阅读说明：本技术 一种金属氧化物涂层电极制备方法 (Preparation method of metal oxide coating electrode ) 是由 刘峰 许立坤 刘越仁 张迪 于 2021-10-15 设计创作，主要内容包括：本发明属于电化学技术领域,具体涉及一种金属氧化物涂层电极制备方法,将涂敷前驱体涂液的金属基体置于等离子体处理腔体内,在同一系统内实现前驱体涂液的烘干、分解和涂层烧结步骤,利用等离子体强的氧化性,在烘干和烧结过程中增强涂层的氧化程度,促进晶体结构的形成,提高氧化物涂层的性能,达到提高处理效率和电极电化学性能的目的；其步骤简单,原理科学可靠,采用加温和等离子体联合处理方法烘干前驱体涂液,采用高温烧结和等离子体联合处理方法烧结涂层,烘干和烧结在同一个系统内完成,通过控制加热的温度和处理的时间实现烘干和烧结,使电极的电化学催化活性大幅度增加,在相同电压的条件下,获得更大的电流密度,提高了使用效率。(The invention belongs to the technical field of electrochemistry, and particularly relates to a preparation method of a metal oxide coating electrode, wherein a metal substrate coated with precursor coating liquid is placed in a plasma processing cavity, the steps of drying, decomposing and coating sintering of the precursor coating liquid are realized in the same system, the strong oxidability of plasma is utilized, the oxidation degree of the coating is enhanced in the drying and sintering processes, the formation of a crystal structure is promoted, the performance of the oxide coating is improved, and the purposes of improving the processing efficiency and the electrochemical performance of the electrode are achieved; the method has the advantages of simple steps and scientific and reliable principle, the precursor coating liquid is dried by adopting a heating and plasma combined treatment method, the coating is sintered by adopting a high-temperature sintering and plasma combined treatment method, the drying and sintering are finished in the same system, the drying and sintering are realized by controlling the heating temperature and the treatment time, the electrochemical catalytic activity of the electrode is greatly increased, higher current density is obtained under the condition of the same voltage, and the use efficiency is improved.)

1. A preparation method of a metal oxide coating electrode is characterized in that the metal oxide coating electrode is prepared based on a plasma-assisted sintering method.

2. The method for preparing the metal oxide coating electrode according to claim 1, wherein the process comprises the following steps: firstly, coating a precursor coating liquid on a pretreated metal substrate, then placing the metal substrate coated with the precursor coating liquid in a plasma processing cavity, carrying out plasma processing for 10min at the temperature of 100-120 ℃ and under the condition of introducing mixed gas, drying a solvent in the precursor coating liquid to enable the precursor to be in a precursor stateForming a coating on a metal substrate by solute in the liquid coating, and finally sintering the coating at high temperature, wherein in the sintering process, the coating is treated by plasma discharge to prepare the RuO for electrolytic antifouling₂-IrO₂Iro for electrode and cathodic protection₂-Ta₂O₅Various systems of metal oxide coated electrodes.

3. The method of claim 2, wherein the mixed gas comprises argon and oxygen at a flow rate of 10 sccm.

4. The preparation method of the metal oxide coating electrode according to claim 2, characterized in that the specific process comprises:

(1) pretreating a metal matrix: firstly, carrying out alkali washing on a metal matrix with a plate-shaped structure by using a mixed solution at the temperature of 80 ℃, secondly, washing the metal matrix by using deionized water, carrying out ultrasonic treatment for 10min, then, placing the metal matrix in a boiled oxalic acid aqueous solution with the mass percentage concentration of 10% for pickling for 2h to remove a passivation film on the surface of the metal matrix, and finally, sequentially washing in the deionized water and absolute ethyl alcohol to obtain a pretreated metal matrix, and soaking in the absolute ethyl alcohol for later use;

(2) preparing a metal oxide electrode: firstly, uniformly coating a precursor solution on the surface of a pretreated metal substrate, placing the pretreated metal substrate in a plasma processing cavity, vacuumizing, and introducing Ar₂And O₂The method comprises the steps of applying 4KV high voltage and 80mA current to carry out plasma glow discharge by adopting microwave plasma discharge equipment, then drying for 10min at 120 ℃ to evaporate a solvent in a precursor solution to form a coating on a solute in the precursor solution, finally raising the temperature to a sintering temperature, keeping the temperature for 10min, cooling to room temperature along with a furnace, repeating the steps of drying, sintering and cooling for a plurality of times to reach a set coating loading capacity, wherein the sintering time for the last time is 1h, and the precursor coating liquid is ensured to be fully oxidized and decomposed.

5. The method of claim 2 or 4, wherein the solvent of the precursor solution is n-butanol or isopropanol, and the solute is IrO₂、RuO₂、Ta₂O₅、SbO₂、TiO₂、SnO₂The total concentration of solute metal ions is 0.3 mol/L.

6. The method for preparing the metal oxide coating electrode according to claim 4, wherein the mass percentage concentration of the mixed solution is 8%, and the time of alkaline washing is 1 h; the mass percentage concentration of the oxalic acid aqueous solution is 10 percent, and the pickling time is 2 hours.

7. The method of claim 5, wherein the precursor solution comprises RuO₂-IrO₂System and IrO₂-Ta₂O₅And (4) preparing the system.

8. The method of claim 6, wherein the solvent of the mixed solution is water and the solute is NaPO₄、Na₂CO₃And NaOH, NaPO₄、Na₂CO₃And NaOH at a mass ratio of 45:25: 4.

The technical field is as follows:

the invention belongs to the technical field of electrochemistry, and particularly relates to a preparation method of a metal oxide coating electrode, which is used for preparing the metal oxide coating electrode suitable for electrochemical engineering such as seawater electrolysis, sewage degradation, marine organism fouling prevention, cathode protection and the like through plasma assistance.

Background art:

a metal oxide electrode (DSA) is a novel insoluble electrode, has good electrocatalytic activity and Stable electrochemical performance as a representative of the insoluble electrode, has been widely applied in the fields of chlor-alkali industry, cathodic protection, electroplating industry, hydrometallurgy, organic synthesis, water treatment and the like, and is an ideal electrode material nowadays.

The preparation method of the titanium-based oxide electrode in the metal oxide anode comprises a sol-gel method, a thermal decomposition method, an ion sputtering method, an electrodeposition method and a solid phase synthesis method, wherein the thermal decomposition method is a method commonly used in a laboratory and is also a method with highest cost performance and widest application in industrial production. The thermal decomposition method comprises the specific process steps of dissolving a precursor in an organic solvent, uniformly coating the precursor on a pretreated titanium substrate, heating to evaporate the solvent, calcining at high temperature in air to form a deposit, and repeatedly brushing and sintering to form a thick conductive coating. The thermal decomposition method has the advantages of simplicity, practicability, low equipment cost and wide application range, and improves the electrocatalytic performance and stability of the coating through the optimization of a substrate pretreatment process, the proportion of coating liquid, the selection of a solvent, the size of loading and the thermal decomposition process.

In the preparation process of the metal oxide anode, drying and thermal oxidation sintering treatment are necessary procedures: the drying is to volatilize the solvent, and is generally preferably carried out slowly; the thermal oxidation sintering treatment is to oxidize and decompose the metal compound deposited on the substrate to form an oxide. The sintering process has an important influence on the quality of the coating, the sintering temperature and the sintering time have a great influence on the internal structure (such as grain size and molecular arrangement) of the coating, and the composition and the structure of the coating directly influence the electrochemical performance of the electrode. At present, the optimized temperature of the sintering process is 450-.

The preparation method of the metal oxide coating anode disclosed in the Chinese patent 201510284290.1 is characterized by comprising the following three steps of substrate pretreatment, coating liquid preparation and coating anode preparation: (1) substrate pretreatment: selecting an industrial pure titanium plate as a substrate material, placing the substrate in an oxalic acid water solution with the mass percentage concentration of 10% and the temperature of 90-100 ℃ after the substrate is subjected to conventional sand blasting treatment, carrying out acid etching for 1 hour, taking out the substrate when the surface roughness Ra of the substrate is 1.5-3.5 mu m, carrying out ultrasonic cleaning on the substrate by using distilled water, then cleaning the substrate by using industrial alcohol for 2-3 times, drying the substrate, immersing the substrate in an absolute alcohol cylinder, and carrying out sealed preservation for later use to finish substrate pretreatment; (2) and preparing a coating solution: measuring IrO with corresponding volume according to the requirement of the magnitude of the molar ratio of Ir, Ru, Ta, Sb, Ti and Sn in the metal oxide coating₂、RuO₂、Ta₂O₅、SbO₂、TiO₂And SnO₂Mixing the aqueous solution to obtain a mixed solution, and adding the mixed solution according to the ratio of 1: 1.5-3, adding 99% of n-butanol aqueous solution by mass percentage, adjusting the total concentration of metal ions in the mixed solution to 0.2-0.35mol/L, and then magnetically stirring the mixed solution until the mixed solution is uniformly mixed to prepare coating solution; (3) and preparing a coating anode: in the conventional equipment, the plasma discharge current is set to be 3-4A, the moving speed of a jet gun is 100-600mm/min, the coating liquid prepared in the step (2) is sprayed on the surface of the substrate pretreated in the step (1) in a covering mode, and then the substrate is subjected to coating treatmentDrying in a drying box at 100 deg.C for 10min to form a coating on the surface of the substrate, and oxidizing the surface of the coating by plasma jet discharge; repeating the steps of spraying, drying and plasma oxidation for 6-8 times, and then putting the substrate into a sintering furnace at 550 ℃ for sintering for 1-1.2h to finish the preparation of the coating anode; the substrate is made of metal titanium with the mass percentage purity of more than 99%, and the shape of the substrate comprises a net shape, a plate shape, a tubular shape and a rod shape; the metal oxide coating is prepared from IrO with a set weight ratio₂、RuO₂、Ta₂O₅、SbO₂、TiO₂、SnO₂The single component or the multiple components are compounded; the normal pressure plasma is used for coating post-treatment to promote the decomposition of coating liquid and the formation of oxide, and the electrochemical performance of the oxide coating is improved through high-temperature sintering. Further, Japanese patent laid-open No. 5-156480 discloses an oxide electrode prepared by spraying a sol on the surface of a titanium substrate by a sol method using plasma spraying. The patent method relates to the links of coating liquid coating and coating liquid drying decomposition, and has the problems of low deposition rate, coating liquid dissipation loss and the like. Therefore, the preparation efficiency and performance are improved, and the preparation and use cost is reduced.

The invention content is as follows:

the invention aims to overcome the defects in the prior art and seek to design a preparation method of a metal oxide coating electrode so as to prepare an electrode with catalytic activity and electric capacity meeting the requirements of a high-performance oxide coating electrode.

In order to achieve the purpose, the preparation method of the metal oxide coating electrode, which is related by the invention, is based on a plasma-assisted sintering method to prepare the metal oxide coating electrode, and the technical process is as follows: firstly, coating a precursor coating liquid on a pretreated metal substrate, then placing the metal substrate coated with the precursor coating liquid in a plasma processing cavity, carrying out plasma processing for 10min at the temperature of 100-120 ℃ and under the condition of introducing mixed gas (composed of argon and oxygen with gas flow of 10sccm respectively), drying a solvent in the precursor coating liquid to enable a solute in the precursor coating liquid to form a coating on the metal substrate, and finally, sintering the coating at high temperature, wherein the coating is sintered in the sintering processPlasma discharge treatment of the coating to produce RuO including electrolytic antifouling₂-IrO₂Iro for electrode and cathodic protection₂-Ta₂O₅Various systems of metal oxide coated electrodes.

The specific process of the preparation method of the metal oxide coating electrode comprises the following steps:

(1) pretreating a metal matrix: firstly, carrying out alkaline washing on a metal matrix with a plate-shaped structure for 1 hour by using a mixed solution with the mass percentage concentration of 8% at the temperature of 80 ℃, secondly, washing the metal matrix with deionized water, then carrying out ultrasonic treatment for 10min, then, placing the metal matrix in a boiled oxalic acid aqueous solution with the mass percentage concentration of 10% for carrying out acid washing for 2 hours to remove a passivation film on the surface of the metal matrix, and finally, sequentially washing in the deionized water and absolute ethyl alcohol to obtain a pretreated metal matrix, and soaking the pretreated metal matrix in the absolute ethyl alcohol for later use; wherein the solvent of the mixed solution for alkali washing is water, and the solute is NaPO₄、Na₂CO₃And NaOH, NaPO₄、Na₂CO₃The mass ratio of NaOH to NaOH is 45:25: 4;

(2) preparing a metal oxide electrode: firstly, uniformly coating a precursor solution on the surface of a pretreated metal substrate, placing the pretreated metal substrate in a plasma processing cavity, vacuumizing, and introducing Ar₂And O₂Applying 4KV high-voltage 80mA current to perform plasma glow discharge by adopting microwave plasma discharge equipment, then drying for 10min at the temperature of 120 ℃ to evaporate a solvent in a precursor solution to form a coating on a solute in the precursor solution, finally raising the temperature to a sintering temperature, keeping the temperature for 10min, cooling to room temperature along with a furnace, repeating the steps of drying, sintering and cooling for a plurality of times to reach the set coating loading capacity, wherein the sintering time for the last time is 1h, and ensuring that the precursor coating solution is sufficiently oxidized and decomposed; the solvent of the precursor solution is n-butanol or isopropanol, and the solute is IrO₂、RuO₂、Ta₂O₅、SbO₂、TiO₂、SnO₂Of single or multiple components, of solute metal ionsTotal concentration of 0.3mol/L, e.g. RuO₂-IrO₂System and IrO₂-Ta₂O₅And (4) preparing the system.

Compared with the prior art, the invention has the outstanding innovation points that plasma discharge is implemented in the high-temperature sintering process, the metal substrate coated with the precursor coating liquid is placed in the plasma processing cavity, the steps of drying, decomposing and coating sintering of the precursor coating liquid are realized in the same system, the oxidation degree of the coating is enhanced in the drying and sintering processes by utilizing the strong oxidability of the plasma, the formation of a crystal structure is promoted, the performance of an oxide coating is improved, and the purposes of improving the processing efficiency and the electrochemical performance of an electrode are achieved; the method has the advantages of simple steps and scientific and reliable principle, the precursor coating liquid is dried by adopting a heating and plasma combined treatment method, the coating is sintered by adopting a high-temperature sintering and plasma combined treatment method, the drying and sintering are finished in the same system, the drying and sintering are realized by controlling the heating temperature and the treatment time, the electrochemical catalytic activity of the electrode is greatly increased, higher current density is obtained under the condition of the same voltage, and the use efficiency is improved.

Description of the drawings:

FIG. 1 is a schematic comparison of polarization curves for metal oxide coated electrodes prepared by plasma assisted sintering and thermal decomposition according to the present invention.

FIG. 2 is a comparison of cyclic voltammetry curves for metal oxide coated electrodes prepared by plasma assisted sintering and thermal decomposition according to the present invention.

FIG. 3 is a comparative illustration of the electrical capacity of the metal oxide coated electrode prepared by the plasma assisted sintering process and the thermal decomposition process according to the present invention.

The specific implementation mode is as follows:

the invention is further described below by way of an embodiment example in conjunction with the accompanying drawings.

Example 1:

the specific process of the preparation method of the metal oxide coating electrode related to the embodiment comprises the following steps:

(1)TA₂pretreatment of a matrix: firstly, the mass is usedTA of plate-like structure at 80 deg.C in a mixed solution with a ratio of 8%₂The substrate was subjected to alkaline washing for 1h and, secondly, the TA was rinsed with deionized water₂Post-sonication of the matrix for 10min, followed by TA₂Pickling the substrate in 10 wt% concentration boiled oxalic acid solution for 2 hr to eliminate TA₂Finally, cleaning the passive film on the surface of the substrate by using acetone, deionized water or absolute ethyl alcohol in sequence to obtain the pretreated TA₂A substrate, which is immersed in absolute ethyl alcohol for standby;

(2)IrO₂-Ta₂O₅preparing an electrode: first, chloroiridic acid and TaCl are mixed₅Mixing n-butanol solution and hydrochloric acid, dissolving in n-butanol (Ir and Ta at a mass ratio of 7:3) to obtain coating solution with concentration of 0.3M, stirring for 30min to obtain precursor coating solution, and uniformly coating the precursor solution on the pretreated TA₂Placing the surface of the substrate in a plasma processing cavity, vacuumizing, and introducing Ar with the volume ratio of 1:1₂And O₂The mixed gas is subjected to plasma glow discharge by applying 4KV high-voltage 80mA current by a microwave plasma discharge device, then is dried for 10min at the temperature of 120 ℃ to evaporate a solvent in a precursor solution to form a coating on a solute in the precursor solution, finally, the temperature is raised to the sintering temperatures of 500 ℃ and 600 ℃ and is respectively kept for 10min, the mixture is cooled to the room temperature along with a furnace, the sintering and cooling steps are repeated for a plurality of times, the last sintering is carried out, the temperature is respectively kept for 1h when the temperature is raised to 500 ℃ and 600 ℃ to ensure the sufficient oxidative decomposition of the precursor coating, and the coating load is 7g/m²IrO of (1)₂-Ta₂O₅And an electrode.

Example 2:

this example relates to the performance comparison of metal oxide coated electrodes prepared by a metal oxide coating electrode preparation process and a conventional thermal decomposition process.

Preparing a metal oxide coating electrode by adopting a traditional thermal decomposition method:

(1) TA pretreatment according to step (1) of example 1₂A substrate;

(2) according to implementationExample 1 step (2) preparation of precursor coating solution, the precursor solution is uniformly coated on the pretreated TA₂Drying the surface of the substrate for 10min at 120 ℃ to evaporate the solvent in the precursor coating liquid, annealing for 10min at 500 ℃ in the air atmosphere, repeating the drying and annealing steps for several times to obtain a set coating load, and preserving heat for 1h to ensure that the precursor coating liquid is fully oxidized and decomposed when the temperature is raised to 500 ℃ in the last sintering, so as to obtain a coating load of 7g/m²IrO of (1)₂-Ta₂O₅Electrode, and as a comparative example.

Performance comparison of metal oxide coated electrodes:

(1) the electrocatalytic activity is one of the main parameters for evaluating the electrocatalytic electrode performance, and the electric energy consumed by electrode reaction in an oxygen evolution environment is about 50-60%, so that the electrocatalytic activity of different metal oxide coating electrodes is generally compared by adopting the oxygen evolution current density under a certain potential;

respectively testing IrO prepared by traditional thermal decomposition method and plasma-assisted sintering method₂-Ta₂O₅Electrodes at 1M H₂SO₄The potentiodynamic polarization curve in the solution has the test potential of 1.0-1.4V and the potential scanning speed of 1.33mV/s, and the test result is shown in figure 1, which shows that IrO prepared by the plasma auxiliary sintering method₂-Ta₂O₅The oxygen evolution potential of the electrode is greatly reduced to about 1.15V, which is obviously lower than that of IrO prepared by the traditional thermal decomposition method₂-Ta₂O₅The oxygen evolution potential of the electrode (1.25V), a decrease in the oxygen evolution potential, indicates that in operation, IrO₂-Ta₂O₅The electrode can reach the oxygen evolution potential more quickly, and the efficiency and the electrode performance are improved;

IrO prepared by plasma-assisted sintering method₂-Ta₂O₅The current density of the electrode is larger than that of IrO prepared by the traditional thermal decomposition method₂-Ta₂O₅The current density of the electrode shows that the IrO prepared by the plasma-assisted sintering method₂-Ta₂O₅The electrocatalytic activity of the electrode is higher, the current efficiency is higher, and the practical application is realizedHigher gains are realized.

(2) The voltammetry area surrounded by cyclic voltammetry curves of the metal oxide coating electrode is in direct proportion to the charge capacity of the coating surface, the electrocatalytic activity of the electrode can be reflected, and the larger the area surrounded by the cyclic voltammetry curves is, the larger the voltammetry electric quantity Q of the electrode is, and the Q is in direct proportion to the active electric quantity of the electrode surface;

IrO prepared by traditional thermal decomposition method and plasma-assisted sintering method is respectively tested by cyclic voltammetry₂-Ta₂O₅Electrodes at 1M H₂SO₄The test results of cyclic voltammetry curve and voltammetry electric quantity in the solution are shown in fig. 2 and fig. 3, and the IrO prepared by the plasma-assisted sintering method is used for the area surrounded by the voltammetry curve₂-Ta₂O₅The electrode is larger than IrO prepared by the traditional thermal decomposition method₂-Ta₂O₅Electrode, description of IrO prepared by plasma-assisted sintering₂-Ta₂O₅The number of surface active points of the electrode is large, and the electrocatalytic activity is large; IrO prepared at 500 ℃ of sintering temperature of plasma-assisted sintering method for voltammetric capacity Q₂-Ta₂O₅Compared with IrO prepared by traditional thermal decomposition method, the electrode₂-Ta₂O₅The electrode is improved by 5 times, which shows that the IrO prepared by the plasma auxiliary sintering method₂-Ta₂O₅The electrocatalytic activity of the electrode is obviously increased.