degradation process. 2 After 2 hours of degradation, the chromaticity removal rate of the dye reached 97%, and the degradation was basically complete.

[0044] Example 2

[0045] Taking zirconia ceramic as the substrate, the substrate was ultrasonically cleaned, and the ruthenium oxide active film layer was prepared by a composite thermal decomposition method. The specific process was as follows: 100 g / L ruthenium trichloride and 15 g / L hydrated ruthenium oxide were dissolved in anhydrous ethanol to make a slurry, and boron-doped diamond particles with a particle size of 20 μm were added to the slurry, wherein the boron concentration was 3‰, and the mass ratio of diamond particles to the slurry was 100 g:1000 g. The slurry was evenly prepared on the substrate by brushing, and then placed in an oven at 80°C for 20 minutes, and then placed in a resistance furnace for baking at 500°C for 30 minutes. The operation was repeated 20 times, and the last time it was baked in a resistance furnace for 2 hours.

[0046] A substrate containing a ruthenium oxide active film layer is placed in a chemical vapor deposition furnace: the mass flow ratio of the introduced gas is hydrogen: methane: doping gas source = 100:2:0.2, the growth pressure is 2Kpa, the growth temperature is 800°C, the number of growths is 4 times, and after each growth, the substrate is taken out, replaced with the front and back sides, and then the growth is continued. The single growth time is 10 hours, and borane is selected as the doping gas source.

[0047] The boron-doped diamond-ruthenium oxide double-layer film coupling electrode prepared in the above Example 2 has a thickness of 95 μm for the ruthenium oxide film layer and a thickness of 17 μm for the doped diamond film layer. The obtained boron-doped diamond-ruthenium oxide film layer is firm and does not fall off when scratched. The volume fraction of the doped diamond particles in the ruthenium oxide film layer is 20%.

[0048] The prepared boron-doped diamond-ruthenium oxide coupled electrode was packaged, and a stainless steel electrode was used as the negative electrode. 1L of electrolyte Na with an initial concentration of 100 mg / L was prepared. 2 SO 4 The simulated dye wastewater with a concentration of 0.1 mol / L of reactive orange X-GN was placed on a magnetic stirrer and the speed was adjusted to 200 r / min. The current density was maintained at 100 mA / cm during the degradation process. 2 After 2 hours of degradation, the chromaticity removal rate of the dye reached 99%, and the degradation was basically complete.

[0049] Example 3

[0050] The other conditions are the same as those in Example 2, except that carbon doping is performed during the preparation process, and 5% by mass of carbon powder is added to the slurry. The thickness of the obtained ruthenium oxide active film layer is 98 μm, and the thickness of the boron-doped diamond film layer is 18 μm. The obtained boron-doped diamond-ruthenium oxide film layer is firm and does not fall off when scratched. Keeping other conditions unchanged, the dye is degraded for 1.5 hours, and the chromaticity removal rate reaches 99%, which is basically complete degradation.

[0051] Comparative Example 1

[0052] The other conditions were the same as those in Example 1, except that the deposition time was 200 min when the ruthenium oxide active film was prepared by the electrodeposition method. The thickness of the obtained ruthenium oxide active film was 150 μm. After chemical vapor deposition coating, the obtained doped diamond film was obviously detached, and the degradation effect was far inferior to that in Example 1.

[0053] Comparative Example 2

[0054] The other conditions were the same as those in Example 1, except that no doped diamond particles were added when the ruthenium oxide active film layer was prepared by the electrodeposition method. After chemical vapor deposition coating, the obtained doped diamond film layer fell off when scratched, the film layer had insufficient bonding strength, the heterojunction effect was poor, and the degradation effect was far inferior to that in Example 1.

[0055] Comparative Example 3

[0056] The other conditions were the same as those in Example 2, except that the number of brushing was 3 times. The thickness of the obtained ruthenium oxide active film layer was 5 μm, the film layer had poor density, and the degradation effect was far inferior to that in Example 2.

Claims

1. A doped diamond-ruthenium oxide coupling electrode, characterized in that: The doped diamond-ruthenium oxide coupling electrode comprises a substrate and an electrode working layer arranged on the surface of the substrate, wherein the electrode working layer is a double-layer film structure, which comprises a ruthenium oxide film layer and a doped diamond film layer from bottom to top, wherein the ruthenium oxide film layer comprises a ruthenium oxide matrix and doped diamond particles uniformly dispersed in the ruthenium oxide matrix; the thickness of the ruthenium oxide film layer is 10-120 μm, and the thickness of the doped diamond film layer is 5-20 μm; the preparation method of the doped diamond-ruthenium oxide coupling electrode comprises first preparing a ruthenium oxide film layer on the surface of the substrate by an electrodeposition method or a composite thermal decomposition method, and then preparing a doped diamond film layer by chemical vapor deposition to obtain a double-layer film coupling electrode; The process of preparing the ruthenium oxide film layer by the electrodeposition method is as follows: using the metal as the anode and the substrate as the cathode to be placed in an electrolyte for electrodeposition, and then heat treatment is performed to obtain the film layer. The electrolyte contains the following ingredients: 1-10 g / L of ruthenium trichloride, 3-10 g / L of potassium chloride, 1-5 g / L of hydrochloric acid, and 0.1-50 g / L of doped diamond particles; the parameters of the electrodeposition are: the current density is 200-1000 A / m 2 , the temperature of the electrolyte is 35-60°C, the electrodeposition time is 10-120min; the temperature of the heat treatment is 100°C-300°C, the heat treatment time is 1-5h, the heating rate is 5°C-10°C / min, the vacuum degree is 1-100pa, and the argon atmosphere flow rate is 20-50sccm; The process of preparing the ruthenium oxide active film layer by the composite thermal decomposition method is as follows: 50-150 g / L of ruthenium trichloride and 10-50 g / L of hydrated ruthenium oxide are dissolved in an alcohol solvent to obtain a mixed solution, doped diamond particles are added into the mixed solution and mixed evenly to obtain a slurry, wherein the mass ratio of the diamond particles to the mixed solution is 0.05-250:1000; the slurry is evenly arranged on a substrate by film making, and then placed in an oven for baking at 50-80°C for 10-30 minutes, and then placed in a resistance furnace for baking at 450-650°C for 10-30 minutes, and the operation is repeated 8-20 times, and the last baking is carried out in a resistance furnace for 1-2 hours to obtain the slurry.

2. The doped diamond-ruthenium oxide coupling electrode according to claim 1, characterized in that: The substrate is selected from one of the metals nickel, niobium, tantalum, zirconium, copper, titanium, cobalt, tungsten, molybdenum, chromium, iron or one of their alloys; or the substrate is selected from one of the ceramics Al2O3, ZrO2, SiC, Si3N4, BN, B4C, AlN, TiB2, TiN, WC, Cr7C3, Ti2GeC, Ti2AlC and Ti2AlN, Ti3SiC2, Ti3GeC2, Ti3AlC2, Ti4AlC3, BaPO3; or the substrate is selected from one of the composite materials composed of the above metals and ceramics, or the substrate is selected from diamond or Si; The shape of the substrate is selected from at least one of powder, granular, cylindrical, cylindrical, and flat; The substrate structure is selected from at least one of a three-dimensional continuous network structure, a two-dimensional continuous mesh structure and a two-dimensional closed flat plate structure.

3. A doped diamond-ruthenium oxide coupling electrode according to claim 1 or 2, characterized in that: The particle size of the doped diamond particles is 0.1 μm-20 μm; the volume fraction of the doped diamond particles in the ruthenium oxide film layer is 0.1%-50%.

4. A doped diamond-ruthenium oxide coupling electrode according to claim 1 or 2, characterized in that: In the ruthenium oxide film layer, the molar ratio of ruthenium to oxygen is 1:2-8; The ruthenium oxide film matrix contains carbon doping, and the mass fraction of the carbon element in the ruthenium oxide film matrix is ​​1%-20%.

5. A doped diamond-ruthenium oxide coupling electrode according to claim 1 or 2, characterized in that: The doping element in the doped diamond film layer is selected from at least one of boron, nitrogen and phosphorus, and the doping method includes one or more combinations of constant doping, multi-layer variable doping and gradient doping; The mass fraction of the doping element in the doped diamond film layer is 2‰-10‰; The doped diamond film layer forms a full coating, a half coating, or a selective coating on the surface of the ruthenium oxide film layer; The doping element in the doped diamond particles is selected from at least one of boron, nitrogen, phosphorus and lithium, and the doping method includes one or more combinations of constant doping, multi-layer variable doping and gradient doping; The mass fraction of the doping element in the doped diamond particles is 2‰-10‰.

6. A method for preparing a doped diamond-ruthenium oxide coupling electrode according to any one of claims 1 to 5, characterized in that: First, a ruthenium oxide film layer is prepared on the substrate surface by an electrodeposition method or a composite thermal decomposition method, and then a doped diamond film layer is prepared by chemical vapor deposition to obtain a double-layer film coupling electrode; The process of preparing the ruthenium oxide film layer by the electrodeposition method is as follows: using the metal as the anode and the substrate as the cathode to be placed in an electrolyte for electrodeposition, and then heat treatment is performed to obtain the film layer. The electrolyte contains the following ingredients: 1-10 g / L of ruthenium trichloride, 3-10 g / L of potassium chloride, 1-5 g / L of hydrochloric acid, and 0.1-50 g / L of doped diamond particles; the parameters of the electrodeposition are: the current density is 200-1000 A / m 2 , the temperature of the electrolyte is 35-60°C, the electrodeposition time is 10-120min; the temperature of the heat treatment is 100°C-300°C, the heat treatment time is 1-5h, the heating rate is 5°C-10°C / min, the vacuum degree is 1-100pa, and the argon atmosphere flow rate is 20-50sccm; The process of preparing the ruthenium oxide active film layer by the composite thermal decomposition method is as follows: 50-150 g / L of ruthenium trichloride and 10-50 g / L of hydrated ruthenium oxide are dissolved in an alcohol solvent to obtain a mixed solution, doped diamond particles are added into the mixed solution and mixed evenly to obtain a slurry, wherein the mass ratio of the diamond particles to the mixed solution is 0.05-250:1000; the slurry is evenly arranged on a substrate by film making, and then placed in an oven for baking at 50-80°C for 10-30 minutes, and then placed in a resistance furnace for baking at 450-650°C for 10-30 minutes, and the operation is repeated 8-20 times, and the last baking is carried out in a resistance furnace for 1-2 hours to obtain the slurry.

7. The method for preparing a doped diamond-ruthenium oxide coupling electrode according to claim 6, characterized in that: The electrolyte further contains carbonate, the mass fraction of the carbonate in the electrolyte is 1%-20%, and the carbonate is selected from one or more of sodium carbonate, potassium carbonate, and sodium bicarbonate; Carbon powder is also added into the slurry, and the mass fraction of the carbon powder in the slurry is 1%-20%.

8. The method for preparing a doped diamond-ruthenium oxide coupling electrode according to claim 7, characterized in that: The process of preparing a doped diamond film layer by chemical vapor deposition is as follows: placing a substrate containing a ruthenium oxide active film layer in a chemical deposition furnace, introducing a gas with a mass flow ratio of hydrogen:methane:doping gas source = 100:(1-5):(01.-2.5), a growth pressure of 2-5Kpa, a growth temperature of 750-950°C, and a growth frequency of 1-4 times. After each growth, the substrate is taken out, and the positive and negative sides are replaced before continuing the growth. The single growth time is 1-20 hours, and the doping gas source is selected from at least one of ammonia, phosphine, and borane.

9. The use of a doped diamond-ruthenium oxide coupling electrode according to any one of claims 1 to 5, characterized in that: The doped diamond-ruthenium oxide coupling electrode is applied to the fields of electrochemical synthesis, electrochemical sewage purification, electrochemical detection and electrochemical biosensor.