A method for preparing silver-coated gallium microspheres by electroless plating

Abstract

The application relates to a method for preparing silver-coated gallium microspheres by electroless plating, and belongs to the technical field of composite material preparation. Metal gallium is ultrasonically dispersed in an alcohol solvent to obtain a metal Ga particle suspension, the suspension is left to stand, centrifugal separation is carried out, and excessive alcohol solvent is removed to obtain metal Ga microparticles; the metal Ga microparticles are added into a polyvinylpyrrolidone solution to obtain a metal Ga microsphere suspension; under the conditions of a temperature of 20-50 DEG C, ultrasonic and mechanical stirring, a reducing agent solution and a silver source solution are simultaneously dropped into the metal Ga microsphere suspension to react for 5-30 min, the mixture is left to stand, centrifugal separation is carried out, the obtained product is cleaned with deionized water, and vacuum drying is carried out at a temperature of 40-80 DEG C to obtain silver-coated gallium microspheres. In the application, a reducing agent silver ion is used for in-situ reduction and coating on the surface of gallium microspheres to form a core-shell structure of the silver-coated gallium microspheres. The method is simple in process operation, high in coating uniformity, strong in covering property, easy in process parameter control, and suitable for batch production.

Description

Technical Field

[0001] The invention relates to a method for preparing silver-coated gallium micron beads by chemical plating, belonging to the technical field of composite material preparation. Background Art

[0002] Silver-coated gallium, a novel composite material, has attracted significant attention in electronics, optics, and catalysis due to its unique properties. Silver's excellent electrical conductivity and antibacterial properties, combined with gallium's room-temperature liquid state and chemical stability, make it an ideal base material. Silver-coated gallium combines the high electrical conductivity of silver with the fluidity and chemical stability of gallium, exhibiting excellent catalytic activity and antibacterial properties. It holds great potential for applications in sensors, flexible electronic devices, and optoelectronic devices.

[0003] Silver-coated gallium is prepared by electroless plating, which involves uniformly depositing silver on the gallium surface by controlling reaction conditions such as the reducing agent and reduction temperature. However, the preparation process still faces problems such as difficulty in uniformly coating silver, the gallium surface is easily oxidized, and the coating thickness is difficult to control. Summary of the Invention

[0004] To address the problems of readily oxidized gallium, uneven silver coatings, complex processes, and low efficiency in the existing preparation of silver-coated gallium materials, this paper proposes a method for preparing silver-coated gallium microspheres using an electroless plating process. Specifically, metallic gallium microspheres that have undergone ultrasonic dispersion and surface treatment are added to a polyvinylpyrrolidone (PVP) solution to form a stable Ga suspension. A precisely proportioned reducing agent solution and silver source solution are then slowly added dropwise to the gallium suspension. Under the dual effects of ultrasound and mechanical agitation, silver ions are uniformly deposited on the surface of the gallium particles, forming a complete and dense silver coating. By simultaneously achieving silver ion reduction and uniform coating of gallium particles in a single system, this method significantly improves production efficiency and material performance.

[0005] A method for preparing silver-coated gallium microspheres by chemical plating, the specific steps are as follows:

[0006] (1) ultrasonically dispersing metal gallium in an alcohol solvent to obtain a metal Ga particle suspension, allowing the suspension to stand, and centrifuging to remove excess alcohol solvent to obtain metal Ga micron particles;

[0007] (2) adding metal Ga micron particles to a polyvinyl pyrrolidone solution to obtain a metal Ga micron ball suspension;

[0008] (3) At a temperature of 20 to 50° C., under ultrasonic and mechanical stirring conditions, the reducing agent solution and the silver source solution are simultaneously dropped into the metal Ga micron ball suspension for reaction for 5 to 30 minutes, allowed to stand, centrifuged, washed with deionized water, and vacuum dried at a temperature of 40 to 80° C. to obtain silver-coated gallium micron balls.

[0009] Preferably, the alcohol solvent in step (1) is methanol, ethanol, butanol or isopropanol.

[0010] Preferably, the particle size of the metal Ga micron particles in step (1) is 0.1 to 3 μm.

[0011] Preferably, the concentration of the polyvinyl pyrrolidone solution in step (2) is 5×10 -7 ~5×10 -6 mol / L.

[0012] Preferably, the concentration of metal Ga in the metal Ga microsphere suspension in step (2) is 1 to 10 g / L.

[0013] Preferably, the reducing agent in step (3) is formaldehyde, glucose, hydrazine hydrate, ascorbic acid or tartaric acid, and the silver source is silver nitrate, silver chloride, silver ammonia solution, silver fluoride or silver acetate.

[0014] More preferably, the concentration of the reducing agent solution in step (3) is 0.1 to 0.5 mol / L, and the concentration of the silver source solution is 0.1 to 0.5 mol / L.

[0015] More preferably, the reducing agent solution is added at a rate of 1 to 10 ml / min, and the silver source is added at a rate of 1 to 10 ml / min.

[0016] The mechanism of preparing silver-coated gallium microspheres by the chemical plating method of the present invention: The preparation principle of silver-coated gallium microspheres is based on the chemical plating process of the synergistic action of a reducing agent and a complexing agent. In this process, gallium is used as the core material, and the silver ions are reduced and uniformly deposited on its surface by chemical plating to form a stable silver coating layer. First, the surfactant PVP is used to stabilize the suspension system of the gallium microspheres. It can prevent the agglomeration of gallium microspheres by physical or chemical adsorption on the gallium surface. In addition, the complexing agent can form a stable complex with silver ions (Ag+) through chelation, reduce the free concentration of silver ions in the solution, thereby controlling the release rate of silver ions and avoiding uneven coating caused by excessive deposition. Then, the added reducing agent (such as hydrazine hydrate or ascorbic acid) reduces the silver ions to metallic silver (Ag) under certain conditions. + Under the action of ultrasound and mechanical stirring, Ag gradually deposits on the surface of the Ga spheres, forming a continuous and uniform Ag coating. The concentration and dripping rate of the reducing agent directly affect the deposition rate of silver and the density of the coating. Reasonable control helps to achieve a high-quality coating effect. Through the stabilization of the complexing agent and the action of the reducing agent, silver can be evenly coated on the surface of the gallium spheres, forming a composite material with good conductivity and oxidation resistance. The entire process not only achieves a close combination of silver and gallium, but also effectively avoids the risk of gallium being oxidized during the reaction.

[0017] The beneficial effects of the present invention are:

[0018] (1) The present invention achieves simultaneous silver coating and gallium particle processing in one step: Compared with the traditional method that requires multiple steps to complete the pretreatment of gallium particles and silver coating, the present invention can achieve silver reduction and coating operations in a single reaction system, simplifying the process flow, significantly reducing the preparation steps, and saving time and resources;

[0019] (2) The silver coating layer of the silver-coated gallium microspheres of the present invention has high uniformity and strong coverage: under the synergistic effect of ultrasonic dispersion and mechanical stirring, silver ions can be uniformly deposited on the surface of the gallium particles, ensuring the continuity and density of the silver coating layer, thereby improving the electrical conductivity and antioxidant properties of the material;

[0020] (3) The present invention effectively inhibits gallium surface oxidation: through precise surface treatment and operation in a reducing agent system, the present invention effectively solves the problem of gallium being easily oxidized in air, making the final material more stable and long-lasting;

[0021] (4) The preparation conditions of the silver-coated gallium microspheres of the present invention are controllable and suitable for mass production: by precisely controlling the reducing agent droplet acceleration rate, silver source concentration, and reaction temperature, the present invention achieves effective regulation of the silver coating thickness and particle morphology. The process has good operability, is suitable for large-scale production, and meets industrial requirements;

[0022] (5) The silver-coated gallium microspheres of the present invention have excellent performance: the silver-coated gallium material not only has the high conductivity and antibacterial properties of silver, but also retains the excellent physical and chemical properties of gallium, such as fluidity and conductivity, and thus shows broad application prospects in the fields of electronics, optics, catalysis, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the SEM image of the silver-coated gallium microspheres in Example 1;

[0024] Figure 2 This is the SEM image of the silver-coated gallium microspheres of Example 2;

[0025] Figure 3 This is the SEM image of the silver-coated gallium microspheres of Example 3;

[0026] Figure 4 This is the particle size distribution diagram of silver-coated gallium microspheres in Example 3;

[0027] Figure 5 The SEM image and EDS spectrum of the silver-coated gallium microspheres in Example 4 are shown. DETAILED DESCRIPTION

[0028] The present invention will be further described in detail below in conjunction with specific embodiments, but the protection scope of the present invention is not limited to the contents described above.

[0029] Example 1: A method for preparing silver-coated gallium microspheres by chemical plating, the specific steps are as follows:

[0030] (1) adding metallic gallium to ethanol, ultrasonically dispersing at 30° C. for 1.5 h to obtain a metallic Ga particle suspension, allowing the suspension to stand for 1 h, and centrifuging to remove excess ethanol to obtain metallic Ga micron particles; the particle size of the metallic Ga micron particles is 0.1 to 2 μm;

[0031] (2) Adding metal Ga micron particles to a polyvinyl pyrrolidone solution to obtain a metal Ga micron ball suspension; the concentration of the polyvinyl pyrrolidone solution is 1.5×10 -6 mol / L, the concentration of metal Ga in the suspension of metal Ga microspheres is 1 g / L;

[0032] (3) At a temperature of 30°C, under ultrasonic and mechanical stirring conditions, a reducing agent solution (0.1 mol / L ascorbic acid solution) and a silver source solution (0.25 mol / L silver ammonia solution) were simultaneously added dropwise to the metal Ga microsphere suspension for 15 minutes, allowed to stand, centrifuged, washed with ethanol for more than 3 times, and dried in vacuo at a temperature of 40°C to obtain silver-coated gallium microspheres; the reducing agent solution (ascorbic acid solution) was added at a rate of 2 ml / min, and the silver source solution was added at a rate of 2 ml / min;

[0033] The SEM image of the silver-coated gallium microspheres in this embodiment is shown in FIG. Figure 1 ,from Figure 1 It can be seen that Ag is evenly coated on the outside of the gallium microspheres to form an Ag shell, and the particle size of the silver-coated gallium microspheres is 2 to 3 μm.

[0034] Example 2: A method for preparing silver-coated gallium microspheres by chemical plating, the specific steps are as follows:

[0035] (1) adding metallic gallium to ethanol, ultrasonically dispersing at 50° C. for 1 hour to obtain a metallic Ga particle suspension, allowing the suspension to stand for 2 hours, and centrifuging to remove excess ethanol to obtain metallic Ga micron particles; the particle size of the metallic Ga micron particles is 0.1 to 1 μm;

[0036] (2) Adding metal Ga micron particles to a polyvinyl pyrrolidone solution to obtain a metal Ga micron ball suspension; the concentration of the polyvinyl pyrrolidone solution is 2.0×10 -6 mol / L, the concentration of metal Ga in the metal Ga microsphere suspension is 5 g / L;

[0037] (3) At a temperature of 50°C, under ultrasonic and mechanical stirring conditions, a reducing agent solution (0.2 mol / L ethylene glycol solution) and a silver source solution (0.35 mol / L silver ammonia solution) were simultaneously dripped into the metal Ga micron ball suspension for reaction for 10 minutes, allowed to stand, centrifuged, washed with ethanol for more than 3 times, and vacuum dried at a temperature of 50°C to obtain silver-coated gallium micron balls; the reducing agent solution (formaldehyde solution) was added at a rate of 1 ml / min, and the silver source was added at a rate of 1 ml / min;

[0038] The SEM image of the silver-coated gallium microspheres in this embodiment is shown in FIG. Figure 2 ,from Figure 2 It can be seen that Ag is evenly coated on the outside of the gallium microspheres to form an Ag shell, and the particle size of the silver-coated gallium microspheres is 2 to 3 μm.

[0039] Example 3: A method for preparing silver-coated gallium microspheres by chemical plating, the specific steps are as follows:

[0040] (1) adding metallic gallium to ethanol, ultrasonically dispersing at 60° C. for 1.2 h to obtain a metallic Ga particle suspension, allowing the suspension to stand for 3 h, and centrifuging to remove excess ethanol to obtain metallic Ga micron particles having a particle size of 0.1 to 1.5 μm;

[0041] (2) Adding metal Ga micron particles to a polyvinyl pyrrolidone solution to obtain a metal Ga micron ball suspension; the concentration of the polyvinyl pyrrolidone solution is 2.58×10 -6 mol / L, the concentration of metal Ga in the suspension of metal Ga microspheres is 7 g / L;

[0042] (3) At a temperature of 60°C, under ultrasonic and mechanical stirring conditions, a reducing agent solution (glucose solution with a concentration of 0.2 mol / L) and a silver source solution (0.5 mol / L silver nitrate solution) were simultaneously dripped into the metal Ga micron ball suspension for a reaction of 20 minutes, allowed to stand, centrifuged, washed with ethanol for more than 3 times, and vacuum dried at a temperature of 70°C to obtain silver-coated gallium micron balls; the reducing agent solution (glucose solution) was added at a rate of 5 ml / min, and the silver source was added at a rate of 5 ml / min;

[0043] The SEM image of the silver-coated gallium microspheres in this embodiment is shown in FIG. Figure 3 ,from Figure 3 It can be seen that Ag is evenly coated on the outside of the gallium microspheres to form an Ag shell;

[0044] The laser particle size analyzer test data of the silver-coated gallium powder in this embodiment is shown in Figure 4 The average particle size of the silver-coated gallium microsphere powder is 3 to 6 μm.

[0045] Example 4: A method for preparing silver-coated gallium microspheres by chemical plating, the specific steps are as follows:

[0046] (1) adding metallic gallium to ethanol, ultrasonically dispersing at 40° C. for 1.8 h to obtain a metallic Ga particle suspension, allowing the suspension to stand for 2 h, and centrifuging to remove excess ethanol to obtain metallic Ga micron particles having a particle size of 0.5 to 2 μm;

[0047] (2) Adding metal Ga micron particles to a polyvinyl pyrrolidone solution to obtain a metal Ga micron ball suspension; the concentration of the polyvinyl pyrrolidone solution is 5×10 -7 mol / L, the concentration of metal Ga in the suspension of metal Ga microspheres is 2 g / L;

[0048] (3) At a temperature of 40°C, under ultrasonic and mechanical stirring conditions, a reducing agent solution (a 0.1 mol / L tartaric acid solution) and a silver source solution (a 0.3 mol / L silver acetate solution) were simultaneously added dropwise to a suspension of metallic Ga microspheres for reaction for 30 minutes, allowed to stand, centrifuged, washed with ethanol for more than three times, and dried in a vacuum at a temperature of 65°C to obtain silver-coated gallium microspheres; the reducing agent solution (tartaric acid solution) was added at a rate of 3 ml / min, and the silver source solution was added at a rate of 3 ml / min;

[0049] The SEM image of the silver-coated gallium microspheres in this embodiment is shown in FIG. Figure 5 As can be seen from the figure, Ag is evenly coated on the outside of the gallium microspheres to form an Ag shell; and from the energy spectrum, it can also be seen that the prepared powder is silver-coated gallium powder.

[0050] The above describes the specific embodiments of the present invention in detail, but the present invention is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in this field without departing from the scope of the present invention.

Claims

1. A method for preparing silver-coated gallium microspheres by chemical plating, characterized in that: The specific steps are as follows: (1) Ultrasonic dispersion of metal gallium in an alcohol solvent to obtain a metal Ga particle suspension, allowing the suspension to stand, centrifugation, and removal of excess alcohol solvent to obtain metal Ga micron particles; the alcohol solvent is methanol, ethanol, butanol, or isopropanol; the particle size of the metal Ga micron particles is 0.1 to 3 μm; (2) adding metal Ga micron particles to a polyvinyl pyrrolidone solution to obtain a metal Ga micron ball suspension; the metal Ga concentration in the metal Ga micron ball suspension is 1-10 g / L; (3) At a temperature of 20-50°C, under ultrasonic and mechanical stirring conditions, the reducing agent solution and the silver source solution are simultaneously dripped into the metal Ga micron ball suspension for reaction for 5-30 minutes, allowed to stand, centrifuged, washed with deionized water, and vacuum dried at a temperature of 40-80°C to obtain silver-coated gallium micron balls; the reducing agent is formaldehyde, glucose, hydrazine hydrate, ascorbic acid or tartaric acid, and the silver source is silver nitrate, silver chloride, silver ammonia solution, silver fluoride or silver acetate; the concentration of the reducing agent solution is 0.1-0.5 mol / L, and the concentration of the silver source solution is 0.1-1 mol / L; the dropping speed of the reducing agent solution is 1-10 ml / min, and the dropping speed of the silver source is 1-10 ml / min.

2. The method for preparing silver-coated gallium microspheres by chemical plating according to claim 1, characterized in that: Step (2) The concentration of polyvinyl pyrrolidone solution is 5×10 -7 ~5×10 -6 mol / L.

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