PNNL

Abstract

Interaction of water-vapor with metal surfaces plays a critical role in many chemical processes, yet the atomistic mechanisms beyond surface adsorption under realistic conditions remain mostly elusive. Here, using in-situ aberration-corrected environmental transmission electron microscopy in combination with theoretical calculation and simulations, we reveal, for the first time, a pressure-dependent surface activation of Cu through water dissociation and reaction at elevated temperature. Upon water vapor exposure, a transition from the flat surface to a corrugated reconstruction surface on (011) lattice plane is characteristically noticed. Increasing water vapor pressure leads to further evolution of the corrugated surface, featuring a “bilayer” structure on the (001) lattice plane, which essentially involves the formation of a stable “Cu-O-H” phase as a consequence of the synergy between O insertion and dragging of surface Cu atoms by the OH, as corroborated by DFT calculation and simulation. These results highlight the rich dynamics of the interaction of water vapor with transition metals and provide unprecedented insights into water-involved chemical processes.