A porous graphene oxide / boron-doped diamond semiconductor composite material, a preparation method therefor, and an application thereof

Abstract

The application discloses a kind of porous graphene oxide / boron-doped diamond semiconductor composite material and its preparation method and application, add scale graphite into sodium cholate solution, shear emulsification, form emulsified graphite, add sodium silicate in emulsified graphite, and obtain emulsified mixed solution after adjusting pH acidification, boron-doped diamond film layer composite material is infiltrated in emulsified mixed solution, take out and dry, heat treatment is carried out, and porous graphene oxide / boron-doped diamond semiconductor composite material is obtained, the porous graphene oxide / boron-doped diamond semiconductor composite material provided by the application combines together high oxygen evolution potential of boron-doped diamond and excellent electron transport performance of graphite, by end group modification, high-temperature etching, enhance the hydrophilicity and active area of graphene, to promote the progress of surface reaction, accelerate the synthesis of ozone, and improve the performance of ozone module.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of porous graphene oxide / boron-doped diamond semiconductor composite material and its preparation method and application, belong to semiconductor composite material preparation technical field. BACKGROUND

[0002] An ozone generator is a device that generates ozone by ionizing oxygen molecules in the air. Ozone generators typically use a high-voltage electric field to convert oxygen molecules into ozone. Ozone generators can be used for air purification, disinfection, and deodorization, etc., because ozone has strong oxidizing and bactericidal effects.

[0003] Electrodes are key components in ozone generators, used to ionize oxygen molecules in the air and generate ozone. In the prior art, electrodes used in ozone generators mainly include flat plate boron-doped diamond electrodes (boron-doped diamond electrodes), powder boron-doped diamond electrodes (fixed on solid electrolyte membranes), lead dioxide electrodes, tin-antimony electrodes, etc.

[0004] However, these electrodes all have low current efficiency, slow mass transfer, and low electrochemical reaction rate. SUMMARY

[0005] To overcome the deficiencies of the prior art, the first object of the present application is to provide a method for preparing a porous graphene oxide / boron-doped diamond semiconductor composite material.

[0006] The second object of the present application is to provide a porous graphene oxide / boron-doped diamond semiconductor composite material prepared by the above-mentioned preparation method.

[0007] The third object of the present application is to provide an application of the porous graphene oxide / boron-doped diamond semiconductor composite material prepared by the above-mentioned preparation method.

[0008] To achieve the above-mentioned objects, the present application adopts the following technical solutions:

[0009] The present application provides a method for preparing a porous graphene oxide / boron-doped diamond semiconductor composite material. Graphite flakes are added to a sodium cholate solution, and shear emulsification is performed to form emulsified graphite. Sodium silicate is added to the emulsified graphite, and the pH is adjusted and acidified to obtain an emulsified mixture. A boron-doped diamond film layer composite material is immersed in the emulsified mixture, and after drying and heat treatment, a porous graphene oxide / boron-doped diamond semiconductor composite material is obtained.

[0010] The preparation method of the present application uses the emulsified mixed solution formed by mixing the emulsified graphite liquid and silica gel (acidified sodium silicate) as the impregnating agent to infiltrate the boron-doped diamond film layer composite material, so that the emulsified mixed solution covers the surface of the boron-doped diamond film layer of the boron-doped diamond film layer composite material, and after drying, a graphene thin layer is formed to cover the surface of the boron-doped diamond film layer, and then heat treatment is carried out. During the heat treatment process, on the one hand, the graphene combines with the boron-doped diamond film layer, and on the other hand, the silica gel embedded in the graphene will pyrolyze, which will destroy the surface of the graphene layer, thereby creating a porous graphene surface. The etched graphene hollows are prone to oxidation reaction, and a large number of oxygen-containing groups are generated on the surface, that is, a porous graphene is formed, thereby forming a porous graphene oxide / boron-doped diamond semiconductor composite material.

[0011]

[0012] The inventors found that the porous graphene oxide / boron-doped diamond semiconductor composite material prepared by the emulsification of the present application has the advantages that the graphene film layer is uniformly distributed on the boron-doped diamond film layer, has good stability, and the graphene / boron-doped diamond composite material is etched by sodium silicate at high temperature to form a porous structure, thereby enhancing the interface reaction area and water absorption. When the graphene / boron-doped diamond composite material is used as an electrode of an ozone generator, the interface electrocatalytic ozone synthesis reaction of the electrode is promoted, in addition, the oxygen-containing end groups formed by the graphene film layer in the presence of silicate at high temperature can improve the hydrophilicity of the electrode and induce the interface electrocatalytic ozone synthesis reaction, thereby improving the efficiency of the ozone generator.

[0013] In a preferred embodiment, the concentration of the sodium cholate solution is 0.05-0.2 mol / L, preferably 0.1 mol / L.

[0014] In a preferred embodiment, the solid-liquid mass / volume ratio of the flake graphite and the sodium cholate solution is 3-8 g:500 ml.

[0015] In a preferred embodiment, the rotation speed of the shear emulsification is 100-200 r / min, and the shear emulsification time is 0.5-2 h, preferably 1 h.

[0016] In a preferred embodiment, the mass ratio of sodium silicate to flake graphite is 0.5-0.6:1. In the present application, the mass of sodium silicate and flake graphite needs to be effectively controlled. If the content of sodium silicate is too low, it is not possible to form enough silica sol, and thus it is not possible to generate enough damage sites on the graphene surface in the later pyrolysis link, which will prevent the effective formation of porous graphene and also reduce the content of oxygen-containing end groups.

[0017] In a preferred embodiment, the PH of the emulsified mixed solution is 3.5-4.5, preferably 4.

[0018] In actual operation, sodium silicate is added into the emulsified graphite to obtain a mixed solution, and then 3 mol / L hydrochloric acid solution is added dropwise until the pH of the emulsified mixed solution is about 4.

[0019] Preferably, the boron-doped diamond film layer composite material is composed of a substrate and a boron-doped diamond film layer arranged on the surface of the substrate.

[0020] Further preferably, the substrate is selected from one of silicon, silicon carbide, titanium, niobium and tantalum.

[0021] Further preferably, the substrate has a shape selected from one of a flat plate and a three-dimensional foam.

[0022] The boron-doped diamond film layer composite material is prepared by using the existing conventional CVD process.

[0023] Preferably, the soaking time is 20 s to 5 min.

[0024] Preferably, the drying temperature is 60-100℃, preferably 80℃, and the drying time is 18-26 h, preferably 24 h.

[0025] Preferably, the heat treatment temperature is 150-500℃, preferably 200-500℃, the heat treatment time is 1-5 h, the heating rate is 3-10℃ / min, and preferably 5℃ / min.

[0026] The application further provides a porous graphene oxide / boron-doped diamond semiconductor composite material prepared by the above preparation method.

[0027] The application further provides an application of the porous graphene oxide / boron-doped diamond semiconductor composite material prepared by the above preparation method, wherein the porous graphene oxide / boron-doped diamond semiconductor composite material is used as an electrode of an ozone generator or as an electrolytic anode of a water treatment electro-oxidation module.

[0028] Principle and advantage

[0029] The preparation method of the present application uses an emulsified mixed solution formed by mixing an emulsified graphite liquid and silica gel (acidified sodium silicate) as an impregnating agent to infiltrate the boron-doped diamond film layer composite material, so that the emulsified mixed solution covers the surface of the boron-doped diamond film layer of the boron-doped diamond film layer composite material, and after drying, a graphene thin layer is formed to cover the surface of the boron-doped diamond film layer, and then heat treatment is performed. During the heat treatment, on the one hand, the graphene combines with the boron-doped diamond film layer, and on the other hand, the silica gel embedded in the graphene will pyrolyze, which will destroy the surface of the graphene layer, thereby creating a porous graphene surface. The etched graphene cavities are prone to oxidation reaction, and a large number of oxygen-containing groups are generated on the surface, that is, a porous graphene is formed, thereby forming a porous graphene oxide / boron-doped diamond semiconductor composite material.

[0030] The porous graphene oxide / boron-doped diamond semiconductor composite material provided by the present application combines the high oxygen evolution potential of boron-doped diamond with the excellent electron transport performance of graphite, thereby enhancing the hydrophilicity and active area of graphene through end group modification and high-temperature etching, promoting the progress of surface reaction, accelerating the synthesis of ozone, and improving the performance of the ozone module. DETAILED DESCRIPTION

[0031] Example 1

[0032] SiC ceramic is used as the substrate, the substrate is ultrasonically cleaned, the substrate is vertically suspended and immersed in a suspension liquid containing nano-diamond seeds, ultrasonic oscillation is performed for 20 min, and finally alcohol cleaning and drying are performed to obtain the substrate, the particle size of the nano-diamond seeds is 5 nm, and the mass concentration of the nano-diamond seeds in the suspension liquid is 2%.

[0033] Then, the substrate with the nano-diamond seeds is placed in a chemical vapor deposition furnace: the mass flow ratio of the gases is hydrogen:methane:boration = 97:2:0.5, the growth pressure is 2 Kpa, the growth temperature is 800℃, the growth times are 4, the substrate is taken out after each growth, and then the growth is continued after being replaced, the single growth time is 10 h; and the boron-doped diamond film layer composite material is obtained after 4 growths.

[0034] 5g flake graphite was mixed with 500ml 0.1mol / L sodium cholate solution, and emulsion treatment was performed by a high-speed shearing emulsifier, with the rotating speed set at 150r / min. After stirring for 1 hour, emulsified graphite was formed. Sodium silicate was added to the emulsified graphite solution, with the mass ratio of sodium silicate to flake graphite controlled at 0.5:1. After stirring, 3mol / L hydrochloric acid solution was added dropwise to the mixed solution until the pH of the emulsion mixture was equal to 4. The boron-doped diamond film layer composite material was immersed in the emulsion mixture for 3min, and then placed in an oven at 80℃ for 24 hours until the surface was dry. Then, the material was placed in a muffle furnace for high-temperature heating, with the heating rate being 5℃ / min, the heating temperature being between 350℃, and the heating time being 3 hours. Thus, a porous graphene oxide / boron-doped diamond semiconductor composite material was obtained.

[0035] The prepared porous graphene oxide electrode was assembled into an ozone generator module (with a size of 7.8mm*25mm) as an anode and a cathode (with a proton membrane separating the electrodes), and connected to a beaker containing 1L of pure water and a peristaltic pump through a hose. The flow rate was adjusted to 100ml / min, and after 1 minute, the ozone concentration in the beaker was measured by iodometric method to be 2.7-3ppm.

[0036] Example 2

[0037] Titanium plates were used as substrates, which were ultrasonically cleaned and then vertically hung in a suspension containing nano-diamond seeds. Ultrasonic oscillation was performed for 20min, and finally the substrates were cleaned with alcohol and dried. The particle size of the nano-diamond seeds was 8nm, and the mass concentration of the nano-diamond seeds in the suspension was 2%.

[0038] Then, the substrate with the nano-diamond seeds was placed in a chemical vapor deposition furnace. The mass flow ratio of the gases introduced was hydrogen:methane:boration = 97:3:1.3, the growth pressure was 3Kpa, the growth temperature was 900℃, and the growth number was 4. After each growth, the substrate was taken out, replaced, and then continued to grow. The single growth time was 12h, and after 4 growths, a boron-doped diamond film layer composite material was obtained.

[0039] 5g of flake graphite was mixed with 500ml of 0.1mol / L sodium cholate solution, the stirring speed was set between 100r / min, and emulsified graphite was formed after 1 hour of stirring. Sodium silicate was added to the emulsified graphite solution, the mass ratio of the added sodium silicate to the flake graphite was controlled to be 0.5:1, and after stirring, 3mol / L hydrochloric acid solution was added dropwise to the mixed solution until the pH of the emulsified mixed solution was about 4. The boron-doped diamond film layer electrode was immersed in the emulsified mixed solution for 1min, and then was placed in an oven at 80°C for 24 hours until the surface was dry. Then the electrode was placed in a muffle furnace for high-temperature heating, the heating rate was 5°C / min, the heating temperature was 200°C, and the heating time was 5 hours, to obtain a porous graphene oxide / boron-doped diamond semiconductor composite material.

[0040] The prepared porous graphene oxide electrode was assembled into an ozone generator module (with a size of 7.8mm*25mm) as an anode and a cathode (the electrodes were separated by a proton membrane), and the module was connected to a beaker containing 1L of pure water and a peristaltic pump through a hose. The flow rate was adjusted to 100ml / min, and after 1 minute, the ozone in the beaker was determined multiple times using iodimetry, and the concentration range was 2.5-3.2ppm.

[0041] Example 3

[0042] In this example, the preparation method of the boron-doped diamond film layer composite material (boron-doped diamond film layer electrode) was the same as that in Example 1.

[0043] 5g of flake graphite was mixed with 500ml of 0.1mol / L sodium cholate solution, the stirring speed was set between 100r / min, and emulsified graphite was formed after 1 hour of stirring. Sodium silicate was added to the emulsified graphite solution, the mass ratio of the added sodium silicate to the flake graphite was controlled to be 0.5:1, and after stirring, 3mol / L hydrochloric acid solution was added dropwise to the mixed solution until the pH of the emulsified mixed solution was about 4. The boron-doped diamond film layer electrode was immersed in the emulsified mixed solution for 1min, and then was placed in an oven at 80°C for 24 hours until the surface was dry. Then the electrode was placed in a muffle furnace for high-temperature heating, the heating rate was 5°C / min, the heating temperature was 200°C, and the heating time was 5 hours, to obtain a porous graphene oxide / boron-doped diamond semiconductor composite material

[0044] The prepared porous graphene oxide electrode was assembled into an ozone generator module (with a size of 7.8mm*25mm) as an anode and a cathode (the electrodes were separated by a proton membrane), and the module was connected to a beaker containing 1L of pure water and a peristaltic pump through a hose. The flow rate was adjusted to 100ml / min, and after 1 minute, the ozone in the beaker was determined multiple times using iodimetry, and the concentration range was 2.5-3.2ppm.

[0045] Comparative Example 1

[0046] Other conditions are the same as example 1, only no sodium silicate is added in the emulsified graphite liquid, finally the graphene / boron-doped diamond composite material is obtained.

[0047] The prepared porous graphene oxide electrode is assembled as anode and cathode to form an ozone generator module (size: 7.8mm*25mm) (the electrodes are separated by a proton membrane), the module is connected to a beaker containing 1L pure water and a peristaltic pump through a hose, the flow rate is adjusted to 100ml / min, after 1 minute, the ozone in the beaker is measured multiple times using iodometric method, the concentration range is 0.7 to 1.5ppm.

[0048] Comparative example 2

[0049] Other conditions are the same as example 1, only the mass ratio of sodium silicate added to the mass of flake graphite is controlled at 0.7:1.

[0050] The prepared porous graphene oxide electrode is assembled as anode and cathode to form an ozone generator module (size: 7.8mm*25mm) (the electrodes are separated by a proton membrane), the module is connected to a beaker containing 1L pure water and a peristaltic pump through a hose, the flow rate is adjusted to 100ml / min, after 1 minute, the ozone in the beaker is measured multiple times using iodometric method, the concentration range is 0.5 to 1.5ppm.

Claims

1. A method for preparing a porous graphene oxide / boron-doped diamond semiconductor composite material, characterized in that: Flake graphite is added to sodium cholate solution and sheared and emulsified to form emulsified graphite. Sodium silicate is added to the emulsified graphite and the pH is adjusted to acidify it to obtain an emulsified mixture. Boron-doped diamond film composite material is immersed in the emulsified mixture, taken out and dried, and then heat-treated to obtain a porous graphene oxide / boron-doped diamond semiconductor composite material. The mass ratio of sodium silicate to flake graphite is 0.5~0.6:

1.

2. The method for preparing a porous graphene oxide / boron-doped diamond semiconductor composite material according to claim 1, characterized in that: The concentration of the sodium cholate solution is 0.05~0.2 mol / L; The solid-liquid mass-volume ratio of the flake graphite to the sodium cholate solution is 3-8 g: 500 ml.

3. The method for preparing a porous graphene oxide / boron-doped diamond semiconductor composite material according to claim 1, characterized in that: The rotation speed of the shear emulsification is 100~200 r / min, and the shear emulsification time is 0.5~2 h.

4. The method for preparing a porous graphene oxide / boron-doped diamond semiconductor composite material according to claim 1, characterized in that: The pH of the emulsified mixture is 3.5 to 4.

5.

5. The method for preparing a porous graphene oxide / boron-doped diamond semiconductor composite material according to claim 1, characterized in that: The boron-doped diamond film composite material consists of a substrate and a boron-doped diamond film layer disposed on the surface of the substrate. The substrate is selected from one of silicon, silicon carbide, titanium, niobium, and tantalum; The substrate can be either a flat plate or a three-dimensional foam.

6. The method for preparing a porous graphene oxide / boron-doped diamond semiconductor composite material according to claim 1, characterized in that: The soaking time is 20 seconds to 5 minutes; The drying temperature is 60~100℃, and the drying time is 18~26h.

7. The method for preparing a porous graphene oxide / boron-doped diamond semiconductor composite material according to claim 1, characterized in that: The heat treatment temperature is 150°C to 500°C, the heat treatment time is 1 to 5 hours, and the heating rate is 3 to 10°C / min.

8. The porous graphene oxide / boron-doped diamond semiconductor composite material prepared by the preparation method according to any one of claims 1-7.

9. The application of the porous graphene oxide / boron-doped diamond semiconductor composite material prepared by the preparation method according to any one of claims 1-7, characterized in that: The porous graphene oxide / boron-doped diamond semiconductor composite material can be used as an electrode in an ozone generator or as an electrolytic anode in a water treatment electro-oxidation module.

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