Natural convection enhanced highly efficient and salt rejecting solar evaporator

Thermally localized solar evaporation provides a sustainable solution to address the water-energy nexus, which is promising for the applications in vapor generation, seawater desalination, wastewater treatment, and medical sterilization. However, salt accumulation has been identified as one of main practical challenges, which induces undesired fouling and reduces device lifetime. Here, we develop a novel confined water layer structure enabling a simultaneously highly efficient and salt rejecting solar evaporation. With high-fidelity modeling and experimental characterization of salt transport, we optimize the fluidic flow in the confined water layer. With the optimized flow field, our design is capable of salt transport without sacrificing energy efficiency. In addition, we further applied our design to the contactless solar evaporator and report a record-high efficiency. The fundamental understanding of salt transport shown in this work paves a new avenue toward the high-performance and reliable solar evaporation with low-cost and high material flexibility.