阅读说明：本技术 一种钛基涂层钛阳极的制备方法 (Preparation method of titanium anode with titanium-based coating ) 是由 柴作强 郝小军 冯庆 贾波 贺斌 白璐怡 鲁海军 孟鹏帅 于 2020-12-18 设计创作，主要内容包括：本发明属于电化学技术领域,涉及一种钛基涂层钛阳极的制备方法。通过原位喷涂法,将中间层前驱体金属盐与特定溶剂混合得到底层制备前驱体溶液,将前驱体溶液喷涂到经特定预处理后的180～300℃的钛基板上,前驱体溶液发生原位热分解而形成致密的氧化物沉积层,再经高温烧结得到含氧化物中间层的钛基体,之后在钛基体表面涂覆铱钽贵金属催化层,得到铱钽氧化物涂层钛阳极。本发明采用喷涂技术结合分步原位热处理的方法制备氧化物中间层,在其表面涂刷贵金属催化层,克服了现有刷涂法和滚涂法制备的中间层不均匀而导致电极寿命短的技术缺陷。(The invention belongs to the technical field of electrochemistry, and relates to a preparation method of a titanium anode with a titanium-based coating. Mixing a precursor metal salt of the middle layer with a specific solvent by an in-situ spraying method to obtain a precursor solution for preparing the bottom layer, spraying the precursor solution on a titanium substrate which is subjected to specific pretreatment and has a temperature of 180-300 ℃, carrying out in-situ thermal decomposition on the precursor solution to form a compact oxide deposition layer, carrying out high-temperature sintering to obtain a titanium substrate containing the oxide middle layer, and then coating an iridium tantalum noble metal catalyst layer on the surface of the titanium substrate to obtain the iridium tantalum oxide coating titanium anode. The invention adopts the spraying technology and the step-by-step in-situ heat treatment method to prepare the oxide intermediate layer, and coats the noble metal catalyst layer on the surface of the oxide intermediate layer, thereby overcoming the technical defect of short service life of the electrode caused by the uneven intermediate layer prepared by the traditional brushing and rolling methods.)

1. The preparation method of the titanium anode with the titanium-based coating is characterized by comprising the following steps:

1) pretreatment of a titanium substrate: carrying out sand blasting, acid etching, cleaning and drying treatment on the surface of the titanium substrate;

2) preparation of the oxide interlayer by spray coating: controlling the temperature of the pretreated titanium substrate to be 180-300 ℃, and spraying a precursor solution onto the surface of the titanium substrate until the surface of the titanium substrate is completely covered by the precursor solution; then putting the mixture into a thermal oxidation furnace for heat preservation, and carrying out in-situ pyrolysis on the precursor solution;

3) repeating the step 2) for many times until the thickness of the oxide intermediate layer is 0.2-3 mu m, and finishing the preparation of the titanium substrate with the oxide intermediate layer;

4) preparing an iridium tantalum noble metal oxide active layer by using a brush coating method: coating a noble metal coating liquid on the surface of the titanium substrate with the oxide interlayer prepared in the step 3), and sintering; and repeatedly brushing and sintering to obtain the iridium-tantalum noble metal oxide active layer, thereby completing the preparation of the coating titanium anode.

2. The method for preparing the titanium-based coating titanium anode according to the claim 1, wherein the pretreatment in the step 1) comprises sand blasting, acid etching, cleaning and drying;

the sand mold subjected to sand blasting treatment is selected from one or more of steel sand, brown corundum, quartz sand, white corundum and Hainan sand until the surface roughness Rz is more than 25;

the acid etching solution in the acid etching treatment is 5-10% of oxalic acid solution or/and 2-20% of hydrochloric acid solution.

3. The method for preparing the titanium-based coating titanium anode according to claim 1, wherein the precursor solution in the step 2) is selected from organic solutions containing one or more salts of iridium, tin, titanium, ruthenium, tantalum, antimony, niobium, platinum, rhodium and manganese, and the total metal ion concentration is 0.1-0.5 mol/L.

4. The method for preparing titanium-based coated titanium anode according to claim 3, wherein the organic solvent used for preparing the organic solution is one or more selected from n-butanol, isopropanol and butanediol.

5. The method for preparing the titanium-based coating titanium anode according to claim 1, wherein the spraying in the step 2) is carried out by atomizing with a spray gun at a speed of 0.1-3 mL/min-m²。

6. The method for preparing the titanium-based coating titanium anode according to the claim 1, wherein the temperature of the thermal oxidation furnace in the step 2) is not lower than 480 ℃.

7. The method for preparing the titanium-based coating titanium anode according to claim 6, wherein the heat preservation temperature in the thermal oxidation furnace in the step 2) is 500-540 ℃, and the heat preservation time is 10-120 min.

8. The method for preparing titanium-based coated titanium anode according to claim 1, wherein the noble metal coating liquid in the step 4) is prepared from iridium compound, TaCl₅N-butyl alcohol solution and solvent; the iridium source in the iridium compound is selected from H₂IrCl₆、IrCl₃、K₂IrCl₆、H₂IrBr₆The solvent is one or more selected from ethylene glycol, n-butanol, isopropanol, propanol, ethanol and butanediol.

9. The method for preparing the titanium-based coating titanium anode according to claim 8, wherein the molar ratio of iridium to tantalum in the noble metal masking liquid is (0.3-1): (0-1), the concentration of total metal ions is controlled to be 0.01-0.5 mol/L.

10. The method for preparing the titanium-based coating titanium anode according to claim 1, wherein the sintering temperature in the step 4) is 450-540 ℃, the thermal oxidation time is 10-30 min each time, and the final sintering time is 1-2 h.

Technical Field

The invention belongs to the technical field of electrochemistry, and relates to a preparation method of a titanium anode with a titanium-based coating.

Background

The titanium anode is also called metal oxide electrode, which is a novel insoluble electrode with valve type metal titanium as a matrix and noble metal oxide coated on the surface. The anode can be divided into an oxygen evolution anode and a chlorine evolution anode according to different catalytic coatings on the surface of the anode. Wherein, IrO₂-Ta₂O₅the/Ti anode has the advantages of small polarization, extremely low consumption rate, high conductivity, low oxygen evolution potential, strong corrosion resistance, long service life, excellent electrocatalytic activity and the like, and is widely applied to the fields of electrolytic copper foil, electroplating, hydrometallurgy, sewage treatment and the like. Because the traditional noble metal anode active layer has low adhesive force on the titanium matrix and is easy to peel off, the service life is short in the electrolytic process. To solve this problem, it is common practice to introduce an intermediate layer between the titanium substrate and the active catalytic layer; the middle layer can better combine the catalyst layer on the matrix, and can effectively relieve the corrosion of the titanium matrix and delay the TiO on the surface of the titanium substrate₂The generation of the passive film is beneficial to preventing the anode from losing efficacy.

The intermediate layer is usually prepared by two methods, namely, an immersion thermal decomposition method and a sol-gel method. In order to obtain the actual use effect, the dipping thermal decomposition method usually needs a plurality of brushing-drying-sintering processes, the actual service life requirement can be met only when the coating reaches a certain thickness, and therefore, the consumption of the noble metal is large and the cost is high. In the sol-gel method, the anode production process must be carried out by pretreatment processes such as oil removal, sand blasting, acid etching and the like, so that the surface of the titanium substrate is roughened to form an uneven pitted surface. Therefore, when the intermediate layer is coated on the pretreated titanium substrate by adopting the two methods, the coating is uneven due to serious material accumulation of a sand blasting pit or an acid etching pit, the material accumulation at the pit is serious, the intermediate layer is thick, and the salient points are relatively thin, so that the current at the position of the salient point is concentrated in the use process of the anode, the active layer in the area is preferentially dissolved and falls off, and finally the anode is caused to fail.

Disclosure of Invention

The invention aims to overcome the defects of the prior art and provide a preparation method of a titanium-based coating titanium anode, wherein an intermediate layer with uniform thickness is prepared between a titanium substrate and an iridium tantalum active layer, and an iridium tantalum catalytic layer is coated on the surface of the intermediate layer, so that the catalytic activity of the anode is effectively improved, and the service life of the anode is effectively prolonged.

In order to achieve the purpose, the invention provides the following technical scheme:

the preparation method of the titanium anode with the titanium-based coating specifically comprises the following steps:

1) pretreatment of a titanium substrate: carrying out sand blasting, acid etching, cleaning and drying treatment on the surface of the titanium substrate;

2) preparation of the oxide interlayer by spray coating: controlling the temperature of the pretreated titanium substrate to be 180-300 ℃, and spraying a precursor solution onto the surface of the titanium substrate until the surface of the titanium substrate is completely covered by the precursor solution; then putting the mixture into a thermal oxidation furnace for heat preservation, and carrying out in-situ pyrolysis on the precursor solution;

3) repeating the step 2) for many times until the thickness of the oxide intermediate layer is 0.2-3 mu m, and finishing the preparation of the titanium substrate with the oxide intermediate layer;

4) preparing an iridium tantalum noble metal oxide active layer by using a brush coating method: coating a noble metal coating liquid on the surface of the titanium substrate with the oxide interlayer prepared in the step 3), and sintering; and repeating the brushing and sintering processes for multiple times to obtain the iridium tantalum noble metal oxide active layer, thereby completing the preparation of the coating titanium anode.

Further, the pretreatment in the step 1) comprises sand blasting, acid etching, cleaning and drying treatment;

the sand mold subjected to sand blasting treatment is selected from one or more of steel sand, brown corundum, quartz sand, white corundum and Hainan sand until the surface roughness Rz is more than 25;

the acid etching solution in the acid etching treatment is 5-10% of oxalic acid solution or/and 2-20% of hydrochloric acid solution.

Further, the precursor solution in the step 2) is selected from an organic solution containing one or more salts of iridium, tin, titanium, ruthenium, tantalum, antimony, niobium, platinum, rhodium and manganese, and the total metal ion concentration is 0.1-0.5 mol/L.

Further, the organic solvent adopted for preparing the organic solution is selected from one or more of n-butyl alcohol, isopropanol and butanediol.

Further, the spraying in the step 2) adopts a spray gun for atomization spraying, and the speed of the atomization spraying is 0.1-3 ml/min m²。

Further, the heat preservation temperature in the thermal oxidation furnace in the step 2) is not lower than 480 ℃.

Further, the heat preservation temperature in the thermal oxidation furnace in the step 2) is 500-540 ℃, and the heat preservation time is 15-120 min.

Further, the noble metal coating liquid in the step 4) is prepared from iridium compound and TaCl₅N-butyl alcohol solution and solvent; the iridium source in the iridium compound is selected from H₂IrCl₆、IrCl₃、K₂IrCl₆、H₂IrBr₆The solvent is one or more selected from ethylene glycol, n-butanol, isopropanol, propanol, ethanol and butanediol.

Further, the molar ratio of iridium to tantalum in the noble metal coating liquid is (0.3-1): (0-0.7), controlling the total metal ion concentration at 0.01-0.5 mol/L.

Further, the sintering temperature in the step 4) is 450-540 ℃, the thermal oxidation time is 10-30 min each time, and the final sintering time is 1-2 h.

Compared with the prior art, the technical scheme provided by the invention has the following beneficial effects: mixing a precursor metal salt of the middle layer with a specific solvent by an in-situ spraying method to obtain a precursor solution for preparing the bottom layer, spraying the precursor solution on a titanium substrate which is subjected to specific pretreatment and has the temperature of 180-300 ℃, carrying out in-situ thermal decomposition on the precursor solution to form a compact oxide deposition layer, and then carrying out high-temperature sintering to obtain a titanium substrate containing the oxide middle layer; then coating an iridium tantalum noble metal catalyst layer on the surface of the titanium substrate to obtain IrO₂-Ta₂O₅Coating titanium anodeAnd (4) a pole. The invention adopts the spraying technology and combines the step-by-step in-situ heat treatment method to prepare the oxide intermediate layer, and the noble metal catalyst layer is coated on the surface of the oxide intermediate layer, thereby effectively overcoming the technical defect that the service life of the electrode is short due to the uneven intermediate layer prepared by the traditional brush coating method and the roller coating method.

Detailed Description

The present invention is described in further detail below with reference to examples:

example 1:

the invention provides a preparation method of a titanium anode with a titanium-based coating, which comprises the following steps:

s1, pretreatment of the titanium substrate: cutting and sand blasting the titanium substrate to remove a surface oxide layer, then soaking in a 20% hydrochloric acid solution for 16h, finally etching in a slightly-boiling 10% oxalic acid solution for 2h, washing with deionized water after etching is finished, and drying for later use;

s2, preparing an oxide intermediate layer by adopting a spraying method, wherein the intermediate layer is a tin-manganese-tantalum oxide intermediate layer, and the preparation method comprises the following specific steps:

s2.1, adding a certain amount of SnCl₄、Mn(NO₃)₂And TaCl₅Dissolving the mixture in a mixed solution of n-butanol and concentrated hydrochloric acid, controlling the molar ratio Sn to Mn to be 5:1, the molar ratio Sn to Ta to be 8:1, and the total metal ion concentration to be 0.25mol/L, uniformly stirring, and preparing a precursor solution for later use;

s2.2, keeping the temperature of the titanium substrate subjected to surface pretreatment in the step S1 at 250 ℃, and atomizing and spraying the precursor solution in the step S2.1 onto the preheated titanium substrate by using a spray gun at the atomizing and spraying speed of 1.25mL/min m²Until the precursor solution completely covers the pretreated titanium substrate, transferring the titanium substrate into a thermal oxidation furnace at 530 ℃ and preserving the heat for 30 min;

s2.3, repeating the spraying and sintering in the step S2.2 for multiple times until the thickness of the prepared oxide intermediate layer reaches 1.5 mu m, and cooling to room temperature for later use;

s3, preparing a noble metal oxide active layer by adopting a brush coating method, wherein the metal oxide active layer is an iridium tantalum noble metal active layer, and the preparation steps are as follows:

S3.1measuring a certain amount of chloroiridic acid and tantalum pentachloride n-butyl alcohol solution, dissolving the chloroiridic acid and the tantalum pentachloride n-butyl alcohol solution in isopropanol, uniformly mixing, controlling the molar ratio of Ir to Ta to be 1:1 and the total concentration of metal ions to be 0.3mol/L, and dropwise adding a small amount of concentrated hydrochloric acid for preventing TaCl₅Hydrolyzing, and mechanically stirring for 4 hours at normal temperature; wherein, the concentrated hydrochloric acid accounts for 10 percent of the volume ratio of the iridium-tantalum mixed solution;

s3.2, uniformly stirring, uniformly brushing the prepared coating liquid on the titanium substrate containing the oxide intermediate layer, which is treated in the step S2, by using a brush, standing at room temperature for 20min, then putting the titanium substrate into an oven with the temperature of 100 ℃ for heat preservation for 10min, and transferring the titanium substrate into a muffle furnace for roasting at 500 ℃ for 20 min; repeatedly brushing for 10 times, and finally oxidizing and roasting at 520 ℃ for 1h to obtain IrO₂-Ta₂O₅Coating the titanium anode product.

Example 2:

the invention also provides a preparation method of the titanium-based coating titanium anode, which comprises the following steps:

s1, pretreatment of the titanium substrate: cutting a titanium substrate into 1380 x 260mm titanium plates, performing sand blasting treatment by using brown corundum until the roughness Rz is more than 25, removing surface oxide skin, performing ultrasonic treatment in an ethanol solution for 10min, finally etching in a slightly boiling 10% oxalic acid solution for 3.5h, washing with deionized water after etching is finished, and drying for later use;

s2, preparing an oxide intermediate layer by adopting a spraying method, wherein the intermediate layer is an iridium titanium platinum oxide intermediate layer, and the preparation steps are as follows:

s2.1, weighing a certain amount of chloroiridic acid and TaCl₅And H₂PtCl₆Dissolving in a mixed solution of isopropanol and concentrated hydrochloric acid, controlling the molar ratio Ir to Ta to be 1:9, controlling the molar ratio Pt to Ta to be 1:8, controlling the total metal ion concentration to be 0.3mol/L, uniformly stirring, and preparing into a precursor solution for later use;

s2.2, keeping the temperature of the titanium plate subjected to surface pretreatment in the step S1 at 300 ℃, and atomizing and spraying the precursor solution in the step S2.1 onto the surface of the preheated titanium plate by using a spray gun at the atomizing and spraying speed of 2mL/min m²Until the whole plate surface is completely covered by the precursor solution, transferring the plate surface into a thermal oxidation furnace at 520 ℃ and preserving the heat for 60 min;

s2.3, repeating the spraying and sintering in the step S2.2 for multiple times until the thickness of the prepared oxide intermediate layer reaches about 3 mu m, and cooling to room temperature for later use;

s3, preparing a metal oxide active layer by adopting a brush coating method, wherein the metal oxide active layer is an iridium tantalum noble metal oxide active layer, and the preparation method comprises the following specific steps:

s3.1, measuring a certain amount of chloroiridic acid and tantalum pentachloride n-butanol solution, dissolving the chloroiridic acid and tantalum pentachloride n-butanol solution in a mixed solution of isopropanol and n-butanol, controlling the molar ratio of Ir to Ta to be 3:2, controlling the total concentration of metal ions to be 0.32mol/L, and dropwise adding a small amount of concentrated hydrochloric acid to prevent TaCl₅Decomposing and mechanically stirring uniformly; wherein, the concentrated hydrochloric acid accounts for 30 percent of the volume ratio of the iridium-tantalum mixed solution;

s3.2, uniformly brushing the prepared coating liquid on the titanium plate containing the oxide intermediate layer after being treated in the step S2 by using a brush, naturally airing at room temperature, and then transferring to a muffle furnace at 510 ℃ for roasting for 10 min; repeatedly brushing for 15 times, and finally oxidizing and roasting at 520 ℃ for 1.5h to finally obtain IrO₂-Ta₂O₅Coating the titanium anode product.

Example 3:

the invention also provides a preparation method of the titanium-based coating titanium anode, which comprises the following steps:

s1, pretreatment of the titanium substrate: cutting a titanium substrate into a titanium plate with a certain specification, performing sand blasting treatment by using quartz sand until the roughness Rz is more than 25, removing a surface oxide skin, performing ultrasonic treatment in an ethanol solution for 10min, finally etching the titanium plate in a mixed solution formed by a 10% oxalic acid solution and a 2% hydrochloric acid solution for 2h, washing the titanium plate with deionized water after etching is completed, and drying the titanium plate for later use;

s2, preparing an oxide intermediate layer by adopting a spraying method, wherein the intermediate layer is an iridium titanium platinum oxide intermediate layer, and the preparation steps are as follows:

s2.1, weighing a certain amount of chloroiridic acid and TaCl₅And H₂PtCl₆Dissolving in mixed solution of isopropanol and concentrated hydrochloric acid, controlling the molar ratio Ir and Ta to be 1:9, the molar ratio Pt and Ta to be 1:8, and the total metal ion concentration to be 0.3mol/L, stirring uniformly, and preparing into precursorThe solution is ready for use;

s2.2, keeping the temperature of the titanium plate subjected to surface pretreatment in the step S1 at 180 ℃, and atomizing and spraying the precursor solution in the step S2.1 onto the surface of the preheated titanium plate by using a spray gun at the atomizing and spraying speed of 0.1mL/min m²Until the whole plate surface is completely covered by the precursor solution, transferring the plate surface into a thermal oxidation furnace at 500 ℃ and preserving the heat for 100 min;

s2.3, repeating the spraying and sintering in the step S2.2 for multiple times until the thickness of the prepared oxide intermediate layer reaches about 0.5 mu m, and cooling to room temperature for later use;

s3, preparing a metal oxide active layer by adopting a brush coating method, wherein the metal oxide active layer is an iridium tantalum noble metal oxide active layer, and the preparation method comprises the following specific steps:

s3.1, measuring a certain amount of solution of chloroiridic acid and tantalum pentachloride n-butanol into a mixed solution of isopropanol and n-butanol, controlling the molar ratio of Ir to Ta to be 3:2, controlling the total concentration of metal ions to be 0.5mol/L, and dropwise adding a small amount of concentrated hydrochloric acid for preventing chloroiridic acid and TaCl₅Decomposing and mechanically stirring uniformly; wherein, the concentrated hydrochloric acid accounts for 20 percent of the volume ratio of the iridium-tantalum mixed solution;

s3.2, uniformly brushing the prepared coating liquid on the titanium plate containing the oxide interlayer treated in the step S2 by using a brush, naturally airing at room temperature, and then transferring to a muffle furnace at 450 ℃ for roasting for 30 min; repeatedly brushing for 15 times, and finally oxidizing and roasting at 480 ℃ for 2h to finally obtain IrO₂-Ta₂O₅Coating the titanium anode product.

Experiments prove that the iridium tantalum oxide coating titanium anode prepared by the preparation method provided by the invention has uniform thickness of the middle layer, large binding force between the pure titanium substrate and the coating, good adhesion, capability of effectively preventing passivation of the titanium substrate and good electrochemical stability when used as an electrode.

The foregoing are merely exemplary embodiments of the present invention, which enable those skilled in the art to understand or practice the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention.

It is to be understood that the present invention is not limited to what has been described above, and that various modifications and changes may be made without departing from the scope thereof. The scope of the invention is limited only by the appended claims.