Method for preparing doped nanocrystals using amino polymer reverse miniemulsion colloid

Abstract

The present invention relates to the fields of reverse miniemulsion colloids and sintering treatments, and particularly to a method for preparing doped nanocrystals using amino polymer reverse miniemulsion colloids. A reverse miniemulsion with an amino polymer solution as the dispersed phase is first prepared, followed by a reverse miniemulsion with a matrix metal salt solution as the dispersed phase. A doped nanomaterial precursor is then formed within the amino polymer reverse miniemulsion droplets, ultimately producing the doped nanomaterial. The amino polymer selectively adsorbs metal ions to form a reverse miniemulsion of the doped nanomaterial precursor, which is then concentrated and sintered to produce the doped nanocrystalline material. This method for preparing doped nanocrystals has potential applications in photovoltaic conversion, battery materials, and catalysis.

Description

Technical Field

[0001] The invention relates to the fields of reverse miniemulsion colloid, sintering treatment and the like, and in particular to a method for preparing doped nanocrystals by utilizing amino polymer reverse miniemulsion colloid. Background Art

[0002] Doping is the mixing of multiple substances together, and doping is usually used to change the chemical composition of a material. In the fields of chemical engineering, materials, etc., doping usually refers to the purposeful addition of a small amount of other elements or compounds into a material or matrix in order to improve the performance of a certain material or substance. Doping can make materials and matrices produce specific electrical, magnetic, and optical properties, thereby giving them specific value or use. Doping can change the electronic structure of a material, modulate its band gap size, conductivity, magnetism, photocatalytic properties, etc., so that the performance of the material can be improved to meet new application requirements. Therefore, doping has been widely used in the fields of materials science, electronics, chemistry, and energy. Doping is widely used in materials science and engineering in the fields of polymer materials, metal materials, semiconductor materials, battery materials, catalytic materials, etc.

[0003] Doping can be categorized as ion doping, atomic doping, vacancy doping, and chemical doping, depending on the chemical composition and processing method of the material. Chemical doping includes deposition, solution, and vapor phase methods. The impurities formed by chemical methods have a specific crystal structure and distribution pattern, representing ordered doping. However, existing doping methods have limitations in preparing nanoparticle-sized doped materials. For example, particles larger than 100 nanometers are prone to agglomeration. Summary of the Invention

[0004] The invention aims to prepare doped nanocrystalline materials by using an inverse miniemulsion colloid with an aqueous amino polymer as a dispersed phase.

[0005] The above method is carried out according to the following steps:

[0006] (1) Preparation of reverse miniemulsion with amino polymer solution as dispersed phase:

[0007] At room temperature, a quantitative amino polymer aqueous solution of a certain concentration and a quantitative oily solution are mixed, and then crushed under ice water cooling conditions in a high-speed shearing machine. After the high-speed shearing machine crushes for a fixed time, an inverse miniemulsion colloid with the amino polymer solution as the dispersed phase can be obtained.

[0008] The amino polymer is monomethoxypolyethylene oxide amine or aminopolyethylene glycol, both of which are commercially available products with a relative mass average molecular weight of 2000-5000; and the oily solvent is C4.

[0009] The mass concentration of the amino polymer aqueous solution is 1-3%, and the mass ratio of the amino polymer aqueous solution to the oily solvent is 10:50-80.

[0010] The speed of the high-speed shearing machine is 20,000 rpm, the crushing time is 5 minutes, and the temperature is controlled at 10°C.

[0011] (2) Preparation of reverse miniemulsion with matrix metal salt solution as dispersed phase:

[0012] Under room temperature, a quantitative aqueous solution of one or more soluble metal salts, an emulsifier and an oily solvent are mixed and transferred to an ultrasonic bio-pulverizer for pulverization for a fixed time to complete the preparation of a miniemulsion with the matrix metal salt solution as the dispersed phase.

[0013] Among them, one or more soluble metal salts are aqueous solutions of soluble nitric acid, hydrochloric acid or sulfate of iron, chromium, cadmium or copper; the oily solvent is C4; and the emulsifier is Span80.

[0014] The mass concentration of the soluble metal salt aqueous solution is 1-3%, and the mass ratio of the soluble metal salt aqueous solution, the emulsifier and the oily solvent is 10:0.3:50.

[0015] The ultrasonic bio-crusher was used at 250W power and the crushing time was 5 minutes.

[0016] (3) Formation of doped nanomaterial precursors in amino polymer reverse miniemulsion droplets:

[0017] At room temperature, a certain concentration of water-soluble doping metal salt is added at one time to the amino polymer reverse miniemulsion prepared in the quantitative step (1), and the mixture is moved to an ultrasonic bio-crusher and crushed for a fixed time; then the reverse miniemulsion of the matrix metal salt solution in the quantitative step (2) is added dropwise to the amino polymer reverse miniemulsion to which the water-soluble doping metal salt has been added, and the mixture is crushed again for a fixed time to complete the preparation of the doped nanomaterial precursor in the amino polymer reverse miniemulsion droplets.

[0018] The water-soluble doping metal salt is a functional nitro salt, such as strontium nitrate, samarium nitrate, or europium nitrate, with a mass concentration of 1-3%. The mass ratio of the water-soluble doping metal salt, the reverse miniemulsion prepared in step (1), and the reverse miniemulsion prepared in step (2) is 0.1-0.5:50:10, and the addition rate is 10% of the mass of the water-soluble doping metal salt per minute. The ultrasonic biopulverizer is used at a power of 250W for 5 minutes each time.

[0019] (4) Preparation of doped nanomaterials

[0020] The polymer inverse miniemulsion of the doped nanomaterial precursor is stirred under heating and concentrated into a paste. The paste is transferred to a crucible and sintered for a certain period of time to obtain a solid powder, which is the doped nanomaterial.

[0021] The heating temperature is 60-70°C, and the emulsion is concentrated to 20-30% of the original weight; the sintering temperature is 400-500°C, and the time is 2-3 hours.

[0022] The present invention utilizes amino polymers to selectively adsorb metal ions to form a reverse miniemulsion of a doped nanomaterial precursor. This process then uses concentration and sintering to produce doped nanocrystals. This method for preparing doped nanocrystals has potential applications in photovoltaic conversion, battery materials, and catalysis. The invention offers the following advantages:

[0023] The amino groups at the end of water-soluble amino polymers are used to selectively adsorb metal ions to form reverse miniemulsion colloidal particles; the amino polymer-supported doped nanomaterial precursor in the reverse miniemulsion colloidal particles maintains uniform and stable doped nanocrystal particle size during the sintering process, and is not easy to agglomerate. The average crystal particle size is 10-30 nanometers and has good dispersibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is the TEM image of the inverse miniemulsion in step (3) of Example 1.

[0025] Figure 2 This is the SEM image of the doped nanomaterial in step (4) of Example 1. DETAILED DESCRIPTION

[0026] The present invention will be further described in detail below in conjunction with the embodiments.

[0027] Example 1

[0028] (1) Preparation of reverse miniemulsion with amino polymer solution as dispersed phase:

[0029] At room temperature, 10 grams of a 1% aqueous solution of methoxypolyethylene oxide (polymer relative mass-average molecular weight: 2000) and 50 grams of C4 solution were mixed and pulverized on a high-speed shear at 20,000 rpm under ice-water cooling for 5 minutes at a temperature of 10°C. This yielded an inverse miniemulsion with the amino polymer solution as the dispersed phase. The particles in the inverse miniemulsion had a Z-average particle size of 200 nanometers and a dispersion index (PDI) of 0.15.

[0030] (2) Preparation of reverse miniemulsion with matrix metal salt solution as dispersed phase:

[0031] At room temperature, 10 grams of a 1% total salt solution (ferric sulfate and cadmium nitrate, with a 1:1 molar ratio) was mixed with 0.3 grams of Span 80 emulsifier and 50 grams of C4 solvent. The mixture was then transferred to a 250W ultrasonic biopulverizer and pulverized for 5 minutes. This resulted in a reverse miniemulsion with the matrix metal salt solution as the dispersed phase. The colloidal particles in the reverse miniemulsion had a Z-average particle size of 250 nanometers and a dispersion index (PDI) of 0.20.

[0032] (3) Formation of doped nanomaterial precursors in amino polymer reverse miniemulsion droplets:

[0033] At room temperature, 0.1 g of a 1% aqueous solution of strontium nitrate was added all at once to 50 g of the amino polymer reverse miniemulsion prepared in step (1). The mixture was then pulverized in an ultrasonic bio-mill at 250 W for 5 minutes. Then, 10 g of the reverse miniemulsion containing the matrix metal salt solution prepared in step (2) was added dropwise to the amino polymer reverse miniemulsion to which the water-soluble doping metal salt had been added. The mixture was again pulverized in an ultrasonic bio-mill at 250 W for 5 minutes, completing the preparation of the doped nanomaterial precursor within the amino polymer reverse miniemulsion droplets. The reverse miniemulsion colloidal particles had a Z-average particle size of 160 nm and a dispersion index (PDI) of 0.10. Figure 1 This is a TEM image of the inverse miniemulsion in step (3). The image shows that the precursor particle size is 1-2 nanometers.

[0034] (4) Preparation of doped nanomaterials

[0035] The polymer inverse miniemulsion of the doped nanomaterial precursor in the method of step (3) is stirred under heating at 60°C and concentrated to 12.02 grams of a paste. The paste is transferred to a crucible and sintered at a temperature of 400°C for 3 hours. The resulting solid powder is the strontium-doped iron cadmium oxysalt nanomaterial. X-ray diffraction analysis shows that the doped nanomaterial meets the characteristic diffraction peaks of the PDF standard card, and the secondary diffraction peak of the strontium-doped iron cadmium oxysalt nanocrystal is slightly shifted to the right; the nanocrystal particle size is calculated based on the half-width of the diffraction peak to be 35 nanometers. Figure 2 This is the SEM image of the doped nanomaterial in step (4) of Example 1.

[0036] Example 2

[0037] (1) Preparation of reverse miniemulsion with amino polymer solution as dispersed phase:

[0038] At room temperature, 10 g of a 3% aqueous solution of aminopolyethylene glycol (polymer relative mass-average molecular weight of 5000) and 80 g of C4 solution were mixed and pulverized on a high-speed shear at 20,000 rpm under ice-water cooling for 5 minutes at a temperature of 10°C. This yielded an inverse miniemulsion with the aminopolymer solution as the dispersed phase. The particles in the inverse miniemulsion had a Z-average particle size of 100 nm and a dispersion index (PDI) of 0.10.

[0039] (2) Preparation of reverse miniemulsion with matrix metal salt solution as dispersed phase:

[0040] At room temperature, a mixture of 10 g of a 3% cadmium sulfate aqueous solution, 0.3 g of Span 80 emulsifier, and 50 g of C4 solvent was transferred to a 250W ultrasonic biopulverizer and pulverized for 5 minutes. This completed the preparation of a miniemulsion with the matrix metal salt solution as the dispersed phase. The Z-average particle size of the inverse miniemulsion colloidal particles was 150 nm, and the dispersion index (PDI) was 0.20.

[0041] (3) Formation of doped nanomaterial precursors in amino polymer reverse miniemulsion droplets:

[0042] At room temperature, 0.5 g of a 3% samarium nitrate aqueous solution was added all at once to 50 g of the amino polymer reverse miniemulsion prepared in step (1). The mixture was then pulverized in an ultrasonic bio-mill at 250 W for 5 minutes. Then, 10 g of the matrix metal salt solution in step (2) was dropwise added to the amino polymer reverse miniemulsion to which the water-soluble doping metal salt had been added. The mixture was again pulverized in an ultrasonic bio-mill at 250 W for 5 minutes, completing the preparation of the doped nanomaterial precursor within the amino polymer reverse miniemulsion droplets. The reverse miniemulsion colloidal particles had a Z-average particle size of 120 nm and a dispersion index (PDI) of 0.08.

[0043] (4) Preparation of doped nanomaterials

[0044] The polymer inverse miniemulsion of the doped nanomaterial precursor in the method of step (3) is stirred under heating at 70°C and concentrated to 18.15 grams of a paste. The paste is transferred to a crucible and sintered at a temperature of 500°C for 2 hours. The resulting solid powder is the europium-doped cadmium oxide salt nanomaterial. X-ray diffraction analysis shows that the doped nanomaterial meets the characteristic diffraction peaks of the PDF standard card, and the spectrum shows a right-shifted secondary diffraction peak of the europium-doped cadmium oxide salt nanocrystals; the nanocrystal particle size is calculated to be 28 nanometers based on the half-maximum width of the diffraction peak.

[0045] Example 3

[0046] (1) Preparation of reverse miniemulsion with amino polymer solution as dispersed phase:

[0047] At room temperature, 10 grams of a 2% aqueous solution of aminopolyethylene glycol (polymer relative mass-average molecular weight 3000) and 60 grams of C4 solution were mixed and pulverized on a high-speed shear at 20,000 rpm under ice-water cooling for 5 minutes at a temperature of 10°C. This yielded an inverse miniemulsion with the aminopolymer solution as the dispersed phase. The inverse miniemulsion had a Z-average particle size of 150 nanometers and a dispersion index (PDI) of 0.09.

[0048] (2) Preparation of reverse miniemulsion with matrix metal salt solution as dispersed phase:

[0049] At room temperature, a mixture of 10 g of a 2% copper chloride solution, 0.3 g of Span emulsifier, and 50 g of C4 solvent was transferred to a 250W ultrasonic biopulverizer and pulverized for 5 minutes. This resulted in a miniemulsion with the matrix metal salt solution as the dispersed phase. The colloidal particles in the inverse miniemulsion had a Z-average particle size of 200 nm and a dispersion index (PDI) of 0.15.

[0050] (3) Formation of doped nanomaterial precursors in amino polymer reverse miniemulsion droplets:

[0051] At room temperature, 0.3 g of a 2% aqueous europium nitrate solution was added all at once to 50 g of the amino polymer reverse miniemulsion prepared in step (1). The mixture was then pulverized in an ultrasonic bio-mill at 250 W for 5 minutes. Then, 10 g of the reverse miniemulsion containing the matrix metal salt solution prepared in step (2) was added dropwise to the amino polymer reverse miniemulsion to which the water-soluble doping metal salt had been added. The mixture was again pulverized in an ultrasonic bio-mill at 250 W for 5 minutes, completing the preparation of the doped nanomaterial precursor within the amino polymer reverse miniemulsion droplets. The reverse miniemulsion colloidal particles had a Z-average particle size of 180 nm and a dispersion index (PDI) of 0.12.

[0052] (4) Preparation of doped nanomaterials

[0053] In step (3), the polymer inverse miniemulsion of the doped nanomaterial precursor in the method is stirred under heating at 65° C. and concentrated to 15.50 g of a paste. The paste is transferred to a crucible and sintered at a temperature of 450° C. for 2.5 hours. The resulting solid powder is the europium-doped copper oxide salt nanomaterial. X-ray diffraction analysis shows that the doped nanomaterial meets the characteristic diffraction peaks of the PDF standard card, and the spectrum shows a right-shifted secondary diffraction peak of the europium-doped copper oxide salt nanocrystals; the nanocrystal particle size is calculated to be 30 nanometers based on the half-maximum width of the diffraction peak.

[0054] The above description of the embodiments is intended to facilitate understanding and application of the present invention by those skilled in the art. It will be apparent that those skilled in the art can readily make various modifications to these embodiments and apply the general principles described herein to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the embodiments described herein, and modifications made by those skilled in the art based on the present disclosure are intended to fall within the scope of protection of the present invention.

Claims

1. A method for preparing doped nanocrystals using amino polymer reverse miniemulsion colloid, characterized in that: The method steps are as follows: (1) Preparation of reverse miniemulsion with amino polymer solution as dispersed phase: At room temperature, the amino polymer aqueous solution and the oily solution are mixed and then crushed under ice water cooling in a high-speed shearing machine to obtain an inverse miniemulsion colloid with the amino polymer solution as the dispersed phase; (2) Preparation of reverse miniemulsion with matrix metal salt solution as dispersed phase: Under room temperature, a mixture of an aqueous solution of a metal salt, an emulsifier, and an oily solvent is transferred to an ultrasonic bio-pulverizer and pulverized for a fixed time to complete the preparation of a reverse miniemulsion with the matrix metal salt solution as the dispersed phase; The metal salt is one or more of a soluble nitric acid, hydrochloric acid or sulfate aqueous solution of iron, chromium, cadmium or copper; (3) Formation of doped nanomaterial precursors in amino polymer reverse miniemulsion droplets: At room temperature, a water-soluble doped metal salt aqueous solution is added to the amino polymer reverse miniemulsion prepared in step (1) at one time, and the mixture is moved to an ultrasonic bio-pulverizer and pulverized for a fixed time; then the reverse miniemulsion of the matrix metal salt solution in step (2) is added dropwise to the amino polymer reverse miniemulsion to which the water-soluble doped metal salt has been added, and the mixture is pulverized again for a fixed time to complete the preparation of the doped nanomaterial precursor in the amino polymer reverse miniemulsion droplets; (4) Preparation of doped nanomaterials The polymer inverse miniemulsion of the doped nanomaterial precursor in step (3) is stirred under heating and concentrated into a paste; the paste is transferred to a crucible and sintered to obtain the doped nanomaterial.

2. The method for preparing doped nanocrystals using amino polymer reverse miniemulsion colloid according to claim 1, wherein: In step (1), the amino polymer is monomethoxypolyethylene oxide amino or amino polyethylene glycol, and the relative mass average molecular weight is 2000-5000; the oily solvent is C4.

3. The method for preparing doped nanocrystals using amino polymer reverse miniemulsion colloid according to claim 1, characterized in that: The mass concentration of the amino polymer aqueous solution in step (1) is 1-3%, and the mass ratio of the amino polymer aqueous solution to the oily solvent is 10:50-80.

4. The method for preparing doped nanocrystals using amino polymer reverse miniemulsion colloid according to claim 1, wherein: Step (1) The speed of the high-speed shearing machine is 20,000 rpm, the crushing time is 5 minutes, and the temperature is controlled at 10°C.

5. The method for preparing doped nanocrystals using amino polymer reverse miniemulsion colloid according to claim 1, wherein: In step (2), the oily solvent is C4; and the emulsifier is Span80.

6. The method for preparing doped nanocrystals using amino polymer reverse miniemulsion colloid according to claim 1, characterized in that: In step (2), the mass concentration of the metal salt aqueous solution is 1-3%, and the mass ratio of the soluble metal salt aqueous solution, the emulsifier and the oily solvent is 10:0.3:50; the ultrasonic bio-crusher has a power of 250W and the crushing time is 5 minutes each time.

7. The method for preparing doped nanocrystals using amino polymer reverse miniemulsion colloid according to claim 1, characterized in that: The water-soluble doping metal salt in step (3) is strontium nitrate, samarium nitrate or europium nitrate, and the mass concentration of the water-soluble doping metal salt aqueous solution is 1-3%; the mass ratio of the water-soluble doping metal salt, the reverse miniemulsion prepared in step (1) and the reverse miniemulsion prepared in step (2) is 0.1-0.5:50:10, and the dropping speed is 10% of the mass of the water-soluble doping metal salt per minute; the ultrasonic biopulverizer is 250W power and the pulverization is 5 minutes each time.

8. The method for preparing doped nanocrystals using amino polymer reverse miniemulsion colloid according to claim 1, characterized in that: In step (4), the heating temperature is 60-70°C, and the emulsion is concentrated to 20-30% of the original weight; the sintering temperature is 400-500°C, and the sintering time is 2-3 hours.

9. A doped nanocrystal prepared by the method according to any one of claims 1 to 8.

Images