Mechanically robust composite hydrogels for high performance solar driven interface evaporation

Three dimensional composite hydrogels have been good candidates for solar driven interfacial evaporation, and it has remained a great challenge to develop high performance hydrogel evaporators with excellent mechanical properties, high evaporation efficiency and rate, and outstanding durability. Here, we prepare a polyvinyl alcohol (PVA)/acidified carbon nanotubes (ACNTs) composite hydrogel for solar-powered desalination. ACNTs are uniformly dispersed in the hydrogel and forms hydrogel bonding with PVA macromolecules, greatly improving the mechanical properties of the polymer hydrogel. With excellent light absorption, heat localization and water transport capabilities, the composite hydrogel evaporator possesses a high evaporation rate (up to 3.85 kg•m−2•h−1) and a photothermal conversion efficiency of 87.6%. This hydrogel evaporator can work in a high concentration brine and during cyclic evaporation, exhibiting outstanding salt rejection performance and long-term durability. The high performance ACNTs filled hydrogel shows promising applications in solar desalination.