A diamond electrode and its preparation method

Abstract

The present application discloses a diamond electrode and a method for preparing the same. The diamond electrode comprises a basket and conductive diamond particles. The basket is provided with holes, forming a mesh basket, wherein the holes have a diameter smaller than the diameter of the conductive diamond particles; the conductive diamond particles are placed within the basket. The method for preparing the diamond electrode comprises preparing the conductive diamond particles; preparing the basket; and placing the conductive diamond particles within the basket, wherein the basket defines the shape of the conductive diamond particles, thereby producing the diamond electrode. The advantage of the present application is that the diamond electrode provided herein has a large specific surface area, and its interior can be disassembled for cleaning. After cleaning, it can be reassembled for reuse without compromising performance.

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 due to 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, traditional diamond electrodes made from doped diamond are mostly two-dimensional electrodes, resulting in a low specific surface area. This low specific surface area limits the mass transfer efficiency of the diamond electrode surface. Furthermore, traditional diamond electrodes are mostly enclosed monolithic units, making them difficult to clean when clogged or poisoned. Furthermore, the same diamond electrode cannot be used in multiple operating conditions, hindering its optimal mass transfer efficiency and limiting its flexibility. Furthermore, the high production cost of traditional diamond electrodes makes them unsuitable for large-scale industrial production.

[0004] Therefore, there is an urgent need for a diamond electrode with a high specific surface area, easy to clean, suitable for a variety of working conditions and low preparation cost to solve the problems existing in the existing technology. 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 various 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 aperture of the holes is smaller than the particle size 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 a 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 the conductive diamond particles and between the conductive diamond particles and the basket is replaced by directly placing the conductive diamond particles, thereby achieving separation between the conductive diamond particles and between the conductive diamond particles and the basket. Therefore, after removing the conductive diamond particles from the basket, the conductive diamond particles and the basket can be cleaned, thereby achieving cleaning of the interior of the diamond electrode, which can effectively alleviate the phenomena 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 replaced in the cleaned basket for reuse of the diamond electrode, overcoming the defect in the prior art that the traditional diamond electrode is difficult to clean when it 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 stack with 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 in 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 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 is, the low specific surface area and low mass transfer efficiency 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 large-area diamond electrodes due to the monolithic setting of the diamond electrode.

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

[0011] By adopting the above technical solution, the working part of the monolithic diamond electrode is converted into independent, mutually separable conductive diamond particles, and the conductive diamond particles in the diamond electrode provided by the present application can be prepared separately. In this way, the preparation of the monolithic diamond electrode can be converted into the preparation of individual conductive diamond particles, 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 above 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. 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. It 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 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 by the present application.

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

[0023] ρ(basket)≥ρ(conductive diamond particles).

[0024] 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. In this way, the basket can only play the role of restricting the shape and position of the accumulation of conductive diamond particles, and the basket further restricts the overall shape of the diamond electrode provided by the present application.

[0025] In a second aspect, the present application provides a method for preparing the above-mentioned diamond electrode, comprising the following steps:

[0026] S1. preparing a basket; preparing conductive diamond particles;

[0027] S2. Placing the conductive diamond particles in the enclosure basket, wherein the enclosure basket defines the shape of the conductive diamond particles stacked to produce a diamond electrode.

[0028] By adopting the above technical solution, first, 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; second, the prepared conductive diamond particles are placed inside the basket so that the conductive diamond particles are in contact with each other, thereby achieving connectivity between the conductive diamond particles, so that the diamond electrode provided by the present application can function as an electrode; third, the basket defines the shape of the accumulation of the conductive diamond particles, making the diamond electrode provided by the present application a three-dimensional electrode, thereby making the diamond electrode prepared by the preparation method of the diamond electrode provided by the present application have a high specific surface area; fourth, the basket only defines the shape of the accumulation of the conductive diamond particles, and does not adopt a method of fixed connection between each other, so that the conductive diamond particles inside the basket can be removed and cleaned, thereby overcoming the problem in the prior art that it is difficult to clean the diamond electrode.

[0029] Optionally, in 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.

[0030] By adopting the above technical solution, different types of conductive diamond particles can be selected according to specific working conditions; at the same time, the conductive diamond particles can be prepared separately, thereby effectively overcoming the limitation of the deposition area of ​​the diamond coating caused by the monolithic setting of the diamond electrode, thereby realizing the preparation of large-area diamond electrodes.

[0031] Optionally, preparing the heterogeneous material substrate particles with the doped diamond coating deposited on the surface includes:

[0032] Step 1: taking a heterogeneous material substrate particle and pre-placing a diamond seed crystal on the surface of the heterogeneous material substrate particle;

[0033] Step 2: using chemical vapor deposition and introducing doping elements into the deposition atmosphere used in the chemical vapor deposition method to deposit 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.

[0034] By adopting the above technical solution, first, diamond seed crystals are pre-placed on the surface of the heterogeneous material substrate particles, which can improve the surface roughness of the heterogeneous material particles and the nucleation density of the doped diamond coating, thereby enhancing the film-base adhesion of the doped diamond coating on the heterogeneous material substrate particles; second, chemical vapor deposition is selected to deposit the doped diamond coating, which can achieve deposition of the doped diamond coating on the surface of the heterogeneous material substrate particles, thereby completely covering the surface of the heterogeneous material substrate particles, avoiding exposure of the base material of the heterogeneous material substrate particles, thereby corroding and causing the doped diamond coating to fall off; third, the introduction of doping elements can achieve the purpose of conductivity of the doped diamond coating, causing an electrochemical reaction on the surface of the doped diamond coating, thereby generating hydroxyl radicals to achieve oxidation or electrolysis of difficult-to-degrade pollutants.

[0035] Further optionally, in step one, the operation of pre-positioning 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-positioning 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.

[0036] By adopting the above technical solution, the surface of the heterogeneous material substrate particles is cleaned and diamond seed crystals are pre-placed, which can increase the nucleation density of the doped diamond coating 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.

[0037] Optionally, preparing the diamond substrate particles with the doped diamond coating deposited on the surface includes:

[0038] Step 1: taking diamond substrate particles;

[0039] Step 2: using chemical vapor deposition and introducing doping elements into the deposition atmosphere used in the chemical vapor deposition method to deposit a doped diamond coating on the surface of the diamond substrate particles to obtain diamond substrate particles with the doped diamond coating deposited on the surface.

[0040] By adopting the above technical solution, first, 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 disconnection caused by contact between the diamond substrate particles; second, the introduction of doping elements can achieve the purpose of conductive doped diamond coating, so that the surface of the doped diamond coating undergoes electrochemical reaction, thereby generating hydroxyl radicals to achieve oxidation or electrolysis of difficult-to-degrade pollutants.

[0041] 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.

[0042] By adopting the above technical solution, the chemical vapor deposition method is further optimized to be 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 to be a low-energy level doping element B, which can make the deposited doped diamond coating have the characteristics of low resistivity. In addition, at a higher B doping amount, the deposited doped diamond coating can also have the ability to have metallic properties.

[0043] Optionally, the parameters of the DC arc plasma jet chemical vapor deposition method are as follows:

[0044] 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 coating I of micron-sized doped diamond grains.

[0045] 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 on micron-sized doped diamond grains.

[0046] Optionally, 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 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-etching pits I.

[0047] By adopting the above technical solution, the introduction of methane and B into the deposition atmosphere is suspended, and the surface of the coating I of the deposited micron-sized doped diamond grains can be subjected to hydrogen plasma etching. The micron-sized doped diamond grains are relatively large in size, 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 surface outcropping of the dislocations on the micron-sized doped diamond grains is etched, thereby forming micro-etching pits I, which increases the specific surface area of ​​the conductive diamond particles, thereby further increasing the specific surface area of ​​the diamond electrode provided by the present application.

[0048] Optionally, the parameters of the DC arc plasma jet chemical vapor deposition method are as follows:

[0049] 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 coating I of nano-scale doped diamond grains.

[0050] 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 on nano-scale doped diamond grains.

[0051] Optionally, during the deposition process, after 5 to 15 minutes of deposition, the introduction of methane and the introduction of B are suspended in the CH4 / H2 / Ar deposition atmosphere to form an 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.

[0052] By adopting the above technical solution, the introduction of methane and B is suspended in the deposition atmosphere, and the introduction of methane and B are alternately performed, so that during the growth process of the coating 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 graphite content between each grain is relatively high. Therefore, during the hydrogen plasma etching treatment, the graphite between each nano-scale doped diamond grain is etched, so that the graphite content is reduced and the potential window is increased; at the same time, holes are also formed in the coating I of the nano-scale doped diamond grains. Therefore, the coating I of the nano-scale doped diamond grains finally obtained has a porous structure I, which can increase the specific surface area of ​​the conductive diamond particles, thereby further increasing the specific surface area of ​​the diamond electrode provided by the present application.

[0053] Optionally, the DC arc plasma jet chemical vapor deposition method includes the following steps:

[0054] 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;

[0055] A2. Suspend the introduction of methane and B to form a H2 / Ar etching atmosphere; in the H2 / Ar etching atmosphere: the hydrogen flow rate is 6-10 SLM, the argon flow rate is 2.5-5 SLM; the etching temperature is 750-1050°C, the etching pressure is 2.8-4.5 kPa, and the etching time is 5-30 min;

[0056] 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 7-9 SLM, the argon flow rate is 2.5-5 SLM, the methane flow rate is CH4 / H2=4-8%, and the B doping amount is B / C=3000-12000 ppm; the deposition temperature is 700-820°C, the deposition pressure is 2.5-4.5 kPa, and the deposition time is 5-15 min;

[0057] A4, suspending the introduction of methane and B to form an H2 / Ar etching atmosphere, performing hydrogen plasma etching, and the etching time is 1 / 4 to 1 / 3 of the deposition time; returning to step A3 to alternately perform deposition and etching;

[0058] 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, 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 is a porous structure II.

[0059] By adopting the above technical solution, first, a coating II of micron-sized doped diamond grains is deposited, and the surface of the deposited coating II of micron-sized doped diamond grains is etched to obtain a first coating having micro-pits II on the surface; then, the first coating is used as a transition layer for a second coating to deposit a coating II of nano-sized doped diamond grains having a porous structure II. This can effectively improve the film-base adhesion of the second coating and, at the same time, can also expose smaller doped diamond grains 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 increasing the specific surface area of ​​the diamond electrode provided in the present application.

[0060] In summary, the present invention includes at least one of the following beneficial technical effects:

[0061] 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. This allows for separation of the conductive diamond particles from each other and from the basket. That is, after removing the conductive diamond particles from the basket, the conductive diamond particles and the basket can be cleaned, thereby cleaning the interior of the diamond electrode. After cleaning, the cleaned conductive diamond particles can be replaced in the cleaned basket for reuse, overcoming the defect in the prior art that the interior of the diamond electrode is difficult to clean when the traditional diamond electrode is arranged in a monolithic manner.

[0062] 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.

[0063] 3. In the diamond electrode provided in the present application, there are holes on the basket, and pores are formed between the conductive diamond particles by accumulation. The pores and the holes on the 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 ​​traditional diamond electrodes in the prior art when they are two-dimensional electrodes.

[0064] 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 basket and the number of conductive diamond particles placed can also be changed to make the usage scenarios of the diamond electrode provided in the present application varied and applicable to different working conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0065] Figure 1 This is a schematic structural diagram of the diamond electrode provided in Example 1.

[0066] 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.

[0067] Figure 3 This is an electron microscope image (micron crystal + etching) of the surface of silicon particles with a doped diamond coating deposited on the surface provided in Preparation Example 13.

[0068] Figure 4 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 19; (nanocrystal).

[0069] 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).

[0070] 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).

[0071] Explanation of the accompanying drawings: 1. basket; 2. conductive diamond particles. DETAILED DESCRIPTION

[0072] The present application is further described in detail below with reference to the accompanying drawings and examples.

[0073] The present application designs a diamond electrode, comprising a basket 1 and conductive diamond particles 2. The basket 1 is provided with holes to form a mesh basket, and the aperture of the holes is smaller than the particle size of the conductive diamond particles 2; the conductive diamond particles 2 are placed in the basket 1.

[0074] The diamond electrode of the present application is prepared by the following method, comprising the following steps:

[0075] S1, preparing a basket 1; preparing conductive diamond particles 2;

[0076] 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.

[0077] While improving electrode materials, the inventors of this application discovered that existing diamond electrodes typically utilize a closed, monolithic design. This design suffers from the following drawbacks: When a blockage or poisoning occurs within the diamond electrode, it is difficult to disassemble and clean. Alternatively, after disassembly and cleaning, the interior is difficult to reassemble and reuse, and the performance of the cleaned diamond electrode is easily compromised. Furthermore, during the preparation process, diamond electrodes using this design are limited by the deposition size, resulting in a relatively small specific surface area and size.

[0078] Therefore, the applicant 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 conductive diamond particles 2 are placed in the basket 1, which realizes the detachable interior of the diamond electrode. At the same time, the use of the basket 1 to limit the stacking shape of the conductive diamond particles 2 can 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. Together with the holes opened on the basket 1, when the diamond electrode provided by this application processes liquid, the liquid can pass through the interior of the diamond electrode, further improving the mass transfer efficiency, greatly increasing the contact area between the liquid and the diamond electrode, and achieving an increase in the specific surface area of ​​the diamond electrode. Specific embodiments

[0080] In the preparation examples and embodiments, the “deposition atmosphere” refers to the atmosphere formed by the gases introduced during chemical vapor deposition.

[0081] When testing the performance of the diamond electrode provided in the embodiments of the present application, the test items and methods are as follows:

[0082] 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 their surfaces, a four-point probe method is used for measurement. The operation is as follows: To facilitate measurement, a test sample is placed in a deposition chamber, and the doped diamond coating is deposited simultaneously with the heterogeneous material substrate particles or diamond substrate particles. After deposition, the resistivity of the doped diamond coating on the surface of the test sample is measured using the four-point probe method. The test sample is made of the same material as the heterogeneous material substrate particles or diamond substrate particles used for deposition, and the test sample is 5 mm × 5 mm in size.

[0083] 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: take the doped diamond particles, cut and polish them into diamond sheets with parallel upper and lower surfaces, and test the current in the circuit by applying voltage on the upper and lower surfaces, and use the formula Calculated; where S is the cross-sectional area of ​​the diamond sheet and L is the thickness of the diamond sheet;

[0084] 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, calculated using the chronocoulometry method. The test solution is 0.1M KCl / 0.1mM K3[Fe(CN)6];

[0085] 3. Aqueous solution potential window: measured by current-cyclic voltammetry, with a diamond electrode as the working electrode, a Pt electrode as the auxiliary electrode, a saturated calomel electrode as the reference electrode, a 0.2 M Na2SO4 solution, and a cyclic scan rate of 0.1 V / s.

[0086] 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.

[0087] Preparation Examples 1 to 10

[0088] Preparation Examples 1 to 10 respectively provide a heterogeneous material substrate particle with a coating I having micron-sized doped diamond grains deposited on the surface.

[0089] Preparation Example 1

[0090] Silicon blocks are selected, crushed and then sieved, and silicon particles with an average particle size of 0.5 mm and an octahedral shape are selected as heterogeneous material substrate particles;

[0091] The silicon particles are cleaned and ultrasonically treated in a diamond powder suspension 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;

[0092] Silicon particles with diamond seed crystals pre-disposed on their surfaces were 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 were as follows:

[0093] The hydrogen flow rate is 10 SLM, the argon flow rate is 2.5 SLM, 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=3000 ppm; the deposition temperature is 780°C, the deposition pressure is 2.5 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, which are silicon particles with a coating I of micron-sized doped diamond grains deposited on the surface.

[0094] Preparation Examples 2 to 5

[0095] Based on Preparation Example 1, Preparation Examples 2-5 differ from Preparation Example 1 in that different parameters were used during the deposition of Coating I, which contained micron-sized doped diamond grains. The remaining steps, conditions, and parameters were consistent with those in Preparation Example 1. Specifically, the parameters used in Preparation Examples 2-5 are shown in Table 1.

[0096] Table 1 Summary of parameters of preparation examples 2 to 5

[0097] 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

[0098] Preparation Example 6

[0099] Based on Preparation Example 1, this Preparation Example differs from Preparation Example 1 in that a different chemical vapor deposition method is used in this Preparation Example to deposit the coating I of micron-sized doped diamond grains. The specific operation is as follows:

[0100] Silicon particles with diamond seed crystals pre-disposed on their surfaces 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:

[0101] 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, where the source of B is selected from diborane and the B doping amount is B / C=8000 ppm; the deposition temperature is 800°C and the deposition pressure is 4.0 kPa. When the thickness of the deposited coating I of micron-sized doped diamond grains reaches 5 μm, the deposition is stopped to obtain conductive diamond particles 2, which are silicon particles having a coating I of micron-sized doped diamond grains deposited on their surfaces;

[0102] The remaining steps, conditions and parameters are consistent with those in Preparation Example 1.

[0103] Examples 1 to 10

[0104] 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.

[0105] Example 1

[0106] The silicon particles prepared in Preparation Example 1 and having coating Ⅰ deposited on the surface with micron-sized doped diamond grains are selected as conductive diamond particles 2;

[0107] Polyethylene resin is selected and woven into a basket 1. The diameter of the holes in 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.

[0108] 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 contact each other, and the conductive diamond particles 2 are vibrated to achieve close contact between the conductive diamond particles 2, thereby producing a diamond electrode.

[0109] Examples 2 to 6

[0110] 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.

[0111] Table 2 Selection of conductive diamond particles in Examples 2 to 6

[0112] 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

[0113] The electrode performance of the diamond electrodes provided in Examples 1 to 6 was tested, and the test results are recorded in Table 3.

[0114] Table 3 Summary of test results of Examples 1 to 6

[0115] 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

[0116] As shown in Table 3, the specific surface area of ​​the diamond electrodes provided in Examples 1 to 6 is 43.5 cm -1 The above results show that the aqueous solution potential window is between 3.3 and 3.6 V. Regarding resistivity, Example 1 has a higher resistivity than Examples 2 to 6. This is because resistivity is primarily determined by the boron doping level. When the boron doping level is low, the impact on the resistivity of the diamond electrode is greater. When the boron doping level reaches a certain value, the boron doping level is essentially saturated, at which point the impact on the resistivity of the diamond electrode is smaller. Therefore, as the boron doping level increases, the rate of change of resistivity decreases significantly. However, according to the results in Table 3, the diamond electrodes provided by Examples 1 to 6 still have good overall performance.

[0117] Specifically, although the diamond electrode provided in Example 6 has better overall 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, among 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.

[0118] Preparation Examples 7 to 10

[0119] 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.

[0120] Examples 7 to 10

[0121] 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.

[0122] Table 4 Selection of conductive diamond particles in Examples 7 to 10

[0123] Selected conductive diamond particles Example 7 Preparation Example 7 Example 8 Preparation Example 8 Example 9 Preparation Example 9 Example 10 Preparation Example 10

[0124] The electrode performance of the diamond electrodes provided in Examples 7 to 10 was tested, and the test results are recorded in Table 5.

[0125] Table 5 Summary of test results of Examples 7 to 10

[0126] 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

[0127] As shown in Table 5, when using heterogeneous material substrate particles of the same average particle size, the resistivity, specific surface area, and aqueous solution potential window of the diamond electrode do not change significantly with increasing thickness of the coating layer I of micron-sized doped diamond grains deposited on the surface of the heterogeneous material substrate particles. Comparing the test results of Example 3 with those of Examples 7-10, 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, resulting in superior overall electrode performance. Specifically, the diamond electrode prepared using the conductive diamond particles 2 prepared in Preparation Example 3 exhibits superior performance.

[0128] Preparation Examples 11 to 16

[0129] Preparation Examples 11 to 16 respectively provide a heterogeneous material substrate particle having a coating layer I deposited with micron-sized doped diamond grains on the surface, and micro-etching pits I on the surface of the coating layer I of micron-sized doped diamond grains.

[0130] Preparation Example 11

[0131] 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:

[0132] 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, and 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-etching pits I; the remaining steps, conditions and parameters are consistent with those in Preparation Example 3.

[0133] Preparation Examples 12 to 15

[0134] Based on Preparation Example 11, Preparation Examples 12-15 differ from Preparation Example 11 in that different parameters were used during the hydrogen plasma etching of Coating I, which contained micron-sized doped diamond grains. The remaining steps, conditions, and parameters were consistent with those in Preparation Example 11. Specifically, the parameters used in Preparation Examples 12-15 are shown in Table 6.

[0135] Table 6 Summary of parameters of Preparation Examples 12 to 15

[0136] 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

[0137] Preparation Example 16

[0138] 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:

[0139] 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 0.5 SLM; the etching temperature is 800°C, the etching pressure is 3.8 kPa, and the etching time is 30 min; 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-etching pits I.

[0140] The remaining steps, conditions and parameters are consistent with those in Preparation Example 6.

[0141] Examples 11 to 16

[0142] Examples 11 to 16 respectively provide a diamond electrode prepared from silicon particles having the 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.

[0143] 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.

[0144] Table 7 Selection of conductive diamond particles in Examples 11 to 16

[0145] Selected conductive diamond particles Example 11 Preparation Example 11 Example 12 Preparation Example 12 Example 13 Preparation Example 13 Example 14 Preparation Example 14 Example 15 Preparation Example 15 Example 16 Preparation Example 16

[0146] The electrode performance of the diamond electrodes provided in Examples 11 to 16 was tested, and the test results are recorded in Table 8.

[0147] Table 8 Summary of test results of Examples 11 to 16

[0148] Resistivity / mΩ·cm <![CDATA[Specific surface area / cm -1 > Aqueous solution potential window / V Example 11 8.6 82.7 3.6 Example 12 8.7 82.1 3.6 Example 13 8.6 84.7 3.6 Example 14 8.6 81.6 3.6 Example 15 8.6 80.5 3.6 Example 16 6.1 74.0 3.6

[0149] Referring to Table 8, the results in Table 8 show that the resistivity and aqueous solution potential window of the diamond electrodes provided in Examples 11 to 15 are not significantly different from those provided in Example 3, and the specific surface area of ​​the diamond electrodes provided in Example 16 is significantly increased compared to that provided in Example 6. However, the specific surface area of ​​the diamond electrodes provided in Examples 11 to 15 is significantly increased compared to that provided in Example 3, and the specific surface area of ​​the diamond electrode provided in Example 16 is significantly increased compared to that provided in Example 6. This demonstrates 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 diamond electrode has better overall performance. Specifically, the test results of Examples 11 and 16 show that, using the same etching time, the specific surface area of ​​the diamond electrode provided in Example 16 is smaller than that of the diamond electrode provided in Example 11, indicating the superiority of the DC arc plasma jet chemical vapor deposition method.

[0150] Preparation Examples 17 to 26

[0151] 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.

[0152] Preparation Example 17

[0153] Based on Preparation Example 1, this Preparation Example differs from Preparation Example 1 in that: this Preparation Example deposits a coating I of nanoscale doped diamond grains on the surface of the heterogeneous material substrate particles. Compared with Preparation Example 1, the process parameters selected are different; specifically, the selected parameters are as follows:

[0154] 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, where the source of B is selected from borax and the B doping amount is B / C=3000 ppm; the deposition temperature is 700°C and the deposition pressure is 2.5 kPa. When the thickness of the deposited coating I of nanoscale doped diamond grains reaches 8 μm, the deposition is stopped to obtain conductive diamond particles 2, which are silicon particles having a coating I of nanoscale doped diamond grains deposited on their surfaces;

[0155] The remaining steps, conditions and parameters are consistent with those in Preparation Example 1.

[0156] Preparation Examples 18 to 21

[0157] Based on Preparation Example 17, Preparation Examples 18 to 21 differ from Preparation Example 17 in that different parameters were used during the deposition of Coating I, which contained nanoscale doped diamond grains. The remaining steps, conditions, and parameters were consistent with those in Preparation Example 17. Specifically, the parameters used in Preparation Examples 18 to 21 are shown in Table 9.

[0158] Table 9 Summary of parameters of Preparation Examples 18 to 21

[0159] 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

[0160] Preparation Example 22

[0161] 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, this Preparation Example uses a different chemical vapor deposition method. The specific operation is as follows:

[0162] Silicon particles with diamond seed crystals pre-disposed on their surfaces are placed in a microwave plasma chemical vapor deposition chamber to deposit a coating I of nanoscale doped diamond grains. Specifically, the parameters selected are as follows:

[0163] 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, where the source of B is selected from borax and the B doping amount is B / C=7800 ppm; the deposition temperature is 720°C and the deposition pressure is 4.0 kPa. When the thickness of the deposited coating I of nanoscale doped diamond grains reaches 8 μm, the deposition is stopped to obtain conductive diamond particles 2, wherein the conductive diamond particles 2 are silicon particles having a coating I of nanoscale doped diamond grains deposited on their surfaces;

[0164] The remaining steps, conditions and parameters are consistent with those in Preparation Example 17.

[0165] Examples 17 to 26

[0166] Examples 17 to 26 each provide a diamond electrode made from silicon particles having a coating I with nano-scale doped diamond grains deposited on the surface.

[0167] Examples 17 to 22

[0168] 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.

[0169] Table 10 Selection of conductive diamond particles in Examples 17 to 22

[0170] Selected conductive diamond particles Example 17 Preparation Example 17 Example 18 Preparation Example 18 Example 19 Preparation Example 19 Example 20 Preparation Example 20 Example 21 Preparation Example 21 Example 22 Preparation Example 22

[0171] The electrode performance of the diamond electrodes provided in Examples 17 to 22 was tested, and the test results are recorded in Table 11.

[0172] Table 11 Summary of test results of Examples 17 to 22

[0173]

[0174]

[0175] As shown in Table 11, the specific surface area of ​​the diamond electrodes provided in Examples 17 to 22 is 37.5 cm -1 The above results show that the aqueous solution potential window is between 3.1 and 3.2 V. Regarding resistivity, Example 17 has a higher resistivity than Examples 18 to 22. This is because resistivity is primarily determined by the boron doping level. When the boron doping level is low, the impact on the resistivity of the diamond electrode is greater. When the boron doping level reaches a certain value, the boron doping level is essentially saturated, at which point the impact on the resistivity of the diamond electrode is smaller. Therefore, as the boron doping level increases, the rate of change of resistivity decreases significantly. However, according to the results in Table 11, the diamond electrodes provided by Examples 17 to 22 still have good overall performance.

[0176] 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, among 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.

[0177] Preparation Examples 23 to 26

[0178] 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.

[0179] Examples 23 to 26

[0180] 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.

[0181] Table 12 Selection of conductive diamond particles in Examples 23 to 26

[0182] Selected conductive diamond particles Example 23 Preparation Example 23 Example 24 Preparation Example 24 Example 25 Preparation Example 25 Example 26 Preparation Example 26

[0183] The electrode performance of the diamond electrodes provided in Examples 23 to 26 was tested, and the test results are recorded in Table 13.

[0184] Table 13 Summary of test results of Examples 23 to 26

[0185] Resistivity / mΩ·cm <![CDATA[Specific surface area / cm -1 > Aqueous solution potential window / V Example 23 2.9 38.7 3.2 Example 24 2.7 38.9 3.2 Example 25 2.7 39.2 3.2 Example 26 2.6 39.6 3.2

[0186] Referring to Table 13, the results in Table 13 show that, when using heterogeneous material substrate particles of the same average particle size, the specific surface area of ​​the diamond electrode increases slightly with increasing thickness of the coating I of nanoscale doped diamond grains deposited on the surface of the heterogeneous material substrate particles, but the magnitude of the increase gradually decreases. By comparing the test results of Example 19 with those of 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 no reduction in the aqueous solution potential window, resulting in better overall electrode performance. However, 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 takes longer to deposit, so the diamond electrode prepared using the conductive diamond particles 2 prepared in Preparation Example 19 is more superior.

[0187] Preparation Examples 27-30

[0188] 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.

[0189] Preparation Example 27

[0190] Based on Preparation Example 19, this Preparation Example differs from Preparation Example 19 in that it further includes alternating deposition and hydrogen plasma etching of the coating I of the nanoscale doped diamond grains during the deposition process. The specific operations are as follows:

[0191] 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 an H2 / Ar etching atmosphere, and hydrogen plasma etching was performed for 1.25 minutes. After the etching was completed, methane was introduced and B was introduced in the H2 / Ar etching atmosphere, and deposition was continued for 5 minutes. The hydrogen plasma etching for 1.25 minutes and the deposition for 5 minutes were alternately performed. When the thickness of the deposited coating I of nanoscale doped diamond grains reached 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 had a porous structure I.

[0192] The remaining steps, conditions and parameters are consistent with those in Preparation Example 19.

[0193] Preparation Example 28

[0194] 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 alternately performed. 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 the same as those in Preparation Example 27.

[0195] Preparation Example 29

[0196] 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 alternately performed. 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 the same as those in Preparation Example 27.

[0197] Preparation Example 30

[0198] Based on Preparation Example 22, this Preparation Example differs from Preparation Example 22 in that: in this Preparation Example, the coating I of the nanoscale doped diamond grains during the deposition process is subjected to alternating deposition and hydrogen-argon plasma etching. The specific operations are as follows:

[0199] 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 an H2 / Ar etching atmosphere, and hydrogen plasma etching was performed for 5 minutes. After the etching was completed, methane was introduced and B was introduced into the H2 / Ar etching atmosphere, and deposition was continued for 15 minutes. The hydrogen plasma etching for 5 minutes and the deposition for 15 minutes were alternately performed. When the thickness of the deposited coating I of nanoscale doped diamond grains reached 8 μm, the deposition was stopped to obtain conductive diamond particles 2. At this time, the conductive diamond particles 2 were silicon particles having a coating I of nanoscale doped diamond grains deposited on the surface, and the coating I of the nanoscale doped diamond grains had a porous structure I.

[0200] The remaining steps, conditions and parameters are consistent with those in Preparation Example 22.

[0201] Examples 27 to 30

[0202] Examples 27 to 30 respectively provide a diamond electrode prepared from silicon particles having the above-mentioned 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.

[0203] 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.

[0204] Table 14 Selection of conductive diamond particles in Examples 27 to 30

[0205] Selected conductive diamond particles Example 27 Preparation Example 27 Example 28 Preparation Example 28 Example 29 Preparation Example 29 Example 30 Preparation Example 30

[0206] The electrode performance of the diamond electrodes provided in Examples 27 to 30 was tested, and the test results are recorded in Table 15.

[0207] Table 15 Summary of test results of Examples 27 to 30

[0208]

[0209]

[0210] 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 the diamond electrode provided in Example 19, and that of Example 30 is slightly increased compared with the diamond electrode provided in Example 22, and the aqueous solution potential window has no significant change. However, the specific surface area of ​​the diamond electrodes provided in Examples 27 to 29 is significantly increased compared with the diamond electrode provided in Example 19, and the specific surface area of ​​the diamond electrode provided in Example 30 is significantly increased compared with the diamond electrode 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 surface area of ​​the diamond electrode can be further increased by alternating deposition and hydrogen plasma etching of the coating layer I of nano-scale doped diamond grains deposited on the surface of the conductive diamond particles 2, and the overall performance of the diamond electrode is better.

[0211] 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 obtained by DC arc plasma jet chemical vapor deposition in the diamond electrodes provided in Examples 27 to 29, the coating I of the nano-scale doped diamond grains with a porous structure I grows slower, so the DC arc plasma jet chemical vapor deposition method is superior.

[0212] Preparation Examples 31 to 34

[0213] 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.

[0214] Preparation Example 31

[0215] Based on Preparation Example 1, this Preparation Example differs from Preparation Example 1 in 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-disposed 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:

[0216] A1. The hydrogen flow rate is 10 SLM, the argon flow rate is 2.5 SLM, and the methane flow rate is CH4 / H2=1%, forming a CH4 / H2 / Ar deposition atmosphere; a doping element B is introduced into the CH4 / H2 / Ar deposition atmosphere, where the source of B is selected from trimethyl borate and the B doping amount is B / C=3000 ppm; the deposition temperature is 780°C and the deposition pressure is 2.5 kPa, until the thickness of the deposited micron-sized doped diamond grain coating I reaches 10 μm;

[0217] A2. Stop the introduction of methane and B to form a H2 / Ar etching atmosphere: the hydrogen flow rate is 6 SLM, the argon flow rate is 5 SLM; the etching temperature is 750°C, the etching pressure is 2.8 kPa, and the etching time is 30 min;

[0218] A3. Continue to introduce methane and B to form a CH4 / H2 / Ar deposition atmosphere: the hydrogen flow rate is 9 SLM, the argon flow rate is 2.5 SLM, and the methane flow rate is CH4 / H2 = 4%; introduce the doping element B into the CH4 / H2 / Ar deposition atmosphere, and the B doping amount is B / C = 3000 ppm; the deposition temperature is 700°C, the deposition pressure is 2.5 kPa, and the deposition time is 5 minutes;

[0219] A4, suspend the introduction of methane and the introduction of B, form an H2 / Ar etching atmosphere, and perform hydrogen plasma etching for 1.25 min;

[0220] Return to step A3 until the thickness of the deposited coating I of nano-scale doped diamond grains with porous structure I reaches 8 μm, and then stop the deposition and hydrogen plasma etching;

[0221] The remaining steps, conditions and parameters are consistent with those in Preparation Example 1.

[0222] Preparation Examples 32-33

[0223] 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.

[0224] Table 16 Summary of parameters of Preparation Examples 32 to 33

[0225]

[0226]

[0227] Preparation Example 34

[0228] 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. The specific operation is as follows:

[0229] Placing silicon particles with diamond seed crystals pre-disposed on their surfaces in a microwave plasma chemical vapor deposition chamber to deposit a first coating and a second coating comprises the following steps:

[0230] B1. A hydrogen flow rate of 0.5 SLM and a methane flow rate of CH4 / H2 = 1.5% are formed to form a CH4 / H2 deposition atmosphere; a doping element B is introduced into the CH4 / H2 deposition atmosphere, where the source of B is selected from trimethyl borate and the B doping amount is B / C = 8000 ppm; the deposition temperature is 800°C and the deposition pressure is 4 kPa, until the thickness of the deposited micron-sized doped diamond grain coating I reaches 10 μm;

[0231] B2. Stop the introduction of methane and B to form a H2 plasma etching atmosphere: the hydrogen flow rate is 0.5 SLM; the etching temperature is 800°C, the etching pressure is 3.8 kPa, and the etching time is 30 min;

[0232] B3. Continue to introduce methane and B to form a CH4 / H2 / Ar deposition atmosphere: the hydrogen flow rate is 0.1SLM, the argon flow rate is 0.3SLM, and 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℃, the deposition pressure is 4kPa, and the deposition time is 15min;

[0233] B4, suspend the introduction of methane and B, form an H2 / Ar etching atmosphere, and perform hydrogen plasma etching for 5 minutes;

[0234] Return to step B3 until the thickness of the deposited coating I of nano-scale doped diamond grains with porous structure I reaches 8 μm, and then stop the deposition and hydrogen plasma etching;

[0235] The remaining steps, conditions and parameters are consistent with those in Preparation Example 1.

[0236] Examples 31 to 34

[0237] Examples 31 to 34 respectively provide a diamond electrode prepared using the silicon particles with the first coating and the second coating deposited on the surface as described above.

[0238] 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.

[0239] Table 17 Selection of conductive diamond particles in Examples 31 to 34

[0240] Selected conductive diamond particles Example 31 Preparation Example 31 Example 32 Preparation Example 32 Example 33 Preparation Example 33 Example 34 Preparation Example 34

[0241] The electrode performance of the diamond electrodes provided in Examples 31 to 34 was tested, and the test results are recorded in Table 18.

[0242] Table 18 Summary of test results of Examples 31 to 34

[0243] Resistivity / mΩ·cm <![CDATA[Specific surface area / cm -1 > Aqueous solution potential window / V Example 31 45.4 7052.2 3.2 Example 32 6.8 8530.6 3.3 Example 33 5.7 6180.0 3.2 Example 34 7.6 7370.5 3.3

[0244] As shown in Table 18, the diamond electrodes provided by Examples 31-34 have larger specific surface areas than the diamond electrodes provided by Examples 1-30, and their aqueous solution potential windows are also between 3.2 and 3.3 V. Regarding resistivity, Example 31 has a higher resistivity than Examples 32-34. This is because resistivity is primarily determined by the boron doping level. When the boron doping level is low, the impact on the resistivity of the diamond electrode is greater. When the boron doping level reaches a certain value, the boron doping level is essentially saturated, at which point the impact on the resistivity of the diamond electrode is smaller. Therefore, as the boron doping level increases, the rate of change of resistivity decreases significantly. However, the results in Table 18 show that the diamond electrodes provided by Examples 31-34 still have good overall performance.

[0245] 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.

[0246] Electron microscopy

[0247] The surfaces of the silicon particles with doped diamond coatings deposited thereon 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.

[0248] 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 5As shown, the electron microscope image corresponding to Preparation Example 32 is as follows Figure 6 shown.

[0249] According to the results of electron microscopy, Figures 2 to 6 In the doped diamond coating shown, the doped diamond grains have no obvious defect points, the distribution of the doped diamond grains is relatively uniform, and the particle size uniformity of the doped diamond grains is relatively good.

[0250] 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 porosity of the coating I of the nano-scale doped diamond grains corresponding to Preparation Example 28 is higher, forming a porous structure I.

[0251] 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.

[0252] Preparation Examples 35 to 37

[0253] Preparation Examples 35 to 37 respectively provide conductive diamond particles 2 prepared from heterogeneous material substrate particles made of silicon carbide.

[0254] Preparation Example 35

[0255] 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 this Preparation Example selects silicon carbide blocks to replace silicon blocks; the remaining steps, conditions and parameters are consistent with Preparation Example 13.

[0256] Preparation Example 36

[0257] 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.

[0258] Preparation Example 37

[0259] 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.

[0260] Preparation Examples 38-40

[0261] Preparation Examples 38 to 40 respectively provide conductive diamond particles 2 prepared from heterogeneous material substrate particles of silicon nitride.

[0262] Preparation Example 38

[0263] 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 this Preparation Example selects silicon nitride blocks to replace silicon blocks; the remaining steps, conditions and parameters are consistent with Preparation Example 13.

[0264] Preparation Example 39

[0265] 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 this Preparation Example selects silicon nitride blocks to replace silicon blocks; the remaining steps, conditions and parameters are consistent with Preparation Example 28.

[0266] Preparation Example 40

[0267] 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 this Preparation Example selects silicon nitride blocks to replace silicon blocks; the remaining steps, conditions and parameters are consistent with Preparation Example 32.

[0268] Examples 35 to 40

[0269] 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.

[0270] Table 19 Selection of conductive diamond particles in Examples 35 to 40

[0271] Selected conductive diamond particles Example 35 Preparation Example 35 Example 36 Preparation Example 36 Example 37 Preparation Example 37 Example 38 Preparation Example 38 Example 39 Preparation Example 39 Example 40 Preparation Example 40

[0272] The electrode performance of the diamond electrodes provided in Examples 35 to 40 was tested, and the test results are recorded in Table 20.

[0273] Table 20 Summary of test results of Examples 35 to 40

[0274] Resistivity / mΩ·cm <![CDATA[Specific surface area / cm -1 > Aqueous solution potential window / V Example 35 8.9 86.3 3.6 Example 36 7.3 6348.6 3.3 Example 37 6.9 8472.7 3.3 Example 38 8.1 84.8 3.5 Example 39 6.5 6206.3 3.3 Example 40 6.5 8572.9 3.3

[0275] 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.

[0276] In order to further verify the feasibility of using other diamond powder suspensions to pre-place diamond seed crystals, this application also provides Preparation Examples 41 to 43 and Examples 41 to 43.

[0277] Preparation Example 41

[0278] 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 the same as those in Preparation Example 32.

[0279] Preparation Example 42

[0280] 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 the same as those in Preparation Example 37.

[0281] Preparation Example 43

[0282] 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.

[0283] Examples 41 to 43

[0284] 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.

[0285] Table 21 Selection of conductive diamond particles in Examples 41 to 43

[0286] Selected conductive diamond particles Example 41 Preparation Example 41 Example 42 Preparation Example 42 Example 43 Preparation Example 43

[0287] The electrode performance of the diamond electrodes provided in Examples 41 to 43 was tested, and the test results are recorded in Table 22.

[0288] Table 22 Summary of test results of Examples 41 to 43

[0289] Resistivity / mΩ·cm <![CDATA[Specific surface area / cm -1 > Aqueous solution potential window / V Example 41 6.8 8508.5 3.3 Example 42 6.9 8458.3 3.3 Example 43 6.6 8521.9 3.3

[0290] 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 when 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.

[0291] 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.

[0292] Examples 44 to 49

[0293] 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 the same as those in Example 1.

[0294] Table 23 Selection of conductive diamond particles in Examples 44 to 49

[0295] Selected conductive diamond particles Example 44 Preparation Example 3, Preparation Example 13 Example 45 Preparation Example 13, Preparation Example 19 Example 46 Preparation Example 19, Preparation Example 28 Example 47 Preparation Example 3, Preparation Example 13, Preparation Example 32 Example 48 Preparation Example 19, Preparation Example 28, Preparation Example 32 Example 49 Preparation Example 3, Preparation Example 13, Preparation Example 19, Preparation Example 28, Preparation Example 32

[0296] The electrode performance of the diamond electrodes provided in Examples 44 to 49 was tested, and the test results are recorded in Table 24.

[0297] Table 24 Summary of test results of Examples 44 to 49

[0298] <![CDATA[Specific surface area / cm -1 > Aqueous solution potential window / V Example 44 67.9 3.6 Example 45 63.4 3.3 Example 46 3108.9 3.2 Example 47 2866.8 3.3 Example 48 4932.7 3.2 Example 49 2987.6 3.2

[0299] 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.

[0300] It should be noted that the resistivity of the diamond electrodes provided in Examples 44-49 was not measured. This is because the conductivity in these diamond electrodes is due to the doped diamond coating deposited on the surface of the heterogeneous material substrate particles. Therefore, the resistivity of the diamond electrodes was measured using a four-point probe method, measuring the sheet resistance of the doped diamond coating. Mixing the conductive diamond particles 2 provided in different preparation examples did not change the sheet resistance of each conductive diamond particle 2. Furthermore, Table 23 does not limit the selection and combination of the conductive diamond particles 2. In other words, any combination of any two or more heterogeneous material substrate particles with doped diamond coatings deposited on their surfaces from Preparation Examples 1-43 can be used to prepare diamond electrodes.

[0301] In order to further verify the feasibility of preparing diamond electrodes by doping diamond coating with diamond substrate particles in addition to heterogeneous material substrate particles, this application also provides preparation examples 44 to 48 and embodiments 50 to 54.

[0302] Preparation Example 44

[0303] Based on Preparation Example 3, the difference between this Preparation Example and Preparation Example 3 is that: in this Preparation Example, diamond substrate particles are used to replace the heterogeneous material substrate particles, and the step of pre-setting diamond seed crystals is omitted; the remaining steps, conditions and parameters are consistent with those in Preparation Example 3, and diamond substrate particles with coating I deposited on the surface with micron-sized doped diamond grains are obtained.

[0304] Preparation Example 45

[0305] 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.

[0306] Preparation Example 46

[0307] 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 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 on the surface with nano-scale doped diamond grains are obtained.

[0308] Preparation Example 47

[0309] 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 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 are obtained, the surface of which is deposited with coating I of nano-scale doped diamond grains, and the coating I of nano-scale doped diamond grains is a porous structure I.

[0310] Preparation Example 48

[0311] 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 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.

[0312] Examples 50 to 54

[0313] 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.

[0314] 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.

[0315] Table 25 Selection of conductive diamond particles in Examples 50 to 54

[0316] Selected conductive diamond particles Example 50 Preparation Example 44 Example 51 Preparation Example 45 Example 52 Preparation Example 46 Example 53 Preparation Example 47 Example 54 Preparation Example 48

[0317] The electrode performance of the diamond electrodes provided in Examples 50 to 54 was tested, and the test results are recorded in Table 26.

[0318] Table 26 Summary of test results of Examples 50 to 54

[0319] Resistivity / mΩ·cm <![CDATA[Specific surface area / cm -1 > Aqueous solution potential window / V Example 50 8.7 49.7 3.6 Example 51 8.7 82.9 3.6 Example 52 3.1 37.4 3.3 Example 53 7.1 5987.9 3.4 Example 54 7.2 8023.6 3.4

[0320] 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. When 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. This illustrates the feasibility of preparing diamond electrodes by selecting diamond substrate particles for deposition of doped diamond coating.

[0321] 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, this application also provides Preparation Examples 49 to 51 and Examples 55 to 57.

[0322] Preparation Example 49

[0323] The method of synthesizing doped diamond particles using a high temperature and high pressure method includes the following steps:

[0324] Graphite is used as a carbon source and high-purity boron powder is used as a source of the doping element B. The graphite and boron powder are uniformly mixed while controlling the mass ratio of the boron element to the carbon element to be 4%. Under the condition of Fe-Ni as a catalyst, the reaction temperature is controlled to be 1300°C and the reaction pressure is controlled to be 4.5GPa. The reaction is carried out for 9 minutes to produce octahedral doped diamond particles. The above-mentioned doped diamond particles are sieved and doped diamond particles with an average particle size of 0.5 mm are selected.

[0325] Preparation Example 50

[0326] The method of synthesizing doped diamond particles using a high temperature and high pressure method includes the following steps:

[0327] Graphite is used as a carbon source, and high-purity boron powder is used as a source of the doping element B. The graphite and boron powder are uniformly mixed while controlling the mass ratio of the boron element to the carbon element to be 10%. Under the condition of Fe-Ni as a catalyst, the reaction temperature is controlled to be 1500°C, the reaction pressure is controlled to be 7GPa, and the reaction is carried out for 5 minutes to produce octahedral doped diamond particles. The above-mentioned doped diamond particles are sieved and doped diamond particles with an average particle size of 0.5 mm are selected.

[0328] Preparation Example 51

[0329] The method of synthesizing doped diamond particles using a high temperature and high pressure method includes the following steps:

[0330] Graphite is used as a carbon source, and high-purity boron powder is used as a source of the doping element B. The graphite and boron powder are uniformly mixed while controlling the mass ratio of the boron element to the carbon element to be 20%. Under the condition of Fe-Ni as a catalyst, the reaction temperature is controlled to be 1800°C, the reaction pressure is controlled to be 10GPa, and the reaction is carried out for 4 minutes to produce octahedral doped diamond particles. The above-mentioned doped diamond particles are sieved and doped diamond particles with an average particle size of 0.5 mm are selected.

[0331] Examples 55 to 57

[0332] Examples 55 to 57 respectively provide a diamond electrode prepared using the above-mentioned doped diamond particles.

[0333] 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.

[0334] Table 27 Selection of conductive diamond particles in Examples 55 to 57

[0335] Selected conductive diamond particles Example 55 Preparation Example 49 Example 56 Preparation Example 50 Example 57 Preparation Example 51

[0336] The electrode performance of the diamond electrodes provided in Examples 55 to 57 was tested, and the test results are recorded in Table 28.

[0337] Table 28 Summary of test results of Examples 55 to 57

[0338] Resistivity / mΩ·cm <![CDATA[Specific surface area / cm -1 > Aqueous solution potential window / V Example 55 97.4 31.2 3.6 Example 56 23.8 33.0 3.6 Example 57 6.4 32.7 3.5

[0339] 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.

[0340] 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.

[0341] Examples 58 to 63

[0342] 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 by 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 the same as those in Example 1.

[0343] Table 29 Selection of conductive diamond particles in Examples 58 to 63

[0344] Selected conductive diamond particles Example 58 Preparation Example 28, Preparation Example 47 Example 59 Preparation Example 32, Preparation Example 49 Example 60 Preparation Example 48, Preparation Example 49 Example 61 Preparation Example 3, Preparation Example 44, Preparation Example 49 Example 62 Preparation Example 13, Preparation Example 45, Preparation Example 50 Example 63 Preparation Example 19, Preparation Example 46, Preparation Example 51

[0345] The electrode performance of the diamond electrodes provided in Examples 58 to 63 was tested, and the test results are recorded in Table 30.

[0346] Table 30 Summary of test results of Examples 58 to 63

[0347] <![CDATA[Specific surface area / cm -1 > Aqueous solution potential window / V Example 58 6120.4 3.3 Example 59 4176.7 3.3 Example 60 4023.4 3.4 Example 61 43.9 3.6 Example 62 67.2 3.6 Example 63 36.5 3.2

[0348] 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.

[0349] It should be noted that the resistivity of the diamond electrodes provided in Examples 58-63 was not measured. This is because, in Examples 58-63, the deposited doped diamond coating and the doped diamond particles themselves are the conductive materials. Adding conductive diamond particles 2 does not affect the sheet resistance of the doped diamond coating or the resistivity of the doped diamond particles. Furthermore, Table 29 does not specify the selection and combination of conductive diamond particles 2. In other words, any combination of two or more conductive diamond particles 2 from Preparation Examples 1-51 can be used to prepare diamond electrodes.

[0350] 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 Examples 64 to 69.

[0351] Preparation Example 52

[0352] 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 when the thickness of the deposited coating I of micron-sized doped diamond grains is 5 μm, the deposition is stopped; the remaining steps, conditions and parameters are the same as those in Preparation Example 3.

[0353] Preparation Example 53

[0354] 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 when the thickness of the deposited coating I of micron-sized doped diamond grains is 5 μm, the deposition is stopped; the remaining steps, conditions and parameters are the same as those in Preparation Example 3.

[0355] Preparation Example 54

[0356] 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 when the thickness of the deposited coating I of micron-sized doped diamond grains is 5 μm, the deposition is stopped; the remaining steps, conditions and parameters are the same as those in Preparation Example 3.

[0357] Preparation Example 55

[0358] 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 when the thickness of the deposited coating I of micron-sized doped diamond grains is 5 μm, the deposition is stopped; the remaining steps, conditions and parameters are the same as those in Preparation Example 3.

[0359] Preparation Example 56

[0360] 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 when the thickness of the deposited coating I of micron-sized doped diamond grains is 5 μm, the deposition is stopped; the remaining steps, conditions and parameters are the same as those in Preparation Example 3.

[0361] Preparation Example 57

[0362] 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 when the thickness of the deposited coating I of micron-sized doped diamond grains is 5 μm, the deposition is stopped; the remaining steps, conditions and parameters are the same as those in Preparation Example 3.

[0363] Examples 64 to 69

[0364] Examples 64 to 69 respectively provide a diamond electrode prepared using the above-mentioned conductive diamond particles 2.

[0365] 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.

[0366] Table 31 Selection of conductive diamond particles in Examples 64 to 69

[0367] Selected conductive diamond particles Example 64 Preparation Example 52 Example 65 Preparation Example 53 Example 66 Preparation Example 54 Example 67 Preparation Example 55 Example 68 Preparation Example 56 Example 69 Preparation Example 57

[0368] The electrode performance of the diamond electrodes provided in Examples 64 to 69 was tested, and the test results are recorded in Table 32.

[0369] Table 32 Summary of test results of Examples 64 to 69

[0370] Resistivity / mΩ·cm <![CDATA[Specific surface area / cm -1 > Aqueous solution potential window / V Example 64 8.1 4.2 3.6 Example 65 8.7 48.0 3.6 Example 66 8.2 6.2 3.6 Example 67 8.3 4.5 3.6 Example 68 8.5 1.5 3.6 Example 69 8.7 0.8 3.6

[0371] 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 first increases and then decreases with the particle size of the conductive diamond particles 2. Specifically, although the particle size of the conductive diamond particles 2 in the diamond electrode provided in Example 64 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 In this case, 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.

[0372] In order to further verify the feasibility of preparing diamond electrodes using a basket 1 made of other materials, this application also provides Examples 70 to 71.

[0373] Example 70

[0374] Based on Example 1, the difference between this embodiment and Example 1 is that the material of the enclosure basket 1 used in this embodiment is silicon carbide; at this time, the enclosure basket 1 can be a rigid enclosure basket; the remaining steps, conditions and parameters are the same as those in Example 1.

[0375] Example 71

[0376] Based on Example 1, the difference between this embodiment and Example 1 is that the material of the surrounding basket 1 used in this embodiment is metal titanium, and a layer of diamond coating is deposited on the surface of the surrounding basket 1 made of metal titanium.

[0377] The electrode performance of the diamond electrodes provided in Examples 70 to 71 was tested, and the test results are recorded in Table 33.

[0378] Table 33 Summary of test results of Examples 70 to 71

[0379] Resistivity / mΩ·cm <![CDATA[Specific surface area / cm -1 > Aqueous solution potential window / V Example 70 45.2 45.1 3.4 Example 71 45.2 45.2 3.4

[0380] Referring to Table 33, it can be seen from the results in 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.

[0381] In summary, the diamond electrode provided in this application has good advantages.

[0382] Furthermore, in order to verify that the diamond electrode provided in this application can be normally used in a working environment and can realize the internal cleaning of the diamond electrode and reuse after cleaning, this application also provides application examples 1 to 2 for different application scenarios, and application examples 1 to 2 respectively provide two cleaning modes for diamond electrodes.

[0383] Application Example 1

[0384] This application example uses the diamond electrode provided in Example 1 to verify its feasibility.

[0385] The diamond electrode provided in Example 1 was applied to wastewater purification. The electrode potential window (CV curve) of the diamond electrode was detected. When the peak current of the CV curve increased or decreased by 20%, the diamond electrode was 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 self-cleaning of the diamond electrode surface.

[0386] 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 3.4 V. Comparing this with the electrode performance test results of Example 1 in Table 3, it can be seen that the resistivity of the cleaned diamond electrode increased by 7.7%, the effective active area of ​​the electrode decreased by 4.2%, and the aqueous solution potential window remained unchanged. This shows that the diamond electrode provided by this application can also perform good surface self-cleaning.

[0387] Application Example 2

[0388] This application example uses the diamond electrode provided in Example 1 to verify its feasibility.

[0389] The diamond electrode provided in Example 1 was applied to carbon dioxide degradation. When the pores between the conductive diamond particles 2 were blocked, the diamond electrode was cleaned using the cleaning method unique to the present application, specifically:

[0390] The conductive diamond particles 2 compacted in the diamond electrode are disassembled and taken out of the surrounding basket 1. The conductive diamond particles 2 are 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 to complete the cleaning of the diamond electrode.

[0391] 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 3.4 V. Compared with the electrode performance test results of Example 1 recorded in Table 3, it can be seen that the changes in the resistivity, specific surface area, and aqueous solution potential window of the cleaned diamond electrode do not exceed 2%. This shows that the diamond electrode provided by this application can be cleaned using a unique cleaning method, and has a better effect than self-cleaning the surface of the diamond electrode.

[0392] The above are all preferred embodiments of the present application, and are not intended to limit the scope of protection of the present application. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the scope of protection of the present application.

Claims

1. A diamond electrode, characterized in that: The invention comprises a basket and conductive diamond particles, wherein the basket is provided with holes to form a mesh basket, wherein the aperture of the holes is smaller than the particle size of the conductive diamond particles; the conductive diamond particles are placed in the basket, and the conductive diamond particles include at least one of heterogeneous material substrate particles and diamond substrate particles, and the surfaces of the heterogeneous material substrate particles and the diamond substrate particles are both deposited with a doped diamond coating, wherein the doped diamond coating includes a first coating and a second coating, wherein the first coating is a coating II of micron-sized doped diamond grains, and the second coating is a coating II of nanometer-sized 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; the resistivity of the basket is ρ 围篮 and the resistivity ρ of the conductive diamond particles 导电金刚石颗粒 Satisfies the following relationship: 围篮 ≥ρ 导电金刚石颗粒 Depositing the doped diamond coating on the surface of the heterogeneous material substrate particles or the diamond substrate particles using a 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. Suspend the introduction of methane and B to form a H2 / Ar etching atmosphere; in the H2 / Ar etching atmosphere: the hydrogen flow rate is 6-10 SLM, the argon flow rate is 2.5-5 SLM; the etching temperature is 750-1050°C, the etching pressure is 2.8-4.5 kPa, and the etching time is 5-30 min; 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 7-9 SLM, the argon flow rate is 2.5-5 SLM, the methane flow rate is CH4 / H2=4-8%, and the B doping amount is B / C=3000-12000 ppm; the deposition temperature is 700-820°C, the deposition pressure is 2.5-4.5 kPa, and the deposition time is 5-15 min; A4, suspend the introduction of methane and B, form an 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, wherein the first coating is a coating II of micron-sized doped diamond grains, and the second coating is a coating II of nano-sized doped diamond grains, and the second coating is deposited on the first coating; The surface of the first coating layer has micro-pits II, and the second coating layer has a porous structure II.

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

3. A method for preparing a diamond electrode according to claim 1, characterized in that: The steps include: S1. Prepare a basket, wherein the basket is made of polyethylene resin; prepare conductive diamond particles: prepare at least one of heterogeneous material substrate particles with a doped diamond coating deposited on the surface and diamond substrate particles with a doped diamond coating deposited on the surface, so that the surfaces of the heterogeneous material substrate particles and the diamond substrate particles are deposited with a doped diamond coating, the doped diamond coating comprising a first coating and a second coating, the first coating being a coating II of micron-sized doped diamond grains, and the second coating being a coating II of nanometer-sized doped diamond grains, the second coating being deposited on the first coating; The surface of the first coating layer has micro-pits II, and the second coating layer has a porous structure II; S2, placing the conductive diamond particles in the basket, wherein the basket defines the shape of the conductive diamond particles to form a diamond electrode; and controlling the resistivity ρ of the basket. 围篮 and the resistivity ρ of the conductive diamond particles 导电金刚石颗粒 Satisfies the following relationship: 围篮 ≥ρ 导电金刚石颗粒 .

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