Sun-powered sponge turns saltwater fresh, no electricity needed

Researchers at The Hong Kong Polytechnic University have developed a novel 3D-printed aerogel material that can desalinate seawater using only sunlight, without requiring electricity. This sponge-like aerogel, made from carbon nanotubes and cellulose nanofibers, contains microscopic air pockets and uniform vertical pores about 20 micrometers wide, which efficiently facilitate water evaporation while leaving salt behind. The material’s desalination efficiency remains consistent regardless of its size, making it scalable for larger applications. In practical outdoor tests, the aerogel was placed in seawater under a curved plastic cover, where sunlight heated the material to evaporate water. The vapor condensed on the plastic lid and was collected as fresh water, producing approximately three tablespoons of drinkable water after six hours of natural sunlight. This low-energy, sustainable desalination method offers a promising solution to global water scarcity, especially as conventional desalination plants typically require significant energy input. The research, published in ACS Energy Letters, highlights the potential for scalable, energy