Liquid metal microsphere modified MXene film and preparation method thereof

Abstract

The application belongs to the technical field of composite materials, and particularly relates to a liquid metal microsphere modified MXene film and a preparation method thereof. The MXene film with a MXene-LP-MXene sandwich structure is formed by introducing liquid metal microspheres, the surface microstructure of the MXene film is controlled by the liquid metal, the surface morphology and optical performance of the film are controlled based on the Hagen-Rubens relationship, the Rayleigh scattering and the Mie scattering principle. The application realizes the enhancement of infrared reflection while maintaining low visible light reflection characteristics, has stable product structure and simple preparation method, provides an ideal basis for efficient light-heat conversion, and has wide application prospects in the fields of infrared stealth, radiation cooling, optical camouflage, flexible strain sensors and electromagnetic interference shielding.

Description

Technical Field

[0001] This invention belongs to the field of composite material technology, specifically relating to a liquid metal microsphere modified MXene film and its preparation method. Background Technology

[0002] MXene (such as Ti3C2T) x Due to its high conductivity and rich surface chemical properties, MXene has shown great potential in electromagnetic shielding, sensing, and energy storage. However, pure MXene films typically exhibit a dense and flat two-dimensional structure, making it difficult to flexibly control their optical properties (such as reflection and scattering) in the visible-infrared band. Furthermore, they are prone to cracking due to internal stress during the drying process, which limits their application in photothermal conversion, flexible optoelectronic devices, and other fields.

[0003] It is known that infrared reflectance is directly proportional to electrical conductivity, and high infrared reflectance also leads to high visible light reflectance, while microstructure affects visible light absorption. Existing technologies involve constructing MXene structures with different morphologies by adding pore-forming agents or templates; however, these methods often result in a significant decrease in electrical conductivity and make it difficult to achieve precise and synergistic control from microscopic morphology to macroscopic optoelectronic properties. Therefore, developing a method that can simultaneously optimize the structural stability, conductivity, and broadband optical properties of MXene thin films is of great significance. Summary of the Invention

[0004] To address the aforementioned problems and shortcomings, and to solve the limitations of existing MXene films in the visible-infrared band due to performance control and processing technology, this invention provides a liquid metal microsphere-modified MXene film and its preparation method. By introducing liquid metal microspheres to form a sandwich structure MXene film, the surface morphology and optical properties of the film can be controlled, and the structure is stable and the preparation method is simple.

[0005] The technical solution of the present invention is as follows:

[0006] A liquid metal microsphere-modified MXene film, comprising two layers of MXene film and liquid metal microspheres;

[0007] The liquid metal microspheres are embedded between two MXene films. A multi-scale composite structure is formed by the liquid metal microspheres embedded in the MXene matrix. The surface of the MXene film exhibits highly shape-controllable micro / nano-protrusions induced by the centrally embedded liquid metal microspheres, with the protrusion height adjustable on the scale of several micrometers.

[0008] Furthermore, the liquid metal is one of gallium, indium, tin and their alloys, preferably a gallium-indium-tin alloy.

[0009] The method for preparing the above-mentioned liquid metal microsphere-modified MXene film includes the following steps:

[0010] Step 1: Liquid metal is treated with a hydrochloric acid dopamine solution under ice bath conditions to induce an oxidative polymerization reaction of dopamine under ultrasound, generating polydopamine PDA and depositing it on the surface of liquid metal microparticles, thus obtaining a suspension of liquid metal microspheres coated with polydopamine.

[0011] Step 2: Centrifuge the suspension obtained in Step 1 to remove the hydrochloric acid dopamine solvent and retain the precipitate. Add deionized water to the precipitate to disperse it and then centrifuge again. After centrifugation, take the supernatant to obtain the liquid metal microsphere dispersion LP.

[0012] Step 3: The LP solution obtained in Step 2 is stacked with the MXene dispersion in a predetermined volume ratio and position through vacuum filtration to form a wet film with a three-layer structure of MXene-LP-MXene; the height and shape of the MXene film surface are induced by the liquid metal microspheres by the predetermined volume ratio and position.

[0013] Step 4: Dry the wet film obtained in Step 3 completely at room temperature to obtain the MXene film modified with liquid metal microspheres.

[0014] Beneficial effects of the present invention

[0015] Adjustable morphology and performance: By adjusting the addition volume (e.g., 2 ml, 4 ml) and relative position of liquid metal microspheres, the surface morphology of the film can be transformed from relatively flat to undulating, thus realizing the control of the microstructure of the MXene film surface.

[0016] Excellent optical performance:

[0017] High infrared reflectivity: The composite film exhibits high reflectivity in the infrared band. This is due to the metallic reflective properties of liquid metal itself, which allows it to form a metal film between MXene layers, thereby increasing infrared reflectivity. Additionally, liquid metal particles can connect MXene sheets, significantly reducing interlayer contact resistance, improving conductivity, and enhancing infrared reflectivity.

[0018] Low visible light reflection: When the amount of liquid metal added is high, the micron-scale rough surface and protrusions formed cause strong diffuse reflection of visible light, and the reflectivity is significantly reduced.

[0019] Controllable conductivity: conductivity can be improved with low addition amount, while conductivity decreases with high addition amount due to the destruction of the conductive network caused by the agglomeration of liquid metal particles. This provides options for different application scenarios (high conductivity or high impedance).

[0020] Enhanced structural stability: Liquid metal microspheres, acting as spacers, effectively alleviated the shrinkage stress of MXene sheets during the drying process. Combined with an optimized drying process, high-quality films with large areas and no cracks were successfully prepared.

[0021] The method is simple and efficient: the process is simple, all steps can be completed in the aqueous phase and at room temperature, and it is easy to scale up production.

[0022] In summary, this invention introduces liquid metal microspheres to form an MXene-LP-MXene sandwich structure MXene thin film. By controlling the surface microstructure of the MXene film through liquid metal, and based on the Hagen-Rubens relation, Rayleigh scattering, and Mie scattering principles, the surface morphology and optical properties of the film can be controlled. This invention achieves enhanced infrared reflection while maintaining strong diffuse reflection characteristics. The product structure is stable, and the preparation method is simple. It provides an ideal foundation for efficient photothermal conversion and has broad application prospects in fields such as infrared stealth, radiation cooling, optical camouflage, flexible strain sensors, and electromagnetic interference shielding. Attached Figure Description

[0023] Figure 1 The images shown are cross-sectional SEM images (ac) of the films prepared in Examples 1-3, corresponding to liquid metal addition amounts of 0, 2, 4, and ml, respectively.

[0024] Figure 2 The images shown are surface morphology diagrams (ac) of the thin films prepared in Examples 1-3, corresponding to liquid metal addition amounts of 0, 2, 4, and ml, respectively.

[0025] Figure 3 The graph shows the surface bulge height (a) and width (b) of the films prepared in Examples 1-3, corresponding to liquid metal addition amounts of 0, 2, 4 ml, respectively.

[0026] Figure 4 The infrared reflectance spectrum (a), visible light reflectance spectrum (b), and electrical conductivity spectrum (c) of the thin films prepared in Examples 1-3 correspond to liquid metal addition amounts of 0, 2, 4, and ml, respectively. Detailed Implementation

[0027] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0028] A method for preparing a liquid metal microsphere-modified MXene film includes the following steps:

[0029] Step 1: Preparation and Coating of Liquid Metal Microspheres: 0.2g of liquid metal was mixed with 50ml of 1mg / ml dopamine hydrochloride solution and poured into a centrifuge tube. The mixture was then sonicated in an ice bath at 0-4°C for 60 minutes. Under sonication, dopamine underwent oxidative polymerization to generate polydopamine (PDA), which was deposited on the surface of the liquid metal microspheres, effectively inhibiting the oxidative aggregation of LM. After sonication, a polydopamine-coated liquid metal suspension was obtained.

[0030] Step 2, Preparation of liquid metal microsphere dispersion LP: Centrifuge the suspension obtained in Step 1 (8500 rpm for 20 min), remove the dopamine hydrochloride solvent after centrifugation and retain the precipitate, then add 20 ml of deionized water to the precipitate, shake the centrifuge tube to disperse the precipitate in the deionized water and centrifuge (3500 rpm for 20 min), take the supernatant after centrifugation to obtain the LP solution, and the concentration of the LP solution was measured to be 0.25 mg / ml.

[0031] Step 3, Filtration and Film Formation: The LP solution obtained in Step 2 is stacked layer by layer with 12 mg / ml MXene dispersion at a specific volume ratio through vacuum filtration to form a wet film with an MXene-LP-MXene three-layer structure. The volumes of LP solution added are 0 ml, 2 ml, and 4 ml, respectively, and the volume of each of the two MXene dispersion layers is 1 ml.

[0032] Step 4, Drying: The wet film obtained in step 3 is dried completely at room temperature to obtain the MXene film modified with liquid metal microspheres.

[0033] like Figure 1 Figure ac shows cross-sectional SEM images of the films with added LM amounts of 0 ml, 2 ml, and 4 ml, respectively, in Examples 1-3. As the amount of added LM increases, the film formation becomes increasingly dense; and the overall undulation of the film becomes increasingly larger.

[0034] like Figure 2 Figures a and c show three-dimensional images of the surface morphology of films with added LM amounts of 0 ml, 2 ml, and 4 ml, respectively, in Examples 1-3. In figure a, the microstructure of the film surface is mainly composed of relatively large protrusions (red and yellow areas), which are sparsely distributed; in figure b, smaller local protrusions (yellow and green areas) begin to appear, the area of ​​the original large protrusions decreases, and large and small protrusions coexist and are more densely distributed; in figure c, the number of surface protrusions increases significantly, the surface undulations intensify, and obvious orange areas appear, representing an increase in higher areas and a greater difference in height.

[0035] Figure 3 a is a graph showing the average height of the surface bulges in Examples 1-3. Figure 3Figure b shows the average width of the surface bulges in Examples 1-3. Example 3 has the largest average bulge height and the smallest average bulge width, indicating that the bulges formed on the film surface are steeper. This structure effectively increases the light reflection path, dividing the single reflection path into multi-directional channels and reducing the energy concentration of the reflected light.

[0036] Figure 4 a is the full infrared reflectance spectrum of Examples 1-3. Figure 4 Figure b shows the full visible light reflectance spectrum of Examples 1-3, and Figure c shows the conductivity of Examples 1-3. The conductivity of Example 3 decreased, but the infrared reflectance did not, indicating that the metal film formed by LM between the MXene layers further enhanced the infrared reflectance. The decrease in visible light reflectance in Example 3, combined with its morphology and protrusion height, suggests the formation of many steep protrusions on the film surface, which increases the number of reflections of visible light. Furthermore, the large amount of liquid metal particles added, with more particles existing between the MXene layers, constitutes more scattering centers, increasing the scattering of visible light.

[0037] As can be seen from the above embodiments, this invention, based on the Hagen-Rubens relation, Rayleigh scattering, and Mie scattering principles, achieves enhanced infrared reflection while maintaining low visible light reflectance by controlling the surface microstructure of the MXene thin film with liquid metal. This provides an ideal foundation for efficient photothermal conversion. The composite thin film prepared by this invention has broad application prospects in fields such as infrared stealth, radiation cooling, optical camouflage, flexible strain sensors, and electromagnetic interference shielding.

Claims

1. A liquid metal microsphere-modified MXene film, characterized in that: It includes two layers of MXene film and liquid metal microspheres; The liquid metal microspheres are embedded between two MXene films, and the embedded liquid metal microspheres induce the formation of highly shape-controllable micro-nano bulges on the surface of the MXene films, with the bulge height on the scale of several micrometers.

2. The MXene film modified with liquid metal microspheres as described in claim 1, characterized in that: The liquid metal is one of gallium, indium, tin, and their alloys.

3. The MXene film modified with liquid metal microspheres as described in claim 2, characterized in that: The liquid metal is a gallium indium tin alloy.

4. The method for preparing MXene films modified with liquid metal microspheres as described in any one of claims 1-3, characterized in that, Includes the following steps: Step 1: Liquid metal is treated with hydrochloric acid dopamine solution under ice bath conditions to induce an oxidative polymerization reaction of dopamine under ultrasonic action, generating polydopamine PDA and depositing it on the surface of liquid metal microparticles, thus obtaining a suspension of liquid metal microspheres coated with polydopamine. Step 2: Centrifuge the suspension obtained in Step 1 to remove the hydrochloric acid dopamine solvent and retain the precipitate. Then add deionized water to the precipitate to disperse it and centrifuge again. After centrifugation, take the supernatant to obtain the liquid metal microsphere dispersion LP. Step 3: The LP solution obtained in Step 2 is stacked layer by layer with the MXene dispersion according to a preset volume ratio and position to form a wet film with a three-layer structure of MXene-LP-MXene by vacuum filtration; the height and shape of the MXene film surface are induced by liquid metal microspheres by the preset volume ratio and position. Step 4: Dry the wet film obtained in Step 3 completely at room temperature to obtain the MXene film modified with liquid metal microspheres.

5. The method for preparing the MXene thin film modified with liquid metal microspheres as described in claim 4, characterized in that, The specific process of step 1 is as follows: liquid metal is mixed with dopamine hydrochloride solution and poured into a centrifuge tube, and ultrasonic treatment is performed under ice bath conditions; wherein, the ice bath temperature is controlled at 0-4°C and the ultrasonic time is 60 minutes.

Images