Interaction energies, structure, and dynamics at functionalized graphitic structure-liquid phase interfaces in an aqueous calcium sulfate solution by molecular dynamics simulation

摘要

Molecular dynamics simulations were performed to study the effect of surface functional-ization 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 (-COCr, 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 Ca~(2+) and SO_4~(2-) ions.