Scalable Superhydrophilic Solar Evaporators for Long‐Term Stable Desalination, Fresh Water Collection and Salt Collection by Vertical Salt Deposition

Abstract

Solar‐driven interfacial evaporation (SIE) is very promising to solve the issue of fresh water shortage, however, poor salt resistance severely hinders long‐term stable SIE and fresh water collection. Here, we report design of superhydrophilic solar evaporators for long‐term stable desalination, fresh water collection and salt collection by vertical salt deposition. The evaporators are prepared by sequentially deposition of silicone nanofilaments, polypyrrole and Au nanoparticles on a polyester fabric composed of microfibers. The evaporators feature excellent photothermal effect and ultrafast water transport, due to their unique micro‐/nanostructure and superhydrophilicity. As a result, during SIE the salt gradually deposits vertically rather than occupies larger area on the evaporators. Consequently, long‐term stable SIE with high evaporation rates of 2.4‐2.1 kg m‐2 h‐1 for 3.5‐20 wt% brine in continuous 10 h is achieved under 1 sun illumination. Meanwhile, the loosely deposited salt can be easily collected, realizing zero brine discharge. Moreover, scalable preparation of the evaporator is achieved, which exhibits efficient collection of high quality fresh water (10.08 kg m‐2 in 8 h) via SIE desalination under weak natural sunlight (0.46~0.66 sun). This strategy sheds a new light on the design of high‐performance solar evaporators and their real‐world fresh water collection.