CN115247273A - Method for electrodepositing silver - Google Patents

Abstract

The present invention relates to the technical field of electrodeposition, in particular to a method for electrodepositing silver. The method for electrodepositing silver includes: placing a substrate in an electrolyte, and performing electrodeposition by a potentiostatic method to obtain a silver coating; wherein, the electrolyte includes a eutectic ionic liquid, an additive and a silver source; the additive Including at least one of chloride salts, nitrogen-containing heterocyclic compounds and amine compounds. The method for electrodepositing silver provided by the present invention can significantly improve the quality of the prepared silver coating by using a specific electrolyte, especially adding specific additives, so that the color of the prepared silver coating is silvery white without yellowing , the thickness is suitable, and at the same time, it can enhance the bonding force of the coating and its anti-discoloration ability.

Description

A method of electrodepositing silver

technical field

The invention relates to the technical field of electrodeposition, in particular to a method for electrodepositing silver.

Background technique

Due to its excellent corrosion resistance, lubricity, decoration, antibacterial properties, high conductivity, high catalytic performance, and high sensitivity to the environment, silver metal is widely used in the microelectronics industry, catalyst field, sensor field, and the preparation of magnetic materials. The field of resistive materials has been widely used.

Due to its unique physical and chemical properties and broad application prospects, nanomaterials have become a research hotspot. Among them, as an important functional material, nano-silver has been widely used in many fields such as ceramic materials, environmental protection materials and coatings. The synthesis methods of nano-silver include chemical reduction method, ultrasonic method, photoreduction method and electrochemical reduction method. The electrodeposition method is applicable to many nanocrystalline materials, and the electrodeposition method can be used to prepare rapidly, and the prepared nanocrystalline materials have stable properties. Among them, the choice of electrolyte plays a crucial role.

With the improvement of people's awareness of environmental protection and the concept of green chemistry, novel ionic liquids (ILs) electrolytes have attracted great attention. Ionic liquid is a molten salt system composed of specific organic positive ions and inorganic negative ions that is liquid at room temperature or near room temperature. It is a new type of medium and "soft" functional material. Because of its low melting point, wide electrochemical window, high stability, selective solvency and designability, it is used for the deposition of copper, zinc, chromium, silver and other metals and alloys.

In recent years, deep eutectic ionic liquids (also known as deep eutectic solvents, DESs) have become a green alternative to traditional ILs and aqueous solutions due to their unique advantages such as non-toxicity, low cost, and high purity. The most common eutectic ionic liquid is based on a mixture of urea and choline chloride, has a freezing point of 12°C and remains liquid at room temperature. The greenness and sustainability of this new solvent lies in the fact that both of its components are cheap, biodegradable, non-toxic, and widely available in nature. They can be easily mixed to form high-purity solvents without requiring expensive labor and equipment.

The electrolyte composition of the conventional aqueous solution system is complex, and additives such as brighteners, main complexing agents, auxiliary complexing agents, and leveling agents need to be added. However, these organic additives will make the composition of the solution more complicated, causing the solution to be unstable, making it difficult to recycle and process the plating solution, and polluting the environment.

However, the silver coating obtained by conventional eutectic ionic liquid deposition often has problems such as yellowish color, poor bonding force, and poor discoloration resistance, which cannot meet the requirements of the process.

In view of this, the present invention is proposed.

SUMMARY OF THE INVENTION

The first object of the present invention is to provide a method for electrodepositing silver. By adding specific additives to the electrolyte, the quality of the obtained silver coating can be significantly improved, and the color of the obtained silver coating can be silvery-white without tingling. Yellow, the thickness is appropriate, and at the same time, it can enhance the bonding force of the coating and its ability to resist discoloration.

In order to realize the above-mentioned purpose of the present invention, special adopt following technical scheme:

The invention provides a method for electrodepositing silver, comprising the steps of:

The substrate is placed in the electrolyte, and the constant potential method is used for electrodeposition to obtain a silver coating;

Wherein, the electrolyte includes a deep eutectic ionic liquid, an additive and a silver source;

The additives include at least one of chlorine salts, nitrogen-containing heterocyclic compounds and amine compounds.

In some specific embodiments of the present invention, the additive can be selected from one of chlorine salts, nitrogen-containing heterocyclic compounds and amine compounds, or a mixture of any of the above types.

The present invention significantly improves the quality of the prepared silver coating by using a specific electrolyte, especially adding a specific additive, and the color of the prepared silver coating is silvery white without yellowing, and the thickness is suitable; and, Significantly enhance the bonding force between the coating and the substrate, as well as the anti-tarnish ability of the silver coating.

At the same time, the electrolyte provided by the present invention can be reused, and recycling can not only save costs and avoid waste of resources, but also solve the problem of complex components, difficult recycling, and difficult processing of the conventional aqueous solution system electrolyte in the prior art. And other issues.

Specifically, the present invention adds specific additives by using a specific electrolyte, thereby improving the quality of the silver coating, enhancing the bonding force between the coating and the substrate and the mechanism of the anti-tarnish ability of the coating as follows:

Add specific additives to make silver ions exist in the form of complexes in the plating solution, so that they can show greater electrochemical polarization during deposition. The magnitude of the electrochemical polarization is related to the energy change when the ligands around the central ion transform. The energy of silver complex ions mainly present in the electrolyte changes greatly when they are converted into activated complexes, and the activation energy required for reduction is relatively high, resulting in increased electrochemical polarization, and the quality of the obtained coating is good. In addition, a coordination reaction occurs between the additive adsorbed on the surface of the cathode and the silver complex ions in the solution, forming a surface complex on the metal surface. The formation of the surface complex makes the discharge of metal ions more difficult, and the overvoltage of the reaction is also significantly increased. , which is conducive to the formation of new crystal nuclei, and as a result, the precipitated silver grains are relatively small.

In addition, the present invention can obtain silver coatings with different crystal nucleus sizes and different deposition effects by adding different types and amounts of additives. Specifically, since Ag ⁺ has a full d ¹⁰ electron configuration, it forms all valence type (or outer orbital) complexes, and the lone pair of electrons of the ligand can only enter the outer orbital of Ag ⁺ , so it Both are active in electron substitution reactions. In the electrode reaction kinetics, the electrode reduction reaction is faster, and the electrode reaction rate constant value is also the highest (≥10 ^-1 s ^-1 ) among metal ions. In order to greatly reduce the electrode reaction rate of Ag ⁺ , the present invention adds additives and Silver ions form complexes to control the growth rate and direction of crystal nuclei, thereby obtaining silver coatings with different crystal nucleus sizes and different deposition effects.

Preferably, the deep eutectic ionic liquid comprises a mixture of choline chloride and urea, 1-ethyl-3-methylimidazolium tetrafluoroborate and 1-ethyl-3-methylimidazolium hexafluorophosphate at least one of the

Deep eutectic ionic liquid, also known as deep eutectic solvent, refers to a two-component or three-component eutectic mixture composed of hydrogen bond acceptors and hydrogen bond donors in a certain stoichiometric ratio, and its freezing point is significantly lower The melting point of the pure substance of each component.

Using deep eutectic ionic liquids as solvents has the advantages of non-toxicity, low cost, easy preparation and biodegradability.

Preferably, the chloride salt comprises ammonium chloride and/or potassium chloride.

The chlorine salt refers to a general term for salts in which the anion is a chloride ion.

The present invention forms [AgCl ₂ ] ^-1 complexes by adding chlorine salts and silver ions, and can control the growth speed and direction of crystal nuclei, thereby obtaining silver coatings with different crystal nuclei sizes.

And/or, the nitrogen-containing heterocyclic compound includes at least one of 5,5-dimethylhydantoin, hydantoin and 5-methylhydantoin.

Here, the nitrogen-containing heterocyclic compound refers to a heterocyclic compound containing a nitrogen atom. Heterocyclic compound is an organic compound containing a heterocyclic structure in the molecule. The atoms constituting the ring contain at least one heteroatom in addition to carbon atoms. It is the largest number of organic compounds, and the most common heteroatoms are nitrogen atoms, sulfur atom, oxygen atom.

5,5-Dimethylhydantoin, the chemical formula is C ₅ H ₈ N ₂ O ₂ , also known as dimethylhydantoin, 5,5-dimethylimidazolidinedione and DMH. It is mainly used as a raw material for bactericidal disinfectants, epoxy resins and amino acids.

Hydantoin is an organic compound with a molecular formula of C ₃ H ₄ N ₂ O ₂ . It is mainly used in chemical, pharmaceutical, textile, biochemical and other fields. It is also known as hydantoin and 2,4-imidazolidinedione.

5-Methylhydantoin is a chemical substance with the molecular formula C ₄ H ₆ N ₂ O ₂ . Also known as 5-methylhydantoin.

And/or, the amine compound includes ethylenediamine and/or ethylenediaminetetraacetic acid.

Among them, ethylenediamine, referred to as EDA, has a chemical formula of C ₂ H ₈ N ₂ , is a typical aliphatic diamine, and is a colorless or light yellow oily or watery transparent liquid.

Ethylenediaminetetraacetic acid (EDTA) is a derivative of aliphatic diamine, its chemical formula is C ₁₀ H ₁₆ N ₂ O ₈ , and it is a white powder at normal temperature and pressure.

The applicant unexpectedly found that the concentration of ammonium chloride will affect the performance of the coating. When the concentration of ammonium chloride is within a specific range, the performance of the coating is better, but at this time the bonding force between the coating and the substrate is poor.

Therefore, the present invention can improve the binding force between the coating and the substrate while ensuring the color and discoloration resistance of the coating by using specific additives, that is, specific types of nitrogen-containing heterocyclic compounds and amine compounds. It does not peel off and is not prone to peeling or bubbling.

Preferably, the silver source comprises silver nitrate and/or silver chloride.

With silver nitrate as the silver source, the ionized silver ions and silver ions form [AgCl ₂ ] ^-1 complexes.

Using silver chloride as the silver source, silver chloride is insoluble in aqueous solution, but it can be well dissolved into Ag ⁺ and Cl ^- in the ionic liquid system by heating and stirring.

Preferably, in the electrolyte, the molar concentration of the additive is 0.1-0.6 mol/L.

In this application, the concentration of the additive will affect the growth rate and direction of the crystal nucleus, which can affect the deposition effect, such as changing the quality of the silver coating (including color and silver size), the bonding force of the coating to the substrate, and the anti-tarnish of the coating ability.

Adopting the molar concentration in the above-mentioned range is beneficial to obtain a silver coating with better performance.

Preferably, the potential used in the constant potential method is -1.0 to -0.7V, including but not limited to the point value of any one of -0.95V, -0.9V, -0.85V, -0.8V, -0.75V or any range value in between.

The deposition potential can also affect the growth rate and direction of crystal nuclei, thereby changing the electrodeposition effect.

Adopting the potential in the above range is beneficial to further improve the performance of the silver coating.

Preferably, the electrodeposition time is 20-60 minutes; including but not limited to a point value of any one of 25 minutes, 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes, and 55 minutes or a range value between any two.

Preferably, during the electrodeposition process, the temperature of the electrolyte is 40-60°C, including but not limited to 42°C, 45°C, 48°C, 50°C, 53°C, 56°C, 59°C Either a point value or any range value in between.

The time of electrodeposition, as well as the temperature of the electrolyte during the electrodeposition process, have a certain influence on the electrodeposition effect. The performance of the silver plating can be further improved by using the above-mentioned electrodeposition time and the temperature of the electrolyte.

In addition, the method for electrodepositing silver provided by the present invention has low electrolyte temperature and low energy consumption, which is beneficial to energy saving and cost reduction.

Preferably, said substrate comprises copper alloy and/or carbon steel;

Preferably, the copper alloy includes brass and/or copper.

The type of substrate has a great influence on the effect of electrodeposition, especially the bonding force between the coating and the substrate. The use of the above-mentioned type of substrate is beneficial to enhance the bonding force between the coating and the substrate.

Preferably, in the process of electrodeposition, a three-electrode system is used;

In the three-electrode system, the substrate is used as the working electrode, the Ag/AgCl electrode is used as the reference electrode, and the platinum electrode is used as the auxiliary electrode.

The three electrodes refer to the working electrode, the reference electrode and the auxiliary electrode. The use of the three electrode system can control the potential difference more accurately and reduce the error.

Preferably, the average particle size D50 of silver in the silver plating layer is 0.1-2.5 μm, including but not limited to 0.2 μm, 0.3 μm, 0.4 μm, 0.5 μm, 0.8 μm, 1.0 μm, 1.3 μm, 1.6 μm, 1.9 μm A point value of any one of μm, 2 μm, 2.2 μm, and 2.4 μm or a range value between any two.

By changing various parameters in the electrodeposition process, especially the type and amount of additives, and the deposition potential, the growth rate and direction of crystal nuclei can be controlled, thereby obtaining silver coatings with different crystal nucleus sizes.

In some specific embodiments of the present invention, the silver coating prepared in the present invention is micro-nano silver particles in the form of microspheres.

In some specific embodiments of the present invention, the preparation method of the electrolyte comprises: after uniformly mixing choline chloride and urea, adding silver sources and additives therein in sequence;

Preferably, in the process of uniformly mixing choline chloride and urea, the temperature of the mixed material is 70-90°C; including but not limited to 72°C, 75°C, 77°C, 80°C, 85°C, 88°C A point value of either or a range value in between.

Preferably, the choline chloride and the urea are uniformly mixed by stirring.

More preferably, the stirring speed is 400-600r/min, including but not limited to a point value of any one of 450r/min, 500r/min, and 550r/min or a range value between any two.

More preferably, the stirring time is 2 to 5 hours, including but not limited to a point value of any one of 2.5 hours, 3 hours, 3.5 hours, 4 hours and 4.5 hours or a range value between any two.

Preferably, in the mixture of the choline chloride and urea, the molar ratio of the choline chloride to the urea is 1:1～5 (1:2, 1:3 or 1:4 can also be selected ); more preferably 1:2.

In some specific embodiments of the present invention, the substrate is pretreated, and the pretreatment specifically includes: polishing, washing and activating the substrate in sequence.

Preferably, the grinding specifically includes: sequentially grinding with sandpaper with mesh numbers of 240 mesh, 400 mesh, 1200 mesh and 2000 mesh;

Preferably, water is used for the washing; more preferably, the water comprises deionized water;

Preferably, the activation solution used in the activation is an acid solution;

Preferably, the acid solution includes dilute hydrochloric acid and/or dilute sulfuric acid;

Preferably, the activation time is 20-60s, including but not limited to a point value of any one of 25s, 30s, 35s, 40s, 45s, 50s, 55s or a range value between any two.

In some specific embodiments of the present invention, after the activation, the following steps are further included: ultrasonically treating the activated working electrode, and then washing with water;

Preferably, the frequency of the ultrasonic wave is 20-40kHz, including but not limited to a point value of any one of 25kHz, 30kHz, 35kHz, and 38kHz or a range value between any two.

Preferably, the ultrasonic treatment time is 5-30 minutes, including but not limited to a point value of any one of 10 minutes, 15 minutes, 20 minutes, and 25 minutes or a range value between any two.

By pretreating the substrate, impurities on the surface of the substrate can be removed to make the surface smooth, uniform and clean.

Compared with prior art, the beneficial effect of the present invention is:

(1) The method for electrodepositing silver provided by the present invention can significantly improve the quality of the obtained silver coating by using an electrolyte of a specific composition, especially adding a specific type of additive, and the color of the prepared silver coating is silvery white , the thickness is appropriate, and it can also enhance the bonding force between the coating and the substrate, and enhance the anti-tarnish ability of the silver coating.

(2) In the method for electrodepositing silver provided by the present invention, by changing the type and amount of additives, silver coatings with different crystal nucleus sizes can be obtained and the deposition effect can be changed.

(3) The method for electrodepositing silver provided by the present invention can change the deposition effect by changing the deposition potential used in the constant potential method.

(4) The method for electrodepositing silver provided by the present invention, wherein the electrolyte has the advantages of non-toxicity, low cost, easy preparation and biodegradability, and can be recycled, saving the preparation cost and processing cost, avoiding the Waste of resources.

Description of drawings

In order to more clearly illustrate the specific implementation of the present invention or the technical solutions in the prior art, the following will briefly introduce the accompanying drawings that need to be used in the specific implementation or description of the prior art. Obviously, the accompanying drawings in the following description The drawings show some implementations of the present invention, and those skilled in the art can obtain other drawings based on these drawings without any creative work.

Fig. 1 is the XRD figure of the silver coating that embodiment 1 provided by the present invention makes;

Fig. 2 is the EDX figure of the silver coating that embodiment 1 provided by the present invention makes;

Fig. 3 is the SEM figure of the silver coating that embodiment 1 provided by the present invention makes;

Fig. 4 is the XRD figure of the silver coating that Comparative Example 1 made by the present invention;

Fig. 5 is the EDX figure of the silver coating that comparative example 1 makes provided by the present invention;

Fig. 6 is the SEM image of the silver coating prepared in Comparative Example 1 provided by the present invention.

Detailed ways

The technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and specific embodiments, but those skilled in the art will understand that the embodiments described below are some of the embodiments of the present invention, rather than all of them. It is only used to illustrate the present invention and should not be construed as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention. Those who do not indicate the specific conditions in the examples are carried out according to the conventional conditions or the conditions suggested by the manufacturer. The reagents or instruments used were not indicated by the manufacturer, and they were all conventional products that could be purchased from the market.

Example 1

The method for electrodepositing silver provided by the present embodiment comprises the following steps:

(1) 13.9g of choline chloride and 12g of urea (the molar ratio of choline chloride and urea is 1:2) are placed in a beaker and mixed evenly, then placed in a 70°C oil bath, stirring constantly ( The rotating speed of stirring is 500r/min) to transparent clarification, obtain deep eutectic ionic liquid; Then add 0.82g silver nitrate and 0.4gNH ₄ Cl to it successively, after stirring evenly, obtain electrolytic solution (the mole of NH ₄ Cl in electrolytic solution Concentration is 0.3mol/L);

(2) The brass substrate is polished and polished with 240 mesh, 400 mesh, 1200 mesh, and 2000 mesh sandpaper in sequence, and after being cleaned with deionized water, it is placed in a mixture of dilute hydrochloric acid and dilute sulfuric acid at room temperature Activation for 30s; then ultrasonic cleaning at room temperature for 10min (the frequency of the ultrasonic wave is 28kHz), and then cleaning with deionized water to obtain a pretreated brass substrate;

(3) A three-electrode system is adopted, with the pretreated brass substrate obtained in step (2) as the working electrode, the Ag/AgCl electrode as the reference electrode, and the platinum electrode as the auxiliary electrode; The potential is -0.8V, the temperature of the electrolyte during the deposition process is 50°C, and the deposition time is 30 minutes; after the deposition is completed, a silver coating is obtained on the surface of the substrate.

Example 2

The method for electrodepositing silver provided in this example is basically the same as Example 1, the only difference is that in step (1), the amount of NH ₄ Cl added is replaced by 0.82g, that is, the molar concentration of NH ₄ Cl in the electrolyte is 0.6mol/L.

Example 3

The method for electrodepositing silver provided in this example is basically the same as Example 1, the only difference is that in step (1), the amount of NH ₄ Cl added is replaced by 0.13g, that is, the molar concentration of NH ₄ Cl in the electrolyte is 0.1mol/L.

Example 4

The silver electrodeposition method provided in this example is basically the same as that in Example 1, except that in step (1), the additive NH ₄ Cl is replaced by DMH (the molar concentration of DMH in the electrolyte is 0.8 mol/L).

Example 5

The silver electrodeposition method provided in this example is basically the same as that in Example 1, except that in step (1), the additive NH ₄ Cl is replaced by EDTA (the molar concentration of EDTA in the electrolyte is 0.075 mol/L).

Example 6

The method for electrodepositing silver provided in this example is basically the same as that in Example 1, except that in step (1), 0.4g of NH ₄ Cl is replaced by a mixture of 2.56g of DMH and 0.18g of EDTA.

Example 7

The method of electrodepositing silver provided in the example is basically the same as that in Example 1, except that in step (1), 0.4g of NH ₄ Cl is replaced by a mixture of 1.96g of hydantoin and 0.037g of ethylenediamine.

Comparative Example 1

The silver electrodeposition method provided in this comparative example is basically the same as that in Example 1, the only difference being that in step (1), NH ₄ Cl is not added.

Comparative Example 2

The method for electrodepositing silver provided in this comparative example is basically the same as that in Example 6, except that in step (3), the deposition potential is replaced with -0.6V.

Comparative Example 3

The method for electrodepositing silver provided in this comparative example is basically the same as that in Example 6, except that in step (3), the deposition potential is replaced with -1.5V.

Comparative Example 4

The method for electrodepositing silver provided in this comparative example is basically the same as that in Example 6, except that in step (2), the substrate is replaced by a nickel sheet.

Experimental example 1

The silver coating prepared in Example 1 was tested by XRD, EDX and SEM, and the results are shown in Figure 1, Figure 2 and Figure 3 respectively. Wherein, Fig. 1 is the XRD figure (instance 1 of marking among Fig. 1 being embodiment 1) of the silver coating that the embodiment 1 that the present invention makes; Fig. 2 is the silver coating that the embodiment 1 that the present invention makes EDX figure (instance 1 of marking in Fig. 2 is embodiment 1); Fig. 3 is the SEM figure of the silver coating that embodiment 1 that the present invention makes.

As can be seen from Fig. 1, Fig. 2 and Fig. 3, the embodiment of the present invention 1 has obtained microspherical silver particles after electrodeposition, and XRD result shows, and coating is made up of pure silver, and trace _AgO is because trace water reduction and caused by the decomposition of AgOH. EDX results show that the mass percentage of silver accounts for 97%. It can be seen that, in Example 1 of the present invention, a microspherical and high-purity silver coating was prepared.

The silver coating prepared in Comparative Example 1 was tested by XRD, EDX and SEM, and the results are shown in Figure 4, Figure 5 and Figure 6 respectively. Wherein, Fig. 4 is the XRD figure of the silver coating that the comparative example 1 that the present invention makes; Fig. 5 is the EDX figure that the silver coating that the comparative example 1 makes is provided by the present invention; Fig. 6 is the comparative example 1 that the present invention provides SEM image of the as-prepared silver coating.

It can be seen from Fig. 4, Fig. 5 and Fig. 6 that dendritic silver was obtained by electrodeposition in Comparative Example 1. Due to the dispersed structure of dendrite silver, the bonding force of the coating is deteriorated and the coating is uneven. Meanwhile, the XRD result of Comparative Example 1 shows that the plating layer is composed of pure silver; the EDX result shows that the mass percentage of silver accounts for 84% due to the thinner plating layer. It can be seen that the silver coating obtained in Comparative Example 1 not only has lower purity, but also is dendritic.

Experimental example 2

The appearance (comprising color and thickness), anti-tarnish ability of the silver coating that above each embodiment and comparative example make, and the binding force of coating and substrate are detected and counted, and the results are shown in table 1 respectively.

The appearance of each group of silver plating of table 1, the test result of resistance to discoloration and binding force

By comparing Example 1 and Comparative Example 1 in Table 1, it can be found that the addition of ammonium chloride increases the thickness of the coating and enhances the ability to resist discoloration. By contrasting Example 1, Example 2 and Example 3, it can be seen that the concentration of ammonium chloride will have an impact on the performance of the coating, and when the concentration of ammonium chloride is 0.3mol/L, the coating performance is the best, but the coating and substrate The binding force is poor.

However, in Example 4, Example 5, Example 6 and Example 7, after changing the types of additives, the bonding force between the coating and the substrate is improved to a certain extent, and the performance of the coating is improved. Especially in Example 6, with DMH as the main complexing agent and EDTA as the auxiliary complexing agent, the performance of the coating can be improved to the greatest extent.

And by comparing Example 6 with Comparative Example 2, Comparative Example 3, and Comparative Example 4, it can be found that no matter whether it is high potential or low potential, the coating performance will be reduced, and when the nickel sheet is used as the deposition substrate, there is no obvious coating. It can be seen that both the deposition potential and the type of substrate have an impact on the performance of the coating. However, the use of the deposition potential and substrate provided by the present invention is beneficial to further improving the performance of the coating.

Although the present invention has been illustrated and described with specific embodiments, it should be appreciated that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them; those of ordinary skill in the art should understand that: In the case of departing from the spirit and scope of the present invention, the technical solutions recorded in the foregoing embodiments may be modified, or some or all of the technical features thereof may be equivalently replaced; and these modifications or replacements do not make the corresponding technical solutions Essentially departing from the scope of the technical solutions of the various embodiments of the present invention; therefore, it is intended to include in the appended claims all such replacements and modifications that fall within the scope of the present invention.

Claims (10)

1. a method for electrodepositing silver, is characterized in that, comprises the steps: The substrate is placed in the electrolyte, and the constant potential method is used for electrodeposition to obtain a silver coating; Wherein, the electrolyte includes a deep eutectic ionic liquid, an additive and a silver source; The additives include at least one of chlorine salts, nitrogen-containing heterocyclic compounds and amine compounds. 2. the method for electrodeposition silver according to claim 1, is characterized in that, described eutectic ionic liquid comprises the mixture of choline chloride and urea, 1-ethyl-3-methylimidazolium tetrafluoroboric acid salt and at least one of 1-ethyl-3-methylimidazolium hexafluorophosphate. 3. the method for electrodeposition silver according to claim 1, is characterized in that, described chloride salt comprises ammonium chloride and/or Repone K; And/or, the nitrogen-containing heterocyclic compound includes at least one of 5,5-dimethylhydantoin, hydantoin and 5-methylhydantoin; And/or, the amine compound includes ethylenediamine and/or ethylenediaminetetraacetic acid. 4. The method for electrodepositing silver according to claim 1, wherein the silver source comprises silver nitrate and/or silver chloride. 5. The method for electrodepositing silver according to claim 1, characterized in that, in the electrolyte, the molar concentration of the additive is 0.1-0.6 mol/L. 6. The method for electrodepositing silver according to any one of claims 1-5, characterized in that the potential used in the constant potential method is -1.0-0.7V. 7. The method for electrodepositing silver according to any one of claims 1 to 5, wherein the electrodeposition time is 20 to 60 minutes; Preferably, during the electrodeposition process, the temperature of the electrolyte is 40-60°C. 8. The method for electrodepositing silver according to any one of claims 1 to 5, wherein the substrate comprises copper alloy and/or carbon steel; Preferably, the copper alloy includes brass and/or copper. 9. The method for electrodepositing silver according to any one of claims 1 to 5, characterized in that, in the process of electrodeposition, a three-electrode system is used; In the three-electrode system, the substrate is used as the working electrode, the Ag/AgCl electrode is used as the reference electrode, and the platinum electrode is used as the auxiliary electrode. 10. The method for electrodepositing silver according to any one of claims 1-5, characterized in that, the average particle size D50 of silver in the silver plating layer is 0.1-2.5 μm.

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