CARBON 2010, 48, 1210-1223

Sanchez, F; Zhang, L

Molecular dynamics simulations were performed to study the effect of surface functionalization of graphitic structures on the molecular-scale energetic, structure, and dynamics of water and ions at graphite surface-liquid phase interfaces. Three types of carbon surface structures were investigated: a pristine graphite plane and two graphite planes functionalized with hydroxyl (- OH) and carboxylate (-COO-, deprotonated carboxyl) groups. A divalent salt, calcium sulfate, was combined with water to simulate an electrolyte liquid phase. Results highlighted the ordering of H2O molecules that occurs near graphite surfaces and revealed a subtle effect on the position of the H2O layers associated with ions and functional group type. Surface functionalization of the graphitic structures affected the H-bond network and the orientation of near surface H2O molecules, decreased the ion hydration, and significantly restrained the mobility of near surface H2O molecules and bulk Ca2+ and SO42- ions. © 2009 Elsevier Ltd. All rights reserved.