Mxene-ss / sf composite material, preparation method and application thereof

Abstract

The application discloses a kind of MXene-SS / SF composite material and its preparation method and application, MXene-SS / SF composite material is the laminated nanocomposite film with continuous wrinkle distributed on surface, the mass ratio of SS and SF in MXene-SS / SF composite material is 1:2, SS is the silk glue protein separated after silk alkali, SF is silk fibroin, the composition structure of MXene is Ti3C2T x ;MXene-SS / SF composite material can be used as sensing humidity layer in physical detection.The MXene-SS / SF composite material of the application has continuous electron transport channel, higher porosity and larger specific surface area under the support of structural protein, the functional groups existing on the surface give it more active sites, with significant conductivity, good hydrophilicity;The sensor constructed by MXene-SS / SF composite material has high sensitivity in humidity detection, wide detection limit, has excellent response and recovery performance in humidity detection, and has great application potential in the field requiring rapid humidity detection.

Description

TECHNICAL FIELD

[0001] The application relates to a composite material and a preparation method and application thereof, in particular to an MXene-SS / SF composite material and a preparation method and application thereof. BACKGROUND

[0002] In non-contact human-computer interaction and public safety, precision medicine and industrial production, it is very important to design a sensing humidity material with high sensitivity, wide detection limit and high response to detect humidity.

[0003] As a new member of inorganic 2D materials, MXene has become an excellent candidate material in the field of intelligent sensing due to its unique structural characteristics, hydrophilicity and physical and chemical properties such as high specific surface area and metal conductivity. However, MXene is easily oxidized in a water-oxygen environment, which leads to unstable sensing, and cannot be ignored when designing composite materials for actual humidity sensing applications. Biomass materials have been favored by more and more researchers in different fields in recent years due to their environmental friendliness, wide source, renewability and relatively low cost. The introduction of two-dimensional materials into natural biopolymers improves the function of the material.

[0004] For example, Fe3O4-COOH nanoparticles are loaded on the surface of MXene, which effectively alleviates the restacking phenomenon of MXene nanosheets in aqueous solution, and generates a PAAm hydrogel with good stability without using any initiator. Fe3O4-COOH@MXene nanosheets as conductive fillers, cross-linking agents and catalysts for rapid gelation of hydrogels make the obtained FM@SF-PAAM hybrid hydrogel have good conductivity (6.44·10 -2 S·m -1 ). However, it has certain limitations: although the strong connection of the polymer chains formed in the cross-linking process of the hydrogel makes them insoluble in water, the presence of hydrophilic functional groups makes them can absorb a large amount of solvent, but due to exposure to air, the evaporation of the solvent will reduce the water content in the hydrogel structure, which will affect its conductivity. In addition, acrylamide monomers have certain toxicity, and improper handling will have the risk of poisoning. SUMMARY

[0005] The application aims to provide an MXene-SS / SF composite material and a preparation method and application thereof, which can realize a composite material with significant conductivity, good hydrophilicity and good oxidation stability.

[0006] Technical scheme: The MXene-SS / SF composite material provided by the application is a laminated nanocomposite film with continuous wrinkles distributed on the surface, and the mass ratio of SS to SF in the MXene-SS / SF composite material is 1:2.

[0007] As a further limited scheme of the composite material of the present application, the thickness of the MXene-SS / SF composite material is less than 10 nm.

[0008] As a further limited scheme of the composite material of the present application, the nitrogen-containing silk fibroin in the MXene-SS / SF composite material is uniformly distributed with the MXene sheet layer, and the beta-sheet secondary structure of the silk fibroin extends through the edge of the MXene sheet layer and forms a nanofibril long edge around a single MXene sheet layer.

[0009] The present application also provides a preparation method of a MXene-SS / SF composite material, for preparing a MXene-SS / SF composite material, comprising the following steps:

[0010] Step 1, preparing a MXene nanosheet dispersion liquid;

[0011] Step 2, adding SS solution and SF solution to the MXene nanosheet dispersion liquid to obtain a two-dimensional layered MXene-SS / SF composite material by mixing self-assembly.

[0012] As a further limited scheme of the preparation method of the present application, in step 1, the specific steps for preparing the MXene nanosheet dispersion liquid are as follows:

[0013] Step 1.1, uniformly mixing titanium aluminum carbide and lithium fluoride according to a set mass ratio;

[0014] Step 1.2, after uniform mixing, adding to hydrochloric acid in a reaction kettle and etching at high temperature in a hydrochloric acid environment;

[0015] Step 1.3, obtaining MXene nanosheets after washing and centrifugal treatment;

[0016] Step 1.4, ultrasonic dispersion of the MXene nanosheets in ultrapure water to obtain a MXene nanosheet dispersion liquid.

[0017] As a further limited scheme of the preparation method of the present application, in step 1.1, the mass ratio of titanium aluminum carbide and lithium fluoride is 1:1.6.

[0018] As a further limited scheme of the preparation method of the present application, in step 1.2, the concentration of hydrochloric acid is 12 mol / L, the etching time is 12-24 h, the heating temperature in the reaction kettle is 40-50℃, and the stirring speed is 450-550 r / min.

[0019] As a further limited scheme of the preparation method of the present application, in step 1.4, the mass ratio of MXene nanosheets to ultrapure water is 1:100, and the ultrasonic dispersion time is 1-2 h.

[0020] As a further limited scheme of the preparation method of the application, in step 2, when the SS solution and the SF solution are added to the MXene nanosheet dispersion liquid, the mass parameter relationship of the MXene nanosheet dispersion liquid, the SS solution and the SF solution is 7:1:2; when mixed self-assembled, after stirring at room temperature for 4-5 h, ultrasonic for 1-2 h, the total solute concentration of the obtained MXene-SS / SF composite material is 10 mg / mL.

[0021] The application further provides an application of the MXene-SS / SF composite material as a sensing humidity layer in physical detection.

[0022] Compared with the prior art, the MXene-SS / SF composite material has the beneficial effects that: the MXene-SS / SF composite material is a few nanometer thick layered 2D material tightly packaged by a biopolymer nanoscale coating, and the composite film has a continuous electron transmission channel, a higher porosity and a larger specific surface area under the support of structural proteins, and the functional groups existing on the surface endow it with more active sites, so that it has significant conductivity and good hydrophilicity; in addition, the silk fibroin encapsulated MXene nanosheet shows nanofibril edges around the sheet layer, and has better oxidation stability than pure MXene; the sensor constructed by the MXene-SS / SF composite material has high sensitivity and wide detection limit in the detection of humidity, and has excellent response and recovery performance in the detection of humidity, so it has great application potential in the field requiring rapid detection of humidity. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 is a scanning electron microscope image of the MXene-SS / SF composite material of the application;

[0024] Figure 2 is a scanning electron microscope cross-sectional image of the MXene-SS / SF composite material of the application;

[0025] Figure 3 is an X-ray energy spectrum of the MXene-SS / SF composite material of the application; wherein, is O element, Ti element, N element, C element;

[0026] Figure 4 is a continuous dynamic humidity response of the modified LIG sensor of the MXene-SS / SF composite material with different mass ratios of the application to 6% RH;

[0027] Figure 5 is a continuous dynamic humidity response of the humidity sensor modified by the MXene-SS / SF (1:2) composite material of the application in the range of 6% to 98% relative humidity;

[0028] Figure 6It is a real-time hysteresis characteristic curve of a humidity sensor modified by the MXene-SS / SF (1:2) composite material of the present application. DETAILED DESCRIPTION

[0029] The technical solutions of the present application will be described in detail below with reference to the accompanying drawings, but the protection scope of the present application is not limited to the described embodiments.

[0030] As shown in Figure 1 The MXene-SS / SF composite material disclosed by the present application is a laminated nanocomposite film with continuous wrinkles distributed on the surface, the mass ratio of SS to SF in the MXene-SS / SF composite material is 1:2, MXene is a two-dimensional sheet-shaped nanomaterial, SS is silk sericin separated after alkalization of silk, SF is silk fibroin, and the composition structure of MXene is Ti3C2T x .

[0031] As a further limited scheme of the composite material of the present application, the thickness of the MXene-SS / SF composite material is less than 10 nm.

[0032] As a further limited scheme of the composite material of the present application, the elements C, O, Ti, and N in the MXene-SS / SF composite material are distributed in the form of a sheet layer, i.e., nitrogen-containing silk fibroin is uniformly distributed with the MXene sheet layer, so that the MXene-SS / SF composite material exhibits a micro-morphology of a continuous and complete conductive network film, and the silk fibroin beta-fold secondary organization extends through the edge of the MXene nanosheet layer and forms a nanofibril long side around a single MXene sheet layer, thereby improving the oxidation stability.

[0033] The present application also provides a preparation method of a MXene-SS / SF composite material for preparing the MXene-SS / SF composite material, comprising the following steps:

[0034] Step 1, preparing a MXene nanosheet dispersion liquid;

[0035] Step 2, adding SS solution and SF solution to the MXene nanosheet dispersion liquid to obtain a two-dimensional layered MXene-SS / SF composite material through mixing self-assembly.

[0036] As a further limited scheme of the preparation method of the present application, in step 1, the specific steps for preparing the MXene nanosheet dispersion liquid are as follows:

[0037] Step 1.1, uniformly mixing titanium aluminum carbide and lithium fluoride at a set mass ratio;

[0038] Step 1.2, after uniform mixing, adding to hydrochloric acid in a reaction kettle and etching at high temperature in a hydrochloric acid environment;

[0039] Step 1.3, MXene nanosheets were obtained after washing and centrifugation;

[0040] Step 1.4, MXene nanosheets were ultrasonically dispersed in ultrapure water to obtain a MXene nanosheet dispersion, for example, 35 mg of MXene nanosheets were ultrasonically dispersed in 5 ml of ultrapure water.

[0041] As a further limited scheme of the preparation method of the application, in step 1.1, the mass ratio of titanium aluminum carbide and lithium fluoride is 1:1.6.

[0042] As a further limited scheme of the preparation method of the application, in step 1.2, the concentration of hydrochloric acid is 12 mol / L, the etching time is 12-24 h, the optimal time is 24 h, the heating temperature in the reaction kettle is 40-50℃, the optimal etching temperature is 42℃, the stirring speed is 450-550 r / min, and the preferred stirring speed is 500 r / min.

[0043] As a further limited scheme of the preparation method of the application, in step 1.3, when washing, dilute hydrochloric acid is washed 2-4 times and deionized water is washed 5-7 times until the pH is neutral; when centrifuging, ultrasonic for 1 h under ice water bath condition, then centrifuging at a speed of 3500 r / min for 1 h.

[0044] As a further limited scheme of the preparation method of the application, in step 1.4, the mass ratio of MXene nanosheets to ultrapure water is 1:100, and the ultrasonic dispersion time is 1-2 h, and the ultrasonic effect is better for 2 h.

[0045] As a further limited scheme of the preparation method of the application, in step 2, when adding SS solution and SF solution to the MXene nanosheet dispersion, the mass parameter relationship of MXene nanosheet dispersion, SS solution and SF solution is 7:1:2; when mixing self-assembling, stirring for 4-5 h at room temperature, then ultrasonic for 1-2 h, preferably stirring for 5 h and then ultrasonic for 2 h, to obtain MXene-SS / SF composite material with a total solute concentration of 10 mg / mL.

[0046] The application also provides application of the MXene-SS / SF composite material as a sensing humidity layer in physical detection. The sericin (SS) forms a green adhesive and a dispersant through strong non-covalent interaction, the secondary structure of the silk fibroin (SF) has a humidity-sensitive structural change, and the MXene nanosheet layer is intercalated and controlled as an interlayer regulator of the MXene nanosheet, so that the MXene nanosheet has a continuous electron transmission channel, a higher porosity and a larger specific surface area under the support of the fiber, has the advantages of high conductivity and good mechanical flexibility, and therefore can be applied as a sensing humidity layer in physical detection. For example, a flexible humidity sensor is developed on a polyimide (PI) substrate by taking the MXene-SS / SF composite material as a humidity-sensitive material and taking laser-induced graphene (LIG) as a bottom electrode. In different relative humidity conditions (RH 6%~97%), the sensing performance of the humidity sensor is tested by adopting an amperometric i-t curve (i-t) method at a voltage of 1V, and the change relationship between the current of the sensing system and time under different RH environmental conditions is recorded.

[0047] When the MXene-SS / SF composite material is used to make a sensor, a CO2 laser is used to pattern and directly prepare a graphene electrode on a polyimide (PI) film in an air environment by using optimal laser parameter configurations of a power of 17W and a scanning speed of 130mm / s, 100μL of the prepared MXene-SS / SF composite material with six different mass ratios is respectively taken out by a pipette gun and uniformly dropped on the surface of the LIG interdigital electrode, and the humidity sensor is obtained by drying at room temperature to remove the solvent.

[0048] Example 1

[0049] When the MXene-SS / SF composite material with different proportions is prepared:

[0050] First, a nanomaterial MXene is synthesized by using a fluorine-containing molten salt etching method;

[0051] 1.6g of lithium fluoride and 1g of titanium aluminum carbide are added into 20ml of 12mol of concentrated hydrochloric acid, the etching time is 24h, the heating temperature in the reaction kettle is 42℃, and the stirring speed is 500r / min, and then MXene nanosheets are obtained after washing and centrifugal treatment;

[0052] 210mg of MXene nanosheets are ultrasonically dispersed in 30mL of water, and are divided into 6 equal parts for the next step, an SS-SF solution with a mass ratio of SS to SF of a:b (3:1, 2:1, 1:1, 0:1, 1:0 and 1:3) is configured, and the SS-SF solution with different mass ratios is respectively added into each equal part of the MXene nanosheet dispersion;

[0053] Finally, the MXene-SS / SF composite material with a total solute concentration of 10 mg / mL was obtained by stirring for 5 h at room temperature and then ultrasonicating for 2 h.

[0054] When the MXene-SS / SF composite material is used to construct a humidity sensor, the following steps are performed:

[0055] First, the graphene electrode is prepared by patterning direct writing on a polyimide (PI) film using a CO2 laser in an air environment, with an optimal laser parameter configuration of a power of 17 W and a scanning speed of 130 mm / s;

[0056] Then, 100 μL of each of the six MXene-SS / SF composite materials with different mass ratios prepared is uniformly dropped on the surface of the LIG interdigital electrode, and the six different humidity sensors are obtained by drying at room temperature to remove the solvent.

[0057] Example 2

[0058] When the MXene-SS / SF (1:2) composite material is prepared, the following steps are performed:

[0059] First, the nanomaterial MXene is synthesized by a fluorine-containing molten salt etching method;

[0060] 1.6 g of lithium fluoride and 1 g of titanium aluminum carbide are added to 20 ml of 12 mol of concentrated hydrochloric acid, and the etching time is 24 h; the heating temperature in the reaction kettle is 42℃, and the stirring speed is 500 r / min; after washing and centrifugal processing, the MXene nanosheet is obtained;

[0061] Then, 35 mg of MXene nanosheets are ultrasonically dispersed in 5 mL of water to prepare a MXene nanosheet dispersion liquid, and an SS-SF solution with a mass ratio of SS to SF of 1:2 is prepared; the SS-SF solution with a mass ratio of 1:2 is added to the MXene nanosheet dispersion liquid, and the MXene-SS / SF composite material with a total solute concentration of 10 mg / mL is obtained by stirring for 5 h at room temperature and then ultrasonicating for 2 h, as shown in Figure 1 、 Figure 2 and Figure 3 .

[0062] From Figure 1 and Figure 2It can be seen that the biopolymer nanoscale coating tightly encapsulates a few nanometer thick layered 2D material with humidity sensitive structural changes of SF secondary structure can be used as a regulator between MXene nanosheet layers, and SS is used as a green adhesive and dispersant through strong non-covalent interaction. The composite film has a continuous electron transport channel, higher porosity and larger specific surface area under the support of structural proteins, and the functional groups present on the surface endow it with more active sites, thereby having significant conductivity, good hydrophilicity. In addition, the silk protein encapsulated MXene nanosheet shows nanofibrillar edges around the sheet layer, which has better oxidation stability. Figure 3 The EDS spectrum of the MXene-SS / SF(1:2) composite material is shown in the figure, and the elements C, O, Ti and N are distributed in the form of sheet layer, which further confirms that SS and SF are "soft armor" covering the surface of MXene, forming a complete and continuous conductive network. Therefore, it can be proved that the MXene-SS / SF composite material is successfully prepared.

[0063] When constructing the MXene-SS / SF(1:2) humidity sensor:

[0064] In an air environment, a CO2 laser was used to pattern direct-write graphene electrodes on a polyimide (PI) film using the optimal laser parameter configuration of a power of 17 W and a scanning speed of 130 mm / s;

[0065] Then 100 μL of the prepared MXene-SS / SF composite material with a mass ratio of SS:SF = 1:2 was uniformly dropped on the surface of the LIG interdigital electrode, and dried at room temperature to remove the solvent to obtain a humidity sensor.

[0066] Example 3

[0067] When the MXene-SS / SF composite material with different mass ratios obtained according to the method of example 1 and example 2 is used as a humidity sensitive material:

[0068] A humidity sensor based on composite humidity sensitive layer was prepared by using polyimide (PI) film as flexible substrate, laser-induced graphene (LIG) as bottom electrode prepared by using the optimal laser parameters of power 17 W and scanning speed 130 mm / s. Various saturated salt solutions were prepared as saturated salt standard humidity source, including LiBr, LiCl, MgCl2, NaBr, NaCl, KCl and K2SO4. The sensor was exposed to the above different saturated salt solution environment. The response-recovery performance test of each sensor was carried out under different relative humidity (RH 6%~97%) conditions by adopting amperometric i-t curve (i-t) method, applying 1V constant working voltage, recording the change relationship of current of the sensing system with time under different RH environment conditions, and evaluating the humidity sensitivity of each composite film.

[0069] As shown in Figure 4 , it can be seen that under the same relative humidity conditions, compared with other mass ratio composite materials, the MXene-SS / SF composite material with mass ratio of 1:2 of SS and SF shows higher sensitivity.

[0070] Example 4

[0071] The MXene-SS / SF (1:2) humidity sensitive material obtained according to the method of Example 3 was used as the sensor humidity sensitive layer, a humidity sensor based on composite humidity sensitive layer was prepared by using polyimide (PI) film as flexible substrate, laser-induced graphene (LIG) as bottom electrode prepared by using the optimal laser parameters of power 17 W and scanning speed 130 mm / s; various saturated salt solutions were prepared as saturated salt standard humidity source, including LiBr, LiCl, MgCl2, NaBr, NaCl, KCl and K2SO4; the sensor was exposed to the above different saturated salt solution environment, continuous dynamic humidity response test was carried out by adopting amperometric i-t curve (i-t) method, applying 1V constant working voltage, and the RH value changed from 6% to 98%. The performance of MXene-SS / SF (1:2) humidity sensitive sensing material for humidity monitoring was embodied by detecting the change of current response with humidity, and the change of current response with relative humidity was as shown in Figure 5 , the humidity hysteresis curve of the sensor under the condition of MXene-SS / SF (1:2) was as shown in Figure 6 .

[0072] As shown in Figure 5 , the current intensity decreased with the increase of relative humidity, and had good repeatability. As shown in Figure 6It can be found that the linear fitting of the obtained wet hysteresis curve can find that there is a good linear relationship between the response current and the relative humidity condition, and through calculation, it is found that the sensor realizes low hysteresis, and the hysteresis is less than 3.7%RH, and the large hysteresis mainly occurs at 23%RH.

[0073] As can be known from the above, the MXene-SS / SF composite material synthesized by the present application with the mass ratio of SS to SF being 1:2 has high sensitivity, wide detection limit and good stability as a humidity detection sensor, and has excellent performance in humidity detection, so it has great application potential in the field requiring rapid response to humidity.

[0074] As described above, although the present application has been shown and described with reference to specific preferred embodiments, it is to be understood that such is by way of illustration and not of limitation. Various substitutions and changes can be made without departing from the spirit and scope of the present application as defined in the appended claims.

Claims

1. A MXene-SS / SF composite material, characterized in that, The MXene-SS / SF composite material is a laminated nanocomposite film with continuous wrinkle distributed on the surface, and the mass ratio of SS to SF in the MXene-SS / SF composite material is 1:

2. The MXene-SS / SF composite material is prepared by the following steps: Step 1, preparing a MXene nanosheet dispersion liquid; Step 2, adding SS solution and SF solution to the MXene nanosheet dispersion liquid to obtain a two-dimensional layered MXene-SS / SF composite material by mixing self-assembly.

2. The MXene-SS / SF composite material of claim 1, wherein, The thickness of the MXene-SS / SF composite material is less than 10 nm.

3. The MXene-SS / SF composite material of claim 1, wherein, The nitrogen-containing silk fibroin in the MXene-SS / SF composite material is uniformly distributed with the MXene sheet layer, and the silk fibroin beta-fold secondary organization extends through the edge of the MXene sheet layer and forms a nanofibril long edge around the single MXene sheet layer.

4. The MXene-SS / SF composite material of claim 1, wherein, In step 1, the specific steps for preparing the MXene nanosheet dispersion liquid are as follows: Step 1.1, uniformly mixing titanium aluminum carbide and lithium fluoride according to a set mass ratio; Step 1.2, after uniform mixing, adding to hydrochloric acid in a reaction kettle and etching at high temperature in a hydrochloric acid environment; Step 1.3, obtaining MXene nanosheets after washing and centrifugal processing; Step 1.4, ultrasonic dispersion of the MXene nanosheets in ultrapure water to obtain a MXene nanosheet dispersion liquid.

5. The MXene-SS / SF composite material of claim 4, wherein, In step 1.1, the mass ratio of titanium aluminum carbide to lithium fluoride is 1:1.

6.

6. The MXene-SS / SF composite material of claim 4, wherein, In step 1.2, the concentration of hydrochloric acid is 12 mol / L, the etching time is 12-24 h, the heating temperature in the reaction kettle is 40-50℃, and the stirring speed is 450-550 r / min.

7. The MXene-SS / SF composite material of claim 1, wherein, In step 1.4, the mass ratio of MXene nanosheets to ultrapure water is 1:100, and the ultrasonic dispersion time is 1-2 h.

8. The MXene-SS / SF composite material of claim 1, wherein, In step 2, when adding the SS solution and the SF solution to the MXene nanosheet dispersion liquid, the mass parameter relationship of the MXene nanosheet dispersion liquid, the SS solution and the SF solution is 7:1:2; after stirring at room temperature for 4-5 h and ultrasonic for 1-2 h, the total solute concentration of the obtained MXene-SS / SF composite material is 10 mg / mL.

9. Application of the MXene-SS / SF composite material according to any one of claims 1-3 as a sensing humidity layer in physical detection.

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