Ir-Sn oxide-based electrocatalytic anode and preparation method thereof

Abstract

The invention discloses a low-cost Ir-Sn oxide electro-catalytic anode, which is prepared by the following steps: pretreating a titanium substrate to form a rough structure with uniform overall distribution on the surface of the titanium substrate, then coating a mixed metal salt solution of titanium and tantalum on the surface of the titanium substrate, and preparing an intermediate layer with a compact structure by using a thermal decomposition method, thereby obtaining the low-cost Ir-Sn oxide electro-catalytic anode. And finally, circularly coating the surface of the intermediate layer with a noble metal salt solution, and performing high-temperature sintering to form a noble metal oxide catalyst layer. In the precious metal salt solution used by the electrocatalytic anode, the use amount of precious metal with high cost is relatively low, and the production cost can be greatly reduced on the premise of ensuring the electrocatalytic performance and the service life.

Description

Technical Field

[0001] The present invention mainly relates to the technical field of electrocatalytic anodes, and more specifically, to an electrocatalytic anode based on Ir-Sn oxide and a preparation method thereof, which is particularly suitable for applications requiring a long anode service life, strong corrosion resistance, and low current density (<6000A / m 2 ) in the electrocatalytic anode field. Background Art

[0002] At present, metal oxide electrodes formed by coating a titanium-based metal substrate with a precious metal solution are widely used in the fields of chlor-alkali industry, water electrolysis, metal foil production, electroplating, sewage treatment, etc. Among them, titanium-based ruthenium anodes and titanium-based iridium anodes are widely used in industrial production and have the advantages of high current density carrying capacity, low electrode potential, and excellent chemical stability.

[0003] However, the production cost of titanium-based ruthenium anode and titanium-based iridium anode is too high, the oxygen evolution potential is low, the treatment effect in the field of industrial wastewater treatment is not ideal, and the application cost performance is not high. Although the oxygen evolution electrode of titanium-based tin anode has a higher oxygen evolution potential and good wastewater treatment effect, it is easy to produce large internal stress in the working environment, the bonding strength decreases, and it is easy to fall off, resulting in a sharp reduction in working life.

[0004] To this end, the advantages of titanium-based iridium anodes and titanium-based tin anodes are comprehensively utilized, mixed oxide coatings are used, a certain amount of stabilizers are added, and an intermediate layer structure with a stabilizing effect and capable of improving the adhesion of the coating is added, which can effectively solve the problems of high manufacturing cost, low working life, and poor coating adhesion. In view of the above considerations, this invention is specially proposed. Summary of the invention

[0005] In view of the above problems, one of the objects of the present invention is to provide an Ir-Sn oxide-based electrocatalytic anode and a preparation method thereof, which comprehensively utilizes the advantages of titanium-based iridium anodes and titanium-based tin anodes, adds an intermediate layer structure that has a stabilizing effect and can improve the adhesion of the coating, and effectively solves the problems of high manufacturing cost, low working life, and poor coating adhesion of titanium-based anodes.

[0006] In order to comprehensively utilize the advantages of titanium-based iridium-based anodes and titanium-based tin-based anodes, a mixed noble metal oxide catalytic coating is used. In order to improve the bonding force between the catalytic coating and the titanium substrate, an oxide intermediate layer is added between the catalytic coating and the titanium substrate to improve the stability and service life of the Ir-Sn oxide electrocatalytic anode. At the same time, the amount of expensive noble metals used in the noble metal salt solution used in the electrocatalytic anode of the present invention is relatively low, which can greatly reduce the production cost while ensuring the electrocatalytic performance and service life.

[0007] To achieve the above technical objectives, the technical solution of the present invention is implemented as follows: In the first aspect, the present invention provides an Ir-Sn oxide-based electrocatalytic anode, comprising an insoluble metal substrate and an active coating coated on the surface of the substrate, wherein the insoluble metal substrate is a substrate comprising titanium or a titanium alloy, and the active coating comprises at least an underlying oxide intermediate layer and a precious metal oxide catalytic layer, wherein the oxide intermediate layer comprises titanium oxide and tantalum oxide, and the precious metal oxide catalytic layer comprises iridium oxide, tin oxide and tantalum oxide.

[0008] Through intuitive judgment of the SEM surface and cross-sectional morphology of the intermediate layer, it can be observed that the microstructure of the oxide intermediate layer is dense, the surface has no cracks, and it is firmly bonded to the substrate. The dense and firmly bonded intermediate layer structure can prevent the passivation of the substrate titanium during use, the decrease in bonding force, and effectively reduce the probability of the catalyst layer falling off during use. In addition, the intermediate layer structure itself can also stabilize the precious metal oxide catalyst layer and the titanium substrate.

[0009] It should be noted that if the substrate titanium is seriously passivated, or the bonding is not strong enough to cause the catalyst layer to fall off, the anode will fail and its service life will be greatly reduced. Furthermore, since the catalyst layer itself has many cracks of varying sizes, without an intermediate layer, oxygen will pass through the cracks and react with the titanium substrate to passivate it during the use of the anode.

[0010] Finally, due to the large potential difference between the precious metal iridium and tin elements in the catalyst coating and the titanium element of the substrate, direct contact will accelerate the failure of the anode, so the added intermediate layer plays a role of isolation and stabilization to a certain extent.

[0011] In summary, the present invention not only uses iridium and tin oxides as the catalyst layer, but also can comprehensively utilize the advantages of titanium-based iridium anodes and titanium-based tin anodes; it also adds an intermediate layer structure containing titanium and tantalum oxides. By utilizing the dense structure of the intermediate layer, on the one hand, it isolates the direct contact between the precious metal iridium and tin elements in the catalyst coating and the titanium element of the substrate, and on the other hand, it improves the bonding strength between the coatings, avoids the occurrence of anode passivation and oxide layer shedding, and improves the comprehensive performance and manufacturing cost of the anode. In addition, in the provided catalyst layer, a small amount of tantalum is added to improve the comprehensive performance of the coating.

[0012] It should be emphasized here that the present invention utilizes the different advantages of iridium oxide and tin oxide, but the difficulty is that the direct mixing of the two elements will result in certain incompatibility, and the product life is not high. The present invention solves the above-mentioned difficult problems by increasing the dense and firmly bonded intermediate layer structure and adding tantalum elements to the catalytic layer. Specifically, due to the good compatibility between titanium and tantalum, the good transition effect in the coating can significantly improve the stability of the coating, and the intermediate layer structure prepared by titanium and tantalum oxides is dense and compatible, the thermal expansion coefficient of the material is close to that of the substrate, and the natural bonding force is high, which can effectively prevent the substrate from passivation and improve the service life. There is no suitable replacement material for titanium and tantalum here. If other substances are replaced, new incompatibilities will occur, which is determined by the properties of the material itself. In addition, the anodes all work under acidic power-on conditions. Due to the requirements of corrosion resistance, there are not many elements that can be selected. There may be some other substances available, but there will be many new problems.

[0013] In some achievable embodiments of the first aspect, the titanium oxide in the oxide intermediate layer is TiO2; And / or, the tantalum oxide in the oxide intermediate layer is Ta2O5; And / or, the thickness of the oxide intermediate layer is 0.1 μm to 1 μm.

[0014] Since the conductivity of the middle layer is not as good as that of the catalytic layer and it has no catalytic activity under actual working conditions, if it is too thick, it will affect the conductivity between the substrate and the catalytic layer, while if it is too thin, it will not play a stabilizing role and cannot ensure its dense structure.

[0015] In some achievable embodiments of the first aspect, the content of iridium in the noble metal oxide catalyst layer is 1 g / m 2 ~15g / m 2 ; And / or, the content of tin in the noble metal oxide catalyst layer is 1 g / m 2 ~20 g / m 2 .

[0016] At present, the anode with iridium as the main catalyst is basically 20g / m 2 Above, up to 30 g / m 2 The advantages of the motor in this application are: the cost is relatively low compared to the traditional iridium series, the iridium usage is low, the cost is low, the working life is long, and the catalytic activity is good.

[0017] In this application, too much iridium has no practical significance and the cost is too high, while too little iridium cannot achieve the effect of catalytic activity; and if tin is too low, it is necessary to increase the amount of iridium to ensure catalytic activity, and if tin is too high, it will not be much different from the pure tin system, and the disadvantages are obvious.

[0018] And / or, the content of tantalum in the noble metal oxide catalyst layer is 1 g / m 2 ~10g / m 2 Tantalum is not as conductive as iridium and tin. Too much will affect conductivity, while too little will not have a stabilizing effect and will not improve the structure.

[0019] Iridium in conventional noble metal iridium anodes plays the role of providing catalytic activity. The higher the iridium content, the stronger the electrocatalytic ability and the lower the oxygen evolution potential. In the present invention, the anode uses tin to provide the main catalytic activity and regulate the oxygen evolution potential, and iridium plays an auxiliary role, so the iridium content can be reduced.

[0020] The product cost is mainly reflected in the amount of precious metals used. Compared with conventional precious metal catalytic anodes, the iridium content of the present invention is much lower, which naturally reduces the cost. However, due to the low catalytic activity, the oxygen evolution potential does not match the use environment, and the working life will be low. When the iridium is reduced, the catalytic activity will also be reduced simultaneously; however, the present invention can supplement the lost catalytic activity by adding tin elements, and at the same time, it can also adjust the oxygen evolution potential according to the adjustment of the ratio, thereby improving the working life.

[0021] 1. Enhanced stability: The addition of tantalum can increase the durability of the catalyst layer and slow down the changes in the catalyst structure during long-term operation, such as grain growth. Tantalum can form a stable solid solution with Sn and Ir, reducing the shedding and dissolution of the catalyst during the electrochemical reaction.

[0022] 2. Improve corrosion resistance: Tantalum, as a corrosion-resistant metal, can improve the corrosion resistance of the catalyst layer in the electrolyte.

[0023] 3. Increase electrochemical surface area: The addition of tantalum helps to form smaller catalyst particles, thereby increasing the electrochemical active surface area and improving the electrocatalytic efficiency. Microscopically, the addition of tantalum will lead to the formation of more microporous structures, which is conducive to the transmission of electrolyte ions and the adsorption of reactants.

[0024] 4. Improve mechanical strength: The addition of tantalum can improve the bonding force between the catalyst coating and the titanium substrate, reducing the shedding caused by mechanical stress during long-term operation. Tantalum can improve the stress distribution inside the coating and increase the overall mechanical strength of the coating.

[0025] In summary, tantalum improves the overall performance of the catalyst coating through the above-mentioned multiple effects, making it more efficient and stable in electrocatalytic applications.

[0026] In addition, in the study of Sn-Ir-Ta ternary catalyst coating, when the addition amount of tantalum is 1g / m 2 ~10g / m 2When the catalyst coating is used, the catalytic activity, stability and corrosion resistance are optimally balanced, while cost-effectiveness is taken into consideration.

[0027] In some implementable embodiments of the first aspect, the iridium oxide, tin oxide and tantalum oxide in the noble metal oxide catalyst layer are IrO2, SnO2 and Ta2O5, respectively.

[0028] In some implementable embodiments of the first aspect, the grade of titanium or titanium alloy in the insoluble metal substrate is one or more of TA1, TA2, and TC4.

[0029] In a second aspect, the present invention provides a method for preparing an Ir-Sn oxide-based electrocatalytic anode, which is used to prepare the above-mentioned Ir-Sn oxide-based electrocatalytic anode, and the preparation method comprises the following steps: S01: Substrate pretreatment: Surface pretreatment of the titanium substrate is performed to form a certain degree of roughness on the material surface; the pretreated titanium substrate is immersed in boiling hydrochloric acid for etching treatment, and the surface of the treated titanium substrate has a uniform color and a pockmarked surface; S02: preparing the intermediate layer, coating the surface of the titanium substrate with a base liquid, wherein the base liquid is a solution containing titanium oxide and tantalum oxide, and after coating, performing heat preservation treatment in a sintering furnace, cooling down to room temperature after being taken out of the furnace, and obtaining an oxide intermediate layer supported on the surface of the titanium substrate; S03: Preparation of a noble metal oxide catalyst layer, coating the surface of the oxide intermediate layer with a topcoat liquid, wherein the topcoat liquid is a solution containing iridium oxide, tin oxide and tantalum oxide. After coating, the layer is subjected to heat preservation treatment in a sintering furnace, and then cooled to room temperature after being taken out of the furnace to obtain an Ir-Sn oxide-based electrocatalytic anode.

[0030] In some achievable methods of the second aspect, the titanium substrate is surface pretreated by laser shock peening; And / or, the impact energy of the laser impact is 2-12 J, and the number of impacts is 1-5 times; And / or, the roughness index of the substrate surface after laser shock peening treatment is: Ra>6μm, Rz>20μm.

[0031] In the pretreatment of substrates, the existing technology mostly uses sandblasting. The use of laser strengthening will produce a uniform and rough microstructure on the surface of the substrate, which will make the adhesion of the entire coating higher. In addition, if the impact energy of the laser shock is too high or the number of times is too many, it will lead to increased loss of the substrate and increased oxidation of the titanium substrate surface, affecting the parameters of the subsequent hydrochloric acid etching; if the impact energy of the laser shock is too low or the number of times is too few, it will not achieve the effect of improving the adhesion of the coating.

[0032] In the present invention, laser strengthening is used to produce uneven pits on the surface of the substrate, which can better adhere to the intermediate layer and the catalyst coating and improve their bonding force (also known as adhesion). The laser pre-treated titanium substrate is placed in hydrochloric acid for etching, the purpose of which is to remove the oxide film on the surface of the substrate, so that the surface of the titanium substrate forms a microscopically irregular pockmarked surface, thereby increasing the specific surface area of ​​the substrate. In simple terms, it can make more coating elements attached per unit area.

[0033] In some preferred embodiments, the mass concentration of the hydrochloric acid in the etching treatment is 5% to 25%, and the etching time is 5 min to 30 min.

[0034] If the mass concentration of hydrochloric acid is too high or the etching time is too long, not only the cost of acid and the cost of treating acid mist will increase, but also the corrosion and loss of the titanium substrate will be aggravated (excessive aggravation will affect the size and the number of times the titanium substrate is reused); if the mass concentration of hydrochloric acid is too low or the etching time is too short, the etching will not be thorough, the oxides on the surface of the titanium substrate will not be completely removed, and the pockmarked surface cannot be formed, and the effect of increasing the specific surface area cannot be achieved.

[0035] In some achievable methods of the second aspect, in step S02, during the insulation process in the sintering furnace, a thermal decomposition reaction occurs on the surface of the substrate, the insulation temperature in the sintering furnace is 400~600°C, and the insulation time each time is 20min~100min. After being taken out of the furnace and cooled to room temperature, the above coating-insulation-cooling steps are repeated 2~6 times until the thickness of the oxide intermediate layer reaches 0.1μm~1μm.

[0036] In some preferred embodiments, the tantalum source in the base solution is selected from any one of tantalum pentachloride, tantalum butanediol, and tantalum ethoxide. Under the sintering parameters of the present invention, if the tantalum source is improperly selected, the oxide intermediate layer cannot be formed, or is not formed completely, and the purpose of the present invention to improve the coating adhesion and service life cannot be achieved.

[0037] In some achievable methods of the second aspect, in step S03, during the insulation process in the sintering furnace, a thermal decomposition reaction occurs on the surface of the substrate, the insulation temperature in the sintering furnace is 450-650°C, and the insulation time each time is 10 min-60 min. After being taken out of the furnace and cooled to room temperature, the above coating-insulation-cooling steps are repeated 5-30 times.

[0038] In some achievable methods of the second aspect, the molar mass ratio of iridium, tin, and tantalum in the surface solution is 1: (1-10): (0.1-1). First, the molar mass ratio of iridium, tin, and tantalum will directly affect the catalytic activity and the oxygen evolution potential, and secondly, it will also affect the service life of the anode. In addition, the change in the ratio of the precious metal iridium will also affect the manufacturing cost of the anode.

[0039] Beneficial effects of the present invention: (1) The low-cost Ir-Sn oxide electrocatalytic anode provided by the present invention, compared with the currently common titanium-based IrO2-Ta2O5 mixed oxide anode, has greatly reduced product cost and increased service life while ensuring greater electrocatalytic activity and excellent chemical stability; compared with the tin dioxide titanium anode commonly used in the fields of sewage treatment, the present invention can greatly improve the bonding strength between the coating and the titanium substrate, has a lower oxygen evolution potential, and has a good wastewater treatment effect at the same current density.

[0040] (2) The present invention not only uses iridium and tin oxides as the catalyst layer, but also makes comprehensive use of the advantages of titanium-based iridium anodes and titanium-based tin anodes; it also adds an intermediate layer structure containing titanium and tantalum oxides. The dense structure of the intermediate layer is used to isolate the direct contact between the precious metal iridium and tin elements in the catalyst coating and the titanium element of the substrate, and to improve the bonding strength between the coatings, avoid anode passivation and oxide layer shedding, and improve the comprehensive performance and manufacturing cost of the anode. In addition, a small amount of tantalum is added to the provided catalyst layer to improve the comprehensive performance of the coating.

[0041] (3) Product cost is mainly reflected in the amount of precious metals used. Compared with conventional precious metal catalytic anodes, the iridium content of the present invention is much lower, which naturally reduces the cost. However, due to the low catalytic activity, the oxygen evolution potential does not match the use environment, and the working life will be short. When the iridium is reduced, the catalytic activity will also be reduced simultaneously; however, the present invention can supplement the lost catalytic activity by adding tin elements, and at the same time, it can also adjust the oxygen evolution potential according to the adjustment of the ratio, thereby improving the working life.

[0042] The present invention will be explained in detail below with reference to the accompanying drawings and specific embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 This is a schematic diagram of the structure of an Ir-Sn oxide electrocatalytic anode according to an embodiment of the present invention; Figure 2 This is a surface SEM morphology of the low-cost Ir-Sn oxide electrocatalytic anode in Example 1 of the present invention.

[0044] Numbers in the figure: 1. Titanium substrate; 2. Oxide intermediate layer; 3. Precious metal oxide catalyst layer. DETAILED DESCRIPTION

[0045] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present invention.

[0046] Example 1: The present invention aims to solve the problems of high cost, insufficient working life, poor adhesion, etc. of the current titanium anode, and provides a low-cost Ir-Sn oxide electrocatalytic anode. The titanium substrate is pretreated to form a rough structure with overall uniform distribution on its surface, and then a mixed metal salt solution of titanium, tin and tantalum is coated on the surface of the titanium substrate, and a dense structure intermediate layer is prepared by thermal decomposition method, and finally a low-proportion noble metal salt solution is cyclically coated on the surface of the intermediate layer, and a noble metal oxide catalyst layer is formed by high-temperature sintering.

[0047] This embodiment provides an electrocatalytic anode based on Ir-Sn oxide, such as Figure 1 As shown, the anode includes a titanium substrate 1, an oxide intermediate layer 2 and a noble metal oxide catalyst layer 3 arranged in sequence from the inside to the outside; the surface SEM morphology is shown in Figure 2 The specific preparation process of the electrocatalytic anode is as follows: S01: Substrate pretreatment: laser shock strengthening was performed on an industrial titanium plate (made of TA1) with a specification of 200mm*200mm*6mm. The impact energy was 5J and the number of impacts was 3 times. The titanium plate after laser shock strengthening was immersed in 25%wt HCl above 95°C for acid etching for 15 minutes, then rinsed with a water gun, dried and set aside.

[0048] S02: Preparation of the intermediate layer: dilute hydrochloric acid is used as the solvent, and a certain proportion of TiCl4 and TaCl5 are added. After fully stirring, an intermediate layer coating liquid of a certain concentration is obtained. The intermediate layer coating liquid is fully coated on the surface of the etched titanium plate, dried in an oven at 90 °C for 15 min, and sintered in a sintering furnace at 450 °C for 20 min. The coating-drying-sintering process is repeated 5 times and then set aside.

[0049] S03: Preparation of precious metal oxide catalyst layer, using n-butanol-isopropanol (1:1) mixed solution as solvent, adding H2IrCl6 and SnCl4 mixed in a certain proportion, and fully dissolving to obtain a coating solution with a molar mass ratio of Ir and Sn of 1:5, wherein the concentration of Ir in the coating solution is 0.1 mol / L. The coating solution is evenly coated on the titanium substrate with an intermediate layer, dried in an oven at 90°C for 15 min after coating, and then sintered in a furnace at 500°C for 35 min. Repeat the coating 15 times to finally obtain a coated titanium anode with a structure of Ti / TiO2+Ta2O5 / IrO2+SnO2+Ta2O5, wherein the iridium content in the coating is 10 g / m 2 .

[0050] Example 2: This example provides a method for preparing an electrocatalytic anode based on Ir-Sn oxide. The preparation steps are basically the same as those in the preparation method of Example 1, except that during substrate pretreatment, the impact energy of the laser shock is 9 J and the number of shocks is 4.

[0051] Example 3: This example provides a method for preparing an Ir-Sn oxide-based electrocatalytic anode, and its preparation steps are basically the same as those in Example 1, except that when preparing the oxide intermediate layer, the sintering temperature of the sintering furnace is 520°C and the sintering time is 80 minutes.

[0052] Example 4: This example provides a method for preparing an Ir-Sn oxide-based electrocatalytic anode, and its preparation steps are basically the same as those in the preparation method of Example 1, except that when preparing the noble metal oxide catalyst layer, the coating number is 10 times.

[0053] Example 5: This example provides a method for preparing an Ir-Sn oxide electrocatalytic anode, and its preparation steps are basically the same as those in the preparation method of Example 1, except that when preparing the precious metal oxide catalyst layer, the sintering temperature is 480°C and the sintering time is 60 minutes.

[0054] Comparative Example 1: This comparative example provides a method for preparing a Ti / IrO2+SnO2 electrocatalytic anode without an intermediate layer, which is basically the same as the method in Example 1, except that the anode of this comparative example does not contain an intermediate layer, and the surface precious metal oxide catalytic layer is directly prepared after the substrate is pretreated, and finally an anode with a structure of Ti / IrO2+SnO2+Ta2O5 is obtained.

[0055] Comparative Example 2: This comparative example provides a method for preparing an IrO2+Ta2O5 electrocatalytic anode, and its preparation steps are basically the same as those in the preparation method of Example 1, except that the surface noble metal catalyst layer prepared in this comparative example is different, and its preparation steps are as follows: Using a mixture of n-butanol and isopropanol (1:1) as the solvent, add H2IrCl6 and SnCl4 mixed in a certain proportion, and after sufficient dissolution, obtain a coating solution with a molar ratio of Ir and Ta of 7:3, wherein the concentration of Ta in the coating solution is 0.1 mol / L. The coating solution is evenly coated on a titanium plate with an intermediate layer, dried in an oven at 90 °C for 15 min after coating, and then sintered in a furnace at 520 °C for 20 min. Repeat the coating 25 times to finally obtain a titanium anode with a structure of Ti / TiO2+Ta2O5 / IrO2+Ta2O5, wherein the iridium content in the precious metal catalyst layer is 30g / m 2 .

[0056] Comparative Example 3: This comparative example provides a method for preparing a SnO2+Ta2O5 electrocatalytic anode, which is basically the same as the method in Example 1, except that the anode catalytic layer of this comparative example does not contain iridium, and the final anode obtained has a structure of Ti / TiO2+Ta2O5 / SnO2+Ta2O5.

[0057] Comparative Example 4: This comparative example provides a method for preparing an electrocatalytic anode based on Ir-Sn oxide, which is basically the same as the method in Example 1, except that the anode catalyst layer of this comparative example does not contain tantalum, and finally an anode with a structure of Ti / TiO2+Ta2O5 / IrO2+SnO2 is obtained.

[0058] Comparative Example 5: This comparative example provides a method for preparing an electrocatalytic anode based on Ir-Sn oxide, which is basically the same as the method in Example 1, except that the intermediate layer of this comparative example does not contain tantalum, and finally an anode with a structure of Ti / IrO2+SnO2+Ta2O5 is obtained.

[0059] Comparative Example 6: This comparative example provides a method for preparing an electrocatalytic anode based on Ir-Sn oxide, which is basically the same as the method in Example 1, except that the intermediate layer of this comparative example does not contain titanium, and the final anode obtained has a structure of Ta2O5 / IrO2+SnO2+Ta2O5.

[0060] The electrodes prepared in the above Examples 1-5 and Comparative Examples 1-6 were subjected to electrode potential test, accelerated life test and coating adhesion test, wherein the electrode potential test conditions are as follows: Current density: 50 A / m 2 Temperature: 25 ℃ Electrolyte: 150 g / L sulfuric acid solution Reference electrode: Mercurous sulfate Cathode: Zr Pole distance: 1 cm The accelerated life test conditions are as follows: Current density: 5A / cm 2 Electrolysis temperature: 60 ℃ Electrolyte: 150 g / L sulfuric acid solution Cathode: Ti Pole distance: 1 cm The film adhesion test was performed using an automatic scratch tester, and the test conditions were as follows: Detection mode: Acoustic emission Loading load: 100 N Loading method: One-way continuous loading Scratch length: 6 mm Loading rate: 60 N / min The accelerated life test takes the end point of the life when the electrolysis voltage increases by 1 V compared to the initial voltage, and the bonding strength test result is the critical load value at which the coating begins to break. The results are shown in Table 1.

[0061] Table 1 is a performance comparison of Examples 1-5 and Comparative Examples 1-6 Sample No. Compared with Example 1, the preparation process changes Electrode potential (V) Lifespan (h) Coating bonding strength (N) <![CDATA[Anode iridium content (g / m 2 )]]> Example 1 / 0.92 1320 50 7.4~7.6 Example 2 Laser shock parameters are different 0.92 1560 65 7.4~7.6 Example 3 Different sintering parameters for the middle layer 0.91 1386 55 7.4~7.6 Example 4 Different number of surface coatings 0.94 1157 66 4.9~5.1 Example 5 Different surface sintering parameters 0.93 1260 62 7.4~7.6 Comparative Example 1 No intermediate layer 0.92 737 30 7.4~7.6 Comparative Example 2 Different surface 0.91 1020 40 29.8~30.2 Comparative Example 3 The surface does not contain iridium 1.08 340 55 0 Comparative Example 4 The surface layer does not contain tantalum 0.90 970 47 7.4~7.6 Comparative Example 5 The intermediate layer does not contain tantalum 0.91 710 28 7.4~7.6 Comparative Example 6 The middle layer does not contain titanium 0.91 990 40 7.4~7.6 Comparing Examples 1-5 with Comparative Example 2, it can be seen that the Ir-Sn oxide anode can effectively improve the bonding force between the coating and the substrate; under the premise of greatly reducing the amount of precious metal iridium, it can also effectively improve its working life, and the increase in electrode potential is only 0~3V. Comparing Examples 1-5 with Comparative Examples 1 and 4, it can be seen that the introduction of the oxide intermediate layer greatly improves the stability of the coating, significantly improves the working life, and tantalum plays a major role. Comparing Examples 2-4 with Example 1, it can be seen that by adjusting the parameters of each step in the process, further improvements in performance such as electrode potential, working life, and coating bonding can be achieved. Comparing Examples 1-5 with Comparative Example 3, it can be seen that the presence of iridium in the surface catalytic layer can reduce its potential and increase its service life. Comparing Examples 1-5 with Comparative Example 4, it can be seen that the presence of tantalum in the surface catalytic layer can increase its service life and coating bonding. Comparing Examples 1-5 with Comparative Examples 5 and 6, it can be seen that the absence of any element of titanium or tantalum in the intermediate layer will affect the coating bonding and working life.

[0062] In summary, with the help of the above technical solution of the present invention, the low-cost Ir-Sn oxide electrocatalytic anode proposed can greatly reduce the manufacturing cost of titanium electrodes and increase the working life of electrodes by reducing the amount of precious metal tin and introducing the addition of tin elements. It has broad application prospects in the fields of metal surface treatment, sewage treatment, electrochemical metallurgy, etc.

[0063] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

[0064] The above is an exemplary description of the present invention in combination with the accompanying drawings. It is obvious that the specific implementation of the present invention is not limited to the above-mentioned method. As long as such non-substantial improvements are made by adopting the method concept and technical solution of the present invention, or the concept and technical solution of the present invention are directly applied to other occasions without improvement, they are all within the protection scope of the present invention.

Claims

1. An electrocatalytic anode based on Ir-Sn oxide, It is characterized in that The invention comprises an insoluble metal substrate and an active coating coated on the surface of the substrate, wherein the insoluble metal substrate is a substrate comprising titanium or a titanium alloy, and the active coating comprises at least an underlying oxide intermediate layer (2) and a noble metal oxide catalytic layer (3), wherein the oxide intermediate layer comprises titanium oxide and tantalum oxide, and the noble metal oxide catalytic layer comprises iridium oxide, tin oxide and tantalum oxide.

2. The Ir-Sn oxide-based electrocatalytic anode according to claim 1, It is characterized in that The titanium oxide in the oxide intermediate layer is TiO 2 ; And / or, the tantalum oxide in the oxide intermediate layer is Ta 2 O 5 ; And / or, the thickness of the oxide intermediate layer is 0.1 μm to 1 μm.

3. The Ir-Sn oxide-based electrocatalytic anode according to claim 1, It is characterized in that The iridium content in the noble metal oxide catalyst layer is 1 g / m 2 ~15g / m 2 ; And / or, the content of tin in the noble metal oxide catalyst layer is 1 g / m 2 ~20 g / m 2 ; And / or, the content of tantalum in the noble metal oxide catalyst layer is 1 g / m 2 ~10g / m 2 .

4. The Ir-Sn oxide-based electrocatalytic anode according to claim 1 or 3, It is characterized in that The iridium oxide, tin oxide and tantalum oxide in the noble metal oxide catalyst layer are IrO 2 SnO 2 and Ta 2 O 5 .

5. The Ir-Sn oxide-based electrocatalytic anode according to claim 1, It is characterized in that The grades of titanium or titanium alloy in the insoluble metal substrate are one or more of TA1, TA2 and TC4.

6. A method for preparing an electrocatalytic anode based on Ir-Sn oxide, It is characterized in that For preparing the Ir-Sn oxide-based electrocatalytic anode according to any one of claims 1 to 5, the preparation method comprises the following steps: S01: Substrate pretreatment: Surface pretreatment of the titanium substrate is performed to form a certain degree of roughness on the material surface; the pretreated titanium substrate is immersed in boiling hydrochloric acid for etching treatment, and the surface of the treated titanium substrate has a uniform color and a pockmarked surface; S02: preparing the intermediate layer, coating the surface of the titanium substrate with a base liquid, wherein the base liquid is a solution containing titanium oxide and tantalum oxide, and after coating and drying, performing heat preservation treatment in a sintering furnace, cooling down to room temperature after being taken out of the furnace, and obtaining an oxide intermediate layer supported on the surface of the titanium substrate; S03: Preparation of a precious metal oxide catalyst layer, coating the surface of the oxide intermediate layer with a surface liquid, wherein the surface liquid is a solution containing iridium oxide, tin oxide and tantalum oxide. After coating and drying, the surface liquid is kept in a sintering furnace, and then cooled to room temperature after being taken out of the furnace to obtain an Ir-Sn oxide-based electrocatalytic anode.

7. The method for preparing an Ir-Sn oxide electrocatalytic anode according to claim 6, It is characterized in that Surface pretreatment of titanium substrate using laser shock peening; And / or, the impact energy of the laser impact is 2-12 J, and the number of impacts is 1-5 times; And / or, the roughness index of the substrate surface after laser shock peening treatment is: Ra>6μm, Rz>20μm; And / or, the mass concentration of the hydrochloric acid in the etching treatment is 5% to 25%, and the etching time is 5 min to 30 min.

8. The method for preparing an Ir-Sn oxide electrocatalytic anode according to claim 6, It is characterized in that In step S02, during the heat preservation process in the sintering furnace, a thermal decomposition reaction occurs on the surface of the substrate. The heat preservation temperature in the sintering furnace is 400-600°C, and the heat preservation time is 20min-100min each time. After being taken out of the furnace, the substrate is cooled to room temperature, and the above coating-heat preservation-cooling steps are repeated 2-6 times until the thickness of the oxide intermediate layer reaches 0.1μm-1μm. And / or, the tantalum source in the base solution is selected from any one of tantalum pentachloride, tantalum butanediol and tantalum ethoxide.

9. The method for preparing an Ir-Sn oxide electrocatalytic anode according to claim 6, It is characterized in that In step S03, during the insulation process in the sintering furnace, a thermal decomposition reaction occurs on the surface of the substrate. The insulation temperature in the sintering furnace is 450-650°C, and the insulation time is 10-60 minutes each time. After being taken out of the furnace, it is cooled to room temperature, and the above coating-insulation-cooling steps are repeated 5-30 times.

10. The method for preparing an Ir-Sn oxide electrocatalytic anode according to any one of claims 6 to 9, It is characterized in that The molar mass ratio of iridium, tin and tantalum in the surface liquid applied each time is consistent, and Ir:Sn:Ta=1:(1~10):(0.1~1).

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