Preparation method of DSA electrode

Abstract

The invention belongs to the field of electrocatalytic oxidation, and provides a preparation method of a DSA electrode. The method comprises the following steps: pretreating a DSA matrix; electrically depositing a tin layer; preparing porous foamed tin; the foamed tin is subjected to anodic oxidation; and modifying with nanoparticles to obtain the DSA electrode. The SnO2-based composite coating DSA electrode is prepared by adopting an electrodeposition combined active particle modification technology, and the method is simple in process and does not have tedious coating and sintering processes; no traditional organic solvent is used, and no related waste gas and waste liquid pollution exists; the surface appearance of the active layer is controllable, and the binding force is good; the usage amount of precious metal is reduced, and the cost is low.

Description

Technical Field

[0001] The present invention belongs to the field of electrocatalytic oxidation and relates to a preparation method of a DSA electrode. Background Art

[0002] With the rapid development of modern industry, the discharge of industrial wastewater is increasing day by day, and its composition is becoming more and more complex. Many industrial wastewaters contain a large amount of harmful substances such as refractory organic pollutants and heavy metal ions, posing a serious threat to the environment and human health. Traditional water treatment methods are often difficult to effectively remove these pollutants, so it is necessary to develop efficient and new water treatment technologies. As an advanced oxidation technology, electrocatalytic oxidation technology can generate strongly oxidizing free radicals, such as hydroxyl radicals (·OH), which can degrade organic pollutants into harmless substances such as carbon dioxide and water, and has broad application prospects in the field of wastewater treatment. And the DSA electrode, as a key component in the electrocatalytic oxidation process, its performance directly affects the treatment effect and efficiency of electrocatalytic oxidation technology.

[0003] DSA electrodes usually use titanium and its alloys or stainless steel as the substrate material, and a layer of electrocatalytically active noble metal oxide coating (such as oxides of elements such as Au, Ag, Pt, etc.) or transition metal oxide coating (such as oxides of elements such as Sn, Mn, Pb, etc.) is coated on the substrate surface. Existing preparation methods of DSA electrodes include thermal decomposition method, sol-gel method, electrochemical deposition method, chemical vapor deposition method, pulsed laser deposition method, etc. For example, the patent with the publication number CN109292918A introduces a preparation method of a DSA electrode. This method coats the electrode by physical means such as spin coating or dipping through noble metal loading, and then is sintered into shape. However, this method has many drawbacks: the cost of the electrode is high; the bonding force between the electrode and the substrate is poor; the manufacturing process flow is long and complicated; and the organic solvents used are volatile, which will cause serious pollution to the environment and the working environment of workers. The patent with the publication number CN113562815A discloses a preparation method of a composite coating DSA electrode for water treatment. This electrode uses electro-deposition fusion of nanoparticles technology to prepare a composite coating DSA electrode, reducing organic matter in wastewater and solving the problem of generating VOCs during preparation, but an electro-deposited intermediate layer is required and the preparation process is complex. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to solve the problems of easy generation of organic solvent pollution, high price of electrode materials, and complicated process during the preparation of existing DSA electrodes.

[0005] The technical solution of the present invention:

[0006] A preparation method of a DSA electrode, the steps are as follows:

[0007] (1) Substrate pretreatment: Pretreat the metal substrate to obtain a metal substrate with no oil stains and other impurities on its surface;

[0008] (2) Electro-deposition of tin layer: Use a two-electrode system to electro-deposit a tin layer on the surface of the metal substrate. Take the pretreated metal substrate obtained in step (1) as the cathode, a tin sheet as the anode. The formulation of the plating solution is 40 - 60 g / L of tin salt and 50 - 70 g / L of complexing agent. Under the conditions of a water bath temperature of 20 - 30 °C, a rotation speed of 200 - 400 rpm, and a current density of 6 - 15 mA / cm 2 , the electro-deposition time is 10 - 30 min to obtain a metal substrate deposited with a tin layer;

[0009] (3) Preparation of tin foam by hydrogen bubble template method: Use a three-electrode system to prepare tin foam. Take the metal substrate deposited with a tin layer obtained in step (2) as the working electrode, a platinum sheet as the counter electrode, and a saturated calomel electrode as the reference electrode. In a 0.02 - 0.2 mol / L SnCl2 and 0.5 - 2 mol / L H2SO4 solution, control the potential to be -1.5~-2 V (vs. SCE), the water bath temperature to be 20 - 30 °C, and the time to be 20 - 40 s to prepare a tin foam layer on the surface of the tin layer, which is a tin foam layer - tin layer - metal substrate;

[0010] (4) Anodic oxidation of the tin foam layer: Use a two-electrode system to prepare anodized tin foam. Take the tin foam - tin layer - metal substrate obtained in step (3) as the anode and a graphite sheet as the cathode. In a 0.1 - 3 mol / L NaOH solution, under the conditions of controlling the water bath temperature to be 20 - 30 °C, the voltage to be 3 - 8 V, and the anodic oxidation time to be 5 - 10 min, anodize the tin foam layer in the tin foam - tin layer - metal substrate to obtain an anodized tin foam layer - tin layer - metal substrate;

[0011] (5) Modification with active particles: Modify nano-particles on the anodized tin foam layer.

[0012] Preferably, the specific process of the pretreatment in step (1) is: mechanically polish, degrease, acid-activate, and wash the metal substrate. First, mechanically polish the metal substrate successively with 400#, 800#, and 1200# SiC water sandpapers. Then put the polished metal substrate into a 1 - 6 mol / L NaOH solution and ultrasonicate for 10 - 20 min (temperature is 20 - 30 °C). Then put the alkali-washed metal substrate into a hydrochloric acid (concentration is 3 mol / L): hydrofluoric acid (concentration is 1 mol / L) solution with a volume ratio of 30:l and soak for 10 - 15 min. Finally, rinse the acid-activated metal substrate with deionized water and dry it with cold air.

[0013] Preferably, the tin salt used in step (2) is one or more of stannous chloride, stannous sulfate, stannous pyrophosphate, and stannous oxide.

[0014] Preferably, the complexing agent used in step (2) is one or more of sodium citrate, ammonium citrate, and potassium pyrophosphate.

[0015] Preferably, the nanoparticles in step (5) are one or more of lead, lead oxides, rare earth metals, iridium, and ruthenium.

[0016] Preferably, the lead precursor salt used in step (5) is one or more of lead methyl sulfonate, lead aminosulfonate, lead sulfate, lead nitrate, and lead carbonate.

[0017] Preferably, the precursor salts of rare earth elements used in step (5) are one or more of cerium sulfate, cerium nitrate, cerium chloride, lanthanum sulfate, lanthanum nitrate, lanthanum chloride, scandium sulfate, and scandium oxalate.

[0018] Preferably, the iridium precursor salt used in step (5) is one or more of potassium hexachloroiridate, ammonium hexachloroiridate, iridium sulfate, and iridium nitrate.

[0019] Preferably, the ruthenium precursor salt used in step (5) is one or more of ruthenium chloride, ruthenium nitrate, ruthenium sulfate, and ruthenium acetate.

[0020] The beneficial effects of the present invention are as follows: The present invention provides a method for preparing a DSA electrode by electro-deposition combined with active particle modification, which has a simple process, good bonding force between the activation layer and the metal substrate, and no organic solvent pollution in the production process; the foam tin layer prepared by the hydrogen bubble template method has a micron-scale porous structure, and anodic oxidation of the foam tin layer can in-situ prepare tin oxide with a nano-morphology on the foam tin skeleton. The micro-nano hierarchical structure formed based on this has a high specific surface area, and the active sites of the electrode can fully contact and react with the reactants in the test solution, improving the catalytic efficiency of the electrode; at the same time, this electrode greatly reduces the usage of precious metals, solves the problem of the high price of precious metal oxide coatings, and reduces the production cost. Description of the Drawings

[0021] Figure 1 It is the surface morphology diagram of Example 1.

[0022] Figure 2 It is the surface morphology diagram of Example 2.

[0023] Figure 3 It is the surface morphology diagram of Example 3.

[0024] Figure 4 It is the surface morphology diagram of Example 4.

[0025] Figure 5 It is the surface topography diagram of Example 5.

[0026] Figure 6 It is the surface topography diagram of Example 6.

[0027] Figure 7 It is the surface topography diagram of Example 7.

[0028] Figure 8 It is the surface topography diagram of Example 8.

[0029] Figure 9 It is the surface topography diagram of Example 9.

[0030] Figure 10 It is the surface topography diagram of Example 10. Specific Embodiments

[0031] The following further illustrates the specific embodiments of the present invention in combination with the accompanying drawings and technical solutions. The embodiments described in the present invention are only for the purpose of illustrating the present invention and do not limit the scope of the present invention.

[0032] Example 1

[0033] A preparation method of a DSA electrode, comprising the following steps:

[0034] (1) Pretreatment of the substrate: Mechanically polish the metal substrate successively with 400#, 800#, and 1200# SiC sandpapers to form a surface with a certain roughness; after rinsing the polished metal substrate with deionized water, put it into a 6 mol / L NaOH solution and ultrasonically treat it for 20 min (temperature is 25 °C) for degreasing treatment; after rinsing the degreased metal substrate with deionized water, soak it in a hydrochloric acid (concentration is 3 mol / L): hydrofluoric acid (concentration is 1 mol / L) solution with a volume ratio of 30:1 for 10 min for pickling treatment to remove the oxide film on the substrate surface; rinse the pickled metal substrate with deionized water and dry it with cold air for standby.

[0035] (2) Electro-deposition of a tin layer: Use the metal substrate treated in step (1) as the cathode and a pure tin sheet as the anode for electro-depositing tin; the main components of the electro-deposition solution are: 40 g / L stannous chloride, 75 g / L sodium citrate; the process parameters are: temperature is 25 °C, rotation speed is 200 rpm, the distance between the two electrodes is 1 cm, and the current density is 10 mA / cm 2 , and the electro-deposition time is 10 min.

[0036] (3) Preparation of foamed tin: Using the sample obtained in step (2) as the working electrode, a platinum sheet as the counter electrode, and a saturated calomel electrode as the reference electrode to prepare foamed tin; the main components of the solution are: 0.04 mol / L SnCl2, 1.5 mol / L H2SO4; the process parameters are: the temperature is 25 °C, the distance between the working electrode and the counter electrode is about 2 cm, the potential is -1.7 V (vs. SCE), and the time is 30 s.

[0037] (4) Anodic oxidation of the foamed tin layer: Using the metal substrate with the foamed tin layer surface in step (3) as the anode and a graphite sheet as the cathode for anodic oxidation; the solution composition is: 1 mol / L NaOH; the process parameters are: the temperature is 25 °C, the distance between the two electrodes is about 2 cm, the oxidation voltage is 5 V, and the oxidation time is 5 min.

[0038] (5) Electrodeposition of nanoparticles: Using the anodic oxidized foamed tin layer obtained in step (4) as the cathode and a graphite sheet as the anode for electrodeposition; the plating solution composition is 15 g / L lead methyl sulfonate, 0.02 mol / L cerium sulfate, 0.1 mol / L H2SO4, 1 mol / L citric acid; the water bath temperature is 25 °C, the current density is 4 A / dm 2 , and the deposition time is 5 min. The surface morphology of the obtained sample is as Figure 1 shown.

[0039] Example 2

[0040] The preparation method of this example is the same as that of Example 1, except that the tin salt in the step of electrodepositing the tin layer is 40 g / L stannous sulfate. The surface morphology of the obtained sample is as Figure 2 shown.

[0041] Example 3

[0042] The preparation method of this example is the same as that of Example 1, except that the concentration of SnCl2 in the step of preparing foamed tin is 0.06 mol / L, and the rare earth element salt in the step of electrodepositing nanoparticles is 0.02 mol / L lanthanum sulfate. The surface morphology of the obtained sample is as Figure 3 shown.

[0043] Example 4

[0044] The preparation method of this example is the same as that of Example 1, except that the concentration of SnCl2 in the step of preparing foamed tin is 0.06 mol / L, and the deposition time is 40 s. The surface morphology of the obtained sample is as Figure 4 shown.

[0045] Example 5

[0046] The preparation method of this example is the same as that of Example 1, except that the concentration of SnCl2 in the step of preparing tin foam is 0.08 mol / L. The surface morphology of the obtained sample is as Figure 5 shown.

[0047] Example 6

[0048] The preparation method of this example is the same as that of Example 1, except that the concentration of SnCl2 in the step of preparing tin foam is 0.08 mol / L and the deposition time is 40 s; the lead salt in the step of electrodepositing nanoparticles is 20 g / L lead sulfate. The surface morphology of the obtained sample is as Figure 6 shown.

[0049] Example 7

[0050] The preparation method of this example is the same as that of Example 1, except that the deposition voltage in the step of preparing tin foam is -2 V (vs. SCE). The surface morphology of the obtained sample is as Figure 7 shown.

[0051] Example 8

[0052] The preparation method of this example is the same as that of Example 1, except that the deposition voltage in the step of preparing tin foam is -2 V (vs. SCE) and the deposition time is 20 s. The surface morphology of the obtained sample is as Figure 8 shown.

[0053] Example 9

[0054] The preparation method of this example is the same as that of Example 1, except that the concentration of SnCl2 in the step of preparing tin foam is 0.06 mol / L, the deposition voltage is -2 V (vs. SCE), and the deposition time is 30 s. The surface morphology of the obtained sample is as Figure 9 shown.

[0055] Example 10

[0056] The preparation method of this example is the same as that of Example 1, except that the concentration of SnCl2 in the step of preparing tin foam is 0.06 mol / L, the deposition voltage is -2 V (vs. SCE), and the deposition time is 20 s. The surface morphology of the obtained sample is as Figure 10 shown.

[0057] In summary, the DSA electrode is prepared by electrodeposition combined with active particle modification in the present invention. The prepared electrode has good binding force and extremely high specific surface area, which can greatly improve the catalytic efficiency and stability; the process is simple, without complex coating and sintering processes, and the solutions in the production process are all aqueous solutions of various solvents, without organic solvent pollution; the raw material cost is low, solving the problem of the high price of noble metal oxide coatings.

[0058] The embodiments described above only represent the implementation modes of the present invention, but should not be construed as limiting the scope of the patent for the present invention. It should be noted that for those skilled in the art, without departing from the concept of the present invention, several modifications and improvements can still be made, and these all belong to the protection scope of the present invention.

Claims

1. A preparation method of a DSA electrode, characterized in that, The steps are as follows: (1) Substrate pretreatment: Pretreat the metal substrate to obtain a metal substrate with no oil and other impurities on its surface; (2) Electrodeposited tin layer: A two-electrode system is used to electrodeposit a tin layer on the surface of a metal substrate. The pretreated metal substrate obtained in step (1) is used as the cathode, and a tin sheet is used as the anode. The formulation of the plating solution is 40 - 60 g / L of tin salt and 50 - 70 g / L of complexing agent. Under the conditions of a water bath temperature of 20 - 30 °C, a rotation speed of 200 - 400 rpm, and a current density of 6 - 15 mA / cm 2 , the electrodeposition time is 10 - 30 min to obtain a metal substrate with a deposited tin layer; (3) Preparation of tin foam by hydrogen bubble template method: Prepare tin foam using a three-electrode system. Use the metal substrate deposited with a tin layer obtained in step (2) as the working electrode, a platinum sheet as the counter electrode, and a saturated calomel electrode as the reference electrode. In a 0.02 - 0.2 mol / L SnCl2 and 0.5 - 2 mol / L H2SO4 solution, control the potential to be -1.5 to -2 V, the water bath temperature to be 20 - 30 °C, and the time to be 20 - 40 s to prepare a tin foam layer on the surface of the tin layer, forming a tin foam layer - tin layer - metal substrate; (4) Anodic oxidation of the tin foam layer: Prepare anodized tin foam using a two-electrode system. Use the tin foam - tin layer - metal substrate obtained in step (3) as the anode and a graphite sheet as the cathode. In a 0.1 - 3 mol / L NaOH solution, under the conditions of controlling the water bath temperature to be 20 - 30 °C, the voltage to be 3 - 8 V, and the anodic oxidation time to be 5 - 10 min, anodize the tin foam layer in the tin foam layer - tin layer - metal substrate to obtain an anodized tin foam layer - tin layer - metal substrate; (5) Modification with active particles: Modify the anodized tin foam layer with nano-particles.

2. The preparation method of the DSA electrode according to claim 1, characterized in that, The specific process of the pretreatment in step (1) is: mechanically polish, degrease, acid-activate, and wash the metal substrate; First, mechanically polish the metal substrate successively with 400#, 800#, and 1200# SiC water sandpapers; Then, under the condition of a temperature of 20 - 30 °C, put the polished metal substrate into a 1 - 6 mol / L NaOH solution and ultrasonicate for 10 - 20 min; Next, immerse the metal substrate in a mixed solution of hydrochloric acid with a concentration of 3 mol / L and hydrofluoric acid with a concentration of 1 mol / L with a volume ratio of 30:1 for 10 - 15 min; Finally, rinse the metal substrate with deionized water and dry it with cold air.

3. The preparation method of the DSA electrode according to claim 1, wherein The tin salt used in step (2) is one or more of stannous chloride, stannous sulfate, stannous pyrophosphate, and stannous oxide.

4. The preparation method of the DSA electrode according to claim 1, characterized in that, The complexing agent used in step (2) is one or more of sodium citrate, ammonium citrate, and potassium pyrophosphate.

5. The preparation method of the DSA electrode according to claim 1, wherein The nano-particles mentioned in step (5) are one or more of lead, lead oxides, rare earth metals, iridium, and ruthenium.

6. The preparation method of the DSA electrode according to claim 5, characterized in that, The precursor salts of lead and lead oxides in step (5) are one or more of lead methanesulfonate, lead aminosulfonate, lead sulfate, lead nitrate, and lead carbonate.

7. The preparation method of the DSA electrode according to claim 5, characterized in that, The precursor salts of rare earth elements in step (5) are one or more of cerium sulfate, cerium nitrate, cerium chloride, lanthanum sulfate, lanthanum nitrate, lanthanum chloride, scandium sulfate, and scandium oxalate.

8. The preparation method of the DSA electrode according to claim 5, characterized in that, The precursor salts of iridium in step (5) are one or more of potassium hexachloroiridate, ammonium hexachloroiridate, iridium sulfate, and iridium nitrate.

9. The preparation method of the DSA electrode according to claim 5, characterized in that, The precursor salts of ruthenium in step (5) are one or more of ruthenium chloride, ruthenium nitrate, ruthenium sulfate, and ruthenium acetate.

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