Preparation method of Ti / Magni / BDD environment catalytic electrode for sewage treatment

Abstract

The invention discloses a preparation method of a Ti / Magnli / BDD environmental catalytic electrode for sewage treatment, which comprises the following steps: taking Ti as an electrode substrate, taking a Magnli-phase low-valence titanium oxide as a middle transition layer, and taking BDD as a surface catalytic layer as an electrode of a sandwich structure. The purpose of adopting the Ti / Magni electrode as the substrate electrode is that BDD can be smoothly crystallized to form a film on the surface of the substrate electrode; and Ti is adopted as an electrode substrate which is cheaper than Nb, and a large-size electrode is easier to obtain compared with a wafer.

Description

Technical Field

[0001] The invention relates to the technical field of catalytic electrodes, and in particular to a method for preparing a Ti / Magnèli / BDD environmental catalytic electrode for sewage treatment. Background Art

[0002] With the rapid development of chemical, pharmaceutical, pesticide and other industries, the types and quantities of toxic and harmful pollutants in industrial wastewater have increased rapidly. Traditional biological treatment technology is difficult to make industrial wastewater containing toxic organic pollutants meet the discharge standards, which poses a serious threat to environmental water bodies and human health. It is urgent to treat wastewater to meet the standards.

[0003] In recent years, electrocatalytic oxidation technology has attracted continuous attention from scholars at home and abroad as a water treatment method for toxic and harmful pollutants. Electrocatalytic oxidation can be carried out at room temperature and pressure. It can easily change the electric field at the solid-liquid interface to effectively control the direction and rate of the reaction. It can improve the biodegradability of wastewater and convert toxic organic matter into low-toxic and harmless substances. It also has the advantages of simple operation, mild reaction conditions, and no secondary pollution. Therefore, electrocatalytic oxidation technology has a good application prospect. The core of electrocatalytic oxidation technology is electrocatalytic electrode materials. BDD (boron-doped diamond) has the special sp3 bond structure of diamond and its conductivity after doping, which gives BDD excellent electrochemical properties, making BDD a new type of efficient multifunctional electrode electrocatalytic electrode material.

[0004] Commonly used titanium-based electrodes such as graphite electrodes, titanium-based lead dioxide electrodes, titanium-based tin dioxide electrodes, and DSA electrodes have significant defects in water treatment applications of toxic and harmful pollutants due to factors such as narrow electrochemical potential window, low stability, and low current density of the electrode. The currently popular BDD (boron-doped diamond) electrode cannot be widely used in sewage treatment projects due to the constraints of factors such as the type, price, and size of the electrode substrate. Based on this, the present invention further improves it. Summary of the invention

[0005] In view of the defects of the prior art, the purpose of the present invention is to provide a method for preparing a Ti / Magnèli / BDD environmental catalytic electrode for sewage treatment to solve the problems raised in the above background technology.

[0006] The present invention solves the technical problem by adopting the following technical solution: The present invention provides a method for preparing a Ti / Magnèli / BDD environmental catalytic electrode for sewage treatment, comprising the following steps: It is a sandwich structure electrode, with Ti as the electrode matrix, Magnèli phase low-valent titanium oxide as the intermediate transition layer, and BDD as the surface catalyst layer; The method comprises the following steps: Ti substrate pretreatment step, Magnèli phase low-valent titanium oxide intermediate transition layer preparation step and Ti / Magnèli / BDD environmental catalytic electrode preparation step; The Ti substrate pretreatment step comprises sandblasting with 10-900 mesh corundum and steaming with 1-90% concentration of oxalic acid; The step of preparing the Magnèli phase low-valent titanium oxide intermediate transition layer is to adjust the working gas and use an atmospheric plasma spraying device to prepare the Magnèli phase low-valent titanium oxide intermediate transition layer by plasma spraying the Magnèli phase low-valent titanium oxide powder to obtain a Ti / Magnèli electrode; The step of preparing the Ti / Magnèli / BDD environmental catalytic electrode is to use the prepared Ti / Magnèli electrode as a base electrode and obtain a BDD surface catalytic layer by processing with a CatCVD device.

[0007] Preferably, in the step of preparing the Magnèli phase low-valent titanium oxide intermediate transition layer, the main working gas is argon or nitrogen, and the secondary working gas is hydrogen or helium.

[0008] Preferably, in the step of preparing the intermediate transition layer of the Magnèli phase low-valent titanium oxide, the atmospheric plasma spraying equipment adjusts the working gas range: main gas pressure and flow rate: argon 0.4-0.65 MPa and nitrogen 1.2-3 m³ / h, secondary gas pressure and flow rate: hydrogen 0.25-0.4 MPa and helium 0-1.2 m³ / h.

[0009] Preferably, in the step of preparing the Magnèli phase low-valent titanium oxide intermediate transition layer, the Magnèli phase low-valent titanium oxide powder is a compound with the chemical formula TinO2n-1.

[0010] Preferably, in the step of preparing the Magnèli phase low-valent titanium oxide intermediate transition layer, the Magnèli phase low-valent titanium oxide powder is Ti4O7 or a mixture of Ti4O7 and Ti5O9 with a content of ≥10% and a particle size of 1 to 1600 μm.

[0011] Preferably, in the step of preparing the Magnèli phase low-valent titanium oxide intermediate transition layer, the Magnèli phase low-valent titanium oxide powder is plasma sprayed by atmospheric plasma spraying equipment to prepare the Magnèli phase low-valent titanium oxide intermediate transition layer, the thickness of the intermediate transition layer is 1 to 10000 μm, and the coating porosity is 1 to 50%, to obtain a Ti / Magnèli electrode; Magnèli phase low-valent titanium oxide is easily oxidized in high temperature ≥600℃ atmospheric environment. In order to avoid excessive oxidation and ensure that the content of Ti4O7 or the mixture of Ti4O7 and Ti5O9 in the intermediate transition layer meets the standard, the flow rate of the reducing working gas or the inert protective gas should be controlled; the thickness of the intermediate transition layer is mainly controlled by the movement speed of the spray gun; the porosity of the coating is controlled by controlling the hydrogen flow rate. The hydrogen flow rate is 1L / min, the porosity is 8.23%; the hydrogen flow rate is 8L / min, the porosity is 2.55%.

[0012] Preferably, in the CatCVD hot wire chemical vapor deposition method step, the reaction gas is: CH4; H2; B(OCH3)3, B2H6 or boron compound gas.

[0013] Preferably, in the CatCVD step, the CatCVD equipment parameters are: gas ratio CH4 flow rate 1.0~50.0sccm, H2 flow rate 200.0sccm, B(OCH3)3 flow rate 1.0~50.0sccm; catalytic hot wire material W or Ta, catalytic hot wire temperature is 200~2000℃, and substrate temperature ≤1000℃.

[0014] To operate CatCVD equipment, it is necessary to set the process parameters: power, catalytic hot wire temperature, gas flow rate; select the appropriate B / C, reaction chamber pressure, deposition time, etc. The thickness of the surface catalytic layer is mainly controlled by the deposition time. The purity of the surface catalytic layer is mainly controlled by controlling the gas ratio and the pressure in the reaction chamber. Compared with traditional CVD equipment (such as DCPJCVD equipment, MPCVD equipment, etc.), CatCVD equipment has the following advantages: lower substrate temperature (as low as 300°C) protects the Magnèli phase low-valent titanium oxide in the intermediate transition layer, providing a guarantee for the production of Ti / Magnèli / BDD environmental catalytic electrodes; large-area thin film deposition is achieved, making it easier to realize the engineering application of electrodes; gas source molecules can be decomposed at any gas pressure, so that the deposition of thin films has greater freedom; gas source utilization is higher, and the cost of producing electrodes is lower. The purpose of using Ti / Magnèli electrodes as substrate electrodes: BDD can be smoothly crystallized and formed into films on the surface of this substrate electrode; using Ti as the electrode substrate is cheaper than Nb and easier to obtain large-sized electrodes than wafers.

[0015] The prepared Ti / Magnèli electrode is used as a base electrode, and a BDD surface catalytic layer is obtained by processing with a CatCVD device. The thickness of the surface catalytic layer is ≥1 nm, thereby obtaining a Ti / Magnèli / BDD environmental catalytic electrode.

[0016] The present invention also provides a Ti / Magnèli / BDD environmental catalytic electrode, which is prepared according to the preparation method.

[0017] The present invention also provides a sewage treatment method, which uses the Ti / Magnèli / BDD environmental catalytic electrode as an electrode to perform electrochemical treatment of sewage.

[0018] A method for preparing a Ti / Magnèli / BDD environmental catalytic electrode for sewage treatment, which is a sandwich structure electrode, which uses Ti (titanium) as an electrode matrix, Magnèli phase low-valent titanium oxide as an intermediate transition layer, and BDD (boron-doped diamond film) as a surface catalytic layer. The method comprises the following steps: a Ti substrate pretreatment step, a Magnèli phase low-valent titanium oxide intermediate transition layer preparation step and a Ti / Magnèli / BDD environmental catalytic electrode preparation step, wherein the Ti (metal titanium) substrate pretreatment step comprises sandblasting with 10-900 mesh corundum and steaming with 1-90% concentration of oxalic acid; the Magnèli phase low-valent titanium oxide intermediate transition layer preparation step comprises adjusting the working gas and preparing the Magnèli phase low-valent titanium oxide powder by plasma spraying with an atmospheric plasma spraying device; and the Ti / Magnèli / BDD environmental catalytic electrode preparation step comprises using the prepared Ti / Magnèli electrode as a substrate electrode and obtaining a BDD (boron-doped diamond film) surface catalytic layer by CatCVD (hot wire chemical vapor deposition) equipment.

[0019] Compared with the prior art, the present invention has the following beneficial effects: The present invention breaks through the constraints of the current BDD electrode and is easy to carry out economical and large-scale production. Traditional CVD equipment, MPCVD (microwave plasma method) equipment: expensive equipment, difficult to expand the effective deposition area (maximum electrode size <350mm); DCPJCVD (direct current plasma jet method) equipment: expensive equipment, high investment, difficult process control, easy to cause thermal damage to the substrate. CatCVD (hot wire chemical vapor deposition method) equipment has the following characteristics: low substrate temperature (as low as 300℃) protects the Magnèli phase low-valent titanium oxide in the intermediate transition layer, providing a guarantee for the production of Ti / Magnèli / BDD environmental catalytic electrodes; large-area thin film deposition (maximum electrode size >1200mm) is achieved, making it easier to realize the engineering application of electrodes; gas source molecules can be decomposed at any gas pressure, so that the deposition of thin films has greater freedom; gas source utilization rate is higher (more than twice the gas source utilization rate of traditional equipment), the cost of producing electrodes is lower, and it has the ability to be applied industrially. The purpose of using Ti / Magnèli electrode as the substrate electrode is that BDD can be crystallized and formed into a film on the surface of the substrate electrode; using Ti as the electrode substrate is cheaper than Nb and easier to obtain large-sized electrodes than wafers. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a cross-sectional view of the Ti / Magnèli / BDD environmental catalytic electrode; Figure 2 is a scanning electron microscope image of the Ti / Magnèli electrode; FIG3 is a scanning electron microscope image of the Ti / Magnèli / BDD environmental catalytic electrode; Figure 4 shows the cyclic voltammetry curve of the Ti / Magnèli / BDD environmental catalytic electrode. DETAILED DESCRIPTION

[0021] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0022] A method for preparing a Ti / Magnèli / BDD environmental catalytic electrode for sewage treatment in this embodiment includes the following steps: It is a sandwich structure electrode, with Ti as the electrode matrix, Magnèli phase low-valent titanium oxide as the intermediate transition layer, and BDD as the surface catalyst layer; The method comprises the following steps: Ti substrate pretreatment step, Magnèli phase low-valent titanium oxide intermediate transition layer preparation step and Ti / Magnèli / BDD environmental catalytic electrode preparation step; The Ti substrate pretreatment step comprises sandblasting with 10-900 mesh corundum and steaming with 1-90% concentration of oxalic acid; The step of preparing the Magnèli phase low-valent titanium oxide intermediate transition layer is to adjust the working gas and use an atmospheric plasma spraying device to prepare the Magnèli phase low-valent titanium oxide intermediate transition layer by plasma spraying the Magnèli phase low-valent titanium oxide powder to obtain a Ti / Magnèli electrode; The step of preparing the Ti / Magnèli / BDD environmental catalytic electrode is to use the prepared Ti / Magnèli electrode as a base electrode and obtain a BDD surface catalytic layer by processing with a CatCVD device.

[0023] In the step of preparing the Magnèli phase low-valent titanium oxide intermediate transition layer of this embodiment, the main working gas is argon or nitrogen, and the secondary working gas is hydrogen or helium.

[0024] In the preparation step of the Magnèli phase low-valent titanium oxide intermediate transition layer of this embodiment, the atmospheric plasma spraying equipment adjusts the working gas range: main gas pressure and flow rate: argon 0.4~0.65 MPa and nitrogen 1.2~3 m³ / h, secondary gas pressure and flow rate: hydrogen 0.25~0.4 MPa and helium 0~1.2 m³ / h.

[0025] In the step of preparing the Magnèli phase low-valent titanium oxide intermediate transition layer of this embodiment, the Magnèli phase low-valent titanium oxide powder is a compound with the chemical formula TinO2n-1.

[0026] In the step of preparing the Magnèli phase low-valent titanium oxide intermediate transition layer of this embodiment, the Magnèli phase low-valent titanium oxide powder is Ti4O7 or a mixture of Ti4O7 and Ti5O9 with a content of ≥10% and a particle size of 1 to 1600 μm.

[0027] Preferably, in the step of preparing the Magnèli phase low-valent titanium oxide intermediate transition layer, the Magnèli phase low-valent titanium oxide powder is plasma sprayed by atmospheric plasma spraying equipment to prepare the Magnèli phase low-valent titanium oxide intermediate transition layer, the thickness of the intermediate transition layer is 1 to 10000 μm, and the coating porosity is 1 to 50%, to obtain a Ti / Magnèli electrode; Magnèli phase low-valent titanium oxide is easily oxidized in high temperature ≥600℃ atmospheric environment. In order to avoid excessive oxidation and ensure that the content of Ti4O7 or the mixture of Ti4O7 and Ti5O9 in the intermediate transition layer meets the standard, the flow rate of the reducing working gas or the inert protective gas should be controlled; the thickness of the intermediate transition layer is mainly controlled by the movement speed of the spray gun; the porosity of the coating is controlled by controlling the hydrogen flow rate. The hydrogen flow rate is 1L / min, the porosity is 8.23%; the hydrogen flow rate is 8L / min, the porosity is 2.55%.

[0028] In the CatCVD hot wire chemical vapor deposition method of this embodiment, the reaction gas is: CH4; H2; B(OCH3)3, B2H6 or boron compound gas.

[0029] In the CatCVD step of this embodiment, the CatCVD equipment parameters are: gas ratio CH4 flow rate 1.0~50.0sccm, H2 flow rate 200.0sccm, B(OCH3)3 flow rate 1.0~50.0sccm; catalytic hot wire material W or Ta, catalytic hot wire temperature is 200~2000℃, and substrate temperature ≤1000℃.

[0030] To operate CatCVD equipment, it is necessary to set the process parameters: power, catalytic hot wire temperature, gas flow rate; select the appropriate B / C, reaction chamber pressure, deposition time, etc. The thickness of the surface catalytic layer is mainly controlled by the deposition time. The purity of the surface catalytic layer is mainly controlled by controlling the gas ratio and the pressure in the reaction chamber. Compared with traditional CVD equipment (such as DCPJCVD equipment, MPCVD equipment, etc.), CatCVD equipment has the following advantages: lower substrate temperature (as low as 300°C) protects the Magnèli phase low-valent titanium oxide in the intermediate transition layer, providing a guarantee for the production of Ti / Magnèli / BDD environmental catalytic electrodes; large-area thin film deposition is achieved, making it easier to realize the engineering application of electrodes; gas source molecules can be decomposed at any gas pressure, so that the deposition of thin films has greater freedom; gas source utilization is higher, and the cost of producing electrodes is lower. The purpose of using Ti / Magnèli electrodes as substrate electrodes: BDD can be smoothly crystallized and formed into films on the surface of this substrate electrode; using Ti as the electrode substrate is cheaper than Nb and easier to obtain large-sized electrodes than wafers.

[0031] The prepared Ti / Magnèli electrode is used as a base electrode, and a BDD surface catalytic layer is obtained by processing with a CatCVD device. The thickness of the surface catalytic layer is ≥1 nm, thereby obtaining a Ti / Magnèli / BDD environmental catalytic electrode.

[0032] A Ti / Magnèli / BDD environmental catalytic electrode of this embodiment is prepared according to the preparation method.

[0033] A sewage treatment method of this embodiment uses the Ti / Magnèli / BDD environmental catalytic electrode as an electrode to perform electrochemical treatment of sewage.

[0034] The preparation method of the Ti / Magnèli / BDD environmental catalytic electrode, in the preparation step of the Magnèli phase low-valent titanium oxide intermediate transition layer, the working gas (reducing or inert protective gas) is preferably: the main gas is argon or nitrogen, and the secondary gas is hydrogen or helium.

[0035] A method for preparing a Ti / Magnèli / BDD environmental catalytic electrode. In the step of preparing a Magnèli phase low-valent titanium oxide intermediate transition layer, the range of the adjusted working gas is: main gas pressure and flow rate: 0.4-0.65 MPa and 1.2-3 m³ / h, secondary gas pressure and flow rate: 0.25-0.4 MPa and 0-1.2 m³ / h.

[0036] The preparation method of Ti / Magnèli / BDD environmental catalytic electrode, in the preparation step of the Magnèli phase low-valent titanium oxide intermediate transition layer, the Magnèli phase low-valent titanium oxide powder is a compound with the chemical formula TinO2n-1 or a mixture with the compound as the main component.

[0037] A method for preparing a Ti / Magnèli / BDD environmental catalytic electrode, wherein in the step of preparing a Magnèli phase low-valent titanium oxide intermediate transition layer, the Magnèli phase low-valent titanium oxide powder is Ti4O7 or a mixture of Ti4O7 and Ti5O9. The method for preparing a Ti / Magnèli / BDD environmental catalytic electrode of the present invention, wherein in the step of preparing a Magnèli phase low-valent titanium oxide intermediate transition layer, Magnèli phase low-valent titanium oxide powder is plasma sprayed by atmospheric plasma spraying equipment to prepare a Magnèli phase low-valent titanium oxide intermediate transition layer, the intermediate transition layer has a thickness of 1 to 10000 μm, and a coating porosity of 1 to 50%, thereby preparing a Ti / Magnèli electrode.

[0038] The preparation method of the Ti / Magnèli / BDD environmental catalytic electrode, in the CatCVD (hot wire chemical vapor deposition) step, the reaction gas is: CH4; H2; B(OCH3)3, B2H6 or other boron compound gas.

[0039] The preparation method of Ti / Magnèli / BDD environmental catalytic electrode, in which the parameters of the CatCVD (hot wire chemical vapor deposition method) equipment are: gas ratio CH4 (flow rate 1.0~10.0sccm), H2 (flow rate 200.0sccm), B(OCH3)3 (flow rate 1.0~15.0sccm); catalytic hot wire material W or Ta; catalytic hot wire temperature is 200~2000℃, and substrate temperature is ≤1000℃.

[0040] A method for preparing a Ti / Magnèli / BDD environmental catalytic electrode, using the prepared Ti / Magnèli electrode as a base electrode, preparing a BDD (boron-doped diamond film) surface catalytic layer by CatCVD (hot wire chemical vapor deposition) equipment, wherein the thickness of the surface catalytic layer is ≥10nm, to obtain a Ti / Magnèli / BDD environmental catalytic electrode.

[0041] The present invention also provides a Ti / Magnèli / BDD environmental catalytic electrode, which is prepared according to the above preparation method.

[0042] The Ti / Magnèli / BDD environmental catalytic electrode of the present invention is used as an electrode for electrochemical treatment of sewage. Experimental studies have shown that when the current density is 20mA / cm², the pH value is 7.0, and the reaction time is 120 min, the treatment effect of the Ti / Magnèli / BDD environmental catalytic electrode is excellent, and the removal rate of COD in printing and dyeing sewage can reach more than 90%.

[0043] The material of the anode electrode is the core of the electrochemical oxidation technology. Commonly used electrode materials mainly include: graphite electrode, titanium-based precious metal oxide electrode (DSA), lead and titanium-based lead dioxide electrode, titanium-based tin dioxide electrode, tin-antimony electrode and other categories. They all have their own characteristics in electrochemical wastewater treatment, but there are also some defects. Graphite electrode: low peroxygen potential, poor catalytic ability, easy to powder and peel off during use, short life; DSA (titanium-based precious metal oxide electrode) electrode: long life, but the overpotential is not high enough, and the power consumption is mostly used for the catalytic decomposition of organic matter in water, rather than the degradation of organic matter; lead and titanium-based lead dioxide electrode, titanium-based tin dioxide electrode and tin-antimony electrode: strong ability to degrade organic matter, but easy to peel off, and will cause heavy metals to exceed the standard and form secondary pollution. The present invention can significantly overcome the defects of commonly used electrodes.

[0044] The intermediate transition layer of Magnèli phase low-valent titanium oxide prepared by plasma spraying Magnèli phase low-valent titanium oxide powder with atmospheric plasma spraying equipment has a stable rutile structure, and its thermal expansion coefficient is close to that of Ti. The interface bonding force between the intermediate transition layer and the Ti substrate is high, and a Ti / Magnèli electrode with good stability can be prepared. Since the intermediate transition layer of the Ti / Magnèli electrode has a roughened surface and a certain coating porosity, it is conducive to the formation of a BDD (boron-doped diamond film) surface catalytic layer. Therefore, on the basis of the Ti / Magnèli electrode, a BDD (boron-doped diamond film) surface catalytic layer with a special sp3 structure and a low thermal expansion coefficient is prepared by CatCVD (hot wire chemical vapor deposition) equipment, thereby obtaining a Ti / Magnèli / BDD environmental catalytic electrode. The electrode has a wide electrochemical window in aqueous solution, a high oxygen evolution potential, low background current, current efficiency and electrochemical activity are better than other electrodes, and the electrochemical performance is stable and corrosion resistance is strong.

[0045] For example, in 1 mol / L sulfuric acid medium, the potential of Ti / Magnèli / BDD is much higher than that of Pt electrode and graphite electrode (see Figure 4). The researchers found that in the electrochemical potential window in 0.5 mol / L sulfuric acid medium, the Ti / Magnèli / BDD environmental catalytic electrode is 3.5 V (vs. Ag / AgCl), the glassy carbon electrode is 2.8 V (vs. Ag / AgCl), the Pt electrode is 1.7 V (vs. Ag / AgCl), and the Au electrode is 2.0 V (vs. Ag / AgCl). In general, the Ti / Magnèli / BDD environmental catalytic electrode has reached the decomposition potential of most organic matter before reaching its oxygen evolution potential, and has less oxygen evolution side reactions and high current efficiency in treating organic matter.

[0046] 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 present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

[0047] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for preparing a Ti / Magnèli / BDD environmental catalytic electrode for sewage treatment, characterized in that: The following steps are involved: yes A sandwich structure electrode, with Ti as the electrode matrix, Magnèli phase low-valent titanium oxide as the intermediate transition layer, and BDD as the surface catalyst layer; The method comprises the following steps: Ti substrate pretreatment step, Magnèli phase low-valent titanium oxide intermediate transition layer preparation step and Ti / Magnèli / BDD environmental catalytic electrode preparation step; The Ti substrate is pretreated by sandblasting with 10-900 mesh corundum and steaming with 1-90% concentration of oxalic acid; The step of preparing the Magnèli phase low-valent titanium oxide intermediate transition layer is to adjust the working gas and use an atmospheric plasma spraying device to prepare the Magnèli phase low-valent titanium oxide intermediate transition layer by plasma spraying the Magnèli phase low-valent titanium oxide powder to obtain a Ti / Magnèli electrode; The step of preparing the Ti / Magnèli / BDD environmental catalytic electrode is to use the prepared Ti / Magnèli electrode as a base electrode and obtain a BDD surface catalytic layer by processing with a CatCVD device.

2. The method for preparing a Ti / Magnèli / BDD environmental catalytic electrode for sewage treatment according to claim 1, characterized in that: Said In the step of preparing the Magnèli phase low-valent titanium oxide intermediate transition layer, the main working gas is argon or nitrogen, and the secondary working gas is hydrogen or helium.

3. The method for preparing a Ti / Magnèli / BDD environmental catalytic electrode for sewage treatment according to claim 2, characterized in that: Said In the preparation step of the Magnèli phase low-valent titanium oxide intermediate transition layer, the atmospheric plasma spraying equipment adjusts the working gas range: main gas pressure and flow rate: argon 0.4-0.65 MPa and nitrogen 1.2-3 m³ / h, secondary gas pressure and flow rate: hydrogen 0.25-0.4 MPa and helium 0-1.2 m³ / h.

4. The method for preparing a Ti / Magnèli / BDD environmental catalytic electrode for sewage treatment according to claim 1, characterized in that: In the step of preparing the Magnèli phase low-valent titanium oxide intermediate transition layer, the Magnèli phase low-valent titanium oxide powder is a compound with a chemical formula of TinO2n-1.

5. The method for preparing a Ti / Magnèli / BDD environmental catalytic electrode for sewage treatment according to claim 4, characterized in that: In the step of preparing the Magnèli phase low-valent titanium oxide intermediate transition layer, the Magnèli phase low-valent titanium oxide powder is Ti4O7 or a mixture of Ti4O7 and Ti5O9 with a content of ≥10% and a particle size of 1 to 1600 μm.

6. The method for preparing a Ti / Magnèli / BDD environmental catalytic electrode for sewage treatment according to claim 1, characterized in that: In the step of preparing the Magnèli phase low-valent titanium oxide intermediate transition layer, the Magnèli phase low-valent titanium oxide powder is plasma sprayed by atmospheric plasma spraying equipment to prepare the Magnèli phase low-valent titanium oxide intermediate transition layer, the thickness of the intermediate transition layer is 1 to 10000 μm, and the coating porosity is 1 to 50%, thereby obtaining a Ti / Magnèli electrode; Magnèli phase low-valent titanium oxide is easily oxidized in high temperature ≥600℃ atmospheric environment. In order to avoid excessive oxidation and ensure that the content of Ti4O7 or the mixture of Ti4O7 and Ti5O9 in the intermediate transition layer meets the standard, the flow rate of the reducing working gas or the inert protective gas should be controlled; the thickness of the intermediate transition layer is controlled by the movement speed of the spray gun; the porosity of the coating is controlled by controlling the hydrogen flow rate. The hydrogen flow rate is 1L / min, the porosity is 8.23%; the hydrogen flow rate is 8L / min, the porosity is 2.55%.

7. The method for preparing a Ti / Magnèli / BDD environmental catalytic electrode for sewage treatment according to claim 1, characterized in that: In the CatCVD hot wire chemical vapor deposition method, the reaction gas is: CH4; H2; B(OCH3)3, B2H6 or boron compound gas.

8. The method for preparing a Ti / Magnèli / BDD environmental catalytic electrode for sewage treatment according to claim 1, characterized in that: In the CatCVD step, the parameters of the CatCVD equipment are: gas ratio CH4 flow rate 1.0-50.0 sccm, H2 flow rate 200.0 sccm, B(OCH3)3 flow rate 1.0-50.0 sccm; catalytic hot wire material W or Ta, catalytic hot wire temperature 200-2000°C, substrate temperature ≤1000°C; The prepared Ti / Magnèli electrode is used as a base electrode, and a BDD surface catalytic layer is obtained by processing with a CatCVD device. The thickness of the surface catalytic layer is ≥1 nm, thereby obtaining a Ti / Magnèli / BDD environmental catalytic electrode.

9. A Ti / Magnèli / BDD environmental catalytic electrode, characterized in that: It is prepared according to the preparation method described in any one of claims 1 to 8.

10. A method for treating sewage, characterized in that: The Ti / Magnèli / BDD environmental catalytic electrode described in claim 9 is used as an electrode for electrochemical treatment of sewage.

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