阅读说明：本技术 一种二维过渡金属碳化物/碲化铋或其衍生物基热电复合材料及其制备 (Two-dimensional transition metal carbide/bismuth telluride or derivative thereof based thermoelectric composite material and preparation thereof ) 是由 范宇驰 陆晓芳 王连军 张琪昊 顾士甲 刘永平 江莞 于 2019-10-14 设计创作，主要内容包括：本发明涉及一种二维过渡金属碳化物/碲化铋或其衍生物基热电复合材料及其制备。该复合材料包括：硅烷偶联剂改性的碲化铋或其衍生物基热电材料和MXene。该制备方法包括：将碲化铋或其衍生物基热电材料用硅烷偶联剂改性,然后与MXene异相沉积,烧结。该复合材料具有较低的热导率和较高的电导率。该方法成本低、简单易行、适用范围广、易于工业化批量生产等特点。(The invention relates to a two-dimensional transition metal carbide/bismuth telluride or derivative thereof-based thermoelectric composite material and a preparation method thereof. The composite material comprises: silane coupling agent modified bismuth telluride or derivative thereof based thermoelectric material and MXene. The preparation method comprises the following steps: modifying the bismuth telluride or the derivative thereof based thermoelectric material with a silane coupling agent, then depositing with MXene out of phase, and sintering. The composite material has lower thermal conductivity and higher electrical conductivity. The method has the characteristics of low cost, simplicity, practicability, wide application range, easiness in industrial batch production and the like.)

1. A two-dimensional transition metal carbide/bismuth telluride or derivative thereof-based thermoelectric composite material is characterized by comprising the following components in a mass ratio of 1: 0.002-0.1 silane coupling agent modified bismuth telluride or its derivative based thermoelectric material and MXene.

2. The composite material of claim 1, wherein MXene is a transition metal carbide having a two-dimensional platelet structure and a composition represented by M_n+1X_nT_xWherein N is 1,2 or 3, M comprises one or more of transition metals Sc, Ti, Zr, Hf, V, Nb, Ta, Cr and Mo, X is C or N, and T is a functional group containing F or O.

3. The composite material of claim 1, wherein the bismuth telluride or derivative thereof-based thermoelectric material comprises: bi₂Te₃、Sb₂Te₃、Bi₂Se₃、Bi_xSb_2-xTe₃Or Bi₂Te_xSe_3-xWherein x is 0.2-0.8.

4. A preparation method of a thermoelectric composite material based on two-dimensional transition metal carbide/bismuth telluride or derivatives thereof comprises the following steps:

modifying the bismuth telluride or derivative thereof based thermoelectric material with a silane coupling agent, then depositing the modified bismuth telluride or derivative thereof with MXene in an out-phase manner, and sintering to obtain the two-dimensional transition metal carbide/bismuth telluride or derivative thereof based thermoelectric composite material, wherein the mass ratio of the bismuth telluride or derivative thereof based thermoelectric material to the silane coupling agent to the MXene is 1: 1: 0.002-0.1.

5. The method of claim 4, wherein the bismuth telluride or derivative thereof-based thermoelectric material is prepared by a wet chemical method, and the wet chemical method comprises a hydrothermal method, a solvothermal method or a sol-gel method.

6. The method according to claim 4, wherein the modification of the bismuth telluride or its derivative-based thermoelectric material with a silane coupling agent is carried out in toluene or an alcohol solution.

7. The method according to claim 4, wherein the modification temperature is 130-160 ℃ and the modification time is 6-8 h.

8. The method of claim 4, wherein the sintering process comprises spark plasma rapid sintering, hot press sintering, or hot isostatic pressing sintering.

9. Use of a composite material according to claim 1.

Technical Field

The invention belongs to the field of bismuth telluride based or bismuth telluride derivative composite thermoelectric materials and preparation thereof, and particularly relates to a two-dimensional transition metal carbide/bismuth telluride or bismuth telluride derivative based thermoelectric composite material and a preparation method thereof.

Background

Bismuth telluride-based and its derivatives have attracted much attention since the 50 s of the 20 th century and are considered as the basis of high performance thermoelectric materials in the low-to-intermediate temperature range. From Sb₂Te₃，Bi₂Te₃And Bi₂Se₃The excellent Thermoelectric (TE) properties of the representative bismuth telluride-based materials are mainly attributed to their high Power Factor (PF) and low thermal conductivity (κ) resulting from weak interlayer bonding by van der waals forces. Research shows that the thermoelectric property is optimized by isoelectronic external doping to prepare the obtained ternary compound (such as n-type Bi)₂Te_{3- x}Se_xAnd p-type Bi_2-xSb_xTe₃) The TE performance of the material is greatly improved, the maximum ZT is about 1, and the material is also the best commercial TE material at present and is mainly applied to refrigeration near room temperature. However, this lower conversion efficiency cannot be applied to waste heat recovery around room temperature. Therefore, it is particularly important to further improve ZT (or average ZT) of the bismuth telluride-based thermoelectric material in the entire temperature range.

To achieve higher TE performance, there are currently mainly strategies including extrinsic doping, intrinsic defect engineering, nanostructures and texturing. However, achieving an increase in overall ZT over a wide temperature range is very challenging because of the difficulty in tuning charge and phonon transport in combination. Although excessively high ZT values have been reported in some bismuth telluride-based thermoelectric compounds by these methods, few efficient thermoelectric devices have been reported, particularly for power generation. The operating efficiency of current commercial TE power generation modules is only about 4%, which is much lower than expected.

In contrast, the recombination of the nanoscale second phase can provide a rich heterogeneous interface andgrain boundaries can greatly improve charge and phonon transport behavior in the composite, thereby optimizing ZT over a wide temperature range. For example, in Bi₂Te₃The introduction of one-dimensional nanoparticles can lead to a sharp reduction in thermal conductivity while increasing the PF. On this basis, the compounding of two-dimensional (2D) nanomaterials such as graphene should exhibit quite significant effects due to their unique properties, such as high surface area and grain boundary-like morphology. However, the graphene composite bismuth telluride-based thermoelectric material has few examples of success in optimizing thermoelectric performance, because the graphene is obtained by reducing graphene oxide, the conductivity of the graphene composite bismuth telluride-based thermoelectric material is low, and the structure of the graphene composite bismuth telluride-based thermoelectric material is damaged to a certain extent, which is not enough to further improve the conductivity of the bismuth telluride-based thermoelectric material. In addition, due to the high surface area of the two-dimensional material, the uniform dispersion of the two-dimensional material in the matrix is difficult to achieve by the traditional composite method, such as zone melting in-situ composite or ball milling composite. [ Huaicao Tang, et al. NanoEnergy 49(2018) 267-273-][Raghavendra Nunna,et al.Energy Environ.Sci.,2017,10,1928-1935][Peng-an Zong,et al.Energy Environ.Sci.,2017,10,183-191]While severe agglomeration of the second phase cannot be prevented in the composite material, the introduced second phase inversely deteriorates TE properties and mechanical properties. MXene, also a two-dimensional material, has ultrahigh hydrophilicity and metal transmission performance, and the conductivity is very high up to 4600S/cm. However, no MXene thermoelectric composite material is found at present. The high-performance MXene/bismuth telluride-based thermoelectric composite material is hopefully prepared by reasonably designing MXene composite components and the preparation process of the composite material, and has important significance for development and application of the thermoelectric material.

Disclosure of Invention

The invention aims to solve the technical problem of providing a two-dimensional transition metal carbide/bismuth telluride or derivative thereof-based thermoelectric composite material and a preparation method thereof, so as to overcome the defects of nonuniform dispersion, low electrical conductivity, high thermal conductivity and the like of the bismuth telluride-based thermoelectric composite material in the prior art.

The invention provides a two-dimensional transition metal carbide/bismuth telluride or derivative thereof-based thermoelectric composite material, which comprises the following components in percentage by mass: 0.002-0.1 silane coupling agent modified bismuth telluride or its derivative based thermoelectric material and MXene.

The MXene is any one of two-dimensional layered inorganic materials composed of transition metal carbide with the thickness of several atomic layers. The composition may be represented as M_n+1X_nT_xWherein N is 1,2 or 3, M comprises one or more of transition metals Sc, Ti, Zr, Hf, V, Nb, Ta, Cr and Mo, X is C or N, and T is a functional group containing F or O.

The bismuth telluride or derivative thereof-based thermoelectric material includes: bi₂Te₃、Sb₂Te₃、Bi₂Se₃、Bi_xSb_2-xTe₃Or Bi₂Te_xSe_3-xWherein x is 0.2-0.8.

The invention also provides a preparation method of the two-dimensional transition metal carbide/bismuth telluride or derivative thereof based thermoelectric composite material, which comprises the following steps:

modifying the bismuth telluride or derivative thereof based thermoelectric material with a silane coupling agent, then depositing the modified bismuth telluride or derivative thereof with MXene in an out-phase manner, and sintering to obtain the two-dimensional transition metal carbide/bismuth telluride or derivative thereof based thermoelectric composite material, wherein the mass ratio of the bismuth telluride or derivative thereof based thermoelectric material to the silane coupling agent to the MXene is 1: 1: 0.002-0.1.

The bismuth telluride or derivative thereof based thermoelectric material is prepared by a wet chemical method, wherein the wet chemical method comprises a hydrothermal method, a solvothermal method or a sol-gel method.

The modification of the bismuth telluride or the derivative thereof based thermoelectric material by the silane coupling agent is carried out in toluene or alcohol solution.

The silane coupling agent includes APTS.

The modification temperature is 130-160 ℃, and the modification time is 6-8 h.

The sintering method comprises a discharge plasma rapid sintering method, a hot pressing sintering method or a hot isostatic pressing sintering method.

The invention also provides an application of the thermoelectric composite material based on the two-dimensional transition metal carbide/bismuth telluride or the derivative thereof.

The invention provides a method for preparing bismuth telluride or derivative-based nano powder by a wet chemical method, which comprises the steps of modifying the surface of the powder, preparing uniformly dispersed MXene/bismuth telluride-based thermoelectric powder by a heterogeneous deposition composite method with a two-dimensional material MXene, and sintering and forming to obtain the MXene/bismuth telluride-based thermoelectric material. The introduction of MXene not only increases a phonon scattering interface and reduces the thermal conductivity of the material, but also the high electrical conductivity of MXene provides more carriers for the composite material, adjusts the electrical property of the material and finally obtains the high-performance thermoelectric material.

Advantageous effects

The invention realizes the uniform composition of MXene and bismuth telluride based nano thermoelectric powder through heterogeneous deposition, and prepares the high-performance MXene/bismuth telluride based thermoelectric material through sintering. The thermoelectric composite material enhances phonon scattering due to the introduction of MXene, greatly reduces the thermal conductivity, provides more current carriers due to the high electrical conductivity of the MXene, realizes the comprehensive control of thermoelectricity, and obtains high thermoelectric performance. The invention also has the characteristics of low cost, simplicity, practicability, wide application range, easiness for industrial batch production and the like.

Drawings

FIG. 1 shows MXene/Bi prepared in example 6_0.4Sb_1.6Te₃The thermoelectric conversion efficiency of (1) is plotted against the change in temperature difference;

FIG. 2 shows MXene/Sb prepared in example 1₂Te₃Powder SEM appearance atlas;

FIG. 3 shows MXene/Bi prepared in example 2_0.5Sb_1.5Te₃XRD spectrum of the powder;

FIG. 4 shows MXene/Bi prepared in example 3₂Te₃The cross section SEM appearance of (1);

FIG. 5 shows MXene/Bi prepared in example 4_0.4Sb_1.6Te₃Graph of thermal conductivity versus temperature of;

FIG. 6 shows MXene/Bi prepared in example 5_0.4Sb_1.6Te₃Graph of ZT values versus temperature;

FIG. 7 shows Ti in an example of the present invention₃C₂T_xSEM topography of (a).

Detailed Description

The invention will be further illustrated with reference to the following specific examples. It should be understood that these examples are for illustrative purposes only and are not intended to limit the scope of the present invention. Further, it should be understood that various changes or modifications of the present invention may be made by those skilled in the art after reading the teaching of the present invention, and such equivalents may fall within the scope of the present invention as defined in the appended claims.

Examples of the invention Ti₃C₂T_xThe preparation method comprises the following steps: 1.6g LiF are dispersed in 20ml 9mol/L HCl solution, 0.8g Ti is slowly added₃AlC₂Stirred at 30 ℃ for 24 h. Centrifuging and washing the obtained product with water at a rotation speed of 3500r/min for three times, ultrasonically stripping at an ultrasonic power of 30% for 30min, centrifuging at the same rotation speed, and collecting supernatant to obtain thin Ti layer₃C₂T_xThe SEM image is shown in fig. 7, indicating that: ti prepared by the invention₃C₂T_xLight and thin and has no impurities on the surface.