Diamond electrode and preparation method thereof

Abstract

The invention discloses a diamond electrode and a preparation method thereof.The diamond electrode comprises a surrounding basket and conductive diamond particles, holes are formed in the surrounding basket to form a net-shaped surrounding basket, and the hole diameter of the holes is smaller than the particle diameter of the conductive diamond particles; and the conductive diamond particles are placed in the enclosure basket. The preparation method of the diamond electrode comprises the following steps: preparing the conductive diamond particles; preparing a surrounding basket; and the conductive diamond particles are placed in a surrounding basket, the surrounding basket limits the stacking shape of the conductive diamond particles, and the diamond electrode is manufactured. The diamond electrode has the advantages that the diamond electrode has a large specific surface area, the interior of the diamond electrode can be detached for cleaning, the diamond electrode can be reused through installation after cleaning is completed, and the performance of the diamond electrode cannot be damaged.

Description

Technical Field

[0001] The present application relates to the technical field of electrode preparation, and in particular to a diamond electrode and a preparation method thereof. Background Art

[0002] In the field of environmental electrochemistry, doped diamond has become a research hotspot because of its extremely high oxygen evolution potential, extremely low background current and extremely wide electrochemical window, as well as its surface inertness, weak adsorption and chemical stability. It is often used as an "ideal electrode material" and is applied to the treatment of difficult-to-biodegrade organic wastewater with high concentration, high salinity, high ammonia nitrogen and strong acidity and alkalinity.

[0003] In the prior art, most of the traditional diamond electrodes made of doped diamond are two-dimensional electrodes, so their specific surface area is relatively low, which restricts the mass transfer efficiency on the surface of the diamond electrode. At the same time, most of the traditional diamond electrodes are closed as a whole. When the diamond electrode is blocked or poisoned, it is difficult to clean it, and the same diamond electrode cannot be used in a variety of working conditions, so it is not conducive to exerting its best mass transfer efficiency and is not flexible enough. In addition, the preparation cost of traditional diamond electrodes is relatively high, which is not conducive to large-scale industrial production.

[0004] Therefore, there is an urgent need for a diamond electrode with a high specific surface area, easy cleaning, applicable to a variety of working conditions and low preparation cost to solve the problems existing in the prior art. Summary of the invention

[0005] In order to solve at least one of the above technical problems, a diamond electrode with high specific surface area, easy cleaning, applicability to a variety of working conditions and low preparation cost is developed. The present application provides a diamond electrode and a preparation method thereof.

[0006] On the one hand, the present application provides a diamond electrode, comprising a basket and conductive diamond particles, wherein the basket is provided with holes to form a mesh basket, and the hole diameter of the holes is smaller than the particle diameter of the conductive diamond particles; the conductive diamond particles are placed in the basket.

[0007] By adopting the above technical solution, the diamond electrode provided by the present application is constructed by placing conductive diamond particles inside the basket, so that the conductive diamond particles and the basket are detachably arranged. That is, in the diamond electrode provided by the present application, the fixed connection between each conductive diamond particle and between each conductive diamond particle and the basket is replaced by directly placing conductive diamond particles, so that the conductive diamond particles and between each conductive diamond particle and the basket can be separated, so that each conductive diamond particle can be removed from the basket and then the conductive diamond particles and the basket can be cleaned, thereby cleaning the inside of the diamond electrode, which can effectively alleviate the phenomenon of electrode blockage and electrode poisoning. At the same time, after cleaning the conductive diamond particles and the basket, the cleaned conductive diamond particles can be placed back in the cleaned basket to reuse the diamond electrode, thereby overcoming the defect in the prior art that it is difficult to clean the inside of the diamond electrode when the traditional diamond electrode is arranged in a monolithic manner.

[0008] At the same time, the diamond electrode provided by the present application uses a basket to restrict the shape and position of the conductive diamond particles, so that the conductive diamond particles can be stacked on each other to form a three-dimensional electrode, which greatly increases the specific surface area of ​​the diamond electrode provided by the present application; in addition, the basket used by the diamond electrode provided by the present application has holes, and pores can also be formed by stacking between the conductive diamond particles. The pores and the holes on the basket can be used together for mass transfer, which can improve the mass transfer efficiency of the diamond electrode provided by the present application, and can also further increase the specific surface area of ​​the diamond electrode provided by the present application, thereby overcoming the defects of the conventional diamond electrode in the prior art that the specific surface area is low and the mass transfer efficiency is low when it is a two-dimensional electrode; and because the working part of the diamond electrode provided by the present application is formed by the stacking of individual conductive diamond particles, it can effectively avoid the difficulty in preparing a large-area diamond electrode due to the monolithic setting of the diamond electrode.

[0009] In addition, by placing conductive diamond particles, the diamond electrode provided in the present application can become a flexible electrode. By changing the shape of the basket and the number of placed conductive diamond particles, the use scenarios of the diamond electrode provided in the present application can be varied and can be applied to different working conditions. Therefore, the diamond electrode provided in the present application is more flexible.

[0010] Optionally, the conductive diamond particles include at least one of heterogeneous material substrate particles, diamond substrate particles and doped diamond particles; wherein the surfaces of the heterogeneous material substrate particles and the diamond substrate particles are both deposited with doped diamond coatings.

[0011] By adopting the above technical solution, the working part of the monolithic diamond electrode is converted into independent conductive diamond particles that can be separated from each other, and the conductive diamond particles in the diamond electrode provided by the present application can be prepared separately, thereby converting the preparation of the monolithic diamond electrode into the preparation of each conductive diamond particle, which can further effectively overcome the area limitation when depositing the doped diamond coating, thereby realizing the preparation of large-area diamond electrodes.

[0012] Optionally, the conductive diamond particles have a particle size of 0.5 to 15 mm.

[0013] By adopting the above technical solution, the size of the conductive diamond particles used in the diamond electrode provided by the present application is limited. The size of the conductive diamond particles is relatively large, so that when the conductive diamond particles placed in the basket are stacked with each other, the conductive diamond particles are not completely in contact with each other, but a large number of macroscopic pores are formed. The macroscopic pores can realize mass transfer, thereby improving the specific surface area and mass transfer efficiency of the diamond electrode provided by the present application, and the size of the macroscopic pores can be controlled by adjusting the size of the conductive diamond particles.

[0014] Optionally, the doped diamond coating is a coating I of micron-scale doped diamond grains or a coating I of nano-scale doped diamond grains.

[0015] By adopting the above technical solution, the type of doped diamond coating deposited on the surface of some conductive diamond particles used in the diamond electrode provided by the present application is limited. The doped diamond coating is used as a functional layer, which can further better utilize the electrochemical properties of doped diamond to achieve conductivity, and can also enable the diamond electrode provided by the present application to have a wider potential window, thereby achieving the degradation of difficult-to-degrade pollutants.

[0016] Further optionally, the doped diamond coating is the coating I of the micron-sized doped diamond grains, and the surface of the coating I of the micron-sized doped diamond grains has micro-pits I.

[0017] By adopting the above technical solution, when the doped diamond coating is further limited to a coating I of micron-sized doped diamond grains, the surface of the doped diamond coating also has micro-pits I, which can make the surface of the conductive diamond particles used in the diamond electrode provided by the present application have more micro-pits, thereby increasing the specific surface area of ​​the conductive diamond particles, thereby further improving the specific surface area of ​​the diamond electrode provided by the present application.

[0018] Further optionally, the doped diamond coating is a coating I of nanoscale doped diamond grains, and the coating I of nanoscale doped diamond grains is a porous structure I.

[0019] By adopting the above technical solution, the doped diamond coating is further limited to a coating I of nano-scale doped diamond grains and a porous structure I. At this time, compared with the coating I of micron-scale doped diamond grains, the size of the doped diamond grains inside the doped diamond coating is smaller, so that the surface of the conductive diamond particles has more microscopic pores, and the specific surface area of ​​the conductive diamond particles is larger, thereby further improving the specific surface area of ​​the diamond electrode provided in the present application.

[0020] Optionally, the doped diamond coating includes a first coating and a second coating, the first coating is a coating II of micron-scale doped diamond grains, the second coating is a coating II of nano-scale doped diamond grains, and the second coating is deposited on the first coating; the surface of the first coating has micro-pits II, and the second coating is a porous structure II.

[0021] By adopting the above technical solution, the doped diamond coating is arranged into a two-layer structure, and the coating II of nano-scale doped diamond grains is arranged on the coating II of micron-scale doped diamond grains, that is, the coating II of micron-scale doped diamond grains is used as a transition layer for the coating II of nano-scale doped diamond grains to be deposited on the surface of heterogeneous material substrate particles or diamond substrate particles, which can effectively improve the film-base adhesion of the coating II of nano-scale doped diamond grains; at the same time, by exposing the coating II of nano-scale doped diamond grains on the outer surface, smaller-sized doped diamond grains are exposed, so that the surface of the conductive diamond particles has more microscopic pores, which can increase the specific surface area of ​​the conductive diamond particles, thereby further improving the specific surface area of ​​the diamond electrode provided in the present application.

[0022] Optionally, the resistivity ρ(basket) of the enclosure and the resistivity ρ(conductive diamond particles) of the conductive diamond particles satisfy the following relationship: ρ(basket)≥ρ(conductive diamond particles).

[0023] By adopting the above technical solution, the resistivity of the basket and the conductive diamond particles in the diamond electrode provided by the present application is controlled to satisfy a specific relationship, thereby avoiding the situation where the current preferentially passes through the basket and causes the basket to be conductive when the diamond electrode provided by the present application is in use, thereby avoiding the phenomenon of the potential window of the diamond electrode provided by the present application being reduced and the electrochemical corrosion of the basket, thereby achieving the function of the basket only to limit the shape and position of the accumulation of the conductive diamond particles, and the basket thereby limits the overall shape of the diamond electrode provided by the present application.

[0024] In a second aspect, the present application provides a method for preparing the above-mentioned diamond electrode, comprising the following steps: S1, preparing a basket; preparing conductive diamond particles; S2. Placing the conductive diamond particles in the enclosure basket, wherein the enclosure basket defines the shape of the conductive diamond particles stacked to obtain a diamond electrode.

[0025] By adopting the above technical scheme, firstly, each conductive diamond particle used in the diamond electrode provided by the present application is prepared separately, thereby overcoming the defect in the prior art that it is difficult to prepare a monolithic diamond electrode with a large area; secondly, the prepared conductive diamond particles are placed inside the basket so that each conductive diamond particle contacts each other, thereby achieving connectivity between each conductive diamond particle, so that the diamond electrode provided by the present application can play the role of an electrode; thirdly, the basket limits the shape of the accumulation of conductive diamond particles, so that the diamond electrode provided by the present application becomes a three-dimensional electrode, so that the diamond electrode prepared by the preparation method of the diamond electrode provided by the present application has a high specific surface area; fourthly, the basket only limits the shape of the accumulation of conductive diamond particles, and does not adopt a method of fixed connection between each other, so that each conductive diamond particle inside the basket can be taken out and cleaned, thereby overcoming the problem in the prior art that it is difficult to clean the diamond electrode.

[0026] Optionally, in step S1, preparing the conductive diamond particles comprises: preparing at least one of heterogeneous material substrate particles with a doped diamond coating deposited on the surface, preparing diamond substrate particles with a doped diamond coating deposited on the surface, and preparing doped diamond particles.

[0027] By adopting the above technical solution, different types of conductive diamond particles can be selected according to specific working conditions; at the same time, each conductive diamond particle can be prepared separately, thereby effectively overcoming the limitation of the deposition area of ​​the diamond coating caused by the integral setting of the diamond electrode, thereby realizing the preparation of large-area diamond electrodes.

[0028] Optionally, preparing the heterogeneous material substrate particles with the doped diamond coating deposited on the surface comprises: Step 1: taking a heterogeneous material substrate particle and pre-placing a diamond seed crystal on the surface of the heterogeneous material substrate particle; Step 2: using chemical vapor deposition and introducing doping elements into the deposition atmosphere used in the chemical vapor deposition method, depositing a doped diamond coating on the surface of the heterogeneous material substrate particles, thereby obtaining heterogeneous material substrate particles with the doped diamond coating deposited on the surface.

[0029] By adopting the above technical scheme, firstly, diamond seed crystals are pre-placed on the surface of heterogeneous material substrate particles, which can improve the surface roughness of heterogeneous material particles and the nucleation density of doped diamond coating, thereby enhancing the film-base adhesion of doped diamond coating on heterogeneous material substrate particles; secondly, chemical vapor deposition is selected to deposit doped diamond coating, which can achieve deposition of doped diamond coating on the surface of heterogeneous material substrate particles, thereby completely covering the surface of heterogeneous material substrate particles, avoiding exposure of the base material of heterogeneous material substrate particles, thereby corrosion and shedding of doped diamond coating; thirdly, introduction of doping elements can achieve the purpose of conductivity of doped diamond coating, so that electrochemical reaction occurs on the surface of doped diamond coating, thereby generating hydroxyl radicals to achieve oxidation or electrolysis of pollutants that are difficult to degrade.

[0030] Further optionally, in the step one, the operation of pre-placing diamond seed crystals on the surface of the heterogeneous material substrate particles includes: cleaning the heterogeneous material substrate particles; placing the cleaned heterogeneous material substrate particles in a diamond powder suspension, ultrasonically treating them, and pre-placing diamond seed crystals on the surface of the heterogeneous material substrate particles; in the diamond powder suspension, the mass fraction of diamond powder with a particle size of 3 to 5 μm is 40 to 60%, and the mass fraction of diamond powder with a particle size of 35 to 45 μm is 40 to 60%, and the solvent is anhydrous ethanol.

[0031] By adopting the above technical solution, the surface of the heterogeneous material substrate particles is cleaned and diamond seed crystals are pre-placed, so that the nucleation density of the doped diamond coating can be increased during the subsequent deposition of the doped diamond coating, thereby enhancing the film-base adhesion of the doped diamond coating on the heterogeneous material substrate particles.

[0032] Optionally, preparing the diamond substrate particles with the doped diamond coating deposited on the surface comprises: Step 1, taking diamond substrate particles; Step 2: using chemical vapor deposition and introducing doping elements into the deposition atmosphere used in the chemical vapor deposition method, depositing a doped diamond coating on the surface of the diamond substrate particles, and obtaining diamond substrate particles with the doped diamond coating deposited on the surface.

[0033] By adopting the above technical scheme, firstly, chemical vapor deposition is used to deposit the doped diamond coating, so that the doped diamond coating can completely cover the surface of the diamond substrate particles and form a whole, thereby avoiding the phenomenon of short circuit caused by the contact between the diamond substrate particles; secondly, the introduction of doping elements can achieve the purpose of conductivity of the doped diamond coating, so that the surface of the doped diamond coating undergoes an electrochemical reaction, thereby generating hydroxyl radicals to achieve oxidation or electrolysis of pollutants that are difficult to degrade.

[0034] Optionally, the chemical vapor deposition method is selected from DC arc plasma jet chemical vapor deposition method, and the doping element is selected from B.

[0035] By adopting the above technical solution, the chemical vapor deposition method is further optimized as a DC arc plasma jet chemical vapor deposition method, which can effectively improve the growth rate of the doped diamond coating; the doping element is further optimized as a low-energy level doping element B, which can make the deposited doped diamond coating have the characteristics of low resistivity. In addition, the deposited doped diamond coating can also have the ability of metallic properties under the condition of a higher B doping amount.

[0036] Optionally, the parameters of the DC arc plasma jet chemical vapor deposition method are as follows: In the deposition atmosphere: the hydrogen flow rate is 6 to 10 SLM, the argon flow rate is 2.5 to 6 SLM, and the methane flow rate is CH4 / H2=1 to 2%, forming a CH4 / H2 / Ar deposition atmosphere; B is introduced into the CH4 / H2 / Ar deposition atmosphere, and the B doping amount is B / C=3000 to 15000 ppm; the deposition temperature is 780 to 950°C, and the deposition pressure is 2.5 to 4.5 kPa; at this time, the doped diamond coating is deposited, and the doped diamond coating is a coating I of micron-level doped diamond grains.

[0037] By adopting the above technical solution, a lower methane flow rate and a higher deposition temperature are controlled to achieve the deposition of coating I of micron-sized doped diamond grains.

[0038] Optionally, after the deposition is completed, the introduction of methane and B in the CH4 / H2 / Ar deposition atmosphere is suspended to form a H2 / Ar etching atmosphere; in the H2 / Ar etching atmosphere: the hydrogen flow rate is 6 to 10 SLM, the argon flow rate is 2.5 to 5 SLM; the etching temperature is 750 to 1050°C, the etching pressure is 2.8 to 4.5 kPa, and the etching time is 5 to 30 min; at this time, the surface of the coating Ⅰ of the micron-sized doped diamond grains obtained by deposition has micro-pits Ⅰ.

[0039] By adopting the above technical solution, the introduction of methane and B in the deposition atmosphere are suspended, so that the surface of the coating Ⅰ of the deposited micron-sized doped diamond grains can be subjected to hydrogen plasma etching. The size of the micron-sized doped diamond grains is relatively large, the graphite content between the grains is relatively low, and the etching temperature and etching time are relatively long. Therefore, when the hydrogen plasma etching treatment is performed, the atomic distortion area around the outcropping of the dislocation on the surface of the micron-sized doped diamond grains is etched, thereby forming micro-etching pits Ⅰ, increasing the specific surface area of ​​the conductive diamond particles, thereby further improving the specific surface area of ​​the diamond electrode provided in the present application.

[0040] Optionally, the parameters of the DC arc plasma jet chemical vapor deposition method are as follows: In the deposition atmosphere: the hydrogen flow rate is 7 to 9 SLM, the argon flow rate is 2.5 to 5 SLM, and the methane flow rate is CH4 / H2=4 to 8%, forming a CH4 / H2 / Ar deposition atmosphere; B is introduced into the CH4 / H2 / Ar deposition atmosphere, and the B doping amount is B / C=3000 to 12000 ppm; the deposition temperature is 700 to 820°C, and the deposition pressure is 2.5 to 4.5 kPa; at this time, the doped diamond coating is deposited, and the doped diamond coating is a coating I of nanoscale doped diamond grains.

[0041] By adopting the above technical solution, a higher methane flow rate and a lower deposition temperature are controlled to achieve the deposition of coating I of nano-scale doped diamond grains.

[0042] Optionally, during the deposition process, after 5 to 15 minutes of deposition, the introduction of methane and B are suspended in the CH4 / H2 / Ar deposition atmosphere to form a H2 / Ar etching atmosphere, and hydrogen plasma etching is performed, and the etching time is 1 / 4 to 1 / 3 of the deposition time; after the etching is completed, methane is continued to be introduced into the H2 / Ar etching atmosphere and B is introduced, and deposition and etching are performed alternately; at this time, the coating I of the nanoscale doped diamond grains obtained by deposition is a porous structure I.

[0043] By adopting the above technical scheme, the introduction of methane and the introduction of B are suspended in the deposition atmosphere, and the introduction of methane and the introduction of B are alternately performed, so that in the process of growing the coating layer I of nano-scale doped diamond grains, chemical vapor deposition and hydrogen plasma etching are alternately performed. The size of the nano-scale doped diamond grains is relatively small, and the content of graphite between each grain is relatively high. Therefore, when the hydrogen plasma etching treatment is performed, the graphite between each nano-scale doped diamond grain is etched, so that the content of graphite is reduced, thereby increasing the potential window; at the same time, holes are also formed in the coating layer I of the nano-scale doped diamond grains. Therefore, the coating layer I of the nano-scale doped diamond grains finally obtained is a porous structure I, which can increase the specific surface area of ​​the conductive diamond particles, thereby further improving the specific surface area of ​​the diamond electrode provided in the present application.

[0044] Optionally, the DC arc plasma jet chemical vapor deposition method comprises the following steps: A1. In the deposition atmosphere, the hydrogen flow rate is 6-10 SLM, the argon flow rate is 2.5-6 SLM, and the methane flow rate is CH4 / H2=1-2%, forming a CH4 / H2 / Ar deposition atmosphere; B is introduced into the CH4 / H2 / Ar deposition atmosphere, and the B doping amount is B / C=3000-15000 ppm; the deposition temperature is 780-950°C, and the deposition pressure is 2.5-4.5 kPa; A2, suspending the introduction of methane and B to form a H2 / Ar etching atmosphere; in the H2 / Ar etching atmosphere: the hydrogen flow rate is 6-10SLM, the argon flow rate is 2.5-5SLM; the etching temperature is 750-1050°C, the etching pressure is 2.8-4.5kPa, and the etching time is 5-30min; A3, continue to introduce methane and introduce B to form a CH4 / H2 / Ar deposition atmosphere; in the CH4 / H2 / Ar deposition atmosphere, the hydrogen flow rate is 7-9SLM, the argon flow rate is 2.5-5SLM, the methane flow rate is CH4 / H2=4-8%, and the B doping amount is B / C=3000-12000ppm; the deposition temperature is 700-820°C, the deposition pressure is 2.5-4.5kPa, and the deposition time is 5-15min; A4, suspend the introduction of methane and B, form an H2 / Ar etching atmosphere, perform hydrogen plasma etching, and the etching time is 1 / 4 to 1 / 3 of the deposition time; return to step A3 to perform deposition and etching alternately; At this time, the doped diamond coating is deposited, and the doped diamond coating includes a first coating and a second coating, the first coating is a coating II of micron-scale doped diamond grains, the second coating is a coating II of nano-scale doped diamond grains, and the second coating is deposited on the first coating; the surface of the first coating has micro-pits II, and the second coating is a porous structure II.

[0045] By adopting the above technical scheme, first, a coating layer II of micron-sized doped diamond grains is deposited, and the surface of the deposited coating layer II of micron-sized doped diamond grains is etched to obtain a first coating layer having micro-pits II on the surface; then, the first coating layer is used as a transition layer for the second coating layer, and a coating layer II of nano-sized doped diamond grains having a porous structure II is deposited, thereby effectively improving the film-base adhesion of the second coating layer, and at the same time, smaller-sized doped diamond grains are exposed on the outer surface, so that the surface of the conductive diamond particles has more microscopic pores, thereby increasing the specific surface area of ​​the conductive diamond particles, thereby further improving the specific surface area of ​​the diamond electrode provided in the present application.

[0046] In summary, the present invention includes at least one of the following beneficial technical effects: 1. The diamond electrode provided in the present application is constructed by placing conductive diamond particles inside a basket, so that the conductive diamond particles and the basket are detachably arranged, thereby enabling separation between the conductive diamond particles and between the conductive diamond particles and the basket, that is, after removing the conductive diamond particles from the basket, the conductive diamond particles and the basket can be cleaned, thereby achieving cleaning of the inside of the diamond electrode, and after cleaning, the cleaned conductive diamond particles can be placed back in the cleaned basket for reuse, thereby overcoming the defect in the prior art that it is difficult to clean the inside of the diamond electrode when the traditional diamond electrode is arranged in an integral block.

[0047] 2. In the diamond electrode provided in the present application, the basket restricts the shape and position of the conductive diamond particles, so that the conductive diamond particles can be stacked on each other to form a three-dimensional electrode, which greatly increases the specific surface area of ​​the diamond electrode provided in the present application.

[0048] 3. In the diamond electrode provided in the present application, there are holes on the surrounding basket, and pores are formed by accumulation between the conductive diamond particles. The pores and the holes on the surrounding basket can be used together for mass transfer, so that when the diamond electrode provided in the present application is used to treat the liquid, the liquid can enter the interior of the diamond electrode through the above-mentioned holes and pores, thereby improving the mass transfer efficiency of the diamond electrode provided in the present application, greatly increasing the contact area between the liquid and the diamond electrode provided in the present application, and further increasing the specific surface area of ​​the diamond electrode provided in the present application, thereby overcoming the defect of low specific surface area of ​​the traditional diamond electrode in the prior art when it is a two-dimensional electrode.

[0049] 4. In the diamond electrode provided in the present application, the placement of conductive diamond particles can make the diamond electrode provided in the present application a flexible electrode. The shape of the surrounding basket and the number of placed conductive diamond particles can also be changed to make the use scenarios of the diamond electrode provided in the present application varied and can be applied to different working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Figure 1 Schematic diagram of the structure of the diamond electrode provided in Example 1.

[0051] Figure 2 This is an electron microscope image (micron crystal) of the surface of silicon particles with a doped diamond coating deposited on the surface provided in Preparation Example 3.

[0052] Figure 3 This is an electron microscope image of the surface of silicon particles with a doped diamond coating deposited on the surface provided in Preparation Example 13 (micron crystal + etching).

[0053] Figure 4This is an electron microscope image of the surface of silicon particles with a doped diamond coating deposited on the surface provided in Preparation Example 19; (nanocrystal).

[0054] Figure 5 This is an electron microscope image of the surface of silicon particles with a doped diamond coating deposited on the surface provided in Preparation Example 28 (nanoporous).

[0055] Figure 6 This is an electron microscope image of the surface of silicon particles with a doped diamond coating deposited on the surface provided in Preparation Example 32 (microcrystalline + nanoporous).

[0056] Explanation of the accompanying drawings: 1. basket; 2. conductive diamond particles. DETAILED DESCRIPTION

[0057] The present application is further described in detail below with reference to the accompanying drawings and embodiments.

[0058] The present application designs a diamond electrode, including a basket 1 and conductive diamond particles 2. The basket 1 is provided with holes to form a mesh basket. The hole diameter is smaller than the particle diameter of the conductive diamond particles 2. The conductive diamond particles 2 are placed in the basket 1.

[0059] The diamond electrode of the present application is prepared by the following method, comprising the following steps: S1, preparing a basket 1; preparing conductive diamond particles 2; S2. Placing the conductive diamond particles 2 in the surrounding basket 1. The surrounding basket 1 defines the shape of the conductive diamond particles 2 to obtain a diamond electrode.

[0060] The inventors of the present application found that the existing diamond electrodes are usually set up in a closed whole block when improving the electrode material. The defects of the diamond electrodes with such a setting are: when the diamond electrode is blocked or poisoned, it is difficult to disassemble and clean the inside, or it is difficult to reinstall and reuse the inside after disassembly and cleaning, and the performance of the cleaned diamond electrode is easily damaged. At the same time, during the preparation process of the diamond electrode with such a setting, due to the limitation of the deposition size, the specific surface area and size of such diamond electrodes are small.

[0061] Therefore, the applicant has designed the diamond electrode provided in this application from the perspective that the diamond electrode can be cleaned, reused after cleaning and will not be damaged, that is, the diamond electrode is designed in the form of placing conductive diamond particles 2 in the enclosure basket 1, so that the inside of the diamond electrode can be disassembled. At the same time, the use of the enclosure basket 1 to limit the stacking shape of the conductive diamond particles 2 can also further overcome the defect of low specific surface area when most diamond electrodes in the prior art are two-dimensional electrodes. The reason is that in the diamond electrode provided by this application, the conductive diamond particles 2 are stacked on each other to form a three-dimensional electrode, and pores are formed between each conductive diamond particle 2, which cooperate with the holes opened on the enclosure basket 1, so that when the diamond electrode provided by this application processes the liquid, the liquid can pass through the inside of the diamond electrode, further improving the mass transfer efficiency, greatly improving the contact area between the liquid and the diamond electrode, and realizing the increase of the specific surface area of ​​the diamond electrode. Specific embodiments

[0062] In the preparation examples and embodiments, the "deposition atmosphere" refers to the atmosphere formed by the gases introduced during chemical vapor deposition.

[0063] When the electrode performance of the diamond electrode provided in the embodiment of the present application is tested, the test items and test methods are as follows: 1. Resistivity: When the conductive diamond particles 2 are selected from heterogeneous material substrate particles or diamond substrate particles with a doped diamond coating deposited on the surface, the four-point probe method is used for measurement, and the operation is as follows: for the convenience of measurement, a test sample is placed in a deposition chamber, and the doped diamond coating is deposited synchronously with the heterogeneous material substrate particles or diamond substrate particles. After the deposition is completed, the resistivity of the doped diamond coating on the surface of the test sample is measured by the four-point probe method; wherein the material of the test sample is the same as that of the heterogeneous material substrate particles or diamond substrate particles used for deposition, and the size of the test sample is 5 mm×5 mm; When the conductive diamond particles 2 are selected from doped diamond particles, the resistivity test method of the whole material is adopted, and the operation is as follows: the doped diamond particles are taken, cut and polished to make diamond sheets with parallel upper and lower surfaces, and the current in the circuit is tested by applying voltage on the upper and lower surfaces, and the formula is used. Calculated; where S is the cross-sectional area of ​​the diamond sheet, and L is the thickness of the diamond sheet; 2. Specific surface area: The specific surface area of ​​the diamond electrode is expressed as the effective active area per unit volume of the electrode, which is calculated using the chronocoulometry method. The test solution is 0.1M KCl / 0.1mM K3[Fe(CN)6]; 3. Potential window of aqueous solution: measured by current-cyclic voltammetry scanning method, the working electrode is a diamond electrode, the auxiliary electrode is a Pt electrode, the reference electrode is a saturated calomel electrode, the solution is 0.2M Na2SO4, and the cyclic scanning rate is 0.1V / s.

[0064] The following are Preparation Examples 1 to 57 and Examples 1 to 71 of the present application. Preparation Examples 1 to 43 respectively provide a heterogeneous material substrate particle with a doped diamond coating deposited on the surface, and Examples 1 to 49 respectively provide a diamond electrode prepared using the above-mentioned heterogeneous material substrate particles with a doped diamond coating deposited on the surface.

[0065] Preparation Examples 1 to 10 Preparation Examples 1 to 10 respectively provide a heterogeneous material substrate particle having a coating layer I with micron-sized doped diamond grains deposited on the surface.

[0066] Preparation Example 1 Select silicon blocks, crush them and then screen them, and select silicon particles with an average particle size of 0.5 mm and an octahedral shape as heterogeneous material substrate particles; The silicon particles are cleaned and placed in a diamond powder suspension for ultrasonic treatment for 45 minutes, and diamond seed crystals are pre-placed on the surface of the silicon particles; in the diamond powder suspension, the mass fraction of diamond powder with a particle size of 5 μm is 50%, the mass fraction of diamond powder with a particle size of 40 μm is 50%, and the solvent is anhydrous ethanol; Silicon particles with diamond seed crystals pre-placed on the surface are placed in a DC arc plasma jet chemical vapor deposition chamber to deposit a coating I of micron-sized doped diamond grains; specifically, the parameters selected are as follows: The hydrogen flow rate is 10SLM, the argon flow rate is 2.5SLM, and the methane flow rate is CH4 / H2=1%, forming a CH4 / H2 / Ar deposition atmosphere; the doping element B is introduced into the CH4 / H2 / Ar deposition atmosphere, the source of B is selected from diborane, and the B doping amount is B / C=3000ppm; the deposition temperature is 780°C, the deposition pressure is 2.5kPa, and when the thickness of the deposited coating I of micron-sized doped diamond grains is 5μm, the deposition is stopped to obtain conductive diamond particles 2, which are silicon particles with a coating I of micron-sized doped diamond grains deposited on the surface.

[0067] Preparation Examples 2 to 5 Based on Preparation Example 1, the difference between Preparation Examples 2 to 5 and Preparation Example 1 is that different parameters are used when depositing the coating layer I of micron-sized doped diamond grains; the remaining steps, conditions and parameters are consistent with those in Preparation Example 1. Specifically, the parameters selected for Preparation Examples 2 to 5 are shown in Table 1.

[0068] Table 1 Summary of parameters of preparation examples 2 to 5 Preparation Example 2 Preparation Example 3 Preparation Example 4 Preparation Example 5 Hydrogen flow / SLM 7.8 8 7.2 6 Argon flow / SLM 3.5 3 4 6 Methane flow / % <![CDATA[CH4 / H2=1.3]]> <![CDATA[CH4 / H2=1.5]]> <![CDATA[CH4 / H2=1.8]]> <![CDATA[CH4 / H2=2]]> B doping amount / ppm B / C=6000 B / C=9000 B / C=12000 B / C=15000 Deposition temperature / ℃ 800 820 850 950 Deposition pressure / kPa 3.5 3.3 4 4.5 Preparation Example 6 Based on Preparation Example 1, the difference between this Preparation Example and Preparation Example 1 is that when depositing the coating layer I of micron-sized doped diamond grains, the chemical vapor deposition method used in this Preparation Example is different, and the specific operation is as follows: The silicon particles with diamond seed crystals pre-placed on the surface are placed in a microwave plasma chemical vapor deposition chamber to deposit a coating I of micron-sized doped diamond grains; specifically, the parameters selected are as follows: The hydrogen flow rate is 0.5 SLM, and the methane flow rate is CH4 / H2=1.5%, forming a CH4 / H2 deposition atmosphere; a doping element B is introduced into the CH4 / H2 deposition atmosphere, the source of B is selected from diborane, and the B doping amount is B / C=8000 ppm; the deposition temperature is 800° C., the deposition pressure is 4.0 kPa, and when the thickness of the deposited coating Ⅰ of micron-sized doped diamond grains is 5 μm, the deposition is stopped to obtain conductive diamond particles 2, wherein the conductive diamond particles 2 are silicon particles with a coating Ⅰ of micron-sized doped diamond grains deposited on the surface; The remaining steps, conditions and parameters are consistent with those in Preparation Example 1.

[0069] Examples 1 to 10 Examples 1 to 10 respectively provide a diamond electrode made from silicon particles having a coating I with micron-sized doped diamond grains deposited on the surface.

[0070] Example 1 The silicon particles prepared in Preparation Example 1 and having a coating layer Ⅰ deposited with micrometer-sized doped diamond grains on the surface are selected as conductive diamond particles 2; A polyethylene resin is selected and the polyethylene resin is woven into a basket 1, wherein the diameter of the holes on the basket 1 is smaller than the diameter of the conductive diamond particles 2; since the basket 1 is made of polyethylene resin, the basket 1 can be a flexible basket; See also Figure 1 The diamond electrode includes a basket 1 and conductive diamond particles 2 placed in the basket 1: the conductive diamond particles 2 are placed in the basket 1, and the basket 1 is used to limit the stacking shape of the conductive diamond particles 2 so that the conductive diamond particles 2 are in contact with each other, and the conductive diamond particles 2 are vibrated to achieve close contact between the conductive diamond particles 2, thereby obtaining a diamond electrode.

[0071] Embodiments 2 to 6 Based on Example 1, the difference between Examples 2 to 6 and Example 1 lies in the selection of conductive diamond particles 2, see Table 2; the remaining steps, conditions and parameters are consistent with those in Example 1.

[0072] Table 2 Selection of conductive diamond particles in Examples 2 to 6 Selected conductive diamond particles Example 2 Preparation Example 2 Example 3 Preparation Example 3 Example 4 Preparation Example 4 Example 5 Preparation Example 5 Example 6 Preparation Example 6 The electrode performance of the diamond electrodes provided in Examples 1 to 6 was tested, and the test results are recorded in Table 3.

[0073] Table 3 Summary of test results of Examples 1 to 6 Resistivity / mΩ·cm <![CDATA[Specific surface area / cm -1 > Aqueous solution potential window / V Example 1 45.2 45.1 3.4 Example 2 14.8 47.4 3.6 Example 3 8.5 52.3 3.6 Example 4 3.1 45.8 3.5 Example 5 2.6 43.8 3.3 Example 6 6.1 48.4 3.6 As shown in Table 3, the specific surface area of ​​the diamond electrodes provided in Examples 1 to 6 is 43.5 cm -1 As for the resistivity, the resistivity of Example 1 is larger than that of Examples 2 to 6. The reason is that the resistivity is mainly determined by the amount of boron doping. When the amount of boron doping is low, the influence on the resistivity of the diamond electrode is greater. When the amount of boron doping reaches a certain value, the amount of boron doping is basically saturated. At this time, the influence on the resistivity of the diamond electrode is small. Therefore, as the amount of boron doping increases, the rate of change of resistivity is greatly reduced. However, according to the results of Table 3, the diamond electrodes provided by Examples 1 to 6 still have good comprehensive performance.

[0074] Specifically, although the diamond electrode provided in Example 6 has better comprehensive performance, the conductive diamond particles 2 used in the diamond electrode provided in Example 6 are conductive diamond particles 2 deposited by microwave plasma chemical vapor deposition. Compared with the conductive diamond particles 2 deposited by DC arc plasma jet chemical vapor deposition in the diamond electrodes provided in Examples 1 to 5, the growth rate of the coating Ⅰ of micron-sized doped diamond grains is slower, so the DC arc plasma jet chemical vapor deposition method is superior; in addition, in Examples 1 to 5, the comprehensive performance of the diamond electrode provided in Example 3 is better, that is, the performance of the diamond electrode prepared using the conductive diamond particles 2 prepared in Preparation Example 3 is better.

[0075] Preparation Examples 7 to 10 Based on Preparation Example 3, the difference between Preparation Examples 7 to 10 and Preparation Example 3 is that the thickness of the coating I of the micron-sized doped diamond grains deposited in Preparation Examples 7 to 10 is different. In Preparation Examples 7 to 10, the deposition is stopped when the thickness of the deposited coating I of the micron-sized doped diamond grains is 2.5 μm, 7.5 μm, 10 μm and 15 μm, respectively; the remaining steps, conditions and parameters are the same as those in Preparation Example 3.

[0076] Embodiments 7 to 10 Based on Example 3, the difference between Examples 7 to 10 and Example 3 lies in the selection of conductive diamond particles 2, see Table 4; the remaining steps, conditions and parameters are consistent with those in Example 3.

[0077] Table 4 Selection of conductive diamond particles in Examples 7 to 10 Selected conductive diamond particles Example 7 Preparation Example 7 Example 8 Preparation Example 8 Example 9 Preparation Example 9 Example 10 Preparation Example 10 The electrode performance of the diamond electrodes provided in Examples 7 to 10 was tested, and the test results are recorded in Table 5.

[0078] Table 5 Summary of test results of Examples 7 to 10 Resistivity / mΩ·cm <![CDATA[Specific surface area / cm -1 > Aqueous solution potential window / V Example 7 8.5 51.8 3.5 Example 8 8.6 52.2 3.6 Example 9 8.6 52.1 3.6 Example 10 8.6 52.2 3.6 Referring to Table 5, it can be seen from the results of Table 5 that when using heterogeneous material substrate particles with the same average particle size, the resistivity, specific surface area and aqueous solution potential window of the diamond electrode do not change significantly with the increase in the thickness of the coating Ⅰ of micron-sized doped diamond grains deposited on the surface of the heterogeneous material substrate particles. By comparing the test results of Example 3 and Examples 7 to 10, it can be seen that the diamond electrode provided by Example 3 has the largest specific surface area, the lowest resistivity, and the largest aqueous solution potential window, and the electrode has better comprehensive performance, that is, the performance of the diamond electrode prepared using the conductive diamond particles 2 prepared in Preparation Example 3 is better.

[0079] Preparation Examples 11 to 16 Preparation Examples 11 to 16 respectively provide a heterogeneous material substrate particle having a coating layer I with micron-sized doped diamond grains deposited on the surface, and micro-pits I on the surface of the coating layer I with micron-sized doped diamond grains.

[0080] Preparation Example 11 Based on Preparation Example 3, the difference between this Preparation Example and Preparation Example 3 is that after the deposition of the coating layer I of micron-sized doped diamond grains is completed, the coating layer I of micron-sized doped diamond grains is further subjected to hydrogen plasma etching. The specific operation is as follows: After the deposition is completed, the introduction of methane and B is suspended in the CH4 / H2 / Ar deposition atmosphere to form a H2 / Ar etching atmosphere: the hydrogen flow rate is 6SLM, the argon flow rate is 5SLM; the etching temperature is 750°C, the etching pressure is 2.8kPa, and the etching time is 30min; at this time, the surface of the coating Ⅰ of micron-sized doped diamond grains deposited on the surface of the silicon particles has micro-pits Ⅰ; the remaining steps, conditions and parameters are consistent with those in Preparation Example 3.

[0081] Preparation Examples 12 to 15 Based on Preparation Example 11, the difference between Preparation Examples 12 to 15 and Preparation Example 11 is that when the coating I with micron-sized doped diamond grains is subjected to hydrogen plasma etching, the parameters are different; the remaining steps, conditions and parameters are consistent with those in Preparation Example 11. Specifically, the parameters selected for Preparation Examples 12 to 15 are shown in Table 6.

[0082] Table 6 Summary of parameters of preparation examples 12 to 15 Preparation Example 12 Preparation Example 13 Preparation Example 14 Preparation Example 15 Hydrogen flow / SLM 7 7.5 8 10 Argon flow / SLM 4 3 3.5 2.5 Etching temperature / ℃ 880 850 950 1050 Etching pressure / kPa 3.6 3.2 4.0 4.5 Etching time / min 18 20 10 5 Preparation Example 16 Based on Preparation Example 6, the difference between this Preparation Example and Preparation Example 6 is that after the deposition of the coating layer I of micron-sized doped diamond grains is completed, the coating layer I of micron-sized doped diamond grains is further subjected to hydrogen plasma etching. The specific operation is as follows: After the deposition is completed, the introduction of methane and B is suspended in the CH4 / H2 deposition atmosphere to form a H2 plasma etching atmosphere: the hydrogen flow rate is 0.5SLM; the etching temperature is 800°C, the etching pressure is 3.8kPa, and the etching time is 30min; at this time, the surface of the coating Ⅰ of micron-sized doped diamond grains deposited on the surface of the silicon particles has micro-pits Ⅰ.

[0083] The remaining steps, conditions and parameters are consistent with those in Preparation Example 6.

[0084] Examples 11 to 16 Examples 11 to 16 respectively provide a diamond electrode prepared from silicon particles having a coating I with micron-sized doped diamond grains deposited on the surface and micro-pits I on the surface of the coating I with micron-sized doped diamond grains.

[0085] Based on Example 3, the difference between Examples 11 to 16 and Example 3 lies in the selection of conductive diamond particles 2, see Table 7; the remaining steps, conditions and parameters are consistent with those in Example 3.

[0086] Table 7 Selection of conductive diamond particles in Examples 11 to 16 Selected conductive diamond particles Embodiment 11 Preparation Example 11 Example 12 Preparation Example 12 Embodiment 13 Preparation Example 13 Embodiment 14 Preparation Example 14 Embodiment 15 Preparation Example 15 Example 16 Preparation Example 16 The electrode performance of the diamond electrodes provided in Examples 11 to 16 was tested, and the test results are recorded in Table 8.

[0087] Table 8 Summary of test results of Examples 11 to 16 Resistivity / mΩ·cm <![CDATA[Specific surface area / cm -1 > Aqueous solution potential window / V Embodiment 11 8.6 82.7 3.6 Example 12 8.7 82.1 3.6 Embodiment 13 8.6 84.7 3.6 Embodiment 14 8.6 81.6 3.6 Embodiment 15 8.6 80.5 3.6 Example 16 6.1 74.0 3.6 Referring to Table 8, it can be seen from the results of Table 8 that the resistivity and aqueous solution potential window of the diamond electrodes provided in Examples 11 to 15 are not significantly changed compared with the diamond electrodes provided in Example 3, and the diamond electrodes provided in Example 16 are not significantly changed compared with the diamond electrodes provided in Example 6. However, the specific surface area of ​​the diamond electrodes provided in Examples 11 to 15 is greatly increased compared with the diamond electrodes provided in Example 3, and the specific surface area of ​​the diamond electrodes provided in Example 16 is greatly increased compared with the diamond electrodes provided in Example 6. This shows that etching the coating I of micron-sized doped diamond grains deposited on the surface of the conductive diamond particles 2 can further increase the specific surface area of ​​the diamond electrode, and the comprehensive performance of the diamond electrode is better. Specifically, according to the test results of Examples 11 and 16, it can be seen that with the same etching time, the specific surface area of ​​the diamond electrode provided in Example 16 is smaller than the specific surface area of ​​the diamond electrode provided in Example 11, so the DC arc plasma jet chemical vapor deposition method has advantages.

[0088] Preparation Examples 17 to 26 Preparation Examples 17 to 26 respectively provide a heterogeneous material substrate particle having a coating I with nano-scale doped diamond grains deposited on the surface.

[0089] Preparation Example 17 Based on Preparation Example 1, the difference between this Preparation Example and Preparation Example 1 is that: in this Preparation Example, nanoscale doped diamond grain coating I is deposited on the surface of the heterogeneous material substrate particles. Compared with Preparation Example 1, different process parameters are used; specifically, the selected parameters are as follows: The hydrogen flow rate is 9 SLM, the argon flow rate is 2.5 SLM, and the methane flow rate is CH4 / H2=4%, forming a CH4 / H2 / Ar deposition atmosphere; a doping element B is introduced into the CH4 / H2 / Ar deposition atmosphere, the source of B is selected from borax, and the B doping amount is B / C=3000 ppm; the deposition temperature is 700° C., the deposition pressure is 2.5 kPa, and when the thickness of the deposited coating Ⅰ of nanoscale doped diamond grains is 8 μm, the deposition is stopped to obtain conductive diamond particles 2, wherein the conductive diamond particles 2 are silicon particles with a coating Ⅰ of nanoscale doped diamond grains deposited on the surface; The remaining steps, conditions and parameters are consistent with those in Preparation Example 1.

[0090] Preparation Examples 18 to 21 Based on Preparation Example 17, the difference between Preparation Examples 18 to 21 and Preparation Example 17 is that different parameters are used when depositing the coating layer I of nanoscale doped diamond grains; the remaining steps, conditions and parameters are consistent with those in Preparation Example 17. Specifically, the parameters selected for Preparation Examples 18 to 21 are shown in Table 9.

[0091] Table 9 Summary of parameters of preparation examples 18 to 21 Preparation Example 18 Preparation Example 19 Preparation Example 20 Preparation Example 21 Hydrogen flow / SLM 8.5 8 7.2 7 Argon flow / SLM 2.8 3 4 5 Methane flow / % <![CDATA[CH4 / H2=5]]> <![CDATA[CH4 / H2=6]]> <![CDATA[CH4 / H2=7]]> <![CDATA[CH4 / H2=8%]]> B doping amount / ppm B / C=5000 B / C=8000 B / C=10000 B / C=12000 Deposition temperature / ℃ 750 780 800 820 Deposition pressure / kPa 3.8 2.8 4.2 4.5 Preparation Example 22 Based on Preparation Example 17, the difference between this Preparation Example and Preparation Example 17 is that when depositing the coating I of nano-scale doped diamond grains, the chemical vapor deposition method selected in this Preparation Example is different, and the specific operation is as follows: The silicon particles with diamond seed crystals pre-placed on the surface are placed in a microwave plasma chemical vapor deposition chamber to deposit a coating I of nano-scale doped diamond grains; specifically, the parameters selected are as follows: The hydrogen flow rate is 0.1 SLM, the argon flow rate is 0.3 SLM, and the methane flow rate is CH4 / H2=4%, forming a CH4 / H2 / Ar deposition atmosphere; a doping element B is introduced into the CH4 / H2 / Ar deposition atmosphere, the source of B is selected from borax, and the B doping amount is B / C=7800 ppm; the deposition temperature is 720°C, the deposition pressure is 4.0 kPa, and when the thickness of the deposited coating Ⅰ of nanoscale doped diamond grains is 8 μm, the deposition is stopped to obtain conductive diamond particles 2, wherein the conductive diamond particles 2 are silicon particles with a coating Ⅰ of nanoscale doped diamond grains deposited on the surface; The remaining steps, conditions and parameters are consistent with those in Preparation Example 17.

[0092] Examples 17 to 26 Examples 17 to 26 respectively provide a diamond electrode made from silicon particles having a coating I with nano-scale doped diamond grains deposited on the surface.

[0093] Examples 17 to 22 Based on Example 1, the difference between Examples 17 to 22 and Example 1 lies in the selection of conductive diamond particles 2, see Table 10; the remaining steps, conditions and parameters are consistent with those in Example 1.

[0094] Table 10 Selection of conductive diamond particles in Examples 17 to 22 Selected conductive diamond particles Embodiment 17 Preparation Example 17 Embodiment 18 Preparation Example 18 Embodiment 19 Preparation Example 19 Embodiment 20 Preparation Example 20 Embodiment 21 Preparation Example 21 Embodiment 22 Preparation Example 22 The electrode performance of the diamond electrodes provided in Examples 17 to 22 was tested, and the test results are recorded in Table 11.

[0095] Table 11 Summary of test results of Examples 17 to 22 As shown in Table 11, the specific surface area of ​​the diamond electrodes provided in Examples 17 to 22 is 37.5 cm -1As for the resistivity, the resistivity of Example 17 is larger than that of Examples 18 to 22. The reason is that the resistivity is mainly determined by the amount of boron doping. When the amount of boron doping is low, the influence on the resistivity of the diamond electrode is greater. When the amount of boron doping reaches a certain value, the amount of boron doping is basically saturated. At this time, the influence on the resistivity of the diamond electrode is small. Therefore, as the amount of boron doping increases, the rate of change of resistivity is greatly reduced. However, according to the results of Table 11, the diamond electrodes provided by Examples 17 to 22 still have good comprehensive performance.

[0096] Specifically, although the comprehensive performance of the diamond electrode provided in Example 22 is also good, the conductive diamond particles 2 used in the diamond electrode provided in Example 22 are conductive diamond particles 2 deposited by microwave plasma chemical vapor deposition. Compared with the conductive diamond particles 2 deposited by DC arc plasma jet chemical vapor deposition in the diamond electrodes provided in Examples 17 to 21, the growth rate of the coating Ⅰ of the nano-scale doped diamond grains is slower, so the DC arc plasma jet chemical vapor deposition method is superior; in addition, in Examples 17 to 21, the comprehensive performance of the diamond electrode provided in Example 19 is better, that is, the performance of the diamond electrode prepared using the conductive diamond particles 2 prepared in Preparation Example 19 is better.

[0097] Preparation Examples 23 to 26 Based on Preparation Example 19, the difference between Preparation Examples 23 to 26 and Preparation Example 19 is that the thickness of the coating I of the nanoscale doped diamond grains deposited in Preparation Examples 23 to 26 is different. In Preparation Examples 23 to 26, the deposition is stopped when the thickness of the deposited coating I of the nanoscale doped diamond grains is 2 μm, 4 μm, 6 μm and 10 μm, respectively; the remaining steps, conditions and parameters are the same as those in Preparation Example 19.

[0098] Embodiments 23 to 26 Based on Example 19, the difference between Examples 23 to 26 and Example 19 lies in the selection of conductive diamond particles 2, see Table 12; the remaining steps, conditions and parameters are consistent with those in Example 19.

[0099] Table 12 Selection of conductive diamond particles in Examples 23 to 26 Selected conductive diamond particles Embodiment 23 Preparation Example 23 Embodiment 24 Preparation Example 24 Embodiment 25 Preparation Example 25 Embodiment 26 Preparation Example 26 The electrode performance of the diamond electrodes provided in Examples 23 to 26 was tested, and the test results are recorded in Table 13.

[0100] Table 13 Summary of test results of Examples 23 to 26 Resistivity / mΩ·cm <![CDATA[Specific surface area / cm -1 > Aqueous solution potential window / V Embodiment 23 2.9 38.7 3.2 Embodiment 24 2.7 38.9 3.2 Embodiment 25 2.7 39.2 3.2 Embodiment 26 2.6 39.6 3.2 Referring to Table 13, it can be seen from the results of Table 13 that when using heterogeneous material substrate particles with the same average particle size, the specific surface area of ​​the diamond electrode increases slightly with the increase in the thickness of the coating I of nanoscale doped diamond grains deposited on the surface of the heterogeneous material substrate particles, but the increase gradually decreases. By comparing the test results of Example 19 and Examples 23 to 26, it can be seen that the diamond electrodes provided by Examples 19 and 26 have the largest specific surface area, the lowest resistivity, and the aqueous solution potential window is not reduced, and the electrode has better comprehensive performance, but the coating I of nanoscale doped diamond grains deposited on the surface of the conductive diamond particles 2 prepared in Preparation Example 26 is thicker and the deposition time is longer, so the diamond electrode prepared using the conductive diamond particles 2 prepared in Preparation Example 19 is more superior.

[0101] Preparation Examples 27 to 30 Preparation Examples 27 to 30 respectively provide a heterogeneous material substrate particle having a coating I with nano-scale doped diamond grains deposited on the surface, and the coating I with nano-scale doped diamond grains is a porous structure I.

[0102] Preparation Example 27 Based on Preparation Example 19, the difference between this Preparation Example and Preparation Example 19 is that it also includes alternating deposition and hydrogen plasma etching of the coating layer I of the nanoscale doped diamond grains during the deposition process, and the specific operations are as follows: After 5 minutes of deposition, the introduction of methane and the introduction of B were suspended in the CH4 / H2 / Ar deposition atmosphere to form a H2 / Ar etching atmosphere, and hydrogen plasma etching was performed for 1.25 minutes; after the etching was completed, methane was introduced into the H2 / Ar etching atmosphere and B was introduced, and the deposition was continued for 5 minutes, and hydrogen plasma etching for 1.25 minutes and deposition for 5 minutes were performed alternately, and when the thickness of the deposited coating I of nanoscale doped diamond grains was 8 μm, the deposition was stopped to obtain conductive diamond particles 2; at this time, the conductive diamond particles 2 were silicon particles with a coating I of nanoscale doped diamond grains deposited on the surface, and the coating I of the nanoscale doped diamond grains was a porous structure I; The remaining steps, conditions and parameters are consistent with those in Preparation Example 19.

[0103] Preparation Example 28 Based on Preparation Example 27, the difference between this Preparation Example and Preparation Example 27 is that after deposition for 10 minutes, hydrogen plasma etching is performed for 3.3 minutes, and then deposition for 10 minutes and hydrogen plasma etching for 3.3 minutes are performed alternately. When the thickness of the deposited nanoscale doped diamond grain coating Ⅰ is 8 μm, deposition is stopped; the remaining steps, conditions and parameters are consistent with those in Preparation Example 27.

[0104] Preparation Example 29 Based on Preparation Example 27, the difference between this Preparation Example and Preparation Example 27 is that after deposition for 15 minutes, hydrogen plasma etching is performed for 5 minutes, and then deposition for 15 minutes and hydrogen plasma etching for 5 minutes are performed alternately. When the thickness of the deposited nanoscale doped diamond grain coating I is 8 μm, deposition is stopped; the remaining steps, conditions and parameters are consistent with those in Preparation Example 27.

[0105] Preparation Example 30 Based on Preparation Example 22, the difference between this Preparation Example and Preparation Example 22 is that in this Preparation Example, the coating I of the nanoscale doped diamond grains during the deposition process is subjected to alternate deposition and hydrogen-argon plasma etching, and the specific operation is as follows: After 15 minutes of deposition, the introduction of methane and the introduction of B were suspended in the CH4 / H2 / Ar deposition atmosphere to form a H2 / Ar etching atmosphere, and hydrogen plasma etching was performed for 5 minutes; after the etching was completed, methane was introduced into the H2 / Ar etching atmosphere and B was introduced, and the deposition was continued for 15 minutes, and hydrogen plasma etching for 5 minutes and deposition for 15 minutes were performed alternately, and when the thickness of the deposited coating I of nanoscale doped diamond grains was 8 μm, the deposition was stopped to obtain conductive diamond particles 2; at this time, the conductive diamond particles 2 were silicon particles with a coating I of nanoscale doped diamond grains deposited on the surface, and the coating I of the nanoscale doped diamond grains was a porous structure I; The remaining steps, conditions and parameters are consistent with those in Preparation Example 22.

[0106] Examples 27 to 30 Examples 27 to 30 respectively provide a diamond electrode prepared from silicon particles having a porous structure I and a coating I with nano-scale doped diamond grains deposited on the surface.

[0107] Based on Example 1, the difference between Examples 27 to 30 and Example 1 lies in the selection of conductive diamond particles 2, see Table 14; the remaining steps, conditions and parameters are consistent with those in Example 1.

[0108] Table 14 Selection of conductive diamond particles in Examples 27 to 30 Selected conductive diamond particles Embodiment 27 Preparation Example 27 Embodiment 28 Preparation Example 28 Embodiment 29 Preparation Example 29 Embodiment 30 Preparation Example 30 The electrode performance of the diamond electrodes provided in Examples 27 to 30 was tested, and the test results are recorded in Table 15.

[0109] Table 15 Summary of test results of Examples 27 to 30 Referring to Table 15, it can be seen from the results in Table 15 that the resistivity of the diamond electrodes provided in Examples 27 to 29 is slightly increased compared with that provided in Example 19, and that of Example 30 is slightly increased compared with that provided in Example 22, and the aqueous solution potential window has no obvious change. However, the specific surface area of ​​the diamond electrodes provided in Examples 27 to 29 is significantly increased compared with that provided in Example 19, and the specific surface area of ​​the diamond electrode provided in Example 30 is significantly increased compared with that provided in Example 22, and the specific surface area of ​​the diamond electrodes provided in Examples 27 to 30 is all above 5800 cm -1 This shows that the specific surface area of ​​the diamond electrode can be further increased and the overall performance of the diamond electrode is better after the coating I of the nano-scale doped diamond grains deposited on the surface of the conductive diamond particles 2 is subjected to alternate deposition and hydrogen plasma etching.

[0110] Specifically, although the diamond electrode provided in Example 30 has better comprehensive performance, the conductive diamond particles 2 used in the diamond electrode provided in Example 30 are conductive diamond particles 2 obtained by microwave plasma chemical vapor deposition and hydrogen plasma etching. Compared with the conductive diamond particles 2 deposited by DC arc plasma jet chemical vapor deposition in the diamond electrodes provided in Examples 27 to 29, the coating Ⅰ of nano-scale doped diamond grains with porous structure Ⅰ grows slower, so the DC arc plasma jet chemical vapor deposition method is superior.

[0111] Preparation Examples 31 to 34 Preparation Examples 31 to 34 respectively provide a heterogeneous material substrate particle with a first coating and a second coating deposited on the surface; wherein the first coating is a coating II of micron-scale doped diamond grains and has micro-pits II on the surface, and the second coating is a coating II of nano-scale doped diamond grains and has a porous structure II, and the second coating is deposited on the first coating.

[0112] Preparation Example 31 Based on Preparation Example 1, the difference between this Preparation Example and Preparation Example 1 is that: this Preparation Example deposits the first coating and the second coating on the surface of the heterogeneous material substrate particles. Compared with Preparation Example 1, the following operations are different: silicon particles with diamond seed crystals pre-placed on the surface are placed in a DC arc plasma jet chemical vapor deposition chamber to deposit the first coating and the second coating, including the following steps: A1, the hydrogen flow rate is 10SLM, the argon flow rate is 2.5SLM, and the methane flow rate is CH4 / H2=1%, forming a CH4 / H2 / Ar deposition atmosphere; introducing a doping element B in the CH4 / H2 / Ar deposition atmosphere, the source of B is selected from trimethyl borate, and the B doping amount is B / C=3000ppm; the deposition temperature is 780°C, the deposition pressure is 2.5kPa, until the thickness of the deposited micron-sized doped diamond grain coating Ⅰ is 10μm; A2, suspend the introduction of methane and B to form a H2 / Ar etching atmosphere: the hydrogen flow rate is 6SLM, the argon flow rate is 5SLM; the etching temperature is 750℃, the etching pressure is 2.8kPa, and the etching time is 30min; A3, continue to introduce methane and introduce B to form a CH4 / H2 / Ar deposition atmosphere: the hydrogen flow rate is 9SLM, the argon flow rate is 2.5SLM, and the methane flow rate is CH4 / H2=4%; introduce the doping element B in the CH4 / H2 / Ar deposition atmosphere, and the B doping amount is B / C=3000ppm; the deposition temperature is 700℃, the deposition pressure is 2.5kPa, and the deposition is 5min; A4, suspend the introduction of methane and B, form a H2 / Ar etching atmosphere, and perform hydrogen plasma etching for 1.25 min; Return to step A3, until the thickness of the deposited coating layer I of the nanoscale doped diamond grains of the porous structure I is 8 μm, and then stop the deposition and hydrogen plasma etching; The remaining steps, conditions and parameters are consistent with those in Preparation Example 1.

[0113] Preparation Examples 32-33 Based on Preparation Example 31, the difference between Preparation Examples 32 to 33 and Preparation Example 31 is that the parameters are different when depositing the first coating and the second coating, and the remaining steps, conditions and parameters are consistent with those in Preparation Example 31; specifically, the parameters selected for Preparation Examples 32 to 33 are shown in Table 16.

[0114] Table 16 Summary of parameters of preparation examples 32 to 33 Preparation Example 34 Based on Preparation Example 1, the difference between this Preparation Example and Preparation Example 1 is that when depositing the first coating layer and the second coating layer, the chemical vapor deposition method selected in this Preparation Example is different, and the specific operation is as follows: Placing silicon particles with diamond seed crystals pre-placed on the surface in a microwave plasma chemical vapor deposition chamber to deposit a first coating and a second coating, comprising the following steps: B1, the hydrogen flow rate is 0.5SLM, the methane flow rate is CH4 / H2=1.5%, forming a CH4 / H2 deposition atmosphere; introducing the doping element B in the CH4 / H2 deposition atmosphere, the source of B is selected from trimethyl borate, and the B doping amount is B / C=8000ppm; the deposition temperature is 800°C, the deposition pressure is 4kPa, until the thickness of the deposited micron-sized doped diamond grain coating I is 10μm; B2, suspend the introduction of methane and B to form H2 plasma etching atmosphere: hydrogen flow rate is 0.5SLM; etching temperature is 800℃, etching pressure is 3.8kPa, and etching time is 30min; B3, continue to introduce methane and introduce B to form a CH4 / H2 / Ar deposition atmosphere: the hydrogen flow rate is 0.1SLM, the argon flow rate is 0.3SLM, the methane flow rate is CH4 / H2=4%, forming a CH4 / H2 / Ar deposition atmosphere; introduce the doping element B into the CH4 / H2 / Ar deposition atmosphere, and the B doping amount is B / C=7800ppm; the deposition temperature is 720°C, the deposition pressure is 4kPa, and the deposition is 15min; B4, suspend the introduction of methane and B, form a H2 / Ar etching atmosphere, and perform hydrogen plasma etching for 5 minutes; Return to step B3, until the thickness of the deposited coating I of nanoscale doped diamond grains of porous structure I is 8 μm, and then stop the deposition and hydrogen plasma etching; The remaining steps, conditions and parameters are consistent with those in Preparation Example 1.

[0115] Examples 31 to 34 Examples 31 to 34 respectively provide a diamond electrode prepared using the above-mentioned silicon particles with the first coating and the second coating deposited on the surface.

[0116] Based on Example 1, the difference between Examples 31 to 34 and Example 1 lies in the selection of conductive diamond particles 2, see Table 17; the remaining steps, conditions and parameters are consistent with those in Example 1.

[0117] Table 17 Selection of conductive diamond particles in Examples 31 to 34 Selected conductive diamond particles Embodiment 31 Preparation Example 31 Embodiment 32 Preparation Example 32 Embodiment 33 Preparation Example 33 Embodiment 34 Preparation Example 34 The electrode performance of the diamond electrodes provided in Examples 31 to 34 was tested, and the test results are recorded in Table 18.

[0118] Table 18 Summary of test results of Examples 31 to 34 Resistivity / mΩ·cm <![CDATA[Specific surface area / cm -1 > Aqueous solution potential window / V Embodiment 31 45.4 7052.2 3.2 Embodiment 32 6.8 8530.6 3.3 Embodiment 33 5.7 6180.0 3.2 Embodiment 34 7.6 7370.5 3.3 Referring to Table 18, it can be seen from the results of Table 18 that the diamond electrodes provided by Examples 31 to 34 have a larger specific surface area than the diamond electrodes provided by Examples 1 to 30, and the aqueous solution potential window is also between 3.2 and 3.3 V; for resistivity, Example 31 has a larger resistivity than Examples 32 to 34, because the resistivity is mainly determined by the amount of boron doping. When the amount of boron doping is low, the influence on the resistivity of the diamond electrode is greater. When the amount of boron doping reaches a certain value, the amount of boron doping is basically saturated. At this time, the influence on the resistivity of the diamond electrode is small, so as the amount of boron doping increases, the rate of change of resistivity is greatly reduced. However, according to the results of Table 18, it can be seen that the diamond electrodes provided by Examples 31 to 34 still have good comprehensive performance.

[0119] Specifically, although the comprehensive performance of the diamond electrode provided in Example 34 is also good, the conductive diamond particles 2 used in the diamond electrode provided in Example 34 are conductive diamond particles 2 deposited by microwave plasma chemical vapor deposition. Compared with the conductive diamond particles 2 deposited by DC arc plasma jet chemical vapor deposition in the diamond electrodes provided in Examples 31 to 33, the growth rate of the doped diamond coating is slower, so the DC arc plasma jet chemical vapor deposition method is superior.

[0120] Electron microscope detection The surfaces of the silicon particles with doped diamond coatings deposited on the surfaces provided in Preparation Examples 1 to 34 were observed using an electron microscope to detect the grain density and grain distribution of the doped diamond coatings on the surfaces.

[0121] This application lists the electron micrographs of some preparation examples, and the electron micrographs corresponding to Preparation Example 3 are shown in FIG. Figure 2 As shown, the electron microscope image corresponding to Preparation Example 13 is as follows Figure 3 As shown, the electron microscope image corresponding to Preparation Example 19 is as follows Figure 4 As shown, the electron microscope image corresponding to Preparation Example 28 is as follows Figure 5 As shown, the electron microscope image corresponding to Preparation Example 32 is as follows Figure 6 shown.

[0122] According to the results of electron microscopy, Figure 2 to Figure 6 In the doped diamond coating shown, the doped diamond grains have no obvious defect points, and the distribution of the doped diamond grains is relatively uniform, and the particle size uniformity of the doped diamond grains is relatively good.

[0123] Specifically, compared with the electron microscope image corresponding to Preparation Example 13, the electron microscope image corresponding to Preparation Example 3 shows that the surface of the coating I of the micron-scale doped diamond grains corresponding to Preparation Example 13 is relatively rough, and there are a large number of micro-pits; compared with the electron microscope image corresponding to Preparation Example 19, the electron microscope image corresponding to Preparation Example 28 shows that the coating I of the nano-scale doped diamond grains corresponding to Preparation Example 28 has a higher porosity, forming a porous structure I.

[0124] In order to further verify the feasibility of preparing diamond electrodes after preparing conductive diamond particles 2 using heterogeneous material substrate particles of other materials, the present application also provides preparation examples 35 to 40 and embodiments 35 to 40.

[0125] Preparation Examples 35 to 37 Preparation Examples 35 to 37 respectively provide a conductive diamond particle 2 prepared from heterogeneous material substrate particles of silicon carbide.

[0126] Preparation Example 35 Taking Preparation Example 13 as an example, the difference between this Preparation Example and Preparation Example 13 is that the material of the heterogeneous material substrate particles selected in this Preparation Example is different, and silicon carbide blocks are selected to replace silicon blocks in this Preparation Example; the remaining steps, conditions and parameters are consistent with Preparation Example 13.

[0127] Preparation Example 36 Taking Preparation Example 28 as an example, the difference between this Preparation Example and Preparation Example 28 is that the material of the heterogeneous material substrate particles selected in this Preparation Example is different, and silicon carbide blocks are selected to replace silicon blocks in this Preparation Example; the remaining steps, conditions and parameters are consistent with Preparation Example 28.

[0128] Preparation Example 37 Taking Preparation Example 32 as an example, the difference between this Preparation Example and Preparation Example 32 is that the material of the heterogeneous material substrate particles selected in this Preparation Example is different, and silicon carbide blocks are selected to replace silicon blocks in this Preparation Example; the remaining steps, conditions and parameters are consistent with Preparation Example 32.

[0129] Preparation Examples 38 to 40 Preparation Examples 38 to 40 respectively provide a conductive diamond particle 2 prepared from heterogeneous material substrate particles of silicon nitride.

[0130] Preparation Example 38 Taking Preparation Example 13 as an example, the difference between this Preparation Example and Preparation Example 13 is that the material of the heterogeneous material substrate particles selected in this Preparation Example is different, and silicon nitride blocks are selected to replace silicon blocks in this Preparation Example; the remaining steps, conditions and parameters are consistent with Preparation Example 13.

[0131] Preparation Example 39 Taking Preparation Example 28 as an example, the difference between this Preparation Example and Preparation Example 28 is that the material of the heterogeneous material substrate particles selected in this Preparation Example is different, and silicon nitride blocks are selected to replace silicon blocks in this Preparation Example; the remaining steps, conditions and parameters are consistent with Preparation Example 28.

[0132] Preparation Example 40 Taking Preparation Example 32 as an example, the difference between this Preparation Example and Preparation Example 32 is that the material of the heterogeneous material substrate particles selected in this Preparation Example is different, and silicon nitride blocks are selected to replace silicon blocks in this Preparation Example; the remaining steps, conditions and parameters are consistent with Preparation Example 32.

[0133] Embodiments 35 to 40 Based on Example 1, the difference between Examples 35 to 40 and Example 1 lies in the selection of conductive diamond particles 2, see Table 19; the remaining steps, conditions and parameters are consistent with those in Example 1.

[0134] Table 19 Selection of conductive diamond particles in Examples 35 to 40 Selected conductive diamond particles Embodiment 35 Preparation Example 35 Embodiment 36 Preparation Example 36 Embodiment 37 Preparation Example 37 Embodiment 38 Preparation Example 38 Embodiment 39 Preparation Example 39 Embodiment 40 Preparation Example 40 The electrode performance of the diamond electrodes provided in Examples 35 to 40 was tested, and the test results are recorded in Table 20.

[0135] Table 20 Summary of test results of Examples 35 to 40 Resistivity / mΩ·cm <![CDATA[Specific surface area / cm -1 > Aqueous solution potential window / V Embodiment 35 8.9 86.3 3.6 Embodiment 36 7.3 6348.6 3.3 Embodiment 37 6.9 8472.7 3.3 Embodiment 38 8.1 84.8 3.5 Embodiment 39 6.5 6206.3 3.3 Embodiment 40 6.5 8572.9 3.3 Referring to Table 20, it can be seen from the results in Table 20 that the comprehensive performance of the diamond electrodes provided by Examples 35 to 40 is good, which illustrates the feasibility of selecting other materials for the heterogeneous material substrate particles.

[0136] In order to further verify the feasibility of using other diamond powder suspensions to pre-place diamond seed crystals, the present application also provides Preparation Examples 41 to 43 and Examples 41 to 43.

[0137] Preparation Example 41 Based on Preparation Example 32, the difference between this Preparation Example and Preparation Example 32 is that the diamond powder suspension selected in this Preparation Example is different: in the diamond powder suspension, the mass fraction of diamond powder with a particle size of 3 μm is 40%, and the mass fraction of diamond powder with a particle size of 35 μm is 60%, and the solvent is anhydrous ethanol; the remaining steps, conditions and parameters are consistent with those in Preparation Example 32.

[0138] Preparation Example 42 Based on Preparation Example 37, the difference between this Preparation Example and Preparation Example 37 is that the diamond powder suspension selected in this Preparation Example is different: in the diamond powder suspension, the mass fraction of diamond powder with a particle size of 4 μm is 60%, and the mass fraction of diamond powder with a particle size of 45 μm is 40%, and the solvent is anhydrous ethanol; the remaining steps, conditions and parameters are consistent with those in Preparation Example 37.

[0139] Preparation Example 43 Based on Preparation Example 40, the difference between this Preparation Example and Preparation Example 40 is that the diamond powder suspension selected in this Preparation Example is different: in the diamond powder suspension, the mass fraction of diamond powder with a particle size of 5 μm is 40%, and the mass fraction of diamond powder with a particle size of 35 μm is 60%, and the solvent is anhydrous ethanol; the remaining steps, conditions and parameters are the same as those in Preparation Example 40.

[0140] Embodiments 41 to 43 Based on Example 1, the difference between Examples 41 to 43 and Example 1 lies in the selection of conductive diamond particles 2, see Table 21; the remaining steps, conditions and parameters are consistent with those in Example 1.

[0141] Table 21 Selection of conductive diamond particles in Examples 41 to 43 Selected conductive diamond particles Embodiment 41 Preparation Example 41 Embodiment 42 Preparation Example 42 Embodiment 43 Preparation Example 43 The electrode performance of the diamond electrodes provided in Examples 41 to 43 was tested and the test results are recorded in Table 22.

[0142] Table 22 Summary of test results of Examples 41 to 43 Resistivity / mΩ·cm <![CDATA[Specific surface area / cm -1 > Aqueous solution potential window / V Embodiment 41 6.8 8508.5 3.3 Embodiment 42 6.9 8458.3 3.3 Embodiment 43 6.6 8521.9 3.3 Referring to Table 22, it can be seen from the results in Table 22 that the comprehensive performance of the diamond electrodes provided by Examples 41 to 43 is good, and the test results of Example 41 are compared with Example 32, the test results of Example 42 are compared with Example 37, and the test results of Example 43 are compared with Example 40. The resistivity, specific surface area and aqueous solution potential window are not much different, which illustrates the feasibility of selecting other diamond powder suspensions for pre-setting diamond seed crystals.

[0143] In order to further verify the feasibility of preparing diamond electrodes by using heterogeneous material substrate particles with different doped diamond coatings deposited on the surface, the present application also provides Examples 44 to 49.

[0144] Embodiments 44 to 49 Based on Example 1, the difference between Examples 44 to 49 and Example 1 lies in the selection of conductive diamond particles 2, see Table 23; wherein, in the diamond electrodes provided by Examples 44 to 49, the number of conductive diamond particles 2 provided by different preparation examples is the same; the remaining steps, conditions and parameters are consistent with those in Example 1.

[0145] Table 23 Selection of conductive diamond particles in Examples 44 to 49 Selected conductive diamond particles Embodiment 44 Preparation Example 3, Preparation Example 13 Embodiment 45 Preparation Example 13, Preparation Example 19 Embodiment 46 Preparation Example 19, Preparation Example 28 Embodiment 47 Preparation Example 3, Preparation Example 13, Preparation Example 32 Embodiment 48 Preparation Example 19, Preparation Example 28, Preparation Example 32 Embodiment 49 Preparation Example 3, Preparation Example 13, Preparation Example 19, Preparation Example 28, Preparation Example 32 The electrode performance of the diamond electrodes provided in Examples 44 to 49 was tested and the test results are recorded in Table 24.

[0146] Table 24 Summary of test results of Examples 44 to 49 <![CDATA[Specific surface area / cm -1 > Aqueous solution potential window / V Embodiment 44 67.9 3.6 Embodiment 45 63.4 3.3 Embodiment 46 3108.9 3.2 Embodiment 47 2866.8 3.3 Embodiment 48 4932.7 3.2 Embodiment 49 2987.6 3.2 Referring to Table 24, it can be seen from the results in Table 24 that the comprehensive performance of the diamond electrodes provided by Examples 44 to 49 can also reach a good level, which illustrates the feasibility of selecting heterogeneous material substrate particles deposited with different doped diamond coatings.

[0147] It should be noted that the resistivity of the diamond electrodes provided in Examples 44 to 49 was not measured. The reason is that in the diamond electrodes provided in Examples 44 to 49, the doped diamond coating deposited on the surface of the heterogeneous material substrate particles plays a conductive role. Therefore, when the resistivity of the diamond electrode is measured, it is measured by a four-point probe method, and the film resistance of the doped diamond coating is measured. After the conductive diamond particles 2 provided in different preparation examples are mixed, the film resistance on the surface of each conductive diamond particle 2 remains unchanged. In addition, Table 23 does not limit the selection and combination of the conductive diamond particles 2, that is, any two or more heterogeneous material substrate particles with doped diamond coatings deposited on the surface in Preparation Examples 1 to 43 can be selected and combined arbitrarily to prepare the diamond electrode.

[0148] In order to further verify the feasibility of preparing diamond electrodes by doping diamond coating with diamond substrate particles made of diamond material in addition to heterogeneous material substrate particles, the present application also provides preparation examples 44 to 48 and embodiments 50 to 54.

[0149] Preparation Example 44 Based on Preparation Example 3, the difference between this Preparation Example and Preparation Example 3 is that: this Preparation Example uses diamond substrate particles to replace the heterogeneous material substrate particles, and omits the step of pre-setting diamond seed crystals; the remaining steps, conditions and parameters are consistent with those in Preparation Example 3, and diamond substrate particles with coating Ⅰ deposited with micron-sized doped diamond grains on the surface are obtained.

[0150] Preparation Example 45 Based on Preparation Example 13, the difference between this Preparation Example and Preparation Example 13 is that: this Preparation Example uses diamond substrate particles to replace the heterogeneous material substrate particles, and omits the step of pre-setting diamond seed crystals; the remaining steps, conditions and parameters are consistent with those in Preparation Example 13, and diamond substrate particles are obtained, the surface of which is deposited with coating Ⅰ of micron-sized doped diamond grains, and the surface of coating Ⅰ of micron-sized doped diamond grains has micro-pits Ⅰ.

[0151] Preparation Example 46 Based on Preparation Example 19, the difference between this Preparation Example and Preparation Example 19 is that: this Preparation Example uses diamond substrate particles to replace the heterogeneous material substrate particles, and omits the step of pre-setting diamond seed crystals; the remaining steps, conditions and parameters are consistent with those in Preparation Example 19, and diamond substrate particles with coating Ⅰ deposited with nano-scale doped diamond grains on the surface are obtained.

[0152] Preparation Example 47 Based on Preparation Example 28, the difference between this Preparation Example and Preparation Example 28 is that: this Preparation Example uses diamond substrate particles to replace the heterogeneous material substrate particles, and omits the step of pre-setting diamond seed crystals; the remaining steps, conditions and parameters are consistent with those in Preparation Example 28, and diamond substrate particles with a coating I deposited on the surface with nano-scale doped diamond grains, and the coating I of the nano-scale doped diamond grains is a porous structure I are obtained.

[0153] Preparation Example 48 Based on Preparation Example 32, the difference between this Preparation Example and Preparation Example 32 is that: this Preparation Example uses diamond substrate particles to replace the heterogeneous material substrate particles, and omits the step of pre-setting diamond seed crystals; the remaining steps, conditions and parameters are consistent with those in Preparation Example 32, and diamond substrate particles with a first coating and a second coating deposited on the surface are obtained.

[0154] Embodiments 50 to 54 Examples 50 to 54 respectively provide a diamond electrode prepared using the above-mentioned diamond substrate particles with a doped diamond coating deposited on the surface.

[0155] Based on Example 1, the difference between Examples 50 to 54 and Example 1 lies in the selection of conductive diamond particles 2, see Table 25; the remaining steps, conditions and parameters are consistent with those in Example 1.

[0156] Table 25 Selection of conductive diamond particles in Examples 50 to 54 Selected conductive diamond particles Embodiment 50 Preparation Example 44 Embodiment 51 Preparation Example 45 Embodiment 52 Preparation Example 46 Embodiment 53 Preparation Example 47 Embodiment 54 Preparation Example 48 The electrode performance of the diamond electrodes provided in Examples 50 to 54 was tested and the test results are recorded in Table 26.

[0157] Table 26 Summary of test results of Examples 50 to 54 Resistivity / mΩ·cm <![CDATA[Specific surface area / cm -1 > Aqueous solution potential window / V Embodiment 50 8.7 49.7 3.6 Embodiment 51 8.7 82.9 3.6 Embodiment 52 3.1 37.4 3.3 Embodiment 53 7.1 5987.9 3.4 Embodiment 54 7.2 8023.6 3.4 Referring to Table 26, it can be seen from the results in Table 26 that the comprehensive performance of the diamond electrodes provided by Examples 50 to 54 is good, and the test results of Example 50 are compared with Example 3, the test results of Example 51 are compared with Example 13, the test results of Example 52 are compared with Example 19, the test results of Example 53 are compared with Example 28, and the test results of Example 54 are compared with Example 32. The resistivity, specific surface area and aqueous solution potential window are not much different, which illustrates the feasibility of preparing diamond electrodes after selecting diamond substrate particles for deposition of doped diamond coating.

[0158] In order to further verify the feasibility of using doped diamond particles in addition to heterogeneous material substrate particles and diamond substrate particles to prepare diamond electrodes, the present application also provides Preparation Examples 49 to 51 and Examples 55 to 57.

[0159] Preparation Example 49 The method of synthesizing doped diamond particles by high temperature and high pressure includes the following steps: Graphite is used as a carbon source and high-purity boron powder is used as a source of doping element B. Under the condition that the mass ratio between boron element and carbon element is controlled to be 4%, graphite and boron powder are evenly mixed; under the condition that Fe-Ni is used as a catalyst, the reaction temperature is controlled to be 1300°C and the reaction pressure is controlled to be 4.5GPa. The reaction time is 9 minutes to obtain octahedral doped diamond particles, and the above doped diamond particles are sieved to select doped diamond particles with an average particle size of 0.5mm.

[0160] Preparation Example 50 The method of synthesizing doped diamond particles by high temperature and high pressure includes the following steps: Graphite is used as a carbon source and high-purity boron powder is used as a source of doping element B. Under the condition that the mass ratio between boron element and carbon element is controlled to be 10%, graphite and boron powder are evenly mixed; under the condition that Fe-Ni is used as a catalyst, the reaction temperature is controlled to be 1500°C and the reaction pressure is controlled to be 7GPa. The reaction is carried out for 5 minutes to obtain octahedral doped diamond particles, and the above doped diamond particles are screened to select doped diamond particles with an average particle size of 0.5 mm.

[0161] Preparation Example 51 The method of synthesizing doped diamond particles by high temperature and high pressure includes the following steps: Graphite is used as a carbon source and high-purity boron powder is used as a source of doping element B. Under the condition that the mass ratio between boron element and carbon element is controlled to be 20%, graphite and boron powder are evenly mixed; under the condition that Fe-Ni is used as a catalyst, the reaction temperature is controlled to be 1800°C and the reaction pressure is 10GPa. The reaction time is 4 minutes to obtain octahedral doped diamond particles, and the above doped diamond particles are sieved to select doped diamond particles with an average particle size of 0.5 mm.

[0162] Embodiments 55 to 57 Examples 55 to 57 respectively provide a diamond electrode prepared using the above-mentioned doped diamond particles.

[0163] Based on Example 1, the difference between Examples 55 to 57 and Example 1 lies in the selection of conductive diamond particles 2, see Table 27; the remaining steps, conditions and parameters are consistent with those in Example 1.

[0164] Table 27 Selection of conductive diamond particles in Examples 55 to 57 Selected conductive diamond particles Embodiment 55 Preparation Example 49 Embodiment 56 Preparation Example 50 Embodiment 57 Preparation Example 51 The electrode performance of the diamond electrodes provided in Examples 55 to 57 was tested and the test results are recorded in Table 28.

[0165] Table 28 Summary of test results of Examples 55 to 57 Resistivity / mΩ·cm <![CDATA[Specific surface area / cm -1 > Aqueous solution potential window / V Embodiment 55 97.4 31.2 3.6 Embodiment 56 23.8 33.0 3.6 Embodiment 57 6.4 32.7 3.5 Referring to Table 28, it can be seen from the results in Table 28 that the comprehensive performance of the diamond electrodes provided by Examples 55 to 57 is good, which illustrates the feasibility of selecting doped diamond particles to prepare diamond electrodes.

[0166] In order to further verify the feasibility of preparing diamond electrodes using conductive diamond particles 2 of different particle types, the present application also provides Examples 58 to 63.

[0167] Examples 58 to 63 Based on Example 1, the difference between Examples 58 to 63 and Example 1 lies in the selection of conductive diamond particles 2, see Table 29; wherein, in the diamond electrodes provided in Examples 58 to 63, the number of conductive diamond particles 2 provided by different preparation examples is the same; the remaining steps, conditions and parameters are consistent with those in Example 1.

[0168] Table 29 Selection of conductive diamond particles in Examples 58 to 63 Selected conductive diamond particles Embodiment 58 Preparation Example 28, Preparation Example 47 Embodiment 59 Preparation Example 32, Preparation Example 49 Embodiment 60 Preparation Example 48, Preparation Example 49 Embodiment 61 Preparation Example 3, Preparation Example 44, Preparation Example 49 Embodiment 62 Preparation Example 13, Preparation Example 45, Preparation Example 50 Embodiment 63 Preparation Example 19, Preparation Example 46, Preparation Example 51 The electrode performance of the diamond electrodes provided in Examples 58 to 63 was tested and the test results are recorded in Table 30.

[0169] Table 30 Summary of test results of Examples 58 to 63 <![CDATA[Specific surface area / cm -1 > Aqueous solution potential window / V Embodiment 58 6120.4 3.3 Embodiment 59 4176.7 3.3 Embodiment 60 4023.4 3.4 Embodiment 61 43.9 3.6 Embodiment 62 67.2 3.6 Embodiment 63 36.5 3.2 Referring to Table 30, it can be seen from the results in Table 30 that the comprehensive performance of the diamond electrodes provided by Examples 58 to 63 can also reach a good level, which illustrates the feasibility of selecting different types of conductive diamond particles 2 to prepare diamond electrodes.

[0170] It should be noted that the resistivity of the diamond electrodes provided in Examples 58 to 63 was not measured because the deposited doped diamond coating and the doped diamond particles themselves were conductive in Examples 58 to 63, and mixing the conductive diamond particles 2 did not affect the film resistance of the doped diamond coating and the resistivity of the doped diamond particles. In addition, Table 29 does not limit the selection and combination of the conductive diamond particles 2, that is, any two or more conductive diamond particles 2 in Preparation Examples 1 to 51 can be selected and combined to prepare the diamond electrode.

[0171] In order to further verify the feasibility of selecting conductive diamond particles 2 with other particle sizes and shapes, the present application also provides preparation examples 52 to 57 and embodiments 64 to 69.

[0172] Preparation Example 52 Based on Preparation Example 3, the difference between this Preparation Example and Preparation Example 3 is that in this Preparation Example, silicon particles with an average particle size of 0.1 mm and a spherical shape are selected as heterogeneous material substrate particles after screening, and the deposition is stopped when the thickness of the deposited coating Ⅰ of micron-sized doped diamond grains is 5 μm; the remaining steps, conditions and parameters are consistent with those in Preparation Example 3.

[0173] Preparation Example 53 Based on Preparation Example 3, the difference between this Preparation Example and Preparation Example 3 is that in this Preparation Example, silicon particles with an average particle size of 1 mm and a tetrahedral shape are selected as heterogeneous material substrate particles after screening, and the deposition is stopped when the thickness of the deposited coating Ⅰ of micron-sized doped diamond grains is 5 μm; the remaining steps, conditions and parameters are consistent with those in Preparation Example 3.

[0174] Preparation Example 54 Based on Preparation Example 3, the difference between this Preparation Example and Preparation Example 3 is that in this Preparation Example, silicon particles with an average particle size of 5 mm and a spherical shape are selected as heterogeneous material substrate particles after screening, and the deposition is stopped when the thickness of the deposited coating Ⅰ of micron-sized doped diamond grains is 5 μm; the remaining steps, conditions and parameters are consistent with those in Preparation Example 3.

[0175] Preparation Example 55 Based on Preparation Example 3, the difference between this Preparation Example and Preparation Example 3 is that in this Preparation Example, silicon particles with an average particle size of 10 mm and a tetrahedral shape are selected as heterogeneous material substrate particles after screening, and the deposition is stopped when the thickness of the deposited coating Ⅰ of micron-sized doped diamond grains is 5 μm; the remaining steps, conditions and parameters are consistent with those in Preparation Example 3.

[0176] Preparation Example 56 Based on Preparation Example 3, the difference between this Preparation Example and Preparation Example 3 is that in this Preparation Example, silicon particles with an average particle size of 15 mm and a spherical shape are selected as heterogeneous material substrate particles after screening, and the deposition is stopped when the thickness of the deposited coating Ⅰ of micron-sized doped diamond grains is 5 μm; the remaining steps, conditions and parameters are consistent with those in Preparation Example 3.

[0177] Preparation Example 57 Based on Preparation Example 3, the difference between this Preparation Example and Preparation Example 3 is that in this Preparation Example, silicon particles with an average particle size of 20 mm and a tetrahedral shape are selected as heterogeneous material substrate particles after screening, and the deposition is stopped when the thickness of the deposited coating Ⅰ of micron-sized doped diamond grains is 5 μm; the remaining steps, conditions and parameters are consistent with those in Preparation Example 3.

[0178] Embodiments 64 to 69 Examples 64 to 69 respectively provide a diamond electrode prepared using the above-mentioned conductive diamond particles 2.

[0179] Based on Example 1, the difference between Examples 64 to 69 and Example 1 lies in the selection of conductive diamond particles 2, see Table 31; the remaining steps, conditions and parameters are consistent with those in Example 1.

[0180] Table 31 Selection of conductive diamond particles in Examples 64 to 69 Selected conductive diamond particles Embodiment 64 Preparation Example 52 Embodiment 65 Preparation Example 53 Embodiment 66 Preparation Example 54 Embodiment 67 Preparation Example 55 Embodiment 68 Preparation Example 56 Embodiment 69 Preparation Example 57 The electrode performance of the diamond electrodes provided in Examples 64 to 69 was tested and the test results are recorded in Table 32.

[0181] Table 32 Summary of test results of Examples 64 to 69 Resistivity / mΩ·cm <![CDATA[Specific surface area / cm -1 > Aqueous solution potential window / V Embodiment 64 8.1 4.2 3.6 Embodiment 65 8.7 48.0 3.6 Embodiment 66 8.2 6.2 3.6 Embodiment 67 8.3 4.5 3.6 Embodiment 68 8.5 1.5 3.6 Embodiment 69 8.7 0.8 3.6 Referring to Table 32, it can be seen from the results in Table 32 that, among the diamond electrodes provided in Examples 64 to 69, the specific surface area of ​​the diamond electrode provided in Example 65 is larger, which indicates that the specific surface area of ​​the diamond electrode shows a trend of first increasing and then decreasing with the particle size of the conductive diamond particles 2. Specifically, although in the diamond electrode provided in Example 64, the particle size of the conductive diamond particles 2 is too small, and the pores between the particles are also too small, the liquid cannot pass through the pores between the diamond particles due to surface tension, the contact area between the liquid and the diamond electrode is reduced, and the effective active specific surface area is close to that of a two-dimensional electrode; in the diamond electrode provided in Example 69, the specific surface area is less than 1 cm -1 At this time, the effective active area of ​​the diamond electrode is smaller than that of the two-dimensional electrode, and has no advantage. This shows that the diamond electrode prepared by using conductive diamond particles 2 of a specific particle size has advantages.

[0182] In order to further verify the feasibility of preparing diamond electrodes using a basket 1 made of other materials, the present application also provides Examples 70 to 71.

[0183] Embodiment 70 Based on Example 1, the difference between this example and Example 1 is that the material of the enclosure basket 1 used in this example is silicon carbide; at this time, the enclosure basket 1 can be a rigid enclosure basket; the remaining steps, conditions and parameters are consistent with those in Example 1.

[0184] Embodiment 71 Based on Example 1, the difference between this example and Example 1 is that the material of the surrounding basket 1 used in this example is metal titanium, and a layer of diamond coating is deposited on the surface of the surrounding basket 1 made of metal titanium.

[0185] The electrode performance of the diamond electrodes provided in Examples 70 to 71 was tested and the test results are recorded in Table 33.

[0186] Table 33 Summary of test results of Examples 70 to 71 Resistivity / mΩ·cm <![CDATA[Specific surface area / cm -1 > Aqueous solution potential window / V Embodiment 70 45.2 45.1 3.4 Embodiment 71 45.2 45.2 3.4 Referring to Table 33, it can be seen from the results of Table 33 that the comprehensive performance of the diamond electrodes provided by Examples 70 to 71 is good, and the performance of the diamond electrodes provided by Examples 70 to 71 is not much different from that of Example 1, which illustrates the feasibility of using a basket 1 made of different materials.

[0187] In summary, the diamond electrode provided in this application has good advantages.

[0188] Furthermore, in order to verify that the diamond electrode provided in the present application can be normally used in a working environment and can achieve internal cleaning of the diamond electrode and reuse after cleaning, the present application also provides Application Examples 1 to 2 for different application scenarios, and Application Examples 1 to 2 respectively provide two cleaning modes for the diamond electrode.

[0189] Application Example 1 This application example uses the diamond electrode provided in Example 1 to verify the feasibility.

[0190] The diamond electrode provided in Example 1 is applied to sewage purification, and the electrode potential window (CV curve) of the diamond electrode is detected. When the peak current of the CV curve increases or decreases by 20%, the diamond electrode is cleaned. The cleaning method used in this application example is a conventional diamond electrode cleaning method, that is, the positive and negative electrodes of the diamond electrode are swapped to perform surface self-cleaning of the diamond electrode.

[0191] The performance of the cleaned diamond electrode was tested and the resistivity was 48.7 mΩ·cm and the specific surface area was 43.2 cm -1 , the aqueous solution potential window is 3.4V. Compared with the electrode performance test results of Example 1 recorded in Table 3, it can be seen that the resistivity of the diamond electrode after cleaning increased by 7.7%, the effective active area of ​​the electrode decreased by 4.2%, and the aqueous solution potential window did not change. It can be seen that the diamond electrode provided by the present application can also perform good surface self-cleaning.

[0192] Application Example 2 This application example uses the diamond electrode provided in Example 1 to verify the feasibility.

[0193] The diamond electrode provided in Example 1 is applied to the degradation of carbon dioxide. When the pores between the conductive diamond particles 2 are blocked, the diamond electrode is cleaned by a cleaning method unique to the present application, specifically: The compacted conductive diamond particles 2 in the diamond electrode are disassembled and taken out from the surrounding basket 1, and each conductive diamond particle 2 is placed in an ultrasonic cleaning machine for ultrasonic cleaning; after cleaning, the cleaned conductive diamond particles 2 are placed back in the surrounding basket 1 and compacted by vibration, thereby completing the cleaning of the diamond electrode.

[0194] The performance of the cleaned diamond electrode was tested and the resistivity was 45.8 mΩ·cm and the specific surface area was 44.6 cm -1, the aqueous solution potential window is 3.4V, and compared with the electrode performance test results of Example 1 recorded in Table 3, it can be seen that the resistivity, specific surface area and aqueous solution potential window of the cleaned diamond electrode do not change by more than 2%. It can be seen that the diamond electrode provided by the present application can be cleaned by a unique cleaning method, and has a better effect than self-cleaning the surface of the diamond electrode.

[0195] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A diamond electrode, characterized in that: The invention comprises a surrounding basket and conductive diamond particles. The surrounding basket is provided with holes to form a mesh surrounding basket. The hole diameter is smaller than the particle diameter of the conductive diamond particles. The conductive diamond particles are placed in the surrounding basket.

2. The diamond electrode according to claim 1, characterized in that The conductive diamond particles include at least one of heterogeneous material substrate particles, diamond substrate particles and doped diamond particles; wherein the surfaces of the heterogeneous material substrate particles and the diamond substrate particles are both deposited with doped diamond coatings.

3. The diamond electrode according to claim 1, characterized in that The particle size of the conductive diamond particles is 0.5 to 15 mm.

4. The diamond electrode according to claim 2, characterized in that The doped diamond coating is a coating I of micron-scale doped diamond grains or a coating I of nano-scale doped diamond grains.

5. The diamond electrode according to claim 4, characterized in that The doped diamond coating is the coating I of the micron-sized doped diamond grains, and the surface of the coating I of the micron-sized doped diamond grains has micro-pits I.

6. The diamond electrode according to claim 4, characterized in that The doped diamond coating is a coating I of nanoscale doped diamond grains, and the coating I of nanoscale doped diamond grains is a porous structure I.

7. The diamond electrode according to claim 2, characterized in that The doped diamond coating includes a first coating and a second coating, wherein the first coating is a coating II of micron-scale doped diamond grains, and the second coating is a coating II of nano-scale doped diamond grains, and the second coating is deposited on the first coating; The surface of the first coating has micro-pits II, and the second coating has a porous structure II.

8. The diamond electrode according to any one of claims 1 to 7, characterized in that: The resistivity ρ(basket) of the enclosure and the resistivity ρ(conductive diamond particles) of the conductive diamond particles satisfy the following relationship: ρ(basket)≥ρ(conductive diamond particles).

9. A method for preparing a diamond electrode according to claim 1, characterized in that: The steps include: S1, preparing a basket; preparing conductive diamond particles; S2. Placing the conductive diamond particles in the enclosure basket, wherein the enclosure basket defines the shape of the conductive diamond particles stacked to obtain a diamond electrode.

10. The method for preparing a diamond electrode according to claim 9, characterized in that: In the step S1, preparing the conductive diamond particles includes: preparing at least one of heterogeneous material substrate particles with a doped diamond coating deposited on the surface, preparing diamond substrate particles with a doped diamond coating deposited on the surface, and preparing doped diamond particles.

11. The method for preparing a diamond electrode according to claim 10, characterized in that: The preparation of the heterogeneous material substrate particles with the doped diamond coating deposited on the surface comprises: Step 1: taking a heterogeneous material substrate particle and pre-placing a diamond seed crystal on the surface of the heterogeneous material substrate particle; Step 2: using chemical vapor deposition and introducing doping elements into the deposition atmosphere used in the chemical vapor deposition method, depositing a doped diamond coating on the surface of the heterogeneous material substrate particles, thereby obtaining heterogeneous material substrate particles with the doped diamond coating deposited on the surface.

12. The method for preparing a diamond electrode according to claim 10, characterized in that: The preparation of the diamond substrate particles with the doped diamond coating deposited on the surface comprises: Step 1, taking diamond substrate particles; Step 2: using chemical vapor deposition and introducing doping elements into the deposition atmosphere used in the chemical vapor deposition method, depositing a doped diamond coating on the surface of the diamond substrate particles, and obtaining diamond substrate particles with the doped diamond coating deposited on the surface.

13. The method for preparing a diamond electrode according to claim 11 or 12, wherein the chemical vapor deposition method is selected from a direct current arc plasma jet chemical vapor deposition method, and the doping element is selected from B.

14. The method for preparing a diamond electrode according to claim 13, characterized in that: The parameters of the DC arc plasma jet chemical vapor deposition method are as follows: In the deposition atmosphere: the hydrogen flow rate is 6-10 SLM, the argon flow rate is 2.5-6 SLM, and the methane flow rate is CH4 / H2=1-2%, forming a CH4 / H2 / Ar deposition atmosphere; B is introduced into the CH4 / H2 / Ar deposition atmosphere, and the B doping amount is B / C=3000-15000 ppm; The deposition temperature is 780-950° C., and the deposition pressure is 2.5-4.5 kPa. At this time, the doped diamond coating is obtained by deposition, and the doped diamond coating is a coating I of micron-sized doped diamond grains.

15. The method for preparing a diamond electrode according to claim 14, characterized in that: After the deposition is completed, the introduction of methane and B is suspended in the CH4 / H2 / Ar deposition atmosphere to form a H2 / Ar etching atmosphere; in the H2 / Ar etching atmosphere: the hydrogen flow rate is 6-10SLM, the argon flow rate is 2.5-5SLM; the etching temperature is 750-1050°C, the etching pressure is 2.8-4.5kPa, and the etching time is 5-30min; at this time, the surface of the coating Ⅰ of the micron-sized doped diamond grains obtained by deposition has micro-pits Ⅰ.

16. The method for preparing a diamond electrode according to claim 13, characterized in that: The parameters of the DC arc plasma jet chemical vapor deposition method are as follows: In the deposition atmosphere: the hydrogen flow rate is 7 to 9 SLM, the argon flow rate is 2.5 to 5 SLM, and the methane flow rate is CH4 / H2=4 to 8%, forming a CH4 / H2 / Ar deposition atmosphere; B is introduced into the CH4 / H2 / Ar deposition atmosphere, and the B doping amount is B / C=3000 to 12000 ppm; the deposition temperature is 700 to 820°C, and the deposition pressure is 2.5 to 4.5 kPa; at this time, the doped diamond coating is deposited, and the doped diamond coating is a coating I of nanoscale doped diamond grains.

17. The method for preparing a diamond electrode according to claim 16, characterized in that: During the deposition process, after 5 to 15 minutes of deposition, the introduction of methane and B are suspended in the CH4 / H2 / Ar deposition atmosphere to form a H2 / Ar etching atmosphere, and hydrogen plasma etching is performed, and the etching time is 1 / 4 to 1 / 3 of the deposition time; after the etching is completed, methane is continued to be introduced into the H2 / Ar etching atmosphere and B is introduced, and deposition and etching are performed alternately; at this time, the coating I of the nanoscale doped diamond grains obtained by deposition is a porous structure I.

18. The method for preparing a diamond electrode according to claim 13, characterized in that: The DC arc plasma jet chemical vapor deposition method comprises the following steps: A1. In the deposition atmosphere, the hydrogen flow rate is 6-10 SLM, the argon flow rate is 2.5-6 SLM, and the methane flow rate is CH4 / H2=1-2%, forming a CH4 / H2 / Ar deposition atmosphere; B is introduced into the CH4 / H2 / Ar deposition atmosphere, and the B doping amount is B / C=3000-15000 ppm; The deposition temperature is 780-950°C and the deposition pressure is 2.5-4.5 kPa; A2, suspending the introduction of methane and B to form a H2 / Ar etching atmosphere; in the H2 / Ar etching atmosphere: the hydrogen flow rate is 6-10SLM, the argon flow rate is 2.5-5SLM; the etching temperature is 750-1050°C, the etching pressure is 2.8-4.5kPa, and the etching time is 5-30min; A3, continue to introduce methane and introduce B to form a CH4 / H2 / Ar deposition atmosphere; in the CH4 / H2 / Ar deposition atmosphere, the hydrogen flow rate is 7-9SLM, the argon flow rate is 2.5-5SLM, the methane flow rate is CH4 / H2=4-8%, and the B doping amount is B / C=3000-12000ppm; the deposition temperature is 700-820°C, the deposition pressure is 2.5-4.5kPa, and the deposition time is 5-15min; A4, suspend the introduction of methane and B, form a H2 / Ar etching atmosphere, and perform hydrogen plasma etching. The etching time is 1 / 4 to 1 / 3 of the deposition time; Return to step A3 to perform deposition and etching alternately; At this time, the doped diamond coating is deposited, and the doped diamond coating includes a first coating and a second coating, the first coating is a coating II of micron-scale doped diamond grains, the second coating is a coating II of nano-scale doped diamond grains, and the second coating is deposited on the first coating; The surface of the first coating has micro-pits II, and the second coating has a porous structure II.

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