A high-performance composite thermoelectric film and its preparation method and application

Abstract

This invention belongs to the field of inorganic thermoelectric composite thin film preparation technology, and discloses a high-performance composite thermoelectric thin film, its preparation method, and its application. First, Mo2TiAlC2 is treated using a chemical etching method; then, Ag2Te nanowires are synthesized using a hydrothermal method; finally, the Ag2Te nanowire solution is reacted with Mo2TiC2... X The Mxene material solution was mixed, wherein Mo2TiC2T X The mass of Mxene material accounts for a significant portion of Mo2TiC2T. X The mixture consists of 60% Mxene material and Ag2Te nanowires by mass. A vacuum filtration layer self-assembly method is then used to trap solid particles in the mixed solution onto the filter membrane using the negative pressure generated by the vacuum pump, resulting in a composite thermoelectric thin film with the best thermoelectric performance and a significantly improved Seebeck coefficient. The high thermoelectric performance of the prepared film is of great importance for wearable thermoelectric devices.

Description

Technical Field

[0001] This invention belongs to the field of inorganic thermoelectric composite film preparation technology, specifically relating to a high-performance composite thermoelectric film, its preparation method, and its application. Background Technology

[0002] High-performance thermoelectric materials have potential applications in self-powered wearable electronic products. Thermoelectric materials can directly convert heat energy into electrical energy and have unique advantages. Therefore, people are eager to develop more efficient and flexible thermoelectric materials. MAX compounds can be used to obtain a large number of MXene materials with special properties through chemical etching. Due to their mechanical flexibility, they can be applied to thermoelectric devices. However, existing thermoelectric devices based on MXene materials exhibit low Seebeck coefficients and power factors, that is, their thermoelectric performance is not high. Therefore, it is urgent to study thermoelectric thin films based on MXene materials. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and to propose a high-performance composite thermoelectric thin film, its preparation method, and its application.

[0004] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0005] In a first aspect, the present invention provides a method for preparing a high-performance composite thermoelectric thin film, the method comprising the following steps:

[0006] Step 1: Mo2TiAlC2 is treated with chemical etching to prepare a Mo2TiC2TX Mxene material solution;

[0007] Step 2: Ag2Te nanowires were synthesized using a hydrothermal method;

[0008] Step 3: Dilute Ag₂Te nanowires with water to obtain an Ag₂Te nanowire solution. Then, mix the Ag₂Te nanowire solution with a Mo₂TiC₂TX Mxene material solution, wherein the mass of Mo₂TiC₂TX Mxene material accounts for 60% of the total mass of Mo₂TiC₂TX Mxene material and Ag₂Te nanowires. Next, sonicate for 10-30 minutes, and then use a vacuum filtration layer self-assembly method. Utilizing the negative pressure generated by a vacuum pump, the solid particles in the mixed solution are trapped on the filter membrane, and then peeled off from the filter membrane to obtain a composite material.

[0009] Preferably, step 1 specifically comprises:

[0010] First, weigh 30 mL of 40% hydrofluoric acid solution and pour it into a polytetrafluoroethylene container. Slowly add 1 g of Mo2TiAlC2 to the hydrofluoric acid solution in batches. After reacting in an oil bath at 55°C for 72 h, an MXene solution is obtained. Then, centrifuge the MXene solution at 5000 rpm for 5 min, discard the supernatant, add ultrapure water to dissolve the precipitate, centrifuge and wash to make the solution pH 7. Next, add 4 mL of LTABAOH solution to the solution and sonicate for 5 min and then shake by hand for 20 min to obtain the Mo2TiC2TX MXene material solution.

[0011] Preferably, step 2 specifically includes:

[0012] Step 2.1: Add 1.44g tellurium dioxide, 0.8g polyvinylpyrrolidone, and 1.46g sodium hydroxide to 70mL ethylene glycol and stir continuously at room temperature for 6h until the solution is clear; then heat the mixed solution at 160℃ for 24h and cool to room temperature, add 70mL anhydrous ethanol and stir evenly, then centrifuge at 8500rpm / min to synthesize tellurium nanowires, and add ethylene glycol to prepare a 0.01g / ml tellurium nanowire solution;

[0013] Step 2.2: React 5g of silver nitrate solid with 50ml of ethylene glycol and stir for 10min at room temperature to prepare a 0.1g / ml silver nitrate solution;

[0014] Step 2.3: Mix 0.01 g / ml tellurium nanowire solution and 0.1 g / ml silver nitrate solution at a volume ratio of 1:2.5, and then wash with anhydrous ethanol at a speed of 8500 rpm / min to obtain silver telluride nanowires.

[0015] Secondly, the present invention provides a high-performance composite thermoelectric thin film, which is prepared using the aforementioned preparation method.

[0016] Thirdly, the present invention provides the application of the high-performance composite thermoelectric thin film in thermoelectric devices.

[0017] The present invention has the following beneficial effects: The present invention proposes to transform Mo2TiC2T X MXene is mixed with Ag2Te nanowires, and when Mo2TiC2T X Mxene accounts for a significant portion of the Mo2TiC2T mass. X The film obtained with 60% of the total mass of Mo2TiC2T nanowires exhibited the best thermoelectric properties, with a significantly improved Seebeck coefficient. This is attributed to the phase transition or structural changes that Ag2Te undergoes during the mixing process, which optimize its thermoelectric performance. Meanwhile, the Mo2TiC2T... xThe presence of Ag2Te acts as a template or catalyst, promoting the formation of microstructures that are more conducive to thermoelectric conversion. Therefore, this material is expected to drive the development and application of thermoelectric technology. The high thermoelectric performance of the prepared film plays an important role in wearable thermoelectric devices, ensuring the durability and stability of thermoelectric devices.

[0018] In addition, the silver telluride nanowires prepared by the present invention using tellurium nanowire solution and silver nitrate solution at a volume ratio of 1:2.5 have advantages such as high aspect ratio, controllable diameter, relatively smooth surface and good mechanical properties, which ensure that the prepared thin film material has beneficial thermoelectric properties. The preparation process is simple and low cost. Attached Figure Description

[0019] Figure 1 SEM image (10 μm) of silver telluride nanowires with a tellurium nanowire solution to silver nitrate solution volume ratio of 1:0.5;

[0020] Figure 2 SEM image (5 μm) of silver telluride nanowires with a tellurium nanowire solution to silver nitrate solution volume ratio of 1:0.5;

[0021] Figure 3 SEM image (3 μm) of silver telluride nanowires with a tellurium nanowire solution to silver nitrate solution volume ratio of 1:1.5;

[0022] Figure 4 SEM image (2 μm) of silver telluride nanowires with a tellurium nanowire solution to silver nitrate solution volume ratio of 1:1.5.

[0023] Figure 5 SEM image (4 μm) of silver telluride nanowires with a tellurium nanowire solution to silver nitrate solution volume ratio of 1:2.5.

[0024] Figure 6 SEM image (2 μm) of silver telluride nanowires with a tellurium nanowire solution to silver nitrate solution volume ratio of 1:2.5.

[0025] Figure 7 SEM image (1 μm) of silver telluride nanowires with a tellurium nanowire solution to silver nitrate solution volume ratio of 1:2.5.

[0026] Figure 8 SEM image (4 μm) of Mo2TiAlC2;

[0027] Figure 9 To prepare Mo2TiC2T X SEM image (2 μm) of the cross-section of Mxene material;

[0028] Figure 10SEM image (10 μm) of the composite film prepared in Example 1;

[0029] Figure 11 SEM image (20 μm) of the composite film prepared in Example 1;

[0030] Figure 12 XRD pattern of Ag2Te nanowires prepared in Example 1;

[0031] Figure 13 The XRD pattern of the composite film prepared in Example 1;

[0032] Figure 14 A photograph of the composite device fabricated from the composite thin film prepared in Example 1;

[0033] Figure 15 The voltage difference generated at different temperatures in the composite device prepared from the composite thin film of Example 1;

[0034] Figure 16 The open-circuit voltage of the composite device prepared from the composite thin film of Example 1 at different temperature gradients;

[0035] Figure 17 The current-voltage curve and output power of the composite device prepared from the composite thin film prepared in Example 1;

[0036] Figure 18 Comparison of Seebeck coefficients for different composite materials;

[0037] Figure 19 Comparison of power factors of different composite materials;

[0038] Figure 20 This is a photograph of the composite material after vacuum filtration. Detailed Implementation

[0039] The present invention will be further described below with reference to embodiments, but these embodiments are not intended to limit the scope of the invention.

[0040] Study on the preparation of Ag2Te nanowires

[0041] First, 1.44 g of tellurium dioxide, 0.8 g of polyvinylpyrrolidone, and 1.46 g of sodium hydroxide were added to 70 mL of ethylene glycol, and the mixture was stirred continuously at room temperature for 6 hours until the solution became clear. Then, the mixture was added to a 100 mL hydrothermal reactor and heated at 160 °C for 24 hours, followed by cooling to room temperature. 70 mL of anhydrous ethanol was added to the reacted solution and stirred until homogeneous. The synthesized Te nanowires were then centrifuged at 8500 rpm / min. The Te nanowires were further washed three times with anhydrous ethanol to obtain the tellurium nanowires. Rice noodles were mixed with ethylene glycol to prepare a 0.01 g / ml tellurium nanowire solution. 5 g of solid silver nitrate was reacted with 50 ml of ethylene glycol and stirred at room temperature for 10 min to prepare a 0.1 g / ml silver nitrate solution. The 0.01 g / ml tellurium nanowire solution and the 0.1 g / ml silver nitrate solution were then mixed, and the Ag₂Te nanowires were washed three times with anhydrous ethanol at 8500 rpm / min. This centrifugation-assisted method was used to exfoliate the silver telluride nanowires, yielding high aspect ratio silver telluride nanowires. The resulting black solid was dried in a 60°C oven for 25 min, then water was added, followed by sonication for 15 min to prepare an aqueous solution of silver telluride nanowires, which was then stored at -20°C for later use.

[0042] Different volume ratios of tellurium nanowire solution and silver nitrate solution were studied: (1) The volume ratio of tellurium nanowire solution to silver nitrate solution was 1:0.5, such as... Figure 1-2 As shown;

[0043] (2) The tellurium nanowire solution and silver nitrate solution are mixed in a volume ratio of 1:1.5, such as... Figure 3-4 As shown;

[0044] (3) The tellurium nanowire solution and silver nitrate solution are mixed in a volume ratio of 1:2.5, such as... Figure 5-7 As shown;

[0045] As can be seen from the attached figure, silver telluride nanowires prepared by using tellurium nanowire solution and silver nitrate solution at a volume ratio of 1:2.5 have advantages such as high aspect ratio, controllable diameter, and relatively smooth surface.

[0046] Example 1

[0047] Preparation of Mo2TiC2T X Mxene material solution:

[0048] The MAX phase (Mo2TiAlC2) was treated using a chemical etching method. First, 30 mL of a 40% hydrofluoric acid solution was weighed and poured into a polytetrafluoroethylene (PTFE) container. Then, 1 g of the MAX phase material (Mo2TiAlC2) was weighed using an electronic balance and slowly added in batches to the HF solution. This was to prevent excessively rapid addition of the solution, which could lead to insufficient heat dissipation and solution splashing. HF selectively etched the "A" layer (aluminum, Al) in the MAX phase, as shown in the following reaction equation: 2Mo2TiAlC2 + 6HF → 2Mo2TiC2 + 2AlF3 + 3H2. During this process… Aluminum is replaced by fluoride to form soluble fluoroaluminate (AlF3) and release hydrogen gas. After reacting in an oil bath at 55℃ for 72 hours, an MXene solution is obtained. This time is set to ensure complete removal of the "A" layer without damaging the layered structure of Mo2TiC2, thus improving the thermoelectric properties of the prepared film. At this point, the solution is acidic. The solution is centrifuged at 5000 rpm for 5 minutes, the supernatant is discarded, and ultrapure water is added to dissolve the precipitate. This step is repeated 5 times until the solution pH is close to 7, yielding approximately 10 mL of a high-concentration solution. At this point, multilayered MXenes are obtained. 4 mL of TBAOH solution is then added to the solution for intercalation. The multilayered MXenes (HF etched powder) further react with TBAOH, inserting tetrabutylammonium cations (TBAOH) between the negatively charged MXene sheets. + This process caused the two-dimensional MXene sheets to detach. The resulting solution was then subjected to sonication for 5 minutes and hand-shaking for 20 minutes to completely detach the nanosheets.

[0049] Preparation of Ag₂Te nanowires (tellurium nanowire solution and silver nitrate solution were mixed at a volume ratio of 1:2.5):

[0050] First, 1.44 g of tellurium dioxide, 0.8 g of polyvinylpyrrolidone, and 1.46 g of sodium hydroxide were added to 70 mL of ethylene glycol and stirred continuously at 25 °C for 6 hours until the solution became clear. Then, the mixture was added to a 100 mL hydrothermal reactor and heated at 160 °C for 24 hours, followed by cooling to 25 °C. 70 mL of anhydrous ethanol was added to the reacted solution and stirred until homogeneous. The synthesized Te nanowires were then centrifuged at 8500 rpm / min. The Te nanowires were further washed three times with anhydrous ethanol. The resulting tellurium nanowires were then subjected to further treatment with ethanol. A 0.01 g / ml tellurium nanowire solution was prepared using glycol. 5 g of solid silver nitrate was reacted with 50 ml of ethylene glycol and stirred at room temperature for 10 min to prepare a 0.1 g / ml silver nitrate solution. The 0.01 g / ml tellurium nanowire solution and the 0.1 g / ml silver nitrate solution were then mixed at a volume ratio of 1:2.5. The Ag₂Te nanowires were further washed three times with anhydrous ethanol at 8500 rpm / min, effectively exfoliating the silver telluride nanowires using a centrifuge-assisted method, yielding high aspect ratio silver telluride nanowires. The resulting black solid was dried in a 60°C oven for 25 min, then water was added, followed by sonication for 15 min to prepare an aqueous solution of silver telluride nanowires, which was then stored at -20°C for later use.

[0051] Preparation of high-performance composite thermoelectric thin films:

[0052] Mo2TiC2T X Mxene material solution was mixed with Ag2Te nanowire solution, wherein Mo2TiC2T X The mass of Mxene material accounts for a significant portion of Mo2TiC2T. X The mixture consists of 60% Mxene material and Ag2Te nanowires by mass. After sonication for 10-30 minutes, a vacuum filtration layer self-assembly method is used. This method utilizes the negative pressure generated by a vacuum pump (0.098 MPa, flow rate 60 L / min) to trap solid particles or specific components from the mixed solution onto the filter membrane. These particles are then peeled off from the filter membrane to obtain a composite thermoelectric thin film. Figure 15 As shown, the greater the temperature difference over time, the higher the final voltage value, indicating that under higher temperature differences, the thermoelectric generator prepared in this embodiment can produce a better voltage and has better thermoelectric performance; as Figure 16 As shown, the output performance during this period was studied under different temperature gradients of 10-60K, indicating that the voltage can be further increased by increasing the temperature gradient to meet practical requirements; for example... Figure 17As shown, the voltage and power output curves of the composite material device are displayed, which depend on the load current when ΔT is 30K. It can be observed that when the voltage output is 7.1mV and the load current is 89nA, the maximum power density is 0.32μWm-2, and the external resistance is 79kΩ.

[0053] Comparative Example 1

[0054] The difference compared to Example 1 is as follows:

[0055] Mo2TiC2T X Mxene material solution was mixed with Ag2Te nanowire solution, wherein Mo2TiC2T X The mass of Mxene material accounts for a significant portion of Mo2TiC2T. X The total mass of Mxene material and Ag2Te nanowires is 20%. Then, the mixture is sonicated for 10-30 minutes. The vacuum filtration layer self-assembly method is then used to use the negative pressure generated by the vacuum pump to trap solid particles or specific components in the mixed solution on the filter membrane, thus obtaining a composite thermoelectric thin film.

[0056] Comparative Example 2

[0057] The difference compared to Example 1 is as follows:

[0058] Mo2TiC2T X Mxene material solution was mixed with Ag2Te nanowire solution, wherein Mo2TiC2T X The mass of Mxene material accounts for a significant portion of Mo2TiC2T. X The mixture consists of 40% of the total mass of Mxene material and Ag2Te nanowires. After sonication for 10-30 minutes, a vacuum filtration layer self-assembly method is used to retain solid particles or specific components in the mixed solution on the filter membrane using the negative pressure generated by the vacuum pump, thus obtaining a composite thermoelectric thin film.

[0059] Comparative Example 3

[0060] The difference compared to Example 1 is as follows:

[0061] Mo2TiC2T X Mxene material solution was mixed with Ag2Te nanowire solution, wherein Mo2TiC2T X The mass of Mxene material accounts for a significant portion of Mo2TiC2T. X The mixture consists of 80% of the total mass of Mxene material and Ag2Te nanowires. Then, it is sonicated for 10-30 minutes. Finally, a vacuum filtration layer self-assembly method is used to retain solid particles or specific components in the mixed solution on the filter membrane by using the negative pressure generated by the vacuum pump, thus obtaining a composite thermoelectric thin film.

[0062] Comparative Example 4

[0063] The difference compared to Example 1 is as follows:

[0064] Mo2TiC2T X The Mxene material solution is obtained by using a vacuum filtration layer self-assembly method. The negative pressure generated by the vacuum pump is used to trap solid particles or specific components in the mixed solution on the filter membrane to obtain a composite thermoelectric film.

[0065] Mechanically supported thin films were obtained through a vacuum filtration layer self-assembly method. Figure 18 and Figure 19 The results show that when Mxene accounts for 60% of the total composition, it exhibits a high Seebeck coefficient and power factor, indicating optimal thermoelectric performance and superior thermoelectric properties. Further increasing the proportion of Mxene will lead to a decrease in the thermoelectric coefficient.

[0066] Fabrication of composite devices:

[0067] like Figure 14 As shown, the composite film prepared in Example 1 was cut into 6 groups of strips of uniform size and shape, and the device was encapsulated as a whole. The flexibility of the device allows it to adapt to the curved structure of the human body and maintain good contact and performance even when bent.

[0068] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. However, the above description is merely a specific embodiment of the present invention, and the technical features of the present invention are not limited thereto. Any other embodiments derived by those skilled in the art without departing from the technical solution of the present invention should be covered within the patent scope of the present invention.

Claims

1. A method for preparing a high-performance composite thermoelectric thin film, characterized in that, The method includes the following steps: Step 1: Mo2TiAlC2 is treated with chemical etching to prepare Mo2TiC2T. X Mxene material solution; Step 2: Ag2Te nanowires were synthesized using a hydrothermal method; Step 3: Dilute Ag2Te nanowires with water to obtain Ag2Te nanowire solution, then mix Ag2Te nanowire solution with Mo2TiC2T X The Mxene material solution was mixed, wherein Mo2TiC2T X The mass of Mxene material accounts for a significant portion of Mo2TiC2T. X The mixture consists of 60% of the total mass of Mxene material and Ag2Te nanowires. After sonication for 10-30 minutes, a vacuum filtration layer self-assembly method is used to trap solid particles in the mixed solution on the filter membrane using the negative pressure generated by the vacuum pump. The particles are then peeled off from the filter membrane to obtain a composite thermoelectric thin film.

2. The method for preparing the high-performance composite thermoelectric thin film according to claim 1, characterized in that, Step 1 specifically involves: First, weigh 30 mL of a 40% hydrofluoric acid solution and pour it into a polytetrafluoroethylene container. Slowly add 1 g of Mo₂TiAlC₂ to the hydrofluoric acid solution in batches. After reacting in an oil bath at 55°C for 72 h, an MXene solution is obtained. Then, centrifuge the MXene solution at 5000 rpm for 5 min, discard the supernatant, add ultrapure water to dissolve the precipitate, centrifuge and wash to adjust the pH to 7. Next, add 4 mL of TBAOH solution to the solution and sequentially sonicate for 5 min and then hand-shake for 20 min to obtain Mo₂TiAlC₂T. X Mxene material solution.

3. The method for preparing the high-performance composite thermoelectric thin film according to claim 1, characterized in that, Step 2 specifically involves: Step 2.1: Add 1.44g tellurium dioxide, 0.8g polyvinylpyrrolidone, and 1.46g sodium hydroxide to 70mL ethylene glycol and stir continuously at room temperature for 6h until the solution is clear; then heat the mixed solution at 160℃ for 24h and cool to room temperature, add 70mL anhydrous ethanol and stir evenly, then centrifuge at 8500rpm / min to synthesize tellurium nanowires, and add ethylene glycol to prepare a 0.01g / ml tellurium nanowire solution; Step 2.2: React 5g of silver nitrate solid with 50ml of ethylene glycol and stir for 10min at room temperature to prepare a 0.1g / ml silver nitrate solution; Step 2.3: Mix 0.01 g / ml tellurium nanowire solution and 0.1 g / ml silver nitrate solution at a volume ratio of 1:2.5, and then wash with anhydrous ethanol at a speed of 8500 rpm / min to obtain silver telluride nanowires.

4. A high-performance composite thermoelectric thin film, characterized in that, The thin film is prepared using the preparation method according to any one of claims 1-3.

5. The application of the high-performance composite thermoelectric thin film according to claim 4 in thermoelectric devices.

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