MWCNT/PEDOT复合材料的微观结构和热电性能

李重阳; 宋小勇; 陈莉莉; 陶颖; 陈志权; 赵宾

doi:10.13801/j.cnki.fhclxb.20220307.002

MWCNT/PEDOT复合材料的微观结构和热电性能

doi: 10.13801/j.cnki.fhclxb.20220307.002

1.
华北水利水电大学　电力学院，郑州 450045
2.
郑州师范学院　物理与电子工程学院，郑州 450044
3.
武汉大学　物理科学与技术学院，武汉 430072
4.
中原工学院　理学院，郑州 450007

基金项目: 国家自然科学基金(11805295；11665017)National Natural Science Foundation of China (11805295; 11665017)

详细信息

通讯作者:
李重阳，博士，讲师，研究方向为正电子湮没谱学及多孔材料微观结构表征　E-mail: lichongyang@ncwu.edu.cn

中图分类号: O59；O631.2
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出版历程
- 收稿日期: 2022-01-20
- 修回日期: 2022-02-16
- 录用日期: 2022-02-26
- 网络出版日期: 2022-03-09
- 刊出日期: 2023-02-15

Microstructure and thermoelectric properties of MWCNT/PEDOT composites

1.
College of Electric Power, North China University of Water Resources and Electric Power, Zhengzhou 450045, China
2.
School of Physical and Electrical Engineering, Zhengzhou Normal University, Zhengzhou 450044, China
3.
Hubei Nuclear Solid Physics Key Laboratory, Department of Physics, Wuhan University, Wuhan 430072, China
4.
School of Science, Zhongyuan University of Technology, Zhengzhou 450007, China

摘要

摘要: 热电转换技术能将大量的废弃热能转换为电能以重新利用，是一种绿色能源转换技术，可以有效提高能源利用效率，缓解煤炭、石油等主要化石类能源过度开采、使用带来的能源危机及环境污染问题，因此受到科研工作者的广泛关注，是近年来的研究热点。基于此，本文以电子型导电高聚物中机能较优的聚(3, 4-乙烯二氧噻吩)(PEDOT)作为研究主体，通过化学原位氧化聚合将多壁碳纳米管(MWCNT)复合到载体中得到MWCNT/PEDOT复合材料。利用XRD、拉曼、TEM及正电子湮没寿命(PAL)等方法对MWCNT/PEDOT复合材料的形貌和微观结构进行了系统研究，研究表明：当MWCNT含量高于24.9wt%时，复合材料中出现MWCNT团聚现象，其分散性变差。同时，MWCNT/PEDOT复合材料的热电性能测试结果显示，未掺杂PEDOT的电导率仅为7.5 S·m⁻¹，而MWCNT含量为30.1wt%时，该复合材料的电导率高达566.59 S·m⁻¹，提高近76倍。同时，30.1wt%MWCNT/PEDOT的功率因子(814.3×10⁻⁴ μW·(m·K²)⁻¹)相对于未掺杂PEDOT(14.5×10⁻⁴ μW·(m·K²)⁻¹)提高约56倍，这主要是由于PEDOT分子链与MWCNT掺杂物间π-π相互作用及MWCNT的高导电性。随着MWCNT含量的增加，PAL测试结果中第一寿命成分τ₁(即正电子在材料中湮没的第一寿命成分)的下降证实了该复合材料中MWCNT与PEDOT间界面变小或者界面间相互作用减弱，导致其热导率相对于未掺杂PEDOT有一定的上升，但远远低于功率因子的升高。最终，该MWCNT/PEDOT复合材料的热电优值(即热电材料Z_T值)由0.015×10⁻⁴升至0.45×10⁻⁴，增加了约30倍。结果表明：掺杂的高电导率MWCNT能够极大地提高PEDOT类电子型导电聚合物的热电性能。
- 热电复合材料 /
- 多壁碳纳米管 /
- 聚(3, 4-乙烯二氧噻吩) /
- 热电优值 /
- 热电转换技术
Abstract: Thermoelectric conversion technology can convert a large amount of waste heat energy into electric energy for reuse. It is a green energy conversion technology, which can effectively improve energy utilization, and alleviate the energy crisis and environmental pollution caused by the over-exploitation and utilization of coal, oil and other major fossil energy. Therefore, it has been widely concerned by researchers and has become a research hotspot recently. Base on this, one of the more excellent electronic conductive polymers, poly(3, 4-ethylenedioxythiophene) (PEDOT), was used as the research subject, and multiwall carbon nanotubes (MWCNT)/PEDOT composites were synthesized by chemical in situ oxidation synthesis method. X-ray diffraction, raman spectroscopy, transmission electron microscope and positron annihilation lifetime spectroscopy were used to study the microstructure of the composites, the results of which indicate that when the MWCNT content is higher than 24.9wt%, the MWCNTs of MWCNT/PEDOT composites aggregate seriously and are badly dispersed. Thermal and electrical measurements of MWCNT/PEDOT composites show that their electrical conductivity increases sustainably with the MWCNT content increasing. For the pure PEDOT sample, the electrical conductivity is only 7.5 S·m⁻¹, and the electrical conductivity of MWCNT/PEDOT sample is up to 566.59 S·m⁻¹ at MWCNT content of 30.1wt%, the increase is nearly 76 times. Meanwhile, the power factor of the composites increases rapidly from 14.5×10⁻⁴ to 814.3×10⁻⁴ μW·(m·K²)⁻¹with the increase of 56, which is mainly due to the high conductivity of MWCNT and the π-π interaction between PEDOT molecular chain and MWCNT. With the increase of MWCNT content, the decrease of the first lifetime τ₁of positron annihilation in materials of PAL test confirms that the interface between MWCNT and PEDOT became smaller and the interfacial interaction between the MWCNT and PEDOT was weakened. As a result, the thermal conductivity of the composite exhibits a bit increase with the addition of MWCNT, but it was far lower than the increase of power factor. Eventually, the thermoelectric figure of merit (Z_T, an index or measure of the thermoelectric properties of a thermoelectric material) value of the MWCNT/PEDOT composites increases from 0.015×10⁻⁴ to 0.45×10⁻⁴, that's a nearly 30-fold increase. In summary, the doped MWCNT of higher conductivity can greatly enhance the thermoelectric properties of electronic conductive polymers of PEDOT.
- thermoelectric composites /
- multiwall carbon nanotubes /
- poly(3, 4-ethylenedioxythiophene) /
- figure of merit /
- thermoelectric conversion technology

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图 1 不同多壁碳纳米管(MWCNT)含量的MWCNT/聚(3, 4-乙烯二氧噻吩)(PEDOT)复合材料的XRD图谱

Figure 1. XRD patterns of different multiwall carbon nanotubes (MWCNT) contents of MWCNT/poly(3, 4-ethylenedioxythiophene) (PEDOT) composites

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图 2 不同MWCNT含量的MWCNT/PEDOT复合材料的拉曼光谱图(图2(b)为图2(a)的局部放大图)

Figure 2. Raman spectrogram of different MWCNT contents of MWCNT/PEDOT composites (Fig.2(b) is the local magnified view of Fig.2(a))

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图 3 不同MWCNT含量的MWCNT/PEDOT复合材料 ((a)~(e)) 及纯净MWCNT (f) 的高分辨TEM图像

((a)-(e)) MWCNT content is 0wt%, 11.4wt%, 19.7wt%, 24.9wt% and 30.1wt%, respectively

Figure 3. High resolution TEM images of different MWCNT contents of MWCNT/PEDOT composites ((a)-(e)) and pure MWCNT (f)

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图 4 不同MWCNT含量的MWCNT/PEDOT复合材料的正电子寿命$ {\tau }_{1} $和$ {\tau }_{2} $及对应强度I₁和I₂的变化曲线

Figure 4. Variation of positron lifetime $ {\tau }_{1} $, $ {\tau }_{2} $ and intensity I₁, I₂ measured for MWCNT/PEDOT as a function of MWCNT content

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图 5 不同MWCNT含量的MWCNT/PEDOT复合材料冷压后电导率 (a)、塞贝克系数 (b) 和功率因子 (c) 随测试温度的变化曲线

Figure 5. Variation of electrical conductivity (a), Seebeck coefficient (b) and power factor (c) for MWCNT/PEDOT composites with various MWCNT contents as a function of temperature

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图 6 室温下不同MWCNT含量的MWCNT/PEDOT复合材料的电导率 (a)、塞贝克系数 (b) 和功率因子 (c) 的变化曲线

Figure 6. Electrical conductivity (a), Seebeck coefficient (b) and power factor (c) for MWCNT/PEDOT composites with various MWCNT contents measured at room temperature

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图 7 (a) 30~111^oC间不同MWCNT含量的MWCNT/PEDOT复合材料的热扩散系数；室温下不同MWCNT含量的MWCNT/PEDOT复合材料的晶格热导率 (b)、热导率 (c) 和热电优值Z_T值 (d) 变化曲线

Figure 7. (a) Thermal diffusivity of the MWCNT/PEDOT composites with various MWCNT contents between 30-110^oC; Lattice thermal conductivity (b), thermal conductivity (c) and thermoelectric figure of merit Z_T value (d) for the MWCNT/PEDOT composites with various MWCNT contents at room temperature

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