Solar interfacial evaporator with three-dimensional architecture for seawater desalination

Solar-driven interfacial evaporation is a promising desalination technology to alleviate global water scarcity. However, the evaporation rate and long-term stability are still the key constraints on the generation of solar steam. Herein, we proposed the fabrication of a specific three-dimensional (3D) evaporator featured with multi-surface evaporation, which was realized by modifying basalt fiber with photothermal polypyrrole. The microstructure of the evaporator ensured all-around light capture capability. In view of the macrostructure, the fiber-based evaporator greatly enhanced the water transportation and suppress the heat conduction loss, consequently, an evaporation rate as high as 3.61 kg/m2/h was achieved under one sun irradiation, and this was well beyond 179 % of the input solar energy limit. The unique 3D interconnected water transport channels ensured a steady water supply for desalination and facilitated the self-cleaning behavior of the evaporator. The Marangoni effect-driven salt rejection was proposed to interpret this observation and the results were further verified by a theoretical simulation. The concept of 3D solar evaporator design makes it possible to achieve efficient solar desalination while free of suffering salt blockage, which is expected to resolve difficult problems in the desalination industry by offering a scalable, efficient, and sustainable solution to the global demand for freshwater.