Macro-superlubricity in sputtered MoS 2 -based films by decreasing edge pinning effect

To date, MoS 2 can only be achieved at microscale. Edge pinning effect caused by structure defects is the most obvious barrier to expand the size of structural superlubricity to macroscale. Herein, we plan to pin edge planes of MoS 2 with nanospheres, and then the incommensurate structure can be formed between adjacent rolling nanoparticles to reduce friction. The sputtered MoS 2 film was prepared by the physical vapor deposition (PVD) in advance. Then enough Cu 2 O nanospheres (∼40 nm) were generated in situ at the edge plane of MoS 2 layers by liquid phase synthesis. An incommensurate structure (mismatch angle ( θ ) = 8°) caused by MoS 2 layers was formed before friction. The friction coefficient of the films (5 N, 1,000 r/min) was ∼6.0×10 −3 at the most. During friction, MoS 2 layers pinned on numerous of Cu 2 O nanoparticles reduced its edge pinning effect and decreased friction. Moreover, much more incommensurate was formed, developing macro-superlubricity.