Reduction of interlayer friction between bilayer hexagonal boron nitride nanosheets induced by electron redistribution

The reduction of interfacial friction among hexagonal boron nitride nanosheets (h-BNNSs) is important for their application in nanoelectromechanical systems. In this work, a novel method via adjusting the electron redistribution to reduce the interlayer friction of the h-BNNS bilayers is proposed based on the theoretical calculation of the relationship between electron distribution state and corresponding friction performance. The theoretical calculation is performed based on density functional theory with a fluoride h-BNNS bilayer as a model. Calculations suggested that fluorine atoms can strongly bond to the h-BNNS and promote electron redistribution, inducing interesting surface behaviors of the h-BNNS bilayer. Fluorine doping can reduce the interlayer friction and even make the upper layer bend when the fluorine doping ratios increase further. This bending can promote the upper layer slide relative to the lower one, achieving superlubricity. The reduction is related to the electron transfer between layers and within layers, which is caused by the change in electrostatics and van der Waals interaction between the layers that resulted from the electron redistribution. This work opens up a new strategy to control the frictional properties of two-dimensional nanomaterials and provides a favorable proof for experimental analysis.