Recent advances in thermally localized solar evaporation show promise for various applications, but salt accumulation is a major obstacle. This study demonstrates highly efficient (>80% solar-to-vapor conversion efficiency) and salt-rejecting (20 weight % salinity) solar evaporation using a wick-free confined water layer. Mechanistic modeling and experiments reveal that natural convection accelerates salt rejection with minimal heat loss. The approach is broadly applicable, improving efficiency when integrated with contactless solar evaporators. This work elucidates salt transport fundamentals and offers a low-cost strategy for high-performance solar evaporation.

Lenan Zhang, Xiangyu Li, Yang Zhong, Arny Leroy, Zhenyuan Xu, Lin Zhao, Evelyn N. Wang