Method for preparing ultrafine silver-copper nanoparticles by reactive liquid phase laser ablation

Abstract

The present invention discloses a method for preparing ultrafine silver-copper nanoparticles by reactive liquid phase laser ablation. The method first places a pure copper target material in a pretreatment liquid for pretreatment, and then places it in a liquid phase formed by the pretreatment liquid to which a surfactant is added, and focuses a pulsed laser beam on the contact surface between the target material and the liquid phase to generate ultrafine silver-copper nanoparticles by ablation reaction. The silver-copper nanoparticles prepared by the method of the present invention have a small particle size, a narrow size distribution, and good monodispersity. The silver and copper elements inside are evenly distributed and the copper element is basically not oxidized. The preparation of ultrafine silver-copper nanoparticles can be achieved under normal temperature and pressure.

Description

Technical Field

[0001] The invention belongs to the technical field of nano material preparation, and relates to a method for preparing ultrafine silver-copper nanoparticles by reactive liquid phase laser ablation. Background Art

[0002] Alloy nanoparticles have unique physical and chemical properties and are widely used in magnetism, optics, plasma, biology, analytical chemistry, catalysis and other fields. The research on alloy nanoparticles, especially the preparation and application of alloy nanoparticles with adjustable composition and high composition uniformity, has always been the research focus in the field of nanoalloys.

[0003] Silver and copper nanoalloys have become promising materials due to their high conductivity and better adhesion properties. They are widely used in antibacterial and conductive inks, optical fiber sensors, catalysts, heat transfer, and solar cells. However, the spontaneous oxidation of copper and the relatively high price of silver limit the application of silver and copper nanoalloys. The emergence of silver-copper alloy nanoparticles is expected to solve this dilemma. However, there is still a lack of simple and environmentally friendly synthesis methods for Ag-Cu nanostructured materials.

[0004] Liquid phase laser ablation is a method for preparing ultrafine alloy nanoparticles with adjustable composition and high composition uniformity. However, this method will inevitably produce oxidation when preparing nanoparticles of easily oxidizable elements. Miranda et al. used liquid phase laser ablation to obtain copper oxide particles and cuprous oxide in aqueous solution. The oxygen dissolved in water will lead to the formation of an oxide layer (Characterization of Copper nanoparticles obtained by laser ablation in liquids [J], Appl. Phys. A, 2013, 110: 829–833). Malviya et al. prepared silver-copper nanoparticles by laser ablation of silver-copper targets in an aqueous solution environment, but the oxidation of copper elements could not be effectively inhibited (Synthesis and Mechanism of Composition and Size Dependent Morphology Selection in Nanoparticles of Ag–Cu Alloys Processed by Laser Ablation Under Liquid Medium [J]. Journal of Physical Chemistry C, 2014.). Summary of the invention

[0005] The present invention aims to provide a method for preparing ultrafine silver-copper nanoparticles by reactive liquid phase laser ablation. The method uses reactive laser ablation to prepare silver-copper alloy nanoparticles with high composition uniformity in an environment that inhibits oxidation.

[0006] The technical solution for achieving the purpose of the present invention is as follows:

[0007] The method for preparing ultrafine silver-copper nanoparticles by reactive liquid phase laser ablation comprises the following steps:

[0008] Step 1, copper target pretreatment: placing a pure copper target in a pretreatment solution, and coating a layer of silver film on the surface of the pure copper target, wherein the pretreatment solution is an ethanol solution containing silver nitrate and ethylenediamine;

[0009] Step 2, placing the pretreated copper target in a pretreatment solution to which a surfactant polyvinyl pyrrolidone PVP-K30 is added, focusing a pulsed laser beam on the contact surface between the copper target and the liquid phase while stirring, and generating silver-copper nanoparticles by liquid phase laser ablation reaction;

[0010] Step 3, centrifuging and drying the colloidal solution obtained in step 2 to obtain ultrafine silver-copper nanoparticles.

[0011] Preferably, in step 1, the purity of the pure copper target is ≥ 99.95%.

[0012] Preferably, in step 1, in the pretreatment solution, the molar ratio of ethylenediamine to silver nitrate is 4:1, and the concentration of silver nitrate is 2 g / L.

[0013] Preferably, in step 1, the pH value of the pretreatment solution is 9.8.

[0014] Preferably, in step 2, the concentration of PVP-K30 is 2 g / L.

[0015] Preferably, in step 2, the focal length is 650 mm, the wavelength of the pulsed laser beam is 1064 nm, the pulse width is 15 ps, the single pulse laser energy is 100 μJ, the laser power is 43.1 W, and the frequency is 100 kHz.

[0016] Preferably, in step 2, the ablation reaction time is 20 to 60 minutes.

[0017] Preferably, in step 3, the centrifugation condition is 10000 r / min for 30 minutes.

[0018] Preferably, in step 3, the drying condition is vacuum drying and the drying temperature is room temperature.

[0019] Preferably, in step 3, the particle size of the ultrafine silver-copper nanoparticles is 1 to 30 nm.

[0020] The present invention first pre-treats a pure copper target in an ethanol solution containing silver nitrate and ethylenediamine. Ethylenediamine is used as a complexing agent, and silver nitrate reacts with the ethylenediamine to coat a uniform and dense silver film on the surface of the pure copper target. Then the target is placed in a liquid phase formed by a surfactant, silver nitrate, ethylenediamine and ethanol, and a pulsed laser is focused on the surface of the target. The target is excited by the laser, and plasma is generated at the solid-liquid interface. The plasma will eventually form a cavitation bubble restricted by the liquid. The cavitation bubble is a high-temperature and high-pressure area, which will continue to expand, and finally the bubble will rupture and the particles will disperse and grow to form silver-copper nanoparticles. In the process of the disappearance of bubbles in the area of ​​laser ablation reaction, the pure copper area exposed after ablation reacts with the silver ions in the liquid phase to generate a new silver film, and the ethanol solution environment of the silver ions will inhibit the oxidation of copper. In addition, the surfactant prevents the excessive growth of nanoparticles on the one hand, and can also protect copper and prevent copper oxidation on the other hand. In the process of a pulsed laser, multiple reactions such as target ablation, plasma-solvent reaction, solvent decomposition and ion redox reaction will occur in parallel.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] (1) The present invention is the first to prepare ultrafine silver-copper nanoparticles in liquid phase using reactive pulsed laser ablation technology. The method is simple to operate, low in cost, and has low environmental requirements. It can prepare ultrafine silver-copper nanoparticles at room temperature and pressure.

[0023] (2) The method of the present invention is carried out in a special solution environment using a pulsed laser. Compared with the current liquid phase laser ablation method, it solves the problem of easy oxidation of copper in silver-copper particles. The obtained silver-copper nanoparticles have the characteristics of uniform composition, small particle size, and narrow size distribution. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the structure of the equipment used in the present invention.

[0025] Figure 2 2 are transmission electron micrographs of the ultrafine nano silver-copper particles obtained in Example 1 and Comparative Example 1, wherein (a) is a transmission electron micrograph of the ultrafine nano silver-copper particles prepared in Example 1, and (b) is a transmission electron micrograph of the silver-copper particles prepared in Comparative Example 1.

[0026] Figure 3 Figure 1 is a high-resolution image of the ultrafine nano-silver-copper particles obtained in Example 1, as well as an EDS mapping image and a line scan image, wherein Figure (a) is a high-resolution image of the ultrafine nano-silver-copper particles, Figures (b), (c), and (d) are EDS mapping images of the ultrafine nano-silver-copper particles, and Figure (e) is a line scan image of the ultrafine nano-silver-copper particles.

[0027] Figure 4 This is the ultraviolet absorption spectrum of the silver-copper nanoparticles obtained in Example 1. DETAILED DESCRIPTION

[0028] In order to enable those skilled in the art to better understand the technical solutions of the present invention, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0029] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0030] Example 1

[0031] like Figure 1 As shown, the device of the present invention includes a laser 1 (using Nd:YAG pulse laser, laser wavelength 1064nm, pulse width 15ps, single pulse laser energy 100μJ, laser power 43.1W, frequency 100kHz), a total reflection mirror 2, a focusing lens 3 (focal length 650mm), a glass container 4, a target material 5, and a magnetic stirrer 6.

[0032] (1) Preparation of pretreatment solution: Add 0.79 g of silver nitrate into ethanol and stir until the silver nitrate is completely dissolved. Then, absorb 1.24 ml of ethylenediamine, stir and ultrasonicate until the solution is evenly dispersed.

[0033] (2) Target pretreatment: 1.5 cm × 1.5 cm square pure copper target was suspended and immersed in the pretreatment solution for 15 minutes, and the target was taken out for later use.

[0034] (3) Preparation of ablation solution: Before ablation, 2 L of ablation solution was prepared. The pretreatment solution was used as the base solution, and a surfactant (PVP-K30) was added to the pretreatment solution. The concentration of the surfactant was 2 g / L, that is, the ablation solution contained 6.32 g of silver nitrate, 9.92 ml of ethylenediamine, and 6 g of the surfactant (PVP-K30).

[0035] (4) The target material 5 is placed flat in the glass container 4, and then the magnetic rotor is placed in the glass container 4. The glass container is then placed on the magnetic stirrer, and the magnetic stirrer is operated at a speed of 50 r / min.

[0036] (5) Slowly pour the ablation solution into the glass container 4 so that the target material 5 is immersed and the liquid level is 5 mm higher than the upper surface of the target material 5; adjust the laser light path so that the pulsed laser beam emitted by the laser 1 passes through the reflector 2 and the focusing lens 3, and then the focused laser irradiates the contact surface between the target material 5 and the liquid phase, and the laser frequency is 100 kHz; after the pulsed laser reacts with the silver-copper target material 5 for 30 minutes, turn off the laser.

[0037] (6) The colloidal solution after the reaction is taken out and dropped onto an ultra-thin carbon film copper mesh, and then placed in a vacuum drying oven for drying at room temperature to obtain ultra-fine silver-copper nanoparticles.

[0038] When the ultra-thin carbon film copper mesh is taken under a transmission electron microscope for magnified observation, dispersed spherical silver-copper nanoparticles can be seen on the substrate.

[0039] like Figure 2 (a) is a transmission electron microscope image of the ultrafine silver-copper nanoparticles prepared in this embodiment. It can be seen from the image that the particle size of the silver-copper nanoparticles is 10-20nm and has good dispersibility.

[0040] like Figure 3 The high-resolution image, EDS mapping image and line scan image of the ultrafine silver-copper nanoparticles prepared in this embodiment are shown in FIG. It can be seen from the figure that the silver-copper elements are evenly distributed and the particle size is small.

[0041] like Figure 4 , which is a UV-visible absorption spectrum of the prepared ultrafine silver-copper nanoparticles. The absorption peak at 418.8 nm in the figure is the plasma resonance absorption peak caused by the ultrafine silver-copper nanoparticles.

[0042] Comparative Example 1

[0043] This comparative example is basically the same as Example 1, except that the solvent ethanol in the pretreatment solution and the ablation solution is replaced with deionized water, that is, the liquid phase environment is a water environment.

[0044] like Figure 2 As shown in (b), the silver-copper nanoparticles generated in the aqueous liquid phase environment are severely aggregated.

Claims

1. A method for preparing ultrafine silver-copper nanoparticles by reactive liquid phase laser ablation, characterized in that: The following steps are involved: Step 1, copper target pretreatment: placing a pure copper target in a pretreatment solution, and coating a layer of silver film on the surface of the pure copper target, wherein the pretreatment solution is an ethanol solution containing silver nitrate and ethylenediamine, wherein the molar ratio of ethylenediamine to silver nitrate is 4:1, and the concentration of silver nitrate is 2 g / L; Step 2, placing the pretreated copper target in a pretreatment solution to which a surfactant polyvinyl pyrrolidone PVP-K30 is added, and a pulsed laser beam is focused on the contact surface between the copper target and the liquid phase while stirring, with a focal length of 650 mm, a wavelength of the pulsed laser beam of 1064 nm, a pulse width of 15 ps, a single pulse laser energy of 100 μJ, a laser power of 43.1 W, and a frequency of 100 kHz, and a liquid phase laser ablation reaction generates silver-copper nanoparticles; Step 3, centrifuging the colloidal solution obtained by the reaction in step 2, and drying to obtain ultrafine silver-copper nanoparticles with a particle size of 1 to 30 nm.

2. The method according to claim 1, characterized in that In step 1, the purity of the pure copper target is ≥99.95%.

3. The method according to claim 1, characterized in that In step 1, the pH value of the pretreatment solution is 9.

8.

4. The method according to claim 1, characterized in that: In step 2, the concentration of PVP-K30 is 2 g / L.

5. The method according to claim 1, characterized in that In step 2, the ablation reaction time is 20 to 60 minutes.

6. The method according to claim 1, characterized in that In step 3, the centrifugation condition is 10000r / min for 30 minutes.

7. The method according to claim 1, characterized in that In step 3, the drying condition is vacuum drying, and the drying temperature is room temperature.

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