Preparation method of metal nanoparticles with accurate morphology control

Abstract

The application discloses a preparation method of metal nanoparticles with accurate morphology control. The preparation method is that an electrolyte is electrolyzed by using a conductive anode material, and the morphology of the nanometer metal particles deposited on the conductive cathode is accurately controlled by adjusting the type of the additive in the electrolyte. The application also provides a preparation method of the additive in the electrolyte. By controlling the type of the additive, the nanometer metal particles with accurate morphology control, such as spherical, flower-shaped, urchin-shaped, flaky and cubic shapes, can be deposited. The ionic liquid synthesized by the application can be used as an additive in the electrolyte, and can be used as an electrodeposition electrolyte additive for accurately controlling the morphology of the nanometer metal particles. The ionic liquid can accurately control the morphology of the nanometer metal particles prepared by electrodeposition, is beneficial to reducing the production steps of the nanometer metal particles with different morphologies and reducing the production cost, and has the characteristics of low energy consumption, high yield, simple process, safety and environmental protection and the like.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical technology, specifically relating to a method for preparing metal nanoparticles with precisely controlled morphology. Background Technology

[0002] In recent years, with the development of various novel properties and applications of nano-metal particles, the field of nano-metal particles has flourished, becoming a fundamental material for the preparation of various novel key functional materials. The preparation of nano-metal particles mainly includes chemical and physical methods. Chemical methods include high-temperature pyrolysis and liquid-phase reduction, while physical methods include hydrothermal and solvothermal methods. Liquid-phase reduction can roughly control the morphology and size of particles, but requires the addition of large amounts of surfactants and generates significant amounts of wastewater. High-temperature pyrolysis and arc evaporation-condensation are also common methods for synthesizing metal particles and controlling their morphology, but they are energy-intensive, and the nano-metal particles often have a wide particle size distribution. Physical crushing and evaporation-condensation methods, such as ball milling and pulverization, produce nano-metal particles that are large in size, unevenly distributed, and have many defects. Therefore, chemical methods for preparing nano-metal particles have low energy consumption, simple processes, and easily controllable and uniform product morphology.

[0003] Metal electrodeposition is a technique that uses electrochemical principles to deposit one or more metal ions from an electrolyte onto the surface of a cathode. By controlling the electrodeposition parameters and electrolyte composition, nanoparticles of different metals and morphologies can be prepared by electrodeposition. However, current reports on the preparation and precise control of the morphology of nano-metal particles using electrodeposition are limited and restricted to bulk, sheet, and powder morphologies, making it difficult to meet the needs of multifunctional applications.

[0004] CN201710399752.3 describes a method for preparing finer Cu, Fe, Co, and Ni particles using the electrolysis of aqueous solutions of metal salts, but this method is energy-intensive and does not achieve effective control over the morphology of the nanoparticles. CN201710098703.6 describes a method for electrodepositing powdered metals using graphite felt or carbon felt as the anode, but this method does not achieve control over the morphology of the metal powder and has high production costs. CN201911117064.9 discloses a method for preparing metal nanoparticles by continuous electrochemical deposition, achieving continuous preparation and exfoliation of Ag, Cu, Au, Co, and Ni particles, but it cannot precisely control the morphology of the nanoparticles. Therefore, how to achieve precise and effective control over the morphology of nanoparticles has always been a research challenge in the field of nanoparticle preparation. Summary of the Invention

[0005] To address the problem of the difficulty in precisely and effectively controlling the morphology of existing electrodeposited nano-metal particles, this invention utilizes ionic liquids as additives to induce precise control over the morphology of electrodeposited nano-metal particles, thereby preparing nano-metal particles with shapes such as spheres, flowers, sea urchins, sheets, and cubes.

[0006] The purpose of this invention is to precisely control the morphology of electrodeposited nano-metal particles. By changing the type of ionic liquid in the electrodeposition electrolyte, electrodeposited nano-metal particles with different structural shapes can be obtained, such as spherical, flower-like, sea urchin-like, plate-like, and cubic shapes.

[0007] To achieve the above objectives, the present invention first provides an ionic liquid additive for an ionic liquid electrodeposition electrolyte with a structure as shown in formula (I-I), (I-II), (I-III), (I-IV), (I-V), or (I-VI);

[0008]

[0009] The preparation method of the ionic liquid additive with the structure shown in formula (Ⅰ-Ⅰ), (Ⅰ-Ⅱ), (Ⅰ-Ⅲ), (Ⅰ-Ⅳ), (Ⅰ-Ⅴ), or (Ⅰ-Ⅵ) of this invention is specifically carried out according to the following steps:

[0010] (1) Dissolve the intermediate product shown in formula II, III, IV, V, VI, or VII in acetonitrile solution to obtain reaction solution A;

[0011] (2) The acetonitrile solution of halotriene R2 is added dropwise to reaction solution A and reacted at 60-90℃ for 12-24h to obtain reaction solution B. After post-treatment, an ionic liquid with the structure shown in formula (I-I) or (I-II) or (I-III) or (I-IV) or (I-V) or (I-VI) is obtained; the ratio between the intermediate product shown in formula II or III or IV or V or VI or VII and the amount of halotriene R2 added is 1:1.0-1.5.

[0012]

[0013] Furthermore, in step (1), the volume of acetonitrile used is recorded as 10 to 20 mL / g based on the mass of the intermediate product represented by formula II, III, IV, V, VI, or VII.

[0014] Furthermore, in step (2), the halogen in the halogenated compound R2 should be chlorine, bromine or iodine.

[0015] Furthermore, in step (2), R2 in the halogenated compound R2 should be an alkane, aromatic hydrocarbon, ester, ether or carboxylic acid with a carbon chain length of 2 to 15.

[0016] Furthermore, in step (2), the volume of acetonitrile used is expressed as 1 to 5 mL / g based on the mass of the halogenated product R2.

[0017] Further, in step (2), the post-treatment method of the reaction solution B is as follows: the solvent acetonitrile is evaporated from the reaction solution B under reduced pressure, the remaining mixture is washed thoroughly three times with diethyl ether, the solvent is evaporated under reduced pressure and dried thoroughly to obtain an ionic liquid with the structure shown in formula (Ⅰ-Ⅰ) or (Ⅰ-Ⅱ) or (Ⅰ-Ⅲ) or (Ⅰ-Ⅳ) or (Ⅰ-Ⅴ) or (Ⅰ-Ⅵ).

[0018] The intermediate products represented by formula II, III, IV, V, VI, or VII of this invention are prepared according to the following steps:

[0019] Imidazole, morpholine, piperidine, pyrrolidine, pyrazole, or tertiary amine are mixed with sodium hydroxide, potassium hydroxide, or potassium carbonate and acetonitrile. The mixture is stirred at room temperature for 3 hours to obtain reaction solution C. Halogen R1 is added to reaction solution C, and the reaction is continued under reflux for 48 hours to obtain reaction solution D. Deionized water is added to the reaction solution, and the mixture is extracted with dichloromethane. The organic phase is collected, thoroughly dried with anhydrous sodium sulfate, and finally the solvent is removed under reduced pressure to obtain the intermediate product represented by formula II, III, IV, V, VI, or VII. The ratio of the amount of imidazole, morpholine, piperidine, pyrrolidine, pyrazole, or tertiary amine to sodium hydroxide, potassium hydroxide, or potassium carbonate is 1:1 to 3. The volume of acetonitrile used is expressed as 1 mmol / 1 to 3 mL of sodium hydroxide, potassium hydroxide, or potassium carbonate. The halogen in the halogenated product R1 is chlorine, bromine, or iodine. The R in the halogenated product R1 is an alkane, aromatic hydrocarbon, ester, ether, or carboxylic acid with a carbon chain length of 2 to 15.

[0020] The target product was characterized by proton nuclear magnetic resonance (NMR) spectroscopy and Fourier transform infrared (FT-IR) spectroscopy. The electrochemistry of the obtained ionic liquid additive was characterized using a Metrohm AutoLab 302N electrochemical workstation. The ionic liquid additive prepared by this invention exhibits good electrochemical stability and can be used as an electrolyte additive to induce precise control over the morphology of electrodeposited nanomaterials.

[0021] To achieve the aforementioned goal of precisely controlling the morphology of electrodeposited nano-metal particles, the present invention employs the following technical solution: two conductive electrodes are placed side by side in an electrolyte containing ionic liquid additives, and the two conductive electrodes are respectively connected to the positive and negative terminals of a DC bias power supply. A bias voltage is applied at room temperature to obtain nano-metal particles with precisely controlled morphology.

[0022] The conductive electrode is one of indium tin oxide conductive glass, fluorine-doped tin oxide conductive glass, conductive silver plate, or nickel plate, and the distance between the two conductive electrodes is 1-10 cm; the applied bias voltage is 1-10 V; the shape of the precisely morphologically controlled nano-metal particles is one of spherical, flower-like, sea urchin-like, plate-like, and cubic shapes.

[0023] In one specific embodiment of the present invention, the ionic liquid additive is one or more combinations of the structures shown in formula (I-I), (I-II), (I-III), (I-IV), (I-V), or (I-VI); the solvent of the electrolyte is one or more combinations of N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, N-methylpyrrolidone, propylene carbonate, ethylene carbonate, dimethyl carbonate, ethyl methyl carbonate, and γ-butyrolactone; the mass amount of the ionic liquid additive is 0.1-5 g / mL based on the volume of the electrolyte solvent.

[0024] In one specific embodiment of the present invention, the electrolyte should also contain one or more of the following salts necessary for preparing nano-metal particles: gold, silver, copper, iron, zinc, nickel, aluminum, and magnesium salts; the anions of the gold, silver, copper, iron, zinc, nickel, aluminum, or magnesium salts are one of sulfate, sulfite, nitrate, perchlorate, hypochlorite, chloride, bromide, or iodide anions.

[0025] The ionic liquids prepared according to the present invention, with structures as shown in formula (Ⅰ-Ⅰ), (Ⅰ-Ⅱ), (Ⅰ-Ⅲ), (Ⅰ-Ⅳ), (Ⅰ-Ⅴ), or (Ⅰ-Ⅵ), can be used as additives to induce metal electrodeposition and precisely control the morphology of nano-metal particles.

[0026] The present invention describes a method for precisely controlling the morphology of nano-metal particles by electrodeposition of an electrolyte containing ionic liquid additives, thereby preparing nano-metal particles with shapes such as spheres, flowers, sea urchins, sheets, or cubes.

[0027] Compared with the prior art, the present invention has the following advantages:

[0028] This invention synthesizes an ionic liquid that can be used as an electrolyte additive. It can be used as an electrodeposition electrolyte additive for precisely controlling the morphology of nano-metal particles. It can precisely control the morphology of nano-metal particles prepared by electrodeposition, which helps to reduce the production steps of nano-metal particles with different morphologies and reduce production costs. At the same time, it has the characteristics of low energy consumption, high yield, simple process and safety and environmental protection. Attached Figure Description

[0029] Figure 1 : A schematic diagram of the electrodeposition apparatus in an embodiment of the present invention;

[0030] Figure 2 Morphology of the electrodeposited silver metal particles in Example 8 of this invention;

[0031] Figure 3 Morphology of the electrodeposited silver metal particles in Example 9 of this invention;

[0032] Figure 4 Morphology of the electrodeposited silver metal particles in Example 10 of this invention;

[0033] Figure 5 Morphology of the electrodeposited silver metal particles in Example 11 of this invention;

[0034] Figure 6 Morphology of the electrodeposited silver metal particles in Example 12 of this invention;

[0035] Figure 7 Morphology of the electrodeposited silver metal particles in Example 13 of this invention; Detailed Implementation

[0036] The technical solution of the present invention will be further described below with reference to specific embodiments, but the scope of protection of the present invention is not limited thereto.

[0037] like Figure 1 The image shows an electrodeposition device for precisely controlling the morphology of electrodeposited nano-metal particles provided in this embodiment.

[0038] Example 11, Synthesis of 3-diheptylimidazolium bromide

[0039] Imidazole (20.0 mmol) and KOH (20.0 mmol) were stirred in CH3CN (20.0 mL) at 25 °C for 3 h. Then, 1-bromoheptane (20.0 mmol) was added to the mixture, and the reaction was continued under reflux for 48 h. The volatile solvent CH3CN was removed from the reaction mixture by rotary evaporation under reduced pressure. CH2Cl2 was added to the residue, and the mixture was extracted three times with water. The organic phase was thoroughly dried with anhydrous Na2SO4. The collected organic phase filtrate was solvent-removed by rotary evaporation under reduced pressure, and then thoroughly washed three times with diethyl ether. The solid product obtained after removing the diethyl ether was dried in a dynamic vacuum oven at 45 °C for 24 h to give the intermediate product shown in formula (II). The intermediate product (20.0 mmol) shown in formula (II) and 1-bromoheptane (20.0 mmol) were further reacted in CH3CN (20.0 mL) under reflux for 48 h at 25 °C. The reaction mixture was subjected to rotary vacuum evaporation to remove the volatile solvent CH3CN, and then thoroughly washed three times with diethyl ether. The solid product obtained after removing the diethyl ether was finally dried in a dynamic vacuum oven at 45°C for 24 h to obtain a brownish-red viscous liquid product with R1 and R2 of formula (Ⅰ-Ⅰ) having a carbon chain length of 7 and halogen X being bromine, with a yield of 88.5%.

[0040]

[0041] Example 21, Synthesis of 1-diheptylmorpholine bromide

[0042] At 25 °C, morpholine (20.0 mmol) and KOH (20.0 mmol) were stirred in CH3CN (20.0 mL) for 3 h, and then 1-bromoheptane (20.0 mmol) was added to the mixture, and the reaction was continued under reflux for 48 h. The volatile solvent CH3CN was removed from the reaction mixture by rotary evaporation under reduced pressure. CH2Cl2 was added to the residue, and the mixture was extracted three times with water. The organic phase was thoroughly dried with anhydrous Na2SO4. The collected organic phase filtrate was solvent-removed by rotary evaporation under reduced pressure, and then thoroughly washed three times with diethyl ether. The solid product obtained after removing the diethyl ether was finally dried in a dynamic vacuum oven at 45 °C for 24 h to give the intermediate product shown in formula (III). At 25 °C, the intermediate product (20.0 mmol) shown in formula (III) and 1-bromoheptane (20.0 mmol) were further reacted in CH3CN (20.0 mL) under reflux for 48 h. The reaction mixture was subjected to rotary vacuum evaporation to remove the volatile solvent CH3CN, and then thoroughly washed three times with diethyl ether. The solid product obtained after removing the diethyl ether was finally dried in a dynamic vacuum oven at 45°C for 24 h to obtain a white powder solid product with R1 and R2 of formula (Ⅰ-Ⅱ) having a carbon chain length of 7 and halogen X being bromine, with a yield of 78.9%.

[0043]

[0044] Example 31, Synthesis of 1-diheptylpiperidine bromide

[0045] Piperidine (20.0 mmol) and KOH (20.0 mmol) were stirred in CH3CN (20.0 mL) at 25 °C for 3 h. Then, 1-bromoheptane (20.0 mmol) was added to the mixture, and the reaction was continued under reflux for 48 h. The volatile solvent CH3CN was removed from the reaction mixture by rotary evaporation under reduced pressure. CH2Cl2 was added to the residue, and the mixture was extracted three times with water. The organic phase was thoroughly dried with anhydrous Na2SO4. The collected organic phase filtrate was solvent-removed by rotary evaporation under reduced pressure, and then thoroughly washed three times with diethyl ether. The solid product obtained after removing the diethyl ether was finally dried in a dynamic vacuum oven at 45 °C for 24 h to give the intermediate product shown in formula (Ⅳ). The intermediate product (20.0 mmol) shown in formula (Ⅳ) and 1-bromoheptane (20.0 mmol) were further reacted in CH3CN (20.0 mL) under reflux for 48 h at 25 °C. The reaction mixture was subjected to rotary vacuum evaporation to remove the volatile solvent CH3CN, and then thoroughly washed three times with diethyl ether. The solid product obtained after removing the diethyl ether was finally dried in a dynamic vacuum oven at 45°C for 24 h to obtain a white powder solid product with R1 and R2 of formula (Ⅰ-Ⅲ) having a carbon chain length of 7 and halogen X being bromine, with a yield of 92.7%.

[0046]

[0047] Example 41, Synthesis of 1,1-diheptylpyrrole bromide

[0048] At 25 °C, pyrrolidine (20.0 mmol) and KOH (20.0 mmol) were stirred in CH3CN (20.0 mL) for 3 h, and then 1-bromoheptane (20.0 mmol) was added to the mixture, and the reaction was continued under reflux for 48 h. The volatile solvent CH3CN was removed from the reaction mixture by rotary evaporation under reduced pressure. CH2Cl2 was added to the residue, and the mixture was extracted three times with water. The organic phase was thoroughly dried with anhydrous Na2SO4. The collected organic phase filtrate was solvent-removed by rotary evaporation under reduced pressure, and then thoroughly washed three times with diethyl ether. The solid product obtained after removing the diethyl ether was finally dried in a dynamic vacuum oven at 45 °C for 24 h to give the intermediate product shown in formula (V). At 25 °C, the intermediate product (20.0 mmol) shown in formula (V) and 1-bromoheptane (20.0 mmol) were further reacted with CH3CN (20.0 mL) under reflux for 48 h. The reaction mixture was subjected to rotary vacuum evaporation to remove the volatile solvent CH3CN, and then thoroughly washed three times with diethyl ether. The solid product obtained after removing the diethyl ether was finally dried in a dynamic vacuum oven at 45°C for 24 h to obtain a white solid product with R1 and R2 of formula (Ⅰ-Ⅳ) having a carbon chain length of 7 and halogen X being bromine, with a yield of 83.1%. 1HNMR (400MHz, CDCl3): δ5.95(s,4H),5.78–5.63(m,4H),4.61(s,4H),4.27–4.06(m,4H),3.83(dd,4H),3.40(t,6H).

[0049]

[0050] Example 51, Synthesis of 2-diheptylpyrazole bromide

[0051] At 25 °C, pyrazole (20.0 mmol) and KOH (20.0 mmol) were stirred in CH3CN (20.0 mL) for 3 h, and then 1-bromoheptane (20.0 mmol) was added to the mixture, and the reaction was continued under reflux for 48 h. The volatile solvent CH3CN was removed from the reaction mixture by rotary evaporation under reduced pressure. CH2Cl2 was added to the residue, and the mixture was extracted three times with water. The organic phase was thoroughly dried with anhydrous Na2SO4. The collected organic phase filtrate was solvent-removed by rotary evaporation under reduced pressure, and then thoroughly washed three times with diethyl ether. The solid product obtained after removing the diethyl ether was finally dried in a dynamic vacuum oven at 45 °C for 24 h to give the intermediate product shown in formula (VI). At 25 °C, the intermediate product (20.0 mmol) shown in formula (VI) and 1-bromoheptane (20.0 mmol) were further reacted in CH3CN (20.0 mL) under reflux for 48 h. The reaction mixture was subjected to rotary vacuum evaporation to remove the volatile solvent CH3CN, and then thoroughly washed three times with diethyl ether. The solid product obtained after removing the diethyl ether was finally dried in a dynamic vacuum oven at 45°C for 24 h to obtain a white solid product with R1 and R2 of formula (Ⅰ-Ⅴ) having a carbon chain length of 7 and halogen X being bromine, with a yield of 66.7%.

[0052]

[0053] Example 6 Synthesis of N,N,N-Tributyl-N-Heptylammonium Bromide

[0054] At 25 °C, the intermediate product (20.0 mmol) shown in formula (Ⅶ) reacted with 1-bromoheptane (20.0 mmol) in CH3CN (20.0 mL) under reflux for 48 h. The volatile solvent CH3CN was removed from the reaction mixture by rotary evaporation under reduced pressure, followed by thorough washing three times with diethyl ether. The solid product obtained after removing the diethyl ether was finally dried in a dynamic vacuum oven at 45 °C for 24 h to obtain the product shown in formula (Ⅰ-Ⅵ) with a carbon chain length of 4 for R1, a carbon chain length of 7 for R2, and halogen X as a white solid powder, with a yield of 95.2%.

[0055]

[0056] Example 7

[0057] This embodiment provides an electrodeposition device for precisely controlling the morphology of electrodeposited nano-metal particles. It includes two conductive electrodes 1 and 3 arranged in parallel and corresponding positions in an electrolytic cell 4, and an electrolyte 2 formed between the two conductive electrodes. The specific manufacturing process is as follows: the electrolyte 2 containing ionic liquid additives, metal salts and solvents is placed in the electrolytic cell, and the conductive surfaces of the two conductive electrodes (indium tin oxide glass) 1 and 3 are placed in parallel relative to each other, serving as the anode and cathode respectively.

[0058] Example 8

[0059] This embodiment provides a technical solution for precisely controlling the morphology of electrodeposited nano-metal particles to be sheet-like. 10-50 parts of an ionic liquid (shown in formula (Ⅰ-Ⅰ) where R1 and R2 are both carbon chain lengths of 7 and halogen X is bromine) are dissolved in a solution of 2-10 parts silver nitrate and 20-50 parts dimethyl sulfoxide, and thoroughly stirred. The resulting electrodeposition electrolyte is placed in an electrolytic cell. Two conductive electrodes with a thickness of 0.5 mm are used, spaced 5 cm apart, and a bias voltage of 2 V is applied. Sheet-like nanoparticles of metallic silver are obtained at the cathode. Figure 2 As shown.

[0060] Example 9

[0061] This embodiment provides a technical solution for precisely controlling the morphology of electrodeposited nano-metal particles to be spherical. It is basically the same as that in Example 8, except that the electrolyte 2 uses an ionic liquid with R1 and R2 as shown in formula (Ⅰ-Ⅱ), both having a carbon chain length of 7 and halogen X being bromine. Spherical silver particles are obtained at the cathode, as shown... Figure 3 As shown.

[0062] Example 10

[0063] This embodiment provides a technical solution for precisely controlling the morphology of electrodeposited nano-metal particles to resemble sea urchins. It is essentially the same as that in Example 8, except that the electrolyte 2 uses an ionic liquid with R1 and R2 as shown in formulas (I-III), both having a carbon chain length of 7 and halogen X being bromine. Sea urchin-shaped particles of metallic silver are obtained at the cathode, as shown... Figure 4 As shown.

[0064] Example 11

[0065] This embodiment provides a technical solution for precisely controlling the morphology of electrodeposited nanometal particles into a flower-like structure. It is essentially the same as that in Example 8, except that the electrolyte 2 uses an ionic liquid with R1 and R2 as shown in formulas (I-IV), both having a carbon chain length of 7 and halogen X being bromine. Flower-like particles of metallic silver are obtained at the cathode, as shown... Figure 5 As shown.

[0066] Example 12

[0067] This embodiment provides a technical solution for precisely controlling the morphology of electrodeposited nanometal particles to a cubic shape. It is basically the same as that in Example 8, except that the electrolyte 2 uses an ionic liquid with R1 and R2 as shown in formula (I-V), both having a carbon chain length of 7 and halogen X being bromine. Cubic silver particles are obtained at the cathode, as shown... Figure 6 As shown.

[0068] Example 13

[0069] This embodiment provides a technical solution for precisely controlling the morphology of electrodeposited nano-metal particles to be irregular, which is basically the same as that in Example 8, except that the electrolyte 2 used is an ionic liquid of formula (I-VI) with R1 carbon chain length of 4, R2 carbon chain length of 7, and halogen X being bromine. Irregularly shaped metallic silver particles are obtained at the cathode, such as... Figure 7 As shown.

[0070] The above embodiments are only for illustrating the technical concept and features of the present invention, and are intended to enable those skilled in the art to understand the content of the present invention and implement it accordingly. They should not be construed as limiting the scope of protection of the present invention. All equivalent changes or modifications made in accordance with the spirit and essence of the present invention should be covered within the scope of protection of the present invention.

Claims

1. A method for preparing nano-metal particles with precisely controlled morphology, characterized in that: By changing the type of additives in the electrodeposition electrolyte, electrodeposited silver nanoparticles with different structural shapes were obtained, including spherical, flower-like, sea urchin-like, plate-like, and cubic shapes. The additive in the electrolyte is an ionic liquid with a structure as shown in formula (Ⅰ-Ⅰ), (Ⅰ-Ⅱ), (Ⅰ-Ⅲ), (Ⅰ-Ⅳ), (Ⅰ-Ⅴ), or (Ⅰ-Ⅵ): ； R1 and R2 are both selected from heptyl or butyl; X is a halogen.

2. The method for preparing nano-metal particles with precisely controlled morphology as described in claim 1, characterized in that: The ionic liquid additives with structures shown in formula (Ⅰ-Ⅰ), (Ⅰ-Ⅱ), (Ⅰ-Ⅲ), (Ⅰ-Ⅳ), (Ⅰ-Ⅴ), or (Ⅰ-Ⅵ) in the electrolyte are prepared according to the following steps: (1) Dissolve the intermediate product shown in formula II, III, IV, V, VI, or VII in acetonitrile solution to obtain reaction solution A; (2) Add the acetonitrile solution of halo derivative R2 dropwise into reaction solution A and react at 60~90℃ for 12~24h to obtain reaction solution B. After post-treatment, obtain the ionic liquid with the structure shown in formula (Ⅰ-Ⅰ) or (Ⅰ-Ⅱ) or (Ⅰ-Ⅲ) or (Ⅰ-Ⅳ) or (Ⅰ-Ⅴ) or (Ⅰ-Ⅵ). 。 3. The method for preparing nano-metal particles with precisely controlled morphology as described in claim 2, characterized in that: The ratio between the intermediate product represented by formula II, III, IV, V, VI, or VII and the amount of halogenated product R2 is 1:1.0~1.

5.

4. The method for preparing nano-metal particles with precisely controlled morphology as described in claim 2, characterized in that: The post-treatment method of reaction solution B in step (2) is as follows: evaporate the solvent acetonitrile from reaction solution B under reduced pressure, wash the remaining mixture thoroughly three times with diethyl ether, evaporate the solvent under reduced pressure and dry thoroughly to obtain an ionic liquid with the structure shown in formula (Ⅰ-Ⅰ) or (Ⅰ-Ⅱ) or (Ⅰ-Ⅲ) or (Ⅰ-Ⅳ) or (Ⅰ-Ⅴ) or (Ⅰ-Ⅵ).

5. The method for preparing nano-metal particles with precisely controlled morphology as described in claim 2, characterized in that: In step (1), the volume of acetonitrile used is recorded as 10~20 mL / g of the mass of the intermediate product shown in formula II or III or IV or V or VI or VII.

6. The method for preparing nano-metal particles with precisely controlled morphology as described in claim 2, characterized in that: The halogen in the halogenated compound R2 in step (2) should be chlorine, bromine or iodine; R2 in the halogenated compound R2 is selected from heptyl or butyl.

7. The method for preparing nano-metal particles with precisely controlled morphology as described in claim 2, characterized in that: The volume of acetonitrile used in step (2) is 1~5 mL / g, expressed as the mass of the halogenated product R2.

8. The method for preparing nano-metal particles with precisely controlled morphology as described in claim 2, characterized in that: The intermediate products represented by formula II, III, IV, V, VI, or VII are prepared according to the following steps: Imidazole, morpholine, piperidine, pyrrolidine, pyrazole, or tertiary amine are mixed with sodium hydroxide, potassium hydroxide, or potassium carbonate and acetonitrile. The mixture is stirred at room temperature for 3 hours to obtain reaction solution C. Halogen R1 is added to reaction solution C, and the reaction is continued under reflux for 48 hours to obtain reaction solution D. Deionized water is added to the reaction solution, and the mixture is extracted with dichloromethane. The organic phase is collected, thoroughly dried with anhydrous sodium sulfate, and finally the solvent is removed by vacuum distillation to obtain the intermediate product shown in formula II, III, IV, V, VI, or VII.

9. The method for preparing nano-metal particles with precisely controlled morphology as described in claim 8, characterized in that: The ratio between the amount of imidazole, morpholine, piperidine, pyrrolidine, pyrazole, or tertiary amine and the amount of sodium hydroxide, potassium hydroxide, or potassium carbonate is 1:1 to 3; the volume of acetonitrile used is 1 mmol / 1 to 3 mL, expressed as the amount of sodium hydroxide, potassium hydroxide, or potassium carbonate; the halogen in the halogenated compound R1 is chlorine, bromine, or iodine; and R1 in the halogenated compound R1 is selected from heptyl or butyl.

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