Multilayer layered meso-porous silicon nanotube as well as preparation method and application thereof

Abstract

The invention relates to a multilayer layered mesoporous silicon nanotube and a preparation method and application thereof, and the preparation method comprises the following steps: mixing a single-chain surfactant, a double-chain surfactant and water to obtain a mixed solution; mixing the obtained mixed solution with alkali and a silane precursor for reaction; and washing a reaction product obtained by the reaction, and roasting at high temperature to obtain the multilayer layered mesoporous silicon nanotube. Compared with the prior art, the prepared mesoporous silicon nanotube has a long-range ordered layered mesoporous structure, the outer tube diameter is 20-60 nm, the interlayer spacing is 2.0-20 nm, the specific surface area is 100-1200 m < 2 > / g, the mesoporous silicon nanotube is expected to be applied to the field of heat insulation, and the preparation method is high in controllability and suitable for preparation of layered mesoporous silicon of a series of sizes.

Description

Technical Field

[0001] The present invention relates to the technical field of functional material preparation, and in particular to a multi-layered mesoporous silicon nanotube and a preparation method and application thereof. Background Art

[0002] Layered structures are widely found in nature, such as bamboo and the bark of trees. At the microscopic scale, nanomaterials with well-defined layered, ordered structures have also attracted widespread attention. Multilayered structures are of great significance for enhancing the mechanical and thermal insulation properties of materials, which is closely related to the long-range arrangement of the layered structures. Like bamboo, multilayered structures can increase the support force of the material, thereby achieving higher mechanical strength and preventing instability. At the same time, the arrangement of multiple enclosed air layers can maintain a large amount of gas inside the material, limiting gas heat convection and reducing liquid infiltration, thereby reducing the thermal conductivity.

[0003] Given these advantages, significant research has been conducted in recent years on the synthesis of multilayered mesoporous materials. However, most reports to date have relied on preassembled amphiphilic block copolymers, using self-assembled block copolymers as hard templates for the mesoporous materials. However, the synthesis of block copolymers is complex, and defects often occur during the self-assembly process, making it difficult to achieve long-range ordered phase separation structures and long-range order, limiting the materials' further practical applications. Summary of the Invention

[0004] The purpose of the present invention is to provide a multi-layered mesoporous silicon nanotube and its preparation method and application, which has a long-range ordered multi-layered structure.

[0005] The purpose of the present invention can be achieved by the following technical solutions:

[0006] One of the technical solutions of the present invention provides a method for preparing multilayer mesoporous silicon nanotubes, comprising mixing a single-chain surfactant, a double-chain surfactant and water to obtain a mixed liquid; mixing the obtained mixed liquid with an alkali and a silane precursor to react; washing the reaction product obtained by the reaction and calcining it at high temperature to obtain the multilayer mesoporous silicon nanotubes.

[0007] Specifically, the preparation method of the present invention comprises the following steps:

[0008] (1) mixing a single-chain surfactant, a double-chain surfactant, a pore-enlarging agent, and water to obtain a mixed solution;

[0009] (2) mixing the mixed solution obtained in step (1) with a base and a silane precursor to react;

[0010] (3) The reaction product is washed and calcined at high temperature to remove the surfactant, thereby obtaining the multilayered mesoporous silicon nanotubes.

[0011] Preferably, the single-chain surfactant is one or more cationic surfactants; and the double-chain surfactant is one or more cationic surfactants.

[0012] In the present invention, the surfactant is a structure-directing agent used to construct layered mesopores, and all of them are cationic surfactants.

[0013] More preferably, the cationic surfactant is a quaternary ammonium salt surfactant containing an organic alkyl chain.

[0014] More preferably, the single-chain surfactant is one or more quaternary ammonium surfactants containing a single organic alkyl chain; the double-chain surfactant is one or more quaternary ammonium surfactants containing two organic alkyl chains.

[0015] Preferably, the single-chain surfactant is one or more of cetyltrimethylammonium bromide, cetyltrimethylammonium chloride, octadecyltrimethylammonium bromide, octadecyltrimethylammonium chloride, eicosyltrimethylammonium bromide or eicosyltrimethylammonium chloride.

[0016] Preferably, the double-chain surfactant is one or more of didodecyldimethylammonium bromide, didodecyldimethylammonium chloride, ditetradecyldimethylammonium bromide, ditetradecyldimethylammonium chloride, dihexadecyldimethylammonium bromide, dihexadecyldimethylammonium chloride, dioctadecyldimethylammonium chloride or dioctadecyldimethylammonium bromide.

[0017] Preferably, the silane precursor is one or more of organic silane or inorganic silane.

[0018] Further preferably, the silane precursor is one or more of tetramethyl silicate, tetraethyl silicate, tetrapropyl silicate, tetrabutyl silicate, tetraisopropyl silicate, tetra-tert-butyl silicate, 3-(2,3-epoxypropoxy)propyltrimethoxysilane, methyltriethoxysilane, 1,4-bis(triethoxysilyl)benzene or 1,2-bis(triethoxysilyl)ethane.

[0019] More preferably, the silane precursor is tetraethyl orthosilicate.

[0020] Preferably, the base is one or more of an organic base or an inorganic base.

[0021] In the present invention, the role of the base is to regulate the hydrolysis and cross-linking rate of the silane precursor to ensure its coordinated assembly with the surfactant. The base can be one or more of an organic base or an inorganic base.

[0022] More preferably, the base is one or more of sodium hydroxide, potassium hydroxide, calcium hydroxide, barium hydroxide, ammonia water, methylamine, ethylamine, dimethylamine, diethylamine, triethylamine or triethanolamine.

[0023] More preferably, the base is aqueous ammonia.

[0024] Preferably, the pore-enlarging agent is one or more hydrophobic pore-enlarging agents.

[0025] More preferably, the pore-enlarging agent is one or more of mesitylene, unsymmetrical trimethylol, trimethylol, cyclohexane, polymethyl methacrylate, polystyrene or poly-tert-butyl methacrylate.

[0026] Preferably, the molar ratio of the single-chain surfactant, double-chain surfactant, pore expander, base catalyst, silane precursor and water is in the range of (0.004-0.4): (0.0008-0.08): (0-80): (1-20): (0.4-20): 1000.

[0027] Preferably, the reaction temperature in step (2) is 30-70°C.

[0028] Preferably, the reaction time in step (2) is 0.05-48h.

[0029] Preferably, the high temperature calcination in step (3) is performed at a temperature of 500-1200° C. and a calcination time of 2-24 h.

[0030] Preferably, in step (3), the reaction product obtained by the reaction is washed, dried, and calcined at high temperature.

[0031] Further preferably, in step (3), anhydrous ethanol is used to wash the reaction product obtained by the reaction.

[0032] The second technical solution of the present invention provides a multilayered mesoporous silicon nanotube material, which is prepared by the above-mentioned preparation method, and is characterized in that the nanotube material has a long-range ordered layered mesoporous structure and a specific surface area of ​​100-1200m 2 / g, the outer diameter of the nanotubes is 20-60nm, and the interlayer spacing is 2.0-20nm.

[0033] The third technical solution of the present invention provides an application of the above-mentioned multilayered mesoporous silicon nanotubes in the field of thermal insulation. The multilayered mesoporous silicon nanotubes are used for thermal insulation. Specifically, the powder thermal conductivity of the multilayered mesoporous silicon material prepared by the present invention is 41.67mW·m -1 ·K -1 , which is at least 32.7% lower than that of other mesoporous materials.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] 1. The multilayered mesoporous silicon prepared by the present invention has a long-range ordered multilayered structure and a high specific surface area;

[0036] 2. The preparation method of the present invention is highly controllable, and the prepared multilayered mesoporous silicon nanotubes have the characteristics of adjustable interlayer spacing, tube diameter, and surface curvature, and are suitable for the preparation of layered mesoporous silicon of a range of sizes;

[0037] 3. The multilayered mesoporous silicon nanotubes prepared by the present invention have multiple long-range ordered layered pores and are expected to be applied in the field of thermal insulation. BRIEF DESCRIPTION OF THE DRAWINGS

[0038] Figure 1 This is a flow chart for preparing multilayered mesoporous silicon according to an embodiment of the present invention;

[0039] Figure 2 This is a scanning electron microscope image of the multilayered mesoporous silicon provided in Example 1 of the present invention;

[0040] Figure 3 This is a transmission electron microscope image of the multilayered mesoporous silicon provided in Example 1 of the present invention;

[0041] Figure 4 This is a high-magnification transmission electron microscope image of the multilayered mesoporous silicon provided in Example 1 of the present invention;

[0042] Figure 5 FIGURE 1 shows nitrogen adsorption and desorption of multilayered mesoporous silicon provided in Example 1 of the present invention;

[0043] Figure 6 This is a pore size distribution diagram of the multilayered mesoporous silicon provided in Example 1 of the present invention;

[0044] Figure 7 This is a small-angle X-ray scattering image of the multilayered mesoporous silicon provided in Example 1 of the present invention;

[0045] Figure 8 A comparison chart of the thermal insulation performance of the multilayered mesoporous silicon provided in Example 1 of the present invention;

[0046] Figure 9 This is a scanning electron microscope image of the multilayered mesoporous silicon provided in Example 2 of the present invention;

[0047] Figure 10 This is a transmission electron microscope image of the multilayered mesoporous silicon provided in Example 2 of the present invention;

[0048] Figure 11 Transmission electron microscope image of the sample provided for Comparative Example 1;

[0049] Figure 12 Transmission electron microscope image of the sample provided for Comparative Example 2;

[0050] Figure 13 Transmission electron microscope image of the sample provided for Comparative Example 3;

[0051] Figure 14 This is a transmission electron microscope image of the multilayered mesoporous silicon provided in Example 3 of the present invention;

[0052] Figure 15 This is a transmission electron microscope image of the multilayered mesoporous silicon provided in Example 4 of the present invention;

[0053] Figure 16 This is a transmission electron microscope image of the multilayered mesoporous silicon provided in Example 5 of the present invention. DETAILED DESCRIPTION

[0054] The present invention is described in detail below with reference to the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0055] Unless otherwise specified, the reagents, methods, instruments and equipment used in the present invention are conventional reagents, methods, instruments and equipment in the art. Unless otherwise specified, the reagents and materials used in the following examples are commercially available.

[0056] A multilayered mesoporous silicon nanotube and a preparation method thereof, such as Figure 1 As shown, the preparation method is specifically as follows: adding a surfactant and a pore-enlarging agent to water, stirring to obtain a mixed solution, in which layered micelles are formed; mixing an alkali and a silane precursor with the mixed solution, reacting and synergistically assembling; and finally high-temperature calcination to remove the surfactant to obtain the multilayered mesoporous silicon nanotubes. The obtained multilayered mesoporous silicon nanotubes have an outer diameter of 20-60nm, an interlayer spacing of 2.0-20nm, and a specific surface area of ​​100-1200m 2 / g.

[0057] The following describes the details in conjunction with specific embodiments.

[0058] Example 1

[0059] Mix 15 mg of hexadecyltrimethylammonium bromide (single-chain surfactant), 5 mg of dioctadecyldimethylammonium chloride (double-chain surfactant), 20 mL of water, 1 mL of mesitylene (pore expander) and 0.30 mL of ammonia water (25-28%), stir at 350 rpm at 50°C for 30 minutes to obtain a clear and transparent mixed solution, then add 1 mL of tetraethyl orthosilicate and continue stirring at 350 rpm for 2 hours; the resulting product is washed with anhydrous ethanol and then calcined at 700°C for 3 hours to remove the surfactant to obtain multilayered mesoporous silicon nanotubes.

[0060] In this embodiment, a single-chain surfactant hexadecyltrimethylammonium bromide (CTAB) and a double-chain surfactant dioctadecyldimethylammonium chloride (DODAC) are used as templates, tetraethyl orthosilicate (TEOS) is used as a silicon source, the template and the silicon source are synergistically assembled, and then the template is removed at high temperature to obtain the multilayered mesoporous silicon nanotubes.

[0061] For details, see Figure 2-4 , Figure 2 The scanning electron microscope image shows that the multilayered mesoporous silicon nanotubes obtained in Example 1 have a tubular morphology and are uniform in size. Figure 3-4 Transmission electron microscopy showed that the layered structure of mesoporous silicon nanotubes was clear and orderly, the surface was flat with no angle, the curvature was 0°, the outer tube diameter was about 32 nm, and the interlayer spacing was about 4.4 nm.

[0062] Figure 5 This is the nitrogen adsorption and desorption isotherm of the multilayered mesoporous silicon nanotubes obtained in Example 1. The adsorption curve is an IV curve, a typical adsorption isotherm of mesoporous materials. The obvious adsorption at a relative pressure of 0.5-0.8 corresponds to the mesopores. The specific surface area of ​​the material is 725m 2 / g

[0063] Figure 6 This is the pore size distribution curve of the multi-layered mesoporous silicon nanotubes obtained in Example 1. The curve shows that the material has a uniform pore size of 2.88 nm.

[0064] Figure 7 This is a small-angle X-ray scattering pattern of the multilayered mesoporous silicon nanotubes obtained in Example 1. Diffraction peaks at 100 and 200 can be observed in the diffraction pattern, corresponding to long-range ordered layered mesopores.

[0065] Figure 8 This is a comparison chart of the thermal insulation performance of the multilayered mesoporous silicon nanotubes obtained in Example 1. As shown in the figure, the thermal conductivity of the multilayered mesoporous silicon nanotube powder is 41.67mW·m -1 ·K -1 , which is at least 32.7% lower than that of other mesoporous materials.

[0066] Example 2

[0067] Mix 15 mg of hexadecyltrimethylammonium bromide (single-chain surfactant), 5 mg of dioctadecyldimethylammonium chloride (double-chain surfactant), 20 mL of water and 0.30 mL of ammonia water (25-28%), stir at 350 rpm at 50°C for 30 minutes to obtain a clear and transparent mixture, then add 1 mL of tetraethyl orthosilicate and continue stirring at 350 rpm for 2 hours; the resulting product is washed with anhydrous ethanol and then calcined at 700°C for 3 hours to remove the surfactant to obtain multilayered mesoporous silicon nanotubes.

[0068] See Figure 9-10 , Figure 9 Scanning electron microscopy images and Figure 10 Transmission electron microscopy images show that the multilayered mesoporous silicon has a regular bamboo-like nanotube morphology and a layered mesoporous structure. The tube diameter at the bamboo node connection is ~23.0nm, the angle is 138°, the tube diameter at the bamboo node is about ~32.0nm, and the interlayer spacing is about ~2.8nm.

[0069] Comparative Example 1

[0070] Compared with Example 1, most of the steps are the same, except that the introduction of the double-chain surfactant is omitted in this example.

[0071] like Figure 11 As shown, in the absence of the double-chain surfactant, the mesoporous structure is a two-dimensional hexagonal phase and cannot form a lamellar mesoporous structure.

[0072] Comparative Example 2

[0073] Compared with Example 1, most of the steps are the same, except that the introduction of the single-chain surfactant is omitted in this example.

[0074] like Figure 12 As shown, in the absence of single-chain surfactants, double-chain surfactants and silicon source precursors synergistically assembled to form hollow multilayer nanospheres.

[0075] Comparative Example 3

[0076] Compared with Example 1, most of the above are the same, except that in this example, the single-chain surfactant is adjusted to the double-chain surfactant dicetyldimethylammonium chloride.

[0077] like Figure 13 As shown, when the single-chain surfactant is replaced by other double-chain surfactants, multilayer mesoporous silica spheres can be obtained, but multilayer silica nanotubes cannot be formed.

[0078] Example 3

[0079] Compared with Example 1, most of the above are the same, except that the double-chain surfactant in this example is adjusted to didodecyldimethylammonium bromide.

[0080] See Figure 14 , Figure 14 Transmission electron microscopy images show that the multilayered mesoporous silicon has a distinct regular bamboo-like nanotube morphology and a layered mesoporous structure. The tube diameter at each bamboo node is ~30.3nm, the angle at the bamboo node connection is 112°, the tube diameter at the bamboo node is about ~48.5nm, and the interlayer spacing is about ~3.2nm.

[0081] Example 4

[0082] Compared with Example 1, most of the above are the same, except that the single-chain surfactant in this example is adjusted to eicosyltrimethylammonium bromide.

[0083] See Figure 15 , Figure 15 Transmission electron microscopy images show that the multilayered mesoporous silicon has a smooth surface, a tube diameter of ~25.3nm, a clear layered mesoporous structure, and an interlayer spacing of approximately ~4.1nm.

[0084] Example 5

[0085] Compared with Example 1, most of the above are the same, except that the amount of pore-enlarging agent added in this example is adjusted to 7 mL.

[0086] See Figure 16 , Figure 16 Transmission electron microscopy images show that the surface of the multilayered mesoporous silicon is relatively flat, with a layered mesoporous structure and an interlayer spacing of approximately 6.13 nm.

[0087] Example 6

[0088] Compared with Example 1, most of the contents are the same, except that the addition amounts of the single-chain surfactant and the double-chain surfactant in this example are adjusted to 75 mg and 25 mg.

[0089] Example 7

[0090] Compared with Example 1, most of the steps are the same except that the reaction temperature is adjusted to 65°C in this example.

[0091] Example 8

[0092] Compared with Example 1, most of the details are the same, except that the high-temperature calcination temperature is adjusted to 1200°C in this example.

[0093] The above description of the embodiments is intended to facilitate understanding and use of the 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 above-described embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of the present invention, without departing from the scope of the present invention, should be within the scope of protection of the present invention.

Claims

1. A method for preparing multilayered mesoporous silicon nanotubes, characterized in that: The following steps are involved: (1) mixing a single-chain surfactant, a double-chain surfactant, and water to obtain a mixed solution; (2) mixing the mixed solution obtained in step (1) with a base and a silane precursor to react; (3) washing the reaction product and calcining it at high temperature to obtain the multi-layered mesoporous silicon nanotubes.

2. The method for preparing multi-layered mesoporous silicon nanotubes according to claim 1, characterized in that: The single-chain surfactant is one or more cationic surfactants; the double-chain surfactant is one or more cationic surfactants.

3. The method for preparing multi-layered mesoporous silicon nanotubes according to claim 2, characterized in that: The cationic surfactant is a quaternary ammonium surfactant containing an organic alkyl chain; The single-chain surfactant is one or more quaternary ammonium surfactants containing a single organic alkyl chain; The double-chain surfactant is one or more quaternary ammonium salt surfactants containing double organic alkyl chains.

4. The method for preparing multi-layered mesoporous silicon nanotubes according to claim 1, characterized in that: The silane precursor is one or more of organic silane or inorganic silane; The base is one or more of an organic base or an inorganic base.

5. The method for preparing multi-layered mesoporous silicon nanotubes according to claim 4, characterized in that: The silane precursor is one or more of tetramethyl silicate, tetraethyl silicate, tetrapropyl silicate, tetrabutyl silicate, tetraisopropyl silicate, tetra-tert-butyl silicate, 3-(2,3-epoxypropoxy)propyltrimethoxysilane, methyltriethoxysilane, 1,4-bis(triethoxysilyl)benzene or 1,2-bis(triethoxysilyl)ethane; The base is one or more of sodium hydroxide, potassium hydroxide, calcium hydroxide, barium hydroxide, ammonia water, methylamine, ethylamine, dimethylamine, diethylamine, triethylamine or triethanolamine.

6. The method for preparing multi-layered mesoporous silicon nanotubes according to claim 1, characterized in that: The molar ratio of the single-chain surfactant, the double-chain surfactant, the base, the silane precursor and the water is in the range of (0.004-0.4): (0.0008-0.08): (1-20): (0.4-20): 1000.

7. The method for preparing multi-layered mesoporous silicon nanotubes according to claim 1, characterized in that: In the step (1), a single-chain surfactant, a double-chain surfactant, a pore-enlarging agent and water are mixed to obtain a mixed solution; The pore-enlarging agent is one or more hydrophobic pore-enlarging agents.

8. The method for preparing multi-layered mesoporous silicon nanotubes according to claim 1, characterized in that: The reaction temperature in step (2) is 30-70° C., and the reaction time is 0.05-48 h; The high-temperature calcination in step (3) is performed at a temperature of 500-1200° C. and for a time of 2-24 hours.

9. A multilayered mesoporous silicon nanotube, characterized in that: The preparation method according to any one of claims 1 to 8 is used to prepare the nanostructured ... 2 / g, the outer diameter of the nanotubes is 20-60nm, and the interlayer spacing is 2.0-20nm.

10. Use of the multi-layered mesoporous silicon nanotubes according to claim 9 in the field of thermal insulation.

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