Wang Shichao, Wu Jiatao, Yang Fan, Xin Hong, Wang Lei, Gao Chunmei
College of Chemistry and Environmental Engineering, Shenzhen University, Shenzhen 518060, China.
Shenzhen Key Laboratory of Polymer Science and Technology, College of Materials Science and Engineering, Shenzhen University, Shenzhen 518060, China.
ACS Appl Mater Interfaces. 2021 Jun 9;13(22):26482-26489. doi: 10.1021/acsami.1c04786. Epub 2021 May 25.
It is crucial for thermoelectric (TE) devices to obtain both p-type and n-type materials and control charge carrier density. However, n-type thermoelectric materials are quite deficient and have lower thermoelectric properties. We report one oxygen-rich polymer named polyethylene glycol (PEG) for converting p-type single-walled carbon nanotubes (SWCNTs) to air-stable n-type thermoelectric materials. When pristine SWCNTs were doped with 2 mg·mL PEG in an ethanol solution, the optimal Seebeck coefficient of PEG/SWCNT composites reached -50.8 μV·K. The result of ultraviolet photoelectron spectroscopy demonstrated that the lone pair of oxygen atoms in the PEG chain has electron transferability to SWCNTs. According to the hard and soft acid and base theory, sodium hydroxide (NaOH) was further introduced to improve air stability and thermoelectric performance of doped SWCNTs. As a result, PEG/NaOH/SWCNT composites achieved the highest power factor of 173.8 μW·m·K at 300 K. Meanwhile, their final changes in electrical conductivity and the Seebeck coefficient are less than 8% in the investigation of air stability over two months. Inspired by this finding, we fabricated the TE generator composed of the pristine p-type SWCNTs and n-type PEG/NaOH/SWCNT composites. The maximum output power of this robust TE device reached 5.3 μW at a temperature gradient of 76 K, which is superior to many reported TE devices. Moreover, the experimental procedure is attractive as a sustainable process for materials preparation. Our study has indicated that the oxygen-rich polymer-functionalized SWCNTs have huge potential for developing air-stable n-type carbon-based thermoelectric materials.
对于热电（TE）器件而言，获得p型和n型材料并控制电荷载流子密度至关重要。然而，n型热电材料相当匮乏且热电性能较低。我们报道了一种名为聚乙二醇（PEG）的富氧聚合物，用于将p型单壁碳纳米管（SWCNT）转变为空气稳定的n型热电材料。当在乙醇溶液中用2 mg·mL的PEG掺杂原始SWCNT时，PEG/SWCNT复合材料的最佳塞贝克系数达到-50.8 μV·K。紫外光电子能谱结果表明，PEG链中的孤对氧原子具有向SWCNT转移电子的能力。根据软硬酸碱理论，进一步引入氢氧化钠（NaOH）以提高掺杂SWCNT的空气稳定性和热电性能。结果，PEG/NaOH/SWCNT复合材料在300 K时实现了173.8 μW·m·K的最高功率因数。同时，在两个月的空气稳定性研究中，它们的电导率和塞贝克系数的最终变化小于8%。受这一发现的启发，我们制造了由原始p型SWCNT和n型PEG/NaOH/SWCNT复合材料组成的TE发电机。在76 K的温度梯度下，这种坚固的TE器件的最大输出功率达到5.3 μW，优于许多已报道的TE器件。此外，该实验过程作为一种可持续的材料制备工艺很有吸引力。我们的研究表明，富氧聚合物功能化的SWCNT在开发空气稳定的n型碳基热电材料方面具有巨大潜力。
