Preparation method of flexible functional material based on in-situ modified nanosheet layer and sensing device

Abstract

The invention discloses a preparation method of a flexible functional material based on an in-situ modified nanosheet layer and a sensing device, and the preparation method of the flexible functional material comprises the following steps: adding Ti3C2Tx-coated Cu3 (BTC) 2 into ultrapure water to prepare a Ti3C2Tx-coated Cu3 (BTC) 2 dispersion liquid with a certain concentration, putting a pretreated textile fabric into the Ti3C2Tx-coated Cu3 (BTC) 2 dispersion liquid for a certain time, taking out and drying to obtain the Ti3C2Tx-coated Cu3 (BTC) 2 flexible functional material. Ti3C2Tx-coated Cu3 (BTC) 2 is adsorbed on a textile fabric based on a preparation process of electrostatic adsorption, and is used for preparing a Ti3C2Tx-coated Cu3 (BTC) 2 flexible functional material with high porosity and high sensitivity. And the sensitivity meets the medical monitoring precision requirement of + / -0.1 DEG C. The performance advantages of the sensor are derived from Ti3C2Tx providing a high-conductivity substrate and Cu3 (BTC) 2 enhancing an interface band gap, so that the change rate of carriers of the whole unit temperature is increased, and the material is endowed with high temperature sensitivity.

Description

Technical Field

[0001] The invention relates to a preparation method of a flexible functional material based on in-situ modified nanosheets and a sensor device, belonging to the technical field of preparation of flexible functional materials for temperature sensors. 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, and blood sugar, 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 their significant advantages, 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 T x) 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] Among the many remarkable properties of MXenes, their widest range of Young's modulus, tunable bandwidth, and enhanced electrical and thermal conductivity are considered to have unique advantages. Notably, the hydrophilicity of MXenes combined with their enhanced thermal conductivity distinguishes them from other two-dimensional materials, including graphene.

[0008] In recent years, metal-organic frameworks (MOFs), as highly tunable porous materials, have been gradually introduced into the research of MXene composites. MOFs, composed of metal ions or metal clusters coordinated with organic ligands to form two- or three-dimensional structures, possess extremely high surface area and porosity, providing abundant active sites. In the field of sensors, the porous structure of MOFs effectively increases the surface area of the material, enhancing its interaction with the environment, thereby improving the sensitivity and response speed of the sensor. Combining MOFs with MXenes can achieve complementary advantages: MXene provides excellent conductivity and mechanical strength, while MOFs, through their porous structure and tunable surface properties, enhance sensor sensitivity, response speed, and stability. Furthermore, MOFs can enhance the structural stability of MXene, effectively preventing its performance degradation over long-term use. Several studies have experimentally verified the application of MXene@MOFs materials in temperature and gas sensors. Zhang Shuai et al. from the University of Jinan combined MOFs-prepared In2O3 / ZnO hollow nanotubes and Ti3C2T x The advantages of MOFs were used to successfully prepare a gas sensor. The sensor can accurately monitor ethanol in the air at room temperature. In addition, the sensor also showed good selectivity and reproducibility for ethanol. Combined with DFT calculations, the adsorption energy (Eads) was used to prove that the MOFs-derived In2O3 / ZnO and Ti3C2T x The synergistic effect between them effectively improves the sensing performance of the sensor for ethanol.

[0009] How to make MXene@MOFs materials into flexible functional materials and apply them to the field of flexible smart wearable temperature sensing has become a problem to be solved. Summary of the Invention

[0010] The purpose of the present invention is to provide a method for preparing a flexible functional material based on in-situ modified nanosheets, wherein the prepared flexible functional material has high temperature sensitivity.

[0011] In order to solve the above-mentioned technical problems, the purpose of the present invention is achieved as follows:

[0012] The present invention relates to a method for preparing a flexible functional material based on in-situ modified nanosheets, wherein Ti3C2T x @Cu3(BTC)2 is added to ultrapure water to prepare a certain concentration of Ti3C2T x @Cu3(BTC)2 dispersion, the pretreated textile fabric is placed on Ti3C2T x @Cu3(BTC)2 dispersion for a certain time, take it out and dry it to obtain Ti3C2T x @Cu3(BTC)2 flexible functional material.

[0013] 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.

[0014] On the basis of the above scheme and as a preferred scheme of the above scheme: the Ti3C2T x The preparation process of @Cu3(BTC)2 is as follows:

[0015] Few-layer Ti3C2T x Evenly dispersed in deionized water, a few-layer Ti3C2T x solution, dissolving Cu(CO2CH3)2·H2O and H3BTC in deionized water and ethanol solution, respectively, to obtain Cu(CO2CH3)2·H2O solution and H3BTC solution;

[0016] Few-layer Ti3C2T xThe solution and the H3BTC solution were mixed and ultrasonically dispersed to form a mixed solution; the Cu(CO2CH3)2·H2O solution was added dropwise to the mixed solution under ultrasonic conditions, and then the mixed solution was placed under ultrasonic conditions to react for a certain time to form a suspension, and then the suspension was centrifuged and washed with ethanol / deionized water solution and then with deionized water to remove residual H3BTC and Cu(CO2CH3)2·H2O; the product after centrifugation was freeze-dried in a vacuum to obtain Ti3C2T x @Cu3(BTC)2.

[0017] 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:

[0018] Dissolve LiF in hydrochloric acid and stir to fully dissolve it to obtain a LiF solution;

[0019] 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;

[0020] Under nitrogen protection, Ti3C2T x The solution was ultrasonicated in an ultrasonic disperser for 2 h, and then Ti3C2T x The solution was centrifuged and the upper liquid was collected. It was freeze-dried in vacuum for 48 hours to obtain a few-layer Ti3C2T x .

[0021] 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.

[0022] The present invention also relates to a sensor device for temperature sensing, comprising Ti3C2T prepared by the above preparation method. x @Cu3(BTC)2 flexible functional material.

[0023] The beneficial effects of the present invention are as follows: the preparation method of the flexible functional material based on in-situ modified nanosheet and the sensor device of the present invention make Ti3C2T x @Cu3(BTC)2 is adsorbed on textile fabrics to prepare three-dimensional flexible Ti3C2T with high porosity and high sensitivityx @Cu3(BTC)2 flexible functional material. Its sensitivity meets the medical monitoring accuracy requirement of ±0.1℃. The sensor performance advantage comes from Ti3C2T x Providing a highly conductive substrate, Cu3(BTC)2 enhances the interface band gap, increases the overall rate of change of carriers per unit temperature, and gives the material high temperature sensitivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a few-layer Ti3C2T x TEM images, SEM images and EDS element distribution maps;

[0025] Figure 2 It is a few-layer Ti3C2T x IR spectrum and XRD spectrum of

[0026] Figure 3 It is a few-layer Ti3C2T x XPS spectrum of

[0027] Figure 4 The Ti3C2T prepared in Example 3 x TEM, SEM and EDS element distribution of @Cu3(BTC)2;

[0028] Figure 5 The Ti3C2T prepared in Example 3 x @Infrared spectrum and XRD spectrum of Cu3(BTC)2 and Cu3(BTC)2 prepared in Comparative Example 1;

[0029] Figure 6 The Ti3C2T prepared in Example 3 x XPS spectra of Cu3(BTC)2 and Cu3(BTC)2 prepared in Comparative Example 1;

[0030] Figure 7 The resistance variation with temperature curve, relative resistance variation rate with temperature curve and linear fitting diagram of CHT-0, CHTH-1, CHTH-2, CHTH-3 and CHTH-4 in the range of 25℃-60℃ are shown;

[0031] Figure 8 is the fitting of the ln(I)-1 / T curves of CHT-0, CHTH-1, CHTH-2, CHTH-3, and CHTH-4 and the CHTH-2 curve;

[0032] Figure 9 is a graph showing the relationship between adsorption concentration, treatment time, adsorption times, loading amount, and resistance in Examples 11-28;

[0033] 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;

[0034] Figure 11 It is the CHTH temperature sensor characteristic;

[0035] Figure 12 It is the application of CHTH temperature sensor in real-time temperature monitoring of human wrist temperature. DETAILED DESCRIPTION

[0036] The present invention will be further described below with reference to the accompanying drawings and specific embodiments.

[0037] The present invention relates to a method for preparing a flexible functional material based on in-situ modified nanosheets, wherein Ti3C2T x @Cu3(BTC)2 is added to ultrapure water to prepare a certain concentration of Ti3C2T x @Cu3(BTC)2 dispersion, the pretreated textile fabric is placed on Ti3C2T x @Cu3(BTC)2 dispersion for a certain time, take it out and dry it to obtain Ti3C2T x @Cu3(BTC)2 flexible functional material.

[0038] Few-layer Ti3C2T was prepared by lithium fluoride and hydrochloric acid etching. x , using room temperature diffusion method to make Cu3(BTC)2 in few-layer Ti3C2T x The Ti3C2T nanosheets were generated in situ. x @Cu3(BTC)2 composite material.

[0039] Example 1

[0040] 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 Ti3C2Tx 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 .

[0041] 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 x The 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.

[0042] right Figure 2 Ti3C2T shown in (a) and (b) x The infrared spectrum (FTIR) and X-ray diffraction (XRD) spectrum analysis showed that the material has a typical few-layer structure and surface chemical characteristics. In the infrared spectrum, the wavelength of 3450cm -1 The broad peak near 1630 cm corresponds to the OH stretching vibration, indicating the presence of hydroxyl groups on the surface or between layers of the material; -1 The absorption peak at 1200 cm corresponds to the C=O stretching vibration, indicating the presence of carboxylic acid or carbonyl functional groups on the surface of the material. -1No significant CF bond vibration peaks were observed near the 600–400 cm-1 region, 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. -1 The weak peaks in the range are related to the skeleton vibration of Ti-O or Ti-C, reflecting the Ti3C2T x integrity of the crystal structure.

[0043] 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.

[0044] 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 3 The 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.

[0045] Examples 2-5

[0046] Examples 2-5 involve Ti3C2T x The preparation process of @Cu3(BTC)2 is as follows: 0.03g of the few-layer Ti3C2T prepared in Example 1 is added x Evenly dispersed in 10 ml of deionized water, a few-layer Ti3C2T x Solution, 0.03gCu(CO2CH3)2·H2O and 0.021gH3BTC (pyromellitic acid) were dissolved in 10ml deionized water solution and 10ml ethanol solution respectively. x The solution and H3BTC solution were mixed in a 60ml glass bottle and ultrasonically dispersed for 30min to make it uniformly dispersed in the mixed solution. After that, Cu(CO2CH3)2·H2O solution was added dropwise to the above mixed solution under ultrasonic conditions, and then placed under ultrasonic conditions for reaction for 1h. The suspension was then centrifuged at 2000rpm / min for 5min, washed 3 times with ethanol / deionized water (1:2v / v) solution and 3 times with deionized water to remove residual H3BTC and Cu(CO2CH3)2·H2O. The centrifuged product was then freeze-dried in a vacuum for 12h to obtain Ti3C2T x @Cu3(BTC)2.

[0047] 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.

[0048] Comparative Example 1

[0049] This comparative example relates to a method for preparing Cu3(BTC)2. The specific preparation process is as follows: 0.03g of Cu(CO2CH3)2·H2O and 0.021g of H3BTC (pyromellitic acid) were dissolved in 10ml of deionized water and 10ml of ethanol, respectively. The H3BTC solutions were first mixed in a 60ml glass bottle and ultrasonically dispersed for 30 minutes to uniformly disperse the mixture. Subsequently, the Cu(CO2CH3)2·H2O solution was added dropwise to the mixed solution under ultrasonic conditions. The mixture was then subjected to ultrasonic reaction for 1 hour. The suspension was then centrifuged at 2000 rpm / min for 5 minutes and washed three times with an ethanol / deionized water (1:2 v / v) solution and three times with deionized water to remove residual H3BTC and Cu(CO2CH3)2·H2O. The centrifuged product was then freeze-dried in a vacuum for 12 hours to obtain Cu3(BTC)2.

[0050] like Figure 4 As shown, the Ti3C2T prepared in Example 3 x @Cu3(HHTP)2 was used for morphological characteristics and elemental composition analysis. Figure 4 (a)-(c) show Ti3C2T at different magnifications. x @Cu3(HHTP)2 transmission electron microscopy (TEM) images clearly show the microstructure of the material through different magnifications, showing that Ti3C2T x Closely combined with Cu3(BTC)2, and Ti3C2T x The Cu3(BTC)2 is uniformly coated to form a core-shell structure. High-magnification TEM images further reveal the lattice fringes and pore distribution of the material, indicating that the composite material has high crystallinity and porosity. Figure 4 The scanning electron microscope (SEM) shown in (b) shows the overall morphology of the material from a macroscopic perspective, showing the morphological characteristics of lamellar or granular aggregation, with a rough surface and rich pore structure, further verifying the TEM observation results. Figure 4 The EDS element analysis diagram shown in (c) confirms the presence and distribution of the main elements (such as Ti, C, O, Cu, etc.) in the material through energy spectrum detection, proving the successful loading of Cu3(BTC)2 and the Ti3C2T x Chemical compatibility with Cu3(BTC)2. Taken together, these characterization results preliminarily confirm that Ti3C2T x Successful preparation of @Cu3(BTC)2 composite material.

[0051] In order to further study Ti3C2T xThe structure and properties of @Cu3(BTC)2 composite materials were characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The results of Fourier transform infrared spectroscopy FTIR are as follows Figure 5 As shown in (a). Ti3C2T x @Cu3(BTC)2 at 1654cm -1 and 1584cm -1 The peak at is attributed to COO - The asymmetric stretching vibration peak of 1453 cm -1 and 1375cm -1 The peak at - are symmetrical stretching vibration peaks. The presence of these peaks indicates that Ti3C2T x @Cu3(BTC)2 contains Cu 2+ and COO - Chelation of Cu3(BTC)2 and Ti3C2T x The X-ray diffraction (XRD) results of @Cu3(BTC)2 are as follows: Figure 5 As shown in (b), the diffraction pattern of Cu3(BTC)2 is consistent with the literature data. It is worth noting that Ti3C2T x Ti3C2T@Cu3(BTC)2 composites x The intensity of most peaks of Ti3C2T is weakened because its content is lower than that of pure Ti3C2T x The broad peak near 7.1° is caused by Ti3C2T x The (002) crystal plane of Ti3C2T moves at a low angle and overlaps with the (200) crystal plane of Cu3(BTC)2. x The existence of (200), (220) and (222) crystal planes of Cu3(BTC)2 indicates that Cu3(BTC)2 x The crystal structure grown on Cu3(BTC)2 is exactly the same as that when Cu3(BTC)2 exists alone, both are cubic crystal structures.

[0052] like Figure 6 As shown, X-ray photoelectron spectroscopy was used to characterize Cu3(BTC)2 and Ti3C2T x @Cu3(BTC)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 peaks of F1s and Ti 2p also appeared in the spectrum of @Cu3(BTC)2, which indicates that the material contains Ti3C2T x and F groups introduced by HF. Figure 6(b) shows Cu3(BTC)2 and Ti3C2T x @Cu3(BTC)2 C1s spectrum: The peaks of Cu3(BTC)2 at 284.2eV, 285.3eV, 287.8eV and 288.3eV correspond to C=C, CC, C=O and O=CO respectively; while Ti3C2T x A new peak appeared at 281.7 eV for @Cu3(BTC)2, which was attributed to the C-Ti bond. Figure 6 (c) shows the O1s spectrum, where Ti3C2T x @Cu3(BTC)2 corresponds to lattice oxygen (O1), oxygen defect (O2) and surface adsorbed oxygen (O3) at 529.65eV, 531.5eV and 532.9eV 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(BTC)2, further confirming that Ti3C2T x Successful synthesis of @Cu3(BTC)2 material. Figure 6 (d) shows the Cu 2p spectrum, showing that the peak at 934.9 eV indicates that the Cu in Cu3(BTC)2 is mainly in the form of Cu 2+ The satellite peak near 943eV further confirms the existence of Cu 2+ The existence of Ti3C2T x A peak appeared at 932.3eV in @Cu3(BTC)2, which indicates that Ti3C2T x The surface is rich in reducing functional groups (such as -O, -OH) and defect sites, and part of Cu in Cu3(BTC)2 is converted to Cu 2+ Reduction to Cu + In addition, according to the comparison of satellite peak intensity, Ti3C2T x @Cu3(BTC)2 in Cu 2+ The proportion of Cu3(BTC)2 is lower than that of pure Cu3(BTC)2.

[0053] Ti3C2T was prepared by room temperature diffusion method. x @Cu3(BTC)2 composite material, the microstructure of the material was clearly observed by transmission electron microscopy, showing that Ti3C2T x Closely combined with Cu3(BTC)2, and Ti3C2T x Uniformly coated on Cu3(BTC)2, forming a core-shell structure. x @Cu3(BTC)2 at 1654cm -1 and 1584cm -1 The peak at is attributed to COO -The asymmetric stretching vibration peak of 1453 cm -1 and 1375cm -1 The symmetrical stretching vibration peak at is attributed to COO - , which is consistent with previous research results. This shows that Ti3C2T x @Cu3(BTC)2 contains Cu 2+ and COO - XPS confirmed that Cu 2+ With Ti3C2T x After the OH- on the surface is combined, H3BTC and Ti3C2T x The Cu on the surface reacts to form Cu-BTC, and then the Cu in the solution 2+ Continue to combine and grow into Cu3(BTC)2 particles.

[0054] Examples 6-10

[0055] The preparation method of the flexible functional material based on in-situ modified nanosheets involved in Examples 6-10 includes the pretreatment of textile fabrics and Ti3C2T x Preparation of @Cu3(BTC)2 flexible functional materials.

[0056] The textile fabric pretreatment process is as follows: 5 x 8 cm fabric swatches, pre-cut, are placed in a 20 g / L caustic soda solution at a bath ratio of 1:30, heated to 100°C and boiled for 1 hour. The swatches are then washed with warm and then cold water and dried. The cotton fabric is then thoroughly washed in a 20% by volume ethanol solution and dried at 80°C for 2 hours. The fabric is then exposed to a 1 mg / mL HACC (chitosan quaternary ammonium salt) solution for 10 minutes, rinsed three times, and dried in a vacuum oven at 80°C for 2 hours.

[0057] Ti3C2T x Preparation of @Cu3(BTC)2 flexible functional materials: Take Ti3C2T x @Cu3(BTC)2 was added to ultrapure water to prepare Ti3C2T x @Cu3(BTC)2 dispersion was ultrasonically dispersed for 0.5h, and the cotton fabric was treated for 20min under ultrasonic dispersion conditions, with one adsorption cycle, and then dried at 80℃ for 2h. x @Cu3(BTC)2 are Ti3C2T prepared in different proportions in Examples 2-5 x @Cu3(BTC)2. In the preparation of Ti3C2T x @Cu3(BTC)2, Ti3C2T xThe mass ratios with Cu(CO2CH3)2·H2O are 1:0.25, 1:0.5, 1:0.75, and 1:1 respectively, and different ratios of Ti3C2T x @Cu3(BTC)2 composites can be obtained.

[0058] The fabric samples prepared using different ratios are named CHTH-1, CHTH-2, CHTH-3, and CHTH-4.

[0059] Comparative Example 2

[0060] The preparation method of the flexible functional material involved in this comparative example, as a control sample, is different from that of Example 6 in that a 1 mg / mL Ti3C2T x dispersion liquid is used, and the fabric prepared is named CHT-0.

[0061] Figure 7 In (a), the curves of the resistance versus temperature of five materials, CHT-0, CHTH-1, CHTH-2, CHTH-3, and CHTH-4, within the temperature range of 25 °C to 60 °C are shown. Overall, the resistance values of all materials show a gradually increasing trend with the increase in temperature, but there are differences in the resistance growth rate and curve shape of different materials. At the initial temperature of 25 °C, the resistance values of each material increase in the order of CHT-0 < CHTH-1 < CHTH-2 < CHTH-3 < CHTH-4, indicating that the initial resistance of the CHTH series materials is higher than that of the base material CHT-0. As the temperature rises to 60 °C, the resistance of all materials continues to increase. Among them, the resistance growth rate of CHT-0 is the smallest, while that of CHTH-2 is the largest. At the same temperature, the resistance values of the CHTH series are always higher than those of CHT-0, and with the increase in the proportion of Cu3(BTC)2, the resistance value gradually increases. Figure 7 In (b), the curves of the relative resistance change rate versus temperature of the above materials and their linear fitting results are further shown. The fitting equations of the linear fitting lines are shown in Table 1.

[0062] Table 1 Linear fitting lines of the curves of the resistance change rate versus temperature

[0063]

[0064] The relative resistance change rates of all materials are positively correlated with temperature and have a high linear fitting degree. The slope of the fitting line reflects the sensitivity of the material's resistance to temperature. The slope of the fitting line of CHT-0 is the smallest, indicating that its resistance has the lowest sensitivity to temperature changes; while the slope of the CHTH series materials first increases and then decreases with the increase in the proportion of Cu3(BTC)2, and the slope of CHTH-2 is the largest, indicating that it is the most sensitive to temperature changes.

[0065] Through the above experimental research, Ti3C2T x The working principle of @Cu3(BTC)2 flexible functional materials is that heat excites semiconductor carriers, thereby reducing resistance to achieve temperature response. The carrier concentration can be calculated using the following formula:

[0066]

[0067] where n i is the intrinsic carrier concentration, Nc and Nv are the conduction band and valence band carrier concentrations respectively, Eg is the band gap, K B is the Boltzmann constant. For a specific semiconductor material, Nc, Nv, and Eg are constants, and the carrier concentration transitioning to the conduction band follows the Boltzmann distribution. This formula shows that increasing temperature increases the concentration of thermally excited carriers, and the wider the band gap, the more significant the change in carrier concentration (or resistance). To further analyze the parameter relationship, we can derive formula (3-1) to obtain:

[0068]

[0069] Where n0 and T0 are the initial carrier concentration and initial temperature, respectively.

[0070] It is found from formula (3-3) that the logarithm of carrier concentration ln(n i ) is significantly linearly correlated with the inverse of temperature 1 / T. Since it is impossible to directly measure n, which is positively correlated with current I i , Figure 8 (a) shows the ln(I)-1 / T curves of CHT, CHTH-1, CHTH-2, CHTH-3 and CHTH-4, which intuitively shows the Ti3C2T x The intrinsic relationship between the carrier excitation characteristics and temperature response of flexible functional materials. Figure 8 (b) CHTH-2 showed a good linear relationship (R 2 =0.99), which verifies the theoretical prediction of formula (3-3), that is, the logarithm of the carrier concentration has a strict linear correlation with the inverse of the temperature. This linear law originates from the intrinsic thermal excitation mechanism of semiconductor materials: when the temperature rises, the valence band electrons gain enough energy to jump across the band gap (Eg) to the conduction band, and the probability of their transition obeys the Boltzmann distribution, resulting in ln(n i ) is negatively linearly correlated with 1 / T. Specifically, the slope difference of the CHTH series materials reflects the change in their band gap width - the larger the absolute value of the slope, the wider the band gap (Eg = 2 × slope × K B), requiring higher thermal excitation energy, and therefore exhibiting a more significant resistance change rate under the same temperature change. It is worth noting that the slope of CHT-0 is the smallest, indicating that its band gap is narrow and carriers are easily excited; while with the recombination of Cu3(BTC)2 (CHTH-1→CHTH-4), the slope first increases and then decreases, reaching a peak value (-8.3) in CHTH-2, which is consistent with the Figure 8 The slope of the resistance change rate in (a) is completely consistent. This nonlinear evolution can be explained by "interface state regulation": an appropriate amount of Cu3(BTC)2(CHTH-1→CHTH-2) is added to Ti3C2T x Defect states are introduced on the surface. These localized states will capture carriers to form additional potential barriers, which is equivalent to increasing the apparent band gap of the material. However, when Cu3(BTC)2 is excessive (CHTH-3→CHTH-4), the insulating phase forms a continuous network, and the carrier transport is limited to the Cu3(BTC)2 body rather than the interface state, resulting in a decrease in the apparent band gap. Further analysis of the vertical intercept shows that the value range of the CHTH series (-7.0 to -9.4) is significantly lower than that of CHT-0 (-5.0), which corresponds to the pre-exponential factor A in formula (3-2), indicating that the flexible functional material reduces defect states through interface regulation, reduces the carrier trap density, and enhances the amplitude of carrier concentration change per unit temperature change. This synergistic effect enables CHTH-2 to exhibit optimal temperature sensitivity (-0.93% / ℃) in the range of 25–60℃, and its linear response characteristics (R 2 >0.96) and a wide dynamic range (ΔR / R0 up to 35%) provide an ideal material system for the design of flexible temperature sensors.

[0071] Examples 11-16

[0072] The preparation method of the flexible functional material based on in-situ modified nanosheets involved in Examples 11-16: According to the Ti3C2T x @Cu3(BTC)2 was added to ultrapure water to prepare Ti3C2T with different concentrations x @Cu3(BTC)2 dispersion was ultrasonically dispersed for 0.5h. Cotton fabric was treated with ultrasonic dispersion 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.

[0073] Examples 17-22

[0074] 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(BTC)2 was added to ultrapure water to prepare 5mg / mL Ti3C2T x The Cu3(BTC)2 dispersion was ultrasonically dispersed for 0.5 h. 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.

[0075] Examples 23-28

[0076] The preparation method of the flexible functional material based on in-situ modified nanosheets in Examples 23-28: According to the Ti3C2T x @Cu3(BTC)2 was added to ultrapure water to prepare 5mg / mL Ti3C2T x The Cu3(BTC)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.

[0077] Figure 9 The adsorption of Ti3C2T x @Cu3(BTC)2 loading behavior on cotton fabric and its effect on electrical resistance. Figure 9 In (a), it can be seen that as Ti3C2T x @Cu3(BTC)2 concentration increases, and the amount also gradually increases. After the cotton fabric is pretreated by HACC, its surface is rich in -NH3+ functional groups, which react with the negatively charged Ti3C2T x @Cu3(BTC)2 attract each other through electrostatic attraction, making Ti3C2T x @Cu3(BTC)2 can be easily fixed on its surface. According to the trend of resistance gradually decreasing with increasing concentration, considering the Ti3C2T x @Cu3(BTC)2 preparation time, usage concentration and other conditions were selected with a concentration of 5 mg / ml for subsequent experiments. Figure 9 (b) The results of Ti3C2T x The load-bearing capacity of the CHTH flexible functional material after treatment with a Cu3(BTC)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) calculated the Ti3C2T xThe load-bearing capacity of the CHTH flexible functional material treated with a Cu₃(BTC)₂ dispersion solution after 1, 2, 3, 4, 5, and 6 cycles was determined. A line graph of the loading capacity indicates that the adsorption plateau is reached after 4 cycles, and the resistance also reaches a turning point. Therefore, 4 cycles of adsorption were selected as the optimal process, with an adsorption concentration of 5 mg / ml, a treatment time of 20 minutes, and 4 cycles as the optimal process. The fabric sample obtained from this optimal process was named CHTH.

[0078] Figure 10 Scanning electron microscope (SEM) images of the original untreated cotton fabric and the cotton fabric after being 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 was successfully attached to the fiber surface. Figure 10 (c) is the Ti3C2T under the best process conditions x @Cu3(BTC)2 treated cotton fabric. A relatively uniform granular covering layer was formed on the fiber surface treated with low concentration. Cu3(BTC)2 and Ti3C2T x The composite structure of Ti3C2T further increases the specific surface area and porosity of the fiber. x Its composite treatment with Cu3(BTC)2 significantly changed the surface morphology of cotton fabrics, transforming them from smooth fibers to rough or porous structures.

[0079] Using CHTH as a temperature sensing sensor, the thermal response of the CHTH temperature sensor as a wearable temperature sensor in the range of 25℃-60℃ is measured to study its high-precision monitoring of local human body temperature, and to establish a database based on this to monitor human health in real time. Figure 11 (a) shows the resistance-temperature characteristic curve of the CHTH temperature sensor in the range of 25℃~60℃. It can be seen that the resistance shows good monotonicity with temperature change and the change amplitude is significant, indicating that the CHTH temperature sensor has high temperature sensitivity. Figure 11 The relative resistance change rate (ΔR / R0) in (b) and the linear fitting result can be used to quantitatively calculate the temperature coefficient (TCR) of the CHTH temperature sensor. TCR is defined as the corresponding change in resistance when the temperature changes by 1°C, and is calculated according to formula 3-4:

[0080]

[0081] Where R and R0 represent the resistance values at the test temperature T and the initial temperature T0 respectively.

[0082] The CHTH temperature sensor has an ultra-high sensitivity of 1.2% / ℃ and its linear fit goodness R 2 It is close to 1, indicating that the CHTH temperature sensor has excellent linear response characteristics in this temperature range, which is crucial for temperature calibration and signal processing in practical applications.

[0083] In order to study the long-term stability of the CHTH temperature sensor, the resistance change of the CHTH temperature sensor within 300s was measured in a thermostat at 25℃, 30℃, 35℃, 40℃, 45℃, 50℃, and 55℃, as shown in Figure 2. Figure 11 As shown in (c), the resistance change is almost negligible, indicating that the CHTH temperature sensor is stable during long-term continuous monitoring. In order to study the cyclic stability of the CHTH temperature sensor, the resistance change during 5 heating and cooling cycles at 25℃ and 40℃ was tested. Figure 11 The results in (d) show that the response fluctuation of the CHTH temperature sensor in different temperature cycling experiments is negligible, indicating that the CHTH temperature sensor has good cycling stability.

[0084] When the ambient temperature changes instantaneously, the time it takes for the CHTH temperature sensor output signal to change is defined as the response time. Fast response is crucial for real-time health monitoring and labor safety warnings. The response time can be expressed as the time it takes to reach the final temperature in a step change. When the CHTH temperature sensor was heated from 36°C to 40°C, the response time was found to be approximately 33s. Figure 11 As shown in (e). It is better than the recommended usage time of medical mercury thermometer. In order to confirm the accuracy of CHTH temperature sensor in temperature detection, the resistance change is measured in the range of 36℃-37℃. Figure 11 (f) shows the correlation between the observed resistance change and temperature change. The data shows that it can clearly resolve temperature changes of 0.1°C, which indicates that the CHTH temperature sensor has high accuracy.

[0085] The prepared CHTH temperature sensor is integrated into a wristband to continuously and accurately measure the temperature of the human wrist. The test results are as follows Figure 12 shown. Figure 12This chart demonstrates a typical application scenario of a CHTH temperature sensor for real-time wrist temperature monitoring. The left vertical axis of the chart shows the temperature scale, while the right vertical axis shows the relative rate of change in resistance of the CHTH temperature sensor. The horizontal axis covers the daily activity period from 8:00 AM to 8:00 PM. The data shows that the CHTH temperature sensor exhibits temperature fluctuations that closely align with human circadian rhythms during continuous monitoring. The resistance change rate is significantly negatively correlated with temperature, validating the sensor's operating principle based on a thermosensitive material (presumably NTC)—for every 1°C increase in temperature, the resistance decreases by approximately 1.8%. Its sensitivity meets the medical monitoring accuracy requirement of ±0.1°C. This approach offers significant advantages over traditional underarm or oral temperature measurement: non-invasive measurement avoids discomfort, continuous monitoring captures dynamic changes in body temperature, and the wristband's ease of wear significantly improves user compliance. In the future, by arraying multiple CHTH sensors at different locations on the wristband, it is possible to eliminate measurement errors caused by poor local contact and further enhance data reliability. Furthermore, by combining machine learning algorithms with analysis of long-term temperature data, it is expected to provide early warning of infectious diseases such as influenza and COVID-19, pushing wearable devices from health monitoring to disease prevention. This smart wristband, based on a high-performance temperature sensor, not only provides a new tool for personal health management but also provides key technical support for applications such as telemedicine and smart elderly care.

[0086] Ti3C2T was prepared by using flexible and easily adsorbable cotton fabric and room temperature diffusion method. x @Cu3(BTC)2 composite material, based on the preparation process of electrostatic adsorption to make Ti3C2T x @Cu3(BTC)2 was adsorbed on cotton fabric to prepare three-dimensional flexible Ti3C2T with high porosity and high sensitivity. x @Cu3(BTC)2 flexible functional materials. x Effect of the synthesis ratio of @Cu3(BTC)2 on Ti3C2T x @Cu3(BTC)2 flexible functional materials and the performance of Ti3C2T x The microstructure and temperature sensing properties of @Cu3(BTC)2 flexible functional materials were studied, and their applications in flexible smart wearable temperature sensing were further explored. The main conclusions are as follows:

[0087] (1) In the discussion of the synthesis ratio, CHTH-2 showed the best temperature sensing performance. The optimized process is the loading process: x @Cu3(BTC)2 concentration of 5mg / mL, treated for 20min, adsorbed 4 times. SEM results show that the surface of the original cotton fiber is smooth. xAfter treatment, a nanosheet structure is formed and the roughness increases; low concentration Ti3C2T x When treated with @Cu3(BTC)2, Cu3(BTC)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, Ti3C2T x Anchoring Cu3(BTC)2 particles as a conductive interlayer further optimizes the surface chemistry.

[0088] (2) The sensor exhibits the best temperature sensitivity (-1.20499% / ℃) in the range of 25–60℃, and its linear response characteristic (R 2 >0.97) and a wide dynamic range (ΔR / R0 up to 45%) provide an ideal material system for flexible temperature sensor design. Human wrist temperature monitoring confirms that the sensor's resistance decreases by approximately 1.8% for every 1°C increase in temperature. Its sensitivity meets the ±0.1°C medical monitoring accuracy requirement. The sensor's performance advantage stems from the Ti3C2T x Providing a highly conductive substrate, Cu3(BTC)2 enhances the interface band gap, increases the overall rate of change of carriers per unit temperature, and gives the material high temperature sensitivity.

[0089] 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 flexible functional materials based on in-situ modified nanosheets, characterized in that: Ti3C2T x @Cu3(BTC)2 is added to ultrapure water to prepare a certain concentration of Ti3C2T x @Cu3(BTC)2 dispersion, the pretreated textile fabric is placed on Ti3C2T x @Cu3(BTC)2 dispersion for a certain time, take it out and dry it to obtain Ti3C2T x @Cu3(BTC)2 flexible functional material.

2. The method for preparing a flexible functional material based on in-situ modified nanosheets according to claim 1, characterized in that: 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 flexible functional materials based on in-situ modified nanosheets according to claim 1, characterized in that: The Ti3C2T x The preparation process of @Cu3(BTC)2 is as follows: Few-layer Ti3C2T x Evenly dispersed in deionized water, a few-layer Ti3C2T x solution, dissolving Cu(CO2CH3)2·H2O and H3BTC in deionized water and ethanol solution, respectively, to obtain Cu(CO2CH3)2·H2O solution and H3BTC solution; Few-layer Ti3C2T x The solution and the H3BTC solution were mixed and ultrasonically dispersed to form a mixed solution; the Cu(CO2CH3)2·H2O solution was added dropwise to the mixed solution under ultrasonic conditions, and then the mixed solution was placed under ultrasonic conditions to react for a certain time to form a suspension, and then the suspension was centrifuged and washed with ethanol / deionized water solution and then with deionized water to remove residual H3BTC and Cu(CO2CH3)2·H2O; the product after centrifugation was freeze-dried in a vacuum to obtain Ti3C2T x @Cu3(BTC)2.

4. The method for preparing a flexible functional material based on in-situ modified nanosheets according to claim 3, characterized in that: 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 flexible functional materials based on in-situ modified nanosheets according to claim 3, characterized in that: The Ti3C2T x The mass ratio of Cu(CO2CH3)2·H2O is 1:0.25-1.

6. A sensor device for temperature sensing, characterized in that: Comprising Ti3C2T prepared according to any one of claims 1 to 5 x @Cu3(BTC)2 flexible functional material.

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