An ultra-low thermal conductivity single-walled carbon nanotube-based group ib noble metal p-type doped thin film, a preparation method and application thereof

Abstract

The application discloses a single-walled carbon nanotube-based group IB noble metal P-type doped film with ultra-low thermal conductivity and a preparation method and application thereof, and belongs to the technical field of energy conversion. The preparation method of the film comprises the following steps: S1, preparation of a single-walled carbon nanotube dispersion liquid; S2, preparation of a single-walled carbon nanotube film; S3, evaporation of a group IB noble metal; and S4, calcination of the film. The group IB noble metal is silver, copper or gold. The film with a thermal conductivity of less than or equal to 0.06 W / (m*K) is prepared by evaporation of the group IB noble metal on the single-walled carbon nanotube film and calcination, and the problem that wearable flexible heating materials are difficult to realize high-efficiency thermoelectric conversion at low voltage due to the excessively high intrinsic thermal conductivity of carbon nanotubes in the prior art is solved. The film has the potential to be applied to the preparation of flexible wearable thermoelectric materials.

Description

Technical Field

[0001] This invention relates to the field of energy conversion technology, specifically to a single-walled carbon nanotube-based IB group noble metal p-type doped thin film with ultra-low thermal conductivity, its preparation method, and its application. Background Technology

[0002] Single-walled carbon nanotubes (SWCNTs) possess excellent electrical conductivity and a lightweight texture, making them an ideal choice for flexible conductive and thermal materials. Their intrinsic carrier mobility is 5-10 times that of silicon, and their Young's modulus of 1 TPa makes them widely applicable in flexible wearable conductive materials. However, their ultra-high intrinsic thermal conductivity (>3000 W / (m·K)) results in low thermoelectric conversion efficiency. Doping modification can influence the thermal conductivity of SWCNTs by altering their microstructure and lattice. Therefore, selective P / N type doping of SWCNTs to improve thermoelectric conversion efficiency has become a major direction in carbon nanotube modification.

[0003] P-type and N-type doping of carbon nanotubes can effectively control their conductivity and carrier type, significantly improving the performance of devices such as thermoelectrics, solar cells, and transistors. This doping strategy provides a key pathway for developing flexible transparent conductive materials, low-power complementary circuits, and high-output thermoelectric generators, driving technological breakthroughs in flexible electronics and wearable devices.

[0004] Therefore, developing a carbon nanotube-based thermoelectric material with a simple preparation method and environmental friendliness has become an inevitable trend. Summary of the Invention

[0005] To address this issue, the present invention provides an ultra-low thermal conductivity single-walled carbon nanotube-based IB group noble metal p-type doped thin film, its preparation method, and its application, in order to solve the problem in the prior art that wearable flexible heating materials are difficult to achieve efficient thermoelectric conversion at low voltage due to the excessively high intrinsic thermal conductivity of carbon nanotubes.

[0006] To achieve the above objectives, the present invention provides the following technical solution: According to a first aspect of the present invention, a method for preparing a single-walled carbon nanotube-based group IB noble metal p-type doped thin film with ultra-low thermal conductivity is provided, specifically comprising the following steps: S1. Disperse sodium dodecylbenzenesulfonate and single-walled carbon nanotubes in deionized water to obtain a single-walled carbon nanotube dispersion. S2. Vacuum filter the single-walled carbon nanotubes at room temperature to obtain a single-walled carbon nanotube film. S3. Fix the single-walled carbon nanotube film onto a vacuum evaporation device and deposit Group IB noble metals. S4. The thin film coated with Group IB noble metals was calcined in a nitrogen atmosphere and then naturally cooled to room temperature to obtain a single-walled carbon nanotube-based Group IB noble metal P-type doped thin film with ultra-low thermal conductivity.

[0007] Further, the dispersion concentration of the single-walled carbon nanotubes in step S1 is 1-2 mg / mL, and the mass ratio of the single-walled carbon nanotubes to sodium dodecylbenzenesulfonate is 1:(5-20).

[0008] Furthermore, the vacuum degree of the vacuum filtration in step S2 is 0.085 MPa.

[0009] Furthermore, in step S3, the vacuum evaporation deposition has a deposition thickness of 1-10 nm, a deposition rate of 1 Å / s, and a vacuum degree of 10. -4 Pa.

[0010] Furthermore, the Group IB precious metal mentioned in step S3 is silver, copper, or gold.

[0011] Furthermore, the calcination temperature in step S4 is 750-900℃, the calcination time is 60-120 min, and the heating rate is 1-5℃ / min.

[0012] According to a second aspect of the present invention, an ultra-low thermal conductivity single-walled carbon nanotube-based group IB noble metal p-type doped thin film is provided, which is prepared by the above-described preparation method, and the thin film includes a substrate and a doped donor.

[0013] Furthermore, the substrate is a single-walled carbon nanotube film, and the doped donor is a group IB noble metal.

[0014] Furthermore, the thermal conductivity of the thin film is ≤0.06 W / (m·K).

[0015] According to a third aspect of the present invention, an application of a single-walled carbon nanotube-based group IB noble metal p-type doped thin film with ultra-low thermal conductivity is provided in the preparation of flexible wearable thermoelectric materials.

[0016] The present invention has the following advantages: This invention involves coating the surface of single-walled carbon nanotubes with Group IB metals via vacuum evaporation, followed by tube furnace calcination to allow bulk diffusion of the metal elements, resulting in sub-nanometer-scale doping. This method allows for effective control of the doping level by adjusting process parameters such as evaporation thickness, rate, calcination temperature, and time. The entire process requires no complex equipment, is simple to operate, and produces thin films with a thermal conductivity ≤0.06 W / (m·K), making it suitable for the field of flexible wearable thermoelectric materials. Attached Figure Description

[0017] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0018] The structures, proportions, sizes, etc. illustrated in this specification are only for the purpose of assisting those skilled in the art in understanding and reading the content disclosed herein, and are not intended to limit the conditions under which the present invention can be implemented. Therefore, they have no substantial technical significance. Any modifications to the structure, changes in the proportions, or adjustments to the size, without affecting the effects and objectives that the present invention can produce, should still fall within the scope of the technical content disclosed in the present invention.

[0019] Figure 1 A flowchart illustrating the preparation of an ultra-low thermal conductivity single-walled carbon nanotube-based IB group noble metal p-type doped thin film provided by this invention. Figure 2 The thermal diffusivity, thermal conductivity, and constant-pressure specific heat capacity of the thin films prepared in Examples 1, 4, and 7 of this invention and the thin films prepared without carbon nanotubes are shown in the diagram. Figure 3 Cold field scanning electron microscope (CSE) image and EDS image of a single-walled carbon nanotube-based group IB noble metal p-type doped thin film with ultra-low thermal conductivity provided in Examples 1-3 of this invention; Figure 4 Transmission electron microscope images of a single-walled carbon nanotube-based group IB noble metal p-type doped thin film with ultra-low thermal conductivity provided in Examples 1-3 of this invention at the 1 nm and 100 nm scales. Figure 5 The invention provides thermoelectric performance diagrams of single-walled carbon nanotubes with ultra-low thermal conductivity doped with different Group IB noble metals under different calcination temperatures and different vapor deposition thicknesses; wherein, Figure 5 (a) shows the thermoelectric properties of copper-doped single-walled carbon nanotube films calcined at different temperatures. Figure 5 (b) shows the thermoelectric properties of silver-doped single-walled carbon nanotube films calcined at different temperatures. Figure 5 (c) shows the thermoelectric properties of gold-doped single-walled carbon nanotube films calcined at different temperatures. Figure 5 (d) shows the thermoelectric properties of copper-doped single-walled carbon nanotube films at different deposition thicknesses. Figure 5 (e) shows the thermoelectric properties of silver-doped single-walled carbon nanotube films at different vapor deposition thicknesses. Figure 5 (f) shows the thermoelectric properties of gold-doped single-walled carbon nanotube films at different vapor deposition thicknesses. Detailed Implementation

[0020] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] According to a first aspect of the present invention, a method for preparing a single-walled carbon nanotube-based group IB noble metal p-type doped thin film with ultra-low thermal conductivity is provided, specifically comprising the following steps: S1. Disperse sodium dodecylbenzenesulfonate and single-walled carbon nanotubes in deionized water to obtain a single-walled carbon nanotube dispersion. S2. Vacuum filter the single-walled carbon nanotubes at room temperature to obtain a single-walled carbon nanotube film. S3. Fix the single-walled carbon nanotube film onto a vacuum evaporation device and deposit Group IB noble metals. S4. The thin film coated with Group IB noble metals was calcined in a nitrogen atmosphere and then naturally cooled to room temperature to obtain a single-walled carbon nanotube-based Group IB noble metal P-type doped thin film with ultra-low thermal conductivity.

[0022] In step S1, the dispersion concentration of single-walled carbon nanotubes is 1-2 mg / mL, and the mass ratio of single-walled carbon nanotubes to sodium dodecylbenzenesulfonate is 1:(5-20).

[0023] In step S2, the vacuum degree of vacuum filtration is 0.085 MPa.

[0024] In step S3, the vacuum evaporation deposition has a deposition thickness of 1-10 nm, a deposition rate of 1 Å / s, and a vacuum degree of 10. - 4 Pa.

[0025] In step S3, the Group IB precious metal is silver, copper, or gold.

[0026] In step S4, the calcination temperature is 750-900℃, the calcination time is 60-120min, and the heating rate is 1-5℃ / min.

[0027] According to a second aspect of the present invention, an ultra-low thermal conductivity single-walled carbon nanotube-based group IB noble metal p-type doped thin film is provided, which is prepared by the above-described preparation method, and the thin film includes a substrate and a doped donor.

[0028] The substrate is a single-walled carbon nanotube film, and the doped donors are group IB noble metals.

[0029] The thermal conductivity of the thin film is ≤0.06W / (m·K).

[0030] The technical route for preparing ultra-low thermal conductivity single-walled carbon nanotube-based group IB noble metal p-type doped thin films is as follows: Figure 1 As shown. Specifically, the prepared single-walled carbon nanotube dispersion is filtered through a vacuum filtration system to obtain a carbon nanotube-based thin film. After doping with group IB noble metals (silver, copper, gold), a group IB noble metal / single-walled carbon nanotube thin film is obtained. After calcination in a tube atmosphere resistance furnace under nitrogen atmosphere, a single-walled carbon nanotube-based group IB noble metal P-type doped thin film with ultra-low thermal conductivity is obtained.

[0031] To better illustrate the technical path of the present invention, the following embodiments and comparative examples are provided.

[0032] Example 1 S1. Disperse 1g of sodium dodecylbenzenesulfonate and 100mg of single-walled carbon nanotubes in 100mL of deionized water to obtain a single-walled carbon nanotube dispersion; wherein the purity of the single-walled carbon nanotubes is >95wt%. S2. Vacuum filter the single-walled carbon nanotubes at room temperature, setting the vacuum degree to 0.085 MPa, to obtain a single-walled carbon nanotube film with a size of 2 cm × 2 cm. S3. Fix the single-walled carbon nanotube film onto a vacuum evaporation apparatus and deposit silver; the evaporation rate is 1 Å / s, the evaporation thickness is 1 nm, and the vacuum degree is 10. -4 Pa, silver purity > 99.99%; S4. Place the thin film coated with Group IB noble metal into a tube furnace, heat it to 750℃ for calcination at a heating rate of 5℃ / min under a nitrogen atmosphere, and then cool it naturally to room temperature to obtain a single-walled carbon nanotube-based Group IB noble metal P-type doped thin film with ultra-low thermal conductivity.

[0033] Example 2 This embodiment is based on Embodiment 1, except that the metal vapor-deposited is copper, while the other specific parameters are the same as in Embodiment 1.

[0034] Example 3 This embodiment is based on Embodiment 1, except that the metal vapor-deposited is gold, while the other specific parameters are the same as in Embodiment 1.

[0035] Example 4 S1. Disperse 2g of sodium dodecylbenzenesulfonate and 100mg of single-walled carbon nanotubes in 100mL of deionized water to obtain a single-walled carbon nanotube dispersion; wherein the purity of the single-walled carbon nanotubes is >95wt%. S2. Vacuum filter the single-walled carbon nanotubes at room temperature, setting the vacuum degree to 0.085 MPa, to obtain a single-walled carbon nanotube film with a size of 2 cm × 2 cm. S3. Fix the single-walled carbon nanotube film onto a vacuum evaporation apparatus and deposit silver; the evaporation rate is 1 Å / s, the evaporation thickness is 10 nm, and the vacuum degree is 10. -4 Pa, silver purity > 99.99%; S4. Place the thin film coated with Group IB noble metal into a tube furnace, heat it to 900℃ for 120 min at a heating rate of 5℃ / min under a nitrogen atmosphere, and then cool it naturally to room temperature to obtain a single-walled carbon nanotube-based Group IB noble metal P-type doped thin film with ultra-low thermal conductivity.

[0036] Example 5 This embodiment is based on embodiment 4, except that the metal vapor-deposited is copper, while the other specific parameters are the same as in embodiment 4.

[0037] Example 6 This embodiment is based on embodiment 4, except that the metal vapor-deposited is gold, while the other specific parameters are the same as in embodiment 4.

[0038] Example 7 S1. Disperse 0.5g sodium dodecylbenzenesulfonate and 100mg single-walled carbon nanotubes in 50mL of deionized water to obtain a single-walled carbon nanotube dispersion; wherein the purity of the single-walled carbon nanotubes is >95wt%. S2. Vacuum filter the single-walled carbon nanotubes at room temperature, setting the vacuum degree to 0.085 MPa, to obtain a single-walled carbon nanotube film with a size of 2 cm × 2 cm. S3. Fix the single-walled carbon nanotube film onto a vacuum evaporation apparatus and deposit silver; the evaporation rate is 1 Å / s, the evaporation thickness is 5 nm, and the vacuum degree is 10. -4 Pa, gold purity > 99.99%; S4. Place the thin film coated with Group IB noble metal into a tube furnace, heat it to 800℃ for 60 min at a heating rate of 1℃ / min under a nitrogen atmosphere, and then cool it naturally to room temperature to obtain a single-walled carbon nanotube-based Group IB noble metal P-type doped thin film with ultra-low thermal conductivity.

[0039] Example 8 This embodiment is based on embodiment 7, except that the metal vapor-deposited is copper, while the other specific parameters are the same as in embodiment 7.

[0040] Example 9 This embodiment is based on embodiment 7, except that the metal vapor-deposited is gold, while the other specific parameters are the same as in embodiment 7.

[0041] Test Example 1 To verify the thermal conductivity of the thin film, this invention determined the thermal diffusion coefficient and thermal conductivity (κ) using the transient planar heat source method, and its isobaric specific heat capacity (Cp) using differential scanning calorimetry. The results were recorded in [the relevant documentation]. Figure 2 The present invention also prepared undoped metal single-walled carbon nanotube films as a control group. The film preparation method was the same as in Example 1, but without metal evaporation.

[0042] Depend on Figure 2 It can be seen that the thermal diffusivity, thermal conductivity, and isobaric specific heat capacity of the single-walled carbon nanotube-based IB group noble metal p-type doped thin films prepared by this invention are significantly lower than those of pure single-walled carbon nanotubes; the thermal conductivity of the IB-single-walled carbon nanotube thin films is significantly reduced, ranging from 0.032 to 0.045 W / (m·K), and the thermal diffusivity is extremely low at 0.107 mm. 2 / s (copper doped), 0.066mm 2 / s (silver doped) and 0.086mm 2 The / s (gold doping) indicates that the IB-single-walled carbon nanotube film effectively suppresses internal thermal diffusion. This property maintains a stable temperature gradient by minimizing rapid heat transfer to the cold side, thus preserving the driving force required for efficient thermoelectric energy conversion. Metal-doped films exhibit relatively low specific heat capacities, ranging from only 0.299 to 0.432 J / g / K, indicating that a considerable amount of thermal energy is required to raise the temperature per unit mass of the film by 1 °C. This leads to suppression of transient thermal response under fluctuating heat input. Therefore, when integrated into thermoelectric devices, the low Cp of the IB-single-walled carbon nanotube film helps improve the temporal stability of power output. Among the three doped films, copper-doped films exhibit the lowest thermal conductivity and isobaric specific heat capacity, but the highest thermal diffusivity among the three types; silver-doped films exhibit the lowest thermal diffusivity, with thermal conductivity close to that of copper-doped films and isobaric specific heat capacity close to that of gold-doped films; while gold-doped films exhibit the highest thermal conductivity and isobaric specific heat capacity. This is because the differences in atomic radius, electronegativity, and interaction with carbon among different metals lead to different scattering mechanisms for electron transport. Copper atoms introduce strong lattice distortion, effectively reducing thermal conductivity, but their small atomic mass results in a low specific heat capacity. Gold atoms, on the other hand, have a larger mass and therefore exhibit a higher specific heat capacity. Furthermore, their weaker interaction with the carbon lattice leads to higher thermal conductivity. The results demonstrate that the thermoelectric properties of the single-walled carbon nanotube-based Group IB noble metal p-type doped thin film prepared in this invention can be controlled by adjusting the doping with different Group IB noble metals.

[0043] Test Example 2 The surface microstructure of the films prepared in Examples 1-3 was characterized by cold field scanning electron microscopy and transmission electron microscopy.

[0044] Figure 3 These are cold field scanning electron microscope (CSE) images and EDS spectra of a single-walled carbon nanotube-based group IB noble metal p-type doped thin film with ultra-low thermal conductivity provided in Examples 1-3 of this invention. Figure 3 It can be seen that the thickness of the deposited layer was precisely controlled after vacuum evaporation, enabling a 1 nm thick Group IB metal layer to stably adhere to the surface of the single-walled carbon nanotube film. After annealing, the network structure of the single-walled carbon nanotubes became denser, and the originally aggregated carbon nanotubes exhibited a root-like morphology. During this process, the defect density of the carbon nanotube film decreased, thereby promoting the formation of a more compact structure. Simultaneously, energy dispersive spectroscopy analysis showed a complete coverage distribution of Group IB elements on the single-walled carbon nanotube film.

[0045] Depend on Figure 4 The transmission electron microscope images show that after doping with Group IB metals, the inter-tube spacing of carbon nanotubes decreased from 0.438 nm in the undoped state to 0.382 nm (copper doping), 0.382 nm (silver doping), and 0.378 nm (gold doping), respectively. This indicates that the defect density of the carbon nanotube film decreased after doping, thereby promoting the formation of a more compact structure.

[0046] Test Example 3 This invention uses a thermoelectric performance tester to detect the Seebeck coefficient and conductivity of the thin films prepared in Examples 1-9, and calculates the power factor. To better verify the effects of calcination temperature and deposition thickness on the thermoelectric properties of the thin films, this invention also prepared thin films with a calcination temperature of 800℃ and deposition thicknesses of 150 Å and 200 Å as controls, based on each example. The results are recorded in [document name missing]. Figure 5 The results show that the thermoelectric properties of the thin films exhibit significant temperature and thickness dependence, and that the Seebeck coefficient and conductivity exhibit a typical trade-off relationship typical of thermoelectric materials. Each metal modification system has an optimal temperature range and optimal deposition thickness, and can achieve the highest power factor under matched process conditions. Among the three noble metals, copper-doped carbon nanotube films have a superior power factor and better thermoelectric power generation potential.

[0047] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A method for preparing a single-walled carbon nanotube-based group IB noble metal p-type doped thin film with ultra-low thermal conductivity, characterized in that, Specifically, the following steps are included: S1. Disperse sodium dodecylbenzenesulfonate and single-walled carbon nanotubes in deionized water to obtain a single-walled carbon nanotube dispersion. S2. Vacuum filter the single-walled carbon nanotubes at room temperature to obtain a single-walled carbon nanotube film. S3. Fix the single-walled carbon nanotube film onto a vacuum evaporation device and deposit Group IB noble metals. S4. The thin film coated with Group IB noble metals was calcined in a nitrogen atmosphere and then naturally cooled to room temperature to obtain a single-walled carbon nanotube-based Group IB noble metal P-type doped thin film with ultra-low thermal conductivity.

2. The preparation method according to claim 1, characterized in that, The dispersion concentration of the single-walled carbon nanotubes in step S1 is 1-2 mg / mL, and the mass ratio of the single-walled carbon nanotubes to sodium dodecylbenzenesulfonate is 1:(5-20).

3. The preparation method according to claim 1, characterized in that, The vacuum degree of the vacuum filtration in step S2 is 0.085 MPa.

4. The preparation method according to claim 1, characterized in that, The vacuum evaporation in step S3 has a deposition thickness of 1-10 nm, a deposition rate of 1 Å / s, and a vacuum degree of 10. -4 Pa.

5. The preparation method according to claim 1, characterized in that, The Group IB precious metal mentioned in step S3 is silver, copper, or gold.

6. The preparation method according to claim 1, characterized in that, The calcination temperature in step S4 is 750-900℃, the calcination time is 60-120min, and the heating rate is 1-5℃ / min.

7. A single-walled carbon nanotube-based group IB noble metal p-type doped thin film with ultra-low thermal conductivity, prepared by the preparation method according to any one of claims 1-6, characterized in that, The thin film includes a substrate and a doped donor.

8. The thin film as claimed in claim 7, characterized in that, The substrate is a single-walled carbon nanotube film, and the doped donor is a Group IB noble metal.

9. The thin film as claimed in claim 7, characterized in that, The thermal conductivity of the thin film is ≤0.06W / (m·K).

10. The application of a single-walled carbon nanotube-based group IB noble metal p-type doped thin film with ultra-low thermal conductivity in the preparation of flexible wearable thermoelectric materials, characterized in that, The thin film is obtained by the preparation method according to any one of claims 1-6.

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