Electrodes capable of reversing polarity and their use

Abstract

This invention provides an electrode with reversible polarity and its use. [Solution] The electrode comprises a substrate containing a metal or an alloy thereof, an intermediate layer disposed on the substrate containing platinum group metals and platinum group metal oxides, and a catalytic layer disposed on the intermediate layer containing mixed metal oxides. The electrode may be used as an electrode for electrolysis, electrodialysis, or electroplating. The electrode can simultaneously meet the environmental requirements for the cathode and anode, improve environmental tolerance, protect the substrate, and perform polarity reversal to quickly and efficiently clean deposits on the electrode surface.

Description

[Technical Field]

[0001] This application is not limited to the field of electrochemistry, but in detail, it is not limited to the field of electrochemistry. However, this concerns electrodes with reversible polarity and their use. [Background technology]

[0002] Oxygen-generating titanium electrodes are used in precision processing such as electrochemical water treatment, metal element extraction, and electroplating. In the electrochemical industry, which focuses on processing, it is widely used as an environmentally friendly, insoluble anode. The oxygen-generating titanium electrode consists of a substrate made of pure metallic titanium or a titanium alloy, and on its surface. It is mainly composed of a formed noble metal oxide catalyst layer. The substrate provides conductivity and mechanical support. It becomes the main body. The catalyst layer significantly reduces the oxygen evolution potential in the aqueous solution through its oxidation-reduction process. This can lead to energy savings. At the same time, the anode consumes electrochemical energy. Because the rate is extremely low, the effective life is long. The oxygen evolution catalyst is mainly iridium oxide, and the base To protect the material from becoming passivated too quickly, titanium, tantalum, or niobium are used. The coating may be densified by mixing oxides of valve-type metals such as the above. Also, the catalyst layer and As an intermediate layer to protect the base material, a valve-shaped metal such as titanium or tantalum is used. Alloys or mixed oxides may also be used.

[0003] During the electrolysis process, the deposition of deposits on the electrode surface is unavoidable, affecting the electrolysis efficiency of the electrodes. This can affect the electrode surface and even cause electrode failure. Therefore, deposits on the electrode surface should be removed periodically. It is extremely important to clean it thoroughly.

[0004] The anode surface becomes acidic due to the oxygen evolution reaction, and the cathode surface becomes acidic due to the hydrogen evolution reaction. This creates an alkaline environment. Precipitates formed in an acidic environment are generally removed in an alkaline environment. Precipitates formed in an alkaline environment are generally easier to remove in an acidic environment. i. In a chlorine-generating electrode (where oxygen is partially generated), by reversing the polarity of the electrode, It is possible to remove deposits from the electrode surface. However, in the case of oxygen-generating electrodes, existing products After polarity reversal, an acceptable level of lifespan cannot be obtained. Anode failure during polarity reversal The investigation revealed that one reason for the short lifespan is the stability of the valve metal oxide within the coating. It was found that the main cause lies in the substrate, specifically the interface between the coating and the substrate. When electrode substrate materials (such as metallic titanium or titanium alloys) are used as the cathode, corrosion of the substrate may occur. The speed increases significantly, and at the same time, titanium hydride is generated, which coats the surface due to density-volume changes. It is thought that it will peel off.

[0005] The electrochemical response of Ti in aqueous solution is compared to that of true valve metals (Zr, Nb, Ta, etc.) and dynamics. It is located between active and passive metals (such as Fe, Co, Ni, and Cr). This has been documented in published literature. In particular, the formation of a Ti oxide film is similar to that of valve metals. While similar, the corrosion is analogous to the corrosion of dynamic and passive metals. Ti in an acidic electrolyte. The relationship between current and potential is shown in Non-Patent Document 1, and a schematic diagram is shown in Figure 1.

[0006] In the dynamic region, Ti is oxidized at a relatively rapid rate to form Ti(III) ions in solution. In the passivation region, Ti is covered with an oxide film, and oxidation becomes extremely slow. It is desirable to avoid a dynamic state and allow the anode to function in a passive state. A passivation can be formed in Ti, and alloying inhibits the anode half-reaction, or cathode It can function in two ways by promoting the half-reaction. By modifying the cathode, Ti is not Examples of alloying elements that have been suggested to be dynamic include Pt, Pd, Ni, and Mo. It can be achieved. In the research by Nakagawa et al. (Non-Patent Literature 2), alloying with Pt and Pd, As shown in Figures 2 and 3, it is clearly demonstrated that the dynamic region of Ti almost completely disappears.

[0007] The coating of precious metal oxides is relatively stable in both the anode and cathode. However, due to the thermal decomposition process, cracks, or more generally defects, are present. In typical oxygen generation applications, the low pH resulting from the anode reaction significantly accelerates the corrosion of the substrate. A common solution is to use an oxide-type interlayer, which significantly extends the effective lifespan. However, the inventors of this invention cannot solve the problem of the lifetime of polarity reversal with this type of interlayer. They discovered that. [Prior art documents] [Non-patent literature]

[0008] [Non-Patent Document 1] James J. Noel, The electrochemistry of Titanium corrosion, 1999, University of Manitoba, Doctor thesis [Non-Patent Document 2] Nakagawa etc., The effect of Pt and Pd alloying additions on the corrosion behavior of titanium in flfluoride-containing environments, Biomaterials 26 (2005) 2239-2246 [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] In light of the above understanding, in anodes used for polarity reversal applications, the problem that occurs in the substrate during cathode polarization A new coating to solve the problem and extend the lifespan in oxygen generation and polarity reversal applications A symmetrical structure is required.

[0010] Furthermore, applications that require the ability to reverse the polarity of electrodes, such as electrodialysis membrane stacks, are also relevant. There is also the need to periodically reverse the polarity of the electrodes in order to maintain the performance of the membrane stack. However, the use of chlorine generating electrodes and sodium chloride polar solutions involves relatively large amounts of chlorine. This leads to pollution problems. [Means for solving the problem]

[0011] A summary of the subject matter described in detail in this specification is provided below. This summary does not limit the scope of the claims. It is not intended to be a definitive statement.

[0012] To quickly and efficiently clean unwanted deposits from the electrode surface and to enable periodic polarity reversal of the electrode, In order to find a suitable oxygen-generating electrode with reversible polarity for use in the field in which this application The inventors, through years of meticulous research, improved the electrode structure, particularly the details shown in Figures 1-3. Based on this, by using an interlayer based on a Pt group metal that does not contain Ta, the cathode A hypothesis was put forward that the stability under dipole polarization and continuous polarity inversion could be improved.

[0013] This application provides an electrode capable of reversing polarity and including a substrate, an intermediate layer, and a catalytic layer. The substrate may include a metal or an alloy thereof; the intermediate layer is disposed on the substrate and may include a platinum group metal and a platinum group metal oxide; the catalytic layer is disposed on the intermediate layer and may include a mixed metal oxide.

[0014] In some embodiments, the intermediate layer may include a mixture of metallic platinum and iridium dioxide. The total content of platinum and iridium is 1 g / m 2 ~30 g / m 2 For example, 2 g / m 2 、3 g / m 2 、4 g / m 2 、5 g / m 2 、7.5 g / m 2 、8 g / m 2 、10 g / m 2 12 g / m 2 、15 g / m 2 、18 g / m 2 、22 g / m 2 、25 g / m 2 、28 g / m 2 and so on. The content of platinum (based on the metal content) may be 10 wt% - 90 wt% based on the total metal content of the intermediate layer, for example, 20 wt%, 30 wt%, 40 wt%, 50 wt%, 60 wt%, 70 wt%, 80 wt%, etc. The content of iridium may be 10 wt% - 90 wt% based on the total metal content of the intermediate layer, for example, 20 wt%, 30 wt%, 40 wt%, 50 wt%, 60 wt%, 70 wt%, 80 wt%, etc. Alternatively, the content of platinum (based on the metal content) is 40 based on the total metal content of the intermediate layer. Weight percentages range from 90% by weight, for example, 50%, 60%, 70%, 80%, etc. It may be present; the iridium content is 10% by weight to 60% based on the total metal content of the intermediate layer. It can also be expressed as a percentage by weight, for example, 20% by weight, 30% by weight, 40% by weight, 50% by weight, etc. .

[0015] In some embodiments, the intermediate layer is made of ruthenium, palladium, and rhodium. It may also contain one or more of the following metal oxides. The intermediate layer metal ruthenium, palladium, The rhodium content (based on metal content) is based on the total metal content of the intermediate layer. It may be less than 10% by weight, for example, 1% by weight, 2% by weight, 5% by weight, 8% by weight, etc.

[0016] In some embodiments, the platinum group metals in the intermediate layer diffuse into the substrate to form a mixed transition layer. Yes, that's fine. Diffusion can be achieved by heat treatment such as sintering.

[0017] In some embodiments, the catalytic layer may contain an iridium metal oxide, and tantalum and may also contain a mixed metal oxide of iridium, tantalum pentoxide and iridium dioxide. It may contain iridium. The iridium content of the catalytic layer is 3 g / m² based on the metal content. 2 ~100g / m 2 For example, 5g / m 2 , 8g / m 2 , 10g / m 2 15g / m 2 , 20 g / m 2 , 22g / m 2 25g / m 2 30g / m 2 35g / m 2 40g / m 2 , 50g / m 2 60g / m 270g / m 2 80g / m 2 90g / m 2 It is acceptable to do so. The iridium content (based on metal content) is 20 based on the total metal content of the catalytic layer. Weight % to 90% by weight, for example, 30% by weight, 40% by weight, 50% by weight, 60% by weight, 70% by weight It may be by weight %, 80% by weight, etc. The tantalum content (based on metal content) is, Based on the total metal content of the medium layer, the amount ranges from 10% to 80% by weight, for example, 20% by weight, 30% by weight. It may be %, 40% by weight, 50% by weight, 60% by weight, 70% by weight, etc.

[0018] In some embodiments, the catalytic layer is made of ruthenium, palladium, rhodium, titanium, Niobium, zirconium, hafnium, vanadium, molybdenum, and tungsten capsules It may further contain one or more metal oxides of any of the following: Ruthenium, Para in the catalytic layer. Dium, rhodium, titanium, niobium, zirconium, hafnium, vanadium, molybdenum The tungsten content (based on metal content) is, respectively, the total metal content of the catalytic layer. Based on this, it is less than 10% by weight, for example, 1%, 2%, 5%, 8%, etc. .

[0019] In some embodiments, the base material may be valve metal or an alloy of valve metal. The groups include titanium, tantalum, niobium, zirconium, hafnium, vanadium, and molybdenum. One or more of the following may be selected: , and tungsten. For example, the base material may be metallic titanium. Alternatively, it may be a titanium alloy.

[0020] Furthermore, this invention provides the use of an electrode whose polarity can be reversed, and this electrode is used for electrolysis, electrolysis It can be used as an electrode for analysis or electroplating.

[0021] In some embodiments, the electrode may be an oxygen-generating electrode. [Effects of the Invention]

[0022] This invention has the following beneficial effects compared to the prior art. (1) Platinum group metals and platinum group metal oxides so as to ensure a strong bond between the substrate and the intermediate layer. An intermediate layer containing [a specific component] is provided, improving the corrosion resistance of the substrate when used as a cathode. do. (2) The fabricated electrodes have higher resistance to organic solutions and can be used under a wider range of operating conditions. It can be used. (3) The electrodes must simultaneously meet the environmental requirements for the cathode and the anode. This enables improved environmental tolerance and protection of the substrate. (4) The prepared electrodes are then reversed in polarity to quickly and efficiently clean any deposits from the electrode surface. It can be purified. (5) The oxygen-generating electrode maintains excellent electrode life even when its polarity is periodically reversed. This makes it possible to perform this operation, and it can be used in fields where periodic reversal of electrode polarity is required.

[0023] Other features and advantages of this application are described in the following specification and are partially evident from the specification. This will become clearer, or will be understood by carrying out the present invention. The object of the present invention and Other advantages are realized by the structure specifically shown in the specification, claims and drawings. It is possible.

[0024] The drawings are for further understanding of the technical method of this application and constitute part of the specification. Used in conjunction with embodiments of the present application to illustrate the technical schemes of the present application. However, this is not intended to limit the technical methods of the present invention. [Brief explanation of the drawing]

[0025] [Figure 1] This is a schematic diagram showing the relationship between electric current and potential of Ti in an acidic electrolyte. [Figure 2] This is the anodic polarization curve of Ti and its alloys at pH 4.0 in artificial saliva containing 0.2% NaF. [Figure 3] This is the anodic polarization curve of a Ti-Pt alloy at pH 4.0 in artificial saliva containing 0.2% NaF. [Figure 4] This is a schematic diagram of an electrode structure relating to one example of the present invention. [Modes for carrying out the invention]

[0026] To further clarify the purpose, technical method, and advantages of this application, please refer to the attached drawings. The example of this application is described in detail below. Note that the example of this application and each component of the example are arbitrary and consistent. They can be combined.

[0027] An example of the present invention provides an electrode whose polarity can be reversed, and this electrode is as shown in Figure 4, for example. It comprises a base material 1, an intermediate layer 2, and a catalytic layer 3, which are stacked in order from bottom to top.

[0028] Alternatively, the intermediate layer 2 and the catalytic layer 3 may be arranged symmetrically on both sides of the substrate 1.

[0029] Base material 1 may be a valve-shaped metal or an alloy of valve-shaped metal. The valve-shaped metal may be titanium, tantalum, or nickel. Of the following: oats, zirconium, hafnium, vanadium, molybdenum, and tungsten It may be selected from 1. For example, base material 1 may be metallic titanium or a titanium alloy. .

[0030] Substrate 1 is pre-treated, for example, by sandblasting using conventional etching or pickling. It is acceptable.

[0031] The intermediate layer 2 may contain platinum group metals and platinum group metal oxides, including metallic platinum and oxides. The mixture may be iridium, and the intermediate layer 2 may be ruthenium, palladium, and rhodium. It may contain one or more of the following metal oxides. Total content of platinum and iridium Based on the metal content, 1 g / m 2 ~30g / m 2 This is acceptable. Total metal content of the intermediate layer Based on this, the platinum content (based on the metal content) may be 10% to 90% by weight. The iridium content (based on metal content) may be 10% to 90% by weight; The content of metallic ruthenium, palladium, and rhodium (based on their metallic content) is as follows: or less than 10% by weight based on the total metal content of the intermediate layer. Based on the quantity, even if the platinum content (based on the metal content) is 40% to 90% by weight Often, even if the iridium content (based on metal content) is between 10% and 60% by weight Often; the content (based on the metal content) of the metals ruthenium, palladium, and rhodium is Each is less than 10% by weight, based on the total metal content of the intermediate layer.

[0032] The platinum group metal used in intermediate layer 2 has a higher oxygen evolution potential than the material used in catalytic layer 3. Because the value is high, the electrode substrate is not passedivated under oxygen-evolving conditions. At the same time, the metal Due to the presence of platinum, intermediate layer 2 exhibits stable performance under hydrogen generation conditions, and the cathode's operating ring It has high resistance to the boundary. Therefore, when the intermediate layer 2 is used as the cathode and anode... This allows for the protection of the substrate at the same time, and as a result, the electrode can be used when polarity is reversed, Surface deposits can be cleaned quickly and efficiently, and periodic reversal of electrode polarity is not required. It can be used in various fields.

[0033] Intermediate layer 2 is formed by coating a precursor solution containing the corresponding element, drying it, and then sintering it. It is formed from the platinum precursor, which exists in a metallic state during the subsequent sintering process. Platinum readily diffuses into substrate 1 (e.g., titanium). However, the coating of pure metallic platinum The medium is unstable in a highly acidic environment. The stability of the interlayer is achieved by adding a predetermined amount of iridium (which is converted to iridium dioxide during sintering). It can be improved by doing so.

[0034] The precursor for forming the intermediate layer 2 is prepared as a coating solution, for example, in an aqueous hydrochloric acid solution It can be formulated with chloroplatinic acid and chloridium acid, and the platinum content is 2.0 by weight. %~6.0% by weight, for example, 3.0% by weight, 4.0% by weight, 4.2% by weight, 4.8% by weight It may be 5.0% by weight, etc. Apply to the pre-treated substrate 1 with a brush, apply with a roller, A predetermined amount of coating liquid is applied by conventional coating methods such as spraying. The prepared substrate 1 is dried in air or in an oven at 60°C to 90°C, for example, 80°C, and then... Then, in an air-circulating electric furnace at 400°C to 600°C for 10 to 30 minutes, for example, 20 minutes at 500°C. Intermediate sintering is performed. Coating and sintering can be done multiple times, and after each coating, firing is performed. One sintering process is performed. During the sintering process, chloroplatinic acid is decomposed into metallic platinum and a small amount of platinum oxide. iridium chloride decomposes into iridium dioxide. A mixture of platinum and iridium dioxide. The material can also be directly coated onto substrate 1 using other chemical vapor deposition or physical vapor deposition methods. .

[0035] The catalytic layer 3 may contain iridium metal oxide, and may be a mixture of tantalum and iridium. It may also contain alloying metal oxides; for example, catalytic layer 3 may contain tantalum pentoxide and iridium dioxide. It may contain zinc. Also, the catalytic layer 3 may contain ruthenium, palladium, rhodium, and titanium. niobium, zirconium, hafnium, vanadium, molybdenum, and tungsten It may contain one or more of the following metal oxides. The iridium content of the catalytic layer is: Based on metal content, 3g / m 2 ~100g / m 2 This may be the case. Total metal content of the catalytic layer Based on this, the iridium content (based on metal content) was 20% to 90% by weight. The tantalum content (based on metal content) may be between 10% and 80% by weight. Metals: ruthenium, palladium, rhodium, titanium, niobium, zirconium, hafnium The vanadium, molybdenum, and tungsten content, respectively, is the total metal content of the intermediate layer. Based on weight, it is less than 10% by weight.

[0036] The method for forming the catalytic layer 3 is the same as the method for forming the intermediate layer 2, for example, iridium chloride Tantalum pentachloride may be used as a precursor, and the coating solution may be prepared with a hydrochloric acid solution.

[0037] Furthermore, the intermediate layer 2 or catalytic layer 3 may contain other elements, corresponding to the coating liquid. It can be prepared by adding elemental precursors, and generally by adding chlorides of other elements. stomach.

[0038] After forming the intermediate layer 2 on the substrate 1, some of the metal elements in the intermediate layer 2 can diffuse into the substrate 1. The base material 1 and the intermediate layer 2 may be heat-treated. This strengthens the bond between the base material 1 and the intermediate layer 2, and the casing The corrosion resistance of base material 1 when used as a base is also improved. During heat treatment, base material 1 and intermediate layer 2 Sinter in an air-circulating electric furnace at 500°C to 600°C for 3 to 6 hours, for example, 4 hours at 530°C. You may do so. [Examples]

[0039] Example 1 Using Gr1 grade industrial pure titanium as the base material, after heat treatment at 500°C for 1 hour, Etched in 30.0 wt% sulfuric acid at 90°C for 4 hours, then washed in ultrapure water using an ultrasonic device. Then, it was dried in the air.

[0040] The intermediate layer coating solution was prepared as a hydrochloric acid solution containing iridium chloride and platinum chloride. Based on the content, the mass ratio of platinum to iridium is 8:2, and the platinum content is 4.8 times. The amount was in percent, and the concentration of HCl was 10.0% by weight (added as saturated hydrochloric acid). (Thermal decomposition method) Then, the titanium metal substrate is coated four times with an intermediate coating solution (with platinum and iridium in each coating). The total amount of zinc is 1.0 g / m³ based on the metal content. 2 (It was), after each coating The material was thermally decomposed at 500°C for 20 minutes to obtain an intermediate layer containing metallic platinum and iridium dioxide. The total amount of platinum and iridium in the intermediate layer is 4.0 g / m², based on the metal content. 2 was . The base material and the intermediate layer were sintered at 530°C for 4 hours.

[0041] The coating solution for the catalytic layer is prepared as a hydrochloric acid solution containing iridium chloride and tantalum pentachloride. Based on the metal content, the iridium:tantalum mass ratio is 7:3, and iridium The content was 6.0% by weight, and the hydrochloric acid concentration was 10.0% by weight. The intermediate layer was obtained by thermal decomposition. The catalyst layer coating solution was applied 10 times (the amount of iridium in each coating was different from that of the metal). Based on content, 1.0g / m 2 (This was the case.) After each coating, heat was applied at 450°C for 20 minutes. The solution was then used to obtain a catalytic layer containing a mixed metal oxide of tantalum pentoxide and iridium dioxide. The total amount of iridium in the catalytic layer was 10.0 g / m³ based on the metal content. 2 was .

[0042] Comparative Example 1 Using Gr1 grade industrial pure titanium as the base material, after heat treatment at 500°C for 1 hour, Etched in 30.0 wt% sulfuric acid at 90°C for 4 hours, then washed in ultrapure water using an ultrasonic device. Then, it was dried in the air.

[0043] The intermediate coating solution was prepared as a hydrochloric acid solution containing tantalum chloride. The tantalum content was: Based on the metal content, it was 6.0% by weight, and the hydrochloric acid concentration was 10.0% by weight. Thermal decomposition The method involves coating a titanium metal substrate with an intermediate coating solution three times (with tantalum in each coating). The total amount is 1.0g / m based on the metal content. 2 (This was the case), and after each coating, 520°C The mixture was subjected to thermal decomposition for 20 minutes to obtain an intermediate layer containing tantalum pentoxide. The amount is 3.0 g / m² based on the metal content. 2 That was the case.

[0044] The coating solution for the catalytic layer is prepared as a hydrochloric acid solution containing iridium chloride and tantalum pentachloride. Based on the metal content, the iridium:tantalum mass ratio is 7:3, and iridium The content was 6.0% by weight, and the hydrochloric acid concentration was 10.0% by weight. The intermediate layer was obtained by thermal decomposition. The catalyst layer coating solution was applied 14 times (the amount of iridium in each coating was different from that of the metal). Based on content, 1.0g / m 2 (This was the case.) After each coating, heat was applied at 450°C for 20 minutes. The solution was then used to obtain a catalytic layer containing a mixed metal oxide of tantalum pentoxide and iridium dioxide. The total amount of iridium in the catalytic layer was 14.0 g / m² based on the metal content. 2 was .

[0045] Performance testing The positive and negative polarity and current output of the rectifier are controlled by software, and the lifespan of the electrodes is controlled. The test was conducted under the following conditions.

[0046] Test 1 The test conditions were 5000 A / m 2 , 15% sulfuric acid electrolyte, the time interval for polarity reversal was 5 minutes. (That is, the polarity of the rectifier was reversed every 5 minutes during the test.) The accelerated lifetime of the electrode in Example 1 was 6.1 mAh / m². 2 That was the case. The accelerated lifetime of the electrode in Comparative Example 1 was 0.3 mAh / m². 2 That was the case.

[0047] Test 2 The test conditions were 45,000 A / m. 2 The temperature was 80°C, 25% sulfuric acid electrolyte, and there was no polarity reversal. . The accelerated lifetime of the electrode in Example 1 was 40.0 mAh / m². 2 That was the case. The accelerated life of the electrode in Comparative Example 1 was 35.0 mAh / m². 2 That was the case.

[0048] Accelerated life refers to operating under harsher conditions than actual use (workpiece), such as higher current, higher temperature, and stronger acidity. This refers to a method of evaluating electrode performance by simulating the electrode reaching the end of its lifespan under specific environmental conditions.

[0049] Because most of the deposits on the electrode are removed during the electrode polarity reversal process, the self of the oxygen-evolving electrode This enables cleaning and extends the effective lifespan of the electrodes.

[0050] Based on the results of Test 1 and Test 2 of Comparative Example 1 described above, for applications that periodically reverse polarity... In this case, the accelerated life of electrodes using tantalum pentoxide as an intermediate layer is extremely short, therefore, electrode properties It is clear that the function cannot meet the usage requirements.

[0051] The electrode of Example 1 uses metallic platinum and iridium dioxide as the intermediate layer, and the intermediate layer When compared to the electrode of Comparative Example 1, which uses a general tantalum pentoxide, under DC conditions (electrode inversion), In tests where this is not performed, under test 2), the effective life of the electrode in Example 1 is the same as the effective life of the electrode in Comparative Example 1. Compared to the lifespan, there was a slight improvement. However, in the case of polarity reversal (Test 1), the electrode of Example 1 The effective life is significantly extended compared to the effective life of the electrode in Comparative Example 1.

[0052] Example 2 Using Gr1 grade industrial pure titanium as the base material, after heat treatment at 500°C for 1 hour, Etched in 30.0 wt% sulfuric acid at 90°C for 4 hours, then washed in ultrapure water using an ultrasonic device. Then, it was dried in the air.

[0053] The intermediate coating solution is an n-butanol solution containing iridium chloride and platinum chloride. It was prepared using the following method. Based on the metal content, the mass ratio of platinum to iridium is 7:3, and the platinum content The amount is 4.2% by weight, and the concentration of HCl is 2.0% by weight (added as saturated hydrochloric acid). The remaining component was n-butanol. The intermediate coating liquid was applied to the titanium metal substrate by thermal decomposition. The coating is applied multiple times (the total amount of platinum and iridium in each coating is based on the metal content). 1.25 g / m 2 (This was the case), and after each coating, thermal decomposition was performed at 500°C for 20 minutes. An intermediate layer containing metallic platinum and iridium dioxide was obtained. The weighing is based on the metal content, at 10.0 g / m². 2 That was the case. The base material and the intermediate layer were sintered at 540°C for 6 hours.

[0054] The coating solution for the catalyst layer contains n-butanol, which is composed of iridium chloride and tantalum ethoxide. It was prepared as a solution. Based on the metal content, the iridium:tantalum mass ratio was 7:3. The iridium content is 5.0% by weight, and the concentration of HCl is 2.0% by weight (saturated hydrochloric acid). (Added as) and the remaining component was n-butanol. A catalyst layer was formed in the intermediate layer by thermal decomposition. The coating solution was applied in 8 coats (the amount of iridium in each coating was based on the metal content). 1.0g / m 2 (This was the case.) After each coating, thermal decomposition was performed at 450°C for 20 minutes. A catalytic layer containing a mixed metal oxide of tantalum pentoxide and iridium dioxide was obtained. The total amount of iridium in the layer is 8.0 g / m², based on the metal content. 2 That was the case.

[0055] Comparative Example 2 Using Gr1 grade industrial pure titanium as the base material, after heat treatment at 500°C for 1 hour, Etched in 30.0 wt% sulfuric acid at 90°C for 4 hours, then washed in ultrapure water using an ultrasonic device. Then, it was dried in the air.

[0056] The intermediate coating solution was prepared as an n-butanol solution containing tantalum ethoxide. The tantalum content was 6.0% by weight based on the metal content. Titanium metal was obtained by thermal decomposition. The substrate is coated with an intermediate coating solution three times (the total amount of tantalum in each coating is metal Based on content, 1.0g / m 2 (This was the case), and after each coating, heat was applied at 500°C for 20 minutes. The solution was performed to obtain an intermediate layer containing tantalum pentoxide. The tantalum content in the intermediate layer was determined to be the same as that of the metal. Based on available quantities, 3.0 g / m 2 That was the case.

[0057] The coating solution for the catalyst layer contains n-butanol, which is composed of iridium chloride and tantalum ethoxide. It was prepared as a solution. Based on the metal content, the iridium:tantalum mass ratio was 7:3. The iridium content was 6.0% by weight. A catalyst coating solution was applied to the intermediate layer by thermal decomposition. It was coated 8 times (the amount of iridium in each coating was 1 based on the metal content). 0g / m 2 (This was the case.) After each coating, thermal decomposition was performed at 480°C for 20 minutes, and pentoxide was produced. A catalytic layer containing a mixed metal oxide of iontal and iridium dioxide was obtained. The total amount of rhizium is 18.0 g / m³ based on the metal content. 2 That was the case.

[0058] Performance testing The positive and negative polarity and current output of the rectifier are controlled by software, and the lifespan of the electrodes is controlled. The test was conducted under the following conditions.

[0059] Test 1 The test conditions were 5000 A / m 2 , 15% sulfuric acid electrolyte, the time interval for polarity reversal was 5 minutes. Ta. The accelerated lifetime of the electrode in Example 2 was 10.8 mAh / m².2 That was the case. The accelerated lifetime of the electrode in Comparative Example 2 was 0.2 mAh / m². 2 That was the case.

[0060] Test 2 The test conditions were 45,000 A / m. 2 The temperature was 80°C, the electrolyte was 25% sulfuric acid, and there was no polarity reversal. The accelerated lifetime of the electrode in Example 2 is 68 mAh / m². 2 That was the case. The accelerated lifetime of the electrode in Comparative Example 2 was 52.0 mAh / m². 2 That was the case.

[0061] Similarly, since most of the deposits on the electrodes are removed during the electrode polarity reversal process, oxygen generation is possible. Self-cleaning of the electrode is achieved. Furthermore, Example 2 has a longer effective life under DC conditions compared to Comparative Example 2. Life expectancy improves, but under polarity reversal conditions, lifespan is significantly extended.

[0062] Example 3 Using Gr1 grade industrial pure titanium as the base material, after heat treatment at 500°C for 1 hour, Etched in 7.5 wt% oxalic acid at 90°C for 1 hour, then cooled to 80°C and further etched for 12 hours. The material was etched, washed in ultrapure water using an ultrasonic device, and dried in air.

[0063] The intermediate coating solution is an n-butanol solution containing iridium chloride and platinum chloride. It was prepared using the following method. Based on the metal content, the mass ratio of platinum to iridium is 5:5, and the platinum content The amount is 3.0% by weight, and the concentration of hydrochloric acid is 2.0% by weight (added as saturated hydrochloric acid). The remaining component was n-butanol. The intermediate coating solution was applied twice to the titanium metal substrate using a thermal decomposition method. The coating is applied (the total amount of platinum and iridium in each coating is based on the metal content). 1.0 g / m 2(Then), after each coating, thermal decomposition was performed at 500°C for 20 minutes, and the metal An intermediate layer containing platinum and iridium dioxide was obtained. The total amount of platinum and iridium in the intermediate layer. This is based on the metal content of 2.0 g / m². 2 That was the case. The base material and the intermediate layer were sintered at 520°C for 3 hours.

[0064] The coating solution for the catalyst layer contains n-butanol, which is composed of iridium chloride and tantalum ethoxide. It was prepared as a solution. Based on the metal content, the iridium:tantalum mass ratio was 7:3. The iridium content was 5.0% by weight. The catalyst coating solution was applied to the intermediate layer by thermal decomposition. The coating was applied multiple times (the amount of iridium in each coating was 1.0 based on the metal content). g / m 2 (This was the case.) After each coating, thermal decomposition was performed at 450°C for 20 minutes, and tang oxide was produced. A catalytic layer containing a mixed metal oxide of tal and iridium dioxide was obtained. The total amount of zinc is 8.0 g / m³ based on the metal content. 2 That was the case.

[0065] Comparative Example 3 Using Gr1 grade industrial pure titanium as the base material, after heat treatment at 500°C for 1 hour, Etched in 7.5 wt% oxalic acid at 90°C for 1 hour, then cooled to 80°C and further etched for 12 hours. The material was etched, washed in ultrapure water using an ultrasonic device, and dried in air.

[0066] The intermediate coating liquid contains n-butano ethoxide and tetrabutyl titanate. It was prepared as a tantalum solution. Based on the metal content, the mass ratio of tantalum to titanium was 7:3. The tantalum content was 6.0% by weight. The intermediate layer coating was applied to the titanium metal substrate by thermal decomposition. The solution is coated four times (the amount of mixed titanium oxide-tantalum in each coating is the mixed acid Based on the compound, 0.75 g / m 2 (This was the case), and after each coating, heat was applied at 520°C for 20 minutes. The solution was performed to obtain an intermediate layer containing mixed titanium oxide-tantalum. The tantalum content is 3.0 g / m², based on the content of mixed oxides. 2 That was the case.

[0067] The coating solution for the catalyst layer contains n-butanol, which is composed of iridium chloride and tantalum ethoxide. It was prepared as a solution. Based on the metal content, the iridium:tantalum mass ratio was 7:3. The iridium content was 6.0% by weight. A catalyst coating solution was applied to the intermediate layer by thermal decomposition. 0 coatings (The amount of iridium in each coating is 1 based on the metal content.) 0g / m 2 (This was the case.) After each coating, thermal decomposition was performed at 500°C for 20 minutes, and pentoxide was produced. A catalytic layer containing a mixed metal oxide of iontal and iridium dioxide was obtained. The total amount of rhizium is 10.0 g / m³ based on the metal content. 2 That was the case.

[0068] Performance testing The positive and negative polarity and current output of the rectifier are controlled by software, and the lifespan of the electrodes is controlled. The test was conducted under the following conditions.

[0069] Test 1 The test conditions were 5000 A / m 2 , 15% sulfuric acid electrolyte, the time interval for polarity reversal was 5 minutes. Ta. The accelerated lifetime of the electrode in Example 3 is 2.8 mAh / m². 2 That was the case. The accelerated life of the electrode in Comparative Example 3 was 0.3 mAh / m². 2 That was the case.

[0070] Test 2 The test conditions were 45,000 A / m. 2 The temperature was 80°C, 25% sulfuric acid electrolyte, and there was no polarity reversal. . The accelerated lifetime of the electrode in Example 3 was 27.0 mAh / m². 2 That was the case. The accelerated lifetime of the electrode in Comparative Example 3 was 24.8 mAh / m². 2 That was the case.

[0071] Similarly, since most of the deposits on the electrodes are removed during the electrode polarity reversal process, oxygen generation is possible. Self-cleaning of the electrode is achieved. Furthermore, Example 3 has a longer effective life under DC conditions compared to Comparative Example 3. Life expectancy improves, but under polarity reversal conditions, lifespan is significantly extended.

[0072] Example 4 Using Gr1 grade industrial pure titanium as the base material, after heat treatment at 500°C for 1 hour, Etched in 7.5 wt% oxalic acid at 90°C for 1 hour, then cooled to 80°C and further etched for 12 hours. The material was etched, washed in ultrapure water using an ultrasonic device, and dried in air.

[0073] The intermediate coating solution is an n-butanol solution containing iridium chloride and platinum chloride. It was prepared using the following method. Based on the metal content, the mass ratio of platinum to iridium is 6:4, and the platinum content The amount is 4.0% by weight, and the concentration of HCl is 2.0% by weight (added as saturated hydrochloric acid). The remaining component was n-butanol. The intermediate coating liquid was applied to the titanium metal substrate by thermal decomposition. The coating is applied multiple times (the total amount of platinum and iridium in each coating is based on the metal content). 1.25 g / m 2 (This was the case), and after each coating, thermal decomposition was performed at 500°C for 20 minutes. An intermediate layer containing metallic platinum and iridium dioxide was obtained. The weighing is based on the metal content, at 5.0 g / m². 2 That was the case. The base material and the intermediate layer were sintered at 520°C for 4 hours.

[0074] The coating solution for the catalyst layer contains n-butanol, which is composed of iridium chloride and tantalum ethoxide. It was prepared as a solution. Based on the metal content, the iridium:tantalum mass ratio was 8:2. The iridium content was 4.5% by weight. A catalyst coating solution was applied to the intermediate layer by thermal decomposition. 0 coatings (The amount of iridium in each coating is 1 based on the metal content.) 0g / m 2 (This was the case.) After each coating, thermal decomposition was performed at 450°C for 20 minutes, and pentoxide was produced. A catalytic layer containing a mixed metal oxide of iontal and iridium dioxide was obtained. The total amount of rhizium is 10.0 g / m³ based on the metal content. 2 That was the case.

[0075] Comparative Example 4 Using Gr1 grade industrial pure titanium as the base material, after heat treatment at 500°C for 1 hour, Etched in 7.5 wt% oxalic acid at 90°C for 1 hour, then cooled to 80°C and further etched for 12 hours. The material was etched, washed in ultrapure water using an ultrasonic device, and dried in air.

[0076] The intermediate coating liquid contains n-butano ethoxide and tetrabutyl titanate. It was prepared as a tantalum solution. Based on the metal content, the mass ratio of tantalum to titanium was 9:1. The tantalum content was 6.0% by weight. The intermediate layer coating was applied to the titanium metal substrate by thermal decomposition. The solution is coated four times (the amount of mixed titanium oxide-tantalum in each coating is the mixed acid Based on the compound, 0.75 g / m 2 (This was the case), and after each coating, heat was applied at 500°C for 20 minutes. The solution was carried out to obtain an intermediate layer containing mixed titanium oxide - tantalum. The content of mixed titanium oxide - tantalum in the intermediate layer was 3.0 g / m based on the content of the mixed oxide. 2 It was.

[0077] The coating liquid for the catalyst layer was prepared as an n - butanol solution containing iridium chloride acid and tantalum ethoxide. Based on the metal content, the mass ratio of iridium:tantalum was 8:2, and the content of iridium was 4.5 wt%. The coating liquid for the catalyst layer was coated on the intermediate layer 1 to 3 times by the thermal decomposition method (the amount of iridium in each coating was 1. 0 g / m 2 based on the metal content). After each coating, thermal decomposition was carried out at 500 °C for 20 minutes to obtain a catalytic layer containing a mixed metal oxide of tantalum pentoxide and iridium dioxide. The total amount of iridium in the catalytic layer was 13.0 g / m based on the metal content. It was. 2 It was.

[0078] Performance test The positive polarity, negative polarity, and current output of the rectifier were controlled by software, and the electrode life test was carried out under the following conditions.

[0079] Test 1 The test conditions were 5000 A / m 2 , 15% sulfuric acid electrolyte, and the time interval for polarity reversal was 5 minutes. It was. The accelerated life of the electrode in Example 4 was 5.8 Mah / m 2 It was. The accelerated life of the electrode in Comparative Example 4 was 0.3 Mah / m 2 It was.

[0080] Test 2 The test conditions were 45000 A / m 2 , 80 °C, 25% sulfuric acid electrolyte, and no polarity reversal. It was. The accelerated lifetime of the electrode in Example 4 was 32.0 mAh / m². 2 That was the case. The accelerated lifetime of the electrode in Comparative Example 4 was 37.8 mAh / m². 2 That was the case.

[0081] Similarly, since most of the deposits on the electrodes are removed during the electrode polarity reversal process, oxygen generation is possible. Self-cleaning of the electrode is achieved. Furthermore, Example 4 has a longer effective life under DC conditions compared to Comparative Example 4. While their lifespans are equal, under polarity reversal conditions, their lifespan is significantly extended.

[0082] Example 5 Using Gr1 grade industrial pure titanium as the base material, after heat treatment at 500°C for 1 hour, Etched in 7.5 wt% oxalic acid at 90°C for 1 hour, then cooled to 80°C and further etched for 12 hours. The material was etched, washed in ultrapure water using an ultrasonic device, and dried in air.

[0083] The intermediate coating solution contains iridium chloride, platinum chloride, and ruthenium trichloride. - Prepared as a butanol solution. Based on metal content, the composition was platinum:iridium:ruthenium. The mass ratio is 60:35:5, the platinum content is 4.0% by weight, and the HCl concentration is It was 2.0% by weight (added as saturated hydrochloric acid), and the remaining component was n-butanol. The titanium metal substrate was coated six times with an intermediate coating solution using a decomposition method (platinum in each coating). The total amount of iridium is 1.25 g / m³ based on the metal content. 2 (was), each coat After fermentation, thermal decomposition is carried out at 500°C for 20 minutes to obtain metallic platinum, ruthenium dioxide, and dioxide. An intermediate layer containing iridium oxide was obtained. The total amount of platinum and iridium in the intermediate layer was the metal content. Based on quantity, 7.5g / m 2 That was the case. The base material and the intermediate layer were sintered at 520 °C for 4 hours.

[0084] The coating liquid for the catalyst layer was prepared as an n-butanol solution containing iridium chloride acid and tantalum ethoxide. Based on the metal content, the mass ratio of iridium to tantalum was 8:2, and the content of iridium was 4.5 wt%. The coating liquid for the catalyst layer was coated on the intermediate layer twice by the thermal decomposition method (the amount of iridium in each coating was 1.0 g / m based on the metal content). After each coating, thermal decomposition was carried out at 450 °C for 20 minutes to obtain a catalytic layer containing a mixed metal oxide of tantalum pentoxide and iridium dioxide. The total amount of iridium in the catalytic layer was 22.0 g / m based on the metal content. 2 After thermal decomposition at 450 °C for 20 minutes after each coating, a catalytic layer containing a mixed metal oxide of tantalum pentoxide and iridium dioxide was obtained. The total amount of iridium in the catalytic layer was 22.0 g / m based on the metal content. 2

[0085] Comparative Example 5 Industrial pure titanium of Gr1 grade was used as the base material, heat-treated at 500 °C for 1 hour, then etched in 7.5 wt% oxalic acid at 90 °C for 1 hour, cooled to 80 °C and etched for another 12 hours, washed in ultrapure water with an ultrasonic device, and dried in air. The coating liquid for the intermediate layer was prepared as an n-butanol solution containing tantalum ethoxide and tetrabutyl titanate. Based on the metal content, the mass ratio of tantalum to titanium was 9:1, and the content of tantalum was 6.0 wt%. The coating liquid for the intermediate layer was coated on the metal titanium base material 4 times by the thermal decomposition method (the amount of mixed titanium oxide - tantalum in each coating was 0.75 g / m based on the mixed oxide).

[0086] After each coating, thermal decomposition was carried out at 500 °C for 20 minutes to obtain an intermediate layer containing mixed titanium oxide - tantalum. Based on the metal content, the mass ratio of tantalum to titanium was 9:1, and the content of tantalum was 6.0 wt%. The coating liquid for the intermediate layer was coated on the metal titanium base material 4 times by the thermal decomposition method (the amount of mixed titanium oxide - tantalum in each coating was 0.75 g / m based on the mixed oxide). After each coating, thermal decomposition was carried out at 500 °C for 20 minutes to obtain an intermediate layer containing mixed titanium oxide - tantalum. 2 After each coating, thermal decomposition was carried out at 500 °C for 20 minutes to obtain an intermediate layer containing mixed titanium oxide - tantalum. The mixed titanium oxide - tantalum in the intermediate layer ​​​​​The tantalum content is 3.0 g / m², based on the content of mixed oxides. 2 That was the case.

[0087] The coating solution for the catalyst layer contains n-butanol, which is composed of iridium chloride and tantalum ethoxide. It was prepared as a solution. Based on the metal content, the iridium:tantalum mass ratio was 8:2. The iridium content was 4.5% by weight. The catalyst coating liquid was applied to the intermediate layer by thermal decomposition. It was coated 9 times (the amount of iridium in each coating was 1 based on the metal content). 0g / m 2 (This was the case.) After each coating, thermal decomposition was performed at 500°C for 20 minutes, and pentoxide was produced. A catalytic layer containing a mixed metal oxide of iontal and iridium dioxide was obtained. The total amount of rhizium is 29.0 g / m³ based on the metal content. 2 That was the case.

[0088] Performance testing The positive and negative polarity and current output of the rectifier are controlled by software, and the lifespan of the electrodes is tested. The experiment was conducted under the following conditions.

[0089] Test 1 The test conditions were 5000 A / m 2 , 15% sulfuric acid electrolyte, the time interval for polarity reversal was 5 minutes. Ta. The accelerated lifetime of the electrode in Example 5 was 9.74 MHz / m². 2 That was the case. The accelerated lifetime of the electrode in Comparative Example 5 was 0.3 mAh / m². 2 That was the case.

[0090] Test 2 The test conditions were 45,000 A / m. 2 The temperature was 80°C, 25% sulfuric acid electrolyte, and there was no polarity reversal. . The accelerated lifetime of the electrode in Example 5 was 74.0 mAh / m². 2 That was the case. The accelerated lifetime of the electrode in Comparative Example 5 was 57.8 mAh / m². 2 That was the case.

[0091] Similarly, since most of the deposits on the electrodes are removed during the electrode polarity reversal process, oxygen generation is possible. Self-cleaning of the electrode is achieved. Furthermore, Example 5 has a longer effective life under DC conditions compared to Comparative Example 5. Life expectancy improves, but under polarity reversal conditions, lifespan is significantly extended.

[0092] The embodiments disclosed in this application are as described above, but the above content makes it easy to understand this application. This is merely an embodiment used in a way that allows for interpretation, and is not intended to limit the present application. Those skilled in the art will, without departing from the spirit and scope of this application, describe the embodiments and details of the present invention. Any modifications and changes may be made, but the scope of patent protection of this application is limited to the attached claims. It shall comply with the scope defined therein. [Explanation of Symbols]

[0093] a: Hydrogen generation region b:Dynamic region c: Transition from dynamic to passive d: Passive region 1: Base material 2: Middle class 3: Catalytic layer

Claims

1. An electrode whose polarity can be reversed, A substrate containing a metal or an alloy thereof; Displaced on the substrate, an intermediate layer comprising platinum group metals and platinum group metal oxides; An electrode comprising: a catalytic layer disposed on the intermediate layer and containing a mixed metal oxide;

2. The electrode according to claim 1, wherein the intermediate layer comprises a mixture of metallic platinum and iridium dioxide. 。

3. The total content of platinum and iridium in the aforementioned intermediate layer is 1% by weight, based on the aforementioned metal content. It is 30% by weight; preferably, the platinum content of the intermediate layer is equal to the total metal content of the intermediate layer. The iridium content in the intermediate layer is preferably 10% to 90% by weight, based on the amount. The amount is 10% to 90% by weight based on the total metal content of the intermediate layer; preferably, Based on the total metal content of the intermediate layer, the platinum content of the intermediate layer is 40% to 90% by weight. Claim 2, wherein the iridium content of the intermediate layer is 10% by weight to 60% by weight. The electrodes described above.

4. The aforementioned intermediate layer further contains one or more of ruthenium, palladium, and rhodium. It contains; preferably, the intermediate layer contains metallic ruthenium, palladium, and rhodium. Claim 2, where each of the amounts is less than 10% by weight based on the total metal content of the intermediate layer. Or the electrode according to claim 3.

5. Claim 1, wherein the platinum group metal in the intermediate layer diffuses into the substrate to form a mixed transition layer. The electrode described in any one of items ~4.

6. The catalytic layer comprises an iridium metal oxide; preferably, the catalytic layer comprises tantalum and iridium, comprising a mixed metal oxide; preferably, the catalytic layer is tantalum pentoxide. and iridium dioxide; preferably, the iridium content of the catalytic layer is gold Based on the amount of each component, 3 g / m ２ ~100g / m ２ And; preferably, the catalytic layer The zinc content is 20% to 90% by weight, based on the total metal content of the catalytic layer. Preferably, the tantalum content of the catalytic layer is based on the total metal content of the catalytic layer. The electrode according to any one of claims 1 to 5, wherein the weight is 10% to 80% by weight.

7. The catalytic layer is made of ruthenium, palladium, rhodium, titanium, niobium, and zirconium. , one or more of hafnium, vanadium, molybdenum, and tungsten Furthermore, it may include; preferably, ruthenium, palladium, rhodium, and titanium in the catalytic layer. niobium, zirconium, hafnium, vanadium, molybdenum, and tungsten The content of each is less than 10% by weight based on the total metal content of the catalytic layer, claim The electrode described in 6.

8. The base material is a valve-type metal or an alloy of a valve-type metal; preferably, the valve-type metal is titanium , tantalum, niobium, zirconium, hafnium, vanadium, molybdenum, and t Selected from one or more of the stenaceous earths; preferably, the base material is metallic titanium or titanium An electrode according to any one of claims 1 to 7, wherein the electrode is an alloy.

9. Any one of claims 1 to 8 as an electrode for electrolysis, electrodialysis or electroplating Use of the electrodes described.

10. The use according to claim 9, wherein the electrode is an oxygen-generating electrode.

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