A method for preparing amorphous magnesium-based nanoparticles and its application

Abstract

The present invention discloses a method for preparing amorphous magnesium-based nanoparticles and applications thereof, and belongs to the technical field of preparation of magnesium-based hydrogen storage materials. The present invention first prepares a magnesium-based alloy ingot by an induction melting method, and then rapidly heats the alloy ingot placed in an organic liquid phase by a pulsed ultrafast frequency laser, and rapidly quenches it to obtain amorphous magnesium-based nanoparticles with a size of about 2nm to 500nm. Compared with conventional methods, the preparation method of the present invention has high heating and cooling rates, a simple process, and is suitable for the preparation of binary and multinary magnesium-based amorphous particles. The amorphous magnesium-based nanoparticles prepared by the present invention have excellent hydrogen storage performance, can achieve reversible hydrogen storage at 50-120°C, and have good application prospects in fixed and mobile hydrogen storage systems.

Description

Technical Field

[0001] The invention belongs to the field of magnesium-based hydrogen storage alloy materials, and in particular relates to a preparation method of an amorphous magnesium-based nanoparticle material and an application thereof. Background Art

[0002] The storage of hydrogen energy is a key scientific issue for the large-scale commercial application of hydrogen energy. Magnesium-based materials have good application prospects due to their high hydrogen storage capacity, abundant resources, low cost, and environmental friendliness. However, the high thermodynamic stability and slow hydrogen absorption and desorption kinetics of traditional magnesium-based hydrogen storage alloys greatly limit their practical application, especially their dehydrogenation temperature is above 250-300°C and their dehydrogenation kinetics are relatively slow.

[0003] Amorphous alloys have the characteristics of short-range order and long-range disorder in microstructure. This disordered structure determines that amorphous alloys have very excellent physical, chemical and mechanical properties and have broad application prospects. They also show excellent performance in the field of hydrogen storage, such as high hydrogen storage capacity and fast kinetic performance. However, the dehydrogenation temperature of magnesium-based amorphous hydrogen storage alloys is still higher than their crystallization temperature, resulting in nanocrystallization below the dehydrogenation temperature. Therefore, the reversibility of magnesium-based amorphous alloys needs to be further improved.

[0004] The reversibility of hydrogen storage can be improved by nano-sizing. Earlier researchers reported that magnesium-based nano hydrogen storage materials in the form of nano powders, nano films, nano wires, etc. can significantly improve hydrogen storage kinetics, thermodynamics and cycle performance. However, there are currently very few methods for preparing amorphous magnesium-based nanoparticles, and there have been no reports on the successful preparation of amorphous magnesium-based nanoparticles below 10nm. Summary of the invention

[0005] The purpose of the present invention is to provide a method for preparing amorphous magnesium alloy nanoparticles in view of the shortcomings of the prior art. The technical solution of the present invention prepares amorphous magnesium alloy nanoparticles by a laser liquid phase method. The prepared magnesium-based amorphous nanoparticles have excellent hydrogen absorption and desorption kinetics, especially they can dehydrogenate at 50-120°C, and have good application prospects in fixed and mobile hydrogen storage systems.

[0006] In order to achieve the above object, the present invention adopts the following technical solution:

[0007] A method for preparing amorphous magnesium-based alloy nanoparticles by a laser liquid phase method comprises the following steps:

[0008] S1: preheating the magnesium alloy ingot, adding materials uniformly according to the atomic mass percentage of the set binary and multi-element alloys, and then performing induction melting to prepare binary and multi-element magnesium-based alloy ingots under the protection of inert gas;

[0009] S2: cutting the magnesium-based alloy ingot obtained by smelting in step S1 into a block sample with a thickness of 0.2-2.0 cm;

[0010] S3: placing the cube sample prepared in step S2 in an organic solvent to obtain a liquid cube sample;

[0011] S4: Melting the block sample in the liquid phase of step S3 by a high-power pulse laser;

[0012] S5: vacuum drying the solution obtained in S4 to obtain amorphous magnesium-based nanoparticles.

[0013] Preferably, as a preferred embodiment, the molar ratio of magnesium atoms in the magnesium alloy ingot in step S1 is greater than 50%, and the temperature of the induction melting is 650-1200°C; at the same time, in order to make up for the loss of magnesium alloy evaporated during the melting process, the mass of magnesium powder added is about 5% more than the theoretical calculation;

[0014] Preferably, as a preferred embodiment, the surface area of ​​the block sample in step S2 is about 1-4 cm.

[0015] Preferably, as a preferred embodiment, the organic solvent in step S3 is selected from one or more of high-purity acetone, high-purity tetrahydrofuran, and high-purity toluene, and the sample surface is about 1-10 mm away from the liquid surface. Preferably, as a preferred embodiment, a picosecond pulse laser is selected in step S4.

[0016] The wavelength is 225nm-425nm, the power is 18-100W, and the scanning time is 1-100 minutes.

[0017] Preferably, as a preferred embodiment, the vacuum drying in step S5 is performed at room temperature, or the temperature can be first raised to 50° C., the vacuum degree is about 10-100 Pa, and the vacuum time can be adjusted according to the amount of the solution, specifically 10-300 min.

[0018] Another object of the present invention is to provide a magnesium-based amorphous nanoparticle prepared according to the above preparation method. The dehydrogenation power of the magnesium-based amorphous nanoparticle material prepared by the preparation method of the present invention is greatly improved, and the dehydrogenation temperature is 50-120°C.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] (1) After the preparation method of the present invention performs a specific activation process on the amorphous alloy, the grains of the alloy are significantly refined, with a size of only 2-500 nm;

[0021] (2) The preparation method of the present invention utilizes the rapid heating and cooling effect of picosecond laser to in-situ generate amorphous nanoparticles in the liquid phase of the atmospheric environment. The sample only needs to be in the atmospheric environment, and there is no need to seal the sample in a quartz tube, and no additional packaging or additional equipment is required;

[0022] (3) The magnesium-based nano-amorphous particles prepared by the preparation method of the present invention are formed by in-situ cooling in an organic solution, and no additional rapid cooling method is required;

[0023] (4) The dehydrogenation kinetics of the material has been greatly improved, and the dehydrogenation temperature is about 50-120°C; the preparation process is simple, the yield and stability are high, and it is suitable for large-scale industrial production. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The laser liquid phase prepared Mg 80 Ni 20 TEM image of amorphous nanoparticles;

[0025] Figure 2 The laser liquid phase prepared Mg 80 Ni 20 Particle size distribution of amorphous nanoparticles;

[0026] Figure 3 The laser liquid phase prepared Mg 80 Ni 20 Energy spectrum of amorphous nanoparticles;

[0027] Figure 4 The laser liquid phase prepared Mg 80 Ce 10 Ni 10 TEM image of amorphous nanoparticles;

[0028] Figure 5 The laser liquid phase prepared Mg 80 Ce 10 Ni 10 Particle size distribution of amorphous nanoparticles;

[0029] Figure 6 The laser liquid phase prepared Mg 80 Ce 10 Ni 10 Energy spectrum of amorphous nanoparticles;

[0030] Figure 7 The laser liquid phase prepared Mg 65 Ce 10 Ni 20 TEM image of Cu5 amorphous nanoparticles;

[0031] Figure 8The laser liquid phase prepared Mg 65 Ce 10 Ni 20 Particle size distribution of Cu5 amorphous nanoparticles;

[0032] Fig. 9 The laser liquid phase prepared Mg 65 Ce 10 Ni 20 Energy spectrum of Cu5 amorphous nanoparticles;

[0033] Fig.10 It shows that Mg 80 Ni 20 Dehydrogenation TPD curve of amorphous nanoparticles;

[0034] Fig.11 It shows that Mg 80 Ce 10 Ni 10 Dehydrogenation kinetics of amorphous nanoparticles after 1, 2, 3, and 4 cycles;

[0035] Fig.12 It shows that Mg 65 Ce 10 Ni 20 Dehydrogenation kinetics of Cu5 amorphous nanoparticles after 1, 2, 3, 4, and 5 cycles. DETAILED DESCRIPTION

[0036] 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.

[0037] 1. Embodiment 1

[0038] Nickel ingot (99.99%) and magnesium ingot (99.99%) were mixed in a molar ratio of 8:2, and smelted by arc smelting for 5-8 times. 80 Ni 20 The alloy is cut to obtain a 1-2 cm block of matrix material; the cut matrix material is placed in high-purity acetone until the liquid level completely covers the block surface by 2-3 mm. The matrix material in the liquid phase is rapidly eroded by a picosecond laser, and the morphology of the obtained amorphous nanoparticles is as follows: Figure 1 shown.

[0039] Figure 2 The particle size distribution after the particles are collected and dried is obtained. Figure 3 This is its energy spectrum, which shows that the size of the amorphous particles is very small. The average particle size is calculated to be 9.8nm.

[0040] Fig.10The dehydrogenation kinetics test curve of the activated sample is shown in Figure 2.

[0041] 2. Embodiment 2

[0042] Cerium ingot (99.9%) and nickel ingot (99.99%) were mixed in a molar ratio of 1:1, and smelted by arc smelting, and the smelting was repeated 5-8 times. Cerium-nickel master alloy and magnesium ingot (99.99%) were mixed and prepared by induction smelting; the prepared Mg 80 Ce 10 Ni 10 The alloy is cut to obtain a 1-2 cm block of the matrix; the cut matrix is ​​placed in high-purity acetone until the liquid level completely covers the block surface by 2-3 mm. The matrix in the liquid phase is rapidly heated using a picosecond laser, and the morphology of the obtained amorphous nanoparticles is as follows: Figure 4 shown.

[0043] Figure 5 The particle size distribution after the particles are collected and dried is obtained. Figure 6 This is its energy spectrum, which shows that the size of the amorphous particles is very small. The average particle size is calculated to be 8.6nm.

[0044] Fig.11 This is the dehydrogenation kinetic curve of the activated sample after 4 cycles of hydrogen absorption and desorption. The dehydrogenation performance can be well maintained after the cycle.

[0045] 3. Embodiment 3

[0046] Cerium ingot (99.9%), nickel ingot (99.99%), and copper ingot (99.9%) were mixed in a molar ratio of 2:4:1, and smelted by arc smelting, and the smelting was repeated 5-8 times. Cerium-nickel-copper master alloy and magnesium ingot (99.99%) were mixed and prepared by induction smelting; the prepared Mg 65 Ce 10 Ni 20 The Cu5 alloy is cut to obtain a 1-2 cm block of the matrix; the cut matrix is ​​placed in high-purity acetone until the liquid level completely covers the block surface by 2-3 mm. The bulk matrix placed in the liquid phase is rapidly heated using a picosecond laser, and the morphology of the obtained amorphous nanoparticles is as follows: Figure 7 shown.

[0047] Figure 8 The particle size distribution after the particles are collected and dried is obtained. Fig. 9 This is its energy spectrum, which shows that the size of the amorphous particles is very small. The average particle size is calculated to be 8.9nm.

[0048] Fig.12This is a dehydrogenation kinetic curve of the activated sample after 5 cycles of hydrogen absorption and desorption.

[0049] The above-mentioned specific implementation modes are preferred embodiments of the present invention and cannot limit the claims of the present invention. Any other changes or other equivalent replacement methods that do not deviate from the technical solution of the present invention are included in the protection scope of the present invention.

Claims

1. A method for preparing amorphous magnesium-based alloy nanoparticles by laser liquid phase method, characterized in that: The steps include: S1 preheating the magnesium alloy ingot, uniformly adding materials according to the atomic mass percentage of the set binary or multi-element alloy, and then performing induction melting to prepare binary and multi-element magnesium-based alloy ingots under the protection of inert gas; S2: cutting the magnesium-based alloy ingot obtained by smelting in step S1 into a block sample with a thickness of 0.2-2.0 cm; S3 placing the cube sample prepared in step S2 in an organic solvent to obtain a liquid cube sample; S4 melts the block-shaped sample in the liquid phase of step S3 by a picosecond pulse laser; S5 vacuum-drying the solution obtained in S4 to obtain amorphous magnesium-based nanoparticles; Wherein, the molar ratio of magnesium atoms in the magnesium alloy ingot in step S1 is greater than 50%, and the temperature of the induction melting is 650-1200 o C; the magnesium-based alloy ingot is obtained by smelting a magnesium ingot and one or more selected from a nickel ingot, a cerium ingot, and a copper ingot; The picosecond pulse laser has a wavelength of 225 nm-425 nm, a power of 18-100 W, and a scanning time of 1-100 minutes.

2. The method for preparing amorphous magnesium-based alloy nanoparticles by laser liquid phase method according to claim 1, characterized in that: The surface area of ​​the block sample in step S2 is 1-4 cm.

3. The method for preparing amorphous magnesium-based alloy nanoparticles by laser liquid phase method according to claim 1, characterized in that: In step S3, the organic solvent is selected from one or more of high-purity acetone, high-purity tetrahydrofuran, and high-purity toluene, and the surface of the sample is 1-10 mm away from the liquid surface.

4. Amorphous magnesium-based alloy nanoparticles prepared according to the method of any one of claims 1 to 3.

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