Graphene composite high-entropy metal oxide coating titanium-based electrode and preparation method and application thereof

Abstract

The application discloses a graphene composite high-entropy metal oxide coating titanium-based electrode and a preparation method and application thereof, and relates to the technical field of electrode materials, in particular to a graphene composite high-entropy metal oxide coating titanium-based electrode and a preparation method thereof.The preparation method of the graphene composite high-entropy metal oxide coating titanium-based electrode comprises the following steps: S1, pretreating a titanium base; S2, placing the pretreated titanium base in an electrodeposition liquid, wherein the electrodeposition liquid is a mixed liquid of an oxidized graphene solution and a high-entropy metal salt solution; S3, performing electrodeposition on the titanium base by taking the titanium base as an anode and a graphite electrode as a cathode; and S4, performing heat treatment on the titanium base with the coating deposited thereon in an inert gas atmosphere.The graphene composite high-entropy oxide is prepared by electrodeposition, and the process is simple and the preparation cost is low.The graphene composite high-entropy oxide coating titanium electrode prepared by the application can realize the removal of more than 85% of COD within 120 min when used for treating high-concentration wastewater with COD of 500-20000 mg / L, has excellent stability, and has a wide application prospect.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of electrocatalytic wastewater treatment, and particularly relates to a graphene composite high-entropy metal oxide coating titanium-based electrode and a preparation method and application thereof. BACKGROUND

[0002] Electrocatalytic technology is widely applied to the treatment of wastewater in chemical industry, pharmaceutical industry and printing and dyeing industry due to its advantages such as convenient operation, environmental optimization and complete treatment. Electrode material is a key factor determining the electrocatalytic performance. Traditional graphite and stainless steel electrodes are not suitable for application in wastewater treatment due to high cost, large consumption and secondary pollution. Titanium is widely used as electrode substrate material due to its low density and high mechanical strength. Coating metal oxides on titanium as electrodes exhibits good catalytic activity. Commonly used metal oxides include MnO2, PbO2, RuO2, IrO2 and SnO2. However, most oxide electrodes are semiconductor materials with low carrier density and poor conductivity in the bulk phase. In addition, the instability of oxides leads to short service life and cannot realize industrial application. Therefore, it is necessary to develop electrodes with high catalytic activity, good conductivity and long service life.

[0003] High-entropy oxides are a new type of material composed of five or more than five metal or non-metal oxides in an equal molar ratio or close to an equal molar ratio, which exhibits high activity in the field of electrocatalytic water treatment. At present, the preparation methods of high-entropy oxides include mechanical ball milling, laser and magnetron sputtering. Mechanical ball milling is obviously not suitable for preparing titanium-based layer electrodes. Laser and magnetron sputtering are complex to operate and difficult to form high-entropy oxides with uniform particles and high specific surface area, which is not conducive to the catalytic reaction and is not suitable for industrial production. SUMMARY

[0004] In view of this, in order to solve the above problems existing in the prior art, the purpose of the present application is to provide a graphene composite high-entropy oxide coating titanium-based electrode and a preparation method and application thereof. The high dispersion and high conductivity of graphene solve the problems of uneven distribution of high-entropy oxide coating and poor electrical conductivity, improve the interface stability of graphene composite high-entropy oxide coating and titanium substrate, improve the working efficiency and service life of the electrode, and reduce the cost of wastewater treatment.

[0005] To achieve the above purpose, the technical scheme of the present application is as follows:

[0006] A preparation method of a graphene composite high-entropy metal oxide coating titanium-based electrode, comprising the following steps:

[0007] S1: pretreating the titanium substrate;

[0008] S2: placing the pretreated titanium substrate into an electrodeposition solution, the electrodeposition solution being a mixture of a graphene oxide solution and a high-entropy metal salt solution;

[0009] S3: performing electrodeposition on the titanium substrate with the titanium substrate as an anode and a graphite electrode as a cathode;

[0010] S4: performing heat treatment on the titanium substrate with the coating deposited thereon under an inert gas atmosphere to reduce internal stress of the coating and increase interface stability of the coating and the titanium substrate.

[0011] In an embodiment of the application, in the step S2, the concentration of the graphene oxide solution is 3-15 mg / L, the high-entropy metal salt solution is 0.05-0.5 mol / L of NiCl2, 0.05-0.5 mol / L of CoCl2, 0.05-0.5 mol / L of MnCl2, 0.05-0.5 mol / L of ZnCl2 and 0.05-0.5 mol / L of AlCl3, the high-entropy metal salt solution is added to the graphene oxide solution, H2SO4 is added to adjust the pH to 4.0, and the mixture is uniformly mixed to form an electrodeposition solution.

[0012] In an embodiment of the application, the step S3 specifically includes: taking a titanium electrode as an anode and a graphite electrode as a cathode, the area ratio of the anode to the cathode is 1:1, the distance between the two electrodes is 2 cm, and the electrodeposition process parameters are: a deposition current density of 0.2-1.8 A / cm 2 , an operating temperature of 30-60 ℃ and a deposition time of 70-200 min.

[0013] In an embodiment of the application, the step S4 specifically includes: placing the titanium substrate processed in the step S3 into a high-temperature furnace, increasing the temperature to 300-600 ℃ at a temperature increasing rate of 5-10 ℃ / min under a nitrogen atmosphere, and maintaining the temperature for 20-60 min.

[0014] In an embodiment of the application, the pretreatment includes grinding, cleaning, decontamination and etching, the grinding is grinding the surface of the titanium substrate with 1000-mesh sandpaper, the cleaning is cleaning impurities with deionized water, the decontamination operation is ultrasonic treatment of the titanium substrate in anhydrous ethanol for 10-20 min to remove oil stains, and the etching operation is soaking the titanium substrate after decontamination in a 70% phosphoric acid solution at a temperature of 20-40 ℃ for 10-200 min.

[0015] In an embodiment of the application, the graphene composite high-entropy metal oxide coated titanium substrate electrode is prepared by the above preparation method.

[0016] Based on the same inventive concept, the application also provides an application of the graphene composite high-entropy metal oxide coating titanium-based electrode, which is applied to the treatment of organic pollutants in electrocatalytic industrial wastewater as an anode.

[0017] In a preferred embodiment, the concentration of the organic pollutants in the industrial wastewater is 1000-20000 ppm, the cathode is a porous titanium plate, the distance between the cathode and the anode is 1 cm, the power source used is a direct current power source, the current density is 30 mA / cm 2 , and the time is 60 min.

[0018] Compared with the prior art, the application has the following advantages and positive effects:

[0019] The graphene in the application is combined with the metal ions to form high-entropy oxides, and the graphene is reduced to form reduced graphene oxide, thereby effectively improving the conductivity of the composite coating and the stability of the electrode, further improving the electrocatalytic activity, and reducing the cost of wastewater treatment. In the graphene composite high-entropy metal oxide coating titanium electrode system of the application, compared with the technical scheme of electrocatalytic oxidation treatment in the prior art, the application has the advantages of short time consumption and low energy consumption. The preparation method provided by the application is simple and reliable, easy to industrialize, and the graphene composite high-entropy oxide coating titanium electrode prepared by the method can remove more than 85% of COD within 120 min when used to treat high-concentration wastewater with COD of 500-20000 mg / L, has excellent stability, and has a wide application prospect. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 The scanning electron microscope image of the graphene composite high-entropy metal oxide coating titanium electrode prepared in Example 1 of the application;

[0021] Figure 2 The scanning electron microscope image of the graphene composite high-entropy metal oxide coating titanium electrode prepared in Example 2 of the application;

[0022] Figure 3 The scanning electron microscope image of the graphene composite high-entropy metal oxide coating titanium electrode prepared in Example 3 of the application; DETAILED DESCRIPTION

[0023] The application provides a graphene composite high-entropy metal oxide coating titanium-based electrode and a preparation method and application thereof, which are further described in detail in combination with the drawings and specific examples. According to the following description, the advantages and characteristics of the application will be more apparent.

[0024] Example 1

[0025] 1. Pretreatment of the titanium substrate: the pretreatment includes grinding, cleaning, decontamination, and etching;

[0026] The polishing operation is to polish the surface of the titanium substrate using 1000 mesh sandpaper; the cleaning is to clean the impurities using deionized water; the decontamination operation is to ultrasonically treat the titanium substrate in anhydrous ethanol for 10 minutes to remove oil stains; and the etching operation is to immerse the titanium substrate treated in the previous step in a 70% phosphoric acid solution at room temperature for 10 minutes.

[0027] 2. Place the titanium substrate treated in step 1 into the mixed electrodeposition solution, and the electrodeposition solution has the following composition: (1) first configure the graphene oxide solution with a concentration of 3 mg / L; (2) add NiCl2 with a concentration of 0.05 mol / L, CoCl2 with a concentration of 0.05 mol / L, MnCl2 with a concentration of 0.05 mol / L, ZnCl2 with a concentration of 0.05 mol / L, and AlCl3 with a concentration of 0.05 mol / L into the graphene oxide solution, add H2SO4 to adjust the pH value to 4.0, and mix uniformly to form the electrodeposition solution.

[0028] 3. Take the titanium substrate as the anode and the graphite electrode as the cathode, and the area ratio of the cathode to the anode is 1:1, and the distance between the two electrodes is 2 cm. The electrodeposition process parameters are as follows: the deposition current density is 0.2 A / cm 2 , the operating temperature is 30°C, and the deposition time is 70 min.

[0029] 4. Heat treat the graphene composite high-entropy oxide coated titanium electrode obtained in step 3, and the temperature is increased to 300°C at a heating rate of 5°C / min in an inert nitrogen atmosphere, and the holding time is 20 min.

[0030] Further, the obtained graphene composite high-entropy metal oxide coated titanium electrode is applied to electrocatalytic industrial wastewater treatment, the concentration of organic pollutants in the industrial wastewater is 1000 ppm, the anode is the graphene composite high-entropy metal oxide coated titanium electrode, the cathode is a porous titanium plate, the distance between the cathode and the anode is 1 cm, the power source used is a direct current power source, the current density is 30 mA / cm 2 , and the time is 60 min. The obtained results are listed in Table 1.

[0031] Example 2

[0032] 1. Pretreat the titanium substrate; the pretreatment includes polishing, cleaning, decontamination, and etching.

[0033] The polishing operation is to polish the surface of the titanium substrate using 1000 mesh sandpaper; the cleaning is to clean the impurities using deionized water; the decontamination operation is to ultrasonically treat the titanium substrate in anhydrous ethanol for 15 minutes to remove oil stains; and the etching operation is to immerse the titanium substrate treated in the previous step in a 70% phosphoric acid solution at room temperature for 100 minutes.

[0034] 2. Put the titanium substrate treated in step 1 into the mixed electrodeposition solution, and the electrodeposition solution comprises: (1) prepare a graphene oxide solution with a concentration of 10 mg / L; (2) add 0.2 mol / L of NiCl2, 0.2 mol / L of CoCl2, 0.2 mol / L of MnCl2, 0.2 mol / L of ZnCl2 and 0.2 mol / L of AlCl3 into the graphene oxide solution, add H2SO4 to adjust the pH value to 4.0, and mix uniformly to form the electrodeposition solution.

[0035] 3. Take the titanium substrate as an anode and a graphite electrode as a cathode, and the area ratio of the anode to the cathode is 1:1, and the distance between the two electrodes is 2 cm. The electrodeposition process parameters are as follows: the deposition current density is 0.8 A / cm 2 , the operating temperature is 50℃, and the deposition time is 100 min.

[0036] 4. Heat treat the graphene composite high-entropy oxide coating titanium electrode obtained in step 3, and the temperature is increased to 400℃ at a heating rate of 8℃ / min in an inert nitrogen atmosphere, and the holding time is 30 min.

[0037] Further, the obtained graphene composite high-entropy metal oxide coating titanium electrode is applied to electrocatalytic industrial wastewater treatment, the concentration of organic pollutants in the industrial wastewater is 5000 ppm, the anode is the graphene composite high-entropy metal oxide coating titanium electrode, the cathode is a porous titanium plate, the distance between the anode and the cathode is 1 cm, the power source used is a direct current power source, the current density is 30 mA / cm 2 , and the time is 60 min. The obtained results are listed in Table 1.

[0038] Example 3

[0039] 1. Pretreat the titanium substrate; the pretreatment comprises grinding, cleaning, decontamination and etching;

[0040] The grinding operation is to grind the surface of the titanium substrate using 1000-mesh sandpaper; the cleaning is to clean impurities using deionized water; the decontamination operation is to place the titanium substrate in anhydrous ethanol for ultrasonic treatment for 20 minutes to remove oil stains; and the etching operation is to place the titanium substrate treated in the previous step in a 70% phosphoric acid solution for room temperature immersion treatment for 200 minutes.

[0041] 2. Put the treated titanium substrate in the mixed electrodeposition solution, and the electrodeposition solution comprises: (1) prepare a graphene oxide solution with a concentration of 15 mg / L; (2) add 0.5 mol / L of NiCl2, 0.5 mol / L of CoCl2, 0.5 mol / L of MnCl2, 0.5 mol / L of ZnCl2 and 0.5 mol / L of AlCl3 into the graphene oxide solution, and add H2SO4 to adjust the pH value to 4.0, and mix uniformly to form the electrodeposition solution.

[0042] 3. Take the titanium substrate as the anode and the graphite electrode as the cathode, and the area ratio of the anode to the cathode is 1:1, and the distance between the two electrodes is 2 cm. The electrodeposition process parameters are as follows: the deposition current density is 1.8 A / cm 2 , the operating temperature is 60°C, and the deposition time is 200 min.

[0043] 4. Heat treat the graphene composite high-entropy oxide coating titanium electrode obtained in step 3, and the temperature is increased to 600°C at a heating rate of 10°C / min in an inert nitrogen atmosphere, and the holding time is 60 min.

[0044] Further, the obtained graphene composite high-entropy metal oxide coating titanium electrode is applied to electrocatalytic industrial wastewater treatment, the concentration of organic pollutants in the industrial wastewater is 20000 ppm, the anode is the graphene composite high-entropy metal oxide coating titanium electrode, the cathode is a porous titanium plate, the distance between the anode and the cathode is 1 cm, the power source used is a direct current power source, the current density is 30 mA / cm 2 , and the time is 60 min. The obtained results are shown in Table 1.

[0045] Comparative Example:

[0046] In order to compare the electrocatalytic effect of the prepared graphene composite high-entropy metal oxide coating titanium electrode, the untreated titanium substrate is used as the anode, the porous titanium plate is used as the cathode, and the other conditions remain the same as in Example 2, and the organic pollutants in the industrial wastewater are electrocatalytically degraded. The obtained results are shown in Table 1.

[0047] Figures 1-3 The scanning electron microscope images of the graphene composite high-entropy metal oxide coating titanium electrodes prepared in Examples 1-3 can be seen, and the formed graphene composite high-entropy metal oxide coating is uniformly distributed and better coated on the titanium metal substrate, which lays a foundation for excellent electrocatalytic performance.

[0048] Table 1 Experimental effects of examples and comparative examples

[0049] COD removal (%) Example 1 93.5 Example 2 96.2 Example 3 94.7 Comparative Example 78.6

[0050] As shown in the above table, the preparation method of the graphene composite high-entropy metal oxide coating titanium electrode can effectively treat the organic pollutants in industrial wastewater, and the COD removal rate is more than 90%. The composite electrode has the advantages of simple and reliable preparation method, easy industrial production and high electrocatalytic oxidation performance, and has a good application prospect.

[0051] The embodiments of the application are described in detail above with reference to the drawings, but the application is not limited to the above embodiments. Even if various changes are made to the application, as long as the changes fall within the scope of the claims of the application and equivalent technologies thereof, they still fall within the protection scope of the application.

Claims

1. A method for preparing a graphene-composite high-entropy metal oxide coated titanium-based electrode, characterized in that, Includes the following steps: S1: Pretreatment of the titanium matrix; S2: The pretreated titanium substrate is placed in an electrodeposition solution, which is a mixture of graphene oxide solution and high-entropy metal salt solution; wherein the high-entropy metal salt solution consists of 0.05-0.5 mol / L NiCl2, 0.05-0.5 mol / L CoCl2, 0.05-0.5 mol / L MnCl2, 0.05-0.5 mol / L ZnCl2 and 0.05-0.5 mol / L AlCl3. The high-entropy metal salt solution is added to the graphene oxide solution, and H2SO4 is added to adjust the pH to 4.

0. The mixture is then thoroughly mixed to form the electrodeposition solution. S3: Electrodeposition is performed on a titanium substrate using a titanium substrate as the anode and a graphite electrode as the cathode. S4: Heat-treat the coated titanium substrate in an inert gas atmosphere.

2. The method for preparing the graphene-composite high-entropy metal oxide coated titanium-based electrode according to claim 1, characterized in that, In step S2, the concentration of the graphene oxide solution is 3-15 mg / L.

3. The method for preparing the graphene-composite high-entropy metal oxide coated titanium-based electrode according to claim 1, characterized in that, Step S3 specifically involves using a titanium electrode as the anode and a graphite electrode as the cathode, with an anode-to-cathode area ratio of 1:1 and a 2cm distance between the two electrodes. The electrodeposition process parameters are: a deposition current density of 0.2-1.8 A / cm². 2 The operating temperature is 30-60℃ and the deposition time is 70-200min.

4. The method for preparing the graphene-composite high-entropy metal oxide coated titanium-based electrode according to claim 1, characterized in that, Specifically, step S4 involves placing the titanium substrate processed in step S3 into a high-temperature furnace, raising the temperature to 300-600°C at a heating rate of 5-10°C / min under a nitrogen atmosphere, and holding the temperature for 20-60 minutes.

5. The method for preparing the graphene-composite high-entropy metal oxide coated titanium-based electrode according to claim 1, characterized in that, The pretreatment includes polishing, cleaning, decontamination and etching. The etching operation involves placing the decontaminated titanium substrate in a 70% phosphoric acid solution and immersing it at a temperature of 20-40°C for 10-200 minutes.

6. A graphene-composite high-entropy metal oxide coated titanium-based electrode, characterized in that, The graphene-composite high-entropy metal oxide coated titanium-based electrode is prepared by the preparation method described in any one of claims 1-5.

7. An application of a graphene-composite high-entropy metal oxide coated titanium-based electrode prepared by the preparation method according to any one of claims 1-5, characterized in that, It is used as an anode in the electrocatalytic treatment of organic pollutants in industrial wastewater.

8. The application of the graphene-composite high-entropy metal oxide coated titanium-based electrode according to claim 7, characterized in that, The concentration of organic pollutants in the industrial wastewater is 1000-20000 ppm. The cathode is a porous titanium plate, the distance between the anode and cathode is 1 cm, and the power supply is a DC power supply with a current density of 30 mA / cm². 2 The time is 60 minutes.

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