Nanoconfined polymer brushes for enhanced solar steam generation with antifouling and self-cleaning properties

Abstract

Interfacial solar steam generation is a promising technology for freshwater recovery from seawater and wastewater. However, surface salt crystallization and/or fouling on evaporators significantly reduce the long-term water evaporation efficiency. To address this issue, a new type of nanoconfined polymer brush (PB) with amide functional groups is designed and employed for improved antifouling properties and enhanced water evaporation. The PB utilizes graphene oxide nanosheets of atomic thickness as the substrate, with polymers growing on the nanosheets as bristles. The hydrophilic amide groups and nano-space confinement of PBs create layers with strong Donnan effect that trap five-fold more intermediate water (IW) than bulk water. Consequently, the high contents of IW act as an effective water evaporation source within the nanoconfined channels, preventing crystallization and enhancing water evaporation (2.25 kg m -2 h -1 ) with a light-to-heat conversion efficiency of about 86.9%. The evaporator based on PBs bring a new avenue for achieving a high solar steam generation efficiency with excellent salt self-cleaning capacity.