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

Abstract

The invention discloses a graphene composite high-entropy metal oxide coating titanium-based electrode as well as a preparation method and application thereof, and the preparation method of the graphene composite high-entropy metal oxide coating titanium-based electrode comprises the following steps: S1, pretreating a titanium substrate; s2, the pretreated titanium substrate is placed in an electro-deposition solution, wherein the electro-deposition solution is a mixed solution of a graphene oxide solution and a high-entropy metal salt solution; s3, the titanium substrate is used as an anode, a graphite electrode is used as a cathode, and electro-deposition is carried out on the titanium substrate; and S4, in the inert gas atmosphere, heat treatment is carried out on the titanium substrate deposited with the coating. The graphene composite high-entropy oxide is prepared through electro-deposition, the process is simple, and the preparation cost is low. When the prepared graphene composite high-entropy oxide coating titanium electrode is used for treating high-concentration wastewater with the COD ranging from 500 mg / L to 20000 mg / L, 85% or above of COD can be removed within 120 min, stability is excellent, and wide application prospects are achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrocatalytic sewage treatment, and in particular relates to a graphene composite high entropy metal oxide coating titanium-based electrode and a preparation method and application thereof. Background Art

[0002] Electrocatalytic technology is widely used in treating wastewater in the chemical, pharmaceutical, printing and dyeing industries due to its many advantages such as easy operation, environmental optimization, and thorough treatment. Electrode materials are the key factor in determining electrocatalytic performance. Traditional graphite and stainless steel electrodes are not suitable for wastewater treatment due to their high cost, high consumption, and easy secondary pollution. Titanium is widely used as an electrode matrix material due to its advantages such as low density and high mechanical strength. Coating metal oxides on it to make electrodes shows good catalytic activity. Commonly used metal oxides are MnO 2 , PbO 2 、RuO 2 、IrO 2 SnO 2 However, most oxide electrodes are semiconductor materials with low carrier density and poor conductivity in the bulk phase. In addition, the instability of oxides shortens their service life and makes them incapable of 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 5 or more metal or non-metal oxides in equimolar or nearly equimolar ratios, and they show 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 complicated to operate, and it is 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 of the invention

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

[0005] To achieve the above object, the technical solution of the present invention is:

[0006] A method for preparing a graphene composite high entropy metal oxide coating titanium-based electrode comprises the following steps:

[0007] S1: pre-treating the titanium substrate;

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

[0009] S3: Electrodeposition is performed on the titanium substrate using the titanium substrate as the anode and the graphite electrode as the cathode;

[0010] S4: In an inert gas atmosphere, the titanium substrate with the coating deposited thereon is heat treated to reduce the internal stress of the coating and increase the interface stability between the coating and the titanium substrate.

[0011] In a preferred embodiment of the present invention, in step S2, the concentration of the graphene oxide solution is 3-15 mg / L, and the high entropy metal salt solution is 0.05-0.5 mol / L NiCl 2 , 0.05-0.5 mol / L CoCl 2 , 0.05-0.5 mol / L MnCl 2 , 0.05-0.5 mol / L ZnCl 2 and 0.05-0.5 mol / L AlCl 3 , adding a high entropy metal salt solution to the graphene oxide solution, and adding H 2 SO 4 The pH was adjusted to 4.0 and mixed evenly to form an electrodeposition solution.

[0012] In a preferred embodiment of the present invention, the step S3 is specifically as follows: a titanium electrode is used as an anode, a graphite electrode is used as a cathode, the anode-cathode area ratio 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 , the operating temperature is 30-60℃ and the deposition time is 70-200min.

[0013] In a preferred embodiment of the present invention, step S4 is specifically to place the titanium substrate processed in step S3 in a high temperature furnace, and raise the temperature to 300-600°C at a heating rate of 5-10°C / min in a nitrogen atmosphere for 20-60 minutes.

[0014] In a preferred embodiment of the present invention, the pretreatment includes grinding, cleaning, decontamination and etching, the grinding is to use 1000 mesh sandpaper to grind the surface of the titanium substrate, the cleaning is to use deionized water to clean impurities, the decontamination operation is to place the titanium substrate in anhydrous ethanol for ultrasonic treatment for 10-20 minutes to remove oil stains; the etching operation is to place the decontaminated titanium substrate in a 70% phosphoric acid solution and soak it at a temperature of 20-40°C for 10-200 minutes.

[0015] In a preferred embodiment of the present invention, the graphene composite high entropy metal oxide coated titanium-based electrode is prepared by the above-mentioned preparation method.

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

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

[0018] Due to the adoption of the above technical solution, the present invention has the following advantages and positive effects compared with the prior art:

[0019] The present invention utilizes the oxygen rich in graphene oxide to combine with electrodeposited metal ions to form high entropy oxides, and the graphene oxide forms 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 sewage treatment. In the graphene composite high entropy metal oxide coating titanium electrode system of the present invention, compared with the technical scheme of electrocatalytic oxidation treatment in the existing related technology, it also has the advantages of short time consumption and low energy consumption. The preparation method provided by the present invention is simple and reliable, and is easy to industrialize. When the prepared graphene composite high entropy oxide coating titanium electrode is used to treat high-concentration wastewater with a COD of 500-20000 mg / L, more than 85% of COD can be removed within 120 minutes, and the stability is excellent, and it has broad application prospects. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is a scanning electron microscope image of the graphene composite high entropy metal oxide coated titanium electrode prepared in Example 1 of the present invention;

[0021] Figure 2 This is a scanning electron microscope image of the graphene composite high entropy metal oxide coated titanium electrode prepared in Example 2 of the present invention;

[0022] Figure 3 This is a scanning electron microscope image of the graphene composite high entropy metal oxide coated titanium electrode prepared in Example 3 of the present invention; DETAILED DESCRIPTION

[0023] The following is a further detailed description of a graphene composite high entropy metal oxide coating titanium-based electrode and its preparation method and application proposed by the present invention in conjunction with the accompanying drawings and specific embodiments. The advantages and features of the present invention will become clearer according to the following description.

[0024] Example 1

[0025] 1. Pre-treating the titanium substrate: the pre-treatment includes grinding-cleaning-decontamination-etching;

[0026] The polishing operation is to use 1000 mesh sandpaper to polish the surface of the titanium substrate; the cleaning is to use deionized water to clean impurities; the decontamination operation is to place the titanium substrate in anhydrous ethanol for ultrasonic treatment for 10 minutes to remove oil stains; the etching operation is to place the previously treated titanium substrate in a 70% phosphoric acid solution and soak it at room temperature for 10 minutes.

[0027] 2. The titanium substrate treated in step 1 is placed in a mixed electrodeposition solution, the composition of which is as follows: (1) a graphene oxide solution with a concentration of 3 mg / L is prepared; (2) NiCl with a concentration of 0.05 mol / L is added to the graphene oxide solution. 2 , 0.05 mol / L CoCl 2 , 0.05 mol / L MnCl 2 , 0.05 mol / L ZnCl 2 and 0.05 mol / L AlCl 3 , add H 2 SO 4 The pH value was adjusted to 4.0 and mixed evenly to form an electrodeposition solution.

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

[0029] 4. The graphene composite high entropy oxide coated titanium-based electrode obtained by electrodeposition in step 3 was heat treated by raising the temperature to 300°C at a heating rate of 5°C / min in an inert nitrogen atmosphere for 20 min.

[0030] Furthermore, the obtained graphene composite high entropy metal oxide coated titanium electrode was applied to electrocatalytic industrial wastewater treatment, the concentration of organic pollutants in the industrial wastewater was 1000ppm, the anode was a graphene composite high entropy metal oxide coated titanium electrode, the cathode was a porous titanium plate, the distance between the positive and negative electrodes was 1cm, the power supply was a DC power supply, and the current density was 30mA / cm 2 The results are listed in Table 1.

[0031] Example 2

[0032] 1. Pre-treating the titanium substrate; the pre-treatment includes grinding-cleaning-decontamination-etching;

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

[0034] 2. The titanium substrate treated in step 1 is placed in a mixed electrodeposition solution, the composition of which is as follows: (1) a graphene oxide solution with a concentration of 10 mg / L is prepared; (2) NiCl with a concentration of 0.2 mol / L is added to the graphene oxide solution. 2 , 0.2 mol / L CoCl 2 , 0.2 mol / L MnCl 2 , 0.2 mol / L ZnCl 2 and 0.2 mol / L AlCl 3 , add H 2 SO 4 The pH value was adjusted to 4.0 and mixed evenly to form an electrodeposition solution.

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

[0036] 4. The graphene composite high entropy oxide coated titanium-based electrode obtained by electrodeposition in step 3 was heat treated by raising the temperature to 400°C at a heating rate of 8°C / min in an inert nitrogen atmosphere for 30 minutes.

[0037] Furthermore, the obtained graphene composite high entropy metal oxide coated titanium electrode was applied to electrocatalytic industrial wastewater treatment, the concentration of organic pollutants in the industrial wastewater was 5000ppm, the anode was a graphene composite high entropy metal oxide coated titanium electrode, the cathode was a porous titanium plate, the distance between the positive and negative electrodes was 1cm, the power supply was a DC power supply, and the current density was 30mA / cm 2 The results are listed in Table 1.

[0038] Example 3

[0039] 1. Pre-treating the titanium substrate; the pre-treatment includes grinding-cleaning-decontamination-etching;

[0040] The polishing operation is to use 1000 mesh sandpaper to polish the surface of the titanium substrate; the cleaning is to use deionized water to clean impurities; the decontamination operation is to place the titanium substrate in anhydrous ethanol for ultrasonic treatment for 20 minutes to remove oil stains; the etching operation is to place the previously treated titanium substrate in a 70% phosphoric acid solution and immerse it at room temperature for 200 minutes.

[0041] 2. The titanium substrate treated in step 1 is placed in a mixed electrodeposition solution, the composition of which is as follows: (1) a graphene oxide solution with a concentration of 15 mg / L is prepared; (2) NiCl with a concentration of 0.5 mol / L is added to the graphene oxide solution. 2 , 0.5 mol / L CoCl 2 , 0.5 mol / L MnCl 2 , 0.5 mol / L ZnCl 2 and 0.5 mol / L AlCl 3 , add H 2 SO 4 The pH value was adjusted to 4.0 and mixed evenly to form an electrodeposition solution.

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

[0043] 4. The graphene composite high entropy oxide coated titanium-based electrode obtained by electrodeposition in step 3 was heat treated by raising the temperature to 600°C at a heating rate of 10°C / min in an inert nitrogen atmosphere for 60 minutes.

[0044] Furthermore, the obtained graphene composite high entropy metal oxide coated titanium electrode was applied to electrocatalytic industrial wastewater treatment, the concentration of organic pollutants in the industrial wastewater was 20000ppm, the anode was a graphene composite high entropy metal oxide coated titanium electrode, the cathode was a porous titanium plate, the distance between the positive and negative electrodes was 1cm, the power supply was a DC power supply, and the current density was 30mA / cm 2 The results are listed in Table 1.

[0045] Comparative Example:

[0046] In order to compare the electrocatalytic effect of the prepared graphene composite high entropy metal oxide coated titanium electrode, an untreated titanium substrate was used as an anode, a porous titanium plate was used as a cathode, and other conditions were kept the same as in Example 2 to electrocatalytically degrade organic pollutants in industrial wastewater. The results are listed in Table 1.

[0047] Figure 1-3 The scanning electron microscope image of the graphene composite high entropy metal oxide coated titanium electrode prepared in Example 1-3 shows that the formed graphene composite high entropy metal oxide coating is evenly distributed and well coated on the titanium metal substrate, laying the foundation for excellent electrocatalytic performance.

[0048] Table 1 Experimental results of embodiments and comparative examples

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

[0050] As can be seen from the above table, the preparation method of the graphene composite high entropy metal oxide coated titanium electrode provided by the present invention can effectively treat organic pollutants in industrial wastewater, and the COD removal rate is above 90%. The composite electrode provided by the present invention has the advantages of simple and reliable preparation method, easy industrial production, high electrocatalytic oxidation performance, and good application prospects.

[0051] The embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments. Even if various changes are made to the present invention, if these changes fall within the scope of the claims of the present invention and their equivalents, they still fall within the protection scope of the present invention.

Claims

1. A method for preparing a graphene composite high entropy metal oxide coating titanium-based electrode, characterized in that: The following steps are involved: S1: pre-treating the titanium substrate; S2: placing the pretreated titanium substrate in an electrodeposition solution, wherein the electrodeposition solution is a mixture of a graphene oxide solution and a high entropy metal salt solution; S3: Electrodeposition is performed on the titanium substrate using the titanium substrate as the anode and the graphite electrode as the cathode; S4: heat treating the titanium substrate on which the coating is deposited in an inert gas atmosphere.

2. The method for preparing a graphene composite high entropy metal oxide coating titanium-based electrode according to claim 1, characterized in that: 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 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, and the mixture is mixed evenly to form an electrodeposition solution.

3. The method for preparing a graphene composite high entropy metal oxide coating titanium-based electrode according to claim 1, characterized in that: The step S3 is specifically as follows: a titanium electrode is used as an anode and a graphite electrode is used as a cathode. The anode-cathode area ratio is 1:

1. The distance between the two electrodes is 2 cm. The electrodeposition process parameters are as follows: a deposition current density of 0.2-1.8 A / cm 2 , the operating temperature is 30-60℃ and the deposition time is 70-200min.

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

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

6. A graphene composite high entropy metal oxide coating 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 to 5, characterized in that: It is used as anode for electrocatalytic treatment of organic pollutants in industrial wastewater.

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

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