Metal oxide hollow nanotube array material, preparation method and application thereof

Abstract

The present application relates to a kind of metal oxide hollow nanotube array material and its preparation method and application, belong to nanometer material technical field.The preparation method of the present application includes the following steps: S1, the substrate loaded with columnar micellar seed is soaked in solvent A, under oscillation condition, drop the solution of block copolymer, through stationary aging, elution and drying, obtain block copolymer nanobrush;S2, the block copolymer nanobrush of S1 is soaked in metal salt solution, after washing, again be soaked in solvent B by supercritical drying, obtain metal salt nanotube array material;S3, the metal salt nanotube array material of S2 is calcined, obtain the metal oxide hollow nanotube array material.The preparation method of the present application proposes the template guiding effect of block copolymer nanobrush, so that it can guide multifunctional metal oxide nanotube array, and on this basis, the adjustment of nanotube of different height is realized.

Description

Technical Field

[0001] This invention belongs to the field of nanomaterials technology, and particularly relates to a metal oxide hollow nanotube array material, its preparation method and application. Background Technology

[0002] Metal oxides, due to their unique electrical, magnetic, and thermal properties, have been widely used in catalysis, sensing, and energy storage. To effectively improve the performance of metal oxides, the rational design of highly oriented and compositionally tunable metal oxides has become a continuous pursuit. In recent years, researchers have successfully induced various forms of metal oxides using commercially available soft templates, such as porous metal oxide bulks, metal oxide nanowires, and metal oxide nanotubes. However, the metal oxides prepared by this strategy suffer from low porosity, disordered structure, and small surface area. This deficiency is mainly attributed to the low molecular weight and low decomposition temperature of commercially available soft templates, which leads to excessively rapid decomposition at low temperatures, failing to support the oxide crystallization process. Therefore, developing reasonable induction strategies has become a top priority in current research.

[0003] Currently, people are trying to select SPs with low oxygen levels and high stability. 2 Hybridized carbon-containing block polymers were used as inducing templates to prepare highly ordered porous metal oxides. Although the aforementioned challenges were successfully overcome, this strategy is mainly limited to the solution state, which leads to lower controllability. Therefore, it is essential to realize the customization of highly oriented metal oxide nanoarrays at the interface.

[0004] Based on the above reasons, this application is hereby submitted. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a metal oxide hollow nanotube array material, its preparation method, and its applications. The block copolymer nanobrush used in this invention serves as a template, capable of spreading in a benign solvent and binding with a large amount of metal salts in the solvent, thereby coating the surface of the block copolymer nanobrush with metal salt particles. Because the pyridine functional groups in the block copolymer nanobrush structure can bind various metal ions, it can induce the formation of metal oxide nanotubes doped with various metal heteroatoms. In other words, it uses the block copolymer nanobrush with its crystallization-active growth characteristics as a template to directionally induce arrays of various metal oxide nanotubes. This method offers simple and flexible preparation conditions, and allows for precise control over the composition and thickness of the metal oxide nanotubes.

[0006] The first objective of this invention is to provide a method for preparing a metal oxide hollow nanotube array material, comprising the following steps:

[0007] S1. The substrate loaded with columnar micelle seeds is immersed in solvent A, and a block copolymer solution is added dropwise under oscillation. After static aging, rinsing and drying, a block copolymer nanobrush is obtained.

[0008] S2. The block copolymer nanobrush described in S1 is immersed in a metal salt solution, washed, and then immersed again in solvent B and dried by supercritical drying to obtain a metal salt nanotube array material.

[0009] S3. The metal salt nanotube array material described in S2 is calcined to obtain the metal oxide hollow nanotube array material.

[0010] In one embodiment of the present invention, in S1, the method for preparing the columnar micelle seed crystals includes the following steps: dissolving the block copolymer in solvent C and aging it at room temperature to obtain long columnar micelles; placing the long columnar micelles in an ice-water bath, ultrasonically treating them to break them, and aging them at room temperature to obtain columnar micelle seed crystals with a length of 50nm-60nm.

[0011] Furthermore, the ultrasonic treatment time is 0.25h-2h, and the intensity is 50W-140W.

[0012] Furthermore, the aging period is 1-2 days.

[0013] In one embodiment of the present invention, in S1, the method for preparing the substrate loaded with columnar micelle seeds includes the following steps: drop-coating a columnar micelle seed solution onto the substrate, followed by aging, rinsing, and drying to obtain the substrate loaded with columnar micelle seeds.

[0014] Furthermore, the substrate is a pretreated substrate, which involves ultrasonically cleaning the substrate in acetone and water for a total of 20-30 minutes and drying it under a nitrogen atmosphere.

[0015] Furthermore, the aging process involves aging at room temperature for 1-2 days.

[0016] Furthermore, the rinsing is performed using isobutanol. Rinsing removes free copolymers and seed crystals that are not fully bonded to the substrate.

[0017] Furthermore, the drying is carried out under a nitrogen atmosphere.

[0018] In one embodiment of the present invention, in S1, the substrate is selected from silicon dioxide, metal, glass, ceramic tube, nickel foam, plastic or carbon nanotube.

[0019] In one embodiment of the present invention, in S1, the concentration of the block copolymer solution is 1 mg / mL-20 mg / mL; the block copolymer is selected from PFS.24 -b-P2VP 314 PFS 27 -b-P2VP 356 and PFS 44 -b-P2VP 526 One or more of the following. The subscript for block copolymers refers to the degree of polymerization of each block.

[0020] Furthermore, the solvent of the block copolymer solution is tetrahydrofuran.

[0021] In one embodiment of the invention, in S1, the oscillation is oscillating on an oscillator for 10s-2h.

[0022] In one embodiment of the present invention, in S1, the static aging is performed by standing at room temperature for 0.5h-48h.

[0023] In one embodiment of the present invention, in S1, the rinsing is performed using isobutanol.

[0024] In one embodiment of the invention, in S1, the drying is carried out under a nitrogen atmosphere.

[0025] In one embodiment of the present invention, in S1, growth is initiated after the introduction of the block copolymer, using active crystallization-driven growth. The ends of the block copolymer nanobrush still possess active crystallization growth capability, enabling precise adjustment of the length of the block copolymer nanobrush and design of the shell structure according to functionalization requirements. Here, the length of the block copolymer nanobrush is mainly controlled by the amount of monomer added, while the diameter of the block copolymer nanobrush can be controlled by adjusting the block ratio, which is a key factor.

[0026] In one embodiment of the present invention, in S2, the concentration of the metal salt solution is 1 mmol / L-2 mmol / L; the metal salt is selected from ammonium metatungstate, silicotungstic acid, tetraethyl silicate, or ethoxytantalum.

[0027] Furthermore, the solvent for the metal salt solution is selected from one or more of water, ethanol, methanol, and isopropanol.

[0028] In one embodiment of the present invention, in S2, the soaking time in the metal salt solution is 3h-5h; the diameter of the metal oxide hollow nanotube array material can be controlled by adjusting the soaking time.

[0029] In one embodiment of the present invention, in S2, the washing is performed using an ethanol solution and / or an isopropanol solution to remove excess metal salts adhering to the surface of the block copolymer nanobrush.

[0030] In one embodiment of the present invention, in S2, the supercritical drying time is 2.5h-4h.

[0031] In one embodiment of the present invention, in S3, the calcination temperature is 450℃-550℃ and the time is 2h-4h.

[0032] In one embodiment of the present invention, solvent A and solvent C are independently selected from one or more of water, methanol, ethanol, propanol and isopropanol; solvent B is selected from one or more of isopropanol, tert-butanol and ethanol.

[0033] In one embodiment of the present invention, the method for preparing the metal oxide hollow nanotube array material further includes: introducing metal heteroatoms into a metal salt solution via pre-doping to obtain a doped metal oxide hollow nanotube array material. Utilizing the flexible coordination mode of the pyridine functional groups in the block copolymer nanobrush shell, metal heteroatoms can be easily introduced into the metal oxide nanotubes. Compared with conventional methods for preparing metal oxide nanotubes, this strategy is more flexible and effective. Furthermore, compared with pure metal oxide nanotubes, the introduced metal heteroatoms can modify the metal oxide, thereby further improving the performance of the metal oxide nanotubes.

[0034] Furthermore, the predoping method specifically involves immersing the block copolymer nanobrush described in S1 in a solution containing metal heteroatoms and multimetal-oxygen clusters, washing it, immersing it again in solvent B, supercritical drying, and calcining it to obtain the metal oxide hollow nanotube array material.

[0035] Preferably, the metal heteroatom is selected from copper atoms and / or silicon atoms.

[0036] Preferably, the polymetallic oxygen cluster is selected from ammonium metatungstate, silicotungstic acid, or ammonium polymolybdate.

[0037] Preferably, the solubility of polyoxometalates in the solution containing metal heteroatoms and polyoxometalates is 1 mmol / L to 2 mmol / L.

[0038] Preferably, the soaking time in a solution containing metal heteroatoms and polymetallic oxygen clusters is 3-5 hours.

[0039] A second objective of this invention is to provide a metal oxide hollow nanotube array material prepared by the method described above.

[0040] A third objective of this invention is to provide an application of the aforementioned metal oxide hollow nanotube array material in gas sensing.

[0041] In one embodiment of the present invention, the metal oxide hollow nanotube array material is used as a sensor. After aging at 250°C, it is connected to a gas-sensitive device. The response capability of the metal oxide hollow nanotube array material to gases such as methanol, ethanol, nitrogen dioxide, hydrogen sulfide, acetone, nitric oxide, toluene, and methane is determined by observing the change in resistance value.

[0042] The technical solution of the present invention has the following advantages compared with the prior art:

[0043] (1) The preparation method described in this invention proposes the template guiding effect of block copolymer nanobrushes, enabling them to guide multifunctional metal oxide nanotube arrays and, on this basis, achieve the adjustment of nanotubes of different heights. In addition, by utilizing the structural advantages of block copolymer nanobrushes, other functional heteroatoms are introduced during the preparation of metal oxide nanotube arrays. This is a step that is difficult to achieve in traditional metal oxide nanotube preparation. Therefore, the functional metal oxide hollow nanotube array material obtained can realize a variety of applications.

[0044] (2) The preparation method described in this invention is crucial for preparing various metal oxide hollow nanotube array materials. Furthermore, doping these materials with functional heteroatoms is a significant innovation of this strategy, as it is difficult to simultaneously introduce other heteroatoms in traditional methods for preparing metal oxide hollow nanotube array materials. The doped metal heteroatoms enhance H2S gas sensing. Undoped metal oxide hollow nanotube array materials also exhibit H2S gas sensing activity, but their selectivity is not as outstanding. Therefore, introducing metal heteroatoms with redox properties further improves their selectivity. Attached Figure Description

[0045] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein:

[0046] Figure 1 This is a schematic diagram of the preparation of metal oxide hollow nanotube array material in Example 1 of the present invention;

[0047] Figure 2 This is a SEM image of the WO3 hollow nanotube array material prepared in Example 1 of this invention;

[0048] Figure 3 The image shows the XRD pattern of the WO3 hollow nanotube array material prepared in Example 1 of this invention.

[0049] Figure 4 This is a cross-sectional SEM image of the WO3 hollow nanotube array material prepared in Example 2 of this invention.

[0050] Figure 5 The image shows the gas sensing response of the copper-doped WO3 hollow nanotube array material in Application Example 1 of this invention.

[0051] Figure 6 The diagram shows the cyclic stability of WO3 hollow nanotube array materials with different doping amounts in Application Example 2 of this invention. Detailed Implementation

[0052] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0053] Example 1

[0054] The metal oxide hollow nanotube array material and its preparation method of the present invention specifically include the following steps:

[0055] S1. Preparation of block copolymer nanobrushes

[0056] S11. Preparation of columnar micelle seed solution: Add block copolymer PFS to isopropanol 44 -b-P2VP 526 The block copolymer solution was stirred at 80℃ for 30 min to completely dissolve it, resulting in a concentration of 0.5 mg / mL. Then, it was allowed to stand at room temperature for 1 day to obtain long columnar micelles. The long columnar micelles were placed in an ice-water bath at 0℃ and sonicated for 0.5 h using a probe ultrasonic processor (80W) to break them. After standing for 1 day, a columnar micelle seed solution with a length of about 58 nm was obtained.

[0057] S12. Preparation of silicon wafers loaded with columnar micelle seeds: The silicon wafer (1cm×1cm) was ultrasonically cleaned in acetone and water for 30min, dried in a nitrogen atmosphere, and then subjected to oxygen-plasma treatment for 10min; then 20μL of columnar micelle seed solution was drop-coated onto the silicon wafer, aged at room temperature for 1 day, rinsed with isobutanol and dried in a nitrogen atmosphere to obtain silicon wafers with columnar micelle seeds loaded on the surface;

[0058] S13. Preparation of silicon wafers loaded with block copolymer nanobrushes: Place the silicon wafer loaded with micellar seeds in 1 mL of isopropanol, and add 8 μL of block copolymer PFS with a concentration of 10 mg / mL. 24 -b-P2VP 314 The solution (solvent is tetrahydrofuran) was shaken on a shaker for 30 min and then allowed to stand at room temperature for 0.5 h. Finally, it was rinsed with isobutanol and dried under nitrogen to obtain a silicon wafer loaded with block copolymer nanobrushes.

[0059] S2, Preparation of metal salt nanotube array materials ( Figure 1 )

[0060] A silicon wafer loaded with block copolymer nanobrushes was placed in a 1 mmol / L ammonium metatungstate solution (solvents were isopropanol and water) for 3 h, then rinsed with an ethanol solution, and subsequently supercritically dried in an ethanol solution for 3 h to obtain a metal salt nanotube array material with an upright morphology.

[0061] S3. Preparation of metal oxide hollow nanotube array materials ( Figure 1 )

[0062] Metal salt nanotube array materials were placed in a nitrogen atmosphere and calcined at 500°C for 3 hours to obtain WO3 hollow nanotube array materials.

[0063] The array of WO3 hollow nanotubes grown on a silicon wafer was characterized using scanning electron microscopy (SEM), such as... Figure 2 As shown. From Figure 2 As can be seen, dense nanorods are grown on the silicon wafer, and each nanorod is uniformly coated with a layer of oxide. These nanorods are uniformly arranged to form an array.

[0064] X-ray diffraction (XRD) was used to characterize the array of WO3 hollow nanotubes grown on a silicon wafer, such as... Figure 3 As shown. From Figure 3 It can be seen that WO3 hollow nanotubes belong to the γ phase.

[0065] Example 2

[0066] The metal oxide hollow nanotube array material and its preparation method of the present invention specifically include the following steps:

[0067] S1. Preparation of block copolymer nanobrushes:

[0068] S11. Preparation of columnar micelle seed solution: Same as in Example 1;

[0069] S12. Preparation of ceramic tubes loaded with columnar micelle seeds: The ceramic tubes were ultrasonically cleaned in acetone and water for a total of 30 min and dried in a nitrogen atmosphere. Then the ceramic tubes were repeatedly immersed in the columnar micelle seed solution three times, aged at room temperature for 1 day, rinsed with isobutanol and dried in a nitrogen atmosphere to obtain ceramic tubes with columnar micelle seeds loaded on the surface.

[0070] S13. Preparation of ceramic tubes loaded with block copolymer nanobrushes: Place the ceramic tube loaded with micelle seeds in 1 mL of isopropanol, and add 8 μL of block copolymer PFS with a concentration of 10 mg / mL. 24 -b-P2VP 314The solution (solvent is tetrahydrofuran) was shaken on a shaker for 30 min and then allowed to stand at room temperature for 0.5 h. Finally, it was rinsed with isobutanol and dried under nitrogen to obtain a ceramic tube loaded with block copolymer nanobrushes.

[0071] S2. Preparation of metal salt nanotube array materials

[0072] Ceramic tubes loaded with block copolymer nanobrushes were placed in a 1 mmol / L ammonium metatungstate solution (solvents were isopropanol and water) for 3 h, then rinsed with an ethanol solution, and subsequently supercritically dried in an ethanol solution for 3 h to obtain a metal salt nanotube array material with an upright morphology.

[0073] S3. Preparation of metal oxide hollow nanotube array materials

[0074] Metal salt nanotube array materials were placed in a nitrogen atmosphere and calcined at 500°C for 3 hours to obtain WO3 hollow nanotube array materials.

[0075] The array of WO3 hollow nanotubes grown on ceramic tubes was characterized using scanning electron microscopy (SEM), such as... Figure 4 As shown. From Figure 4 As can be seen, the ceramic tube is composed of blocks of metal oxides, on which many regularly arranged nanorods are grown. Each nanorod is uniformly coated with a layer of oxide, and these nanotubes are uniformly arranged to form an array. In addition, when the block copolymer nanobrush is combined with the metal oxide particles, the rigidity of the metal oxide particles allows the nanobrush coated with metal oxide particles to stand upright in a dry state.

[0076] Example 3

[0077] The copper-doped WO3 hollow nanotube array material and its preparation method of the present invention specifically include the following steps:

[0078] The process is basically the same as in Example 1, except that in S2: the silicon wafer loaded with block copolymer nanobrushes is placed in a 1 mmol / L ammonium metatungstate solution (solvents are isopropanol and water), followed by the addition of a 2 mmol / L copper acetate solution (solvent is ethanol). The above process is performed by shaking on an oscillator for 3 hours, then the wafer is rinsed with an ethanol solution, and then supercritically dried in an ethanol solution for 3 hours to obtain a metal salt nanotube array material with an upright morphology.

[0079] Application Example 1

[0080] The WO3 hollow nanotube array material doped with copper atoms grown on the silicon wafer surface in Example 3 was used as a sensor for gas sensing.

[0081] The gas sensitivity of a copper-doped WO3 hollow nanotube array was detected using an MA1.0 gas-sensitive testing device. A ceramic tube with Au electrodes was used as the sensing substrate. A Ni-Cr alloy wire was used as the heater. An adjustable operating temperature was provided to the sensing material by applying a specific voltage. The assembled sensing device was mounted on a PCB support, and a pair of electrodes were connected to the material. The material was then aged at 250°C for two days to remove excess solvent molecules from the WO3 structure. The target analyte was then passed through the gas sensor. The sensitivity of the copper-doped WO3 hollow nanotube array to different gases was determined by observing changes in resistance. The results are as follows: Figure 5 As shown. From Figure 5 It can be seen that the WO3 hollow nanotube array material doped with copper atoms has a significant response to hydrogen sulfide in a series of gases (methanol, ethanol, nitrogen dioxide, acetone, methane, hydrogen sulfide, etc.).

[0082] Application Example 2

[0083] Based on Example 3, the cycling stability of WO3 hollow nanotube array materials with different doping levels (including undoped) was compared, and the results are as follows: Figure 6 As shown, the numbers represent the amount of Cu doping; for example, 10 represents the introduction of 10 μL of copper salt, and pure represents undoped WO3 hollow nanotube array material. From Figure 6 It can be seen that, compared with the undoped WO3 hollow nanotube array material, the WO3 hollow nanotube array doped with copper atoms exhibits excellent cycling stability against hydrogen sulfide.

[0084] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A method for preparing a metal oxide hollow nanotube array material, characterized in that, Includes the following steps: S1. The substrate loaded with columnar micelle seeds is immersed in solvent A, and a block copolymer solution is added dropwise under oscillation. After static aging, rinsing and drying, a block copolymer nanobrush is obtained. S2. The block copolymer nanobrush described in S1 is immersed in a metal salt solution, washed, and then immersed again in solvent B and dried by supercritical drying to obtain a metal salt nanotube array material; the metal salt is selected from ammonium metatungstate or ethoxytantalum. S3. The metal salt nanotube array material described in S2 is calcined to obtain the metal oxide hollow nanotube array material.

2. The method for preparing the metal oxide hollow nanotube array material according to claim 1, characterized in that, In S1, the preparation method of the columnar micelle seed crystal includes the following steps: dissolving the block copolymer in solvent C and aging it at room temperature to obtain long columnar micelles; placing the long columnar micelles in an ice-water bath, ultrasonically treating them to break them, and aging them at room temperature to obtain columnar micelle seed crystals with a length of 50nm-60nm.

3. The method for preparing the metal oxide hollow nanotube array material according to claim 1, characterized in that, In S1, the method for preparing the substrate loaded with columnar micelle seeds includes the following steps: drop-coating a columnar micelle seed solution onto the substrate, followed by aging, rinsing, and drying to obtain the substrate loaded with columnar micelle seeds.

4. The method for preparing the metal oxide hollow nanotube array material according to claim 1, characterized in that, In S1, the substrate is selected from silicon dioxide, metal, glass, ceramic tube, nickel foam, plastic or carbon nanotube.

5. The method for preparing the metal oxide hollow nanotube array material according to claim 1, characterized in that, In S1, the concentration of the block copolymer solution is 1 mg / mL to 20 mg / mL; the block copolymer is selected from PFS. 24 -b-P2VP 314 PFS 27 -b-P2VP 356 and PFS 44 -b-P2VP 526 One or more of them.

6. The method for preparing the metal oxide hollow nanotube array material according to claim 1, characterized in that, In S2, the concentration of the metal salt solution is 1 mmol / L to 2 mmol / L.

7. The method for preparing the metal oxide hollow nanotube array material according to claim 1, characterized in that, In S3, the calcination temperature is 450℃-550℃, and the time is 2h-4h.

8. The method for preparing the metal oxide hollow nanotube array material according to claim 1, characterized in that, The preparation method of the metal oxide hollow nanotube array material further includes: introducing metal heteroatoms into the metal salt solution through pre-doping to obtain the doped metal oxide hollow nanotube array material.

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