CN115094621B - Sheath-core type MXene fiber aerogel and preparation method thereof - Google Patents

Sheath-core type MXene fiber aerogel and preparation method thereof Download PDF

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CN115094621B
CN115094621B CN202210780931.2A CN202210780931A CN115094621B CN 115094621 B CN115094621 B CN 115094621B CN 202210780931 A CN202210780931 A CN 202210780931A CN 115094621 B CN115094621 B CN 115094621B
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mxene
sheath
aerogel
fiber
fiber aerogel
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CN115094621A (en
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郑贤宏
李长龙
聂文琪
王宗乾
王鹏
胡侨乐
程绿竹
赵越
赵书涵
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Anhui Polytechnic University
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    • D—TEXTILES; PAPER
    • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
    • D06M—TREATMENT, NOT PROVIDED FOR ELSEWHERE IN CLASS D06, OF FIBRES, THREADS, YARNS, FABRICS, FEATHERS OR FIBROUS GOODS MADE FROM SUCH MATERIALS
    • D06M11/00—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising
    • D06M11/07—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising with halogens; with halogen acids or salts thereof; with oxides or oxyacids of halogens or salts thereof
    • D06M11/30—Treating fibres, threads, yarns, fabrics or fibrous goods made from such materials, with inorganic substances or complexes thereof; Such treatment combined with mechanical treatment, e.g. mercerising with halogens; with halogen acids or salts thereof; with oxides or oxyacids of halogens or salts thereof with oxides of halogens, oxyacids of halogens or their salts, e.g. with perchlorates
    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01D—MECHANICAL METHODS OR APPARATUS IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS
    • D01D5/00—Formation of filaments, threads, or the like
    • D01D5/28—Formation of filaments, threads, or the like while mixing different spinning solutions or melts during the spinning operation; Spinnerette packs therefor
    • D01D5/30—Conjugate filaments; Spinnerette packs therefor
    • D01D5/34—Core-skin structure; Spinnerette packs therefor
    • D—TEXTILES; PAPER
    • D01—NATURAL OR MAN-MADE THREADS OR FIBRES; SPINNING
    • D01F—CHEMICAL FEATURES IN THE MANUFACTURE OF ARTIFICIAL FILAMENTS, THREADS, FIBRES, BRISTLES OR RIBBONS; APPARATUS SPECIALLY ADAPTED FOR THE MANUFACTURE OF CARBON FILAMENTS
    • D01F8/00—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof
    • D01F8/18—Conjugated, i.e. bi- or multicomponent, artificial filaments or the like; Manufacture thereof from other substances
    • D—TEXTILES; PAPER
    • D21—PAPER-MAKING; PRODUCTION OF CELLULOSE
    • D21F—PAPER-MAKING MACHINES; METHODS OF PRODUCING PAPER THEREON
    • D21F11/00—Processes for making continuous lengths of paper, or of cardboard, or of wet web for fibre board production, on paper-making machines
    • H—ELECTRICITY
    • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
    • H05K—PRINTED CIRCUITS; CASINGS OR CONSTRUCTIONAL DETAILS OF ELECTRIC APPARATUS; MANUFACTURE OF ASSEMBLAGES OF ELECTRICAL COMPONENTS
    • H05K9/00—Screening of apparatus or components against electric or magnetic fields
    • H05K9/0073—Shielding materials
    • H05K9/0081—Electromagnetic shielding materials, e.g. EMI, RFI shielding
    • H05K9/009—Electromagnetic shielding materials, e.g. EMI, RFI shielding comprising electro-conductive fibres, e.g. metal fibres, carbon fibres, metallised textile fibres, electro-conductive mesh, woven, non-woven mat, fleece, cross-linked
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/50—Improvements relating to the production of bulk chemicals
    • Y02P20/54—Improvements relating to the production of bulk chemicals using solvents, e.g. supercritical solvents or ionic liquids

Abstract

The invention discloses a sheath-core type MXene fiber aerogel and a preparation method thereof, wherein the preparation method comprises the following steps: preparing a sheath-core type MXene composite fiber; preparing MXene composite fiber aerogel; preparing graphene/MXene composite fiber aerogel by reduction; establishing fusion anchor nodes between MXene-based composite fibers through a wet-process networking process to enhance the overall consistency and structural strength of the fiber mat and form a sheath-core graphene oxide/MXene colloidal fiber mat; and then preparing high-conductivity graphene/MXene fiber aerogel through freeze drying and reduction processes, wherein the surface of the MXene fiber is coated by high-conductivity graphene, and a layer of hydrophobic protective layer is formed on the surface of the MXene, so that the contact area between the MXene and air can be greatly reduced, the environmental stability and durability of the MXene and the electromagnetic shielding durability are improved, and the application of the flexible high-efficiency durable electromagnetic shielding material is realized.

Description

Sheath-core type MXene fiber aerogel and preparation method thereof
Technical Field
The invention relates to the technical field of electromagnetic shielding aerogel, in particular to a sheath-core type MXene fiber aerogel and a preparation method thereof.
Background
In recent years, with rapid development and application of 5G information technology and electronic products, electromagnetic waves brought by the technology not only affect precision of precision electronic equipment, but also cause electromagnetic information leakage, and even bring great threat to living environment of human beings, for example, long-term electromagnetic radiation environment can increase cardiovascular and cerebrovascular disease risks and the like. In addition, the rapid development of flexible smart wearable electronics also puts new targets and demands on flexible electromagnetic shielding materials. Therefore, development of the electromagnetic shielding material with light weight, flexibility, durability, stability and high electromagnetic shielding effectiveness is a basic guarantee for meeting development requirements of flexible intelligent wearable electronic devices.
At present, a flexible conductive electromagnetic shielding material is usually obtained by adopting methods of coating, chemical plating, electroplating and the like on a film or a flexible fabric substrate, however, the prepared electromagnetic shielding material has lower electromagnetic shielding efficiency due to poor conductivity of the fabric substrate, and the problems of low coating fastness, worsening air permeability and moisture permeability and the like of the electromagnetic shielding active material are caused. Aerogel materials are considered to be ideal electromagnetic shielding materials because of their low density, developed pore structure, low specific surface area, and the like. MXene is a novel two-dimensional layered nanomaterial with superior dispersibility, processability, conductivity, and electromagnetic shielding effectiveness over carbon materials (116dB,Iqbal et al, science,2020, 369, 446-450). Therefore, the preparation of the MXene into the aerogel is expected to obtain a material with high electromagnetic shielding effectiveness.
However, MXene is extremely prone to absorb moisture in a humid environment due to its abundant functional groups and surface termination nodes, resulting in oxidation and cleavage of the lamellar structure to form titanium dioxide, ultimately leading to material performance degradation and loss of function. At present, methods such as antioxidant treatment, surfactant modification, heat treatment, polymer encapsulation and the like are generally adopted to inhibit the oxidation of the MXene, but the preparation process is complex, and the application performance of the modified MXene material can be influenced by the reduction of the conductivity of the modified MXene material. Therefore, developing an efficient and durable electromagnetic shielding MXene aerogel without deteriorating the conductivity of the MXene material remains a significant challenge; therefore, a sheath-core type MXene fiber aerogel and a preparation method thereof are provided for solving the problems.
Disclosure of Invention
In order to overcome the defects in the prior art and solve at least one problem, the invention provides a sheath-core type MXene fiber aerogel and a preparation method thereof.
The preparation method of the sheath-core type MXene fiber aerogel comprises the following steps:
step S1: preparing a sheath-core type MXene composite fiber;
step S2: preparing MXene composite fiber aerogel;
step S3: and (3) preparing graphene/MXene composite fiber aerogel through reduction.
Preferably, in step S1, the method for preparing the sheath-core MXene composite fiber is as follows: taking MXene dispersion liquid as core layer spinning liquid, taking graphene oxide as skin layer spinning liquid, taking a coaxial needle with the inner diameter of 0.16-2.27 mm and the outer diameter of 0.31-2.77 mm as a spinneret orifice, injecting the skin layer and core layer spinning liquid into a coagulating bath at the speed of 0.5-600 mL/h to prepare a primary spinning colloid fiber, coagulating the primary spinning colloid fiber in the coagulating bath for 0.5-10 minutes, and transferring the primary spinning colloid fiber into an ethanol aqueous solution.
Preferably, in the step S1, the concentration of the MXene dispersion is selected to be 0.01 to 20wt%; the concentration of the graphene oxide is selected to be 0.01-20wt%; wherein the coagulating bath is 0.5-10wt% CaCl 2 、0.5～10wt％ZnCl 2 、0.5～10wt％MgCl 2 0.5 to 10 weight percent of NaCl, absolute ethyl alcohol, 0.1 to 5 percent of chitosan and 20 to 99 percent of acetic acid solution.
Preferably, in the step S2, 5-200 g of the colloidal fiber prepared in the step S1 is prepared into a colloidal fiber felt with a thickness of 0.2-20 mm by a wet-laid method, and then the colloidal fiber felt is washed 1-3 times to sufficiently remove the residual coagulant in the colloidal fiber felt; the colloid fiber felt is firstly dried for 0.5-10 minutes at 30-70 ℃, and then is prepared into the MXene composite fiber aerogel by a freeze drying or supercritical carbon dioxide drying method.
Preferably, in the step S2, in the method of freeze-drying or supercritical carbon dioxide drying, the freeze-drying temperature is controlled to be-30 ℃ to-100 ℃ and the freeze-drying time is controlled to be 5-24 hours; the flow rate of the carbon dioxide fluid used for supercritical carbon dioxide drying is 500-3000L/h, the pressure is 1-20MPa, and the supercritical drying time is 1-20 minutes.
Preferably, in the step S3, the MXene composite fiber aerogel prepared in the step S2 is chemically reduced or thermally treated to obtain a high-conductivity graphene/MXene composite fiber aerogel, wherein the chemical reduction is performed by using 10-55wt% of hydroiodic acid, 1-80wt% of hydrazine hydrate, 1-40wt% of vitamin C, and 1-40wt% of sodium bisulphite, and the chemical reduction temperature is 50-95 ℃ and the chemical reduction time is 0.1-8h; the heat treatment temperature is 220-1500 ℃ and the heat treatment time is 0.1-5h.
A sheath-core MXene fiber aerogel prepared by the method of any one of claims 1-6, the MXene fiber aerogel being used in the fields of thermal insulation, pressure sensing, and oil-water separation.
The invention has the advantages that:
according to the invention, the sheath-core graphene oxide/MXene composite fiber is prepared by a coaxial spinning method, and fusion anchor nodes are established between the MXene-based composite fibers by a wet-process networking process by means of good fusion characteristics and easy adhesion characteristics of the sheath-core graphene oxide so as to enhance the overall consistency and structural strength of the fiber felt and form the sheath-core graphene oxide/MXene colloidal fiber felt; and then preparing high-conductivity graphene/MXene fiber aerogel through freeze drying and reduction processes, wherein the surface of the MXene fiber is coated by high-conductivity graphene, and a layer of hydrophobic protective layer is formed on the surface of the MXene, so that the water absorption of the MXene composite fiber can be reduced, the contact area between the MXene and air can be greatly reduced, the environmental stability and durability of the MXene and the electromagnetic shielding durability can be improved, and the application of the flexible high-efficiency durable electromagnetic shielding material can be realized.
The invention develops a high-efficiency durable MXene-based fiber aerogel material based on a coaxial spinning technology and a wet-process web-forming technology, which has the following advantages:
1. the popularization is strong. The composite fiber cortex adopted by the invention can be PEDOT: PSS, carbon nanotubes, PDMS, carboxymethyl cellulose, polyvinyl alcohol, etc.
2. By utilizing the fusion riveting effect of the cortex graphene oxide, the integral consistency of the MXene-based fiber aerogel structure is improved, the stress dispersion transfer in the stress process is facilitated, and the prepared MXene-based fiber aerogel has excellent compression performance and compression recovery performance.
3. The method has the advantages of simple process, easy realization, low production cost and suitability for mass production.
4. The sheath-core type MXene-based fiber aerogel prepared by the method has the advantages of low density, developed pores, strong hydrophobicity and high conductivity; the skin-core type MXene-based fiber aerogel prepared by the method has excellent electromagnetic shielding performance, the electromagnetic shielding efficiency can reach 90dB, and an electromagnetic shielding mechanism mainly based on wave absorption is shown, so that secondary pollution of electromagnetic waves can be fully reduced; the performance of the sheath-core MXene-based fiber aerogel prepared by the method is adjustable and controllable, and the performance of the sheath-core MXene-based fiber aerogel can be adjusted by adjusting the thickness, the diameter of a spinneret orifice, the area density and the volume density of the aerogel; due to the protective effect of the cortical graphene, the moisture absorption, oxidation and degradation of the MXene are inhibited, and the prepared sheath-core MXene-based fiber aerogel has excellent electromagnetic shielding durability, and after 6 months, the retention rate of electromagnetic shielding efficiency can reach 85%.
5. The application range is wide. The skin-core type MXene-based fiber aerogel prepared by the invention can be used in the fields of heat preservation and insulation, pressure sensing, oil-water separation and the like.
Drawings
In order to more clearly illustrate the embodiments of the invention or the technical solutions of the prior art, the drawings which are used in the description of the embodiments or the prior art will be briefly described, it being obvious that the drawings in the description below are only some embodiments of the invention, and that other drawings can be obtained from these drawings without inventive faculty for a person skilled in the art.
FIG. 1 is a diagram showing the practical examples of the present invention 1 and comparative example 1;
FIG. 2 is a diagram of the embodiment 7;
FIG. 3 is a microscopic view of example 1, example 7 and comparative example 1;
FIG. 4 is the water contact angle for example 7 and comparative example 1;
FIG. 5 is a diagram of the compression recovery object of example 7;
FIG. 6 is a fiber scanning electron microscope, energy spectrum and aerogel scanning electron microscope of the preparation of example 7;
FIG. 7 shows the electromagnetic shielding performance of examples 1-7;
fig. 8 is electromagnetic shielding properties of example 5 and comparative examples 2 to 4;
fig. 9 is electromagnetic shield durability of example 7 and comparative example 5;
FIG. 10 is an electromagnetic shielding mechanism of examples 1-7;
FIG. 11 is a diagram showing the oil-water separation of example 1.
Detailed Description
The following description of the embodiments of the present invention will be made clearly and completely with reference to the accompanying drawings, in which it is apparent that the embodiments described are only some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
The preparation method of the sheath-core type MXene fiber aerogel comprises the following steps:
step S1: preparing a sheath-core type MXene composite fiber;
step S2: preparing MXene composite fiber aerogel;
step S3: and (3) preparing graphene/MXene composite fiber aerogel through reduction.
As an embodiment of the present invention, in step S1, the method for preparing the sheath-core MXene composite fiber is as follows: taking MXene dispersion liquid as core layer spinning liquid, taking graphene oxide as skin layer spinning liquid, taking a coaxial needle with the inner diameter of 0.16-2.27 mm and the outer diameter of 0.31-2.77 mm as a spinneret orifice, injecting the skin layer and core layer spinning liquid into a coagulating bath at the speed of 0.5-600 mL/h to prepare a primary spinning colloid fiber, coagulating the primary spinning colloid fiber in the coagulating bath for 0.5-10 minutes, and transferring the primary spinning colloid fiber into an ethanol aqueous solution.
As one embodiment of the present invention, in the step S1, the concentration of the MXene dispersion is selected as0.01 to 20wt percent; the concentration of the graphene oxide is selected to be 0.01-20wt%; wherein the coagulating bath is 0.5-10wt% CaCl 2 、0.5～10wt％ZnCl 2 、0.5～10wt％MgCl 2 0.5 to 10 weight percent of NaCl, absolute ethyl alcohol, 0.1 to 5 percent of chitosan and 20 to 99 percent of acetic acid solution.
In the step S2, 5-200 g of the colloidal fiber prepared in the step S1 is prepared into a colloidal fiber felt with the thickness of 0.2-20 mm by a wet-laid method, and then the residual coagulant in the colloidal fiber felt is sufficiently removed by washing for 1-3 times; the colloid fiber felt is firstly dried for 0.5-10 minutes at 30-70 ℃, and then is prepared into the MXene composite fiber aerogel by a freeze drying or supercritical carbon dioxide drying method.
In the step S2, the freeze-drying or supercritical carbon dioxide drying method is performed at a freeze-drying temperature of-30 ℃ to-100 ℃ for 5 to 24 hours; the flow rate of the carbon dioxide fluid used for supercritical carbon dioxide drying is 500-3000L/h, the pressure is 1-20MPa, and the supercritical drying time is 1-20 minutes.
In the step S3, the MXene composite fiber aerogel prepared in the step S2 is subjected to chemical reduction or heat treatment to obtain the high-conductivity graphene/MXene composite fiber aerogel, wherein 10-55wt% of hydroiodic acid, 1-80wt% of hydrazine hydrate, 1-40wt% of vitamin C and 1-40wt% of sodium bisulphite are adopted in the chemical reduction, and the chemical reduction temperature is 50-95 ℃ for 0.1-8h; the heat treatment temperature is 220-1500 ℃ and the heat treatment time is 0.1-5h.
A sheath-core MXene fiber aerogel prepared by the method of any one of claims 1-6, the MXene fiber aerogel being used in the fields of thermal insulation, pressure sensing, and oil-water separation.
Specific examples are given below:
example 1
The preparation method of the sheath-core type MXene fiber aerogel comprises the following steps:
1. preparation of sheath-core type MXene composite fiber: taking MXene dispersion liquid with the concentration of 20wt% as core layer spinning solution, taking graphene oxide with the concentration of 1wt% as skin layer spinning solution, taking a coaxial needle with the inner diameter of 0.23mm and the outer diameter of 0.7mm as a spinneret orifice, and injecting the core layer spinning solution and the outer layer spinning solution into 5wt% MgCl at the speeds of 1mL/h and 0.5mL/h respectively 2 In the coagulation bath, the as-spun colloidal fibers were coagulated in the coagulation bath for 10 minutes and then transferred to an aqueous ethanol solution.
2. Preparation of sheath-core type MXene composite fiber aerogel: the colloidal fiber prepared in the step 1 was prepared into a colloidal fiber blanket having a thickness of 1mm by a wet-laid method, and then washed 3 times to sufficiently remove the residual coagulant in the colloidal fiber blanket, and the colloidal fiber blanket was first dried at 50 ℃ for 5 minutes, and then freeze-dried at-50 ℃ for 24 hours, to prepare a sheath-core type MXene composite fiber aerogel.
3. Preparing graphene/MXene composite fiber aerogel by reduction: the sheath-core type MXene composite fiber aerogel prepared in the step 2 is reduced by 45wt% of hydroiodic acid at 90 ℃ for 4 hours.
As can be seen from fig. 11, the embodiment can almost completely absorb the pump oil, and exhibits good oil-water separation performance.
Example 2
The preparation method of the sheath-core type MXene fiber aerogel comprises the following steps:
1. preparation of sheath-core type MXene composite fiber: taking MXene dispersion liquid with the concentration of 20wt% as core layer spinning solution, taking graphene oxide with the concentration of 1wt% as skin layer spinning solution, taking a coaxial needle with the inner diameter of 0.23mm and the outer diameter of 0.7mm as a spinneret orifice, and injecting the core layer spinning solution and the outer layer spinning solution into 5wt% MgCl at the speeds of 1mL/h and 0.5mL/h respectively 2 In the coagulation bath, the as-spun colloidal fibers were coagulated in the coagulation bath for 10 minutes and then transferred to an aqueous ethanol solution.
2. Preparation of sheath-core type MXene composite fiber aerogel: the colloidal fiber prepared in the step 1 was prepared into a colloidal fiber blanket having a thickness of 2mm by a wet-laid method, and then washed 3 times to sufficiently remove the residual coagulant in the colloidal fiber blanket, and the colloidal fiber blanket was first dried at 50 ℃ for 5 minutes, and then freeze-dried at-50 ℃ for 24 hours, to prepare a sheath-core type MXene composite fiber aerogel.
3. Preparing graphene/MXene composite fiber aerogel by reduction: the sheath-core type MXene composite fiber aerogel prepared in the step 2 is reduced by 45wt% of hydroiodic acid at 90 ℃ for 4 hours.
Example 3
The preparation method of the sheath-core type MXene fiber aerogel comprises the following steps:
1. preparation of sheath-core type MXene composite fiber: taking MXene dispersion liquid with the concentration of 20wt% as core layer spinning solution, taking graphene oxide with the concentration of 1wt% as skin layer spinning solution, taking a coaxial needle with the inner diameter of 0.23mm and the outer diameter of 0.7mm as a spinneret orifice, and injecting the core layer spinning solution and the outer layer spinning solution into 5wt% MgCl at the speeds of 1mL/h and 0.5mL/h respectively 2 In the coagulation bath, the as-spun colloidal fibers were coagulated in the coagulation bath for 10 minutes and then transferred to an aqueous ethanol solution.
2. Preparation of sheath-core type MXene composite fiber aerogel: the colloidal fiber prepared in the step 1 was prepared into a colloidal fiber blanket having a thickness of 3mm by a wet-laid method, and then washed 3 times to sufficiently remove the residual coagulant in the colloidal fiber blanket, and the colloidal fiber blanket was first dried at 50 ℃ for 5 minutes, and then freeze-dried at-50 ℃ for 24 hours, to prepare a sheath-core type MXene composite fiber aerogel.
3. Preparing graphene/MXene composite fiber aerogel by reduction: the sheath-core type MXene composite fiber aerogel prepared in the step 2 is reduced by 45wt% of hydroiodic acid at 90 ℃ for 4 hours.
Example 4
The preparation method of the sheath-core type MXene fiber aerogel comprises the following steps:
1. preparation of sheath-core type MXene composite fiber: taking MXene dispersion liquid with the concentration of 20wt% as core layer spinning solution, taking graphene oxide with the concentration of 1wt% as skin layer spinning solution, taking a coaxial needle with the inner diameter of 0.23mm and the outer diameter of 0.7mm as a spinneret orifice, and injecting the core layer spinning solution and the outer layer spinning solution into 5wt% MgCl at the speeds of 1mL/h and 0.5mL/h respectively 2 In coagulation bath, spinning gelThe bulk fibers were coagulated in a coagulation bath for 10 minutes and then transferred to an aqueous ethanol solution.
2. Preparation of sheath-core type MXene composite fiber aerogel: the colloidal fiber prepared in the step 1 was prepared into a colloidal fiber blanket having a thickness of 4mm by a wet-laid method, and then washed 3 times to sufficiently remove the residual coagulant in the colloidal fiber blanket, and the colloidal fiber blanket was first dried at 50 ℃ for 5 minutes, and then freeze-dried at-50 ℃ for 24 hours, to prepare a sheath-core type MXene composite fiber aerogel.
3. Preparing graphene/MXene composite fiber aerogel by reduction: the sheath-core type MXene composite fiber aerogel prepared in the step 2 is reduced by 45wt% of hydroiodic acid at 90 ℃ for 4 hours.
Example 5
The preparation method of the sheath-core type MXene fiber aerogel comprises the following steps:
1. preparation of sheath-core type MXene composite fiber: taking MXene dispersion liquid with the concentration of 20wt% as core layer spinning solution, taking graphene oxide with the concentration of 1wt% as skin layer spinning solution, taking a coaxial needle with the inner diameter of 0.23mm and the outer diameter of 0.7mm as a spinneret orifice, and injecting the core layer spinning solution and the outer layer spinning solution into 5wt% MgCl at the speeds of 1mL/h and 0.5mL/h respectively 2 In the coagulation bath, the as-spun colloidal fibers were coagulated in the coagulation bath for 10 minutes and then transferred to an aqueous ethanol solution.
2. Preparation of sheath-core type MXene composite fiber aerogel: the colloidal fiber prepared in the step 1 was prepared into a colloidal fiber blanket having a thickness of 5mm by a wet-laid method, and then washed 3 times to sufficiently remove the residual coagulant in the colloidal fiber blanket, and the colloidal fiber blanket was first dried at 50 ℃ for 5 minutes, and then freeze-dried at-50 ℃ for 24 hours, to prepare a sheath-core type MXene composite fiber aerogel.
3. Preparing graphene/MXene composite fiber aerogel by reduction: the sheath-core type MXene composite fiber aerogel prepared in the step 2 is reduced by 45wt% of hydroiodic acid at 90 ℃ for 4 hours.
Example 6
The preparation method of the sheath-core type MXene fiber aerogel comprises the following steps:
1. preparation of sheath-core type MXene composite fiber: taking MXene dispersion liquid with the concentration of 20wt% as core layer spinning solution, taking graphene oxide with the concentration of 1wt% as skin layer spinning solution, taking a coaxial needle with the inner diameter of 0.23mm and the outer diameter of 0.7mm as a spinneret orifice, and injecting the core layer spinning solution and the outer layer spinning solution into 5wt% MgCl at the speeds of 1mL/h and 0.5mL/h respectively 2 In the coagulation bath, the as-spun colloidal fibers were coagulated in the coagulation bath for 10 minutes and then transferred to an aqueous ethanol solution.
2. Preparation of sheath-core type MXene composite fiber aerogel: the colloidal fiber prepared in the step 1 was prepared into a colloidal fiber blanket having a thickness of 6mm by a wet-laid method, and then washed 3 times to sufficiently remove the residual coagulant in the colloidal fiber blanket, and the colloidal fiber blanket was first dried at 50 ℃ for 5 minutes, and then freeze-dried at-50 ℃ for 24 hours, to prepare a sheath-core type MXene composite fiber aerogel.
3. Preparing graphene/MXene composite fiber aerogel by reduction: the sheath-core type MXene composite fiber aerogel prepared in the step 2 is reduced by 45wt% of hydroiodic acid at 90 ℃ for 4 hours.
Example 7
The preparation method of the sheath-core type MXene fiber aerogel comprises the following steps:
1. preparation of sheath-core type MXene composite fiber: taking MXene dispersion liquid with the concentration of 20wt% as core layer spinning solution, taking graphene oxide with the concentration of 1wt% as skin layer spinning solution, taking a coaxial needle with the inner diameter of 0.23mm and the outer diameter of 0.7mm as a spinneret orifice, and injecting the core layer spinning solution and the outer layer spinning solution into 5wt% MgCl at the speeds of 1mL/h and 0.5mL/h respectively 2 In the coagulation bath, the as-spun colloidal fibers were coagulated in the coagulation bath for 10 minutes and then transferred to an aqueous ethanol solution.
2. Preparation of sheath-core type MXene composite fiber aerogel: the colloidal fiber prepared in the step 1 was prepared into a colloidal fiber blanket having a thickness of 7mm by a wet-laid method, and then washed 3 times to sufficiently remove the residual coagulant in the colloidal fiber blanket, and the colloidal fiber blanket was first dried at 50 ℃ for 5 minutes, and then freeze-dried at-50 ℃ for 24 hours, to prepare a sheath-core type MXene composite fiber aerogel.
3. Preparing graphene/MXene composite fiber aerogel by reduction: the sheath-core type MXene composite fiber aerogel prepared in the step 2 is reduced by 45wt% of hydroiodic acid at 90 ℃ for 4 hours.
As can be seen from fig. 2, example 7, which is small in density and light in weight, can be suspended on the pistil and dandelion without causing deformation of the pistil and dandelion, and exhibits light weight characteristics;
as can be seen from fig. 5, the thickness of example 7 was 4mm after compression of the 100g weight, and the thickness of the fibrous aerogel after compression was still 7mm, exhibiting excellent compression resilience. The excellent compression performance and compression recovery performance of the sheath-core MXene fiber-based aerogel prepared by the invention are mainly attributed to the Y-shaped connection of the fiber aerogel, so that the fiber aerogel has better overall consistency, and stress is dispersed by effectively transmitting stress in the compression stress process;
as can be seen from fig. 6, the MXene fiber prepared in example 7 exhibits a zigzag interface structure and has an obvious sheath-core structure, the core layer is MXene fiber, and the sheath layer is fully wrapped with graphene; in addition, the MXene-based fiber aerogel prepared in example 7 was composed of fibers bonded to each other to form a "Y" shape bond, and had a large number of pore structures inside the aerogel;
as can be seen from fig. 7, in the X-band, the average electromagnetic shielding effectiveness of example 1 is only 16.53dB, the average electromagnetic shielding effectiveness of example 7 is highest, up to 83dB, and a part of the frequency band may exceed 90dB, mainly because the thickness of example 1 is the smallest (1 mm), the thickness of example 7 is the highest (7 mm), and a higher material thickness will cause more electromagnetic waves to be absorbed. Furthermore, it can be seen from the graph that the absorption Shielding Effectiveness (SE) of examples 1 to 7 A ) Far higher than the reflection Shielding Effectiveness (SE) R ) The skin-core type MXene-based fiber aerogel prepared by the invention shows an electromagnetic shielding mechanism mainly based on absorption, which is mainly because the skin-core type MXene-based fiber aerogel has better impedance matching effect, a small amount of electromagnetic waves are reflected, most of the electromagnetic waves enter the inside of the fiber, and the absorbed electromagnetic waves are converted into the electromagnetic waves through interface polarization effect, dielectric loss and ohmic loss effect in the inside of the fiberIs converted into heat. The electromagnetic shielding mechanism mainly based on absorption of the skin-core type MXene-based fiber aerogel prepared by the invention is beneficial to reducing secondary pollution of electromagnetic radiation;
as can be seen from fig. 10, the electromagnetic shielding mechanism of examples 1-7 is electromagnetic wave absorption, which is mainly derived from the better impedance matching effect of the fiber aerogel and the medium, so that a small amount of electromagnetic waves are reflected, most of the electromagnetic waves enter the inside of the aerogel, and the electromagnetic waves enter the inside of the fiber aerogel to be subjected to multiple reflection attenuation, conduction loss and polarization loss effects, so that the energy of the incoming electromagnetic waves is converted into heat.
Comparative example 1
As shown in fig. 1, 3 and 4, a method for preparing a sheath-core MXene fiber aerogel, the method comprising the steps of:
preparation of MXene fibers: as in example 1, only the MXene dope was prepared by wet spinning without using the coaxial spinning method.
Preparation of MXene fiber aerogel: the same as in example 1.
As can be seen from fig. 1, the fibers of the embodiment 1 are bonded with each other to form a whole, the structure is uniform and compact, and the consistency of the whole aerogel is good; comparative example 1 the fibers were loose and failed to form a monolithic aerogel. The graphene oxide introduced by the coaxial wet spinning adopted by the method has a good fusion effect, and fibers are mutually bonded to form a net structure so as to improve the structural integrity and consistency of the fiber aerogel;
as can be seen from fig. 3, the fibers in the fibrous aerogels of example 1 and example 7 are bonded to each other to form a Y-shaped bond, which gives the fibrous aerogel a better structural integrity, while the fibers in comparative example 1 have no riveting action, and the aerogel has a single fiber state inside;
as can be seen from fig. 4, the water contact angle of example 7 is 144.7 °, having excellent hydrophobic properties; the water contact angle of comparative example 1 was 81.0 °, exhibiting hydrophilicity. The excellent hydrophobicity of example 7 is mainly due to the hydrophobicity of the cortical graphene.
Comparative example 2
As shown in fig. 8, a method for preparing a sheath-core MXene fiber aerogel, the method comprising the steps of:
1. preparation of sheath-core type MXene composite fiber: the same as in example 1.
2. Preparation of sheath-core type MXene composite fiber aerogel: the same as in example 1, except that the area density of the fibrous aerogel was increased to 13.3mg/cm 2 。
Wherein, the graphene/MXene composite fiber aerogel is prepared by reduction: the same as in example 1.
Comparative example 3
As shown in fig. 8, a method for preparing a sheath-core MXene fiber aerogel, the method comprising the steps of:
1. preparation of sheath-core type MXene composite fiber: the same as in example 1.
2. Preparation of sheath-core type MXene composite fiber aerogel: the same as in example 1, except that the area density of the fibrous aerogel was increased to 15.7mg/cm 2 。
Wherein, the graphene/MXene composite fiber aerogel is prepared by reduction: the same as in example 1.
Comparative example 4
As shown in fig. 8, a method for preparing a sheath-core MXene fiber aerogel, the method comprising the steps of:
1. preparation of sheath-core type MXene composite fiber: the same as in example 1.
2. Preparation of sheath-core type MXene composite fiber aerogel: the same as in example 1, except that the area density of the fibrous aerogel was increased to 18.9mg/cm 2 。
Wherein, the graphene/MXene composite fiber aerogel is prepared by reduction: the same as in example 1.
As can be seen from fig. 8, the total electromagnetic shielding effectiveness of example 5 is the lowest and the electromagnetic shielding effectiveness of comparative example 4 is the highest under the same thickness of the fibrous aerogel (5 mm), i.e., the electromagnetic shielding performance of the fibrous aerogel increases with increasing area density, mainly because at the same thickness, higher area density means higher bulk density and higher percentage of conductive filler content of the fibrous aerogel results in more electromagnetic wave absorption.
Comparative example 5
As shown in fig. 9, a method for preparing a sheath-core MXene fiber aerogel, the method comprising the steps of:
1. 31.1mL of a 1wt% MXene dispersion was vacuum filtered for 1 hour;
wherein the film prepared in step 1 is dried at 60 ℃ for 5 minutes to obtain the film with the area density of 24.7mg/cm 2 Is a film of (a).
As can be seen from fig. 9, example 7 has an electromagnetic shielding effectiveness retention rate as high as 85% after 6 months, whereas comparative example 5 has an electromagnetic shielding effectiveness retention rate of only 48.4%, and example 7 exhibits excellent electromagnetic shielding durability, which is mainly attributed to the better hydrophobicity and protection of the skin layer MXene, and can reduce the contact area of the core layer MXene and improve the oxidation resistance thereof.
In the description of the present specification, the descriptions of the terms "one embodiment," "example," "specific example," and the like, mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiments or examples. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
The foregoing has shown and described the basic principles, principal features and advantages of the invention. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, and that the above embodiments and descriptions are merely illustrative of the principles of the present invention, and various changes and modifications may be made without departing from the spirit and scope of the invention, which is defined in the appended claims.

Claims (5)

1. A preparation method of sheath-core type MXene fiber aerogel is characterized by comprising the following steps: the preparation method comprises the following steps:
step S1, preparing a skin-core type MXene composite fiber, wherein the preparation method of the skin-core type MXene composite fiber comprises the following steps: taking MXene dispersion liquid as core layer spinning liquid, taking graphene oxide as skin layer spinning liquid, taking a coaxial needle with the inner diameter of 0.16-2.27 mm and the outer diameter of 0.31-2.77 mm as a spinneret orifice, injecting the skin layer and core layer spinning liquid into a coagulating bath at the speed of 0.5-600 mL/h to prepare primary spinning colloid fibers, solidifying the primary spinning colloid fibers in the coagulating bath for 0.5-10 minutes, and transferring the primary spinning colloid fibers into ethanol water solution;
s2, preparing MXene composite fiber aerogel, namely preparing 5-200 g of colloid fibers prepared in the step S1 into a colloid fiber felt with the thickness of 0.2-20 mm by a wet-laid method, and then washing for 1-3 times to fully remove residual coagulant in the colloid fiber felt; the colloid fiber felt is firstly dried for 0.5 to 10 minutes at the temperature of between 30 and 70 ℃ and then is prepared into the MXene composite fiber aerogel by a freeze drying or supercritical carbon dioxide drying method;
s3, preparing graphene/MXene composite fiber aerogel by reduction; and obtaining the high-conductivity graphene/MXene composite fiber aerogel by adopting the MXene composite fiber aerogel and adopting a chemical reduction or heat treatment mode.
2. The method for preparing the sheath-core type MXene fiber aerogel according to claim 1, which is characterized in that: in the step S1, the concentration of the MXene dispersion liquid is selected to be 0.01-20wt%; the concentration of the graphene oxide is selected to be 0.01-20wt%; wherein the coagulating bath is one or more of 0.5-10wt% of CaCl2, 0.5-10wt% of ZnCl2, 0.5-10wt% of MgCl2, 0.5-10wt% of NaCl, absolute ethyl alcohol, 0.1-5% of chitosan and 20-99% of acetic acid solution.
3. The method for preparing the sheath-core type MXene fiber aerogel according to claim 2, which is characterized in that: in the step S2, in the freeze drying or supercritical carbon dioxide drying method, the freeze drying temperature is controlled to be minus 30 ℃ to minus 100 ℃ and the freeze drying time is controlled to be 5-24 hours; the flow rate of the carbon dioxide fluid used for supercritical carbon dioxide drying is 500-3000L/h, the pressure is 1-20MPa, and the supercritical drying time is 1-20 minutes.
4. The method for preparing the sheath-core type MXene fiber aerogel according to claim 3, wherein the method comprises the following steps: in the step S3, the MXene composite fiber aerogel prepared in the step S2 is subjected to chemical reduction or heat treatment to obtain the high-conductivity graphene/MXene composite fiber aerogel, wherein the chemical reduction adopts at least one of 10-55wt% of hydroiodic acid, 1-80wt% of hydrazine hydrate, 1-40wt% of vitamin C and 1-40wt% of sodium bisulphite, and the chemical reduction temperature is 50-95 ℃ and the time is 0.1-8h; the heat treatment temperature is 220-1500 ℃ and the heat treatment time is 0.1-5h.
5. A sheath-core MXene fiber aerogel prepared by the method of any one of claims 1-4, characterized in that: the MXene fiber aerogel is applied to the fields of heat preservation, heat insulation, pressure sensing and oil-water separation.
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