Evolution of Water Structures on Stepped Platinum Surfaces

Abstract

Water/solid interfaces are relevant and have been studied extensively, however, with little understanding on stepped surfaces. We use a genetic algorithm method on top of density functional theory to determine water structures on Pt(221) and (553) surfaces. By including screened van der Waals (vdW) forces, we uncover a series of novel one- (1D) and two-dimensional (2D) water structures, which are essentially determined by the atomic geometry of Pt surfaces. We find that, with increasing water coverage, water–metal vdW interactions, water–metal electrostatic interactions, and water–water interactions in turn dictate the evolution of water structures. In particular, the step feature provides the templating effects for the formation of 1D water chains by modulating water–metal interactions, whereas the terrace is crucial to the formation of 2D water networks by altering H-bonds. These findings rationalize several key experimental observations and provide critical clues for understanding water/solid interfaces.