A nanocrystal electrode with both electrocatalytic and photocatalytic activities

Abstract

The application discloses a nanocrystal electrode with electrocatalytic and photocatalytic activities. A preparation method comprises the following steps: firstly, polishing and soaking a titanium substrate in alkali and oxalic acid; preparing an intermediate layer by using a non-equilibrium flame gas aerosol method, setting specific radio frequency power, carrier gas and other parameters to form a high-entropy ceramic layer on the surface of the titanium plate; configuring a specific mixture as a starting material of a surface active layer by ball milling and other treatments, preparing the surface active layer by using a plasma directional explosion method, repeatedly adjusting parameters to improve the compactness; and finally, performing annealing treatment. The novel nanocrystal electrode has the characteristics of super-stable anti-chloride ion penetration ability, high mechanical strength, good electrical conductivity, stable uniformity and outstanding electrocatalytic and photocatalytic performance, and provides a new solution for the field of industrial waste water deep treatment.

Description

I. Technical Field

[0001] This invention relates to the field of environmental pollution control technology, specifically to a nanocrystalline electrode with both electrocatalytic and photocatalytic activities and its preparation method. II. Background Technology

[0002] Existing technologies in water pollution control include physical methods such as sedimentation and filtration, which can remove large particulate impurities but have limited effectiveness against dissolved pollutants; biological methods rely on microbial metabolism, have long treatment cycles, and are sensitive to toxic substances; and chemical methods such as flocculation and sedimentation are prone to secondary pollution. Electrochemical and photochemical technologies have significant advantages in water pollution control. Electrochemical technology can directly degrade pollutants through electrochemical reactions, is simple to operate, has a fast reaction speed, and can treat a variety of recalcitrant organic compounds. Photochemical technology uses light energy to generate strong oxidizing substances, has high efficiency in removing organic pollutants, and poses no risk of secondary pollution. Both technologies, in the advanced treatment of wastewater, can effectively remove low-concentration, recalcitrant pollutants, exhibiting high efficiency, energy saving, and environmental friendliness, providing a new and effective approach to water pollution control.

[0003] Photochemical water pollution control technology primarily utilizes light energy to excite chemical reactions to remove pollutants from water. Photocatalysis is one of the core methods. The basic principle is that a photocatalyst generates electron-hole pairs under light irradiation. Electrons react with dissolved oxygen in the water to generate strong oxidizing substances such as superoxide radicals, while holes react with water or hydroxide ions to generate hydroxyl radicals. These active species can oxidize and decompose organic pollutants, transforming them into harmless substances. The advantages of photocatalysis technology are: high efficiency and environmental friendliness, utilizing solar energy without secondary pollution; wide applicability, capable of degrading various organic pollutants; and mild reaction conditions, operating at room temperature and pressure. However, this technology also has some disadvantages. Regarding the catalytic activity of photocatalysts, current photocatalysts have limited utilization of sunlight and low quantum efficiency. In terms of stability, photocatalysts may experience photocorrosion and aggregation during long-term use, reducing their activity and stability. Regarding the efficiency of planar photocatalysts, due to the limited light-receiving area, the mass transfer efficiency is low, resulting in a relatively low overall treatment efficiency.

[0004] Electrochemical water pollution control technology utilizes electrochemical reactions to treat pollutants in water. The basic principle is to apply a voltage across an electrode, causing redox reactions in the pollutants on the electrode surface or in the solution, thereby removing or transforming the pollutants. Electrocatalysis is one of the important methods. Its advantages include: relatively fast reaction speed; controllable reaction process by adjusting parameters such as voltage and current; wide applicability, capable of treating various types of pollutants; and relatively simple equipment and convenient operation. However, it also has some disadvantages. Regarding the catalytic activity of electrocatalysts, current electrocatalysts still have room for improvement, and their effectiveness in treating some recalcitrant pollutants is limited. In terms of stability, electrocatalysts may be affected by corrosion and contamination during long-term operation, leading to a decrease in activity. Regarding electrocatalyst efficiency, the actual efficiency is lower than the theoretical value due to factors such as mass transfer limitations and side reactions on the electrode surface. Furthermore, the electrocatalytic process may consume a significant amount of electrical energy, resulting in high operating costs.

[0005] In the field of water pollution control, photocatalysis and electrocatalysis technologies have broad future development prospects. On the one hand, it is necessary to develop higher-performance photocatalysts and electrocatalysts to improve catalytic activity, stability, and efficiency. For photocatalysis, efforts should be made to improve the utilization rate of visible light and design novel nanostructured catalysts to increase specific surface area and active sites. For electrocatalysis, new electrode materials and structures should be explored to reduce overpotential and improve current efficiency. However, current research has limited mature technologies that organically combine photocatalysis and electrocatalysis. The photoelectrocatalysis technology, which is currently the subject of much laboratory research, is essentially a type of photocatalysis, utilizing the bias voltage provided by an electric field to enhance electron transfer in the photocatalytic process. Therefore, it cannot avoid some inherent limitations of photocatalysis, especially in the synergistic removal of multiple pollutants in complex water bodies, where the adaptability and reliability of the technology still need improvement. III. Summary of the Invention

[0006] This invention addresses the problems existing in the prior art. While photocatalysis and electrocatalysis play a role in the advanced treatment of wastewater, they suffer from numerous drawbacks. In photocatalysis, catalytic activity is limited by low solar energy utilization, especially in the visible light portion, resulting in low quantum efficiency; stability is poor, and photocorrosion and aggregation are common; planar photocatalysts have low efficiency, limited light-receiving area, and limited mass transfer efficiency. In electrocatalysis, catalytic activity is not ideal for treating recalcitrant pollutants; stability is easily reduced by corrosion and pollution; efficiency is limited by mass transfer and side reactions, resulting in low actual efficiency and high operating costs. Nanocrystalline electrodes, possessing both electrocatalytic and photocatalytic activity, offer significant advantages. They have a large specific surface area, abundant active sites, enhanced adsorption and degradation capabilities for pollutants, and higher stability. However, the preparation of nanocrystalline electrodes faces several technical obstacles. For example, precisely controlling the size and morphology of nanocrystals is extremely challenging; different parameters have complex effects on activity, making performance optimization difficult. Uniformity of nanocrystal loading on the electrode surface is difficult to guarantee, easily leading to localized activity differences. The preparation process is complex, requiring strict control of parameters such as temperature, atmosphere, and solution concentration, which not only increases the difficulty but also raises costs. Furthermore, the synthesis methods and growth mechanisms of nanocrystals require further in-depth research to achieve efficient and controllable preparation, providing more reliable technical support for the advanced treatment of wastewater.

[0007] Furthermore, when nanocrystalline electrodes are used as photoelectrocatalytic anode materials, chloride ion penetration from wastewater can easily lead to coating detachment, posing a stability risk. To address this issue, we discovered that a non-equilibrium flame aerosol method can be used to prepare multi-element composite coatings. Firstly, the combination of multiple elements produces a synergistic effect, enhancing the coating's stability and corrosion resistance. Tin improves the coating's conductivity and adhesion; zirconium provides oxidation stability; silicon helps form a dense structure, blocking chloride ion penetration; calcium fluoride enhances the coating's hardness and wear resistance; and gadolinium chloride may impart unique chemical stability to the coating. The formation of this high-entropy ceramic layer on a titanium substrate effectively prevents chloride ion penetration, improving the lifespan and stability of the nanocrystalline electrode under harsh environments.

[0008] Traditional electrodeposition methods for nanocrystalline electrodes suffer from numerous drawbacks, including low material utilization, severe secondary pollution, and uncontrolled nanocrystal growth leading to weak adhesion and easy peeling. We have discovered significant technical advantages in preparing the active layer using a multi-element mixture as the starting material and a plasma-directed explosion method. First, this method improves material utilization, reducing waste and secondary pollution. Second, plasma-directed explosion allows for precise control of nanocrystal growth, resulting in a more uniform and stable active layer structure. The addition of boron nitride enhances the mechanical strength and chemical stability of the active layer. The synergistic effects of metallic elements such as lead, titanium, manganese, and zinc endow the active layer with abundant catalytic active sites, improving the electrocatalytic performance of the electrode. Simultaneously, this preparation method strengthens the bond between the active layer and the intermediate layer, effectively preventing peeling and extending the electrode's lifespan.

[0009] To achieve the above objectives, the present invention provides a nanocrystalline electrode possessing both electrocatalytic and photocatalytic activities, characterized in that its preparation method includes the following steps:

[0010] Step 1: Select a titanium substrate with a purity of not less than 99.9%. First, use wire cutting to cut the titanium substrate. Use 200-400 grit coarse sandpaper to polish the titanium substrate until smooth. Then, use fine sandpaper of 800 grit or higher to polish and remove the oxide layer on the surface of the substrate. Soak the polished titanium substrate in a boiling 5% sodium hydroxide solution for 0.5 hours. After cleaning, soak it in a boiling solution containing 1% oxalic acid for 2 hours. Then soak it in a 0.1% oxalic acid solution for later use to prevent secondary oxidation of the titanium substrate.

[0011] Step 2: The intermediate layer of the nanocrystalline electrode is prepared by non-equilibrium flame aerosol method. The titanium plate pretreated in Step 1 is washed with deionized water and dried with nitrogen. It is then placed in the center of the non-equilibrium flame aerosol synthesis reactor. The non-equilibrium flame aerosol equipment is set with a radio frequency of 3 MHz, a power of 45 kW, argon as the carrier gas with a flow rate of 30 standard liters / min, and sheath gas as a mixture of equal volumes of argon and hydrogen with a flow rate of 120 standard liters / min.

[0012] Step 3: Prepare a mixture of metallic tin, zirconium nitrate, elemental silicon, calcium fluoride, and gadolinium chloride in a mass ratio of 17:3:2:1:0.02. The mixture is ball-milled to a particle size of less than 200 nanometers and thoroughly mixed. It is continuously fed through a vibrating powder feeder and transported by argon carrier gas to the injection nozzle of a non-equilibrium flame aerosol reactor for continuous and uniform spraying onto the surface of the titanium plate. The feed rate of the powder mixture is set to approximately 1.2–2.0 g / min. During the synthesis process, the reactor pressure is maintained at 66.7 kPa and the temperature is maintained at 1200 °C. After the reaction lasts for 200 seconds, a titanium substrate with a high-entropy ceramic layer that has ultra-stable resistance to chloride ion penetration is obtained.

[0013] Step 4: Prepare a mixture of boron nitride, lead, titanium, manganese and zinc in a mass ratio of 120:28:19:2:1 as the starting material for the surface active layer. Place the mixture in n-heptane and ball mill it for 40 hours under argon protection to obtain mixed nanoparticles with a particle size of less than 50 nanometers.

[0014] Step 5: The active layer on the surface of the nanocrystalline electrode is prepared by plasma directional explosion method. The titanium substrate with high-entropy ceramic layer obtained in step 3 is placed in the center of the discharge plasma sintering equipment. The mixed nanoparticles obtained in step 4 can be sputtered at high speed on the surface of the titanium substrate under argon gas. At the same time, a pulsed DC electric field with a voltage of 1.2 kV, a period of 100 ms, and a duty cycle of 5:1 is applied to both sides of the substrate. Since metals such as lead, titanium, manganese, and zinc are all active metals, they can undergo a sintering reaction during the sputtering process to form a surface active layer with high mechanical strength, good electrical conductivity, stability and uniformity, and similar expansion rate with the high-entropy ceramic layer on the surface of the titanium substrate. The reaction is stopped after 10 seconds.

[0015] Step 6: Perform a secondary plasma directional explosion step, adjust the pulsed DC voltage to 0.8 kV, the period to 10 milliseconds, and the duty cycle to 5:1 to improve the density of the surface active layer, and stop the reaction after 5 seconds.

[0016] Step 7: Repeat steps 5 and 6 in sequence again, repeating the operation 3 to 5 times to obtain a titanium substrate with a surface active layer with a multi-level stable structure.

[0017] Step 8, annealing treatment: Under a vacuum atmosphere of 0.1 to 1 Pa, the titanium substrate with the multi-level stable surface active layer obtained in step 7 is annealed at 350°C to further optimize the crystal structure and surface chemical state of the material, improve the electrocatalytic and photocatalytic performance of the electrode, and finally obtain a nanocrystalline electrode with both electrocatalytic and photocatalytic activities.

[0018] The advantages of this invention are:

[0019] 1) Improve material utilization and reduce pollution: Compared with the traditional electrodeposition method, the new method can improve material utilization, reduce waste and secondary pollution, and is more environmentally friendly.

[0020] 2) Precise control of nanocrystal growth: Plasma directional explosion method can precisely control nanocrystal growth, making the active layer structure uniform and stable, avoiding the problem of uncontrolled nanocrystal growth in traditional methods.

[0021] 3) Enhanced bonding and catalytic performance: Using a specific mixture as the starting material enhances the bonding between the active layer and the intermediate layer, preventing peeling and extending the electrode's lifespan. Simultaneously, multiple metal elements synergistically impart abundant catalytic active sites, improving electrocatalytic performance.

[0022] 4) Enhanced corrosion resistance and stability: The high-entropy ceramic layer prepared by the non-equilibrium flame aerosol method can effectively prevent chloride ion penetration, enhance the stability and corrosion resistance of the electrode in harsh environments, and provide reliable technical support for fields such as deep treatment of wastewater. IV. Description of the attached drawings

[0023] To more clearly illustrate the specific embodiments of the present invention, the accompanying drawings used in the following description of the specific embodiments are briefly explained. Figure 1 This is a schematic diagram of a non-equilibrium flame aerosol reactor. The reference numerals in the diagram are explained below:

[0024] 1-Vibrating powder feeder; 2-High-pressure argon gas cylinder; 3-RF controller; 4-Feeding pipeline; 5-Injection nozzle; 6-Sample tray; 7-Rotating base. Figure 2 The images show the characterization of the nanocrystalline electrode exhibiting both electrocatalytic and photocatalytic activities. Figure a is a scanning electron microscope (SEM) image of the nanocrystalline electrode prepared by the conventional electrodeposition method; Figure b is a SEM image of the nanocrystalline electrode prepared by the non-equilibrium flame aerosol and plasma directional explosion method; Figures c and d are X-ray diffraction patterns of the nanocrystalline electrode exhibiting both electrocatalytic and photocatalytic activities before and after a 1000-hour enhanced lifetime experiment.

[0025] Figure 3 The method described in this invention is used to treat landfill leachate, and to measure the change of the original concentration (calculated as chemical oxygen demand) over time under conditions of blank, electric, light, and photoelectric simultaneous presence.

[0026] Figure 4 The method described in this invention is used to analyze the changes in the concentration of the original fluid (calculated as chemical oxygen demand) over time under conditions of blank, electric, light, and photoelectric simultaneous presence. V. Detailed Implementation Methods

[0027] The present invention will now be described in detail with reference to the accompanying drawings and embodiments:

[0028] Example 1:

[0029] A nanocrystalline electrode with both electrocatalytic and photocatalytic activities is prepared by the following steps: First, a titanium substrate with a purity of not less than 99.9% is selected. The titanium substrate is then cut using wire cutting. It is polished smooth using 200-400 grit coarse sandpaper, followed by polishing with finer sandpaper (800 grit or higher) to remove the oxide layer from the substrate surface. The polished titanium substrate is then immersed in a boiling 5% sodium hydroxide solution for 0.5 hours, cleaned, and then immersed in a boiling solution containing 1% oxalic acid for 2 hours. Finally, it is immersed in a 0.1% oxalic acid solution for later use to prevent secondary oxidation of the Ti substrate. The intermediate layer of the nanocrystalline electrode is prepared using a non-equilibrium flame aerosol method. The pretreated titanium plate is then subjected to… After rinsing with deionized water and drying with nitrogen, the material is placed in the center of a non-equilibrium flame aerosol synthesis reactor. The non-equilibrium flame aerosol equipment is set to 3 MHz radio frequency, 45 kW power, with argon as the carrier gas at a flow rate of 30 standard liters / minute, and a sheath gas consisting of an equal volume mixture of argon and hydrogen at a flow rate of 120 standard liters / minute. A mixture of metallic tin, zirconium nitrate, elemental silicon, calcium fluoride, and gadolinium chloride in a mass ratio of 17:3:2:1:0.02 is prepared, ball-milled to a particle size of less than 200 nanometers, and thoroughly mixed. The mixture is continuously fed through a vibrating powder feeder and transported via argon carrier gas to the injection nozzle of the non-equilibrium flame aerosol reactor, where it is continuously and uniformly sprayed onto the surface of the titanium plate (a simplified structural diagram of the non-equilibrium flame aerosol reactor is attached). Figure 1As shown), the feed rate of the powder mixture was set to approximately 1.2–2.0 g / min. During the synthesis process, the reactor pressure was maintained at 66.7 kPa and the temperature at 1200 °C. After the reaction lasted for 200 seconds, a titanium substrate with a high-entropy ceramic layer exhibiting ultra-stable resistance to chloride ion penetration was obtained. A mixture of boron nitride, lead, titanium, manganese, and zinc in a mass ratio of 120:28:19:2:1 was used as the starting material for the surface active layer. This mixture was placed in n-heptane and ball-milled for 40 hours under argon protection to obtain mixed nanoparticles with a particle size of less than 50 nanometers. The nanocrystalline electrode surface active layer was prepared using a plasma-directed explosion method. The titanium substrate with the high-entropy ceramic layer obtained in step 3 was placed in the center of a spark plasma sintering device. The mixed nanoparticles obtained in step 4 were sputtered onto the surface of the titanium substrate at high speed under argon delivery. Simultaneously, a voltage of 1.2 kV with a period of 100 milliseconds and a duty cycle of [missing information] were applied to both sides of the substrate. A 5:1 pulsed DC electric field is applied. Since lead, titanium, manganese, and zinc are all reactive metals, they can undergo a sintering reaction during sputtering, forming a surface-active layer with high mechanical strength, good electrical conductivity, stability, uniformity, and similar expansion rates with the high-entropy ceramic layer on the titanium substrate surface. The reaction is stopped after 10 seconds. A second plasma-directed explosion step is performed, adjusting the pulsed DC voltage to 0.8 kV, the period to 10 milliseconds, and the duty cycle to 5:1 to improve the density of the surface-active layer. The reaction is stopped after 5 seconds. This process is repeated 3 to 5 times to obtain a titanium substrate with a multi-level stable surface-active layer. Annealing is then performed at 350°C under a vacuum atmosphere of 0.1 to 1 Pa to further optimize the crystal structure and surface chemical state of the material, improve the electrocatalytic and photocatalytic performance of the electrode, and finally obtain a nanocrystalline electrode with both electrocatalytic and photocatalytic activities.

[0030] The scanning electron microscope image of the obtained nanocrystalline electrode is attached. Figure 2 As shown in b. The nanocrystalline electrode surface structure prepared by this method is more dense, while in contrast, the nanocrystalline electrode structure prepared by the traditional electrodeposition method (see attached diagram) is much denser. Figure 2 a) It is relatively rough with many cracks on the surface, which can easily lead to structural instability and coating peeling.

[0031] Example 2:

[0032] Accelerated lifetime testing was performed on the nanocrystalline electrode obtained in Example 1, which exhibits both electrocatalytic and photocatalytic activities, to examine its resistance to chloride ion penetration. Accelerated lifetime testing conditions: 1M hydrochloric acid, 60°C, current density 1 A cm⁻¹. -2 The electrode spacing is 10mm, and the accelerated life test cycle is 1000 hours.

[0033] The results are attached. Figure 2As shown in c and d, after 1000 hours of enhanced life test, the crystal structure of the electrode surface did not change significantly, proving that it has a strong ability to resist chloride ion penetration, and no obvious coating peeling was observed.

[0034] Example 3:

[0035] The nanocrystalline electrode with both electrocatalytic and photocatalytic activities prepared in this invention was used to treat landfill leachate collected from a landfill. The initial concentration (chemical oxygen demand) of the landfill leachate was 350 mg / L, the ammonia nitrogen concentration was 120 mg / L, and the chloride ion concentration was 12000 mg / L. The wastewater was treated under the simultaneous presence of light, electricity, and photoelectricity.

[0036] The reactor is made of plexiglass and has dimensions of 30 (length) × 30 (width) × 50 (height) cm. 3 The working electrode is a nanocrystalline electrode with both electrocatalytic and photocatalytic activities prepared by the method described in this invention, with an area of ​​30 (length) × 30 (width) cm. 2， The counter electrode, made of stainless steel of the same size as the working electrode, is placed on one side of the reactor, while the counter electrode is placed on the other side. A 500W short-arc medium-pressure mercury lamp is used as the light source for the photochemical reaction, with an external quartz waterproof cover placed in the middle of the reactor. The electrochemical reaction is powered by a DC regulated power supply providing a constant current source with a current density of 10 mA / cm². -2 The magnetic stirring speed was 1000 rpm. Samples were taken periodically, and the chemical oxygen demand (COD) concentration in the water samples was determined according to HJ828-2017 (Water Quality - Determination of Chemical Oxygen Demand - Potassium Dichromate Method). Tests were conducted using three methods: light on, power off for a simple photochemical performance test; light off, power on for a simple electrochemical test; and light on, power on for a photoelectric synchronous test.

[0037] The reaction results are attached. Figure 3 As shown, in the blank experiment, no degradation occurred in the landfill leachate. Under light-only conditions, the removal efficiency of pollutants was low, with the chemical oxygen demand (COD) concentration decreasing by only 56.8% after 60 minutes of treatment. Under constant current power supply only, the COD concentration decreased by 69.3% after 60 minutes of treatment. When both light and electricity were present, the COD concentration decreased by 89.2% after 60 minutes of treatment.

[0038] Example 4:

[0039] The nanocrystalline electrode with both electrocatalytic and photocatalytic activities prepared in this invention was used to treat fracturing flowback fluid collected from a shale gas operation site. The initial concentration (chemical oxygen demand) of the fracturing flowback fluid was 120 mg / L, the ammonia nitrogen concentration was 0.17 mg / L, and the chloride ion concentration was 8600 mg / L. The wastewater was treated under the simultaneous presence of light, electricity, and photoelectricity.

[0040] The specific operating procedure is the same as in Example 3 and will not be repeated here. The reaction results are attached. Figure 4 As shown, in the blank experiment, no degradation occurred in the fracturing flowback fluid. Under light-only conditions, the removal efficiency of pollutants was low. After 10 minutes of treatment, the chemical oxygen demand (COD) concentration decreased by 80%. Under constant current power supply only, the COD concentration decreased by 85.4% after 10 minutes of treatment. When both light and electricity were present, the COD concentration decreased by 95.2% after 10 minutes of treatment. After 60 minutes of treatment, almost complete degradation was achieved.

[0041] The specific embodiments described above are only used to illustrate the spirit of the present invention. The scope of protection of the present invention is not limited thereto. For those skilled in the art, other embodiments can be easily made by means of changes, substitutions or modifications based on the technical content disclosed in this specification. All such other embodiments should be covered within the scope of protection of the present invention.

Claims

1. A nanocrystalline electrode having both electrocatalytic and photocatalytic activity, characterized in that, The preparation method comprises the following steps: Step 1, a titanium substrate with a purity of not less than 99.9% is selected, the titanium substrate is first cut by using a wire cutting, the titanium substrate is polished to be smooth by using 200-400 mesh coarse sandpaper, then fine sandpaper with a mesh number of more than 800 is selected to polish and remove the surface oxidation layer of the substrate, the polished titanium substrate is soaked in a boiling sodium hydroxide solution with a mass concentration of 5% for 0.5 hours, after washing, the titanium substrate is soaked in a boiling oxalic acid solution with a mass concentration of 1% for 2 hours, and then is soaked in an oxalic acid solution with a mass concentration of 0.1% for standby, so as to prevent the titanium substrate from being oxidized again; Step 2, the mesocrystal electrode intermediate layer is prepared by using a non-equilibrium flame gas sol method, the pretreated titanium substrate in step 1 is washed by deionized water and dried by nitrogen, is placed in the center of a non-equilibrium flame gas sol synthesis reactor, the radio frequency of the non-equilibrium flame gas sol equipment is set to 3 MHz, the power is 45 kW, argon is used as the carrier gas, the flow rate is 30 standard liters / minute, the sheath gas is an argon and hydrogen mixed gas with an equal volume, and the flow rate is 120 standard liters / minute; Step 3, a mixture of metal tin, zirconium nitrate, elemental silicon, calcium fluoride and gadolinium chloride with a mass ratio of 17:3:2:1:0.02 is prepared, is broken by ball milling to a particle size of less than 200 nanometers and is fully mixed, is continuously fed by a vibrating powder feeder, and is continuously and uniformly sprayed onto the surface of the titanium plate by being conveyed to the injection nozzle of the non-equilibrium flame gas sol reactor by argon carrier gas, the feeding rate of the powder mixture is set to 1.2-2.0 grams / minute, in the synthesis process, the pressure of the reactor is kept at 66.7 kPa, and the temperature is kept at 1200°C, after the reaction lasts for 200 seconds, a titanium substrate with a high-entropy ceramic layer with super-stable anti-chloride ion immersion ability is obtained; Step 4, a mixture of boron nitride, metal lead, metal titanium, metal manganese and metal zinc with a mass ratio of 120:28:19:2:1 is configured as the starting material of the surface active layer, the mixture is placed in n-heptane, and under the protection of argon, the mixture is ball milled for 40 hours to obtain mixed nanoparticles with a particle size of less than 50 nanometers; Step 5, the surface active layer of the mesocrystal electrode is prepared by using a plasma directional explosion method, the titanium substrate with the high-entropy ceramic layer obtained in step 3 is placed in the center of a discharge plasma sintering device, the mixed nanoparticles obtained in step 4 are sputtered on the surface of the titanium substrate at a high speed under the conveying of argon, at the same time, a pulse direct current electric field with a voltage of 1.2 kV, a period of 100 milliseconds and a duty cycle of 5:1 is applied to both sides of the substrate, since the metal lead, the metal titanium, the metal manganese and the metal zinc are all active metals, sintering reactions occur in the sputtering process, and a surface active layer with high mechanical strength, good electrical conductivity, stable uniformity and similar expansion rate is formed with the high-entropy ceramic layer on the surface of the titanium substrate, the reaction lasts for 10 seconds and then stops; Step 6, a secondary plasma directional explosion step is carried out, the pulse direct current voltage is adjusted to 0.8 kV, the period is adjusted to 10 milliseconds, and the duty cycle is adjusted to 5:1, so as to improve the compactness of the surface active layer, the reaction lasts for 5 seconds and then stops; Step 7, steps 5 and 6 are repeatedly performed again in sequence, the repeated operation is performed 3-5 times, and a titanium substrate with a surface active layer with a multi-level stable structure is obtained. Step 8, annealing treatment, the titanium substrate with the surface active layer of multi-stage stable structure obtained in step 7 is annealed at 350°C under a vacuum atmosphere of 0.1-1 Pa to further optimize the crystal structure and surface chemical state of the material, and improve the electrocatalytic and photocatalytic performance of the electrode, so as to finally obtain a nanocrystalline electrode with electrocatalytic and photocatalytic activity.

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