Superlubricity Enabled by Load‐Driven Redistribution of Electrons

• Published in: Advanced materials interfaces Vol. 9; no. 9
• Main Authors: Cheng, Ziwen, Sun, Junhui, Zhang, Bozhao, Lu, Zhibin, Ma, Fei, He, Qi‐Chang
• Format: Journal Article
• Language: English
• Published: Weinheim John Wiley & Sons, Inc 01.03.2022; Wiley
• Subjects: Charge density; Electrons; Energy dissipation; first‐principles; Graphene; Interlayers; load‐driven; Nanomaterials; nano‐friction; Physics; Potential energy; Quantitative analysis; redistribution of electrons; Sliding; superlubricity
• ISSN: 2196-7350; 2196-7350
• DOI: 10.1002/admi.202101589

By first‐principles calculations, it is shown that the friction at solid‐solid interfaces between 2D nanomaterials (TDNMs), such as h‐BN and graphene, can be reduced nearly to zero even if the normal load is smaller than 5 GPa. The quantitative analysis of interfacial charge density demonstrates a detailed process in which the pressure‐driven redistribution of electrons alters interlayer coupling of TDNMs and that reveals the electronic‐scale mechanism of pressure‐tunable lateral sliding at 2D commensurable interfaces. The shift of interlayer interaction results in sliding potential energy surface (PES) from a corrugated state to a flattened one and, eventually, to a counter‐corrugated one as the load increases. The flattened PES at new critical load implies the absence of any energy dissipation during interfacial sliding, i.e., the occurrence of superlubricity during interfacial sliding. These results also give rise to a quantitative model for the load‐dependent behavior of nano‐friction and promote the critical condition of the low‐pressure‐induced superlubricity to an experimentally feasible range. Using first‐principles calculations, the authors reveal the electron‐scale origin of nonlinear dependence of lateral friction on normal pressure and predict a novel and feasible critical condition of normal pressure to achieve superlubricity at solid–solid interfaces. Reveling the law and nature of nano‐friction is important for promoting and even guiding the experiment exploring of pressure‐induced superlubricity.