Janus wettability Ag/polydopamine textile-based separated type solar interfacial evaporator for efficient salt-free desalination

Abstract

Solar-powered interfacial evaporation is emerging as a promising way to desalinate water and address global freshwater scarcity. The combination of a high water production rate and salt resistance capacity is highly desirable in the solar steam generation process, yet still challenging to realize. To overcome this problem, a suspended interfacial evaporator was developed using the Janus Ag/PDA textile. The Janus wettability of the Ag/PDA textile facilitated the unidirectional movement of water from the top to the bottom surface. The suspended type design of the Ag/PDA textile evaporator was capable of reducing heat dissipation to bulk water and enhancing localized heat generation significantly under solar illumination, thereby facilitating effective desalination. The steam generation rate reached an impressive 2.96 kg m^-2h⁻¹ under one sun of solar irradiation. Remarkably, no salt crystallisation was observed on the evaporator surface during a 50 h continuous experiment in a highly saline environment (15 wt% NaCl). The remarkable salt inhibition capacity was attributed to three factors, including the salt rejection effect, the salt removal effect, and the salt dissolution effect. It is hoped that this work will inspire the development of a durable solar steam evaporator.