Deciphering the Nanoscale Frictional Properties of Two-Dimensional SnSe and SnSe${}_2$ with Lateral Force Microscopy

In this study, we employed lateral force microscopy, a specialized technique within atomic force microscopy, to explore the nanoscale frictional properties of 2D SnSe and SnSe${}_2$ layers, and we compared these findings with graphene, a commonly used solid lubricant. Our results revealed that SnSe and SnSe2 layers exhibited superior lubricative performance compared to graphene with similar thickness, with SnSe${}_2$ demonstrating friction levels up to three times lower. This lower friction observed in SnSe${}_2$, as compared to SnSe, was further substantiated by extensive Density Functional Theory (DFT) calculations, confirming the intrinsic material properties contributing to their enhanced lubricative behavior.