Method for preparing Pb-Ag / MnO2 coating anode through pulse deposition

Abstract

The invention provides a method for preparing a Pb-Ag / MnO2 coating anode through pulse deposition, which comprises the following steps: adding a proper amount of manganese-containing metal powder into an acid solution to prepare an electro-deposition solution; the method comprises the following steps: by taking a Pb-Ag substrate as an anode in a deposition system and a platinum electrode as a cathode, carrying out oxidation reaction on manganese ions in an electro-deposition solution by adopting a pulse deposition mode, and depositing the manganese ions on the surface of the Pb-Ag substrate in the forms of beta-MnO2 and gamma-MnO2 to form a Pb-Ag / MnO2 coating anode. According to the method, the manganese ions in the electro-deposition liquid are oxidized in a pulse deposition mode, the manganese ions are deposited on the surface of the Pb-Ag substrate in the forms of beta-MnO2 and gamma-MnO2, the Pb-Ag / MnO2 coating anode is formed, the Pb-Ag / MnO2 coating anode prepared through the method is multiple in crystal form and stable in structure, the stable performance of the Pb-Ag substrate can be kept, the corrosion resistance of the Pb-Ag substrate in the electrolysis process is enhanced, the service life of the Pb-Ag substrate is prolonged, and the service life of the Pb-Ag substrate is prolonged. The double-crystal-phase structure can further improve the oxygen evolution activity of the anode and accelerate the reaction process, and can be applied to the field of industrial electrolysis on a large scale.

Description

Technical Field

[0001] The present application relates to the technical field of hydrometallurgical electrolysis, and in particular to a method for preparing a Pb-Ag / MnO2 coated anode by pulse deposition. Background Art

[0002] Pb-Ag anode, also known as lead-silver anode, is an alloy anode composed of lead and silver. In the electrochemical process, it acts as an anode material and can participate in electrochemical reactions such as oxygen evolution reaction. However, the oxygen evolution activity of Pb-Ag anode is poor, and the corrosion and dissolution of lead are inevitable at high potentials. Therefore, in theory, the oxygen evolution activity can be improved and the amount of lead dissolved can be reduced by alloying the Pb-Ag anode and preparing a coating on the anode surface.

[0003] MnO2 is widely used as anode surface coating because of its low cost and environmental friendliness. However, MnO2 has complex crystal forms and different crystal forms have different performances. If the MnO2 coating is directly electroplated on the Pb-Ag anode, the performance of the Pb-Ag anode will be unstable, the oxygen evolution activity will be low, and the service life will be short. Therefore, it is necessary to propose a method for preparing a Pb-Ag / MnO2 coated anode, so that the Pb-Ag / MnO2 coated anode has the characteristics of stable performance, longer service life and higher oxygen evolution activity. Summary of the invention

[0004] To solve the above problems, the present application provides a method for preparing a Pb-Ag / MnO2 coated anode by pulse deposition, wherein manganese ions in an electrodeposition solution are oxidized by pulse deposition, so that the manganese ions are deposited on the surface of a Pb-Ag substrate in the form of β-MnO2 and γ-MnO2 to form a Pb-Ag / MnO2 coated anode. The Pb-Ag / MnO2 coated anode prepared by the method has multiple crystal forms and a stable structure, and can maintain the stability of the performance of the Pb-Ag substrate, enhance its corrosion resistance during the electrolysis process, reduce lead pollution and extend the service life of the anode. This dual-phase structure can further improve the oxygen evolution activity of the anode, accelerate the reaction process, and can be widely used in the field of industrial electrolysis.

[0005] In a first aspect, the present application provides a method for preparing a Pb-Ag / MnO2 coated anode by pulse deposition, the method comprising:

[0006] Taking an appropriate amount of manganese-containing metal powder and adding it into an acid solution to prepare an electrodeposition solution;

[0007] The Pb-Ag substrate is used as the anode in the deposition system, and the platinum electrode is used as the cathode. A pulse deposition method is used to cause the manganese ions in the electrodeposition solution to undergo an oxidation reaction and deposit on the surface of the Pb-Ag substrate in the form of β-MnO2 and γ-MnO2 to form the Pb-Ag / MnO2 coating anode;

[0008] The current density of the pulse deposition is 1 mA / cm 2 ~5mA / cm 2 The deposition time is 60 min to 180 min, the working ratio is 10% to 40%, and the frequency is 5 Hz to 15 Hz.

[0009] Optionally, the temperature during the pulse deposition is 40° C. to 100° C.

[0010] Optionally, the pulse deposition time is 80 min to 150 min.

[0011] Optionally, the duty cycle of the pulse deposition is 15% to 35%, and the frequency is 8 Hz to 12 Hz.

[0012] Optionally, the manganese-containing metal powder includes manganese sulfate, manganese nitrate, manganese chloride and / or manganese acetate.

[0013] Optionally, the acid solution comprises sulfuric acid, nitric acid, hydrochloric acid and / or acetic acid.

[0014] Optionally, in the electrodeposition solution, the concentration of the manganese ions is 10 g / L to 40 g / L, and the concentration of the acid solution is 20 g / L to 50 g / L.

[0015] Optionally, the Pb-Ag matrix is ​​a pretreated Pb-Ag matrix, and the pretreatment includes:

[0016] After the Pb-Ag substrate is polished, ultrasonic cleaning is performed at a temperature of 40° C. to 100° C. for 2 min to 10 min to remove oil;

[0017] The degreased Pb-Ag substrate is cleaned and dried and then used as the anode in the deposition system.

[0018] Optionally, the cleaning agent for ultrasonic cleaning includes deionized water, anhydrous ethanol or acetone.

[0019] In a second aspect, the present application provides a Pb-Ag / MnO2 coated anode obtained by the method for preparing a Pb-Ag / MnO2 coated anode by pulse deposition as described in the first aspect above, wherein the Pb-Ag / MnO2 coated anode consists of a Pb-Ag matrix and a MnO2 coating;

[0020] Wherein, the crystal phase composition of the MnO2 includes β-MnO2 and γ-MnO2.

[0021] In summary, the present application includes at least one of the following beneficial technical effects:

[0022] 1. The present application provides a method for preparing a Pb-Ag / MnO2 coated anode by pulse deposition, wherein the manganese ions in the electrodeposition solution are oxidized by pulse deposition, and then the two crystal phases of β-MnO2 and γ-MnO2 are synthesized into a three-dimensional spherical two-phase structure by controlling the current density, electroplating time, frequency and working ratio, and uniformly deposited on the surface of the Pb-Ag substrate to form a Pb-Ag / MnO2 coated anode; wherein, by controlling the current density and electroplating time during pulse deposition, the crystal structure of the deposited MnO2 can be accurately controlled to obtain a coating with small grain size, high density, brightness and uniformity, and the prepared Pb-Ag / MnO2 coated anode has higher oxygen evolution activity, and only requires a lower voltage to drive the oxygen evolution reaction, thereby reducing energy consumption; at the same time, the MnO2 coating can further protect the Pb-Ag substrate, reduce the corrosion and dissolution of lead, and improve the lead pollution. The Pb-Ag anode deposited with the MnO2 coating has stable performance and a longer service life;

[0023] 2. The present application provides a Pb-Ag / MnO2 coated anode, which is composed of a Pb-Ag matrix and a MnO2 coating. The crystal phase composition of MnO2 includes β-MnO2 and γ-MnO2, wherein β-MnO2 is a rutile structure with the strongest acid resistance, and γ-MnO2 has better oxygen evolution activity. β-MnO2 and γ-MnO2 are synthesized so that the coating material has the characteristics of strong stability and high oxygen evolution activity. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the description of the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0025] Figure 1 A flow chart of a method for preparing a Pb-Ag / MnO2 coated anode by pulse deposition provided in an embodiment of the present application is shown;

[0026] Figure 2 The element distribution diagram of the Pb-Ag / MnO2 coated anode provided in the embodiment of the present application is shown;

[0027] Figure 3 An energy dispersive X-ray spectroscopy analysis diagram of a Pb-Ag / MnO2 coated anode provided in an embodiment of the present application is shown;

[0028] Figure 4 A scanning electron microscope image of a Pb-Ag / MnO2 coated anode provided in an embodiment of the present application is shown;

[0029] Figure 5 A linear sweep voltammetry comparison diagram of a Pb-Ag / MnO2 coated anode provided in an embodiment of the present application and a Pb-Ag anode without a deposited coating is shown;

[0030] Figure 6 A comparison chart of the service life of the Pb-Ag / MnO2 coated anode provided in the embodiment of the present application and the Pb-Ag anode without a deposited coating is shown;

[0031] Figure 7 The X-ray diffraction patterns of Pb-Ag / MnO2-1, Pb-Ag / MnO2-2, and Pb-Ag / MnO2-3 prepared in the examples of the present application are shown. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0033] In the drawings, the size of the constituent elements, the thickness of the layer or the area may be exaggerated for the sake of clarity. Therefore, any implementation of the present disclosure is not necessarily limited to the size shown in the drawings, and the shapes and sizes of the components in the drawings do not reflect the true proportions. In addition, the drawings schematically show ideal examples, and any implementation of the present disclosure is not limited to the shapes or values ​​shown in the drawings.

[0034] In the related technology, Pb-Ag anode is the most widely used anode material in zinc electrowinning metallurgical process. However, the oxygen evolution activity of Pb-Ag anode is poor. Under high potential, lead corrosion and dissolution are inevitable, which not only leads to the deactivation of Pb-Ag anode but also brings lead pollution to the industrial environment and zinc products. With the gradual improvement of energy-saving and environmental protection requirements, Pb-Ag anode is increasingly difficult to apply to the development of green industrial system. How to reduce the lead pollution of Pb-Ag anode and improve its oxygen evolution catalytic activity and reduce energy consumption has become a problem that needs to be solved urgently.

[0035] In recent years, a lot of research has been conducted on new Pb-Ag anode materials with high oxygen evolution activity and high corrosion resistance. There are two main research directions, mainly anode alloying and anode surface coating preparation. Multi-element alloying can improve the corrosion resistance and mechanical strength of the anode, but it has little inhibitory effect on lead dissolution, and the oxidative dissolution of multiple metal elements will also affect the stability of the electrolysis process; the anode surface coating preparation is to coat the surface of the Pb-Ag anode substrate with a highly active coating by electroplating, thereby improving the corrosion resistance of the anode.

[0036] At present, the research on Pb-Ag anode coating is still in the experimental stage and has not formed a mature theory. The high-activity and low-cost coatings with relatively promising application prospects in the field of Pb-Ag anodes mainly include oxide coatings such as PbO2, CeO2 and MnO2. Among them, manganese dioxide (MnO2) is considered to be the most attractive Pb-Ag anode coating material because of its low cost, environmental friendliness and no new impurities introduced into the electrolytic zinc system.

[0037] MnO2 is composed of MnO6 octahedral units, which share angles or edges to form various tunnel and layer structures. MnO2 is mainly classified into α, β, γ, λ and δ crystal forms. The phase activity relationship and catalytic activity source of these multiphase MnO2 are still unclear and controversial. If MnO2 is directly electroplated on the surface of Pb-Ag anode, the performance of Pb-Ag anode matrix will be unstable, which is not conducive to electrolysis reaction.

[0038] According to experiments, the present invention has found that among various crystal forms of MnO2, β-MnO2 is the most acid-resistant rutile structure. Attaching it to the anode surface can enhance the corrosion resistance of the anode material, but its oxygen evolution activity is poor, which is not conducive to the electrolysis reaction; while γ-MnO2 exhibits the highest oxygen evolution (OER) activity in an acidic environment, and the present invention has found in its stability test that the Pb-Ag anode with a γ-MnO2 coating has a high oxygen evolution (OER) activity at 10 mA / cm 2 It can run for hundreds of hours at low current density, which is a good example of γ-MnO2 in electrolysis (50mA / cm 2 ) provides theoretical support for its long-term operation in the field.

[0039] Based on the above theoretical research, how to further improve the oxygen evolution activity of the anode matrix while ensuring the stability of the anode material is an urgent problem to be solved.

[0040] Based on this, the present application provides a method for preparing a Pb-Ag / MnO2 coated anode by pulse deposition. The two crystal phases of β-MnO2 and γ-MnO2 are synthesized by pulse deposition and uniformly deposited on the surface of the Pb-Ag anode substrate. The formed Pb-Ag / MnO2 coated anode has the characteristics of high stability and high oxygen evolution activity.

[0041] Specifically, Figure 1 The flowchart of the method for preparing a Pb-Ag / MnO2 coated anode by pulse deposition proposed in the embodiment of the present application is shown as follows: Figure 1 As shown, the method for preparing a Pb-Ag / MnO2 coated anode by pulse deposition specifically includes the following steps:

[0042] Step S1: taking an appropriate amount of manganese-containing metal powder and adding it into an acid solution to prepare an electrodeposition solution;

[0043] Step S2: The Pb-Ag substrate is used as the anode in the deposition system, and the platinum electrode is used as the cathode. A pulse deposition method is used to cause the manganese ions in the electrodeposition solution to undergo an oxidation reaction and deposit on the surface of the Pb-Ag substrate in the form of β-MnO2 and γ-MnO2 to form a Pb-Ag / MnO2 coated anode;

[0044] Step S3: wherein the current density of the pulse deposition is 1 mA / cm 2 ~5mA / cm 2 The deposition time is 60 min to 180 min, the working ratio is 10% to 40%, and the frequency is 5 Hz to 15 Hz.

[0045] It should be noted that pulse deposition is a type of electrodeposition, which is different from electroplating:

[0046] First, in terms of working principle, electrodeposition is the process of forming a metal coating by depositing metal ions in the form of oxides onto the surface of a workpiece. In contrast, electroplating is the process of providing protection and decoration by depositing a layer of metal coating on the surface of a workpiece. Therefore, pulse deposition is more capable of controlling the structure of the coating than electroplating.

[0047] Secondly, in the use of electrolyte solutions, electrodeposition usually uses electrolyte solutions containing metal ions; while the electrolyte solution of electroplating usually contains ions of the metal to be plated and other additives, such as inhibitors and enhancers. It can be seen that pulse deposition has lower preparation costs than electroplating, and the deposition process produces less waste, and the post-processing steps are more convenient and simple.

[0048] Finally, in terms of application purpose, electroplating is more for forming a decorative layer on the electrode surface to improve wear resistance, reflectivity and enhance aesthetics, while the coating prepared by electrodeposition is mainly to change the coating structure to obtain a coating with better performance.

[0049] In summary, pulse deposition has more advantages than traditional electroplating methods. For example, the prepared coating not only has more stable performance, but also can control the structure of the coating by controlling parameters such as current density and temperature. Fewer reagents are required for electrodeposition, which greatly saves preparation costs and achieves higher economic benefits on the one hand, and reduces reagent post-processing and other operational steps on the other hand, reducing the difficulty of preparation.

[0050] It should be noted that the manganese-containing metal powder is used to provide manganese ions;

[0051] The electrodeposition solution is used as a deposition system during pulse deposition, and the anode and cathode materials are placed in the electrodeposition solution for pulse deposition.

[0052] In the embodiment of the present application, after oxidizing the manganese ions in the electrodeposition solution by pulse deposition, the manganese ions are deposited on the surface of the Pb-Ag substrate in the form of a twin-phase structure of β-MnO2 and γ-MnO2. The formed Pb-Ag / MnO2 coating anode has stable performance and a longer service life. In addition, the preparation method is simple and easy to operate, requires less reagents, is conducive to saving preparation costs, and has less waste after the reaction, which meets the requirements of green and environmentally friendly production operations.

[0053] The present application utilizes pulse deposition to prepare a MnO2 coating with a specific crystal phase structure. In addition, it can further synthesize two specific crystal phases of MnO2, solving the problem of unstable MnO2 coating structure. During pulse deposition, by adjusting the current density, deposition time, frequency and working ratio, when controlling the synthesis of the two crystal phase structures of β-MnO2 and γ-MnO2, the nucleation rate can be effectively slowed down, giving the MnO2 coating material more defects, thereby improving the oxygen evolution activity of the coating material.

[0054] The MnO2 coating with a dual-phase structure prepared in the present application solves the problem of single-phase MnO2 coating having single performance, so that the anode material with this coating can have the characteristics of high corrosion resistance and high oxygen evolution activity.

[0055] In some embodiments, the current density of the pulse deposition can be 1 mA / cm 2 , 2mA / cm 2 , 3mA / cm 2 , 4mA / cm 2 or 5mA / cm 2 .

[0056] In the embodiment of the present application, Pb-Ag is used as the anode substrate and a platinum electrode is used as the cathode. A pulse power supply is used to perform pulse deposition at a low current density, so that the two crystal structures of β-MnO2 and γ-MnO2 can be synthesized into a three-dimensional spherical twin phase (β and γ) structure, and the structure is uniformly deposited on the surface of the Pb-Ag anode substrate to form a Pb-Ag / MnO2 coated anode.

[0057] In some embodiments, the temperature during pulse deposition is 40° C. to 100° C.

[0058] Specifically, the temperature during pulse deposition can be 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, or 100°C.

[0059] Since the temperature during pulse deposition will affect the microstructure and surface morphology of the coating, setting the temperature within the range of 40°C to 100°C can control the synthesis of manganese ions in the two crystal structures of β-MnO2 and γ-MnO2; at the temperature of the pulse deposition, the migration rate of manganese ions increases, which is conducive to the rapid formation of the coating and improves the deposition efficiency; at the temperature of the pulse deposition, the bonding between the formed MnO2 coating and the Pb-Ag matrix can be promoted, the bonding force can be enhanced, and the adhesion and durability of the MnO2 coating can be improved.

[0060] In some embodiments, the pulse deposition time is 80 min to 150 min.

[0061] Specifically, the time of pulse deposition can be 80 min, 85 min, 90 min, 95 min, 100 min, 105 min, 110 min, 115 min, 120 min, 125 min, 130 min, 135 min, 140 min, 145 min, or 150 min.

[0062] The pulse time will affect the deposition rate and the crystal structure of the coating. By controlling the pulse time within the range of 80 min to 150 min and combining it with a suitable pulse current density, specific β-MnO2 and γ-MnO2 can be deposited on the Pb-Ag surface to form a MnO2 coating with high density and stable performance.

[0063] In some embodiments, the duty cycle during pulse deposition is 15% to 35%, and the frequency is 8 Hz to 12 Hz.

[0064] Specifically, the working ratio during pulse deposition is 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, 34%, and 35%.

[0065] Specifically, the frequencies during pulse deposition are 8 Hz, 9 Hz, 10 Hz, 11 Hz, and 12 Hz.

[0066] By controlling the frequency of pulse deposition, the rate of pulse deposition can be controlled to avoid excessive deposition, which helps to reduce the nucleation rate and form more defects on the coating to improve the oxygen evolution activity of the coating.

[0067] In some embodiments, the manganese-containing metal powder includes manganese sulfate, manganese nitrate, manganese chloride, and / or manganese acetate.

[0068] Preferably, the manganese-containing metal powder is manganese sulfate or manganese acetate.

[0069] In some embodiments, the acid solution includes sulfuric acid, nitric acid, hydrochloric acid, and / or acetic acid.

[0070] Preferably, the acid solution is sulfuric acid or acetic acid.

[0071] In some embodiments, in the electrodeposition solution, the concentration of manganese ions is 10 g / L to 40 g / L, and the concentration of the acid solution is 20 to 50 g / L.

[0072] Specifically, in the electrodeposition solution, the concentration of manganese ions is 10 g / L, 15 g / L, 20 g / L, 25 g / L, 30 g / L, 35 g / L, and 40 g / L.

[0073] By controlling the concentration of manganese ions, the thickness of the coating deposited on the Pb-Ag surface is made uniform, thereby obtaining a high-quality coating.

[0074] Specifically, in the electrodeposition solution, the concentration of the acid solution is 20 g / L, 25 g / L, 30 g / L, 35 g / L, 40 g / L, 45 g / L, and 50 g / L.

[0075] Controlling the concentration of the acid solution can help form a uniform and dense MnO2 coating and improve the coating quality.

[0076] In some embodiments, the Pb-Ag substrate is a pretreated Pb-Ag substrate, and the pretreatment includes:

[0077] After the Pb-Ag substrate is polished, it is ultrasonically cleaned at 40°C to 100°C for 2min to 10min to remove oil;

[0078] The degreased Pb-Ag substrate is cleaned and dried and then used as the anode in the deposition system.

[0079] The above-mentioned Pb-Ag substrate is ground and polished until the surface has an obvious metallic luster, so that the surface of the Pb-Ag substrate is flat, so that the subsequently deposited MnO2 coating can be evenly adhered to the surface of the Pb-Ag substrate, increasing the contact area between the MnO2 coating and the surface of the Pb-Ag substrate, enhancing the bonding force, and preventing the MnO2 coating from falling off during the electrolysis process.

[0080] In some embodiments, the Pb-Ag substrate may be polished using water-abrasive sandpaper, dry-abrasive sandpaper, flocked sandpaper, etc. The specific type of sandpaper is not specifically limited in the embodiments of the present application.

[0081] Specifically, after the Pb-Ag substrate is ground and polished, ultrasonic cleaning is performed at a temperature of 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C or 100°C.

[0082] Specifically, ultrasonic cleaning is performed for 2 min, 3 min, 4 min, 5 min, 6 min, 7 min, 8 min, 9 min or 10 min to remove oil, so as to prevent the oil on the Pb-Ag surface from contaminating the electrodeposition solution and affecting the deposition effect. After degreasing, the Pb-Ag surface is more susceptible to deposition of MnO2, and the bonding force between the two is enhanced, making the coating stronger.

[0083] After degreasing, the Pb-Ag substrate is cleaned and dried to remove the ultrasonic cleaning agent on the surface, so that the surface of the Pb-Ag substrate remains clean and tidy, and the deposition affected by other ions is reduced.

[0084] In some embodiments, the cleaning agent for ultrasonic cleaning includes deionized water, anhydrous ethanol or acetone.

[0085] The above reagents can quickly remove the oil stains on the surface of the Pb-Ag substrate, keeping the surface of the Pb-Ag substrate dry and clean, so that the subsequent pulse-deposited MnO2 can be better attached.

[0086] In a second aspect, the present application provides a Pb-Ag / MnO2 coated anode obtained by the method for preparing a Pb-Ag / MnO2 coated anode by pulse deposition according to the first aspect above, wherein the Pb-Ag / MnO2 coated anode consists of a Pb-Ag matrix and a MnO2 coating; wherein the crystal phase composition of MnO2 includes β-MnO2 and γ-MnO2.

[0087] The MnO2 coating with a dual crystal structure of highly active γ-MnO2 and highly stable β-MnO2 prepared by pulse deposition has a three-dimensional surface and better hydrophilicity and gas repellency, which is conducive to the rapid oxygen evolution reaction.

[0088] Compared with the Pb-Ag anode matrix, its overpotential in the electrolysis process is reduced by 126mV, and a lower voltage can be achieved to drive the oxygen evolution reaction, thereby reducing energy consumption; the cell voltage is reduced by 0.08V, and the current efficiency is increased by 5% to 10%, effectively improving the electrolysis efficiency of the electrolysis process; not only that, it can also enhance the corrosion resistance and acid resistance of the Pb-Ag anode at high potential, reduce the amount of lead dissolved, protect the anode, reduce lead pollution, and increase the service life of the anode. According to experiments in sulfuric acid medium, 2A / cm 2 The lifespan under accelerated current is increased by 50 hours, and it can be widely used in the field of industrial electrolysis.

[0089] The technical solution provided by the present invention is further described below with reference to examples, but the scope of protection claimed in the present invention is not limited to the scope of the implementation description.

[0090] Example

[0091] Example 1

[0092] A method for preparing a Pb-Ag / MnO2 coated anode by pulse deposition:

[0093] 1. Use water-abrasive sandpaper to polish the Pb-Ag anode substrate until the surface of the Pb-Ag anode substrate is flat, smooth, and has obvious metallic luster;

[0094] 2. Put the polished Pb-Ag anode into deionized water, and clean it ultrasonically at 100°C for 10 minutes to remove oil stains, then wash it with deionized water, and dry it for later use;

[0095] 3. Take 55g of manganese sulfate powder and add it to 1L of sulfuric acid solution with a concentration of 50g / L to prepare an electrodeposition solution so that the manganese ion concentration in the electrodeposition solution is 20g / L;

[0096] 4. The dried Pb-Ag anode substrate is used as the anode of the deposition system, and the platinum electrode is used as the cathode. Then a pulse power supply is used, and its frequency is set to 10 Hz, the working ratio is 20%, and the current density is 2 mA / cm 2 Pulse deposition was carried out under the conditions of 400 ℃ and 800 ℃, so that the manganese ions in the electrodeposition solution underwent oxidation reaction and were deposited on the surface of the Pb-Ag substrate in the form of β-MnO2 and γ-MnO2. The temperature during deposition was set to 70℃. After 180 minutes of deposition, a Pb-Ag / MnO2 coated anode was obtained.

[0097] Example 2

[0098] A method for preparing a Pb-Ag / MnO2 coated anode by pulse deposition:

[0099] 1. Use water-abrasive sandpaper to grind and polish the Pb-Ag anode substrate until the surface of the Pb-Ag anode substrate is flat, smooth, and has obvious metallic luster;

[0100] 2. Put the polished Pb-Ag anode into deionized water, and clean it ultrasonically at 50°C for 5 minutes to remove oil stains, then wash it with deionized water, and dry it for later use;

[0101] 3. Take 27.5g of manganese sulfate powder and add it to 1L of sulfuric acid solution with a concentration of 20g / L to prepare an electrodeposition solution so that the manganese ion concentration in the electrodeposition solution is 10g / L;

[0102] 4. The dried Pb-Ag anode substrate is used as the anode of the deposition system, and the platinum electrode is used as the cathode. Then a pulse power supply is used, and its frequency is set to 5 Hz, the working ratio is 10%, and the current density is 1 mA / cm 2 Pulse deposition was carried out under the conditions of 40 °C to cause the manganese ions in the electrodeposition solution to undergo an oxidation reaction and be deposited on the surface of the Pb-Ag substrate in the form of β-MnO2 and γ-MnO2. The deposition temperature was set to 40 °C. After 120 min of deposition, a Pb-Ag / MnO2 coated anode was obtained.

[0103] Example 3

[0104] A method for preparing a Pb-Ag / MnO2 coated anode by pulse deposition:

[0105] 1. Use water-abrasive sandpaper to grind and polish the Pb-Ag anode substrate until the surface of the Pb-Ag anode substrate is flat, smooth, and has obvious metallic luster;

[0106] 2. Put the polished Pb-Ag anode into deionized water and clean it ultrasonically at 40°C for 2 minutes to remove oil stains, then wash it with anhydrous ethanol and dry it for later use;

[0107] 3. Take 110g of manganese sulfate powder and add it to 1L of sulfuric acid solution with a concentration of 40g / L to prepare an electrodeposition solution so that the manganese ion concentration in the electrodeposition solution is 40g / L;

[0108] 4. The dried Pb-Ag anode substrate is used as the anode of the deposition system, and the platinum electrode is used as the cathode. Then a pulse power supply is used, and its frequency is set to 15 Hz, the working ratio is 40%, and then the current density is 5 mA / cm 2 Pulse deposition was carried out under the condition of 100 °C. The manganese ions in the electrodeposition solution underwent oxidation reaction and were deposited on the surface of the Pb-Ag substrate in the form of β-MnO2 and γ-MnO2. The temperature during deposition was set to 100 °C. After 60 minutes of deposition, a Pb-Ag / MnO2 coated anode was obtained.

[0109] Example 4

[0110] A method for preparing a Pb-Ag / MnO2 coated anode by pulse deposition:

[0111] 1. Use water-abrasive sandpaper to polish the Pb-Ag anode substrate until the surface of the Pb-Ag anode substrate is flat, smooth, and has obvious metallic luster;

[0112] 2. Put the polished Pb-Ag anode into deionized water, and clean it ultrasonically at 100°C for 10 minutes to remove oil stains, then wash it with deionized water, and dry it for later use;

[0113] 3. Take 55g of manganese acetate powder and add it to 1L of manganese acetate solution with a concentration of 40g / L to prepare an electrodeposition solution so that the manganese ion concentration in the electrodeposition solution is 30g / L;

[0114] 4. The dried Pb-Ag anode substrate is used as the anode of the deposition system, and the platinum electrode is used as the cathode. Then a pulse power supply is used, and its frequency is set to 10 Hz, the working ratio is 20%, and then the current density is 2 mA / cm 2 Pulse deposition was carried out under the conditions of 400 ℃ and 800 ℃, so that the manganese ions in the electrodeposition solution underwent oxidation reaction and were deposited on the surface of the Pb-Ag substrate in the form of β-MnO2 and γ-MnO2. The temperature during deposition was set to 70℃. After 80 minutes of deposition, a Pb-Ag / MnO2 coated anode was obtained.

[0115] Example 5

[0116] A method for preparing a Pb-Ag / MnO2 coated anode by pulse deposition:

[0117] 1. Use water-abrasive sandpaper to polish the Pb-Ag anode substrate until the surface of the Pb-Ag anode substrate is flat, smooth, and has obvious metallic luster;

[0118] 2. Put the polished Pb-Ag anode into deionized water, and clean it ultrasonically at 100°C for 10 minutes to remove oil stains, then wash it with deionized water, and dry it for later use;

[0119] 3. Take 55g of manganese nitrate powder and manganese acetate powder and add them to 1L of manganese acetate solution with a concentration of 40g / L to prepare an electrodeposition solution so that the manganese ion concentration in the electrodeposition solution is 30g / L;

[0120] 4. The dried Pb-Ag anode substrate is used as the anode of the deposition system, and the platinum electrode is used as the cathode. Then a pulse power supply is used, and its frequency is set to 10 Hz, the working ratio is 20%, and then the current density is 2 mA / cm 2 Pulse deposition was carried out under the conditions of 400 ℃ and 800 ℃, so that the manganese ions in the electrodeposition solution underwent oxidation reaction and were deposited on the surface of the Pb-Ag substrate in the form of β-MnO2 and γ-MnO2. The temperature during deposition was set to 70℃. After deposition for 150 minutes, a Pb-Ag / MnO2 coated anode was obtained.

[0121] Example 6

[0122] A method for preparing a Pb-Ag / MnO2 coated anode by pulse deposition:

[0123] 1. Use water-abrasive sandpaper to polish the Pb-Ag anode substrate until the surface of the Pb-Ag anode substrate is flat, smooth, and has obvious metallic luster;

[0124] 2. Put the polished Pb-Ag anode into deionized water, and clean it ultrasonically at 100°C for 10 minutes to remove oil stains, then wash it with deionized water, and dry it for later use;

[0125] 3. Take 55g of manganese sulfate powder and add it to 1L of a mixed acid solution of manganese sulfate and manganese acetate with a concentration of 50g / L to prepare an electrodeposition solution so that the manganese ion concentration in the electrodeposition solution is 20g / L;

[0126] 4. The dried Pb-Ag anode substrate is used as the anode of the deposition system, and the platinum electrode is used as the cathode. Then a pulse power supply is used, and its frequency is set to 10 Hz, the working ratio is 20%, and then the current density is 2 mA / cm 2 Pulse deposition was carried out under the conditions of 400 ℃ and 800 ℃, so that the manganese ions in the electrodeposition solution underwent oxidation reaction and were deposited on the surface of the Pb-Ag substrate in the form of β-MnO2 and γ-MnO2. The temperature during deposition was set to 70℃. After 180 minutes of deposition, a Pb-Ag / MnO2 coated anode was obtained.

[0127] Comparative Example

[0128] Comparative Example 1

[0129] The difference between Comparative Example 1 and Example 1 is that: Comparative Example 1 adopts constant current to prepare Pb-Ag / MnO2 coated anode, and its current density is 2mA / cm 2 .

[0130] Comparative Example 2

[0131] The difference between Comparative Example 2 and Example 1 is that: Comparative Example 2 adopts stirring deposition to prepare Pb-Ag / MnO2 coated anode, and its current density is 2mA / cm 2 .

[0132] First, based on the above-mentioned Examples 1-6, the element distribution in the Pb-Ag / MnO2 coated anode prepared in Examples 1-6 was detected. Since the detection results of Examples 2-6 are almost the same as those of Example 1, Example 1 is used as an example for detection, and only the image of Example 1 is shown. The detection results are shown in Figure 2 and Figure 3 .

[0133] Figure 2 The element distribution diagram of the Pb-Ag / MnO2 coated anode provided in the embodiment of the present application is shown; Figure 2 “d1” shows the distribution diagram of the total elements, “d2” shows the distribution diagram of the O element, “d3” shows the distribution diagram of the Pb element, and “d4” shows the distribution diagram of the Mn element.

[0134] according to Figure 2 It can be obtained that the Pb-Ag / MnO2 coated anode includes three elements: O, Pb and Mn, indicating that by adopting the preparation method of the embodiment of the present application, the manganese ions in the electrodeposition solution can be deposited on the surface of the Pb-Ag substrate in the form of MnO2 to form a Pb-Ag / MnO2 coated anode.

[0135] Figure 3 An energy dispersive X-ray spectroscopy analysis diagram of a Pb-Ag / MnO2 coated anode provided in an embodiment of the present application is shown; Figure 3 The "d5" in the figure only indicates the drawing number.

[0136] according to Figure 3 It can be obtained that the content of Mn element is 35.4%, the content of O element is 32.7%, and the content of Pb element is 31.9%. It can be seen that the elements are evenly distributed, which confirms that the Pb-Ag / MnO2 coating is uniform and makes the performance of the Pb-Ag / MnO2 coated anode stable.

[0137] The microscopic surface structure of the Pb-Ag / MnO2 coated anode prepared in Example 1 was further tested. The test results are shown in Figure 4 .

[0138] Figure 4 A scanning electron microscope image of a Pb-Ag / MnO2 coated anode provided in an embodiment of the present application is shown; Figure 4 "a" in the figure shows an image magnified 200 times, "b" shows an image magnified 1000 times, and "c" shows an image magnified 5000 times.

[0139] Since the microscopic surface structures of the Pb-Ag / MnO2 coatings prepared in Examples 2-6 and Example 1 are similar, only the images of Example 1 are shown.

[0140] according to Figure 4 It can be obtained that a three-dimensional spherical two-phase (β and γ) structure is formed on the surface of the Pb-Ag / MnO2 coated anode, indicating that the preparation method of the embodiment of the present application can synthesize β-MnO2 and γ-MnO2 into a three-dimensional structure and uniformly deposit it on the surface of the Pb-Ag anode. The formed Pb-Ag / MnO2 coated anode has the performance of both crystal phase structures.

[0141] The linear sweep voltammetry images of the Pb-Ag / MnO2 coated anode prepared in Example 1 and the Pb-Ag anode without coating were further detected.

[0142] Specifically, the Pb-Ag / MnO2 coated anode prepared above was encapsulated with resin, and the encapsulation area was 1×1 cm 2 ;

[0143] An electrochemical workstation was used for LSV electrochemical testing, where the auxiliary electrode was a 20×20 mm platinum electrode, the reference electrode was saturated mercurous sulfate (MSE), the test environment was a 0.5 M sulfuric acid solution, and the test voltage was converted to standard hydrogen voltage (RHE). The LSV test rate was 10 mV / s, and the scanning range was 1.0-2.0 V vs. RHE.

[0144] Figure 5 A linear sweep voltammetry comparison diagram of a Pb-Ag / MnO2 coated anode provided in an embodiment of the present application and a Pb-Ag anode without a deposited coating is shown; Figure 5 The solid line in the figure represents the Pb-Ag / MnO2 coated anode, and the dotted line represents Pb-Ag.

[0145] according to Figure 5 It can be seen from the LSV diagram that the oxygen evolution activity of the twin-phase Pb-Ag / MnO2 coated anode is much better than that of the Pb-Ag anode. The twin-phase Pb-Ag / MnO2 anode has a voltage of about 1.5V and a current of 10mA / cm 2 The oxygen evolution reaction begins to occur at 1.8 V, while the Pb-Ag anode does not react until about 1.8 V. And from the LSV slope analysis of the kinetic performance of the oxygen evolution reaction, the slope of the Pb-Ag / MnO2 anode is smaller, that is, the Tafel slope is smaller, and the kinetic performance is better.

[0146] The service life of the Pb-Ag / MnO2 coated anode prepared in Example 1 and the Pb-Ag anode without a deposited coating were further tested.

[0147] Specifically, the Pb-Ag / MnO2 coated anode prepared above was packaged with the Pb-Ag anode without coating, and the packaging area was 1×1 cm 2 ;

[0148] The accelerated life test was carried out using a constant current voltage and two-electrode system with a test current of 2A / cm 2 The counter electrode is a 20×20mm platinum electrode, the test environment is a 0.5M sulfuric acid solution, and the voltage rises by 5V and shows a very upward trend, which is judged as failure.

[0149] Figure 6 A comparison chart of the service life of the Pb-Ag / MnO2 coated anode provided in the embodiment of the present application and the Pb-Ag anode without a deposited coating is shown; Figure 6 In the figure, “■” indicates a Pb-Ag / MnO2 coated anode, and “●” indicates a Pb-Ag anode without a deposited coating.

[0150] according to Figure 6 It can be seen that the service life of the Pb-Ag / MnO2 coated anode is 2A / cm2 less than that of the uncoated Pb-Ag anode. 2 Under the accelerating current of , the extension time is more than 50 hours. It can be seen that the MnO2 coating prepared by pulse deposition can effectively protect the Pb-Ag anode substrate, reduce the solubility of lead in the electrolysis process, maintain the stability of the Pb-Ag anode substrate, thereby extending its service life, and can also reduce the number of times the damaged Pb-Ag anode substrate is replaced, reducing production costs.

[0151] The crystal phase structures of the MnO2 coatings prepared in Example 1, Comparative Example 1 and Comparative Example 2 were respectively detected. The material prepared in Example 1 was named Pb-Ag / MnO2-1, the material prepared in Comparative Example 1 was named Pb-Ag / MnO2-2, and the material prepared in Comparative Example 2 was named Pb-Ag / MnO2-3. The test results are shown in Figure 7 . Figure 7 The X-ray diffraction patterns of Pb-Ag / MnO2-1, Pb-Ag / MnO2-2, and Pb-Ag / MnO2-3 prepared in the examples of the present application are shown. It can be seen from the figure that the MnO2 in the constant current deposition and stirring deposition is only β-MnO2, while the MnO2 in the pulse deposition process has a dual phase structure of β-MnO2 and γ-MnO2.

[0152] In summary, the present application prepares a coating with a dual crystal structure of highly active γ-MnO2 and highly stable β-MnO2 by pulse deposition. The coating surface is three-dimensional, with better hydrophilicity and gas repellency, which is more conducive to the oxygen evolution reaction. In the sulfuric acid medium, at 2A / cm2 The lifespan under accelerated current is increased by 50 hours, and it can be widely used in the field of industrial electrolysis.

[0153] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0154] Although the preferred embodiments of the present application have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the embodiments of the present application.

[0155] Finally, it should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or terminal device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or terminal device. In the absence of further restrictions, the elements defined by the sentence "including one..." do not exclude the existence of other identical elements in the process, method, article or terminal device including the elements.

[0156] The above is a detailed introduction to the method for preparing Pb-Ag / MnO2 coated anode by pulse deposition provided by the present application. Specific examples are used in this article to illustrate the principles and implementation methods of the present application. The description of the above embodiments is only used to help understand the method of the present application and its core idea; at the same time, for general technicians in this field, according to the ideas of the present application, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as a limitation on the present application.

Claims

1. A method for preparing a Pb-Ag / MnO2 coated anode by pulse deposition, characterized in that: The method comprises: Taking an appropriate amount of manganese-containing metal powder and adding it into an acid solution to prepare an electrodeposition solution; The Pb-Ag substrate is used as the anode in the deposition system, and the platinum electrode is used as the cathode. A pulse deposition method is used to cause the manganese ions in the electrodeposition solution to undergo an oxidation reaction and deposit on the surface of the Pb-Ag substrate in the form of β-MnO2 and γ-MnO2 to form the Pb-Ag / MnO2 coating anode; The current density of the pulse deposition is 1 mA / cm 2 ~5mA / cm 2 The deposition time is 60 min to 180 min, the working ratio is 10% to 40%, and the frequency is 5 Hz to 15 Hz.

2. The method for preparing a Pb-Ag / MnO2 coated anode by pulse deposition according to claim 1, characterized in that: The temperature during the pulse deposition is 40°C to 100°C.

3. The method for preparing a Pb-Ag / MnO2 coated anode by pulse deposition according to claim 1, characterized in that: The pulse deposition time is 80 min to 150 min.

4. The method for preparing a Pb-Ag / MnO2 coated anode by pulse deposition according to claim 1, characterized in that: The working ratio during the pulse deposition is 15% to 35%, and the frequency is 8 Hz to 12 Hz.

5. The method for preparing a Pb-Ag / MnO2 coated anode by pulse deposition according to claim 1, characterized in that: The manganese-containing metal powder includes manganese sulfate, manganese nitrate, manganese chloride and / or manganese acetate.

6. The method for preparing a Pb-Ag / MnO2 coated anode by pulse deposition according to claim 1, characterized in that: The acid solution includes sulfuric acid, nitric acid, hydrochloric acid and / or acetic acid.

7. The method for preparing a Pb-Ag / MnO2 coated anode by pulse deposition according to claim 1, characterized in that: In the electrodeposition solution, the concentration of the manganese ions is 10 g / L to 40 g / L, and the concentration of the acid solution is 20 g / L to 50 g / L.

8. The method for preparing a Pb-Ag / MnO2 coated anode by pulse deposition according to claim 1, characterized in that: The Pb-Ag matrix is ​​a pretreated Pb-Ag matrix, and the pretreatment includes: After the Pb-Ag substrate is polished, ultrasonic cleaning is performed at a temperature of 40° C. to 100° C. for 2 min to 10 min to remove oil; The degreased Pb-Ag substrate is cleaned and dried and then used as the anode in the deposition system.

9. The method for preparing a Pb-Ag / MnO2 coated anode by pulse deposition according to claim 8, characterized in that: The cleaning agent used for ultrasonic cleaning includes deionized water, anhydrous ethanol or acetone.

10. A Pb-Ag / MnO2 coated anode obtained by the method for preparing a Pb-Ag / MnO2 coated anode by pulse deposition according to any one of claims 1 to 9, characterized in that: The Pb-Ag / MnO2 coating anode is composed of a Pb-Ag matrix and a MnO2 coating; Wherein, the crystal phase composition of the MnO2 includes β-MnO2 and γ-MnO2.

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