A biomass-based bilayer aerogel for efficient solar-driven steam production and electricity generation

Solar-driven interfacial evaporation exhibits potential for seawater desalination and sewage treatment. Over the past decade, researchers have developed various types of interfacial solar evaporators. However, there are few reports on the harvesting of intrinsic electrokinetic energy during solar-driven evaporation. In this study, an all-in-one bilayer aerogel evaporator was constructed using earth-abundant and economical cellulose and lignin as raw materials for simultaneous solar desalination and electricity generation. Owing to its unique hierarchical architecture, superior solar absorption, and outstanding structural stability, the evaporator exhibited excellent evaporation performance and salt resistance, with an evaporation rate of up to 3.9 kg m−2h−1 under 1 sun irradiation and a solar-to-vapor conversion efficiency of 95.8 % while stably exporting an output voltage of 77 mV. Furthermore, by connecting multiple evaporators in series, the evaporation system could generate sufficient fresh water to satisfy individual drinking needs, and the generated electricity could be stored in capacitors to drive small electronic devices such as light-emitting diodes. This study provides a facile and efficient solution for designing drinkable water and electricity cogeneration devices.