All-in-one chitosan-based aerogel with a semi-clad structure for solar-driven interfacial evaporation

Solar-driven interfacial water evaporation is a promising technique for recovering clean fresh water and alleviating water scarcity. In this work, an all-in-one chitosan-based composite aerogel with a highly porous semiclad structure was fabricated. In the process of interfacial water evaporation, the hydrophilic outer layer of the aerogel efficiently transported water to the upper surface through two-dimensional transport channels. Simultaneously, it rapidly converted absorbed sunlight into heat, demonstrating excellent photothermal conversion capabilities for efficient water evaporation. The hydrophobic inner core enabled the aerogel to float stably on the water surface, and had a low thermal conductivity to reduce heat dissipation into the water body. Under 1 sun illumination (1 kW m-2), the composite aerogel showed an evaporation rate of up to 1.547 kg m- 2 h-1, corresponding to an evaporation efficiency of 91.47 %. Notably, the composite aerogel demonstrated high stability and recyclability in desalination and heavy metal wastewater treatment, which had great potential in recovering both clean water and heavy metal salts. The evaporator with a semi-clad structure had practical applications in solar desalination and sewage treatment due to its stable and efficient evaporation performance and simple preparation method.