A Ti / Ag / alpha-PbO2 / beta-PbO2 electrode, a preparation method and application thereof

Abstract

The application provides a Ti / Ag / alpha-PbO2 / beta-PbO2 electrode and a preparation method and application thereof, and relates to the technical field of electrochemistry.The titanium base is subjected to mixed acid etching treatment, so that a titanium base with moderate surface roughness and uniform distribution is obtained, so as to increase the contact area with the silver single layer; then, silver mirror reaction is used to plate Ag, and the titanium base plated with Ag is further subjected to high-temperature sintering treatment, so that the bonding force between the titanium base and the Ag layer is increased; after heat treatment, the Ag layer still maintains the morphology with moderate surface roughness, and the surface area is large, which is beneficial to the rapid electrodeposition of the alpha-PbO2 layer, so that the beta-PbO2 layer is combined with the titanium base more firmly; and the irregular crack structure specific to the intermediate layer prepared by the thermal decomposition method is avoided.The principle of the electrode preparation process design is scientific and reliable, the preparation process is simple, complex equipment is not needed, the electrocatalytic oxidation performance of the electrode is excellent, and the preparation difficulty of the complex titanium-based coating electrode is greatly reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of electrochemistry, in particular to a Ti / Ag / α-PbO2 / β-PbO2 electrode and a preparation method and application thereof. BACKGROUND

[0002] Electrochemical catalytic oxidation technology is an important branch of electrochemistry, and is a kind of advanced oxidation technology that can effectively control environmental pollution. It has excellent characteristics such as simple operation, high efficiency, no pollution and sustainability, and has been widely concerned. It has been applied to the treatment of various wastewater such as dye wastewater and papermaking wastewater. Electrode material is a key component of electrochemistry. PbO2 electrode with titanium as matrix material has the advantages of low cost and high oxygen evolution potential, and is widely used in the field of electrochemistry. The active radicals such as ·OH generated on the surface of PbO2 active layer can directly react with organic pollutants, so that the organic pollutants are finally decomposed into H2O and CO2. However, Ti / PbO2 electrode also has problems such as brittleness, easy deactivation, large internal stress at the electrode interface, easy peeling of the coating, short service life and the like in practical application, which greatly limits its practical application. In addition, when Ti / PbO2 electrode is used for electrocatalytic oxidation of organic pollutants for a long time, the electrolyte solution will erode and dissolve the PbO2 active layer on the surface of the electrode, and finally the titanium matrix surface will be oxidized to TiO2 with weak conductivity, thereby accelerating the peeling of the PbO2 active layer, reducing the service life of the electrode, and reducing the electrocatalytic activity of the electrode, which also greatly limits the practical application of Ti / PbO2 electrode.

[0003] Adding a suitable intermediate layer can not only reduce the internal stress between the coatings, but also improve the corrosion resistance, chemical stability and service life of the electrode. The common tin-antimony oxide intermediate layer and α-PbO2 intermediate layer can improve the service life of the electrode, but there are still problems such as insufficient electrocatalytic ability in practical application. In addition, the metal oxide intermediate layer prepared by thermal decomposition method has irregular crack structure generated by alternating high temperature and room temperature, which is not conducive to the chemical stability and service life of Ti / PbO2 electrode. The introduction of Ag as an intermediate layer into the titanium-based coating electrode can improve the electrocatalytic activity of the electrode, but when PbO2 / β-PbO2 is directly electrodeposited on the surface of Ti / Ag electrode, the Ag layer on the surface of Ti / Ag electrode will dissolve and generate a large amount of bubbles (O2), which will eventually lead to problems such as uneven and non-dense coating. Θ Ag+ / Ag Θ O2 / H2O Θ PbO2 / Pb 2+ When PbO2 / β-PbO2 is directly electrodeposited on the surface of Ti / Ag electrode, the Ag layer on the surface of Ti / Ag electrode will dissolve and generate a large amount of bubbles (O2), which will eventually lead to problems such as uneven and non-dense coating. SUMMARY

[0004] ​​The application provides a Ti / Ag / alpha-PbO2 / beta-PbO2 electrode and a preparation method and application thereof, and aims to solve the problems in the background art.

[0005] To achieve the above-mentioned purpose, the application provides a Ti / Ag / alpha-PbO2 / beta-PbO2 electrode and a preparation method and application thereof. The application has a simple manufacturing process. The dense alpha-PbO2 layer can protect the Ag layer and effectively relieve active oxygen penetration, greatly prolonging the service life of the electrode. The beta-PbO2 has a dense quadrangular pyramid structure, which can effectively prevent active oxygen from penetrating the electrode surface, protect the outer layer of the electrode from falling off, improve the electrode performance, prolong the service life of the electrode, and provide abundant active sites for efficient electrocatalytic degradation of organic pollutants.

[0006] The application provides a preparation method of the Ti / Ag / alpha-PbO2 / beta-PbO2 electrode, which comprises the following steps.

[0007] S1: preparing a mixed acid solution and heating, and then placing the titanium substrate subjected to ultrasonic treatment to etch, to obtain a pretreated titanium substrate;

[0008] S2: preparing a silver plating solution, placing the pretreated titanium substrate in the silver plating solution to plate silver, taking out the titanium substrate after the silver plating is completed, cleaning the titanium substrate with ultrapure water, and naturally airing or drying; replacing the silver plating solution and repeating the silver plating several times; and subjecting to high-temperature heat treatment to obtain a Ti / Ag electrode; wherein the silver layer is uniformly and densely attached to the surface of the titanium substrate and the silver layer maintains a morphology with moderate roughness. It should be noted that the silver layer prepared by the classical silver mirror reaction plating combined with high-temperature heat treatment has a structure with moderate roughness and a large specific surface area, which is beneficial to rapid electrodeposition of alpha-PbO2; in addition, the silver layer can react with active oxygen penetrating the alpha-PbO2 during the use of the electrode to generate Ag2O with conductivity, effectively relieving the problem that the titanium substrate surface generates weakly conductive TiO2 to cause the plating layer to easily fall off and the like;

[0009] S3: preparing an alpha-PbO2 electroplating solution and performing electrodeposition of the Ti / Ag electrode in the alpha-PbO2 electroplating solution, and cleaning with deionized water to obtain a Ti / Ag / alpha-PbO2 electrode;

[0010] S4: preparing a beta-PbO2 electroplating solution and performing electrodeposition of the Ti / Ag / alpha-PbO2 electrode in the beta-PbO2 electroplating solution, and cleaning with deionized water to obtain a Ti / Ag / alpha-PbO2 / beta-PbO2 electrode.

[0011] According to one aspect of the application, in step S1, the thickness of the titanium substrate is any one of 0.1 mm, 0.2 mm and 0.3 mm; and the mixed acid solution comprises sulfuric acid and tartaric acid.

[0012] According to one aspect of the present application, in step S2, the silver plating solution comprises silver salt, dilute ammonia, strong base and reducing aldehyde.

[0013] According to one aspect of the present application, the silver salt is silver nitrate, the concentration of which is 2.0-6.0wt.%; the strong base is any one of sodium hydroxide and potassium hydroxide, the concentration of which is 1.0-4.0wt.%; the reducing aldehyde is any one of glucose, formaldehyde and acetaldehyde, the concentration of which is 3.0-7.0wt.%; the concentration of the dilute ammonia is 2.0-10.0wt.%.

[0014] According to one aspect of the present application, in step S2, the silver plating time is 20-80min; the silver plating frequency is 1-5 times; the drying temperature is 30-50℃; and the heat treatment temperature is 350-500℃.

[0015] According to one aspect of the present application, in step S3, the electrodeposition process is as follows: at 30-60℃, 2-7mA / cm 2 electrodeposition for 2-5h.

[0016] According to one aspect of the present application, in step S4, the electrodeposition process is as follows: first, at 40-70℃, 10mA / cm 2 electrodeposition for 10-30min; then, increase the current density by 5mA / cm 2 electrodeposition for 5min, and the total electrodeposition time is 30-60min.

[0017] Based on the general concept of the present application, the embodiments of the present application provide the Ti / Ag / α-PbO2 / β-PbO2 electrode obtained by the above-mentioned preparation method.

[0018] The embodiments of the present application also provide the application of the Ti / Ag / α-PbO2 / β-PbO2 electrode obtained by the above-mentioned preparation method in electrochemical degradation of anthraquinone organic dye wastewater.

[0019] According to one aspect of the present application, the anthraquinone organic dye is alizarin red S.

[0020] Reaction mechanism:

[0021] The present application selects the best conductive metal Ag element as the intermediate layer, and through the classic silver mirror reaction to plate the Ag layer, so that the Ag layer is uniformly and completely attached to the titanium substrate with moderate surface roughness and uniform distribution. Further high temperature heat treatment of the plated Ag layer improves the bonding force of the titanium substrate and the Ag layer, and the plated Ag layer after heat treatment still maintains the basic morphology of moderate surface roughness, increases the coating coverage area; the Ag layer as the intermediate layer not only has high conductivity, but also can react with active oxygen penetrating the surface of the active layer, and can also generate conductive Ag2O, effectively preventing the diffusion of active oxygen molecules or active oxygen atoms to the surface of the titanium substrate, avoiding the generation of weakly conductive TiO2 on the surface of the titanium substrate, causing the plated layer to fall off, thereby improving the stability of the electrode. Selecting Ag element as the intermediate layer can significantly increase the bonding force between the titanium substrate and the PbO2 layer, increase the conductivity of the electrode, reduce the electrode resistance, improve the electrode stability, and enhance the service life of the electrode, which has great application potential in the field of electrochemical technology. And in alkaline conditions, when the alpha-PbO2 layer is deposited on the surface of the Ti / Ag electrode and then the beta-PbO2 layer is deposited, the problem of Ag dissolution on the surface of the Ti / Ag electrode to produce a large amount of bubbles (O2) and thus cause the plated layer to be uneven and not dense can be effectively avoided.

[0022] The above-mentioned scheme of the present application has the following beneficial effects:

[0023] (1) The present application performs mixed acid etching treatment on the titanium substrate to obtain a titanium substrate with moderate surface roughness and uniform distribution, increasing the contact area with the silver element layer; then the classic silver mirror reaction is used to plate Ag, effectively avoiding the CN - pollution, difficult treatment of electroplating waste liquid, unpredictable harm to the environment and a series of problems. Further high temperature sintering treatment of the titanium substrate after Ag plating increases the bonding force between the titanium substrate and the Ag layer. After heat treatment, the Ag layer still maintains the morphology of moderate surface roughness, and has a large surface area, which is beneficial to the rapid electrodeposition of the alpha-PbO2 layer, making the beta-PbO2 layer more firmly combined with the titanium substrate; and avoids the irregular cracking structure unique to the intermediate layer prepared by thermal decomposition method.

[0024] (2) The present application first deposits an alpha-PbO2 layer on the surface of the Ti / Ag electrode under alkaline conditions, and then deposits a beta-PbO2 layer, effectively avoiding the key problem that the Ag layer is dissolved when directly electrodeposits PbO2 / beta-PbO2 layer on the surface of the Ti / Ag electrode, successfully introducing high-conductivity Ag into the titanium-based coating electrode, significantly increasing the bonding force between the titanium substrate and the beta-PbO2 active layer, improving the conductivity of the electrode, improving the stability of the electrode, and enhancing the service life of the electrode.

[0025] (3) The preparation process of the Ti / Ag / α-PbO2 / β-PbO2 electrode is designed based on scientific and reliable principles, has simple preparation process, does not need complex equipment, has excellent electro-catalytic oxidation performance of the electrode, and greatly reduces the preparation difficulty of the complex titanium-based coating electrode. BRIEF DESCRIPTION OF DRAWINGS

[0026] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0027] Figure 1 The electrode prepared for the embodiment 1 and the comparative example 1 of the present application is an electrode prepared for the embodiment 1 and the comparative example 1 of the present application.

[0028] Figure 2 The electrode prepared for the embodiment 1 and the comparative example 1 of the present application is an electrode prepared for the embodiment 1 and the comparative example 1 of the present application.

[0029] Figure 3 The SEM image of the Ti / Ag electrode after silver plating and heat treatment in the embodiment 1 of the present application is an SEM image of the Ti / Ag electrode after silver plating and heat treatment in the embodiment 1 of the present application.

[0030] Figure 4 The EDS image of the Ti / Ag electrode after silver plating and heat treatment in the embodiment 1 of the present application is an EDS image of the Ti / Ag electrode after silver plating and heat treatment in the embodiment 1 of the present application.

[0031] Figure 5 The SEM image of the Ti / Ag / α-PbO2 electrode prepared in the embodiment 1 of the present application is an SEM image of the Ti / Ag / α-PbO2 electrode prepared in the embodiment 1 of the present application.

[0032] Figure 6 The EDS image of the Ti / Ag / α-PbO2 electrode prepared in the embodiment 1 of the present application is an EDS image of the Ti / Ag / α-PbO2 electrode prepared in the embodiment 1 of the present application.

[0033] Figure 7 The EDS image of the Ti / Ag / α-PbO2 electrode prepared in the embodiment 1 of the present application after the α-PbO2 layer is scraped off is an EDS image of the Ti / Ag / α-PbO2 electrode prepared in the embodiment 1 of the present application after the α-PbO2 layer is scraped off.

[0034] Figure 8 The SEM image of the Ti / Ag / α-PbO2 / β-PbO2 electrode prepared in the embodiment 1 of the present application is an SEM image of the Ti / Ag / α-PbO2 / β-PbO2 electrode prepared in the embodiment 1 of the present application.

[0035] Figure 9 The XRD image of the Ti / Ag / α-PbO2 electrode and the Ti / Ag / α-PbO2 / β-PbO2 electrode prepared in the embodiment 1 of the present application is an XRD image of the Ti / Ag / α-PbO2 electrode and the Ti / Ag / α-PbO2 / β-PbO2 electrode prepared in the embodiment 1 of the present application.

[0036] Figure 10 The degradation rate of alizarin red S of the electrode prepared in the embodiment and the comparative example of the present application is a degradation rate of alizarin red S of the electrode prepared in the embodiment and the comparative example of the present application. DETAILED DESCRIPTION

[0037] In order to make the technical problems, technical solutions and advantages to be solved by the present application more clear, the following will be described in detail in combination with the drawings and specific embodiments.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the protection scope of the present application.

[0039] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present application can be purchased from the market or can be prepared by existing methods.

[0040] In view of the problems of insufficient electrocatalytic ability of the existing tin-antimony oxide intermediate layer and alpha-PbO2 intermediate layer in practical application, such as the irregular crack structure generated by the alternating change of high temperature and room temperature of the metal oxide intermediate layer prepared by thermal decomposition method, which is not conducive to the chemical stability and service life of the Ti / PbO2 electrode. The Ag is introduced as an intermediate layer into the titanium-based coated electrode. When in acidic conditions, due to E Θ Ag+ / Ag = 0.7996 is less than E Θ O2 / H2O = 1.229, E Θ PbO2 / Pb 2+ = 1.455, when PbO2 / β-PbO2 is directly electrodeposited on the surface of the Ti / Ag electrode, the Ag layer on the surface of the Ti / Ag electrode will dissolve and a large amount of bubbles (O2) will be generated, which will eventually lead to problems such as uneven and non-dense plating.

[0041] The embodiment of the present application provides a Ti / Ag / alpha-PbO2 / beta-PbO2 electrode and a preparation method and application thereof.

[0042] The following will be described through specific examples and comparative examples.

[0043] Example 1

[0044] The preparation method of the Ti / Ag / alpha-PbO2 / beta-PbO2 electrode related in the present embodiment, the specific process includes three steps of mixed acid etching of titanium substrate, preparation of Ag layer and electrodeposition of PbO2 layer:

[0045] (1) Mixed acid etching of titanium substrate

[0046] Firstly, the titanium substrate is cut into 2cm*4cm*0.2mm, put into acetone for ultrasonic cleaning for 40min, then taken out with tweezers and dried for standby;

[0047] Then, 100 mL of 20% sulfuric acid and 15% tartaric acid solution were prepared respectively, sealed and stored, and the sulfuric acid and tartaric acid solution were mixed in a volume ratio of 2:1 to prepare mixed acid;

[0048] Finally, the mixed acid solution was heated to 100°C, and etched in the titanium matrix. The etching time was 60 min, and the titanium matrix was turned over every 20 min. After etching, the titanium matrix was taken out with tweezers and washed several times with deionized water, placed on filter paper, dried at room temperature, and sealed for storage.

[0049] (2) Preparation of Ag layer

[0050] First, 50 mL of 4.0 wt.% AgNO3 solution, 8.0 wt.% dilute ammonia water, 2.0 wt.% NaOH solution and 5.0 wt.% glucose solution were prepared respectively, and stored at room temperature.

[0051] Then, 8 mL of AgNO3 (4.0 wt.%) solution was added to a beaker (25 mL), and 8.0 wt.% dilute ammonia water (about 5 mL) was added dropwise to make the solution just dissolve, and the solution became clear and transparent. Then the same volume of dilute ammonia water was added dropwise, and 8 mL of 5 wt.% NaOH solution was added (the solution did not turn black). Under the condition of 500 rpm stirring, 12 mL of 5 wt.% glucose solution was added, and after 5 s of continuous high-speed stirring, the stirring was stopped. Four pieces of titanium matrix (2 cm x 4 cm x 0.2 mm) were clamped and hung with a paper clip, and were placed vertically in the above solution. After 40 min of silver mirror reaction, the silver-plated titanium matrix was taken out, washed several times with ultrapure water, and dried in an oven at 30-50°C or naturally air-dried to obtain Ti / Ag electrode. The silver-plating liquid was replaced, and the silver-plating was repeated three times, and the electrode was dried.

[0052] After the last silver plating, it was placed in a vacuum tube furnace and heat treated at 400°C for 60 min, and naturally annealed for more than 5 h. The titanium matrix was taken out to obtain Ti / Ag electrode with strong bonding force between Ti matrix and Ag layer.

[0053] (3) Electrodeposition of PbO2 layer includes first electrodeposition of α-PbO2 layer, and then electrodeposition of β-PbO2 layer.

[0054] First, 50 mL of α-PbO2 plating solution containing 0.1 mol / L PbO and 3.5 mol / L NaOH was prepared, and 50 mL of β-PbO2 plating solution containing 0.5 mol / L Pb(NO3)2, 0.04 mol / L NaF and 0.1 mol / L HNO3 was prepared;

[0055] Then, the Ti / Ag electrode (1 cm x 1 cm x 0.2 mm) after high-temperature heat treatment was used as an anode, and a platinum plate electrode with the same size was used as a cathode, and a low current density was used to electrodeposit an α-PbO2 layer in an electroplating solution at 40 ℃ for 4 h 2 The electrode was taken out and washed with deionized water to obtain a Ti / Ag / α-PbO2 electrode.

[0056] Finally, a β-PbO2 active layer was prepared by a step-by-step electrodeposition method, the Ti / Ag / α-PbO2 electrode was used as an anode, and a platinum plate electrode with the same size was used as a cathode, and a low current density was used to electrodeposit a β-PbO2 layer in an electroplating solution at 60 ℃, first at a current density of 10 mA / cm 2 for 20 min, and then at current densities of 15, 20, 25, 30, 35, 40, 45 and 50 mA / cm 2 for 5 min, respectively; the electrode was taken out and washed with deionized water to obtain a Ti / Ag / α-PbO2 / β-PbO2 electrode.

[0057] In the preparation process of the Ag intermediate layer, the classical silver mirror reaction was used to plate Ag, which effectively avoided a series of problems such as CN - contamination in the process of electrodepositing Ag, difficult treatment of electroplating waste liquid, and unpredictable harm to the environment; further, high-temperature sintering heat treatment was used to plate Ag on the titanium substrate, which increased the bonding force between the titanium substrate and the Ag layer; in addition, the Ti / Ag electrode after heat treatment still maintained a surface roughness morphology with a large surface area. On the one hand, the Ag layer structure is conducive to the rapid electrodeposition of a dense α-PbO2 layer to protect the Ti / Ag electrode; on the other hand, it makes the α-PbO2 more firmly combined with the titanium substrate and rapidly electrodeposits and generates a β-PbO2 with a dense four-pyramid structure. As a highly conductive metal, Ag can also react with active oxygen penetrating the surface of the active layer to generate conductive Ag2O, which effectively prevents the diffusion of oxygen molecules or oxygen atoms to the surface of the titanium substrate, greatly alleviates the generation of weakly conductive TiO2 on the surface of the titanium substrate, avoids the peeling of the plating layer, and further improves the stability of the electrode. In an alkaline condition, the use of a low current density to first deposit an α-PbO2 layer on the surface of the Ti / Ag electrode can effectively avoid the dissolution of Ag on the surface of the Ti / Ag electrode to generate a large amount of bubbles (O2), thereby causing problems such as uneven and non-dense plating. The selection of the Ag layer as the intermediate layer of the Ti / PbO2 electrode can significantly increase the bonding force between the titanium substrate and the PbO2 layer, increase the conductivity of the electrode, reduce the electrode resistance, improve the stability of the electrode, and enhance the service life of the electrode. In addition, the β-PbO2 prepared by the present application has a dense four-pyramid structure, which can effectively prevent the diffusion of oxygen molecules or oxygen atoms to the surface of the titanium substrate and increase the surface area and electrocatalytic oxidation active sites of the active layer, and has great application potential in the field of electrochemical technology.

[0058] Comparative Example 1

[0059] The preparation process of a Ti / β-PbO2 electrode involved in the present comparative example includes two steps of mixed acid etching of titanium substrate and electrodeposition of β-PbO2 layer:

[0060] (1) Mixed acid etching of titanium substrate

[0061] Firstly, the titanium substrate was cut into 2 cm x 4 cm x 0.2 mm, ultrasonically cleaned in acetone for 40 min, then taken out with tweezers and dried for standby;

[0062] Then, 100 mL of 20% sulfuric acid and 15% tartaric acid solutions were respectively prepared, sealed for standby, and the sulfuric acid and tartaric acid solutions were mixed in a volume ratio of 2:1 to prepare a mixed acid;

[0063] Finally, the mixed acid solution was heated to 100°C and put into the titanium substrate for etching, the etching time was 60 min, after etching, the titanium substrate was taken out with tweezers and washed several times with deionized water, placed on filter paper, dried at room temperature, and sealed for storage.

[0064] (2) Electrodeposition of β-PbO2 layer

[0065] Firstly, 100 mL of β-PbO2 plating solution containing 0.5 mol / L Pb(NO3)2, 0.04 mol / L NaF and 0.1 mol / L HNO3 was prepared;

[0066] Then, a β-PbO2 active layer was prepared by stepwise electrodeposition method, taking the titanium substrate (1 cm x 1 cm) as an anode and a platinum electrode of the same size as a cathode, in the plating solution at 60°C, first electrodeposition for 20 min at a current density of 10 mA / cm 2 , then electrodeposition for 5 min at current densities of 15, 20, 25, 30, 35, 40, 45 and 50 mA / cm 2 , respectively;

[0067] Finally, the electrode was taken out and washed with deionized water to obtain a Ti / β-PbO2 electrode.

[0068] Comparative Example 2

[0069] The difference from Example 1 is that the heat treatment step after silver plating is omitted, and a Ti / Ag / α-PbO2 / β-PbO2 electrode is prepared.

[0070] Comparative Example 3

[0071] The difference from Example 1 is that the step of electrodeposition of α-PbO2 layer is omitted, and a Ti / Ag / β-PbO2 electrode is prepared.

[0072] Comparative Example 4

[0073] The difference from Example 1 is that the α-PbO2 layer is replaced with a tin-antimony oxide intermediate layer to prepare the Ti / Ag / Zr-SnO2 / β-PbO2 electrode.

[0074] Comparative Example 5

[0075] The difference from Example 1 is that the electrodeposition of the β-PbO2 layer did not employ stepwise electrodeposition, but rather used an electrodeposition rate of 20 mA / cm². 2 Ti / Ag / α-PbO2 / β-PbO2 electrodes were prepared by electrodeposition at a current density of 1000 rpm for 50 min.

[0076] Performance testing and results analysis:

[0077] The titanium-based coated electrodes prepared in the above embodiments and comparative examples were subjected to performance testing and analysis, including the following steps:

[0078] (1) Charge transfer resistance is an important parameter for evaluating the electrochemical performance of an electrode. To further investigate the electrochemical performance of the electrodes, electrochemical impedance spectroscopy (EIS) curves of the Ti / β-PbO2 electrode (Comparative Example 1) and the Ti / Ag / α-PbO2 / β-PbO2 electrode (Example 1) were measured in 0.1 mol / L Na2SO4 solution at an amplitude of 0.01 V and a frequency of 0.1–1 MHz. In the EIS curves, the diameter of the semicircular arc in the high-frequency part of the resistance is used to measure the charge transfer resistance between the substrate and the coated electrode, i.e., the electrode resistance. The smaller the diameter, the smaller the electrode resistance; the larger the diameter, the larger the electrode resistance. Figure 1 As shown, through equivalent circuit fitting, the impedances of the Ti / β-PbO2 and Ti / Ag / α-PbO2 / β-PbO2 electrodes are found to be 11.20 Ω·cm. -2 5.34Ω·cm -2 This indicates that the Ti / Ag / α-PbO2 / β-PbO2 electrode of the present invention has better conductivity.

[0079] (2) Accelerated lifetime testing can evaluate the stability of metal oxide electrodes. Generally, electrode stability is an important performance characteristic in practical applications, and it is often used to investigate the rate at which the PbO2 active layer detaches from the titanium substrate. At a current density of 10000 A / m... 2 Accelerated life tests were conducted on the Ti / β-PbO2 electrode of Comparative Example 1 and the Ti / Ag / α-PbO2 / β-PbO2 electrode of Example 1 in a 15 wt.% H2SO4 aqueous solution using a DC power supply. Voltage changes were recorded to evaluate the stability and lifespan of the electrodes. The test was terminated when the battery voltage exceeded 10V. The results are as follows.Figure 2 As shown, the voltage of the Ti / β-PbO2 electrode exceeded 10V after 5 minutes, reaching 12.78V; while the voltage of the Ti / Ag / α-PbO2 / β-PbO2 electrode only exceeded 10V after 62.183 hours, reaching 15.98V. This indicates that the Ag layer can significantly improve the stability and lifespan of the electrode.

[0080] (3) SEM and EDS can be used to analyze microstructure. The prepared electrodes were scanned. For example... Figure 3 As shown, after three Ag platings and heat treatment in air at 400℃ for 1 hour, the Ag layer essentially covered the Ti substrate, providing protection for the Ti electrode and ensuring good conductivity. Figure 4 As shown, EDS analysis of the Ti / Ag electrode revealed that it was mainly composed of Ti (40.16 wt.%), Ag (53.34 wt.%), and O (6.50 wt.%), indicating that during heat treatment of the Ag layer in air, the Ag was not oxidized and the Ti was essentially completely covered. Figure 5 As shown, the surface of the electrodeposited Ti / Ag / α-PbO2 exhibits a dense structure, which effectively prevents the penetration of reactive oxygen species and improves the stability of the electrode. Figure 6 As shown, EDS analysis of the Ti / Ag / α-PbO2 electrode revealed that it mainly consists of Pb (80.75 wt.%), O (19.12 wt.%), Ti (0.10 wt.%), and a small amount of Ag (0.03 wt.%), indicating that Ag is largely covered. The EDS pattern after scraping off the α-PbO2 layer of the Ti / Ag / α-PbO2 electrode is shown in the figure. Figure 7 As shown, it was found to be mainly composed of Pb (4.26 wt.%), O (22.30 wt.%), Ti (72.72 wt.%), and Ag (0.72 wt.%). Relatively speaking, the Ag content is low, possibly because the Ag layer attached to the Ti substrate was also scraped off during the removal of the α-PbO2 layer. Secondly, it is possible that some Ag layer dissolved under alkaline conditions during electrodeposition and then co-deposited into the α-PbO2 layer. In summary, EDS analysis indicates that an Ag / α-PbO2 interlayer was successfully prepared. Figure 8 As shown, the β-PbO2 active layer has a dense tetrahedral pyramid structure, and new β-PbO2 extends outward from some of the vertices of the pyramid. This structure can effectively prevent reactive oxygen species from penetrating the electrode surface and increase the surface area of ​​the electrode, protecting the outer layer of the electrode from falling off easily, and providing abundant active sites for the efficient electrocatalytic degradation of anthraquinone organic pollutants.

[0081] (4) XRD analysis of crystal structure. For example... Figure 9As shown, the crystal structure of the Ti / Ag / α-PbO2, Ti / Ag / α-PbO2 / β-PbO2 electrode interface was tested and analyzed by XRD. The pattern of the Ti / Ag / α-PbO2 electrode was compared with the standard card of α-PbO2. The characteristic diffraction peaks of the Ti / Ag / α-PbO2 electrode appeared at 36.16°, 60.52°, 76.97°, which corresponded to the (200), (132), (400) crystal planes of the standard α-PbO2 (PDF #41-1416) substance, respectively. Therefore, α-PbO2 was electrodeposited on the Ti / Ag surface, which further proved that the Ti / Ag / α-PbO2 electrode was successfully prepared. The characteristic diffraction peaks of the Ti / Ag / α-PbO2 / β-PbO2 electrode appeared at 31.80°, 36.12°, 62.31°, 76.79°, which corresponded to the (101), (200), (301), (211) crystal planes of the standard β-PbO2 (PDF #41-1492) substance, respectively. Therefore, β-PbO2 was electrodeposited on the Ti / Ag / α-PbO2 surface, which further proved that the Ti / Ag / α-PbO2 / β-PbO2 electrode was successfully prepared.

[0082] (5) With alizarin red S (ARS) solution as the target pollutant, the Ti / Ag / α-PbO2 / β-PbO2 electrode of Example 1 and the electrodes of Comparative Examples 1, 2, 3, 4, 5 were respectively used as the anode, and a platinum sheet electrode with the same size was used as the cathode to degrade the ARS solution with an initial concentration of 30.00 mg / L at a current density of 40 mA / cm2, as shown in Table 4. 2 Figure 10 As shown in Table 4, the degradation rate of Example 1 was 96.49%, the degradation rate of Comparative Example 1 was 94.59%, the degradation rate of Comparative Example 2 was 71.88%, the degradation rate of Comparative Example 3 was 94.34%, the degradation rate of Comparative Example 4 was 54.62%, and the degradation rate of Comparative Example 5 was 81.44%. It is shown that the Ti / Ag / α-PbO2 / β-PbO2 electrode has better electrocatalytic activity, which indicates that the Ti / Ag / α-PbO2 / β-PbO2 electrode has great application potential in the degradation of anthraquinone organic dyes (especially alizarin red S) and other electrochemical technical fields.

[0083] The above is the preferred embodiment of the present application. It should be noted that those skilled in the art can make several improvements and refinements without departing from the principles of the present application, and these improvements and refinements should also be considered within the scope of protection of the present application.​

Claims

1. A method for producing a Ti / Ag / α-PbO2 / β-PbO2 electrode, characterized by, The method comprises the following steps: S1: preparing a mixed acid solution and heating, and then placing the titanium substrate after ultrasonic treatment to etch, to obtain a pretreated titanium substrate; S2: preparing a silver plating solution, placing the pretreated titanium substrate in the silver plating solution to plate silver, taking out the titanium substrate after the silver plating is completed, cleaning the titanium substrate with ultrapure water, and naturally airing or drying; replacing the silver plating solution and repeating the silver plating several times; and then performing high-temperature heat treatment, to obtain a Ti / Ag electrode; wherein the heat treatment temperature is 350-500 ℃. S3: prepare the α-PbO2 plating solution and carry out electrodeposition of the Ti / Ag electrode in the α-PbO2 plating solution, and then wash with deionized water to obtain a Ti / Ag / α-PbO2 electrode; wherein the electrodeposition is carried out at 2-7 mA / cm2 at 30-60 ℃ for 2-5 h. 2 electrodeposition for 2-5 h; S4: prepare a β-PbO2 plating solution and perform electrodeposition of the Ti / Ag / α-PbO2 electrode in the β-PbO2 plating solution, and then wash with deionized water to obtain a Ti / Ag / α-PbO2 / β-PbO2 electrode; wherein, first, electrodeposition is performed at 40-70 ℃ at a current density of 10 mA / cm 2 for 10-30 min; then, electrodeposition is performed at a current density increased by 5 mA / cm 2 for 5 min, and the total electrodeposition time is 30-60 min.

2. The method for preparing a Ti / Ag / α-PbO2 / β-PbO2 electrode according to claim 1, characterized by, In step S1, the thickness of the titanium substrate is any one of 0.1 mm, 0.2 mm, and 0.3 mm; and the mixed acid solution comprises sulfuric acid and tartaric acid.

3. The method for preparing a Ti / Ag / α-PbO2 / β-PbO2 electrode according to claim 1, characterized in that, In step S2, the silver plating solution comprises a silver salt, dilute ammonia water, a strong base, and a reducing aldehyde.

4. The method for preparing a Ti / Ag / α-PbO2 / β-PbO2 electrode according to claim 3, characterized by, The silver salt is silver nitrate, the concentration of which is 2.0-6.0 wt.%; the strong base is any one of sodium hydroxide and potassium hydroxide, the concentration of which is 1.0-4.0 wt.%; the reducing aldehyde is any one of glucose, formaldehyde, and acetaldehyde, the concentration of which is 3.0-7.0 wt.%; and the concentration of the dilute ammonia water is 2.0-10.0 wt.%.

5. The method for preparing a Ti / Ag / α-PbO2 / β-PbO2 electrode according to claim 1, characterized in that, In step S2, the silver plating time is 20-80 min; the silver plating frequency is 1-5 times; and the drying temperature is 30-50 °C.

6. A Ti / Ag / α-PbO2 / β-PbO2 electrode obtained by the preparation method according to any one of claims 1-5.

7. Use of a Ti / Ag / α-PbO2 / β-PbO2 electrode obtained by the preparation method according to any one of claims 1-5 in electrochemical degradation of anthraquinone organic dye wastewater.

8. Use according to claim 7, characterized in that, The anthraquinone organic dye is alizarin red S.

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