Insights into the mechanism of metal-polymer contact electrification for triboelectric nanogenerator via first-principles investigations
Insights into the mechanism of metal-polymer contact electrification for triboelectric nanogenerator via first-principles investigations
复制标题
通过第一性原理研究深入了解摩擦纳米发电机金属-聚合物接触起电机制
DOI：
10.1016/j.nanoen.2018.04.025
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发表时间：
2018-06-01
期刊：
影响因子：
17.6
通讯作者：
Hu, Yanqiang
中科院分区：
文献类型：
--
作者：
Wu, Jun;Wang, Xiaoli;Hu, Yanqiang
表面微纳米结构和材料改性是提高摩擦电纳米发电机输出性能的主要方法。然而，它们如何发挥作用的微观机制尚不清楚。本文以滕氏的典型材料对Al-PTFE为例，通过第一性原理研究金属-聚合物接触带电的机理，为触头的优化设计提供理论依据。我们论证了接触材料的界面势垒是与接触带电有关的更基本的参数，而不是被认为与电荷传输量成正比的有效功函数差。研究了电荷转移与界面距离的关系。我们证实，电荷转移受接触区域上的应力的影响很大，甚至可以在没有接触的情况下发生。在此基础上，提出了Teng表面微纳米结构的设计目标应是使接触区域处于适当的应力状态，而不是仅仅增加接触面积，并通过纳米结构提高接触带电有效范围内的比表面积，以自由产生额外的电荷转移。为了给研究较少的接触材料表面改性提供理论依据，对电荷转移的方向、驱动力和内在原因进行了研究。结果表明，电子受体是聚四氟乙烯表面的最低空分子轨道，电荷转移的驱动力是电子受体产生的静电引力。此外，还研究了界面化学键在聚四氟乙烯中的关键作用和内在机理。我们认为，对触头材料进行化学修饰的根本目的应该是降低电子受体材料表面的LUMO能级。
Surface micro/nano structures and materials modification are the major methods to enhance the output performance of triboelectric nanogenerator (TENG). However, the microcosmic mechanism on how they take effect has not been clear yet. Herein, the typical material pair Al-PTFE of TENG is taken as the example to study the mechanism of metal-polymer contact electrification via first-principles investigations and provide theoretical basis for the optimized design of TENG.We demonstrate that the interface barrier of the contact materials is the more fundamental parameter related to contact electrification, rather than the effective work function difference which has been thought to be proportional to the amount of charge transfer. The relationship between charge transfer and interface distance is also investigated. We confirm that charge transfer is significantly affected by the stress on the contact region, and it can even occur without contact. Based on the results, we propose that the surface micro/nano structures design on TENG should aim at making the contact regions in an appropriate stress state instead of only increasing the contact area, and improving the specific surface areas in the effective range of contact electrification via nanostructures for generating extra charge transfer freely.In order to provide theoretical basis for surface modification on contact materials which has been little studied, the direction, driving force and the intrinsic cause of charge transfer are investigated. It is demonstrated that the electrons acceptor is the LUMO (lowest unoccupied molecular orbital) on PTFE surface, and the driving force of charge transfer is the electrostatic attraction generated by the electrons acceptor. In addition, the key role and intrinsic mechanism of the interface chemical bond in PTFE is studied. We propose that the fundamental goal of chemical modification on contact materials should be to lower the LUMO energy level on the surface of electron acceptor materials.