Assembly of Janus complex with low-cost and salt rejection for solar-thermal water evaporation

Interfacial solar-thermal water evaporation (STWE) shows considerable potential in terms of harvesting freshwater from the ocean; thereinto, the design of an efficient floatable material with low-cost and salt deposition resistance is always one of the most concerned issues. In this work, we prepared an economical Janus complex for STWE by assembling commercial carbon nanotubes and porous cotton fiber paper, functionalized by silanization and combination of polyelectrolyte. Because of the synergy of efficient photothermal conversion, localized hot layer and fast transmission of water and vapor, the Janus complex displayed a superior evaporation rate of 3.443 kg m−2 h−1 under 5 suns (5 kW m−2) in saltwater. Moreover, almost no salt was detected in the used Janus complex, and the salt deposition was rejected at the source due to the strong ionic strength of polyelectrolyte. These results indicated that the Janus complex has potential applications for water purification.