Polymer‐decorated daikon‐based solar evaporators for efficient interfacial water evaporation

Abstract

Interface solar evaporator has been recognized as a potential device for extracting freshwater from non-potable water. Biomass like daikon is an excellent candidate for fabricating solar evaporators because of its good hydrophilia and porous structure, which facilitates water transfer and vapor release. Besides, polymers like polydopamine and polypyrrole (abbreviated as PDA and PPy, respectively) possessing wide spectrum absorption are fascinating candidates for efficient solar evaporators. Herein, PDA-decorated daikon and PPy-decorated daikon (abbreviated as PDA-DK and PPy-DK, respectively) solar evaporators have been developed for vapor production. Due to polyethylene foam can effectively concentrate the heat on the photothermal materials, under 1-solar intensity, the water vaporization rates of PDA-DK and PPy-DK are enhanced to 1.50 and 1.60 kg m−2 h−1, and the relative solar thermal efficiencies are improved by about 40%, from 49.51% and 58.65% to 89.01% and 98.97%, respectively. Thanks to the super hydrophilicity and high water storage capacity, the PPy-DK has the self-cleaning ability and can effectively desalinate seawater with a desalination rate of around 1.6 kg m−2 h−1. Moreover, both solar evaporators exhibit considerable stability in evaporation rate, with no significant changes within 15 cycles. Outdoor experiments demonstrate that these two solar evaporators are capable of desalinating saltwater and cleaning dye wastewater.