Method for preparing silver-coated gallium micron spheres by chemical plating method

Abstract

The invention relates to a method for preparing silver-coated gallium micron spheres through a chemical plating method, and belongs to the technical field of composite material preparation. The preparation method comprises the following steps: ultrasonically dispersing metal gallium in an alcohol solvent to obtain a metal Ga particle suspension, standing, centrifugally separating, and removing redundant alcohol solvent to obtain metal Ga micron particles; adding the metal Ga micron particles into a polyvinylpyrrolidone solution to obtain a metal Ga micron sphere suspension; and at the temperature of 20-50 DEG C, under the ultrasonic and mechanical stirring conditions, the reducing agent solution and the silver source solution are dropwise added into the metal Ga micron sphere suspension at the same time to react for 5-30 min, standing, centrifugal separation and deionized water cleaning are conducted, vacuum drying is conducted at the temperature of 40-80 DEG C, and the silver-coated gallium micron spheres are obtained. In-situ reduction is carried out by using a reducing agent silver ion, and the surface of the gallium micron sphere is coated with the silver ion to form a core-shell structure of the silver-coated gallium micron sphere. The method disclosed by the invention is simple and convenient in process operation, high in coating uniformity, strong in coverage and suitable for batch production, and process parameters are easy to control.

Description

Technical Field

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

[0002] As a new type of composite material, silver-coated gallium has attracted much attention in the fields of electronics, optics and catalysis due to its unique properties. Silver has good electrical conductivity and antibacterial properties, while gallium is an ideal basic material due to its liquid state at room temperature and chemical stability. Silver-coated gallium materials combine the high conductivity of silver with the fluidity and chemical stability of gallium, showing excellent catalytic activity and antibacterial properties, and have great potential in the fields of sensors, flexible electronic devices and optoelectronic devices.

[0003] The preparation of silver-coated gallium by chemical plating is to uniformly deposit silver on the gallium surface by controlling the reaction conditions such as reducing agent and reduction temperature. However, there are still problems in the preparation process, such as the difficulty of uniform silver coating, the easy oxidation of gallium surface, and the difficulty in controlling the thickness of the coating layer. Summary of the invention

[0004] In view of the problems existing in the preparation process of existing silver-coated gallium materials, such as easy oxidation of gallium, uneven silver coating, complex process and low efficiency, the present invention proposes a method for preparing silver-coated gallium microspheres by chemical plating, that is, adding metal gallium microspheres that have been ultrasonically dispersed and surface-treated to a polyvinyl pyrrolidone (PVP) solution to form a stable Ga suspension, and slowly dropping a reducing agent solution and a silver source solution that have been precisely proportioned into the gallium suspension, and under the dual effects of ultrasound and mechanical stirring, silver ions are uniformly deposited on the surface of gallium particles to form a complete and dense silver coating layer. The present invention greatly improves production efficiency and material performance by simultaneously realizing the reduction of silver ions and the uniform coating of gallium particles in a single system.

[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, centrifuging, and removing excess alcohol solvent to obtain metal Ga micron particles;

[0007] (2) adding metal Ga micron particles into 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 microsphere suspension to react for 5 to 30 minutes, the suspension is allowed to stand, centrifuged, washed with deionized water, and vacuum dried at a temperature of 40 to 80° C. to obtain silver-coated gallium microspheres.

[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 0.1-0.5 mol / L, and the concentration of the silver source solution is 0.1-0.5 / L.

[0015] More preferably, the dropping speed of the reducing agent solution is 1 to 10 ml / min, and the dropping speed of the silver source is 1 to 10 ml / min.

[0016] The mechanism of preparing silver-coated gallium microspheres by 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 reducing agent and 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 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 too fast 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 to form a continuous and uniform Ag coating layer. The concentration and drop rate of the reducing agent directly affect the deposition rate of silver and the compactness of the coating layer. Reasonable control helps to achieve high-quality coating effects. Through the stabilization of the complexing agent and the action of the reducing agent, silver can be evenly covered on the surface of the gallium spheres to form a composite material with good conductivity and oxidation resistance. The whole 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 realizes 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 realize silver reduction and coating operations in one reaction system, which simplifies the process flow, greatly reduces the preparation steps, and saves 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 gallium particles, ensuring the continuity and density of the silver coating layer, thereby improving the conductivity and antioxidant properties of the material;

[0020] (3) The present invention achieves effective inhibition of 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 the 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 drop rate, silver source concentration and reaction temperature, the present invention achieves effective regulation of the thickness of the silver coating layer and the particle morphology. The process has good operability, is suitable for large-scale production, and meets industrialization needs;

[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 of 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 of Example 4 are shown. DETAILED DESCRIPTION

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

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

[0030] (1) adding metal gallium to ethanol, ultrasonically dispersing for 1.5 hours at a temperature of 30° C. to obtain a metal Ga particle suspension, standing for 1 hour, centrifuging, removing excess ethanol, and obtaining metal Ga micron particles; the particle size of the metal Ga micron particles is 0.1 to 2 μm;

[0031] (2) Adding metal Ga micron particles into 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) under the conditions of temperature of 30° C., ultrasound and mechanical stirring, 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 dripped into the metal Ga micron ball suspension to react for 15 min, allowed to stand, centrifuged, washed with ethanol for more than 3 times, and dried under vacuum at a temperature of 40° C. to obtain silver-coated gallium micron balls; the dropping speed of the reducing agent solution (ascorbic acid solution) was 2 ml / min, and the dropping speed of the silver source was 2 ml / min;

[0033] The SEM image of the silver-coated gallium microspheres in this embodiment is shown in Figure 1 ,from Figure 1 It can be seen that Ag is uniformly 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 metal gallium to ethanol, ultrasonically dispersing at 50° C. for 1 h to obtain a metal Ga particle suspension, standing for 2 h, centrifuging, removing excess ethanol, and obtaining metal Ga micron particles; the particle size of the metal Ga micron particles is 0.1 to 1 μm;

[0036] (2) Adding metal Ga micron particles into 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) under the conditions of 50° C., ultrasound and mechanical stirring, 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 microsphere suspension to react for 10 min, allowed to stand, centrifuged, washed with ethanol for more than 3 times, and dried in vacuum at 50° C. to obtain silver-coated gallium microspheres; 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 Figure 2 ,from Figure 2 It can be seen that Ag is uniformly 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 metal gallium to ethanol, dispersing by ultrasonic method at 60° C. for 1.2 h to obtain a metal Ga particle suspension, standing for 3 h, centrifuging, removing excess ethanol, and obtaining metal Ga micron particles; the particle size of the metal Ga micron particles is 0.1 to 1.5 μm;

[0041] (2) Adding metal Ga micron particles into 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 metal Ga microsphere suspension is 7g / L;

[0042] (3) under the conditions of 60° C., ultrasound and mechanical stirring, 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) are simultaneously dripped into the metal Ga microsphere suspension to react for 20 min, the suspension is allowed to stand, centrifuged, washed with ethanol for more than 3 times, and vacuum dried at 70° C. to obtain silver-coated gallium microspheres; the dropping speed of the reducing agent solution (glucose solution) is 5 ml / min, and the dropping speed of the silver source is 5 ml / min;

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

[0044] The laser particle size analyzer test data of silver-coated gallium powder in this example 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 metal gallium to ethanol, dispersing by ultrasonic at 40° C. for 1.8 h to obtain a metal Ga particle suspension, standing for 2 h, centrifuging, removing excess ethanol, and obtaining metal Ga micron particles; the particle size of the metal Ga micron particles is 0.5 to 2 μm;

[0047] (2) Adding metal Ga micron particles into 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 metal Ga microsphere suspension is 2 g / L;

[0048] (3) under the conditions of 40° C., ultrasound and mechanical stirring, a reducing agent solution (0.1 mol / L tartaric acid solution) and a silver source solution (0.3 mol / L silver acetate solution) were simultaneously dripped into the metal Ga microsphere suspension to react for 30 min, allowed to stand, centrifuged, washed with ethanol for more than 3 times, and dried under vacuum at 65° C. to obtain silver-coated gallium microspheres; the dropping speed of the reducing agent solution (tartaric acid solution) was 3 ml / min, and the dropping speed of the silver source was 3 ml / min;

[0049] The SEM image of the silver-coated gallium microspheres in this embodiment is shown in Figure 5 As can be seen from the figure, Ag is uniformly coated on the outside of the gallium microsphere 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 specific implementation modes of the present invention are described in detail above, but the present invention is not limited to the above implementation modes, and various changes can be made within the knowledge scope of ordinary technicians in this field without departing from the purpose 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) ultrasonically dispersing metal gallium in an alcohol solvent to obtain a metal Ga particle suspension, allowing the suspension to stand, centrifuging, and removing excess alcohol solvent to obtain metal Ga micron particles; (2) adding metal Ga micron particles into a polyvinyl pyrrolidone solution to obtain a metal Ga micron ball suspension; (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 microsphere suspension to react for 5 to 30 minutes, the suspension is allowed to stand, centrifuged, washed with deionized water, and vacuum dried at a temperature of 40 to 80° C. to obtain silver-coated gallium microspheres.

2. The method for preparing silver-coated gallium microspheres by chemical plating according to claim 1, characterized in that: The alcohol solvent in step (1) is methanol, ethanol, butanol or isopropanol.

3. The method for preparing silver-coated gallium microspheres by chemical plating according to claim 1, characterized in that: Step (1) The particle size of the metal Ga micron particles is 0.1 to 3 μm.

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

5. The method for preparing silver-coated gallium microspheres by chemical plating according to claim 1, characterized in that: The concentration of metal Ga in the metal Ga microsphere suspension in step (2) is 1 to 10 g / L.

6. The method for preparing silver-coated gallium microspheres by chemical plating according to claim 1, characterized in that: 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.

7. The method for preparing silver-coated gallium microspheres by chemical plating according to claim 1 or 6, characterized in that: The concentration of the reducing agent solution in step (3) is 0.1-0.5 mol / L, and the concentration of the silver source solution is 0.1-1 mol / L.

8. The method for preparing silver-coated gallium microspheres by chemical plating according to claim 7, characterized in that: The dropping speed of the reducing agent solution is 1 to 10 ml / min, and the dropping speed of the silver source is 1 to 10 ml / min.

Images