Exceptionally Strong Hydrogen Bonds Affect the Surface Energy of Colloidal Nanocrystals: Methylamine and Water Adsorption on PbS

Abstract

First-principles calculations for colloidal PbS nanocrystals reveal a sizable dependence of surface energy on the solution environment. In vacuum, the bare (100) surface is more stable than the bare (111) surface. Methylamine adsorption, however, preferentially lowers the energy of the unreconstructed (111), but the lowering is insufficient to reverse the energy order. Methylamine coadsorption with water can make the (111) surface most stable. The energy lowering is explained in terms of an exceptionally strong hydrogen bonding at the solution-solid interface.