CN114436261A

CN114436261A - Two-dimensional Ti3C2TxSelf-crimping fiber of material, preparation method and application thereof

Info

Publication number: CN114436261A
Application number: CN202210216395.3A
Authority: CN
Inventors: 张青; 曹金鑫
Original assignee: Anhui University
Current assignee: Anhui University
Priority date: 2022-03-07
Filing date: 2022-03-07
Publication date: 2022-05-06
Anticipated expiration: 2042-03-07
Also published as: CN114436261B

Abstract

The invention relates to the technical field of fiber materials, in particular to two-dimensional Ti₃C₂T_xSelf-curling fiber of material, preparation method and application thereof, mixing LiF and HCl to Ti₃AlC₂Etching is carried out, and Ti with thickness distribution concentrated in one to two layers is prepared by the method₃C₂T_xA material; the obtained Ti₃C₂T_xDispersing in water, adding L-ascorbic acid, performing ultrasonic treatment under argon gas as protective gas and ice bath, and freeze drying to obtain Ti₃C₂T_xFiber, which solves the problem of rigid two-dimensional Ti which is not available at present₃C₂T_xThe sheet self-curls into a compact structureThe fiber material of (2).

Description

Two-dimensional Ti3C2TxSelf-crimping fiber of material, preparation method and application thereof

Technical Field

The invention relates to the technical field of fiber materials, in particular to two-dimensional Ti₃C₂T_xSelf-crimping fiber of a material, a preparation method and application thereof.

Background

MXene is a new layered two-dimensional material etched from its corresponding MAX phase, typically M_n+1X_nT_xWherein M represents a transition metal, such as Ti, V; a represents etched elements such as Al and Si; x represents C or N; t is_xAre surface functional groups, such as-O, -OH, -F (n ═ 1,2, 3). Wherein Ti₃C₂T_xIs the earliest quiltThe MXene material is also a widely researched MXene material, is formed by interleaving 3 layers of titanium atoms and 2 layers of carbon atoms, has excellent conductivity, hydrophilicity and abundant surface functional groups, and has wide application prospects in the aspects of electrochemical energy storage, electrocatalysis and the like. In order to realize these applications, it is necessary to develop different preparation processes of Ti₃C₂T_xThe material is prepared into different structures, such as films, sponges, fibers and the like, so as to meet the specific application requirements; among them, the fiber is a material form with strong plasticity, and because of its characteristics of softness, weaving, etc., it is suitable for preparing flexible electronic devices and has received general attention.

So far, Ti was prepared₃C₂T_xThe fiber may be produced by a finish coating method, electrostatic spinning, wet spinning, or the like. Wherein the fibers obtained by the finish coating method are not pure Ti₃C₂T_xFibers other than Ti₃C₂T_xAs a coating material, to other fiber materials, such as glass fiber, etc. Electrospinning is generally carried out by subjecting Ti₃C₂T_xMixing with electrospun polymer material (such as PAN, PCL) and carbon nanotube or carbon fiber material, and spinning to obtain Ti-containing material₃C₂T_xThe fibers of (1). Wet spinning Ti₃C₂T_xMixing with other easily spinnable substances, such as PEDOT, graphene, etc., and coagulating and drying by pushing the mixed solution into coagulating bath via syringe to obtain the product containing Ti₃C₂T_xThe fibers of (1). It is particularly worth mentioning that at present by using Ti₃C₂T_xPure Ti can be obtained by the liquid crystal state characteristic of the concentrated solution and wet spinning₃C₂T_xFibers, but in the fibers, Ti₃C₂T_xThe two-dimensional flake morphology is maintained, self-curling does not occur, the diameter of the obtained fiber is generally tens of microns or even tens of microns, and nano-scale Ti cannot be obtained₃C₂T_xA fiber.

At Ti₃C₂T_xDue to the single layer of Ti₃C₂T_xThe graphene is composed of 3 layers of titanium atoms and 2 layers of carbon atoms, has higher mechanical strength compared with graphene composed of only a single layer of carbon atoms, and has very high difficulty in realizing self-curling of a sheet layer. At present, only Ti consisting of 2 layers of titanium atoms and 1 layer of carbon atoms is available₂CT_xThe material adopts the report of a spray freeze-drying method, and Ti with a hollow tubular structure can be obtained₂CT_xAnd treating the resulting Ti under the same conditions₃C₂T_xThe shape of the hollow sphere only shows that the curling difficulty of MXene increases with the increase of the number of layers of the monolayer composition atoms. Studies in the prior art have shown that Ti₃C₂T_xThe hollow coiled structure can be obtained by ultrasonic treatment and freeze drying for one week under the alkaline condition, but the structure is loose. In view of the foregoing, there is currently no way to make rigid two-dimensional Ti₃C₂T_xThe sheet self-curls into a tightly structured fibrous material.

In view of the above-mentioned drawbacks, the inventors of the present invention have finally obtained the present invention through a long period of research and practice.

Disclosure of Invention

The invention aims to solve the problem that no method for enabling rigid two-dimensional Ti to exist at present₃C₂T_xThe problem of sheet self-curling into a compact structured fibrous material provides a two-dimensional Ti₃C₂T_xA method for preparing self-crimping fibers of a material.

In order to achieve the aim, the invention discloses a preparation method of a self-crimping fiber of a two-dimensional Ti3C2Tx material, which comprises the following steps: to Ti₃C₂T_xAdding L-ascorbic acid into the aqueous solution, performing ultrasonic treatment under the condition of argon as protective gas and ice bath, and freeze-drying to obtain a freeze-dried product, namely Ti₃C₂T_xFiber MXene-L_x％The sponge-like product is formed, wherein x% is the mass ratio of the L-ascorbic acid.

The x% is more than or equal to 50%.

The ultrasonic power is 100-300W, and the ultrasonic time is 5-60 min.

The Ti₃C₂T_xThe preparation method of the solution is as follows: using a Ti as disclosed in the prior art₃C₂T_xThe preparation method of the material is that LiF and HCl are mixed to Ti₃AlC₂Etching is carried out, and Ti obtained by the method₃C₂T_xThe thickness of the material is concentrated and distributed in 1-2 layers, namely 3 nm.

The invention also discloses a two-dimensional Ti prepared by the preparation method₃C₂T_xThe self-curling fiber of the material has greatly improved mechanical performance and may be used in electronic device, such as super capacitor.

Compared with the prior art, the invention has the beneficial effects that: the invention successfully induces the rigid Ti by adding the L-ascorbic acid and matching with the ultrasonic freeze-drying treatment₃C₂T_xThe two-dimensional material is spontaneously curled into a fiber structure, the operation is simple, the time consumption is short, the obtained fiber structure is compact, the fiber with the nanometer diameter can be obtained by adopting the method, the diameter is adjustable, and the obtained Ti is₃C₂T_xSelf-curling fiber relatively flaky pure Ti₃C₂T_xThe mechanical property is obviously improved, wherein, MXene-L_50％Has the highest storage modulus G' and is pure Ti₃C₂T_xNearly 8 times higher. In addition, the Ti₃C₂T_xThe fibers are useful in electronic devices such as supercapacitors. The addition of L-ascorbic acid does not bring about an increase in energy density, but greatly promotes the cycle stability thereof.

Drawings

FIG. 1 is Ti₃C₂T_xA schematic diagram of a preparation method of the fiber;

FIG. 2 shows MXene-L_x％A Scanning Electron Microscope (SEM) photograph of (A) shows Ti₃C₂T_xThe shapes after treatment by adding different proportions of L-ascorbic acid (x%: 0%, 9.1%, 16.7%, 28.6%, 37.5%, 44.4%, 50.0%, 60.0%, 63.0%, 66.7%, 71.4%, representing the mass ratio of the added L-ascorbic acid);

FIG. 3 is Ti₃C₂T_xSEM photographs of the fibers (x% ═ 50.0%, 60.0%, 66.7%, 71.4%) showed changes in fiber diameter;

FIG. 4 is Ti₃C₂SEM photograph of cross section of Tx fiber;

FIG. 5 shows MXene-L in different ratios_x％A storage modulus (G') data graph (a) and an electrochemical cycling stability graph (b);

FIG. 6 shows MXene-L in different ratios_x％X-ray polycrystalline diffraction (XRD) pattern of (a);

FIG. 7 shows pure Ti₃C₂T_xWith Ti₃C₂T_xFiber MXene-L_50％X-ray photoelectron spectroscopy (XPS) C1s peak contrast plot;

FIG. 8 shows pure Ti₃C₂T_xWith Ti₃C₂T_xFiber MXene-L_50％An X-ray photoelectron spectroscopy (XPS) O1s peak comparison graph;

FIG. 9 is pure Ti₃C₂T_xWith Ti₃C₂T_xFiber MXene-L_50％Raman spectroscopy (Raman) contrast maps of;

FIG. 10 shows pure Ti₃C₂T_xWith Ti₃C₂T_xFiber MXene-L_50％Fourier infrared spectroscopy (FTIR) comparison plots;

FIG. 11 shows MXene-Lx_％Zeta Potential of (a) varies with x% and NaHCO₃Treatment of MXene-L_50％(MXene-L_50％-NaHCO₃) Zeta Potential data map of (c);

FIG. 12 shows MXene-L_50％-NaHCO₃XRD pattern (a) and SEM photograph (b);

FIG. 13 is an XRD pattern (a) of M-HCl and M-HAc, a Zeta Potential data pattern (b), an SEM photograph (c) of M-HCl and an SEM photograph (d) of M-HAc;

FIG. 14 is a chart of XPS C1s peak and O1s peak of M-HCl and M-HAc;

FIG. 15 shows c-MXene-L without sonication_50％XRD pattern (a) and SEM photograph (b) of (A).

Detailed Description

The above and further features and advantages of the present invention are described in more detail below with reference to the accompanying drawings.

Ti₃C₂T_xPreparation of MXene material: by reference, Ti disclosed in the prior art is adopted₃C₂T_xThe preparation method of the material comprises the following steps of weighing: 1, e.g. 0.5g LiF and 0.5g Ti₃AlC₂Slowly adding the mixture into 5mL of 9M HCl solution, then stirring the mixed solution at 35 ℃ in an oil bath, and after 48 hours, centrifugally washing the mixed solution with a large amount of deionized water for multiple times until the pH value is 6; then carrying out ultrasonic treatment on the obtained solution to obtain the stripped and dispersed Ti₃C₂T_xSuspending the solution; finally, carrying out high-speed centrifugal concentration on the obtained solution to obtain Ti₃C₂T_xThe solution was concentrated. The atomic force microscope result shows that the obtained Ti₃C₂T_xThe thickness of the material is mainly distributed between 1.2nm and 2.4nm, and the material corresponds to a 1-layer to 2-layer structure.

Ti₃C₂T_xPreparing fibers: adding L-ascorbic acid to Ti according to a certain mass ratio under the condition of taking argon as protective gas and ice bath₃C₂T_xIn the water solution, rigid Ti is obtained by freeze-drying after ultrasonic treatment (ultrasonic condition: power (100-) -300) W for 5-60 min)₃C₂T_xA fibrous structure formed by crimping a two-dimensional material. The flow diagram is shown in fig. 1.

At Ti₃C₂T_xDuring the self-crimping process to form fibers, the amount of L-ascorbic acid is found to be critical to the formation and morphology of the fibers. As shown in FIG. 2, Ti increased with L-ascorbic acid but was still below 50%₃C₂T_xOnly bending and folding occurs; when the L-ascorbic acid content is equal to 50%, a fibrous structure is obtained; continued increases in L-ascorbic acid resulted in a concomitant increase in fiber diameter. The change in diameter of the fibers is shown in figure 3. The resulting fiber structure is compact with a fiber cross-section as shown in fig. 4.

Ti₃C₂T_xSelf-curling fiber relatively flaky pure Ti₃C₂T_xThe mechanical properties are significantly improved, as shown in FIG. 5a, Ti₃C₂T_xFiber MXene-L_50％Has the highest storage modulus G' and is pure Ti₃C₂T_xAbout 8 times G' in two-dimensional morphology. Ti₃C₂T_xThe electrochemical properties of the fibers are shown in FIG. 5b, after addition of L-ascorbic acid, Ti₃C₂T_xThe initial energy density of the fiber is not as high as that of pure Ti₃C₂T_xBut the cycling stability is greatly improved.

From MXene-L_x％It can be seen from the XRD pattern of (FIG. 6) that Ti content increases with L-ascorbic acid content₃C₂T_xGradually moving to the left of the (002) characteristic peak of (A), the (002) interlayer spacing gradually increases, indicating that the intercalation of L-ascorbic acid is gradually carried out with the increase of the amount of L-ascorbic acid. When x% is 50%, the interlayer spacing reaches a maximum of 1.98 nm; the subsequent L-ascorbic acid content continues to increase, and the interlayer spacing does not increase any more, which indicates that the interlayer spacing expansion of the L-ascorbic acid intercalation reaches saturation.

After L-ascorbic acid intercalation, the alkene-like diol structure (HO-C ═ C-OH) is bonded with Ti through coordination bond C-O-Ti₃C₂T_xThe outer titanium atoms of (2) are bonded. The presence of this coordination bond was directly and indirectly demonstrated by the characterization results of XPS spectroscopy (fig. 7, fig. 8), Raman spectroscopy (fig. 9) and FTIR spectroscopy (fig. 10), respectively. For pure Ti₃C₂T_xAnd Ti₃C₂T_xXPS characterization of fibers C1s and O1s spectra were compared for peak separation as shown in FIG. 7, in C1s, to pure Ti₃C₂T_xCompared with MXene-L_50％New partial peaks appear at 286.95eV, 288.68eV and 291.93eV, respectively: wherein the new peak at 288.68eV corresponds to the functional group O-C ═ O in L-ascorbic acid; the new peak at 291.93ev is assigned as a C-F bond and should be due to the carbon atom of L-ascorbic acid or Ti₃C₂T_xSp appears in the preparation process²Carbon atom and Ti₃C₂T_xA combination of the F atoms; and at 286.9evThe peak is the coordination bond C-O-Ti formed by the alkene-like diol structure and the titanium. In addition, MXene-L was found from the peak separation results shown in Table 1_50％The peak positions of C-Ti and C-Ti-O in the compound are shifted to low binding energy, which is probably transferred to Ti with L-ascorbic acid₃C₂T_xThe transfer of electrons. The O1s peak separation (FIG. 8) also further demonstrates the presence of C-O-Ti (531.5 eV). Raman spectrum is shown in FIG. 9, relative to Ti₃C₂T_x，MXene-L_50％A in (1)_1gThe characteristic peak is red-shifted due to L-ascorbic acid and Ti₃C₂T_xThe surface titanium atoms combine to form C-O-Ti as a result of the charge transfer complex. FTIR spectra are shown in FIG. 10, and pure Ti₃C₂T_xCompared with MXene-L after the introduction of L-ascorbic acid_50％At 1114cm^-1And 1143cm^-1A new characteristic peak appears at the position, and the characteristic peak of the L-ascorbic acid is 1112cm^-1And 1140cm^-1MXene-L, a comparison of the two_50％The peak positions in (1) are slightly shifted, also illustrating the formation of C-O-Ti bonds.

In addition, in the FTIR spectrum (FIG. 10), L-ascorbic acid was present at 3500cm^-1Peak of (2) in addition of Ti₃C₂T_xThe latter change was broad, demonstrating that L-ascorbic acid forms a large number of intermolecular hydrogen bonds.

According to MXene-L_x％The Zeta Potential graph (FIG. 11a) shows that the Zeta Potential is increased from-39 mV of the original MXene to about-30 mV after the addition of L-ascorbic acid. When Zeta Potential is-39 mV, the electronegativity provided by the Zeta Potential is such that Ti₃C₂T_xAnd enough electrostatic repulsive force exists between adjacent nano sheets, so that a stable dispersion solution can be formed. After ascorbic acid is added, electrostatic repulsion is reduced, stability is reduced, and the product is Ti₃C₂T_xThe self-curling of the sheet provides the possibility. For further study, we used NaHCO₃For MXene-L_50％The solution was subjected to Zeta Potential adjustment. MXene-L_50％The initial pH of the solution was 3.4 when a small amount of NaHCO was added₃Then, the Zeta Potential of the solution changed significantly to-3 when the pH was 4Around 9mV (FIG. 11 b). As shown in FIG. 12a, MXene-L_50％The fiber structure of (A) is opened, i.e. a small amount of NaHCO is added₃Then, Ti₃C₂T_xThe fibers return to sheet form. In addition, the interlayer spacing was also reduced from 1.98nm to 1.76nm (FIG. 12b), and this experiment demonstrated that Zeta Potential (and L-ascorbic acid intercalation) was responsible for Ti₃C₂T_xIt is important whether the sheet can undergo self-curling.

Respectively using hydrochloric acid and acetic acid to Ti₃C₂T_xTreatment was carried out with HCl only to change the pH, no intercalation (XRD, FIG. 13a), no change of Zeta Potential (FIG. 13b), Ti₃C₂T_xNo curling occurred (SEM, fig. 13 c); i.e. changing only the pH does not cause Ti₃C₂T_xSelf-curling occurs. After treatment with HAc, no intercalation occurred (XRD, fig. 13a), only Zeta Potential was changed (fig. 13b), and no curling occurred (SEM, fig. 13 d); that is, adjusting Zeta Potential is not enough to make Ti₃C₂T_xSelf-curling occurs; and XPS results also confirmed (FIG. 14), hydrochloric acid and acetic acid treated Ti₃C₂T_xNo C-O-Ti bond appears.

In a mass ratio of 50% in Ti₃C₂T_xAdding L-ascorbic acid, directly freezing and drying without ultrasonic treatment, and recording the obtained sample as c-MXene-L_50％. As shown in FIG. 15, although c-MXene-L_50％The interlayer spacing of (A) is enlarged to about 1.98nm, namely intercalation occurs, but Ti₃C₂T_xOnly a small amount of curling appeared, demonstrating the ultrasound versus rigid Ti₃C₂T_xThe self-curling of the sheet has an important role, presumably ultrasound can be in Ti₃C₂T_xThe structure of (2) introduces defects to promote the occurrence of self-curling.

In conclusion: 1. the L-ascorbic acid can successfully induce Ti₃C₂T_xSelf-curling; 2. the success of L-ascorbic acid in inducing self-curling benefits from its ability to intercalate Ti₃C₂T_xInterlaminar formation of with Ti₃C₂T_xC-O-Ti bonds are formed on the surface to form local crystal junctionsThe structure is slightly deformed, and meanwhile, a plurality of large aggregates are formed among L-ascorbic acid molecules among layers through hydrogen bond combination, so that local deformation can be orderly arranged and extended and accumulated, and Ti finally occurs under the ultrasonic and freeze-drying conditions due to the weakening of electrostatic repulsive force between the lamellar layers₃C₂T_xAnd a dense fiber structure is obtained.

The foregoing is merely a preferred embodiment of the invention, which is intended to be illustrative and not limiting. It will be understood by those skilled in the art that various changes, modifications and equivalents may be made therein without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. Two-dimensional Ti₃C₂T_xThe preparation method of the self-crimping fiber of the material is characterized by comprising the following steps: mixing Ti₃C₂Dispersing the material T in water, adding L-ascorbic acid, performing ultrasonic treatment under the condition of argon as protective gas and ice bath, and freeze-drying to obtain Ti₃C₂T_xFiber MXene-L_x％Wherein x% is the mass ratio of the L-ascorbic acid.

2. A two-dimensional Ti according to claim 1₃C₂T_xThe preparation method of the self-crimping fiber of the material is characterized in that x% is more than or equal to 50%.

3. A two-dimensional Ti according to claim 1₃C₂T_xThe preparation method of the self-crimping fiber of the material is characterized in that ultrasound and freeze-drying are matched, wherein the ultrasound power is 100-300W, and the ultrasound time is 5-60 min.

4. A two-dimensional Ti according to claim 1₃C₂T_xMethod for preparing self-crimping fibers of a material, said Ti₃C₂T_xMaterialThe thickness of the film is less than or equal to 3 nm.

5. A two-dimensional Ti according to claim 1₃C₂T_xMethod for preparing self-crimping fibers of a material, said Ti₃C₂T Material by mixing LiF and HCl to Ti₃AlC₂And etching to obtain the product.

6. Two-dimensional Ti prepared by the preparation method of any one of claims 1 to 5₃C₂T_xSelf-crimping fibers of a material.

7. A two-dimensional Ti as defined in claim 6₃C₂T_xUse of self-crimping fibres of a material in a supercapacitor.