Superhydrophobic/Superhydrophilic Janus Evaporator for Extreme High Salt-Resistance Solar Desalination by an Integrated 3D Printing Method

The emerging solar desalination technology has incomparable advantages for providing a clean water solution. However, the issue of salt accumulation on the solar evaporator tops during the steam generation leads to a considerable decrease in the evaporation rate. Herein, we demonstrate a superhydrophobic/superhydrophilic Janus evaporator that enables a stable solar evaporation even in saturated brine. Our Janus solar evaporator with a superhydrophobic top and a superhydrophilic bottom has been manufactured integrally, allowing for a fast steam evaporation without the impediment of the accumulated salt residues. The superhydrophobic top changes the water passageway from the center toward the edges while it allows for the vertical transport of both solar thermo and evaporated steams. Salt residues would only be deposited at the edges of the superhydrophilic bottom, allowing for a long-term stability of the evaporator for a continuous (>50 h) solar evaporation in saturated brine, which is record-breaking for salt-resistant solar evaporators. With stable and efficient evaporation performance out of high-salinity brine, this work provides a fascinating avenue for the desalination of seawater in a salt-resistant and efficient manner.