A method for preparing yolk-shell structured mesoporous nanomaterial

Abstract

This invention discloses a method for preparing mesoporous nanomaterials with an egg yolk-shell structure. CTAB is dissolved in a mixed solvent of ethanol and water. Concentrated ammonia is added dropwise to adjust the solution to a weakly alkaline state. Then, 1,2-bis(triethoxysilyl)ethane is added dropwise, and the reaction is stirred. Following this, 3-aminopropyltrimethoxysilane is added dropwise, and the reaction is stirred again. The solid product is then separated, washed with alcohol, and vacuum dried to obtain amino-modified organosilicon nanospheres. These nanospheres are ground and dispersed in a mixed solvent of ethanol and water. CTAB and concentrated ammonia are added, followed by the addition of tetraethyl orthosilicate. The reaction is stirred, and then 1,2-bis(triethoxysilyl)ethane is added dropwise. The reaction mixture is then transferred to a reaction vessel and heated in an oven until it settles. After separation and purification, the final product is obtained. Compared with existing methods, this method is simple, economical, and efficient. The prepared nanomaterials can be used as nanoreactors to encapsulate noble metal nanoparticles, and the size of the nanoparticles can be precisely controlled by adjusting the size of the cavity.

Description

Technical Field

[0001] This invention relates to a mesoporous nanomaterial, specifically to a method for preparing an egg yolk-shell structured mesoporous nanomaterial, belonging to the field of nanomaterial technology. Background Technology

[0002] Egg yolk-shell structured mesoporous silica-based materials possess broad application potential in catalysis, energy, and drug delivery due to their low density, high specific surface area, highly ordered mesoporous shell, and large internal cavity. Currently, various methods are used to prepare egg yolk-shell structured nanomaterials.

[0003] Currently, methods for constructing organosilicon materials with cavity structures are mainly divided into two types: soft template method and hard template method. The soft template method utilizes the immiscibility of organic solvents with water to form droplets in an aqueous solution. The hydrolysis products of the organosilicon precursor condense around the organic droplets, and finally, the organic solvent is removed to prepare a silicon-based material with a cavity structure. For example: Journal of Colloid and Interface Science, 2016, 475:66-71. This method presents challenges in preparing materials with highly uniform cavity sizes. More importantly, the organic solvent used in the synthesis process is difficult to completely remove, limiting the material's application in the biomedical field. The hard template method introduces a heterogeneous material into the material and then removes it through certain means, thereby creating a cavity structure within the material. Phenolic resin and silica spheres are commonly used hard template materials. In the preparation of yolk-shell structured organosilicon nanomaterials, the main method for removing phenolic resin is to dissolve it with organic solutions such as acetone. This method leaves residual organic solvent in the prepared material, is complex, and limits the application areas of the prepared material. In addition, silica is also a common hard template material. However, when silica is also used as the main body of the core of the yolk-shell structure material, part of the core will be etched during the later etching process, resulting in a multi-layer cavity structure inside the material. The size of the cavity is difficult to control precisely, which limits the application of the material.

[0004] Therefore, developing a simple and feasible method to prepare yolk-shell structured nanoparticles with precisely controllable cavity size and stable internal core surface modification is of great research significance. Summary of the Invention

[0005] The purpose of this invention is to address the shortcomings of existing technologies by providing a method for preparing yolk-shell structured mesoporous nanomaterials. This method is economical, efficient, flexible, and simple to operate. The resulting yolk-shell structured mesoporous nanomaterials have a structure with adjustable core surface modification groups and precisely controllable cavity size. They can serve as nanocontainers to effectively fix guest metal nanoparticles within the cavity between the core and shell, and can also limit the size of the guest nanoparticles.

[0006] Technical solution

[0007] This invention uses surface-functionalized organosilicon spheres as a hard template. A silica layer and an organosilicon layer are sequentially grown on the surface through a layer-by-layer deposition method. During the subsequent hydrothermal treatment, the silica layer is dissolved and rearranged with the outer organosilicon layer, ultimately yielding a mesoporous material with an egg yolk-shell structure. The specific scheme is as follows:

[0008] A method for preparing a yolk-shell structured mesoporous nanomaterial includes the following steps:

[0009] (1) Dissolve hexadecyltrimethylammonium bromide (CTAB) in a mixed solvent of ethanol and water to obtain a hexadecyltrimethylammonium bromide solution. After adjusting the solution to weak alkalinity by adding concentrated ammonia dropwise, 1,2-bis(triethoxysilyl ethane) is added dropwise under stirring. After stirring for 2-4 hours, 3-aminopropyltrimethoxysilane is added dropwise and the stirring continues. After the reaction is completed, the solid product is separated, washed with alcohol and dried under vacuum to obtain amino-modified organosilicon nanospheres.

[0010] (2) After grinding the amino-modified organosilicon nanospheres, add them to a mixed solvent of ethanol and water, disperse them evenly by ultrasonication, then add hexadecyltrimethylammonium bromide (CTAB) and concentrated ammonia, stir evenly, add tetraethyl orthosilicate dropwise, stir the reaction for 1-3 hours, then add 1,2-bistriethoxysilyl ethane dropwise, continue stirring the reaction to obtain the reaction solution;

[0011] (3) The reaction solution was loaded into the reaction vessel and transferred to the oven for heating and standing. After the reaction was completed, it was taken out, separated and purified to obtain egg yolk-shell structured mesoporous nanomaterials.

[0012] Furthermore, in step (1), the volume ratio of ethanol to water in the mixed solvent of ethanol and water is 1:3.

[0013] Furthermore, in step (1), the volume ratio of 1,2-bis(triethoxysilyl ethane) to 3-aminopropyltrimethoxysilane is 10:1.

[0014] Furthermore, in step (1), the vacuum drying temperature is 60°C.

[0015] Furthermore, in step (2), the volume ratio of ethanol to water in the mixed solvent of ethanol and water is 2:5.

[0016] Furthermore, in step (2), the volume ratio of tetraethyl orthosilicate to 1,2-bis(triethoxysilyl ethane) is (5-15):30.

[0017] Furthermore, in step (3), the temperature of the heating and static setting is 100°C and the time is 10-14h.

[0018] Further, in step (3), the separation and purification method is as follows: after the reaction solution is separated into solid and liquid, the solid product is washed with ethanol, dried under vacuum, dispersed in a mixed solution of concentrated hydrochloric acid and ethanol with a volume ratio of 1:100, treated at 60°C for 6 hours, then separated into solid and liquid, and the solid product is dried under vacuum.

[0019] The beneficial effects of this invention are:

[0020] This invention discloses a method for preparing egg yolk-shell structured mesoporous nanomaterials. The method is simple, economical and efficient. The prepared egg yolk-shell structured mesoporous nanomaterials have a structure in which the core surface modification groups can be adjusted and the cavity size can be precisely controlled. They can be used as nanocontainers to encapsulate noble metal nanoparticles, effectively fixing guest metal nanoparticles in the cavity between the core and shell. Furthermore, the size of the nanoparticles can be precisely controlled by adjusting the size of the cavity. Attached Figure Description

[0021] Figure 1 These are TEM images of the egg yolk-shell structured mesoporous nanomaterials prepared in Example 1 at different magnifications.

[0022] Figure 2 This is a TEM image of the egg yolk-shell structured mesoporous nanomaterial prepared in Example 1 after loading gold nanoparticles.

[0023] Figure 3 These are TEM images of the egg yolk-shell structured mesoporous nanomaterials prepared in Example 2 at different magnifications.

[0024] Figure 4 This is a TEM image of the egg yolk-shell structured mesoporous nanomaterial prepared in Example 2 after loading gold nanoparticles.

[0025] Figure 5 These are TEM images of the egg yolk-shell structured mesoporous nanomaterials prepared in Example 3 at different magnifications.

[0026] Figure 6 This is a TEM image of the egg yolk-shell structured mesoporous nanomaterial prepared in Example 3 after loading gold nanoparticles. Detailed Implementation

[0027] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0028] Example 1

[0029] A method for preparing a yolk-shell structured mesoporous nanomaterial includes the following steps:

[0030] (1) Dissolve 0.12 g of hexadecyltrimethylammonium bromide in a mixed solvent consisting of 10 mL of ethanol and 30 mL of water to obtain a hexadecyltrimethylammonium bromide solution. After adjusting the solution to a weakly alkaline state by adding 1 mL of concentrated ammonia, add 0.5 mL of 1,2-bis(triethoxysilyl ethane) dropwise while stirring. After stirring for 3 h, add 0.05 mL of 3-aminopropyltrimethoxysilane dropwise and continue stirring for 12 h. After the reaction is complete, separate the solid product, wash with alcohol, and dry under vacuum at 60 °C overnight to obtain amino-modified organosilicon nanospheres.

[0031] (2) After grinding the amino-modified organosilicon nanospheres, 0.5 g was added to a mixed solvent consisting of 30 mL ethanol and 75 mL water. The mixture was ultrasonically dispersed evenly. Then, 0.18 g of hexadecyltrimethylammonium bromide and 1 mL of concentrated ammonia were added. After stirring evenly at 30 °C, 0.05 mL of tetraethyl orthosilicate was added dropwise. The mixture was stirred for 2 h. Then, 0.3 mL of 1,2-bis(triethoxysilyl ethane) was added dropwise. The mixture was stirred for another 2 h to obtain the reaction solution.

[0032] (3) The reaction solution was loaded into the reaction vessel and transferred to the oven for heating and standing (100℃, 12h). After the reaction was completed, the solid product was removed by centrifugation and washed three times with ethanol. After vacuum drying at 60℃ overnight, it was dispersed in a mixed solution of concentrated hydrochloric acid and ethanol with a volume ratio of 1:100 and treated at 60℃ for 6h. Then the solid and liquid were separated, and the solid product was vacuum dried to obtain the egg yolk-shell structured mesoporous nanomaterial.

[0033] Figure 1 These are TEM images of the egg yolk-shell structured mesoporous nanomaterials prepared in Example 1 at different magnifications. Figure 1 The scale bar in a is 400 nm. Figure 1 The scale bar in b is 100 nm. Figure 1 The scale bar in c is 50nm, from Figure 1As can be seen, the outermost layer of the nanomaterial is a light-colored shell with a thickness of about 13nm, and the inside is a core with a color that gradually darkens from the outside to the inside. There is a cavity with a thickness of about 1.1nm between the core and the shell.

[0034] Using the yolk-shell structured mesoporous nanomaterial prepared in Example 1 as a nanocontainer, gold nanoparticles were immobilized into the cavity of the yolk-shell structured mesoporous nanomaterial by in-situ reduction. The detailed method was as follows: 2 mg of HAuCl4·4H2O was dispersed in 10 mL of ethanol aqueous solution (ethanol to water volume ratio of 19:1), and 100 mg of...

[0035] The egg yolk-shell structured mesoporous nanomaterials prepared in Example 1 were ultrasonically dispersed and thoroughly stirred. Then, the ethanol was removed by rotary evaporation, and the mixture was heated to 200°C in a hydrogen-argon mixed atmosphere (10% hydrogen) and kept at that temperature for 2 hours to obtain egg yolk-shell structured mesoporous nanomaterials loaded with gold nanoparticles.

[0036] Figure 2 This is a TEM image of the egg yolk-shell structured mesoporous nanomaterial prepared in Example 1 after loading gold nanoparticles. Figure 2 The scale bar for 'a' is 50 nm. Figure 2 The scale bar for b is 20 nm, which shows that the size of the gold nanoparticles is around 1 nm.

[0037] Example 2

[0038] A method for preparing a yolk-shell structured mesoporous nanomaterial includes the following steps:

[0039] (1) Dissolve 0.12 g of hexadecyltrimethylammonium bromide in a mixed solvent consisting of 10 mL of ethanol and 30 mL of water to obtain a hexadecyltrimethylammonium bromide solution. After adjusting the solution to a weakly alkaline state by adding 1 mL of concentrated ammonia, add 0.5 mL of 1,2-bis(triethoxysilyl ethane) dropwise while stirring. After stirring for 3 h, add 0.05 mL of 3-aminopropyltrimethoxysilane dropwise and continue stirring for 12 h. After the reaction is complete, separate the solid product, wash with alcohol, and dry under vacuum at 60 °C overnight to obtain amino-modified organosilicon nanospheres.

[0040] (2) After grinding the amino-modified organosilicon nanospheres, 0.5 g was added to a mixed solvent consisting of 30 mL ethanol and 75 mL water. The mixture was ultrasonically dispersed evenly. Then, 0.18 g of hexadecyltrimethylammonium bromide and 1 mL of concentrated ammonia were added. After stirring evenly at 30 °C, 0.1 mL of tetraethyl orthosilicate was added dropwise. The mixture was stirred for 2 h. Then, 0.3 mL of 1,2-bis(triethoxysilyl ethane) was added dropwise. The mixture was stirred for another 2 h to obtain the reaction solution.

[0041] (3) The reaction solution was loaded into the reaction vessel and transferred to the oven for heating and standing (100℃, 12h). After the reaction was completed, the solid product was removed by centrifugation and washed three times with ethanol. After vacuum drying at 60℃ overnight, it was dispersed in a mixed solution of concentrated hydrochloric acid and ethanol with a volume ratio of 1:100 and treated at 60℃ for 6h. Then the solid and liquid were separated, and the solid product was vacuum dried to obtain the egg yolk-shell structured mesoporous nanomaterial.

[0042] Figure 3 These are TEM images of the egg yolk-shell structured mesoporous nanomaterials prepared in Example 2 at different magnifications. Figure 3 The scale bar in a is 400 nm. Figure 3 The scale bar in b is 100 nm. Figure 3 The scale bar in c is 50nm, from Figure 3 It can be seen that the nanomaterial has a distinct core-shell structure, with a cavity size of 2.3 nm between the core and shell.

[0043] Gold nanoparticles were immobilized in the cavities of the material using an in-situ reduction method. A TEM image of the egg yolk-shell structure mesoporous nanomaterial loaded with gold nanoparticles obtained in Example 2 is shown below. Figure 4 ,in Figure 4 The scale bar for 'a' is 50 nm. Figure 4 The scale bar for b is 20 nm, which shows that the size of the gold nanoparticles is around 2 nm.

[0044] Example 3

[0045] A method for preparing a yolk-shell structured mesoporous nanomaterial includes the following steps:

[0046] (1) Dissolve 0.12 g of hexadecyltrimethylammonium bromide in a mixed solvent consisting of 10 mL of ethanol and 30 mL of water to obtain a hexadecyltrimethylammonium bromide solution. After adjusting the solution to a weakly alkaline state by adding 1 mL of concentrated ammonia, add 0.5 mL of 1,2-bis(triethoxysilyl ethane) dropwise while stirring. After stirring for 3 h, add 0.05 mL of 3-aminopropyltrimethoxysilane dropwise and continue stirring for 12 h. After the reaction is complete, separate the solid product, wash with alcohol, and dry under vacuum at 60 °C overnight to obtain amino-modified organosilicon nanospheres.

[0047] (2) After grinding the amino-modified organosilicon nanospheres, 0.5 g was added to a mixed solvent consisting of 30 mL ethanol and 75 mL water. The mixture was ultrasonically dispersed evenly. Then, 0.18 g of hexadecyltrimethylammonium bromide and 1 mL of concentrated ammonia were added. After stirring evenly at 30 °C, 0.15 mL of tetraethyl orthosilicate was added dropwise. The mixture was stirred for 2 h. Then, 0.3 mL of 1,2-bistriethoxysilyl ethane was added dropwise. The mixture was stirred for another 2 h to obtain the reaction solution.

[0048] (3) The reaction solution was loaded into the reaction vessel and transferred to the oven for heating and standing (100℃, 12h). After the reaction was completed, the solid product was removed by centrifugation and washed three times with ethanol. After vacuum drying at 60℃ overnight, it was dispersed in a mixed solution of concentrated hydrochloric acid and ethanol with a volume ratio of 1:100 and treated at 60℃ for 6h. Then the solid and liquid were separated, and the solid product was vacuum dried to obtain the egg yolk-shell structured mesoporous nanomaterial.

[0049] Figure 5 These are TEM images of the egg yolk-shell structured mesoporous nanomaterials prepared in Example 3 at different magnifications. Figure 5 The scale bar in a is 400 nm. Figure 5 The scale bar in b is 100 nm. Figure 5 The scale bar in c is 50nm, from Figure 3 It can be seen that the nanomaterial has a distinct core-shell structure, with a cavity size of 6.0 nm between the core and shell.

[0050] Gold nanoparticles were immobilized in the cavities of the material using an in-situ reduction method. A TEM image of the egg yolk-shell structure mesoporous nanomaterial loaded with gold nanoparticles obtained in Example 3 is shown below. Figure 6 ,in Figure 6 The scale bar for 'a' is 50 nm. Figure 6 The scale bar for b is 20 nm, which shows that the size of the gold nanoparticles is around 6 nm.

Claims

1. A method for preparing a yolk-shell structured mesoporous nanomaterial, characterized in that, The steps include: (1) Dissolving hexadecyltrimethylammonium bromide in a mixed solvent of ethanol and water to obtain a hexadecyltrimethylammonium bromide solution, adding concentrated ammonia to adjust the solution to weak alkalinity, then adding 1,2-bis(triethoxysilyl ethane) under stirring, stirring for 2-4 hours, then adding 3-aminopropyltrimethoxysilane, continuing to stir, and after the reaction is completed, separating the solid product, washing with alcohol and drying under vacuum to obtain amino-modified organosilicon nanospheres; (2) Grinding the amino-modified organosilicon nanospheres and adding them to a mixed solvent of ethanol and water, dispersing them evenly by ultrasonication, then adding hexadecyltrimethylammonium bromide and concentrated ammonia, stirring evenly, then adding tetraethyl orthosilicate, stirring for 1-3 hours, then adding 1,2-bis(triethoxysilyl ethane), continuing to stir, and obtaining a reaction solution; (3) Placing the reaction solution into a reaction vessel and transferring it to an oven for heating and standing, then removing it after the reaction is completed, separating and purifying it to obtain egg yolk-shell structure mesoporous nanomaterials; In step (2), the volume ratio of tetraethyl orthosilicate to 1,2-bis(triethoxysilyl ethane) is (5-15):30; In step (3), the separation and purification method is as follows: after the reaction solution is separated into solid and liquid, the solid product is washed with ethanol, dried under vacuum, dispersed in a mixed solution of concentrated hydrochloric acid and ethanol with a volume ratio of 1:100, treated at 60°C for 3-6 hours, then separated into solid and liquid, and the solid product is dried under vacuum.

2. The method for preparing the yolk-shell structured mesoporous nanomaterial as described in claim 1, characterized in that, In step (1), the volume ratio of ethanol to water in the mixed solvent of ethanol and water is 1:

3.

3. The method for preparing the yolk-shell structured mesoporous nanomaterial as described in claim 1, characterized in that, In step (1), the volume ratio of 1,2-bis(triethoxysilyl ethane) to 3-aminopropyltrimethoxysilane is 10:

1.

4. The method for preparing the yolk-shell structured mesoporous nanomaterial as described in claim 1, characterized in that, In step (1), the vacuum drying temperature is 60°C.

5. The method for preparing the yolk-shell structured mesoporous nanomaterial as described in claim 1, characterized in that, In step (2), the volume ratio of ethanol to water in the mixed solvent of ethanol and water is 2:

5.

6. The method for preparing the yolk-shell structured mesoporous nanomaterial as described in claim 1, characterized in that, In step (3), the heating and static setting temperature is 100℃ and the time is 10-14h.

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