  We study the role of electronegativity in sliding friction for five different
two dimensional (2D) monolayer systems using density functional theory (DFT)
with van der Waals (vdW) corrections. We show that the friction between the
commensurate 2D layered systems depends strongly on the electronegativity
difference of the involved atoms. All the 2D layered structures exhibit almost
the same magnitude of friction force when sliding along the nonpolar path,
independent of the material and the surface structures. In contrast, for
sliding friction along the polar path, the friction force obeys a universal
linear scaling law as a function of the electronegativity difference of its
constituent atoms. Further analyses demonstrate that atomic dipoles in the 2D
monolayers induced by the electronegativity difference enhance the corrugation
of charge distribution and increase the sliding barrier accordingly. Our
studies reveal that electronegativity plays an important role in friction of
low dimensional systems, and will provide a strategy for designing nanoscale
devices further.
