Scalable and robust bilayer polymer foams for highly efficient and stable solar desalination

Solar-driven vaporization devices are often hindered by complex fabrication process, low efficiency, poor durability, and non-reusability. Herein, based on the pre-pressed melamine foam (MF), we have fabricated a scalable, low cost, and durable bilayer polymer foam for efficient and stable solar steam generation. Making use of the bilayer structure, different functions are assigned to different layers, with polypyrrole (PPy) coating pre-pressed MF (PPy layer) for light absorption and water evaporation, and bottom pre-pressed MF layer for water transport and thermal insulation. A high average evaporation rate of 1.574 kg m−2 h−1 and a superb steam generation efficiency of 90.4% under 1 sun are achieved. Bilayer foam demonstrates remarkable robustness and stability under a series of severe conditions. Bilayer foam can keep its structural stability and evaporation performance in durability tests (over 30 days, with 60 min each day), exhibiting the long-term durability, excellent antifouling property, and good reusability. We have also demonstrated the potential practicability of two simple prototype devices for solar steam generation on land and water. The low cost, large-scale, and durable solar steam generation device is promising for highly efficient and stable generating fresh water under natural sunlight conditions, which is especially attractive for remote areas that lack of fresh water supply.