Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemicals Physics, Chinese Academy of Sciences, Lanzhou 730000, China.
Phys Chem Chem Phys. 2019 Nov 28;21(44):24565-24571. doi: 10.1039/c9cp04825a. Epub 2019 Oct 30.
Atomic-scale friction theory, and even superlubricity, is inseparable from charge redistribution, but lacks a bridge to establish the potential link between them. Here, we first report a quantized charge density fluctuation surface (CDFS) by assembling silicene/graphene and germanene/graphene heterostructures and their corresponding homogeneous bilayers for DFT calculations. By observing the PES morphology, we see that it exhibits a decrease in friction by more than two orders of magnitude. A crucial physical quantity controlling the friction was found to be the charge density fluctuation during the friction process via analyzing the CDFSs. Such CDFS holds a universal applicability in van der Waals materials, and is recommended to explore the friction cooperating with PES. This will be a new idea for exploring whether friction is related to electrical properties by defining the conversion factor K for a wide series of interactions, including metallic, covalent, and van der Waals bonding. In particular, the same conversion factor K exists for van der Waals bonding, and a mutual identification between the CDFS and PES can be achieved.
原子尺度摩擦理论，甚至超滑，都离不开电荷再分配，但缺乏建立它们之间潜在联系的桥梁。在这里，我们首次通过组装硅烯/石墨烯和锗烯/石墨烯异质结构及其相应的同质双层结构进行 DFT 计算，报告了一个量化的电荷密度涨落表面（CDFS）。通过观察 PES 形态，我们发现它在摩擦过程中表现出超过两个数量级的摩擦力降低。通过分析 CDFS，我们发现一个关键的物理量控制着摩擦，即在摩擦过程中电荷密度的涨落。这种 CDFS 在范德华材料中具有普遍适用性，并建议与 PES 一起探索摩擦。这将是一个通过定义一系列相互作用（包括金属、共价和范德华键合）的转换因子 K，来探索摩擦是否与电性质有关的新想法。特别是，对于范德华键合，存在相同的转换因子 K，可以实现 CDFS 和 PES 之间的相互识别。
