Diamond electrode and preparation method thereof

Abstract

The invention relates to the technical field of electrode preparation, in particular to a diamond electrode and a preparation method thereof. The diamond electrode comprises a porous consolidation block formed by consolidating conductive diamond particles; the particle size of the conductive diamond particles is 0.3-10 mm; the conductive diamond particles comprise diamond particles or diamond particles with diamond coatings deposited on the surfaces; the diamond grains or the diamond coating are electrically conductive by doping elements. On the basis, a nano-diamond porous membrane is deposited on the surface of the porous consolidation block, and the thickness of the nano-diamond porous membrane is 1-20 microns. In addition, the invention further provides a preparation method of the diamond electrode. The diamond electrode provided by the invention has a high specific surface area, and can control pores in the electrode and enable the pores to be exposed in a working environment.

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] Diamond is a material with unique physical and chemical properties. It is not easy to react with acids, bases and salts, and has good chemical stability. In recent years, researchers have applied it to fields such as electrochemical degradation of organic wastewater. Diamond can be turned into a semiconductor or a conductor with metallic properties by boron doping. Compared with traditional electrodes, boron-doped diamond electrodes have many advantages such as wide electrochemical window, good electrochemical stability, good mechanical properties, strong corrosion resistance, and good conductivity. Especially for difficult-to-degrade organic pollutants that are difficult to remove by biochemical treatment methods, the use of boron-doped diamond electrodes can often completely mineralize the difficult-to-degrade organic pollutants, thereby achieving the removal of difficult-to-degrade organic pollutants.

[0003] However, most of the existing boron-doped diamond electrodes are planar electrodes with low specific surface area, which makes the electrodes have defects such as small active area, low spatial yield of strong oxidizing groups-hydroxyl radicals, slow mass transfer rate, etc., and at the same time, it also restricts the electrocatalytic performance of the existing boron-doped diamond electrodes. In addition, the pore size inside the existing diamond electrodes is small, and most of them are non-penetrating pores, which are easily blocked by debris or reaction products, resulting in the above pores not being exposed to the working environment, making the above diamond electrodes difficult to apply to different working environments and having low working efficiency.

[0004] Therefore, there is an urgent need for a diamond electrode with a high specific surface area, which can control the internal pores of the electrode and expose the pores to the working environment. Summary of the invention

[0005] The present application provides a diamond electrode and a preparation method thereof. The diamond electrode has a high specific surface area and can control the pores inside the electrode and expose the pores to the working environment.

[0006] In a first aspect, the present application provides a diamond electrode, which adopts the following technical solution:

[0007] A diamond electrode, comprising a porous consolidated block formed by consolidating conductive diamond particles; the conductive diamond particles have a particle size of 0.3-10 mm;

[0008] The conductive diamond particles include diamond particles or diamond particles with diamond coatings deposited on the surface;

[0009] The diamond grains or the diamond coating are made conductive by doping elements.

[0010] The main structure of the diamond electrode provided by the present application is a porous consolidation block formed by consolidating diamond particles or diamond particles with diamond coatings deposited on the surface. The setting of the porous consolidation block makes the diamond electrode provided by the present application a three-dimensional electrode, which can increase the active specific surface area of ​​the diamond electrode itself. The diamond electrode of the present application has diamond particles with diamond coatings deposited on the surface or a consolidation layer deposited between the diamond particles, so that the diamond particles are consolidated together. The diamond particles in the consolidation block or the diamond particles with diamond coatings deposited on the surface have large through pores, and the pores are fully exposed to the working environment of the diamond electrode, so that the diamond electrode provided by the present application becomes a three-dimensional electrode, and the treated liquid can flow freely and transfer mass in the pores. The setting of the pores greatly increases the active specific surface area of ​​the diamond electrode, improves the working efficiency of the diamond electrode, and can also achieve the purpose of controlling the internal pores of the diamond electrode by changing the size of the above-mentioned diamond particles and the thickness of the coating.

[0011] Optionally, the diamond particles or the diamond particles with diamond coating deposited on the surface have a particle size of 1-5 mm.

[0012] In a specific embodiment, the diamond particles or the diamond particles with diamond coating deposited on the surface have a particle size of 0.3 mm, 1 mm, 3 mm, 5 mm, 8 mm, or 10 mm.

[0013] In some specific embodiments, the diamond particles or the diamond particles with diamond coating deposited on the surface have a particle size of 0.3-1mm, 0.3-3mm, 0.3-5mm, 0.3-8mm, 1-3mm, 1-5mm, 1-8mm, 1-10mm, 3-5mm, 3-8mm, 3-10mm, 5-8mm, 5-10mm, 8-10mm.

[0014] Optionally, the thickness of the diamond coating is 1-20 μm, and the particle size of the diamond grains is 0.5-10 μm; the diamond particles with the diamond coating deposited on the surface form the porous consolidated block through a consolidation layer, the thickness of the consolidation layer is 2-20 μm, and the particle size of the diamond grains is 0.5-15 μm; the sum of the thickness of the diamond coating and the consolidation layer is ≥5 μm.

[0015] Optionally, the diamond coating has a thickness of 5-15 μm.

[0016] In a specific embodiment, the thickness of the diamond coating is 1 μm, 5 μm, 10 μm, 15 μm, or 20 μm.

[0017] In some specific embodiments, the diamond coating has a thickness of 1-5 μm, 1-10 μm, 1-15 μm, 5-10 μm, 5-15 μm, 5-20 μm, 10-15 μm, 10-20 μm, or 15-20 μm.

[0018] Optionally, the consolidation layer has a thickness of 5-15 μm.

[0019] In a specific embodiment, the thickness of the consolidation layer is 2 μm, 5 μm, 10 μm, 15 μm, or 20 μm.

[0020] In some specific embodiments, the thickness of the consolidation layer is 2-5 μm, 2-10 μm, 2-15 μm, 5-10 μm, 5-15 μm, 5-20 μm, 10-15 μm, 10-20 μm, or 15-20 μm.

[0021] The sum of the thickness of the diamond coating and the consolidation layer is ≥5 μm.

[0022] In a specific embodiment, the sum of the thickness of the diamond coating and the consolidation layer is 5 μm, 10 μm, 15 μm, 20 μm, 25 μm, 30 μm, or 35 μm.

[0023] In some specific embodiments, the sum of the thicknesses of the diamond coating and the consolidation layer is 5-10 μm, 5-15 μm, 5-20 μm, 5-25 μm, 5-35 μm, 10-15 μm, 10-20 μm, 10-25 μm, 10-30 μm, 10-35 μm, 15-20 μm, 15-30 μm, 15-35 μm, 20-25 μm, 20-30 μm, 20-35 μm, 25-30 μm, 25-35 μm, 30-35 μm.

[0024] Optionally, the diamond particles with diamond coating deposited on the surface have substrate particles inside; the material of the substrate particles is selected from diamond, silicon carbide, silicon dioxide and silicon.

[0025] In a specific embodiment, the material of the substrate particles may be diamond.

[0026] In a specific embodiment, the material of the substrate particles may be silicon carbide.

[0027] In a specific embodiment, the material of the substrate particles may be silicon dioxide.

[0028] In a specific embodiment, the material of the substrate particles may be silicon.

[0029] Optionally, a nano-diamond porous film is also deposited on the surface of the porous consolidated block; the nano-diamond porous film is made conductive by doping elements.

[0030] Optionally, the thickness of the nano-diamond porous film is 1-20 μm, and the diameter of the diamond grains is 10-800 nm.

[0031] Optionally, the thickness of the nano-diamond porous film is 2-12 μm, and the diameter of the diamond grains is 35 nm-500 nm.

[0032] The outer surface of the diamond electrode of the present application is also provided with a nano-diamond porous membrane, which can form a porous structure on the electrode surface. The pore size in the nano-diamond porous membrane is nanoscale. Although it is a non-penetrating pore, it is an open pore that connects the interior of the consolidated block with the outside world. Ions in the liquid can transfer mass and exchange charges in the pores by diffusion, further increasing the active specific surface area of ​​the diamond electrode.

[0033] The doping element in the present application may be any element in the periodic table that can make diamond conductive through doping.

[0034] Optionally, the doping element is selected from any one of B, P, S, Li and Ba.

[0035] In a specific embodiment, the doping element may be B.

[0036] In a specific embodiment, the doping element may be P.

[0037] In a specific embodiment, the doping element may be S.

[0038] In a specific embodiment, the doping element may be Li.

[0039] In a specific embodiment, the doping element may be Ba.

[0040] In a second aspect, the present application provides a method for preparing the above-mentioned diamond electrode, using the following technical solution:

[0041] A method for preparing a diamond electrode specifically comprises the following steps: stacking prepared conductive diamond particles and continuously depositing a consolidation layer on the surface, thereby consolidating the conductive diamond particles to obtain a porous consolidation block.

[0042] Furthermore, the method also includes the following steps: depositing a nano-diamond porous membrane on the surface of the porous consolidated block, specifically: etching the surface of the porous consolidated block to form etch pits; then using chemical vapor deposition and etching processes alternately to deposit and etch to prepare the nano-diamond porous membrane.

[0043] In a specific embodiment, a method for preparing a diamond electrode comprises the following steps:

[0044] (1) depositing a doped diamond coating on the surface of a substrate particle to obtain a diamond particle having a diamond coating deposited on the surface;

[0045] (2) stacking the diamond particles with diamond coating deposited on the surface obtained in step (1) and further depositing a diamond-doped consolidation layer on the surface, thereby consolidating the diamond particles with diamond coating deposited on the surface to obtain a porous consolidation block;

[0046] (3) depositing a nano-diamond porous membrane on the surface of the porous consolidated block obtained in step (2), specifically: etching the surface of the porous consolidated block to form etch pits; then depositing and etching by alternating chemical vapor deposition and etching processes to prepare the nano-diamond porous membrane.

[0047] When the present application uses diamond particles with diamond coatings deposited on the surface to prepare diamond electrodes, the deposition is performed using chemical vapor deposition.

[0048] When the present application uses diamond particles with diamond coatings deposited on the surface to prepare diamond electrodes, the diamond particles with diamond coatings deposited on the surface are first prepared, and then a diamond-doped consolidation layer is deposited between the diamond particles with diamond coatings deposited on the surface. The diamond particles are consolidated into blocks by a two-step deposition method, and then a nano-diamond porous film is deposited on the surface of the consolidated block to complete the preparation of the electrode. The entire preparation process is simple and easy to operate.

[0049] In summary, the present application includes at least one of the following beneficial technical effects:

[0050] 1. The main structure of the diamond electrode provided in the present application is a porous consolidated block formed by consolidating diamond particles or diamond particles with diamond coating deposited on the surface. The setting of the porous consolidated block makes the diamond electrode provided in the present application a three-dimensional electrode, which can increase the specific surface area of ​​the diamond electrode itself.

[0051] 2. The diamond electrode of the present application has a consolidation layer deposited between diamond particles or diamond particles, so that the diamond particles are consolidated together. The diamond particles or diamond particles in the consolidation block have large through pores, and the pores are fully exposed to the working environment of the diamond electrode, so that the diamond electrode provided by the present application becomes a three-dimensional electrode, and the treated liquid can flow freely and transfer mass in the pores. Such pore setting greatly increases the active specific surface area of ​​the diamond electrode and improves the working efficiency of the diamond electrode. The purpose of controlling the internal pores of the diamond electrode can also be achieved by changing the size of the above-mentioned diamond particles and the thickness of the coating to meet different application requirements.

[0052] 3. The outer surface of the diamond electrode of the present application is also provided with a nano-diamond porous membrane, which can form a porous structure on the electrode surface. The pore size in the nano-diamond porous membrane is nanoscale. Although it is a non-penetrating pore, it is an open pore that connects the interior of the consolidated block with the outside world. The ions in the liquid can diffuse in the pores for mass transfer and charge exchange, further increasing the active specific surface area of ​​the diamond electrode.

[0053] 4. The present application first prepares diamond particles with a diamond coating deposited on the surface, and then deposits a diamond-doped consolidation layer between the diamond particles with the diamond coating deposited on the surface, consolidates the diamond particles into blocks using a two-step deposition method, and then deposits a nano-diamond porous film on the surface of the consolidated block to complete the preparation of the electrode. The entire preparation process is simple and easy to operate. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 This is an example 1 of diamond particles with a diamond coating deposited on the surface (the shape of the substrate particles is a spherical particle).

[0055] Figure 2 This is Example 2 of diamond particles with diamond coating deposited on the surface (the shape of the substrate particles is a polyhedral particle).

[0056] Figure 3 It is a structural schematic diagram of the consolidation tooling.

[0057] Figure 4 Schematic diagram of the structure of the porous consolidated block prepared in Example 1.

[0058] Figure 5 This is the SEM morphology of the surface of the porous consolidated block in Example 1.

[0059] Figure 6 This is the SEM morphology of the nanodiamond porous membrane in Example 17.

[0060] Explanation of the reference numerals: 1. Diamond particles; 11. Substrate particles; 12. Diamond coating; 2. Consolidation tooling; 21. Size limiting ring; 22. Limiting grid; 3. Porous consolidation block. DETAILED DESCRIPTION

[0061] Before describing the embodiments of the present application in detail, it should be understood that the terms used herein are only used for the purpose of describing specific embodiments. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by ordinary technicians in the field to which the terms belong.

[0062] The present application provides a diamond electrode, comprising a porous consolidation block formed by consolidating conductive diamond particles; the particle size of the conductive diamond particles is 0.3-10 mm; the conductive diamond particles include diamond particles or diamond particles with a diamond coating deposited on the surface; the diamond particles or the diamond coating are made conductive by doping elements. Preferably, the particle size of the diamond particles or the diamond particles with a diamond coating deposited on the surface is 1-5 mm.

[0063] Furthermore, the thickness of the diamond coating is 1-20 μm, and the particle size of the diamond grains is 0.5-10 μm; the diamond particles with the diamond coating deposited on the surface form a porous consolidated block through a consolidation layer, the thickness of the consolidation layer is 2-20 μm, and the particle size of the diamond grains is 0.5-15 μm; the sum of the thickness of the diamond coating and the consolidation layer is ≥5 μm. The diamond particles with the diamond coating deposited on the surface are substrate particles, and the material of the substrate particles is selected from diamond, silicon carbide, silicon dioxide and silicon.

[0064] On the basis of the above, a nano-diamond porous film is also deposited on the surface of the porous consolidated block; the nano-diamond porous film is made conductive by doping elements. The thickness of the nano-diamond porous film is 1-20 μm, and the diameter of the diamond grains is 10-800 nm.

[0065] In the present application, the doping element is selected from any one of B, P, S, Li and Ba.

[0066] The present application also provides a method for preparing a diamond electrode. The preparation method specifically comprises the following steps:

[0067] (1) depositing a doped diamond coating on the surface of a substrate particle to obtain a diamond particle having a diamond coating deposited on the surface;

[0068] (2) stacking the diamond particles with diamond coating deposited on the surface obtained in step (1) and further depositing a diamond-doped consolidation layer on the surface, thereby consolidating the diamond particles with diamond coating deposited on the surface to obtain a porous consolidation block;

[0069] (3) depositing a nano-diamond porous membrane on the surface of the porous consolidated block obtained in step (2), specifically: etching the surface of the porous consolidated block to form etch pits; then depositing and etching by alternating chemical vapor deposition and etching processes to prepare the nano-diamond porous membrane.

[0070] When the applicant was improving the electrode material, he found that most of the existing electrodes were in the form of boron-doped diamond, which turned diamond into a semiconductor or a conductor with metallic properties, thereby obtaining a diamond electrode. However, most of the diamond electrodes in the related art adopt a planar design, and their specific surface area is relatively low. The low specific surface area restricts the performance of the diamond electrodes in the related art. In addition, even if the existing diamond electrodes are three-dimensional electrodes, the interior of the diamond electrodes in the related art cannot be fully exposed to the working environment of the diamond electrodes due to their own structural airtightness. In this case, the specific surface area of ​​the diamond electrode can only be increased by increasing the ratio between the outer surface of the diamond electrode and the size of the diamond electrode. However, the use of the above method to increase the specific surface area of ​​the diamond electrode is relatively limited, and it is impossible to prepare a diamond electrode with a high specific surface area.

[0071] Therefore, the applicant sets the diamond electrode into an electrode block composed of multiple conductive diamond particles, starting from the internal pores of the diamond electrode. The conductive diamond particles are consolidated by a consolidation layer doped with diamond, and large through pores are formed between the diamond particles. The pores are fully exposed to the working environment of the diamond electrode, and the processed liquid can flow freely and transfer mass in the pores. The diamond electrode provided by the present application is a porous three-dimensional diamond electrode with an extremely high specific surface area.

[0072] The diamond electrode provided in this application can achieve an increase in specific surface area from two aspects:

[0073] In the first aspect, the diamond electrode provided by the present application is prepared by consolidating multiple conductive diamond particles, so that the diamond electrode provided by the present application forms a three-dimensional electrode, which can increase the specific surface area of ​​the diamond electrode itself;

[0074] Secondly, after consolidation, larger through-pores are formed between the conductive diamond particles. The pores are fully exposed to the working environment of the diamond electrode. The treated liquid can flow and transfer mass freely in the pores, thereby further increasing the active specific surface area of ​​the diamond electrode.

[0075] In addition, a nano-diamond porous membrane is also provided on the surface of the diamond electrode provided in the present application, and the interior of the consolidated block is connected to the outside, so that ions in the liquid can transfer mass and exchange charges in the pores by diffusion, thereby further improving the active specific surface area of ​​the diamond electrode provided in the present application.

[0076] In order to make the purpose, technical solutions and advantages of this application clearer, the technical solutions in the embodiments of this application are clearly and completely described below in conjunction with the accompanying drawings. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without making creative work are within the scope of protection of this application.

[0077] The present application is further described in detail below in conjunction with embodiments, drawings, comparative examples and performance test results.

[0078] The present application may adopt chemical vapor deposition, and the deposition parameters may be adjusted as needed. The selection of the deposition method and the adjustment of the deposition parameters will not have much impact on the preparation of the diamond electrode of the present application.

[0079] In the present application, the shape of the substrate particles can be arbitrary. Figure 1 As shown, the shape of the substrate particles 11 can be spherical particles; Figure 2 As shown, the shape of the substrate particles 11 can be polyhedral particles.

[0080] In the following examples, the doping element used is B. The boron source used is selected from diborane, borax, elemental boron, trimethyl boron, trimethyl borate, and the like.

[0081] In the following embodiments, Figure 2 Taking the middle substrate particle 11 as a polyhedral particle as an example, the technical solution of the present application is explained.

[0082] Example 1

[0083] The present application provides a diamond electrode.

[0084] The method for preparing the diamond electrode specifically comprises the following steps:

[0085] (1) Preparation of diamond particles with diamond coating deposited on the surface

[0086] A. Pretreatment of substrate particles

[0087] The substrate particles were cleaned with anhydrous ethanol; the cleaned substrate particles were then ultrasonically treated with a diamond powder suspension for 30 minutes, and diamond seed crystals were pre-placed on the surface of the substrate particles; the substrate particles were cleaned with anhydrous ethanol and deionized water in turn, and then dried. In the diamond powder suspension, the mass fraction of diamond powder with a particle size of 5μm was 50%, the mass fraction of diamond powder with a particle size of 20μm was 50%, and the solvent was anhydrous ethanol.

[0088] B. Figure 2 As shown, a diamond coating 12 is deposited on the surface of a substrate particle 11 with a pre-set diamond seed crystal to obtain a diamond particle 1 with a diamond coating deposited on the surface. The particle size of the diamond particle 1 with a diamond coating deposited on the surface, the material of the substrate particle 11 and the thickness of the diamond coating 12 are shown in Table 1.

[0089] The deposition process of diamond coating is as follows:

[0090] Using CH 4 / H 2 / Ar deposition atmosphere, set the methane flow rate to 120sccm, the hydrogen flow rate to 8SLM, and the argon flow rate to 3SLM; the deposition temperature is 830℃, the deposition pressure is 3kPa; the B / C ratio in the atmosphere is 5000ppm.

[0091] (2) Consolidation of diamond particles

[0092] refer to Figure 3 In this embodiment, a specific consolidation tool 2 is used. The consolidation tool 2 includes a size limiting ring 21, and a limiting grid 22 is provided at both sides of the opening of the size limiting ring 21. A consolidation cavity is formed between the limiting grid 22 and the size limiting ring 21, and the consolidation cavity is used to accommodate the diamond particles 1 with a diamond coating deposited on the surface.

[0093] The diamond particles 1 with diamond coating deposited on the surface are filled into the consolidation cavity, and a consolidation layer doped with diamond is further deposited on the surface, so that the diamond particles 1 with diamond coating deposited on the surface are consolidated, and the consolidation tool 2 is removed to obtain a porous consolidation block 3, such as Figure 4 shown.

[0094] The deposition process of the consolidation layer is as follows:

[0095] Using CH 4 / H 2 / Ar deposition atmosphere, set the methane flow rate to 120sccm, the hydrogen flow rate to 8SLM, and the argon flow rate to 3SLM; the deposition temperature is 830℃, the deposition pressure is 3kPa; the B / C ratio in the atmosphere is 5000ppm.

[0096] In this embodiment, the SEM morphology of the surface of the porous consolidated block is as follows: Figure 5 As shown. Figure 5 It can be seen that the crystal shape of diamond grains on the surface of diamond particles is complete.

[0097] Embodiment 2-6

[0098] Embodiments 2-6 provide a diamond electrode respectively. The difference between the above embodiment and embodiment 1 is that the particle sizes of the diamond particles with diamond coating deposited on the surface are different, as shown in Table 1. The remaining parameters and steps are consistent with those in embodiment 1.

[0099] Embodiment 7-13

[0100] Examples 7-13 provide a diamond electrode respectively. The difference between the above examples and Example 4 is that the coating thickness of the diamond particles is different, as shown in Table 1. The remaining parameters and steps are consistent with those of Example 4.

[0101] Examples 14-16

[0102] Embodiments 14-16 provide a diamond electrode respectively. The difference between the above embodiment and embodiment 4 is that the material of the substrate particles is different, as shown in Table 1. The remaining parameters and steps are consistent with those of embodiment 4.

[0103] Table 1 Partial parameters of diamond electrodes provided in the embodiments and comparative examples

[0104]

[0105]

[0106] Embodiment 17

[0107] Embodiment 17 provides a diamond electrode. The difference between this embodiment and embodiment 4 is that a nano-diamond porous film is also deposited on the surface of the porous consolidated block.

[0108] The method for preparing the diamond electrode specifically comprises the following steps:

[0109] (1) Preparation of diamond particles with diamond coating deposited on the surface: Same as Example 1.

[0110] (2) Consolidation of diamond particles with diamond coating deposited on the surface: Same as Example 1.

[0111] (3) Deposition of nanodiamond porous film:

[0112] A nano-diamond porous film is deposited on the surface of the porous consolidated block obtained in step (2). Specifically, etching is performed on the surface of the porous consolidated block to form an etch pit; then chemical vapor deposition diamond and etching processes are alternately performed to deposit and etch to prepare a porous film. Chemical vapor deposition is performed for 10 minutes, and plasma etching is performed once. The etching time is one third of the chemical vapor deposition time. The thickness of the porous film is shown in Table 1.

[0113] The etching process is as follows: using H 2 The etching was performed by hydrogen-argon plasma in a / Ar etching atmosphere.

[0114] The etching parameters are as follows: 2 In the O / Ar etching atmosphere, the hydrogen flow rate is 8 SLM, and the argon flow rate is 3 SLM; the etching temperature is 950°C, and the etching pressure is 3.5 kPa.

[0115] The deposition process of nanodiamond porous film is as follows:

[0116] Using CH 4 / H 2 / Ar deposition atmosphere, set the methane flow rate to 480sccm, the hydrogen flow rate to 8slm, the argon flow rate to 3slm, the deposition temperature to 780℃, and the deposition pressure to 3.0kPa; the B / C ratio in the atmosphere was 5000ppm; after 10min of deposition, the introduction of methane and B was suspended to form H 2 / Ar etching atmosphere, hydrogen-argon plasma etching, the etching time is 1 / 3 of the deposition time; after the etching is completed, continue in H 2 Methane is introduced into the Ar / Ar etching atmosphere, and B is introduced to alternately deposit and etch to form a nano-diamond porous film.

[0117] In this embodiment, the SEM morphology of the chemical vapor deposition nanodiamond porous film on the surface of the porous consolidated block is as follows: Figure 6 As shown. Figure 6 It can be seen that the nanodiamond porous membrane has an obvious porous structure.

[0118] Examples 18-23

[0119] Examples 18-23 provide a diamond electrode respectively. The difference between the above example and Example 17 is that the thickness of the nano-diamond porous membrane is different, as shown in Table 1. The remaining parameters and steps are consistent with Example 4.

[0120] Embodiment 24

[0121] This embodiment provides a diamond electrode. The difference between the above embodiment and embodiment 4 is that diamond particles are consolidated into a porous consolidated block, as shown in Table 1. The remaining parameters and steps are consistent with those of embodiment 4.

[0122] Embodiment 25

[0123] This embodiment provides a diamond electrode. The difference between the above embodiment and embodiment 19 is that the diamond particles are consolidated into a porous consolidated block, as shown in Table 1. The remaining parameters and steps are consistent with those of embodiment 4.

[0124] Comparative Example

[0125] Comparative Example 1-2

[0126] Comparative Examples 1-2 provide a diamond electrode respectively. The difference between the above embodiment and embodiment 4 is that the particle size of the diamond particles is different, as shown in Table 1. The remaining parameters and steps are consistent with those of embodiment 4.

[0127] Comparative Example 3

[0128] Comparative Example 3 provides a diamond electrode.

[0129] Taking into account the production cost and time cost, based on Example 4, the difference between this comparative example and Example 4 is that in step (2), when depositing the consolidation layer, the consolidation layer is grown to the point where the pores on the surface of the deposited diamond particles are completely filled, and the deposition is stopped to obtain a consolidation block. The remaining parameters and steps are consistent with Example 4.

[0130] Performance test results

[0131] (I) Active specific surface area detection

[0132] The active specific surface areas of the diamond electrodes prepared in the above examples and comparative examples were tested respectively. The test results are shown in Table 1.

[0133] The detection method is as follows: The active specific surface area of ​​the diamond electrode is expressed as the effective active area per unit volume of the electrode, which is calculated using the chronocoulometry method. The test solution is 0.1M KCl / 0.1mM K 3 [Fe(CN) 6 ].

[0134] (II) Potential Window of Aqueous Solution

[0135] The aqueous solution potential windows of the diamond electrodes prepared in the above examples and comparative examples were tested respectively. The test results are shown in Table 1.

[0136] The detection method is as follows: the current-cyclic voltammetry scanning method is used for measurement, the working electrode is a diamond electrode, the auxiliary electrode is a Pt electrode, the reference electrode is a saturated calomel electrode, and the solution is 0.2M Na 2 SO 4 , the cyclic scanning rate is 0.1V / s.

[0137] As can be seen from Table 1, the smaller the particle size of the conductive diamond particles, the larger the active specific surface area. However, when the particle size is too small, due to the small pores between the particles, the pores between some particles will be blocked when the consolidation layer is deposited, so the active specific surface area of ​​the prepared diamond electrode is reduced. At the same time, when the particle size of the conductive diamond particles is the same, the thicker the consolidation layer, the smaller the active specific surface area. In addition, when the particle size of the conductive diamond particles is the same and different particle substrate materials are used, the active specific surface area will not change greatly due to different substrate materials. Based on the above, the technical solution of the present application can effectively improve the active specific surface area of ​​the prepared diamond electrode.

[0138] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present application, rather than to limit it. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A diamond electrode, characterized in that: It comprises a porous consolidated block formed by consolidating conductive diamond particles; the particle size of the conductive diamond particles is 0.3-10 mm; The conductive diamond particles include diamond particles or diamond particles with diamond coatings deposited on the surface; The diamond grains or the diamond coating are made conductive by doping elements.

2. The diamond electrode according to claim 1, characterized in that The diamond particles or the diamond particles with diamond coating deposited on the surface have a particle size of 1-5 mm.

3. The diamond electrode according to claim 1, characterized in that The thickness of the diamond coating is 1-20 μm, and the particle size of the diamond grains is 0.5-10 μm; the diamond particles with the diamond coating deposited on the surface form the porous consolidated block through a consolidation layer, the thickness of the consolidation layer is 2-20 μm, and the particle size of the diamond grains is 0.5-15 μm; the sum of the thickness of the diamond coating and the consolidation layer is ≥5 μm; Optionally, the diamond coating has a thickness of 5-15 μm; Optionally, the consolidation layer has a thickness of 5-15 μm.

4. The diamond electrode according to claim 1, characterized in that The diamond particles with diamond coating deposited on the surface have substrate particles inside; the material of the substrate particles is selected from diamond, silicon carbide, silicon dioxide and silicon.

5. The diamond electrode according to claim 4, characterized in that A nano-diamond porous film is also deposited on the surface of the porous consolidated block; the nano-diamond porous film is doped with elements to make it conductive.

6. The diamond electrode according to claim 5, characterized in that The thickness of the nano-diamond porous film is 1-20 μm, and the diameter of the diamond grains is 10-800 nm; Optionally, the thickness of the nano-diamond porous film is 2-12 μm, and the diameter of the diamond grains is 35 nm-500 nm.

7. The diamond electrode according to claim 1 or 5, characterized in that: The doping element is selected from any one of B, P, S, Li and Ba.

8. A method for preparing a diamond electrode according to any one of claims 1 to 3, characterized in that: The following steps are involved: The prepared conductive diamond particles are piled up, and a consolidation layer is further deposited on the surface, thereby consolidating the conductive diamond particles to obtain a porous consolidated block.

9. The method for preparing a diamond electrode according to claim 8, characterized in that: The following steps are also included: The nano-diamond porous membrane is deposited on the surface of the porous consolidated block, specifically: etching is performed on the surface of the porous consolidated block to form etch pits; then deposition and etching are performed in an alternating manner of chemical vapor deposition and etching processes to prepare the nano-diamond porous membrane.

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