Gas-Solid van der Waals Interaction Driving the Dynamic Evolution of Surface Nanostructures

Weak intermolecular forces are ubiquitous in chemistry, materials science, and biology, yet their direct role in gas-solid interfacial phenomena has remained elusive. Here, we show that under millibar-range H₂O vapor at room temperature, monolayer Au nanoislands on Au(111) undergo pronounced restructuring within seconds through particle migration, coalescence, and Ostwald ripening. The driving force of these rapid dynamics is identified as van der Waals interaction between H₂O molecules and surface Au atoms via dipole-dipole attraction. This effect is reinforced by the formation of transient H₂O-adsorbed Au adatom complexes, which lower the energy barrier for atomic detachment and migration. Our findings provide direct atomic-level evidence that weak physical interactions alone can reshape metal nanostructures, offering a new route to engineer the surface architectures under mild conditions.