UNAM-National Nanotechnology Research Center, Bilkent University, 06800, Ankara, Turkey.
Chemistry Department, Bilkent University, 06800, Ankara, Turkey.
Sci Rep. 2018 Feb 6;8(1):2472. doi: 10.1038/s41598-018-20413-1.
Contact electrification (CE)-charging of surfaces that are contacted and separated, is a common phenomenon, however it is not completely understood yet. Recent studies using surface imaging techniques and chemical analysis revealed a 'spatial' bipolar distribution of charges at the nano dimension, which made a paradigm shift in the field. However, such analyses can only provide information about the charges that remained on the surface after the separation, providing limited information about the actual course of the CE event. Tapping common polymers and metal surfaces to each other and detecting the electrical potential produced on these surfaces 'in-situ' in individual events of contact and separation, we show that, charges are generated and transferred between the surfaces in both events; the measured potential is bipolar in contact and unipolar in separation. We show, the 'contact-charges' on the surfaces are indeed the net charges that results after the separation process, and a large contribution to tribocharge harvesting comes, in fact, from the electrostatic induction resulting from the generated CE charges. Our results refine the mechanism of CE providing information for rethinking the conventional ranking of materials' charging abilities, charge harvesting, and charge prevention.
接触带电（CE）-接触和分离表面的充电，是一种常见现象，但尚未完全理解。最近使用表面成像技术和化学分析的研究揭示了纳米尺度上电荷的“空间”双极性分布，这在该领域引发了范式转变。然而，这种分析只能提供有关分离后仍留在表面上的电荷的信息，提供有关 CE 事件实际过程的有限信息。通过相互敲击常见的聚合物和金属表面，并在接触和分离的各个事件中“原位”检测这些表面上产生的电势能，我们表明，在两个事件中，电荷在表面之间产生和转移；接触时测量的电势是双极性的，分离时是单极性的。我们表明，表面上的“接触电荷”实际上是分离过程后产生的净电荷，摩擦电荷收集的一个很大贡献实际上来自于由产生的 CE 电荷引起的静电感应。我们的结果改进了 CE 的机制，为重新思考材料充电能力、电荷收集和电荷防止的传统排序提供了信息。
