Water adsorption on hydrogen-passivated silicon nanowires from density functional theory with dispersion correction

Abstract

Density functional theory with semiempirical dispersion correction has been applied to investigate water monomer adsorption onto the surface of hydrogen-passivated silicon nanowires (h-SiNWs) of different shapes and growth orientations. We find that water adsorption is in the weak physisorption limit, leading to a hydrophobic surface. The adsorption site and orientation are determined by electrostatic interactions involving both the surface and interior atoms of the h-SiNWs and are not affected qualitatively by including the dispersion correction. The barrier for water diffusing on the surface of h-SiNWs depends sensitively on the nanowire facet and growth orientation. The barrier for water rotation is small, which may facilitate water cluster formation on the h-SiNWs.