A tantalum-based boron-doped diamond semiconductor composite coating material, a preparation method and application thereof

Abstract

This invention discloses a tantalum-based boron-doped diamond semiconductor composite coating material, its preparation method, and its applications. The tantalum-based boron-doped diamond semiconductor composite coating material comprises a tantalum substrate, a Ta-B compound gradient transition layer disposed on the surface of the tantalum substrate, and a gradient boron-doped diamond semiconductor layer disposed on the surface of the Ta-B compound gradient transition layer. The boron content in the Ta-B compound gradient transition layer increases from bottom to top; the boron content in the gradient boron-doped diamond semiconductor layer decreases from bottom to top; and the gradient boron-doped diamond semiconductor layer also contains Ta dopant. The composite coating material provided by this invention exhibits good film-substrate bonding performance, excellent conductivity, high stability, and good electrochemical performance.

Description

Technical Field

[0001] This invention relates to a tantalum-based boron-doped diamond semiconductor composite coating material, its preparation method, and its application, belonging to the field of materials preparation. Background Technology

[0002] Diamond possesses excellent physicochemical properties. Its hardness, molar density, thermal conductivity, sound velocity, and elastic modulus are the highest among known materials. It also exhibits good corrosion resistance, light transmittance, heat resistance, and radiation resistance. Pure diamond has a very high resistivity, making it an excellent electrical insulator. Doping diamond with boron atoms transforms it from an insulator with a bandgap of 5.47 eV into a semiconductor or even a conductor, greatly expanding its application range. At low doping levels, diamond exhibits semiconductor properties, with high electron / hole mobility, making it an ideal material for fabricating high-temperature semiconductors and radiation-resistant semiconductors. At high doping levels, diamond exhibits semi-metallic conductivity, making it an ideal anolyte material for electrochemical synthesis, electrochemical oxidation, and electrochemical analysis. Using chemical vapor deposition (CVD) technology, boron-doped diamond (BDD) coatings can be deposited on various substrates within a reasonable timescale and controllable doping range.

[0003] Ta-based boron-doped diamond (BDD) materials possess extremely high oxygen evolution potential, good mechanical strength, and electrical conductivity, making them excellent anolyte materials in the field of electrochemistry. The stability of diamond on the substrate is directly affected by the high thermal stress on both the diamond and substrate surfaces. Due to the significant difference in thermal expansion coefficients between the diamond coating and the Ta substrate, cooling the system from the high reaction temperature to ambient temperature can cause substantial residual stress, leading to coating delamination. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the first objective of this invention is to provide a tantalum-based boron-doped diamond semiconductor composite coating material that possesses both high adhesion and high stability in a composite coating.

[0005] The second objective of this invention is to provide a method for preparing a tantalum-based boron-doped diamond semiconductor composite coating material.

[0006] The third objective of this invention is to provide an application of a tantalum-based boron-doped diamond semiconductor composite coating material.

[0007] To achieve the above objectives, the present invention adopts the following technical solution:

[0008] This invention discloses a tantalum-based boron-doped diamond semiconductor composite coating material, comprising a tantalum substrate, a Ta-B compound gradient transition layer disposed on the surface of the tantalum substrate, and a gradient boron-doped diamond semiconductor layer disposed on the surface of the Ta-B compound gradient transition layer. The boron content in the Ta-B compound gradient transition layer increases from bottom to top; the boron content in the gradient boron-doped diamond semiconductor layer decreases from bottom to top; and the gradient boron-doped diamond semiconductor layer further contains Ta dopant.

[0009] This invention prepares a B-Ta compound gradient transition layer with a linear gradient at the interface between the BDD coating and the Ta substrate, and does Ta element doping in the BDD coating. Without adding other elements, the chemical bonding force between the BDD coating and the Ta substrate is increased, the residual stress is reduced, and the film-substrate bonding performance and service stability of the Ta-based BDD semiconductor composite coating material are significantly improved.

[0010] The present invention discloses a tantalum-based boron-doped diamond semiconductor composite coating material, wherein the top of the Ta-B compound gradient transition layer is selected from at least one of the following: TaB / Ta3B4 multiphase, TaB / Ta3B4 / TaB2 multiphase, TaB / TaB2 multiphase, TaB single phase, Ta3B4 single phase, and TaB2 single phase.

[0011] In this invention, the boron content in the Ta-B compound gradient transition layer increases from bottom to top. The bottom layer has a lower B content and preferentially forms the TaB phase. TaB further combines with B to obtain Ta3B4, and Ta3B4 further combines with B to obtain TaB2.

[0012] In this invention, the introduction of a Ta-B compound gradient transition layer reduces the absorption of active C atoms by Ta, increasing the nucleation rate of diamond. Simultaneously, both TaB and TaB2 in the transition layer are highly conductive phases with thermal expansion coefficients between those of diamond and pure tantalum, creating a favorable transition between Ta and BDD. The bottom layer of the transition layer has a low boron content, which helps retain the mechanical properties and conductivity of the metal substrate; the top layer has a higher boron content to enhance the chemical bonding between the transition layer and the BDD coating (gradient boron-doped diamond semiconductor layer), further improving the film-substrate bonding performance; the intermediate layer uses a gradient increase in boron content, causing a slow change in the thermal expansion coefficient of the substrate, preventing residual stress concentration at the interface and delamination, further improving the film-substrate bonding.

[0013] This invention discloses a tantalum-based boron-doped diamond semiconductor composite coating material, wherein the thickness of the Ta-B compound gradient transition layer is 5-100 μm. The inventors discovered that controlling the thickness of the transition layer within this range yields optimal performance. If the transition layer is too thin, the boron content in the transition layer is low, which fails to effectively improve the chemical bonding with the gradient boron-doped diamond coating and alleviate residual stress; if the transition layer is too thick, the bond between the transition layer and the substrate is weak, resulting in brittleness and easy peeling.

[0014] This invention discloses a tantalum-based boron-doped diamond semiconductor composite coating material. The gradient boron-doped diamond semiconductor layer comprises, from bottom to top, a boron-doped diamond bottom layer, a boron-doped diamond intermediate layer, and a boron-doped diamond top layer. The boron-doped diamond bottom layer has a uniform boron content, with a B / C ratio of 46,666-60,000 ppm on an atomic ratio basis. The boron content in the boron-doped diamond intermediate layer decreases linearly from bottom to top, with the boron content in the boron-doped diamond bottom layer being the maximum value and decreasing linearly to the boron content in the boron-doped diamond top layer.

[0015] In this invention, the boron-doped diamond bottom layer uses a uniform boron content to increase the nucleation density of diamond while maximizing the conductivity of the substrate, enhancing the chemical bonding force between the BDD coating and the Ta-B compound gradient transition layer, and further improving the film-substrate bonding performance. The boron-doped diamond top layer also uses a uniform boron content to maximize the corrosion resistance of the top layer, effectively reduce the coating peeling rate, and improve the service life of the material. The boron-doped diamond intermediate layer adopts a linearly decreasing boron gradient, which allows for a natural transition between coatings, making it less prone to separation and breakage, and improving the bonding force.

[0016] This invention discloses a tantalum-based boron-doped diamond semiconductor composite coating material, wherein the gradient boron-doped diamond semiconductor layer is uniformly deposited on the surface of a Ta-B compound gradient transition layer by chemical vapor deposition, and the thickness of the gradient boron-doped diamond semiconductor layer is 1μm-2mm.

[0017] Specifically, a boron-doped diamond bottom layer, a boron-doped diamond intermediate layer, and a boron-doped diamond top layer are first deposited on the surface of the Ta-B compound gradient transition layer, and finally a boron-doped diamond top layer is deposited.

[0018] In this invention, the boron-doped diamond bottom layer, the boron-doped diamond middle layer, and the boron-doped diamond top layer all have the same thickness range.

[0019] This invention discloses a tantalum-based boron-doped diamond semiconductor composite coating material. The boron-doped diamond semiconductor layer contains TaC or Ta₂C, and the atomic percentage of tantalum in the boron-doped diamond semiconductor layer is 2%-15%. In this invention, adding Ta to the gradient boron-doped diamond semiconductor layer is beneficial to improving diamond grain growth. Within the scope of this invention, the higher the atomic percentage of Ta, the larger the diamond grain size and the more secondary nucleation in the resulting BDD coating. Simultaneously, Ta possesses excellent properties such as high ductility, high chemical activity, and low resistivity. Doping Ta into the BDD coating helps reduce the coating resistivity without reducing mechanical properties. Furthermore, Ta doping in the BDD coating can further enhance the chemical bonding force between the BDD coating and the Ta substrate, improving the film-substrate bonding performance.

[0020] In this invention, the composite coating material with a Ta atomic percentage of 2%-15% exhibits the best performance. Because Ta atoms are relatively large, excessively high doping concentrations can lead to extensive secondary nucleation and twinning, and may even cause significant lattice distortion, reducing the original electrocatalytic oxidation performance of the BDD coating; conversely, excessively low doping concentrations result in insignificant doping effects.

[0021] This invention relates to a tantalum-based boron-doped diamond semiconductor composite coating material, wherein the tantalum in the tantalum matrix is ​​selected from pure Ta or Ta alloys.

[0022] This invention relates to a tantalum-based boron-doped diamond semiconductor composite coating material, wherein the tantalum substrate has a structure of zero-dimensional, one-dimensional, two-dimensional, or three-dimensional.

[0023] This invention discloses a tantalum-based boron-doped diamond semiconductor composite coating material, wherein the tantalum substrate surface has a micro-nano structure.

[0024] In this invention, the fabrication method of the micro-nano structure is not limited, such as at least one of high-temperature atmosphere etching, high-temperature metal etching, and plasma etching.

[0025] This invention discloses a method for preparing a tantalum-based boron-doped diamond semiconductor composite coating material. The method involves boron doping on the surface of a tantalum substrate to obtain a Ta-B compound gradient transition layer. The tantalum substrate containing the Ta-B compound gradient transition layer is then placed in a hot-wire chemical vapor deposition furnace. A tantalum wire is placed in front of the hot wire, and boron-containing gas is introduced. A gradient boron-doped diamond semiconductor layer is grown through chemical vapor deposition, thus obtaining the tantalum-based boron-doped diamond semiconductor composite coating material.

[0026] In practical operation, pure Ta or Ta alloys of different sizes and alloy element contents are used as substrate materials. After cleaning and degreasing, a porous structure can be formed on the surface by acid etching, which further improves the adhesion between the film and the substrate in subsequent film formation. For example, the Ta substrate is placed in a mixed solution of 10% HF + 10% HNO3 + 80% H2O and ultrasonically etched for 60 seconds.

[0027] This invention discloses a method for preparing a tantalum-based boron-doped diamond semiconductor composite coating material, which involves using magnetron sputtering or high-temperature heat treatment to perform boron doping on the surface of a tantalum substrate to obtain a Ta-B compound gradient transition layer.

[0028] The inventors discovered that when using a high-temperature heat treatment method, since the penetration of boron is from the surface to the interior, a gradient transition layer of boron-doped Ta-B compound can be formed, in which the boron content increases from bottom to top. When using a magnetron sputtering method, the boron content in the Ta-B compound gradient transition layer can be adjusted by the sputtering power and the proportion of boron-containing atmosphere.

[0029] In a further preferred embodiment, the magnetron sputtering process is as follows: multi-target magnetron sputtering is performed on the Ta substrate using Ta and B targets with a purity ≥99.99%; the sputtering parameters of the multi-target magnetron sputtering are: sputtering power of Ta target is 30-90W, sputtering power of B target is 100-300W, working gas pressure is 0.2-3Pa, distance between substrate and target is 5-12cm, and sputtering time is 90-180min;

[0030] Alternatively, the Ta substrate can be placed in a B-containing atmosphere for DC magnetron sputtering; during DC magnetron sputtering, a Ta target or TaB target with a purity ≥99.99% is used, the distance between the substrate and the target is 5-12 cm, the working pressure is 0.2-3 Pa, the sputtering power is 40-200 W, and the sputtering time is 5-100 min.

[0031] In a further preferred embodiment, after the magnetron sputtering process is completed, the tantalum substrate containing the Ta-B compound gradient transition layer is subjected to low-temperature heat treatment. The temperature of the low-temperature heat treatment is 500-1100℃, the time of the low-temperature heat treatment is 1-6h, the gas pressure is 8-25kPa, and the atmosphere of the low-temperature heat treatment is an inactive atmosphere.

[0032] More preferably, the inactive atmosphere is selected from at least one of hydrogen, argon, and helium.

[0033] The inventors discovered that after magnetron sputtering, the tantalum substrate containing a Ta-B compound gradient transition layer undergoes low-temperature heat treatment and surface etching, followed by deposition and growth of a gradient boron-doped diamond semiconductor layer, resulting in higher uniformity and better bonding performance.

[0034] In a preferred embodiment, the high-temperature heat treatment process is as follows: the Ta matrix is ​​placed in a B-rich atmosphere, infiltrated with B salt or solid B powder, and subjected to high-temperature heat treatment; the high-temperature heat treatment temperature is 1000-2000℃, the high-temperature heat treatment time is 1-20h, and the working pressure is 2-10kPa; the high-temperature heat treatment atmosphere is an inactive atmosphere, such as at least one of hydrogen, helium, and argon, preferably argon.

[0035] In a further preferred embodiment, the B source is selected from a gaseous boron source and a solid boron source. The gaseous boron source is selected from one of borane, boron chloride, and boron bromide, preferably diborane. The solid boron source is selected from one of B powder and B salt, preferably B powder.

[0036] In this invention, compared to other preparation methods, the reaction of elemental B directly with the matrix requires a lower temperature and results in a more complete reaction.

[0037] More preferably, the particle size of the solid B powder is ≤20μm.

[0038] The inventors discovered that by using a tantalum substrate coated with high-purity ultrafine boron powder with a particle size ≤20μm and controlling the heat treatment temperature within the aforementioned preferred range, the resulting transition layer has the best quality, and the performance of the obtained tantalum-based boron-doped diamond semiconductor composite coating material is also the best.

[0039] The Ta-B compound gradient transition layer prepared by magnetron sputtering can be surface etched by high-temperature heat treatment; the heat treatment atmosphere is an inactive gas, such as hydrogen, argon, helium, etc.; the heat treatment temperature is 500-1100℃, the heat treatment time is 1-6h, and the gas pressure is 8-25kPa.

[0040] In this invention, the preparation method of the Ta-B compound gradient transition layer is not limited to the above two methods. As long as the thickness and composition requirements of the transition layer can be met, one of the existing technologies such as electroplating, vapor deposition, magnetron sputtering, chemical vapor deposition, and physical vapor deposition can be used.

[0041] In a preferred embodiment, the process of growing a gradient boron-doped diamond semiconductor layer by chemical vapor deposition is as follows: a tantalum substrate containing a Ta-B compound gradient transition layer is placed in a chemical vapor deposition furnace, and hydrogen, boron-containing gas, and carbon-containing gas are introduced. First, the percentage of boron-containing gas in the total gas flow rate in the furnace is controlled to be 0.069%-0.0884% to obtain a boron-doped diamond bottom layer. Then, the boron doping concentration is reduced linearly until the percentage of boron-containing gas in the total gas flow rate in the furnace is 0.03968%-0.0593% to obtain a boron-doped diamond transition layer. Then, the percentage of boron-containing gas in the total gas flow rate in the furnace is controlled to be 0.03968%-0.0593% again to obtain a boron-doped diamond top layer; thus, a gradient boron-doped diamond semiconductor layer is obtained.

[0042] The percentage of carbon-containing gas in the total gas mass flow rate in the furnace is 0.5-10.0%, preferably 2-5%; the boron-doped diamond deposition temperature is 600-1000℃, and the gas pressure is 10. 3 -10 4 Pa, deposition time is 3-20h.

[0043] A tantalum wire is placed in front of the hot wire in the chemical vapor deposition furnace; the tantalum wire has a purity of ≥99.95%, a diameter of 0.15-0.6 mm, and a length of 10-100 mm. The in-situ evaporation of the tantalum wire is achieved by absorbing heat from the hot wire during the diamond deposition process.

[0044] The preparation method of this invention involves growing a gradient boron-doped diamond semiconductor layer in a hot-wire chemical vapor deposition furnace. A tantalum wire is placed in front of the hot wire, and in-situ deposition of carbon and thermal evaporation of tantalum lead to the formation of TaC and Ta2C. The larger the diameter and the longer the length of the tantalum wire, the higher the percentage of Ta atoms.

[0045] The inventors discovered that when the length and diameter of the Ta filament are controlled within the range of this invention, the performance of the resulting composite coating material is optimal. If the diameter of the hot filament is too thin or the length is too short, the hot filament may melt during the CVD deposition process; if the diameter of the hot filament is too large or the length is too long, it will lead to excessive doping of Ta in diamond, affecting the electrocatalytic oxidation performance of the BDD coating.

[0046] In actual operation, seed crystals are first planted on the surface of a tantalum substrate containing a Ta-B compound gradient transition layer, and then a gradient boron-doped diamond semiconductor layer is grown in a chemical vapor deposition furnace. The seed crystal planting process is as follows: the Ta substrate with a Ta-B compound gradient transition layer on its surface is placed in a suspension containing a mixture of nanocrystalline and / or microcrystalline diamond particles; ultrasonic treatment is performed, and then it is dried; a substrate material with nanocrystalline and / or microcrystalline diamond adsorbed on its surface is obtained.

[0047] In the suspension containing nanocrystalline and / or microcrystalline diamond mixed particles, the mass fraction of diamond mixed particles is 0.01%-0.05%; the particle size of the diamond mixed particles is 5-30 nm, and the purity is ≥97%; the ultrasonic treatment time is 5-30 min.

[0048] The present invention also provides an application of tantalum-based boron-doped diamond semiconductor composite material, wherein the semiconductor composite coating material is applied to at least one of semiconductor devices, electrochemical oxidation, electrochemical synthesis, and electrochemical analysis.

[0049] Beneficial effects

[0050] This invention addresses the problem of low stability in Ta-based BDD composite coating materials caused by the mismatch in thermal expansion coefficients between Ta and BDD. By preparing a B-Ta compound gradient transition layer with a linear gradient at the interface between the BDD coating and the Ta substrate, and by doping the BDD coating with Ta, the chemical bonding force between the BDD coating and the Ta substrate is increased and the residual stress is reduced without adding other elements. This significantly improves the film-substrate bonding performance and service stability of the Ta-based BDD semiconductor composite coating material. Attached Figure Description

[0051] Figure 1 The graph shows the change in borane concentration when preparing the Ta-B compound gradient transition layer by magnetron sputtering in Example 3. Detailed Implementation

[0052] Example 1

[0053] Pure Ta matrix was encapsulated in solid boron powder with a particle size of 5 μm. The mixture was placed in a tube furnace and heat-treated with argon gas as a protective gas at a pressure of 3 kPa and a heating temperature of 1200 °C. After holding at this temperature for 5 hours, the furnace was cooled. The resulting Ta-B compound gradient transition layer had a top composition of TaB / Ta3B4 / TaB2 multiphase, with a transition layer thickness of 7.3 μm.

[0054] Then, a Ta substrate with a Ta-B compound gradient transition layer on its surface is placed in a suspension containing a mixture of nanocrystalline and / or microcrystalline diamond particles; ultrasonic treatment is performed, followed by drying; a substrate material with surface-adsorbed nanocrystalline and / or microcrystalline diamond is obtained; the mass fraction of the diamond mixture particles in the suspension containing nanocrystalline and / or microcrystalline diamond particles is 0.03%; the particle size of the diamond mixture particles is 5-10 nm, and the purity is ≥97%; the ultrasonic treatment time is 30 min.

[0055] A substrate material with surface-adsorbed nanocrystalline and / or microcrystalline diamond is placed in a chemical vapor deposition furnace, and hydrogen, boron-containing gas, and carbon-containing gas are introduced. First, the percentage of boron-containing gas in the total gas flow rate in the furnace is controlled to be 0.0884% to obtain a boron-doped diamond bottom layer. Then, the boron doping concentration is reduced in a linear decreasing manner until the percentage of boron-containing gas in the total gas flow rate in the furnace is 0.0593% to obtain a boron-doped diamond intermediate layer. Then, the percentage of boron-containing gas in the total gas flow rate in the furnace is controlled to be 0.03968% to obtain a boron-doped diamond top layer. Thus, a gradient boron-doped diamond semiconductor layer is obtained.

[0056] The carbon-containing gas accounts for 2.5% of the total gas mass flow rate in the furnace, the boron-doped diamond deposition temperature is 800℃, and the gas pressure is 10. 3 Pa, deposition time was 15h.

[0057] A Ta wire is placed in front of the hot filament in the hot filament chemical vapor deposition furnace; the purity of the Ta wire is ≥99.95%, the diameter of the Ta wire is 0.5 mm, and the length is 25 mm.

[0058] The prepared gradient boron-doped diamond semiconductor layer has a thickness of 13.2 μm, an average diamond grain size of 1.30 μm, and an atomic percentage of Ta in the coating of 5.32%.

[0059] Using the coating material as the anode and a Ti plate of the same specifications as the cathode, the current density was controlled at 60 mA / cm². 2 A degradation experiment was conducted using simulated dye wastewater (500 mL of 0.1 g / L RB-19 solution, 0.5 M sodium sulfate) as the research object. After 4 hours of degradation, the wastewater changed from deep blue to colorless and clear, with a color removal rate of 99% and an energy consumption of 1.03 kWh / m³ for color removal. 3 ·A -1 .

[0060] Using the coated electrode as the anode and a Ti plate of the same specifications as the cathode, the current density was controlled at 1 A / cm². 2 An accelerated service life test was conducted in a 1 mol / L H₂SO₄ solution. After 600 hours of electrolysis, the cell voltage rapidly increased, and the electrode completely failed. The accelerated service life of this electrode, converted to an actual service life of 240,000 hours, demonstrates long stability and lifespan, making it suitable for industrial applications.

[0061] Example 2

[0062] A pure Ta matrix was encapsulated in a solid infiltrator and heat-treated in a tube furnace under argon gas as a protective gas. The solid infiltrator consisted of 5 wt% B4C + 5 wt% KBF4 + 90 wt% SiC. The gas pressure was set to 3 kPa, the heating temperature was 1400℃, and the furnace was cooled after holding at this temperature for 4 hours. The resulting Ta-B compound gradient transition layer had a top composition of TaB / Ta3B4 multiphase and a thickness of 6.9 μm.

[0063] Then, a Ta substrate with a Ta-B compound gradient transition layer on its surface is placed in a suspension containing a mixture of nanocrystalline and / or microcrystalline diamond particles; ultrasonic treatment is performed, followed by drying; a substrate material with surface-adsorbed nanocrystalline and / or microcrystalline diamond is obtained; the mass fraction of the diamond mixture particles in the suspension containing nanocrystalline and / or microcrystalline diamond particles is 0.03%; the particle size of the diamond mixture particles is 5-10 nm, and the purity is ≥97%; the ultrasonic treatment time is 30 min.

[0064] A substrate material with surface-adsorbed nanocrystalline and / or microcrystalline diamond is placed in a chemical vapor deposition furnace, and hydrogen, boron-containing gas, and carbon-containing gas are introduced. First, the percentage of boron-containing gas in the total gas flow rate in the furnace is controlled to be 0.0884% to obtain a boron-doped diamond bottom layer. Then, the boron doping concentration is reduced in a linear decreasing manner until the percentage of boron-containing gas in the total gas flow rate in the furnace is 0.0593% to obtain a boron-doped diamond intermediate layer. Then, the percentage of boron-containing gas in the total gas flow rate in the furnace is controlled to be 0.03968% to obtain a boron-doped diamond top layer. Thus, a gradient boron-doped diamond semiconductor layer is obtained.

[0065] The carbon-containing gas accounts for 3% of the total gas mass flow rate in the furnace, the boron-doped diamond deposition temperature is 800℃, and the gas pressure is 10. 3 Pa, deposition time was 15h.

[0066] A Ta wire is placed in front of the hot filament in the hot filament chemical vapor deposition furnace; the purity of the Ta wire is ≥99.95%, the diameter of the Ta wire is 0.5 mm, and the length is 70 mm.

[0067] The prepared gradient boron-doped diamond semiconductor layer has a thickness of 12.5 μm, an average diamond grain size of 1.80 μm, and an atomic percentage of Ta in the coating of 7.32%.

[0068] Using the coating material as the anode and a Ti plate of the same specifications as the cathode, the current density was controlled at 60 mA / cm². 2A degradation experiment was conducted using simulated dye wastewater (500 mL of 0.1 g / L RB-19 solution, 0.5 M sodium sulfate) as the research object. After 4 hours of degradation, the wastewater changed from deep blue to colorless and clear, with a color removal rate of 99% and an energy consumption of 0.88 kWh / m³ for color removal. 3 ·A -1 .

[0069] Using the coated electrode as the anode and a Ti plate of the same specifications as the cathode, the current density was controlled at 1 A / cm². 2 An accelerated service life test was conducted in a 1 mol / L H₂SO₄ solution. After 550 hours of electrolysis, the cell voltage rapidly increased, and the electrode completely failed. The accelerated service life of this electrode, converted to an actual service life of 220,000 hours, demonstrates long stability and lifespan, making it suitable for industrial applications.

[0070] Example 3

[0071] The Ta substrate was placed in a B-containing atmosphere for DC magnetron sputtering. During magnetron sputtering, a Ta target with a purity ≥99.99% was used, the substrate-target distance was 5 cm, the working pressure was 0.2 Pa, the sputtering power was 90 W, and the sputtering time was 60 min. The sputtering atmosphere was a mixture of diborane and argon, with an initial borane concentration of 5%, which was increased by 10% every 10 min until the borane concentration reached 30% (see...). Figure 1 The top of the gradient transition layer of the prepared Ta-B compound was composed of a TaB / TaB2 complex phase, and the thickness of the transition layer was 9.4 μm.

[0072] After the magnetron sputtering is completed, the tantalum substrate containing the Ta-B compound gradient transition layer is subjected to low-temperature heat treatment. The temperature of the low-temperature heat treatment is 600℃, the time of the low-temperature heat treatment is 2h, the gas pressure is 10kPa, and the atmosphere of the low-temperature heat treatment is argon.

[0073] Then, a Ta substrate with a Ta-B compound gradient transition layer on its surface is placed in a suspension containing a mixture of nanocrystalline and / or microcrystalline diamond particles; ultrasonic treatment is performed, followed by drying; a substrate material with surface-adsorbed nanocrystalline and / or microcrystalline diamond is obtained; the mass fraction of the diamond mixture particles in the suspension containing nanocrystalline and / or microcrystalline diamond particles is 0.03%; the particle size of the diamond mixture particles is 5-10 nm, and the purity is ≥97%; the ultrasonic treatment time is 30 min.

[0074] A substrate material with surface-adsorbed nanocrystalline and / or microcrystalline diamond is placed in a chemical vapor deposition furnace, and hydrogen, boron-containing gas, and carbon-containing gas are introduced. First, the percentage of boron-containing gas in the total gas flow rate in the furnace is controlled to be 0.0884% to obtain a boron-doped diamond bottom layer. Then, the boron doping concentration is reduced in a linear decreasing manner until the percentage of boron-containing gas in the total gas flow rate in the furnace is 0.0593% to obtain a boron-doped diamond intermediate layer. Then, the percentage of boron-containing gas in the total gas flow rate in the furnace is controlled to be 0.03968% to obtain a boron-doped diamond top layer; thus, a gradient boron-doped diamond semiconductor layer is obtained.

[0075] The carbon-containing gas accounts for 2.5% of the total gas mass flow rate in the furnace, the boron-doped diamond deposition temperature is 800℃, and the gas pressure is 10. 3 Pa, deposition time was 15h.

[0076] A Ta wire is placed in front of the hot filament in the hot filament chemical vapor deposition furnace; the purity of the Ta wire is ≥99.95%, the diameter of the Ta wire is 0.5 mm, and the length is 50 mm.

[0077] The prepared gradient boron-doped diamond semiconductor layer has a thickness of 16.3 μm, an average diamond grain size of 1.40 μm, and an atomic percentage of Ta in the coating of 6.04%.

[0078] Using the coating material as the anode and a Ti plate of the same specifications as the cathode, the current density was controlled at 60 mA / cm². 2 A degradation experiment was conducted using simulated dye wastewater (500 mL of 0.1 g / L RB-19 solution, 0.5 M sodium sulfate) as the research object. After 4 hours of degradation, the wastewater changed from deep blue to colorless and clear, with a color removal rate of 99% and an energy consumption of 0.96 kWh / m³ for color removal. 3 ·A -1 .

[0079] Using the coated electrode as the anode and a Ti plate of the same specifications as the cathode, the current density was controlled at 1 A / cm². 2 An accelerated service life test was conducted in a 1 mol / L H₂SO₄ solution. After 570 hours of electrolysis, the cell voltage rapidly increased, and the electrode completely failed. The accelerated service life of this electrode, converted to an actual service life of 230,000 hours, demonstrates long stability and lifespan, making it suitable for industrial applications.

[0080] Comparative Example 1

[0081] The conditions were the same as in Example 1, except that Ta doping was not performed when preparing the boron-doped diamond semiconductor layer. The thickness of the resulting gradient boron-doped diamond semiconductor layer was 11.7 μm, and the average diamond grain size was 1.10 μm.

[0082] Using the coating material as the anode and a Ti plate of the same specifications as the cathode, the current density was controlled at 60 mA / cm². 2 A degradation experiment was conducted using simulated dye wastewater (500 mL of 0.1 g / L RB-19 solution, 0.5 M sodium sulfate) as the research object. After 4 hours of degradation, the wastewater changed from deep blue to colorless and clear, with a color removal rate of 99% and an energy consumption of 2.14 kWh / m³ for color removal. 3 ·A -1 .

[0083] Using the coated electrode as the anode and a Ti plate of the same specifications as the cathode, the current density was controlled at 1 A / cm². 2 An accelerated service life test was conducted in a 1 mol / L H₂SO₄ solution. After 480 hours of electrolysis, the cell voltage rapidly increased, and the electrode completely failed. The accelerated service life of this electrode, converted to an actual service life of 200,000 hours, is far less than that of Example 1.

[0084] Comparative Example 2

[0085] All other conditions were the same as in Example 1, except that the Ta-B compound gradient transition layer was not prepared on the substrate.

[0086] Using the coating material as the anode and a Ti plate of the same specifications as the cathode, the current density was controlled at 60 mA / cm². 2 A degradation experiment was conducted using simulated dye wastewater (500 mL of 0.1 g / L RB-19 solution, 0.5 M sodium sulfate) as the research object. After 4 hours of degradation, the wastewater changed from deep blue to colorless and clear, with a color removal rate of 99% and an energy consumption of 1.15 kWh / m³ for color removal. 3 ·A -1 .

[0087] Using the coated electrode as the anode and a Ti plate of the same specifications as the cathode, the current density was controlled at 1 A / cm². 2 An accelerated service life test was conducted in a 1 mol / L H₂SO₄ solution. After 400 hours of electrolysis, the cell voltage rapidly increased, and the electrode completely failed. The accelerated service life of this electrode, converted to an actual service life, was 160,000 hours, which is far less than that of Example 1.

[0088] Comparative Example 3

[0089] The conditions were the same as in Example 1, except that the length of the Ta wire used in the hot-wire chemical vapor deposition was 200 mm, the thickness of the resulting gradient boron-doped diamond semiconductor layer was 9.2 μm, the atomic percentage of Ta in the coating was 32.14%, and a large number of twins and pores were present on the coating surface.

[0090] Using the coating material as the anode and a Ti plate of the same specifications as the cathode, the current density was controlled at 60 mA / cm². 2 A degradation experiment was conducted using simulated dye wastewater (500 mL of 0.1 g / L RB-19 solution, 0.5 M sodium sulfate) as the research object. After 5 hours of degradation, the wastewater changed from deep blue to colorless and clear, with a color removal rate of 99% and an energy consumption of 0.96 kWh / m³ for color removal. 3 ·A -1 .

[0091] Using the coated electrode as the anode and a Ti plate of the same specifications as the cathode, the current density was controlled at 1 A / cm². 2 An accelerated service life test was conducted in a 1 mol / L H₂SO₄ solution. After 300 hours of electrolysis, the cell voltage rapidly increased, and the electrode completely failed. The accelerated service life of this electrode, converted to an actual service life of 120,000 hours, is far less than that of Example 1.

Claims

1. A tantalum-based boron-doped diamond semiconductor composite coating material, characterized in that: The tantalum-based boron-doped diamond semiconductor composite coating material comprises a tantalum substrate, a Ta-B compound gradient transition layer disposed on the surface of the tantalum substrate, and a gradient boron-doped diamond semiconductor layer disposed on the surface of the Ta-B compound gradient transition layer. The boron content in the Ta-B compound gradient transition layer increases from bottom to top, while the boron content in the gradient boron-doped diamond semiconductor layer decreases from bottom to top. The gradient boron-doped diamond semiconductor layer also contains Ta element doping.

2. The tantalum-based boron-doped diamond semiconductor composite coating material according to claim 1, characterized in that: The top of the Ta-B compound gradient transition layer is selected from at least one of the following: TaB / Ta3B4 multiphase, TaB / Ta3B4 / TaB2 multiphase, TaB / TaB2 multiphase, TaB single phase, Ta3B4 single phase, and TaB2 single phase. The thickness of the Ta-B compound gradient transition layer is 5-100 μm.

3. The tantalum-based boron-doped diamond semiconductor composite coating material according to claim 1, characterized in that: The gradient boron-doped diamond semiconductor layer, from bottom to top, includes a boron-doped diamond bottom layer, a boron-doped diamond intermediate layer, and a boron-doped diamond top layer. The boron-doped diamond bottom layer has a uniform boron content, with a B / C ratio of 46,666-60,000 ppm on an atomic ratio basis. The boron-doped diamond top layer has a uniform boron content, with a B / C ratio of 26,666-40,000 ppm on an atomic ratio basis. The boron content in the boron-doped diamond intermediate layer decreases linearly from bottom to top, with the boron content in the boron-doped diamond bottom layer being the maximum value and decreasing linearly to the boron content in the boron-doped diamond top layer. The gradient boron-doped diamond semiconductor layer is uniformly deposited on the surface of the Ta-B compound gradient transition layer by chemical vapor deposition, and the thickness of the gradient boron-doped diamond semiconductor layer is 1μm-2mm. The boron-doped diamond semiconductor layer contains TaC or Ta2C, and the atomic percentage of tantalum in the boron-doped diamond semiconductor layer is 2%-15%.

4. The tantalum-based boron-doped diamond semiconductor composite coating material according to claim 1, characterized in that: The tantalum in the tantalum matrix is ​​selected from pure Ta or Ta alloys; The structure of the tantalum matrix is ​​one of zero-dimensional, one-dimensional, two-dimensional, or three-dimensional. The tantalum substrate has a micro / nano structure on its surface.

5. A method for preparing a tantalum-based boron-doped diamond semiconductor composite coating material according to any one of claims 1-4, characterized in that: A Ta-B compound gradient transition layer is obtained by boron doping on the surface of a tantalum substrate. Then, the tantalum substrate containing the Ta-B compound gradient transition layer is placed in a hot-wire chemical vapor deposition furnace, a tantalum wire is placed in front of the hot wire, and boron-containing gas is introduced. A gradient boron-doped diamond semiconductor layer is grown by chemical vapor deposition, thus obtaining a tantalum-based boron-doped diamond semiconductor composite coating material.

6. The method for preparing a tantalum-based boron-doped diamond semiconductor composite coating material according to claim 5, characterized in that: A Ta-B compound gradient transition layer is obtained by boron doping on the surface of a tantalum substrate using magnetron sputtering or high-temperature heat treatment.

7. The method for preparing a tantalum-based boron-doped diamond semiconductor composite coating material according to claim 6, characterized in that: The magnetron sputtering process is as follows: Ta substrate was subjected to multi-target magnetron sputtering using Ta and B targets with a purity of ≥99.99%. The sputtering parameters for the multi-target magnetron sputtering were as follows: sputtering power of Ta target was 30~90W, sputtering power of B target was 100~300W, working gas pressure was 0.2-3Pa, spacing between substrate and target was 5~12cm, and sputtering time was 90~180min. or The Ta substrate is placed in a B-containing atmosphere for DC magnetron sputtering; during DC magnetron sputtering, a Ta target or TaB target with a purity ≥99.99% is used, the distance between the substrate and the target is 5-12cm, the working pressure is 0.2-3Pa, the sputtering power is 40~200W, and the sputtering time is 5-100min. After magnetron sputtering, the tantalum substrate containing the Ta-B compound gradient transition layer is subjected to low-temperature heat treatment. The temperature of the low-temperature heat treatment is 500-1100℃, the time is 1-6h, the pressure is 8-25kPa, and the atmosphere of the low-temperature heat treatment is an inactive atmosphere.

8. The method for preparing a tantalum-based boron-doped diamond semiconductor composite coating material according to claim 6, characterized in that: The high-temperature heat treatment process is as follows: the Ta matrix is ​​placed in a B-rich atmosphere, infiltrated with B salt or solid B powder for high-temperature heat treatment; the temperature of the high-temperature heat treatment is 1000-2000℃, the time of the high-temperature heat treatment is 1-20h, and the working pressure is 2-10kPa; the high-temperature heat treatment atmosphere is an inactive atmosphere.

9. The method for preparing a tantalum-based boron-doped diamond semiconductor composite coating material according to claim 5, characterized in that: The process of growing a gradient boron-doped diamond semiconductor layer by chemical vapor deposition is as follows: A tantalum substrate containing a Ta-B compound gradient transition layer is placed in a chemical vapor deposition furnace, and hydrogen, boron-containing gas, and carbon-containing gas are introduced. First, the percentage of boron-containing gas in the total gas flow rate in the furnace is controlled to be 0.069%-0.0884% to obtain a boron-doped diamond bottom layer. Then, the boron doping concentration is reduced linearly until the percentage of boron-containing gas in the total gas flow rate in the furnace is 0.03968%-0.0593% to obtain a boron-doped diamond transition layer. Then, the percentage of boron-containing gas in the total gas flow rate in the furnace is controlled to be 0.03968%-0.0593% again to obtain a boron-doped diamond top layer; thus, a gradient boron-doped diamond semiconductor layer is obtained. The percentage of carbon-containing gas in the total gas mass flow rate in the furnace is 0.5-10.0%, the boron-doped diamond deposition temperature is 600-1000℃, and the gas pressure is 10. 3 -10 4 Pa, deposition time 3-20h; A tantalum wire is placed in front of the hot wire in the chemical vapor deposition furnace; the tantalum wire has a purity of ≥99.95%, a diameter of 0.15~0.6mm, and a length of 10~100mm.

10. The application of the tantalum-based boron-doped diamond semiconductor composite coating material according to any one of claims 1-4, characterized in that: The tantalum-based boron-doped diamond semiconductor composite coating material is applied to one of the following: semiconductor devices, electrochemical oxidation, electrochemical synthesis, and electrochemical analysis.

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