Ionic thermoelectric Fe-MWCNT thin film device and its preparation method and application

Abstract

The present invention discloses an ionic thermoelectric Fe-MWCNT thin film device, its preparation method, and application. The device comprises the following steps: covering a MWCNT film with an FeCl₃·6H₂O solution, extracting the film to obtain a Fe-MWCNT thin film, and placing an Fe-PAM gel in the middle of the Fe-MWCNT film to obtain an ionic thermoelectric Fe-MWCNT thin film device based on a field-effect transistor (FET) structure. The device utilizes inexpensive and readily available raw materials, has a simple structure, and is easy to manufacture. By combining the device with an additional Fe-PAM gel gate structure to form an effective FET structure, the device effectively amplifies the ionic thermoelectric effect of the Fe-MWCNT film, and increases the Seebeck coefficient by over 43%. This invention opens up a new approach to ionic thermoelectric research.

Description

Technical Field

[0001] The invention relates to an ionic thermoelectric Fe-MWCNT thin film device and a preparation method and application thereof, belonging to the field of thermoelectric materials. Background Art

[0002] The development of renewable energy sources (such as photovoltaics, biomass, and geothermal energy) has attracted widespread attention across numerous technological fields due to its low cost, environmental friendliness, and convenience. As an important green energy material, thermoelectric (TE) materials can directly convert thermal energy into electrical energy through the movement of charge carriers within solids. These devices can operate even under very limited temperature gradients, have no moving parts, are silent, and have a long service life. Generally speaking, thermoelectric materials can be divided into two categories: organic and inorganic. The development of inorganic TEs has a decades-long history, and several have been applied in novel batteries, refrigeration devices, microsensors, and other applications. However, disadvantages such as high cost, high toxicity, complex manufacturing processes, and scarce resources hinder their widespread application. Compared to inorganic TEs, organic TEs offer advantages such as a high Seebeck coefficient, low thermal conductivity, good flexibility, excellent processability, light weight, and low toxicity. They have become promising candidates for thermoelectric applications, and their research is of great significance.

[0003] The large amount of heat wasted due to industrial energy consumption has driven the development of thermoelectric power generation, which converts heat into electricity. However, the main challenge faced by thermoelectric devices in practical applications is the high cost of materials and manufacturing. In recent years, the rapid breakthrough of the ionic Seebeck effect from the electrolyte between two electrodes has provided new possibilities for charging energy storage devices under temperature gradients. Electrolytes with a high Seebeck coefficient (Seebeck: S) are generally classified as ionic thermoelectric materials. Most ionic thermoelectric materials have abundant and easily accessible elements and are cheaper than traditional thermoelectric materials. They can generate thermoelectric potentials hundreds of times greater than traditional bulk electronic materials. This emerging field has brought new hope for the manufacture of low-cost and large-area thermal energy conversion devices and has sparked research interest in ionic thermal diffusion.

[0004] Currently, there is little research on devices that utilize field-effect transistor (FET) structures to enhance the thermoelectric properties of simple ions (electron-hole pairs are typically studied in FET structures). Typically, the output voltage due to the thermoelectric effect is calculated using the formula ΔS = ΔV / ΔT, where ΔV is the voltage across the hot and cold ends of the material, and ΔT is the temperature difference between the hot and cold ends. By heating one end of the film, both voltage and temperature changes can be observed. Summary of the Invention

[0005] In view of the problems existing in the above-mentioned prior art, the present invention provides an ionic thermoelectric Fe-MWCNT thin film device and a preparation method and application thereof.

[0006] To achieve the above objectives, the present invention adopts a method for preparing an ionic thermoelectric Fe-MWCNT thin film device, comprising the following steps: covering a MWCNT film with a FeCl3·6H2O solution, extracting the film to obtain a Fe-MWCNT thin film, and placing an Fe-PAM gel in the middle of the Fe-MWCNT film to obtain an ionic thermoelectric Fe-MWCNT thin film device based on a field-effect transistor structure.

[0007] Preferably, the MWCNT membrane is prepared by mixing carbon nanotubes and sodium dodecylbenzenesulfonate in deionized water, ultrasonically mixing the mixture, and then vacuum filtering the mixture.

[0008] Preferably, after the vacuum filtration of the MWCNT membrane is completed, FeCl3·6H2O solution is poured onto the MWCNT membrane, and the membrane is vacuum-filtered again to obtain a Fe-MWCNT membrane, which is then dried at room temperature and cut.

[0009] Preferably, the Fe-PAM gel is prepared by soaking PAM gel in FeCl 3 · 6H 2 O.

[0010] Preferably, the PAM gel is prepared by mixing acrylamide, potassium persulfate and N,N-methylenebisacrylamide and then gelling them in a drying oven.

[0011] Preferably, the preparation method comprises the following steps:

[0012] (1) Preparation of PAM gel: 4-6 g of acrylamide was placed in a beaker containing 15-25 mL of deionized water and stirred magnetically until completely dissolved. 20-30 mg of potassium persulfate and 0.8-1.2 mg of N,N-methylenebisacrylamide were then added and stirred magnetically until completely dissolved to obtain a polyacrylamide solution. The polyacrylamide solution was transferred to a mold and dried in a drying oven at 55-65°C for 25-35 min to obtain a PAM gel.

[0013] (2) Preparation of Fe-PAM gel: 1.5-2.5 mL of 2.8-3.2 mol / L ferric chloride hexahydrate solution was taken, and the PAM gel prepared in step (1) was placed in the ferric chloride hexahydrate solution and soaked for 10-14 h to obtain Fe-PAM gel;

[0014] (3) Preparation of Fe-MWCNT film: 15-18 mg of multi-walled carbon nanotubes and 150-170 mg of sodium dodecylbenzenesulfonate were added to 25-35 mL of deionized water, ultrasonically crushed for 25-35 min, vacuum filtered with a nylon membrane filter, and then washed with deionized water. Then, 8-12 mL of ferric chloride hexahydrate solution was added, and vacuum filtered again for 1.5-2.5 h. After that, the Fe-MWCNT film was dried in a vacuum drying oven at 55-65 °C for 0.5-1.5 h.

[0015] (4) The Fe-MWCNT film is used as the thermoelectric layer, and the Fe-PAM gel is placed in the middle of the Fe-MWCNT film to obtain an ionic thermoelectric Fe-MWCNT film device.

[0016] As a further preferred embodiment, after the polyacrylamide solution is transferred to the mold in step (1), the mold is covered with plastic wrap.

[0017] As a further preference, in the step (3), ultrasonic pulverization is performed for 5 seconds every 10 seconds.

[0018] In addition, the present invention also provides an ionic thermoelectric Fe-MWCNT thin film device prepared by the method.

[0019] Finally, the present invention also provides an application of the ionic thermoelectric Fe-MWCNT thin film device in a thermal energy conversion device.

[0020] The principle of the present invention is: utilizing the field-effect tube structure and the high Seebeck coefficient of ionic thermoelectric materials, selecting Fe-MWCNT film as the thermoelectric layer, cutting the Fe-MWCNT film into 20 mm × 4 mm rectangular thermoelectric legs, and placing Fe-PAM gel in the middle of the film to obtain an ionic thermoelectric Fe-MWCNT film device based on the field-effect tube structure.

[0021] The raw materials of this device are cheap and easily available, and it has a simple structure and is easy to manufacture. By forming an effective field-effect transistor structure with an additional Fe-PAM gel gate structure, it can effectively amplify the ionic thermoelectric effect of the Fe-MWCNT film, and the Seebeck coefficient is increased by more than 43%. This invention has opened up a new approach to the research of ionic thermoelectricity. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 Schematic diagram of the preparation process of an embodiment of the present invention; Figure (a) is the preparation of Fe-MWCNT film, (b) is the preparation of Fe-PAM gel, and (c) is the preparation of ionic thermoelectric Fe-MWCNT thin film device;

[0023] Figure 2Ultra-high resolution scanning electron microscope images of Fe-MWCNT films prepared using ferric chloride hexahydrate solutions of different concentrations (0M, 4M, and 10M) in Examples 1, 2, and 3 of the present invention; Figure (a) is a MWCNT film, Figure (b) is a 4M Fe-MWCNT film, and Figure (c) is a 10M Fe-MWCNT film.

[0024] Figure 3 Schematic diagram of output voltage changes of the ionic thermoelectric Fe-MWCNT thin film devices of Examples 1, 2, and 3 and the Fe-MWCNT thin film of the comparative example. DETAILED DESCRIPTION

[0025] The following embodiments are further descriptions of the present invention to illustrate the technical content of the present invention, but the essential content of the present invention is not limited to the following embodiments. Ordinary technicians in this field can and should know that any simple changes or replacements based on the essential spirit of the present invention should fall within the scope of protection required by the present invention.

[0026] Example 1

[0027] like Figure 1 As shown, a method for preparing an ionic thermoelectric Fe-MWCNT thin film device includes the following steps:

[0028] (1) 5 g of acrylamide was weighed and placed in a beaker containing 20 mL of deionized water. The sample was stirred on a magnetic stirrer until it was completely dissolved. Then, 25 mg of potassium persulfate and 1 mg of N,N-methylenebisacrylamide were added and magnetic stirring was continued until it was completely dissolved. The prepared polyacrylamide (PAM) solution was transferred to a mold using a pipette, and the mold was covered with plastic wrap (to reduce the coagulation time). The mold was then dried in an electric blast drying oven at 60°C for 30 min to obtain a PAM gel.

[0029] (2) 16.2 g of ferric chloride hexahydrate was placed in a beaker containing 20 mL of deionized water and stirred on a magnetic stirrer until dissolved to obtain a 3 mol / L ferric chloride hexahydrate solution. 2 mL of ferric chloride hexahydrate solution was taken and the PAM gel prepared in step (1) was placed in the ferric chloride hexahydrate solution and soaked for 12 h to fully dissolve the Fe 3+ Dip into the gel to obtain Fe-PAM gel (take 10 portions of 2 mL of ferric chloride hexahydrate solution and soak the PAM gel respectively to obtain 10 portions of Fe-PAM gel for later use);

[0030] (3) 16 mg of multi-walled carbon nanotubes (MWCNTs) and 160 mg of sodium dodecylbenzenesulfonate were added to 30 mL of deionized water to obtain a mixture solution. The mixture solution was ultrasonicated for 30 min (5 s ultrasonication every 10 s), and then the pulverized solution was vacuum filtered through a nylon membrane filter (pore size of 0.22 μm, diameter of 47 mm). 5 mL of deionized water was poured into the membrane five times to wash away excess sodium dodecylbenzenesulfonate. After filtering for 2 h, the flexible MWCNT film was dried in a vacuum drying oven at 60° C. for 1 h to obtain a MWCNT film. In this step (3), 0 M ferric chloride hexahydrate solution was added;

[0031] (4) MWCNT film was selected as the thermoelectric layer, and the MWCNT film was cut into rectangular thermoelectric legs of 20 mm × 4 mm. Then, Fe-PAM gel was placed in the middle of the film. A carbon cloth was extended from the gel to connect the electrode at one end of the film to obtain a MWCNT film device based on a field effect tube structure.

[0032] Example 2

[0033] Steps (1) and (2) of this embodiment are the same as steps (1) and (2) in embodiment 1;

[0034] (3) 16 mg of multi-walled carbon nanotubes (MWCNTs) and 160 mg of sodium dodecylbenzenesulfonate were added to 30 mL of deionized water to obtain a mixture solution. The mixture solution was ultrasonicated for 30 min using a cell crusher (5 s ultrasonication every 10 s), and then the crushed solution was vacuum filtered through a nylon membrane filter (pore size 0.22 μm, diameter 47 mm). 5 mL of deionized water was poured into the membrane five times to wash away excess sodium dodecylbenzenesulfonate. Finally, 10 mL of 4 M ferric chloride hexahydrate solution was added and filtered for 2 h. The flexible Fe-MWCNT film was dried in a vacuum drying oven at 60 ° C for 1 h to obtain a Fe-MWCNT film.

[0035] (4) Fe-MWCNT film was selected as the thermoelectric layer, and the Fe-MWCNT film was cut into rectangular thermoelectric legs of 20 mm × 4 mm. Then Fe-PAM gel was placed in the middle of the film. A carbon cloth was extended from the gel to connect the electrode at one end of the film to obtain an ionic thermoelectric Fe-MWCNT film device based on a field-effect tube structure.

[0036] Example 3

[0037] Steps (1) and (2) of this embodiment are the same as steps (1) and (2) in embodiment 1;

[0038] (3) 16 mg of multi-walled carbon nanotubes (MWCNTs) and 160 mg of sodium dodecylbenzenesulfonate were added to 30 mL of deionized water to obtain a mixture solution. The mixture solution was ultrasonicated for 30 min (5 s ultrasonication every 10 s), and then the crushed solution was vacuum filtered through a nylon membrane filter (pore size 0.22 μm, diameter 47 mm). 5 mL of deionized water was poured into the membrane five times to wash away excess sodium dodecylbenzenesulfonate. Finally, 10 mL of 10 M ferric chloride hexahydrate solution was added and filtered for 2 h. The flexible Fe-MWCNT film was dried in a vacuum drying oven at 60 ° C for 1 h to obtain a Fe-MWCNT film.

[0039] (4) Fe-MWCNT film was selected as the thermoelectric layer, and the Fe-MWCNT film was cut into rectangular thermoelectric legs of 20 mm × 4 mm. Then Fe-PAM gel was placed in the middle of the film. A carbon cloth was extended from the gel to connect the electrode at one end of the film to obtain an ionic thermoelectric Fe-MWCNT film device based on a field-effect tube structure.

[0040] Ultra-high resolution scanning electron microscope images of Fe-MWCNT films prepared using ferric chloride hexahydrate solutions of different concentrations (0M, 4M, 10M) are shown in Figure 1-3. Figure 2 As shown in the figure, analysis shows that with the increase of iron ion concentration, more FeCl3 solution is deposited and covered on the surface of MWCNT, the network structure becomes denser, and the ion transport becomes more convenient.

[0041] The output voltage changes of the single film, single film plus gel without connecting the gate and the final MWCNT thin film device (single film plus gel connected to the gate) during the preparation process of Example 1 are shown in Figure 2. Figure 3 As shown in (a), analysis shows that the Seebeck coefficient of the thin film device of Example 1 has not increased on the original basis, indicating that 0M iron ions and MWCNTs cannot act on the field effect transistor structure (relevant performance tests are all carried out at room temperature).

[0042] Similarly, the output voltage changes of the single film, single film plus gel without connecting the gate and the prepared Fe-MWCNT thin film device (single film plus gel connected to the gate) in the preparation process of Example 2 are as follows: Figure 3 As shown in (b), analysis shows that the Seebeck coefficient of the device of Example 2 is increased by 57.6% on the original basis (the relevant performance tests are all carried out at room temperature).

[0043] The output voltage changes of the single film, single film plus gel without connecting the gate and the prepared Fe-MWCNT thin film device (single film plus gel connected to the gate) during the preparation process of Example 3 are shown in Figure 2. Figure 3As shown in (c), analysis shows that the Seebeck coefficient of the device of Example 3 is increased by 43% on the original basis (the relevant performance tests are all carried out at room temperature).

[0044] The ionic thermoelectric Fe-MWCNT thin film device is used in a thermal energy conversion device to effectively improve the thermoelectric performance.

[0045] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing an ionic thermoelectric Fe-MWCNT thin film device, characterized in that: The following steps are involved: The MWCNT film was covered with FeCl3·6H2O solution, and the film was extracted to obtain a Fe-MWCNT film. Fe-PAM gel was placed in the middle of the Fe-MWCNT film to obtain an ionic thermoelectric Fe-MWCNT film device based on a field-effect tube structure. The Fe-PAM gel is prepared by soaking PAM gel in FeCl3·6H2O.

2. The method for preparing an ionic thermoelectric Fe-MWCNT thin film device according to claim 1, characterized in that: The MWCNT membrane is prepared by mixing carbon nanotubes and sodium dodecylbenzenesulfonate in deionized water, ultrasonically mixing the mixture, and then vacuum filtering the mixture.

3. The method for preparing an ionic thermoelectric Fe-MWCNT thin film device according to claim 2, characterized in that: After the vacuum filtration of the MWCNT membrane is completed, the FeCl3·6H2O solution is poured onto the MWCNT membrane, and the membrane is vacuumed again to obtain a Fe-MWCNT membrane, which is dried at room temperature and cut.

4. The method for preparing an ionic thermoelectric Fe-MWCNT thin film device according to claim 1, characterized in that: The PAM gel is prepared by mixing acrylamide, potassium persulfate and N,N-methylenebisacrylamide and then gelling them in a drying oven.

5. The method for preparing an ionic thermoelectric Fe-MWCNT thin film device according to claim 1, characterized in that: The following steps are involved: (1) Preparation of PAM gel: 4-6 g of acrylamide was placed in a beaker containing 15-25 mL of deionized water and stirred magnetically until completely dissolved. Then, 20-30 mg of potassium persulfate and 0.8-1.2 mg of N,N-methylenebisacrylamide were added and magnetic stirring was continued until completely dissolved to obtain a polyacrylamide solution. The polyacrylamide solution was transferred to a mold and dried in a drying oven at 55-65 °C for 25-35 min to obtain a PAM gel. (2) Preparation of Fe-PAM gel: Take 1.5-2.5 mL of 2.8-3.2 mol / L ferric chloride hexahydrate solution, and soak the PAM gel prepared in step (1) in the ferric chloride hexahydrate solution for 10-14 h to obtain Fe-PAM gel; (3) Preparation of Fe-MWCNT film: 15-18 mg of multi-walled carbon nanotubes and 150-170 mg of sodium dodecylbenzene sulfonate were added to 25-35 mL of deionized water, ultrasonically crushed for 25-35 min, vacuum filtered with a nylon membrane filter, and then washed with deionized water. Then, 8-12 mL of ferric chloride hexahydrate solution was added, and vacuum filtered again for 1.5-2.5 h. The Fe-MWCNT film was dried in a vacuum drying oven at 55-65 °C for 0.5-1.5 h. (4) The Fe-MWCNT film is used as the thermoelectric layer, and the Fe-PAM gel is placed in the middle of the Fe-MWCNT film to obtain an ionic thermoelectric Fe-MWCNT film device.

6. The method for preparing an ionic thermoelectric Fe-MWCNT thin film device according to claim 5, characterized in that: In step (1), after the polyacrylamide solution is transferred to the mold, the mold is covered with plastic wrap.

7. The method for preparing an ionic thermoelectric Fe-MWCNT thin film device according to claim 5, characterized in that: In the step (3), ultrasonic grinding is performed for 5 seconds every 10 seconds.

8. An ionic thermoelectric Fe-MWCNT thin film device prepared by the method according to any one of claims 1 to 7.

9. Use of the ionic thermoelectric Fe-MWCNT thin film device according to claim 8 in a thermal energy conversion device.

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