Volcanic relationship between wettability of the interface and water migration rate in solar steam generation systems

Capturing solar energy as heat for water treatment has become a substantial approach to obtain freshwater. To obtain higher performance, the understanding of the mechanism of how water molecules interact with the interface is particularly fundamental, because the migration process of water molecules on the evaporation interface will directly affect the performance of the device. Herein we regulate the number of hydroxyl groups on the surface of reduced graphene oxide quantitatively, to study the effect of different wettability of interfaces on the performance of solar water generators. The water evaporation performance displays a volcanic shape as increasing wettability. Calculated by the computational chemistry method, deviation from proper wetting humidity is not conducive to the migration of water molecules from the surface. The double-edged sword effect of wettability on performances is clarified, and the surface energy density is the key to break through the limit by the finite element method.