ZnO纳米线基MWNTs/PVDF复合热电材料的制备及特性研究

Fabrication and properties of ZnO nanowire based MWNTs/PVDF composite thermoelectric materials

将不同比例的多壁碳管(MWNTs)与聚偏二氟乙烯(PVDF)聚合物混合后,喷涂于n型ZnO半导体纳米线阵列上,制备了一种新型ZnO纳米线基MWNTs/PVDF热电复合材料.与以往采用价格昂贵的p型与n型单壁碳纳米管(SWNTs)与聚合物混合制备的复合热电材料特性相比,这种新型热电复合材料在降低制造成本的同时,利用分散于聚合物中MWNTs的一维电子传输特性及形成的大量界面势垒,加上ZnO半导体纳米线具有的较高载流子密度与迁移率,提高了复合热电材料中电子的输运特性,增加了材料对声子的散射强度.测试发现,在一定的温度梯度下,随着MWNTs添加质量百分比的增加,热电材料的温差电动势和电导率也随之增加,但其Seebeck系数变化量不大.研究表明,这种热电材料有望替代采用p型与n型SWNTs构建的SWNTs/PVDF复合热电材料.研究结果对开发超轻、无毒、廉价、可应用于各种微纳电子领域的新型电源具有重要的参考价值.

In this article, multi-walled carbon nanotubes（MWNTs） and polyvinylidene fluoride（PVDF） were ultrasonic mixed with concentration of nanotubes ranging from 15 wt% to 75 wt%. The different MWNTs/PVDF mixtures were sprayed on the surface of n-type ZnO semiconductor nanowire arrays, and a new-type ZnO nanowire based MWNTs/PVDF polymeric thermoelectric composite materials were prepared. Compared with the previous carbon nanotube/polymer thermoelectric materials prepared using expensive p-type and n-type single-walled carbon nanotubes（SWNTs） and polymer hybrid, the prepared ZnO nanowire based MWNTs/PVDF samples presented excellent thermoelectric properties. The one dimensional conducting pathways and good electrical conductivity of the nanotubes, and the higher carrier density and mobility of ZnO semiconductor nanowires can effectively help enhance the electronic transport performance. Due to the introduction of a lot of phonon scattering points by mixing the dispersed MWNTs and ZnO nanowires into the polymer, the thermal conductivity of the thermoelectric composite materials can be dramatically decreased. Also, the preparation method for the composite thermoelectric materials is relatively simple and inexpensive. The experimental results found that the thermoelectric voltage and conductivity increased with the increasing of the weight concentration of MWNTs under a certain temperature gradient condition. And the amplitude of variation of Seebeck coefficient was not obvious in the whole range of tested temperature. The ZnO nanowire based MWNTs/PVDF composite thermoelectric materials are promising to replace previous SWNTs/polymer thermoelectric composites. This study suggests that the new-type thermoelectric composite materials are possible to provide the basis for further applications of lightweight, low-cost, and nontoxic thermoelectric polymer composites in the micro-nano electronic fields.