Roughening of hcp metal surfaces induced by nitrogenadsorption

Abstract

Using DFT calculations and thermodynamic considerations, the structure of Ru, Os, and Re hcp(111) surfaces has been studied in the presence of a N₂ atmosphere. We find that N adsorption causes two-sided ridges consisting of hcp{132} faces to form on the initially planar hcp(111) surface. The rough hcp(132) surface has a high density of low-coordinated atoms and is expected to show a high bond-breaking activity. Since the roughening of hcp(111) is also favorable at elevated temperatures and pressures, it might be capable to change the activity of the hcp-catalysts.