Preparation method of metal nanoparticles with accurately regulated and controlled morphology

Abstract

The invention discloses a preparation method of metal nanoparticles with accurate morphology regulation and control. According to the preparation method, an electrolyte is electrolyzed by adopting a conductive anode material, and the morphology of nano metal particles electrodeposited on a conductive cathode is accurately regulated and controlled by adjusting the types of additives in the electrolyte. The invention further provides a preparation method of the additive in the electrolyte, and the nano metal particles in the shapes of spheres, flowers, urchins, sheets, cubes and the like can be obtained through electro-deposition by controlling the adding types of the additive, and the shapes of the nano metal particles are accurately regulated and controlled. The synthesized ionic liquid capable of being used for the electrolyte additive serves as an electro-deposition electrolyte additive for accurately regulating and controlling the morphology of nano-metal particles, the morphology of the nano-metal particles prepared through electro-deposition can be accurately regulated and controlled, production steps of the nano-metal particles with different morphologies are reduced, and the production cost is reduced; meanwhile, the method has the characteristics of low energy consumption, high yield, simple process, safety, environment friendliness and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of electrochemistry, and in particular relates to a method for preparing metal nanoparticles with precisely controlled morphology. Background Art

[0002] In recent years, with the development of various novel properties and application fields of nanometal particles, the field of nanometal particles has been booming and has become the basic material for preparing various new key functional materials. The preparation of nanometal particles mainly includes chemical and physical methods. The chemical method includes high-temperature pyrolysis, liquid phase reduction, etc. The latter includes hydrothermal, solvent thermal and other methods. Among them, the liquid phase reduction method can roughly control the morphology and size of the particles, and requires a large amount of surfactant to be added, and a large amount of wastewater is generated. High-temperature pyrolysis and arc evaporation condensation methods are also commonly used methods for synthesizing metal particles and regulating their morphology, but they are both energy-intensive, and nanometal particles often have a wide particle size distribution. The nanometal particles prepared by physical crushing and evaporation condensation methods such as ball milling and crushing are large in size and unevenly distributed, and have many defects. Therefore, the chemical method for preparing nanometal particles has low energy consumption, simple process, easy control of product morphology and good uniformity.

[0003] Metal electrodeposition is a technology that uses electrochemical principles to deposit one or more metal ions in an electrolyte onto the cathode surface. By controlling the electrodeposition parameters and electrolyte composition, nanoparticles of different metals and morphologies can be prepared by electrodeposition. However, there are currently very few reports on the use of electrodeposition to prepare and precisely control the morphology of nanometal particles, and they are limited to block, flake and powder morphologies, making it difficult to adapt to multifunctional application requirements.

[0004] CN201710399752.3 uses aqueous solution electrolysis of metal salts to prepare finer Cu, Fe, Co and Ni particles, but the energy consumption is high and the effective regulation of the morphology of nano-metal particles is not achieved. CN201710098703.6 uses graphite felt or carbon felt as an anode to obtain powdered metal by electrodeposition, but the regulation of the morphology of the metal powder is not achieved, and the production cost is very high. CN201911117064.9 discloses a method for preparing metal nanoparticles by continuous electrochemical deposition, which realizes the continuous preparation and stripping of Ag, Cu, Au, Co and Ni particles, but cannot accurately control the morphology of nano-metal particles. Therefore, how to achieve accurate and effective regulation of the morphology of nano-metal particles has always been a research difficulty in the field of nano-metal particle preparation. Summary of the invention

[0005] In order to solve the problem that the morphology of existing electrodeposited nanometal particles is difficult to accurately and effectively control, the present invention uses ionic liquid as an additive to induce precise control of the morphology of electrodeposited nanometal particles, and regulates and prepares nanometal particles in shapes such as spheres, flowers, sea urchins, flakes and cubes.

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

[0007] In order to achieve the above object, the present invention first provides an ionic liquid electrodeposition electrolyte ionic liquid additive having a structure as shown in formula (Ⅰ-Ⅰ) or (Ⅰ-Ⅱ) or (Ⅰ-Ⅲ) or (Ⅰ-Ⅳ) or (Ⅰ-Ⅴ) or (Ⅰ-Ⅵ);

[0008]

[0009] The method for preparing the ionic liquid additive having a structure represented by formula (Ⅰ-Ⅰ) or (Ⅰ-Ⅱ) or (Ⅰ-Ⅲ) or (Ⅰ-Ⅳ) or (Ⅰ-Ⅴ) or (Ⅰ-Ⅵ) of the present invention is specifically prepared according to the following steps:

[0010] (1) dissolving the intermediate product represented by formula II, III, IV, V, VI or VII in an acetonitrile solution to obtain a reaction solution A;

[0011] (2) dropping an acetonitrile solution of the halide R2 into a reaction solution A, reacting at 60 to 90° C. for 12 to 24 hours to obtain a reaction solution B, and post-treating to obtain an ionic liquid having a structure represented by formula (I-I) or (I-II) or (I-III) or (I-IV) or (I-V) or (I-VI); the ratio between the amount of the intermediate product represented by formula II or III or IV or V or VI or VII and the amount of the feed material of the halide R2 is 1:1.0 to 1.5;

[0012]

[0013] Furthermore, in step (1), the volumetric amount of acetonitrile used is 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 halide R2 should be chlorine, bromine or iodine.

[0015] Furthermore, in step (2), R2 in the halide 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 amount of acetonitrile is 1 to 5 mL / g based on the mass of the halide R2.

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

[0018] The intermediate product represented by formula II, III, IV, V, VI or VII of the present invention is prepared specifically according to the following steps:

[0019] Imidazole, morpholine, piperidine, pyrrolidine, pyrazole, or tertiary amine, sodium hydroxide, potassium hydroxide, potassium carbonate, and acetonitrile are mixed, and the mixture is stirred at room temperature for 3 hours to obtain reaction solution C. Halide R1 is added to reaction solution C, and the reaction is continued under reflux conditions 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, and the mixture is fully dried over anhydrous sodium sulfate. Finally, the solvent is evaporated under reduced pressure to obtain an intermediate product represented by formula II, III, IV, V, VI, or VII; the ratio between the amount of the imidazole, morpholine, piperidine, pyrrolidine, pyrazole, or tertiary amine and the amount of the feed material of sodium hydroxide, potassium hydroxide, or potassium carbonate is 1:1-3; the volume amount of the acetonitrile is recorded as 1mmol / 1-3mL based on the amount of the substance of sodium hydroxide, potassium hydroxide, or potassium carbonate; the halogen in the halide R1 is chlorine, bromine, or iodine; and R in the halide R1 is an alkane, aromatic hydrocarbon, ester, ether, or carboxylic acid with a carbon chain length of 2-15;

[0020] The target product is characterized by nuclear magnetic resonance hydrogen spectrum (NMR) and infrared absorption spectrum (FT-IR). The electrochemistry of the obtained ionic liquid additive is characterized by using Swiss Metrohm electrochemical workstation AutoLab302N. The ionic liquid additive prepared by the present invention has good electrochemical stability and can be used as an electrolyte additive to induce precise control of the morphology of electrodeposited nanometal particles.

[0021] In order to achieve the above-mentioned purpose of precisely controlling the morphology of electrodeposited nanometal particles, the present invention adopts the following technical solution: two conductive electrodes are placed side by side in an electrolyte containing an ionic liquid additive, the two conductive electrodes are respectively connected to the positive and negative poles of a DC bias power supply, and a bias voltage is applied at room temperature to obtain nanometal particles with precisely controlled morphology.

[0022] Among them, the conductive electrode is one of indium tin oxide conductive glass, fluorine-doped tin oxide conductive glass, conductive silver plate, or dotted nickel plate, and the distance between the two conductive electrodes is 1-10cm; the applied bias voltage is 1-10V; the shape of the nano-metal particles with precisely controlled morphology is one of spherical, flower-shaped, sea urchin-shaped, flake-shaped, cubic, etc.

[0023] In a specific embodiment of the present invention, the ionic liquid additive is one or more combinations of the structures shown in formula (Ⅰ-Ⅰ) or (Ⅰ-Ⅱ) or (Ⅰ-Ⅲ) or (Ⅰ-Ⅳ) or (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 dosage of the ionic liquid additive is 0.1-5g / mL based on the volume of the electrolyte solvent.

[0024] In a specific embodiment of the present invention, the electrolyte should also contain one or a combination of gold, silver, copper, iron, zinc, nickel, aluminum, and magnesium salts necessary for preparing nanometal particles; the anion of the gold, silver, copper, iron, zinc, nickel, aluminum, or magnesium salt is one of sulfate, sulfite, nitrate, perchlorate, hypochlorite, chloride anion, bromide anion, or iodide anion.

[0025] The ionic liquid with a structure shown in formula (Ⅰ-Ⅰ) or (Ⅰ-Ⅱ) or (Ⅰ-Ⅲ) or (Ⅰ-Ⅳ) or (Ⅰ-Ⅴ) or (Ⅰ-Ⅵ) prepared in the present invention can be used as an additive to induce metal electrodeposition to precisely control the morphology of nano-metal particles.

[0026] The present invention can accurately control the morphology of nano-metal particles by electrodeposition of an electrolyte containing an ionic liquid additive, so as to prepare nano-metal particles in the shape of spheres, flowers, sea urchins, sheets or cubes.

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

[0028] The present invention synthesizes an ionic liquid that can be used as an electrolyte additive, which can be used as an electrodeposition electrolyte additive for accurately controlling the morphology of nanometal particles. It can accurately control the morphology of nanometal particles prepared by electrodeposition, which is beneficial to reducing the production steps of nanometal particles with different morphologies and reducing production costs. At the same time, it has the characteristics of low energy consumption, high yield, simple process, safety and environmental protection. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0030] Figure 2 : The morphology of the electrodeposited silver metal particles in Example 8 of the present invention;

[0031] Figure 3 : The morphology of the electrodeposited silver metal particles in Example 9 of the present invention;

[0032] Figure 4 : The morphology of the electrodeposited silver metal particles in Example 10 of the present invention;

[0033] Figure 5 : The morphology of the electrodeposited silver metal particles in Example 11 of the present invention;

[0034] Figure 6 : The morphology of the electrodeposited silver metal particles in Example 12 of the present invention;

[0035] Figure 7 : The morphology of the electrodeposited silver metal particles in Example 13 of the present invention; DETAILED DESCRIPTION

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

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

[0038] Example 11, Synthesis of 3-Diheptylimidazole Bromide

[0039] At 25°C, imidazole (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 reaction mixture was subjected to rotary evaporation to remove the volatile solvent CH3CN, CH2Cl2 was added to the residue, extracted three times with water, and the organic phase was thoroughly dried with anhydrous Na2SO4. The collected organic phase filtrate was subjected to rotary evaporation to remove the solvent, and then thoroughly washed three times with ether. The solid product obtained by removing the ether was finally dried in a dynamic vacuum oven at 45°C for 24 h to obtain the intermediate product shown in formula (II). At 25°C, the intermediate product shown in formula (II) (20.0 mmol) and 1-bromoheptane (20.0 mmol) were continued to react in CH3CN (20.0 mL) under reflux for 48 h. The reaction mixture was subjected to rotary evaporation to remove the volatile solvent CH3CN, and then thoroughly washed three times with ether. The solid product obtained by removing the ether was finally dried in a dynamic vacuum oven at 45°C for 24 h to obtain a brown-red viscous liquid product in which R1 and R2 shown in formula (Ⅰ-Ⅰ) both have a carbon chain length of 7 and halogen X is bromine, and the yield is 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 reaction mixture was subjected to rotary evaporation to remove the volatile solvent CH3CN, CH2Cl2 was added to the residue, extracted three times with water, and the organic phase was thoroughly dried with anhydrous Na2SO4. The collected organic phase filtrate was subjected to rotary evaporation to remove the solvent, and then thoroughly washed three times with ether. The solid product obtained by removing the ether was finally dried in a dynamic vacuum oven at 45°C for 24 h to obtain the intermediate product shown in formula (III). At 25°C, the intermediate product shown in formula (III) (20.0 mmol) and 1-bromoheptane (20.0 mmol) were continued to react in CH3CN (20.0 mL) under reflux for 48 h. The reaction mixture was subjected to rotary evaporation to remove the volatile solvent CH3CN, and then washed thoroughly three times with ether. The solid product obtained by removing the ether was finally dried in a dynamic vacuum oven at 45°C for 24 hours to obtain a white powder solid product represented by formula (Ⅰ-Ⅱ) in which both R1 and R2 have a carbon chain length of 7 and halogen X is bromine, with a yield of 78.9%.

[0043]

[0044] Example 31, Synthesis of 1-Diheptylpiperidinium Bromide

[0045] At 25°C, piperidine (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 conditions for 48 h. The reaction mixture was subjected to rotary vacuum evaporation to remove the volatile solvent CH3CN, CH2Cl2 was added to the residue, extracted three times with water, and the organic phase was thoroughly dried with anhydrous Na2SO4. The collected organic phase filtrate was subjected to rotary vacuum evaporation to remove the solvent, and then thoroughly washed three times with ether. The solid product obtained by removing the ether was finally dried in a dynamic vacuum oven at 45°C for 24 h to obtain the intermediate product shown in formula (IV). At 25°C, the intermediate product shown in formula (IV) (20.0 mmol) and 1-bromoheptane (20.0 mmol) were continued to react in CH3CN (20.0 mL) under reflux conditions for 48 h. The reaction mixture was subjected to rotary evaporation to remove the volatile solvent CH3CN, and then thoroughly washed three times with ether. The solid product obtained by removing the ether was finally dried in a dynamic vacuum oven at 45°C for 24 hours to obtain a white powder solid product represented by formula (I-III) in which both R1 and R2 have a carbon chain length of 7 and halogen X is bromine, with a yield of 92.7%.

[0046]

[0047] Example 41 Synthesis of 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 reaction mixture was subjected to rotary evaporation to remove the volatile solvent CH3CN, CH2Cl2 was added to the residue, extracted three times with water, and the organic phase was thoroughly dried with anhydrous Na2SO4. The collected organic phase filtrate was subjected to rotary evaporation to remove the solvent, and then thoroughly washed three times with ether. The solid product obtained by removing the ether was finally dried in a dynamic vacuum oven at 45°C for 24 h to obtain the intermediate product represented by formula (V). At 25°C, the intermediate product represented by formula (V) (20.0 mmol) and 1-bromoheptane (20.0 mmol) were continued to react in CH3CN (20.0 mL) under reflux for 48 h. The reaction mixture was subjected to rotary evaporation to remove the volatile solvent CH3CN, and then washed thoroughly three times with ether. The solid product obtained by removing the ether was finally dried in a dynamic vacuum oven at 45°C for 24 hours to obtain a white solid product represented by formula (I-IV) in which both R1 and R2 have a carbon chain length of 7 and halogen X is 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 reaction mixture was subjected to rotary evaporation to remove the volatile solvent CH3CN, CH2Cl2 was added to the residue, extracted three times with water, and the organic phase was thoroughly dried with anhydrous Na2SO4. The collected organic phase filtrate was subjected to rotary evaporation to remove the solvent, and then thoroughly washed three times with ether. The solid product obtained by removing the ether was finally dried in a dynamic vacuum oven at 45°C for 24 h to obtain the intermediate product shown in formula (VI). At 25°C, the intermediate product shown in formula (VI) (20.0 mmol) and 1-bromoheptane (20.0 mmol) were continued to react in CH3CN (20.0 mL) under reflux for 48 h. The reaction mixture was subjected to rotary evaporation to remove the volatile solvent CH3CN, and then washed thoroughly three times with ether. The solid product obtained by removing the ether was finally dried in a dynamic vacuum oven at 45°C for 24 hours to obtain a white solid product represented by formula (Ⅰ-Ⅴ) in which both R1 and R2 have a carbon chain length of 7 and halogen X is 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) of formula (VII) was reacted with 1-bromoheptane (20.0 mmol) in CH3CN (20.0 mL) under reflux conditions for 48 h. The reaction mixture was subjected to rotary evaporation to remove the volatile solvent CH3CN, and then washed thoroughly with ether three times. The solid product obtained by removing the ether was finally dried in a dynamic vacuum oven at 45°C for 24 h to obtain a product of formula (I-VI) with a carbon chain length of 4 for R1, a carbon chain length of 7 for R2, and a halogen X as a white solid powder, with a yield of 95.2%.

[0055]

[0056] Example 7

[0057] The present embodiment provides an electrodeposition device for precisely controlling the morphology of electrodeposited nano-metal particles, which includes two conductive electrodes 1 and 3 arranged in parallel and correspondingly 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 an ionic liquid additive, a metal salt and a solvent is placed in the electrolytic cell, and the conductive surfaces of the two conductive electrodes (indium tin oxide glass) 1 and 3 are placed relatively parallel to each other, serving as an anode and a cathode respectively.

[0058] Example 8

[0059] This embodiment provides a technical solution for precisely controlling the morphology of electrodeposited nano-metal particles into flakes. 10 to 50 parts of an ionic liquid in which R1 and R2 shown in formula (I-I) are both carbon chain lengths of 7 and halogen X is bromine are dissolved in a solution of 2 to 10 parts of silver nitrate and 20 to 50 parts of dimethyl sulfoxide, and the mixture is stirred thoroughly. The electrodeposition electrolyte formed above is placed in an electrolytic cell, two conductive electrodes with a thickness of 0.5 mm are taken, the distance between them is 5 cm, a bias voltage of 2 V is applied, and flake nanoparticles of metallic silver are obtained at the cathode, such as Figure 2 shown.

[0060] Example 9

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

[0062] Example 10

[0063] This embodiment provides a technical solution for precisely controlling the morphology of electrodeposited nano-metal particles to be sea urchin-shaped, which is basically the same as that in Example 8, except that: the electrolyte 2 uses an ionic liquid in which R1 and R2 shown in formula (I-III) are both carbon chain lengths of 7 and halogen X is bromine. The sea urchin-shaped particles of metallic silver are obtained at the cathode, such as Figure 4 shown.

[0064] Embodiment 11

[0065] This embodiment provides a technical solution for precisely controlling the morphology of electrodeposited nano-metal particles into a flower shape, which is basically the same as that in Example 8, except that: the electrolyte 2 uses an ionic liquid in which R1 and R2 are both 7 carbon chain lengths and halogen X is bromine as shown in formula (I-IV). Flower-shaped particles of metallic silver are obtained at the cathode, such as Figure 5 shown.

[0066] Example 12

[0067] This embodiment provides a technical solution for precisely controlling the morphology of electrodeposited nano-metal particles to be cubic, which is basically the same as that in Example 8, except that: the electrolyte 2 uses an ionic liquid in which R1 and R2 are both 7 carbon chain lengths and halogen X is bromine as shown in formula (I-V). Cubic particles of metallic silver are obtained at the cathode, such as Figure 6 shown.

[0068] Embodiment 13

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

[0070] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

Claims

1. A method for preparing metal nanoparticles with precisely controlled morphology, characterized in that: By changing the type of additives in the electrodeposition electrolyte, electrodeposited nano-metal particles with different structural shapes can be obtained, including spherical, flower-shaped, sea urchin-shaped, flake-shaped and cubic shapes.

2. The method for preparing metal nanoparticles with precisely controlled morphology according to claim 1, characterized in that: The additive in the electrolyte is an ionic liquid having a structure as 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 metal nanoparticles with precisely controlled morphology according to claim 2, characterized in that: The ionic liquid additive in the electrolyte having a structure as shown in formula (Ⅰ-Ⅰ) or (Ⅰ-Ⅱ) or (Ⅰ-Ⅲ) or (Ⅰ-Ⅳ) or (Ⅰ-Ⅴ) or (Ⅰ-Ⅵ) is prepared according to the following steps: (1) dissolving the intermediate product represented by formula II, III, IV, V, VI or VII in an acetonitrile solution to obtain a reaction solution A; (2) dropping an acetonitrile solution of the halide R2 into a reaction solution A, reacting at 60 to 90° C. for 12 to 24 hours to obtain a reaction solution B, and post-treating to obtain an ionic liquid having a structure represented by formula (I-I) or (I-II) or (I-III) or (I-IV) or (I-V) or (I-VI); 4. The method for preparing metal nanoparticles with precisely controlled morphology according to claim 3, characterized in that: The ratio between the amount of the intermediate product represented by the formula II, III, IV, V, VI or VII and the amount of the feed material of the halide R2 is 1:1.0 to 1.

5.

5. The method for preparing metal nanoparticles with precisely controlled morphology as claimed in claim 3, characterized in that: The post-treatment method of the reaction liquid B in step (2) is: the solvent acetonitrile is evaporated from the reaction liquid B under reduced pressure, the remaining mixture is fully washed three times with diethyl ether, the solvent is evaporated under reduced pressure and fully dried to obtain an ionic liquid with a structure shown in formula (Ⅰ-Ⅰ) or (Ⅰ-Ⅱ) or (Ⅰ-Ⅲ) or (Ⅰ-Ⅳ) or (Ⅰ-Ⅴ) or (Ⅰ-Ⅵ).

6. The method for preparing metal nanoparticles with precisely controlled morphology as claimed in claim 3, characterized in that: In step (1), the volumetric amount of acetonitrile is 10-20 mL / g based on the mass of the intermediate product represented by formula II, III, IV, V, VI or VII.

7. The method for preparing metal nanoparticles with precisely controlled morphology according to claim 3, characterized in that: The halogen in the halide R2 in step (2) should be chlorine, bromine or iodine; R2 in the halide R2 should be an alkane, aromatic hydrocarbon, ester, ether or carboxylic acid with a carbon chain length of 2 to 15.

8. The method for preparing metal nanoparticles with precisely controlled morphology as claimed in claim 3, characterized in that: The volume amount of acetonitrile in step (2) is 1-5 mL / g based on the mass of the halide R2.

9. The method for preparing metal nanoparticles with precisely controlled morphology as claimed in claim 3, characterized in that: The intermediate product represented by formula II or III or IV or V or VI or VII is prepared specifically according to the following steps: imidazole or morpholine or piperidine or pyrrolidine or pyrazole or tertiary amine is mixed with sodium hydroxide or potassium hydroxide or potassium carbonate and acetonitrile, and the mixed solution is stirred at room temperature for 3 hours to obtain a reaction solution C; halide R1 is added to the reaction solution C, and the reaction is continued under reflux conditions for 48 hours to obtain a reaction solution D; deionized water is added to the reaction solution, and extracted with dichloromethane, the organic phase is collected, and it is fully dried over anhydrous sodium sulfate, and finally the solvent is evaporated under reduced pressure to obtain the intermediate product represented by formula II or III or IV or V or VI or VII.

10. The method for preparing metal nanoparticles with precisely controlled morphology according to claim 9, characterized in that: The ratio of the amount of the imidazole or morpholine or piperidine or pyrrolidine or pyrazole or tertiary amine to the amount of the sodium hydroxide or potassium hydroxide or potassium carbonate is 1:1-3; the volume amount of the acetonitrile is recorded as 1mmol / 1-3mL based on the amount of the sodium hydroxide or potassium hydroxide or potassium carbonate; the halogen in the halide R1 is chlorine, bromine or iodine; and R in the halide R1 is an alkane, aromatic hydrocarbon, ester, ether or carboxylic acid with a carbon chain length of 2-15.

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