| MWCNT/PEDOT复合材料的微观结构和热电性能 |
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| 引用本文： | 李重阳,宋小勇,陈莉莉,陶颖,陈志权,赵宾.MWCNT/PEDOT复合材料的微观结构和热电性能[J].复合材料学报,2023,40(2):860-871. |
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| 作者姓名： | 李重阳 宋小勇 陈莉莉 陶颖 陈志权 赵宾 |
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| 作者单位： | 1.华北水利水电大学 电力学院，郑州 450045 |
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| 基金项目： | 国家自然科学基金(11805295；11665017)National Natural Science Foundation of China (11805295; 11665017) |
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| 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ZT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。
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| 关 键 词： | 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 |
| 收稿时间： | 2022-01-20 |
Microstructure and thermoelectric properties of MWCNT/PEDOT composites |
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| Affiliation: | 1.College of Electric Power, North China University of Water Resources and Electric Power, Zhengzhou 450045, China2.School of Physical and Electrical Engineering, Zhengzhou Normal University, Zhengzhou 450044, China3.Hubei Nuclear Solid Physics Key Laboratory, Department of Physics, Wuhan University, Wuhan 430072, China4.School of Science, Zhongyuan University of Technology, Zhengzhou 450007, China |
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| 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)?1 with 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 τ1 of 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 (ZT, 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. |
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