A method for preparing a titanium-based noble metal anode by cathodic plasma electrolytic deposition and the preparation method

Abstract

The present invention discloses a method for preparing a titanium-based noble metal anode by cathodic plasma electrolytic deposition and the preparation method. The anode includes a titanium substrate and a noble metal oxide coating on its surface. The surface of the titanium substrate has a certain roughness and no oxide layer. The thickness of the noble metal oxide coating is 0.5 - 10 μm, and the iridium-tantalum ratio is 1:9 - 9:1. The preparation method is as follows: Step 1: Pretreat the titanium substrate; Step 2: Prepare the electrolyte; Step 3: Use the titanium substrate pretreated in Step 1 as the cathode, connect a platinum sheet to the positive electrode as the anode, immerse the anode and cathode in the electrolytic solution in Step 2, and perform electrolytic deposition to finally obtain an iridium-tantalum oxide anode. The present invention, while preparing an oxide carrier on the metal surface by a one-step method, enables the noble metal to be simultaneously loaded in the oxide coating, and uses the energy released by the micro-arc generated by the voltage to perform sintering during the electro-deposition process, avoiding repeated brushing and sintering; it has the characteristics of simple operation and high process efficiency.

Description

Technical Field

[0001] The present invention belongs to the technical field of preparing noble metal oxide coatings on the surface of a titanium metal substrate, and particularly relates to a cathode plasma electrolytic deposition method for preparing a titanium-based noble metal anode and a preparation method thereof. Background Art

[0002] Cathode plasma electrolytic deposition technology is a new surface treatment method for preparing coatings, which is developed from traditional electrolysis technology. When an electrolytic cell is energized, ions in the solution will move directionally towards the anode and cathode under the action of an electric field, and electrode reactions will occur. When the applied voltage reaches a certain critical point, a continuous gas film will form near the cathode, and this gas film will be broken down to generate plasma. By means of the energy of the plasma, the product that has been electro-deposited on the cathode surface is sintered. During this process, a series of complex physical and chemical reactions will occur, and finally a coating is formed.

[0003] Cathode plasma electrolytic deposition technology has attracted extensive research by scholars because it is not affected by the shape of the substrate and does not require the specimen to be a valve metal like anodic micro-arc oxidation. The composition of the coating comes from the solution, so the composition and phase structure of the coating can be controlled by changing the composition of the electrolyte. Moreover, this method has the advantages of simple operation, high process efficiency, easy doping, etc., and is widely used in the fields of coating preparation and surface modification. At present, cathode plasma electrolytic deposition technology is widely used in the preparation of metal coatings, ceramic coatings, preparation of nano-microspheres, surface cleaning, etc. Since the composition of the coating comes from the solution, a carrier coating loaded with a catalyst can be prepared by changing the solution system at the same time.

[0004] The electrodeposition method requires multiple steps of operation, such as reducing metal ions to metals by the action of an external electric field and then sintering them to form oxides, resulting in a cumbersome process. For example, as described in the literature "The durability of the thermally decomposed IrO2-Ta2O5 coated titanium anode in a sulfate solution" and "Ti electrodes prepared by electrodeposition from different Ir:Ta ratios for the degradation of polycyclic aromatic hydrocarbons", the preparation of noble metal anodes requires multiple electrodepositions and sinterings, which takes a long time and the process is quite cumbersome.

[0005] Patent application CN114592218A provides a titanium-based anode and its preparation method and application. Through a special oxide coating design, the service life of the titanium-based anode can be significantly extended, its oxygen evolution potential can be reduced, its loadable current intensity and acid resistance can be improved; however, repeated brushing and sintering are required, and the process is relatively complex. Summary of the Invention

[0006] In order to overcome the defects existing in the above-mentioned prior art, the purpose of the present invention is to provide a method for preparing a titanium-based noble metal anode by cathode plasma electrolytic deposition and its preparation method. While preparing an oxide carrier on the metal surface by a one-step method, noble metals are simultaneously loaded into the oxide coating, and the energy released by the micro-arc generated by the voltage is used for sintering during the electro-deposition process, avoiding repeated brushing and sintering; it has the characteristics of simple operation and high process efficiency.

[0007] In order to achieve the above purpose, the technical solution adopted by the present invention is:

[0008] A method for preparing a titanium-based noble metal anode by cathode plasma electrolytic deposition, and this noble metal anode has electrocatalytic performance.

[0009] A method for preparing a titanium-based noble metal anode by cathode plasma electrolytic deposition, including a titanium substrate and a noble metal oxide coating on its surface. The surface of the titanium substrate has a certain roughness and no oxide scale; the thickness of the noble metal oxide coating is 0.5 - 10 um, and the iridium-tantalum ratio is 1:9 - 9:1.

[0010] A method for preparing a titanium-based noble metal anode by cathode plasma electrolytic deposition, including the following steps;

[0011] Step 1: Pretreat the titanium substrate;

[0012] Step 2: Prepare the electrolyte: Weigh a substance containing an iridium source and dissolve it in an organic solvent, stir at room temperature until completely dissolved, weigh a certain amount of a substance containing a tantalum source and dissolve it in the organic solvent containing the iridium source, stir at room temperature until completely dissolved, and add 3 - 6 g of sodium chloride as a conductive agent;

[0013] Step 3: Connect the titanium substrate pretreated in Step 1 to the negative electrode of the power supply through a wire as the cathode, and connect the positive electrode to a platinum sheet as the anode. Immerse the anode and cathode into the electrolytic solution in Step 2 for electro-deposition to finally obtain an iridium-tantalum oxide anode.

[0014] The pretreatment of the titanium substrate in Step 1 includes surface degreasing and sandblasting treatment, and the sandblasting treatment is carried out until the surface roughness Ra < 15 um.

[0015] The sandblasted titanium substrate in Step 1 is subjected to thermal straightening treatment.

[0016] In step 1, the shaped titanium substrate is immersed in dilute hydrochloric acid with a volume concentration of 3-15% for 8-24 hours, and then boiled in an oxalic acid solution with a volume concentration of 5-10% for 0.5-3 hours. The titanium substrate is then cleaned and dried.

[0017] The iridium source in step 2 is selected from any one of chloroiridic acid, iridium trichloride, and bromoiridic acid.

[0018] The tantalum source in step 2 is selected from any one of tantalum pentachloride n-butanol solution, tantalum butanediol, and tantalum ethanol.

[0019] The organic solvent in step 2 is selected from any one of n-butanol, isopropanol, and ethanol, or any mixture thereof in any ratio.

[0020] In step 2, the iridium source, tantalum source, and organic solvent are in any ratio.

[0021] The specific limiting conditions for the electrolytic deposition in step 3 are as follows: the voltage increase rate is 1 V / s, the final voltage range is between 120 V and 180 V, the frequency is 2000 Hz, the duty cycle is 80%, and the deposition time is 3-20 minutes.

[0022] In step 3, the actual anode-cathode area ratio of conduction is less than 1:2, and the distance between the anode and the cathode is 3-7 cm.

[0023] Advantages of the present invention:

[0024] The present invention prepares a noble metal oxide coating by using the method of cathode plasma electrolytic deposition, reducing the procedures of repeated coating and sintering, reducing the complexity of the process, and being able to prepare oxide coatings with different thicknesses in a short time; in addition, the composition and phase of the oxide coating can be changed by adjusting the components in the electrolyte, thereby changing the catalytic activity of the noble metal oxide.

[0025] Hydrogen and oxygen are respectively precipitated on the surfaces of the cathode and anode in the solution, and the ratio of the precipitated gases is 2:1. Therefore, the critical value of the area ratio is equal to 2. When the anode-cathode area ratio is less than the critical value, the discharge phenomenon occurs at the cathode, and a large number of bubbles are generated on the cathode surface to form a closed gas sheath layer. When the electric field strength exceeds the critical breakdown field strength of the gas, the gas sheath layer begins to be breakdown discharged. After the gas sheath layer is broken down, the cathode overpotential is mainly concentrated on the tantalum pentoxide ceramic coating, and the electric field strength acting on the tantalum pentoxide ceramic coating increases. In addition, a large amount of heat is generated during the plasma discharge breakdown, and the mixed metal oxide coating of iridium dioxide and tantalum pentoxide is sintered to form an oxide. Description of the drawings

[0026] Figure 1 It is a schematic diagram of the principle simulation of the cathode plasma electrolytic deposition adopted by the present invention.

[0027] Figure 2 Schematic diagram of current density and voltage curves during the cathode plasma electrolytic deposition process of the present invention. Specific embodiments

[0028] The present invention will be further described in detail below with reference to the accompanying drawings.

[0029] A titanium-based noble metal anode prepared by cathode plasma electrolytic deposition, and the noble metal anode has electrocatalytic performance.

[0030] A titanium-based noble metal anode prepared by cathode plasma electrolytic deposition, including a titanium substrate and a noble metal oxide coating on its surface. The surface of the titanium substrate has a certain roughness and no oxide skin; the thickness of the noble metal oxide coating is 0.5 - 10 um, and the iridium-tantalum ratio is 1:9 - 9:1.

[0031] The method for preparing a noble metal oxide anode by cathode plasma electrolytic deposition provided by the present invention. The coating of the titanium anode is prepared by the method of plasma electrolytic deposition. The specific preparation steps are as follows:

[0032] Step 1: Pretreat the titanium substrate: degrease and defat the surface of the titanium substrate, perform sandblasting, shape correction, and pickling. The sandblasting treatment is carried out until the surface roughness Ra < 15 um;

[0033] Step 2: Prepare the electrolyte: Weigh a certain amount of iridium chloride and dissolve it in a n-butanol solution, and stir at room temperature until completely dissolved; weigh a certain amount of tantalum pentachloride n-butanol solution and dissolve it in the n-butanol solvent containing iridium chloride, stir at room temperature until completely dissolved, and add 3 - 6 g of sodium chloride as a conductive agent;

[0034] Step 3: Electrolytic deposition: Connect the titanium substrate to the negative electrode of the power supply through a wire as the cathode, and connect the positive electrode to a platinum sheet as the anode. Immerse the anode and cathode in the electrolytic solution, and control the actual conduction area ratio of the anode and cathode to be less than 1:2. The distance between the anode and cathode is 3 cm; the specific limiting conditions for electrolytic deposition are: the voltage increase rate is 1 V / s, and finally reach the voltage range between 120 V - 180 V, the frequency is 2000 Hz, the duty cycle is 80%, and the deposition time is 3 - 20 min.

[0035] Example 1

[0036] This embodiment provides a titanium-based noble metal anode prepared by cathode plasma electrolytic deposition, including a titanium substrate and a noble metal oxide coating on its surface. The surface of the titanium substrate has a certain roughness and no oxide skin; the thickness of the noble metal oxide coating is 0.8 um, and the iridium-tantalum ratio is 7:3.

[0037] This embodiment provides a preparation method for preparing a noble metal anode by cathode plasma electrolytic deposition. The specific steps include:

[0038] Step 1: Pretreat the titanium substrate: Degrease and de-oil the surface of the titanium substrate, perform sandblasting, shape correction, and pickling. The sandblasting is carried out until the surface roughness Ra < 15 μm;

[0039] Step 2: Prepare the electrolyte: Weigh 40 g of iridium chloride and dissolve it in 500 ml of n-butanol solution, and stir it at room temperature (25 °C) until completely dissolved; Weigh 70 ml of tantalum pentachloride n-butanol solution and dissolve it in the n-butanol solvent containing iridium chloride, stir it at room temperature (25 °C) until completely dissolved, and add 5 g of sodium chloride as a conductive agent;

[0040] Step 3: Electrolytic deposition: Connect the titanium substrate to the negative electrode of the power supply through a wire as the cathode, and connect the positive electrode to a platinum sheet as the anode. Immerse the anode and cathode in the electrolytic solution, control the actual conduction area ratio of the anode and cathode to be less than 1:2, and the distance between the anode and cathode is 3 cm; The specific limiting conditions for electrolytic deposition are: the voltage increase rate is 1 V / s, the final voltage is 120 V, the frequency is 2000 Hz, the duty cycle is 80%, and the deposition time is 3 min.

[0041] Example 2

[0042] This example provides a titanium-based noble metal anode prepared by cathode plasma electrolytic deposition, including a titanium substrate and a noble metal oxide coating on its surface. The surface of the titanium substrate has a certain roughness and no oxide scale; the thickness of the noble metal oxide coating is 1 μm, and the iridium-tantalum ratio is 7:3.

[0043] This example provides a preparation method for preparing a noble metal anode by cathode plasma electrolytic deposition. The specific steps include:

[0044] Step 1: Pretreat the titanium substrate: Degrease and de-oil the surface of the titanium substrate, perform sandblasting, shape correction, and pickling. The sandblasting is carried out until the surface roughness Ra < 15 μm;

[0045] Step 2: Prepare the electrolyte: Weigh 40 g of iridium chloride and dissolve it in 500 ml of n-butanol solution, and stir it at room temperature (25 °C) until completely dissolved; Weigh 70 ml of tantalum pentachloride n-butanol solution and dissolve it in the n-butanol solvent containing iridium chloride, stir it at room temperature (25 °C) until completely dissolved, and add 5 g of sodium chloride as a conductive agent;

[0046] Step 3: Electrolytic deposition: Connect the titanium substrate to the negative electrode of the power supply through a wire as the cathode, and connect the positive electrode to a platinum sheet as the anode. Immerse the anode and cathode in the electrolytic solution, control the actual conduction area ratio of the anode and cathode to be less than 1:2, and the distance between the anode and cathode is 3 cm; The specific limiting conditions for electrolytic deposition are: the voltage increase rate is 1 V / s, the final voltage is 180 V, the frequency is 2000 Hz, the duty cycle is 80%, and the deposition time is 5 min.

[0047] Example 3

[0048] This embodiment provides a titanium-based noble metal anode prepared by cathodic plasma electrolytic deposition, including a titanium substrate and a noble metal oxide coating on its surface. The surface of the titanium substrate has a certain roughness and no oxide scale; the thickness of the noble metal oxide coating is 2 μm, and the iridium-tantalum ratio is 7:3.

[0049] This embodiment provides a preparation method for preparing a noble metal anode by cathodic plasma electrolytic deposition. The specific steps include:

[0050] Step 1: Pretreat the titanium substrate: Degrease and defat the surface of the titanium substrate, perform sandblasting, shape correction, and pickling. The sandblasting is carried out until the surface roughness Ra < 15 μm;

[0051] Step 2: Prepare the electrolyte: Weigh 40 g of iridium chloride and dissolve it in 500 ml of n-butanol solution, and stir until completely dissolved at room temperature (25 °C); weigh 70 ml of tantalum pentachloride n-butanol solution and dissolve it in the n-butanol solvent containing iridium chloride, stir until completely dissolved at room temperature (25 °C), and add 5 g of sodium chloride as a conductive agent;

[0052] Step 3: Electrolytic deposition: Connect the titanium substrate to the negative electrode of the power supply through a wire as the cathode, and connect the positive electrode to a platinum sheet as the anode. Immerse the anode and cathode in the electrolytic solution, and control the actual conduction area ratio of the anode and cathode to be less than 1:2. The distance between the anode and cathode is 3 cm; the specific limiting conditions for electrolytic deposition are: the voltage increase rate is 1 V / s, the final voltage is 150 V, the frequency is 2000 Hz, the duty cycle is 80%, and the deposition time is 10 min.

[0053] Example 4

[0054] This embodiment provides a titanium-based noble metal anode prepared by cathodic plasma electrolytic deposition, including a titanium substrate and a noble metal oxide coating on its surface. The surface of the titanium substrate has a certain roughness and no oxide scale; the thickness of the noble metal oxide coating is 3.5 μm, and the iridium-tantalum ratio is 7:3.

[0055] This embodiment provides a preparation method for preparing a noble metal anode by cathodic plasma electrolytic deposition. The specific steps include:

[0056] Step 1: Pretreat the titanium substrate: Degrease and defat the surface of the titanium substrate, perform sandblasting, shape correction, and pickling. The sandblasting is carried out until the surface roughness Ra < 15 μm;

[0057] Step 2: Prepare the electrolyte: Weigh 40 g of iridium chloride and dissolve it in 500 ml of n-butanol solution, and stir until completely dissolved at room temperature (25 °C); weigh 70 ml of tantalum pentachloride n-butanol solution and dissolve it in the n-butanol solvent containing iridium chloride, stir until completely dissolved at room temperature (25 °C), and add 5 g of sodium chloride as a conductive agent;

[0058] Step 3: Electrolytic deposition: Connect the titanium substrate to the negative electrode of the power supply through a wire as the cathode, and connect the positive electrode to a platinum sheet as the anode. Immerse the anode and cathode in the electrolytic solution, control the actual conduction area ratio of the anode and cathode to be less than 1:2, and the distance between the anode and cathode is 3 cm; the specific limiting conditions for electrolytic deposition are: the voltage increase rate is 1 V / s, the final voltage is 150 V, the frequency is 2000 Hz, the duty cycle is 80%, and the deposition time is 15 min.

[0059] Example 5

[0060] This embodiment provides a titanium-based noble metal anode prepared by cathode plasma electrolytic deposition, including a titanium substrate and a noble metal oxide coating on its surface. The surface of the titanium substrate has a certain roughness and no oxide skin; the thickness of the noble metal oxide coating is 5 μm, and the iridium-tantalum ratio is 7:3.

[0061] This embodiment provides a preparation method for preparing a noble metal anode by cathode plasma electrolytic deposition, specifically including:

[0062] Step 1: Pretreat the titanium substrate: Degrease, degrease, sandblast, shape, and pickling the surface of the titanium substrate. The sandblasting treatment is carried out until the surface roughness Ra < 15 μm;

[0063] Step 2: Prepare the electrolyte: Weigh 40 g of iridium chloride and dissolve it in 500 ml of n-butanol solution, and stir until completely dissolved at room temperature (25 °C); weigh 70 ml of tantalum pentachloride n-butanol solution and dissolve it in the n-butanol solvent containing iridium chloride, stir until completely dissolved at room temperature (25 °C), and add 5 g of sodium chloride as a conductive agent;

[0064] Step 3: Electrolytic deposition: Connect the titanium substrate to the negative electrode of the power supply through a wire as the cathode, and connect the positive electrode to a platinum sheet as the anode. Immerse the anode and cathode in the electrolytic solution, control the actual conduction area ratio of the anode and cathode to be less than 1:2, and the distance between the anode and cathode is 3 cm; the specific limiting conditions for electrolytic deposition are: the voltage increase rate is 1 V / s, the final voltage is 150 V, the frequency is 2000 Hz, the duty cycle is 80%, and the deposition time is 20 min.

[0065] As Figure 1 , Figure 2Shown as follows: The cross-sectional thickness of the noble metal anode prepared by the preparation methods provided in Examples 1-5 and the change of oxygen evolution potential in a 1 mol / L sulfuric acid system are as follows in the table:

[0066] Example 1 Example 2 Example 3 Example 4 Example 5 Thickness 0.8um 1um 2um 3.5um 5um Oxygen evolution potential 1.374V 1.379V 1.382V 1.384V 1.385V

[0067] Based on the test data of the thickness and oxygen evolution potential in the above examples, an iridium-tantalum anode with electrocatalytic performance was successfully prepared. After testing, compared with the prior art, the noble metal anode prepared by the present invention has the advantages of being fast, simple, and easy to operate in preparing the electrocatalytically active noble metal anode.

[0068] In summary, the method for preparing a noble metal anode by cathode plasma electrolytic deposition according to the present invention applies a large voltage across the cathode and anode, thereby generating micro-arcs and releasing a large amount of energy. Sintering is carried out during the electro-deposition process, and with the extension of the electrolysis time, the thickness of the coating gradually increases. The preparation of the noble metal anode by a one-step method avoids cumbersome processes, and at the same time, the change of the composition of the oxide coating can be achieved by changing the composition of the electrolyte. The production efficiency of the anode is improved, and it can better meet the market demand.

Claims

1. A preparation method for preparing a titanium-based noble metal anode by cathode plasma electrolytic deposition, characterized in that, It includes the following steps; Step 1: Pretreat the titanium substrate; Step 2: Prepare the electrolyte: Weigh the substance containing the iridium source and dissolve it in an organic solvent, stir at room temperature until completely dissolved, weigh a certain amount of the substance containing the tantalum source and dissolve it in the organic solvent containing the iridium source, stir at room temperature until completely dissolved, and add 3 - 6 g of sodium chloride thereto; Step 3: Connect the titanium substrate pretreated in Step 1 to the negative electrode of the power supply through a wire as the cathode, connect the positive electrode to a platinum sheet as the anode, immerse the anode and cathode into the electrolytic solution in Step 2, and perform electrolytic deposition to finally obtain an iridium tantalum oxide anode; The specific limiting conditions for the electrolytic deposition in Step 3 are: the voltage increase rate is 1 V / s, and finally the voltage ranges between 120 V and 180 V.

2. The preparation method of a titanium-based noble metal anode prepared by cathode plasma electrolytic deposition according to claim 1, characterized in that, The pretreatment of the titanium substrate in Step 1 includes surface degreasing and sandblasting treatment, and the sandblasting treatment is carried out until the surface roughness Ra < 15 μm; In Step 1, the sandblasted titanium substrate is subjected to thermal shape correction treatment; In Step 1, the shaped titanium substrate is soaked in dilute hydrochloric acid with a volume concentration of 3 - 15% for 8 - 24 h, and then boiled in an oxalic acid solution with a volume concentration of 5 - 10% for 0.5 - 3 h, and the titanium substrate is cleaned and dried.

3. A preparation method of a titanium-based noble metal anode by cathode plasma electrolytic deposition according to claim 1, characterized in that, The iridium source in Step 2 is selected from any one of iridium chlorate, iridium trichloride, and iridium bromate.

4. A preparation method for a titanium-based noble metal anode prepared by cathode plasma electrolytic deposition according to claim 1, characterized in that, The tantalum source in Step 2 is selected from any one of tantalum pentachloride n - butanol solution, tantalum butanediol, and tantalum ethanol.

5. The preparation method of a titanium-based noble metal anode prepared by cathode plasma electrolytic deposition according to claim 1, characterized in that, The organic solvent in Step 2 is selected from any one of n - butanol, isopropanol, and ethanol or any ratio mixture thereof.

6. The preparation method of a titanium-based noble metal anode prepared by cathode plasma electrolytic deposition according to claim 1, characterized in that, In Step 2, the ratio between the iridium source, the tantalum source, and the organic solvent is arbitrary.

7. The preparation method of a titanium-based noble metal anode prepared by cathode plasma electrolytic deposition according to claim 1, characterized in that, The specific limiting conditions for the electrolytic deposition in Step 3 are: the frequency is 2000 Hz, the duty cycle is 80%, and the deposition time is 3 - 20 min.

8. The preparation method of a titanium-based noble metal anode prepared by cathode plasma electrolytic deposition according to claim 1, characterized in that, In Step 3, the actual conduction area ratio of the anode and cathode is less than 1:2, and the distance between the anode and cathode is 3 - 7 cm.

9. A titanium-based noble metal anode prepared by cathode plasma electrolytic deposition obtained by the method according to any one of claims 1-8, characterized in that, This noble metal anode has electrocatalytic performance.

10. A titanium-based noble metal anode prepared by cathode plasma electrolytic deposition according to claim 9, characterized in that, It includes a titanium substrate and a noble metal oxide coating on its surface. The surface of the titanium substrate has a certain roughness and no oxide skin; the thickness of the noble metal oxide coating is 0.5 - 10 μm, and the iridium tantalum ratio is 1:9 - 9:1.

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