Preparation method of MXene-metal organic framework composite material and flexible functional device

Abstract

The invention discloses a preparation method of an MXene-metal organic framework composite material and a flexible functional device, Ti3C2Tx-coated Cu3 (HHTP) 2 is added into ultrapure water to prepare a Ti3C2Tx-coated Cu3 (HHTP) 2 dispersion liquid with a certain concentration, a pretreated textile fabric is placed in the Ti3C2Tx-coated Cu3 (HHTP) 2 dispersion liquid for a certain time, the textile fabric is taken out and dried, and the Ti3C2Tx-coated Cu3 (HHTP) 2 flexible functional material is obtained. The preparation method comprises the following steps: preparing Ti < 3 > C < 2 > T < x > (at) Cu < 3 > (HHTP) 2 from Cu (CO < 2 > CH < 3 >) < 2 >. H2O and HHTP by adopting a hydrothermal method; the Ti < 3 > C < 2 > T < x > (at) Cu < 3 > (HHTP) < 2 > flexible functional material is used as a stress strain sensor, the maximum resistance change rate reaches 60%, and high stress sensitivity is presented; the bending response has a linear change rate of 6%, and the sensing performance is basically not attenuated after 100 cycles.

Description

Technical Field

[0001] The present invention relates to a method for preparing a MXene-metal organic framework composite material and a flexible functional device, belonging to the technical field of preparing MXene-metal organic framework composite materials. Background Art

[0002] In recent years, with the increasing popularity of smart wearable devices and the growing demand for health monitoring, the application prospects of flexible wearable sensors have become increasingly broad in multiple fields. These sensors can be integrated into devices such as clothing, insoles, and skin patches to enable real-time monitoring of human health data such as heart rate, respiration, body temperature, blood sugar, and blood pressure, thereby providing individuals with precise health management and early warning services. Furthermore, flexible sensors are widely used in fields such as sports monitoring, environmental monitoring, artificial intelligence, and the Internet of Things, demonstrating their importance in future technologies. However, despite the significant advantages of flexible sensors, improving their performance still faces numerous challenges, particularly in terms of sensitivity, stability, response speed, and durability. These issues have limited their widespread adoption in practical applications.

[0003] To overcome the limitations of traditional flexible sensors, researchers have begun exploring novel materials. MXene, due to its exceptional performance, has become a hot topic in flexible sensor research. As an emerging two-dimensional nanomaterial, MXene has a layered crystal structure similar to graphene, but exhibits significant differences in chemical composition and surface modification properties.

[0004] MXene materials, a novel class of two-dimensional transition metal carbides, nitrides, or carbonitrides, have rapidly become a research hotspot in materials science since their discovery in 2011. These materials have attracted considerable attention due to their unique layered structure, excellent electrical conductivity, good mechanical properties, and diverse surface chemistry. The discovery of MXene stems from research on MAX phase materials. By selectively etching the A-layer elements within the MAX phase, MXene has been successfully fabricated into two-dimensional materials with graphene-like structures.

[0005] The emergence of MXene materials has enriched the family of two-dimensional materials and provided new avenues for the exploration of novel nanomaterials. Furthermore, MXene's unique structure and properties offer enormous potential for applications in energy storage, catalysis, electromagnetic shielding, sensors, and other fields. Furthermore, MXene's tunable surface chemistry offers broad scope for material functionalization. With increasing research, MXene is showing promising application prospects in a wide range of fields, including electromagnetic interference (EMI) shielding, separation membranes, energy storage and collection, and electronics.

[0006] MXenes(M n+1 X n Tx ) is mainly prepared by selectively etching the "A" layer in the MAX phase precursor, where M represents an early transition metal element (such as Ti, V, etc.), A is a group IIIA or IVA element (such as Al, Si, etc.), X represents carbon or nitrogen, and T x It is worth noting that the surface functional groups (T x From the microstructural point of view, the single-layer MXene obtained by etching and ultrasonic peeling presents a unique "sandwich" layered structure: Ti3C2T x For example, it is composed of three layers of Ti atoms sandwiched between two layers of C atoms in a periodic arrangement, and the surface functional groups are bonded to the outermost Ti atoms.

[0007] Flexible stress and strain sensors are widely used in fields such as health monitoring, human-computer interaction, and intelligent robotics. In recent years, research has focused on improving sensitivity, response range, stability, and durability. Combining conductive materials (such as carbon-based materials, conductive polymers, and liquid metals) with microstructure designs (such as cracks, wrinkles, and porous structures) has significantly improved sensor performance.

[0008] How to use the MXene-metal organic framework composite material preparation method to prepare a functional composite material that can be applied to the field of stress and strain sensor technology and has high sensitivity has become a problem to be solved. Summary of the Invention

[0009] The purpose of the present invention is to provide a method for preparing a MXene-metal organic framework composite material and a functional device with high stress and bending sensitivity.

[0010] In order to solve the above-mentioned technical problems, the purpose of the present invention is achieved as follows:

[0011] The preparation method of the MXene-metal organic framework composite material involved in the present invention comprises the following steps: x @Cu3(HHTP)2 is added to ultrapure water to prepare a certain concentration of Ti3C2T x @Cu3(HHTP)2 dispersion, the pretreated textile fabric was placed on Ti3C2T x @Cu3(HHTP)2 dispersion for a certain time, take it out and dry it to obtain Ti3C2T x @Cu3(HHTP)2 flexible functional material.

[0012] On the basis of the above scheme and as a preferred scheme of the above scheme: the pretreatment of the textile fabric refers to placing the textile fabric in an alkaline solution, heating and boiling, taking it out, washing and drying it, then washing the textile fabric in an ethanol solution, taking it out and drying it again; then placing the textile fabric in a HACC solution for a certain period of time, then rinsing it, taking it out and vacuum drying it.

[0013] On the basis of the above scheme and as a preferred scheme of the above scheme: the Ti3C2T x The preparation process of @Cu3(HHTP)2 is as follows:

[0014] Few-layer Ti3C2T x Evenly dispersed in deionized water, a few-layer Ti3C2T x Solution, Cu(CO2CH3)2·H2O and 0.0357 g HHTP were dissolved in deionized water and ethanol solution, respectively, to obtain Cu(CO2CH3)2·H2O solution and HHTP solution;

[0015] Few-layer Ti3C2T x The solution and the HHTP solution were mixed and ultrasonically dispersed to form a mixed solution; Cu(CO2CH3)2·H2O solution was added dropwise to the mixed solution under ultrasonic conditions and ultrasonically dispersed, and then the reaction solution was placed in a water bath and reacted under stirring conditions, and then the suspension was centrifuged and washed with ethanol / deionized water solution and then with deionized water to remove residual H3BTC and copper acetate; the product after centrifugation was vacuum dried to obtain Ti3C2T x @Cu3(HHTP)2.

[0016] On the basis of the above scheme and as a preferred scheme of the above scheme: the few-layer Ti3C2T x The preparation process is as follows:

[0017] Dissolve LiF in hydrochloric acid and stir to fully dissolve it to obtain a LiF solution;

[0018] The LiF solution is poured into a polytetrafluoroethylene reactor, which is placed in a water bath and heated to a set temperature. Then, Ti3AlC2 is added to the reactor and stirred at the set temperature to obtain a reaction solution. The reaction solution is poured into a centrifuge tube, washed with dilute hydrochloric acid to remove excess LiF, and then washed with deionized water and centrifuged until the pH of the solution is greater than or equal to 6. The precipitate is collected and dissolved in deionized water to obtain Ti3C2T x solution;

[0019] Under nitrogen protection, Ti3C2T x The solution was ultrasonicated in an ultrasonic disperser, and then Ti3C2T xThe solution was centrifuged and the upper liquid was collected. It was freeze-dried in vacuum to obtain a few-layer Ti3C2T x .

[0020] On the basis of the above scheme and as a preferred scheme of the above scheme: the Ti3C2T x The mass ratio of Cu(CO2CH3)2·H2O is 1:0.25-1.

[0021] The present invention also relates to a flexible functional device for use in stress and strain sensors, comprising Ti3C2T prepared by the above preparation method. x @Cu3(HHTP)2 flexible functional material.

[0022] The beneficial effects of the present invention are as follows: the preparation method of the MXene-metal organic framework composite material and the functional device involved in the present invention adopt a hydrothermal method to prepare Ti3C2T x @Cu3(HHTP)2. Ti3C2T x The maximum resistance change rate of the @Cu3(HHTP)2 flexible functional material stress and strain sensor reaches 60%, showing high stress sensitivity; the bending response has a linear change rate of 6%, and the long-term stability measurement of the resistance change rate after 100 uses shows almost no attenuation. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a few-layer Ti3C2T x TEM images, SEM images and EDS element distribution maps;

[0024] Figure 2 It is a few-layer Ti3C2T x IR spectrum and XRD spectrum of

[0025] Figure 3 It is a few-layer Ti3C2T x XPS spectrum of

[0026] Figure 4 The Ti3C2T prepared in Example 3 x Transmission electron microscopy (TEM) images, scanning electron microscopy (SEM) images, and EDS elemental distribution maps of @Cu3(HHTP)2;

[0027] Figure 5 The Ti3C2T prepared in Example 3 x @Infrared spectra and XRD spectra of Cu3(HHTP)2 and Cu3(HHTP)2 prepared in Comparative Example 1;

[0028] Figure 6 The Ti3C2T prepared in Example 3 xXPS spectra of Cu3(HHTP)2 and Cu3(HHTP)2 prepared in Comparative Example 1;

[0029] Figure 7 are graphs showing the change in relative resistance rate versus stress and the change in relative resistance rate versus bending angle for CHT-0, T(Cu-HHTP)-1, T(Cu-HHTP)-2, T(Cu-HHTP)-3, and T(Cu-HHTP)-4;

[0030] Figure 8 Ti3C2T x Schematic diagram of the conductive paths of the Cu3(HHTP)2 flexible functional material in the tensile direction (L direction) and the perpendicular direction (T direction) when subjected to stress along the L direction;

[0031] Figure 9 The relationship between adsorption concentration, treatment time, adsorption times, loading amount, and resistance in Examples 11-28;

[0032] Figure 10 1 is the SEM image of the untreated cotton fabric, the comparative example 2 and the cotton fabric treated under the optimal process conditions;

[0033] Figure 11 It is the CHT (Cu-HHTP) stress and strain sensor characteristic;

[0034] Figure 12 This is a diagram showing the application of CHT (Cu-HHTP) stress and strain sensor in human motion measurement. DETAILED DESCRIPTION

[0035] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0036] The present invention relates to a method for preparing a MXene-metal organic framework composite material, wherein Ti3C2T x @Cu3(HHTP)2 is added to ultrapure water to prepare a certain concentration of Ti3C2T x @Cu3(HHTP)2 dispersion, the pretreated textile fabric was placed on Ti3C2T x @Cu3(HHTP)2 dispersion for a certain time, take it out and dry it to obtain Ti3C2T x @Cu3(HHTP)2 flexible functional material.

[0037] Few-layer Ti3C2T was prepared by lithium fluoride and hydrochloric acid etching. x The hydrothermal method was used to make Cu3(HHTP)2 on Ti3C2T x The Ti3C2T nanosheets were generated in situ. x @Cu3(HHTP)2 composite material.

[0038] Example 1

[0039] This embodiment involves a few-layer Ti3C2T x Preparation, the preparation process is as follows: slowly dissolve 3.2g LiF in 40mL of 9M / L hydrochloric acid, stir for 10min to fully dissolve it, pour the LiF solution into a polytetrafluoroethylene reactor, place it in a water bath and heat it to 40°C, then slowly add 2g Ti3AlC2 to the reactor several times, stir at 40°C for 48h, pour the reaction solution into a centrifuge tube, wash with dilute hydrochloric acid 3 to 5 times to remove excess LiF. Then wash with deionized water and centrifuge at a speed of 3500rpm / min, centrifuge for 5min each time, and centrifuge 6-8 times until the pH of the solution is greater than or equal to 6. Collect the precipitate and dissolve it in 100mL of deionized water to obtain Ti3C2T x solution, under nitrogen protection, Ti3C2T x The solution was ultrasonicated in an ultrasonic disperser for 2 h, and then Ti3C2T x The solution was centrifuged at a speed of 3500 rpm / min for 30 min, and the upper layer of liquid was collected. It was freeze-dried in a vacuum for 48 h to obtain a few-layer Ti3C2T x .

[0040] Ti3C2T x TEM transmission electron microscope images and SEM scanning electron microscope images are shown in Figure 1 (ac) and Figure 1 As shown in (d) in the figure. Figure 1 The transmission electron microscopy (TEM) image shown in (a) confirms that the exfoliated Ti3C2T x The sheet is ultra-thin and transparent. There is a wrinkle structure on the surface of the sheet, which is the result of Ti3C2T x The flexibility of the nanosheets. Figure 1 In (b) and (c), the prepared Ti3C2T x The number of layers shows that it is a stack of two to three layers, which can be called a few-layer Ti3C2T x , after ultrasonication, Ti3C2T x The ability to separate into such a thin film structure indicates that the etching of MAX was successful, the aluminum layer was successfully removed, and a single layer or a few layers of the binary nanomaterial Ti3C2T was prepared. x . Figure 1 (d) shows a few-layer Ti3C2T x The morphological features of the multilayer Ti3C2T xThe formation of a sheet structure indicates that the peeling process has been basically completed. Figure 1 In (e), it can be seen that the prepared Ti3C2T x The carbon content is the highest among all elements, accounting for 71.53%. The Ti content is 28.47%, which is consistent with Ti3C2T x chemical composition.

[0041] right Figure 2 Ti3C2T shown in (a) and (b) x The infrared spectroscopy (FTIR) and X-ray diffraction (XRD) spectrum analysis showed that the material has a typical few-layer structure and surface chemical properties. In the infrared spectrum, the broad peak near 3450cm-1 corresponds to the OH stretching vibration, indicating the presence of hydroxyl groups on the surface or between layers of the material; the absorption peak at 1630cm-1 corresponds to the C=O stretching vibration, indicating the presence of carboxylic acid or carbonyl functional groups on the surface of the material. No significant CF bond vibration peak was observed near 1200cm-1, indicating that there are few fluorine terminals remaining after etching, and the surface functional groups are mainly oxygen and hydroxyl groups. This chemical property makes it highly hydrophilic and suitable for electrochemical or catalytic applications. In addition, the weak peak in the range of 600–400cm-1 is related to the skeleton vibration of Ti-O or Ti-C, reflecting the Ti3C2T x integrity of the crystal structure.

[0042] Ti3C2T x The core feature of the XRD spectrum is the (002) crystal plane peak, which is located at about 6°–7° 2θ (Cu Kα radiation), and the corresponding interlayer spacing is Significantly higher than multilayer Ti3C2T x Typical values (approx. ), indicating that the sample is a few-layer structure with ions inserted between the layers. The significant broadening of the (002) peak further supports the reduction of the number of layers and the disorder of stacking, which is consistent with the few-layer Ti3C2T x The typical characteristics of the MAX phase (Ti3AlC2) are not found in the spectrum at about 39°2θ, indicating that the etching process is thorough. At the same time, the characteristic peak of TiO2 at about 26°2θ is not detected, indicating that the material has not undergone significant oxidation during the preparation process and has good structural stability. In summary, the XRD results are consistent with the infrared spectroscopy analysis, which jointly verify the few-layer Ti3C2T x Successful preparation.

[0043] To gain a deeper understanding of Ti3C2T x We conducted X-ray photoelectron spectroscopy (XPS) analysis on the surface chemical characteristics of Figure 3 shown. Figure 3The full spectrum in (a) shows obvious signals of Ti, C, O, and F. Specifically, the peaks with binding energies of 284, 453, and 476 are attributed to the characteristic signals of C1s, Ti 2p, and O1s, respectively. Figure 3 (b) is the C1s spectrum, Ti3C2T x The C1s high-resolution spectrum of the powder shows three main peaks at 281.38eV, 284.60eV and 287.76eV, corresponding to the Ti–C bond, C–C bond and C–O bond. Among them, the Ti–C bond is represented by Ti3C2T x The bonding between Ti and C within the layer; the presence of C–O bonds indicates that partial oxidation has occurred on the material surface. Figure 3 (c) is the O1s spectrum. The peak at ~530eV in the O 1s spectrum further confirms the presence of Ti(IV) oxide, and the peak at ~532eV shows the O–H / O x groups (~532 eV), indicating that hydroxyl or oxygen-containing functional groups are bound to the surface. Figure 3 (c) is the Ti 2p spectrum. The peaks of the Ti 2p high-resolution spectrum can be deconvoluted into Ti–C, Ti(II), Ti(III), Ti(IV) and Ti–F. The oxidation state T originates from the formation of surface mixed oxides or carbon oxides, indicating that Ti3C2T x The surface termination is not a single chemical state. In summary, XPS analysis reveals that Ti3C2T x The chemical composition and functional groups of the surface highlight the diversity and complexity of its surface chemistry, providing a key basis for subsequent performance regulation.

[0044] Examples 2-5

[0045] Examples 2-5 involve Ti3C2T x @Cu3(HHTP)2 preparation, the specific preparation process is as follows: 0.03g of few-layer Ti3C2T x Evenly dispersed in 10 ml of deionized water, a few-layer Ti3C2T x Solution, 0.03g Cu(CO2CH3)2·H2O and 0.0357g HHTP (2,3,6,7,10,11-hexahydroxytriphenyl) were dissolved in 10ml deionized water solution and 10ml ethanol solution respectively. xThe solution and HHTP solution were mixed in a 60ml glass bottle and ultrasonically dispersed for 30min, which was uniformly dispersed in the mixed solution. After that, the Cu(CO2CH3)2·H2O solution was added dropwise to the mixed solution under ultrasonic conditions and ultrasonically dispersed for 15min. The reaction solution was then placed in a magnetic stirring water bath at a water temperature of 80°C and reacted for 12h under magnetic stirring conditions. The suspension was then centrifuged at 3000rpm / min for 5min and washed 3 times with ethanol / deionized water (1:2v / v) solution and 3 times with deionized water to remove residual H3BTC and copper acetate. The centrifuged product was then dried under vacuum at 80°C for 12h to obtain Ti3C2T x @Cu3(HHTP)2.

[0046] Changing Ti3C2T x Under the conditions of the mass ratio of Ti3C2T to Cu(CO2CH3)2·H2O, x The mass ratios of Ti3C2T to Cu(CO2CH3)2·H2O are 1:0.25, 1:0.5, 1:0.75 and 1:1 respectively. x @Cu3(HHTP)2 composite material.

[0047] Comparative Example 1

[0048] This comparative example involves the preparation process of Cu3(HHTP)2, and the specific process is as follows: 0.03g of few-layer Ti3C2T x Evenly dispersed in 10 ml of deionized water, a few-layer Ti3C2T x To prepare a solution, 0.03g of Cu(CO₂CH₃)₂·H₂O and 0.0357g of HHTP (2,3,6,7,10,11-hexahydroxytriphenyl) were dissolved in 10ml of deionized water and 10ml of ethanol, respectively. The HHTP solutions were first mixed in a 60ml glass bottle and ultrasonically dispersed for 30 minutes until uniformly dispersed throughout the mixture. Subsequently, the Cu(CO₂CH₃)₂·H₂O solution was added dropwise to the mixture under ultrasonic conditions and ultrasonically dispersed for 15 minutes. The reaction solution was then placed in a magnetically stirred water bath at 80°C for 12 hours. The suspension was then centrifuged at 3000 rpm / min for 5 minutes and washed three times with ethanol / deionized water (1:2 v / v) and three times with deionized water to remove residual H₃BTC and copper acetate. The centrifuged product was then dried under vacuum at 80°C for 12 hours to yield Cu₃(HHTP)₂.

[0049] Figure 4 Ti3C2T xMulti-scale morphological characteristics and elemental composition analysis results of @Cu3(HHTP)2 composite materials. Figure 4 (a), (b) and (c) are transmission electron microscope (TEM) images at different magnifications, which clearly show the microstructural characteristics of the material: the low-magnification TEM image shows that the composite material has a uniform lamellar structure, Ti3C2T x Cu3(HHTP)2 nanoparticles were successfully loaded on the substrate; high-magnification TEM images further revealed the lattice fringes of Cu3(HHTP)2 and Ti3C2T x The close combination of the layered structures confirms that the two form a stable heterostructure. Figure 4 (d) shows a scanning electron microscope (SEM) image, which shows the overall morphology of the material at the mesoscopic scale. The overall surface is no longer as smooth as that of pure Ti3C2T x The reason why it is so smooth is that the introduction of Cu3(HHTP)2 changes the overall microstructure. Figure 4 (e) shows the EDS element analysis, which shows the presence of characteristic elements such as Ti, C, O, and Cu in the material. The uniform distribution of Cu element confirms the successful synthesis of Cu3(HHTP)2, while the high intensity signal of Ti element reflects the successful synthesis of Ti3C2T x Taken together, these characterization results preliminarily verify the dominant role of Ti3C2T x Successful preparation of @Cu3(HHTP)2 composite material.

[0050] like Figure 5 In (a), the structural evolution was further analyzed using Fourier transform infrared spectroscopy. The Cu3(HHTP)2 particles have the highest peaks at 1215, 1305, and 1445 cm -1 There are three sharp vibration peaks at the bottom, which are attributed to CO, C=O and CH respectively. These characteristic peaks are retained in the composite material, confirming that Cu3(HHTP)2 particles and Ti3C2T x Successful combination. Figure 5 (b) The Cu3(HHTP)2 particles and Ti3C2T were studied by X-ray diffraction (XRD) analysis. x @Cu3(HHTP)2 composite material crystal structure. Consistent with the results of high-resolution transmission electron microscopy, Cu3(HHTP)2 particles show characteristic diffraction peaks at (200), (210) and (004), further indicating its two-dimensional hexagonal crystal structure. In the composite system, Ti3C2T x The coexistence of the characteristic diffraction peaks of Cu3(HHTP)2 proves that the self-assembly of Cu3(HHTP)2 particles does not destroy the Ti3C2T x It is worth noting that the Ti3C2T xThe (002) diffraction peak of Ti3C2T is slightly shifted to 2θ=5.5°, which is consistent with the Ti3C2T x The lattice expansion of the interlayer spacing is related to the

[0051] like Figure 6 X-ray photoelectron spectroscopy (XPS) was used to characterize the Cu3(HHTP)2 and Ti3C2T x @Cu3(HHTP)2 was characterized by Cu 2p, O 1s and C1s peaks in the range of 0-1200eV. Figure 6 (a) is the full spectrum, showing Ti3C2T x The characteristic peak of Ti 2p also appeared in the spectrum of @Cu3(HHTP)2, which indicates that the material contains Ti3C2T x . Figure 6 (b) shows Cu3(HHTP)2 and Ti3C2T x @C1s spectrum of Cu3(HHTP)2: The peaks of Cu3(HHTP)2 at 284.7eV and 288.2eV correspond to C=C and O=CO respectively; while Ti3C2T x A new peak appeared at 281.3 eV for @Cu3(HHTP)2, which was attributed to the C-Ti bond. Figure 6 (c) shows the O1s spectrum, where Ti3C2T x @Cu3(HHTP)2 corresponds to lattice oxygen (O1), oxygen defect (O2) and surface adsorbed oxygen (O3) at 529.35eV, 531.3eV and 532.8eV, respectively. The appearance of lattice oxygen (O1) may be due to the Ti3C2T x The Cu on the surface combines with O to form lattice oxygen, which is absent in pure Cu3(HHTP)2, further confirming that Ti3C2T x Successful synthesis of @Cu3(HHTP)2 material. Figure 6 (d) shows the Cu 2p spectrum. The peak at 934.8 eV indicates that the Cu in Cu3(HHTP)2 is mainly Cu 2+ The satellite peak near 943eV further confirms the existence of Cu 2+ The existence of Ti3C2T x A new peak appeared at 934.8eV in Cu3(HHTP)2, confirming that some Cu 2+ Ti3C2T x The surface functional groups are reduced to Cu + The slight shift of Cu 2p peak in the composite compared with pure Cu3(HHTP)2 may be due to the xElectronic interaction between Cu3(HHTP)2.

[0052] Ti3C2T was prepared by hydrothermal method. x @Cu3(HHTP)2 composite material. TEM and SEM showed that the composite material had a uniform lamellar structure, Ti3C2T x Cu3(HHTP)2 nanoparticles were successfully loaded on the substrate. Infrared and XRD images showed that the characteristic peaks and crystal structure of Cu3(HHTP)2 were retained in the composite material, confirming that Cu3(HHTP)2 particles and Ti3C2T x Successfully combined. In XPS test, Ti3C2T x The appearance of lattice oxygen (O1) in @Cu3(HHTP)2 proves that Ti3C2T x The Cu on the surface combines with O to form lattice oxygen, which is absent in pure Cu3(HHTP)2, further confirming that Ti3C2T x Successful synthesis of @Cu3(HHTP)2 material.

[0053] Examples 6-10

[0054] The preparation method of the MXene-metal organic framework composite material involved in Examples 6-10 includes the pretreatment of textile fabrics and the Ti3C2T x Preparation of @Cu3(HHTP)2 flexible functional materials.

[0055] Pretreatment of textile fabrics: Prepare a 20g / L caustic soda solution at a bath ratio of 1:30. Place pre-cut fabric swatches (5 x 8cm) in a solution heated to 100°C and boil for 1 hour. Wash with warm and then cold water, then dry. The cotton fabric is then thoroughly washed in a 20% by volume ethanol solution and dried at 80°C for 2 hours. The cotton fabric is then exposed to a 1mg / mL HACC solution for 10 minutes, rinsed three times, and dried in a vacuum oven at 80°C for 2 hours.

[0056] Ti3C2T x Preparation of @Cu3(HHTP)2 flexible functional materials: Take Ti3C2T x @Cu3(HHTP)2 was added to ultrapure water to prepare Ti3C2T x @Cu3(HHTP)2 dispersion was ultrasonically dispersed for 0.5h, and the cotton fabric was treated for 20min under ultrasonic dispersion conditions, the adsorption times were one, and the fabric was dried at 80℃ for 2h. x @Cu3(HHTP)2 are Ti3C2T prepared in different proportions in Examples 2-5 x@Cu3(HHTP)2. In the preparation of Ti3C2T x @Cu3(HHTP)2, Ti3C2T x The mass ratios of Ti3C2T with Cu(CO2CH3)2·H2O are 1:0.25, 1:0.5, 1:0.75, and 1:1, respectively. x @Cu3(HHTP)2 composite material.

[0057] The fabric samples with different ratios were named T(Cu-HHTP)-1, T(Cu-HHTP)-2, T(Cu-HHTP)-3, and T(Cu-HHTP)-4.

[0058] Comparative Example 2

[0059] The preparation method of the flexible functional material involved in this comparative example is as a control sample. The difference from Example 6 is that 1 mg / mL Ti3C2T x The prepared fabric was named CHT-0.

[0060] Figure 7 (ac) in the figure show the relative resistance change rates of five materials, CHT-0, T(Cu-HHTP)-1, T(Cu-HHTP)-2, T(Cu-HHTP)-3 and T(Cu-HHTP)-4, under different stresses. In different stress tests, T(Cu-HHTP)-3 showed the highest resistance change rate. Under stress conditions of 1N, 2N and 3N, its relative resistance change rates were 30%, 32% and 34% respectively. (de) in the figure shows their responses at different bending angles. Judging from the test results, the relative resistance change of all materials is not large, and the relative resistance change rates between the materials are very close, and no material has a clear advantage. Among them, T(Cu-HHTP)-3 shows the highest resistance change rate with a slight advantage. According to Figure 7 The relative resistance change rate test results shown in the figure show that T(Cu-HHTP)-3 exhibits the best sensing performance under both stress and bending conditions.

[0061] Figure 8 Ti3C2T x Schematic diagram of the conductive path of the @Cu3(HHTP)2 flexible functional material in the tensile direction (L direction) and the perpendicular direction (T direction) when subjected to stress along the L direction. Among them, a1 represents the cross section of the fiber bundle in the unstretched state, a2 is the L-direction tensile state, and a3 is the T-direction tensile state. The red circle in the figure represents the conductive Ti3C2T adsorbed on the fiber surface. x@Cu3(HHTP)2 layer, which forms a conductive network under certain conditions. In the unstretched state (a1), Ti3C2T x @Cu3(HHTP)2 flexible functional material is evenly coated on the fiber surface to form a continuous conductive coating. The conductive network at this time presents a typical isotropic distribution feature, and the electron transmission path is randomly distributed in three-dimensional space. This structure is Ti3C2T x @Cu3(HHTP)2 flexible functional materials provide basic conductive properties. When the material is stretched along the L direction, the fiber bundles in the L direction are tightened, and the Ti3C2T x @Cu3(HHTP)2 sheet contact area increases, the conductive path increases, and the Ti3C2T x @Cu3(HHTP)2 sheets will be oriented along the stretching direction to form a highly ordered one-dimensional conductive path. This orientation significantly improves the axial conductivity of the material. x The improved conductivity of the @Cu3(HHTP)2 flexible functional material is primarily due to the following mechanisms: increased overlap between the layers reduces contact resistance; and directional alignment creates a more continuous conductive network. This property makes it particularly suitable for applications requiring directional conductivity or strain sensing, such as signal transmission lines in wearable devices. In contrast, the T-direction fiber bundles remain virtually unchanged, resulting in minimal resistance change.

[0062] It is worth noting that the introduction of Cu3(HHTP)2 has a significant impact on the material properties. As a metal organic framework material, Cu3(HHTP)2 can not only improve the x @Cu3(HHTP)2 can also provide additional conductive paths by interfacial bonding with the fiber substrate. More importantly, its porous structure can buffer mechanical stress and reduce the x @Cu3(HHTP)2 flakes during cyclic deformation, thereby significantly improving the durability of the material.

[0063] Examples 11-16

[0064] Preparation method of MXene-metal organic framework composite materials involved in Examples 11-16: According to the Ti3C2T x @Cu3(HHTP)2 was added to ultrapure water to prepare Ti3C2T with different concentrations x @Cu3(HHTP)2 dispersion was ultrasonically dispersed for 0.5h. Cotton fabric was treated under ultrasonic dispersion conditions for 20min, adsorbed once, and dried at 80℃ for 2h. Ti3C2T x@Cu3(BTC)2 were added at concentrations of 1 mg / mL, 2 mg / mL, 3 mg / mL, 4 mg / mL, 5 mg / mL, and 6 mg / mL, respectively.

[0065] Examples 17-22

[0066] The preparation method of the flexible functional material based on in-situ modified nanosheets involved in Examples 17-22: According to the Ti3C2T x @Cu3(HHTP)2 was added to ultrapure water to prepare 5 mg / mL Ti3C2T x The Cu3(HHTP)2 dispersion was ultrasonically dispersed for 0.5 h. The cotton fabric was treated with ultrasonic dispersion for 20, 40, 60, 80, 100, and 120 min, with one adsorption cycle, and then dried at 80°C for 2 h.

[0067] Examples 23-28

[0068] The preparation method of the flexible functional material based on in-situ modified nanosheets involved in Examples 23-28: According to the Ti3C2T x @Cu3(HHTP)2 was added to ultrapure water to prepare 5 mg / mL Ti3C2T x The Cu3(HHTP)2 dispersion was ultrasonically dispersed for 0.5 h. Cotton fabric was treated with ultrasonic dispersion for 20 min, with the number of times being 1, 2, 3, 4, 5, and 6, respectively, and then dried at 80°C for 2 h.

[0069] Figure 9 The Ti3C2T x @Cu3(HHTP)2 loading behavior on cotton fabric and its effect on electrical resistance. Figure 9 (a) shows that as Ti3C2T x @Cu3(HHTP)2 concentration increases, and the amount is also gradually increasing. After the cotton fabric is pretreated with HACC, its surface is rich in -NH3 + functional groups, with negatively charged Ti3C2T x @Cu3(HHTP)2 attract each other through electrostatic attraction, making Ti3C2T x @Cu3(HHTP)2 can be easily fixed on its surface. According to the trend of resistance gradually decreasing with increasing concentration, considering the Ti3C2T x @Cu3(HHTP)2 preparation time, usage concentration and other conditions were selected with a concentration of 4 mg / ml for subsequent experiments. Figure 9 (b) in the figure calculated the Ti3C2Tx The load-bearing capacity of the CHT (Cu-HHTP) flexible functional material after treatment with a Cu3(HHTP)2 dispersion for 20, 40, 60, 80, 100, and 120 minutes. The figure shows that the load reaches a plateau after 20 minutes, and the resistance also varies within a certain range. Considering various factors, 20 minutes was selected as the adsorption time for the process. Figure 9 (c) in the figure calculated the effect of 5mg / ml Ti3C2T x The load-bearing capacity of CHT (Cu-HHTP) flexible functional materials treated with a Cu₃(HHTP)₂ dispersion 1, 2, 3, 4, 5, and 6 times was determined. The load-bearing curve shows that the adsorption plateau is reached after 3 adsorption cycles, and the resistance also reaches a turning point. Therefore, 3 adsorption cycles were selected as the experimental process. The optimal process was selected to be an adsorption concentration of 5 mg / ml, a treatment time of 20 minutes, and 3 adsorption cycles. The fabric sample obtained from this optimal process was named CHT (Cu-HHTP).

[0070] Figure 10 Scanning electron microscope (SEM) images of cotton fabric and cotton fabrics treated with different materials are displayed. By comparing them, the changes in the surface morphology of the materials and the effects of their treatment can be intuitively observed. Figure 10 (a) shows an SEM image of pristine cotton fabric, showing a smooth fiber surface and uniform structure, exhibiting typical morphological characteristics of natural cellulose fibers. This smooth surface may limit its functional applications, so subsequent treatment is needed to improve its properties. Figure 10 (b) is the Ti3C2T x The treated cotton fabric showed obvious nanosheet structure on its fiber surface, indicating that Ti3C2T x The material successfully adhered to the fiber surface. This modification increases the roughness of the fiber surface, which may significantly improve the conductivity, adsorption capacity or other functional properties of cotton fabrics. Figure 10 (c) is the Ti3C2T under the best process conditions x @Cu3(HHTP)2 treated cotton fabric morphology. Cu3(HHTP)2 is a metal organic framework that is x The surface properties of the fiber are further changed after compounding. Cu3(HHTP)2 particles are dispersed in the Ti3C2T x The Ti3C2T layer is almost completely covered by the dot-shaped protrusions and the particle size is more uniform. x layer, forming a dense nanoparticle stacking structure. Comprehensive analysis shows that the processing process has achieved the goal of x Modified to Ti3C2T xGradient evolution of composite functionalization of @Cu3(HHTP)2. Ti3C2T x As an intermediate layer, it not only maintains its inherent conductivity but also provides anchoring sites for the growth of Cu3(HHTP)2. The introduction of Cu3(HHTP)2 further optimizes the surface chemistry. Furthermore, none of the treatments caused fiber breakage or structural collapse, indicating that this method has minimal impact on the mechanical integrity of the cotton fabric.

[0071] CHT (Cu-HHTP) is used as a flexible functional device for stress and strain sensors. Figure 11 The response of CHT (Cu-HHTP) sensor to stress and bending angle is demonstrated. Figure 11 Figure (a) shows the relationship between the relative resistance change rate of the CHT (Cu-HHTP) sensor and different stresses. As can be seen from the figure, the relative resistance change rate is 40%, 45%, and 50% under stresses of 1N, 2N, and 3N, respectively. This shows that the sensor has high sensitivity over a wide stress range and can effectively capture stress changes. Figure 11 Figure (b) shows the sensor's performance under bending angle. The relative resistance changes are 2%, 4%, and 6% at bending angles of 30°, 60°, and 90°, respectively. The relative resistance change increases approximately linearly with increasing bending angle, but the magnitude of the change is relatively small. This linear response demonstrates the sensor's predictable bending performance, making it suitable for deformation monitoring in flexible electronic devices or wearable technologies. Figure 11 Figures (c) and (d) in the figure verify the long-term stability of the CHT (Cu-HHTP) sensor in terms of stress and bending angle, respectively. After 100 cycles under experimental conditions of a stress of 2N and a bending angle of 60°, the relative resistance change rate of the CHT (Cu-HHTP) sensor remained within a certain range without significant attenuation, indicating that the CHT (Cu-HHTP) sensor maintained its performance after multiple measurements. This cyclic stability enables the sensor to adapt to the needs of different application scenarios, such as structural health monitoring or dynamic load testing. Overall, the CHT (Cu–HHTP) sensor exhibits high sensitivity in both stress and bending angle measurements. Its performance advantage may be due to the unique conductivity and mechanical flexibility of the Cu–HHTP material, giving it broad application potential in flexible electronics, smart sensing and other fields.

[0072] Figure 12The CHT (Cu-HHTP) sensor demonstrates its practical application in human motion monitoring. The sensor's response characteristics were tested using bending motions of the finger, wrist, elbow, and leg. As shown in the figures, the CHT (Cu-HHTP) sensor accurately captures bending motions of different body parts and exhibits a significant rate of change in resistance, demonstrating its potential application in wearable devices and health monitoring. Figure 12 Figure (a) shows the CHT (Cu-HHTP) sensor's measurement of finger bending. The maximum change in amplitude reaches approximately -60% with finger bending. This high sensitivity demonstrates the CHT (Cu-HHTP) sensor's ability to accurately detect subtle finger movements, making it suitable for gesture recognition or fine motor monitoring in rehabilitation training. The steep curve in the figure demonstrates the CHT (Cu-HHTP) sensor's fast response speed, enabling real-time tracking of dynamic movements. Figure 12 Figure (b) shows the CHT (Cu-HHTP) sensor's response to wrist bending. Compared to fingers, the resistance change rate due to wrist bending fluctuates more narrowly (approximately -30%). This characteristic demonstrates that the CHT (Cu-HHTP) sensor can stably capture cyclical wrist motion (such as wrist rotation or flexion and extension), making it suitable for daily activity monitoring or physical activity measurement. Figure 12 Figure (c) depicts the CHT (Cu-HHTP) sensor's performance in measuring elbow flexion. The resistance change rate with flexion is intermediate between that of the finger and wrist (approximately -40%). The high consistency between the CHT (Cu-HHTP) sensor's output and actual motion demonstrates its high reliability in measuring range of motion and potential applications in sports medicine and physical training monitoring. Figure 12 Figure (d) focuses on the test results for leg flexion. The maximum amplitude of the resistance change is approximately -50%, reflecting the large inertia and amplitude of leg movement. The output of the CHT (Cu-HHTP) sensor closely matches the rhythm of leg flexion, demonstrating its suitability for monitoring a wide range of low-frequency movements, such as gait analysis or lower limb rehabilitation training.

[0073] Overall, the CHT (Cu-HHTP) sensor demonstrated good performance in motion measurement at different parts of the human body. Differences in resistance change rates may be related to the amplitude of motion at each site, the intensity of muscle activity, and the local strain distribution to which the CHT (Cu-HHTP) sensor is attached. Furthermore, the CHT (Cu-HHTP) sensor's flexible design and stability enable it to adapt to complex human motion environments without failing due to frequent deformation. These characteristics offer new technological possibilities for wearable health monitoring devices, intelligent prosthetic control, and motion biomechanical analysis. Research can further optimize the wearable comfort and environmental adaptability of CHT (Cu-HHTP) sensors to promote their widespread application in healthcare, sports, and daily life.

[0074] Ti3C2T was prepared x @Cu3(HHTP)2 composite materials, explored the influence mechanism of composite material ratio on conductivity, loading and interface bonding, and revealed the Ti3C2T x The synergistic effect of Cu3(HHTP)2 on the regulation of resistance-stress response characteristics clarifies the structure-activity relationship of flexible functional materials' microstructure, loading process, and sensing performance, providing a theoretical basis for the development of highly sensitive flexible stress and strain sensors. The main conclusions are as follows:

[0075] (1) In the study of the synthesis ratio, T(Cu-HHTP)-3 showed the best sensing performance under both stress and bending conditions. Its stress response sensitivity is due to its dense conductive network and optimized interface contact resistance. Its uniform nanostructure gives it excellent linear response characteristics. x The oriented arrangement of the layers reduces grain boundary scattering and increases the overlap area of the layers, forming a highly efficient one-dimensional conductive path, significantly improving axial conductivity. However, transverse stretching (T-axis) limits performance due to reduced contact area and interfacial transport barriers. The introduction of Cu3(HHTP)2 not only enhances interfacial bonding, but its porous structure also improves material durability through stress buffering.

[0076] (2) The optimized process is the loading process: x @Cu3(HHTP)2 concentration 4mg / mL, treated for 20min, adsorbed 3 times. SEM results show that the original cotton fiber surface is smooth. x After treatment, a nanosheet structure is formed and the roughness increases; low concentration Ti3C2T x When treated with Cu3(HHTP)2, Cu3(HHTP)2 particles are dispersed, while at high concentrations, a dense nanoparticle layer is formed, which completely covers the Ti3C2T x The structure of flexible functional materials shows a gradient evolution, Ti3C2Tx Anchoring Cu3(HHTP)2 particles as a conductive interlayer further optimizes the surface chemistry but may lead to a decrease in fiber flexibility.

[0077] (3) The maximum resistance change rate of the sensor reaches 60%, showing a sensitivity jump characteristic in the high stress area; the bending response has a linear change rate of 6%, showing stable deformation detection capabilities. The long-term stability measurement of the resistance change rate after 100 uses shows almost no attenuation. Human motion monitoring confirms that the sensor can accurately capture the movements of different parts of the body: the finger bending response is the most sensitive (-60%), and the wrist (-30%), elbow (-40%) and leg (-50%) all show fast response and periodic repeatability. The performance advantage comes from Ti3C2T x Synergistic effect of Ti3C2T composite conductive network with Cu3(HHTP)2 x Providing a highly conductive substrate, Cu3(HHTP) enhances interface bonding and stress buffering, giving the material high sensitivity and mechanical adaptability.

[0078] The above describes in detail the preferred embodiments of the present invention. It should be understood that those skilled in the art can make numerous modifications and variations based on the concepts of the present invention without inventive effort. Therefore, any technical solutions that can be derived by those skilled in the art through logical analysis, reasoning, or limited experimentation based on the concepts of the present invention and the prior art should be within the scope of protection defined by the claims.

Claims

1. A method for preparing a MXene-metal organic framework composite material, characterized in that: Ti3C2T x @Cu3(HHTP)2 is added to ultrapure water to prepare a certain concentration of Ti3C2T x @Cu3(HHTP)2 dispersion, the pretreated textile fabric was placed on Ti3C2T x @Cu3(HHTP)2 dispersion for a certain time, take it out and dry it to obtain Ti3C2T x @Cu3(HHTP)2 flexible functional material.

2. The method for preparing a MXene-metal organic framework composite material according to claim 1, wherein: The pretreatment of the textile fabric is to place the textile fabric in an alkaline solution, heat and boil it, take it out, wash and dry it, then wash the textile fabric in an ethanol solution, take it out and dry it again; then place the textile fabric in a HACC solution for a certain period of time, rinse it, take it out and vacuum dry it.

3. The method for preparing a MXene-metal organic framework composite material according to claim 1, wherein: The Ti3C2T x The preparation process of @Cu3(HHTP)2 is as follows: Few-layer Ti3C2T x Evenly dispersed in deionized water, a few-layer Ti3C2T x Solution, Cu(CO2CH3)2·H2O and 0.0357 g HHTP were dissolved in deionized water and ethanol solution, respectively, to obtain Cu(CO2CH3)2·H2O solution and HHTP solution; Few-layer Ti3C2T x The solution and the HHTP solution were mixed and ultrasonically dispersed to form a mixed solution; Cu(CO2CH3)2·H2O solution was added dropwise to the mixed solution under ultrasonic conditions and ultrasonically dispersed, and then the reaction solution was placed in a water bath and reacted under stirring conditions, and then the suspension was centrifuged and washed with ethanol / deionized water solution and then with deionized water to remove residual H3BTC and copper acetate; the product after centrifugation was vacuum dried to obtain Ti3C2T x @Cu3(HHTP)2.

4. The method for preparing a MXene-metal organic framework composite material according to claim 3, wherein: The few-layer Ti3C2T x The preparation process is as follows: Dissolve LiF in hydrochloric acid and stir to fully dissolve it to obtain a LiF solution; The LiF solution is poured into a polytetrafluoroethylene reactor, which is placed in a water bath and heated to a set temperature. Then, Ti3AlC2 is added to the reactor and stirred at the set temperature to obtain a reaction solution. The reaction solution is poured into a centrifuge tube, washed with dilute hydrochloric acid to remove excess LiF, and then washed with deionized water and centrifuged until the pH of the solution is greater than or equal to 6. The precipitate is collected and dissolved in deionized water to obtain Ti3C2T x solution; Under nitrogen protection, Ti3C2T x The solution was ultrasonicated in an ultrasonic disperser, and then Ti3C2T x The solution was centrifuged and the upper liquid was collected. It was freeze-dried in vacuum to obtain a few-layer Ti3C2T x .

5. The method for preparing a MXene-metal organic framework composite material according to claim 3, wherein: The Ti3C2T x The mass ratio of Cu(CO2CH3)2·H2O is 1:0.25-1.

6. A flexible functional device, characterized in that: Including Ti3C2T prepared by any one of claims 1-5 x @Cu3(HHTP)2 flexible functional material.

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