Fabrication of a bilayer structural carbon-based hydrogel material with excellent energy conversion efficiency

Solar steam generation is a promising technology to solve the freshwater crisis. With the continuous research of this technology, apart from developing efficient photothermal conversion materials that can increase the evaporation rate, it is found that a reasonable structural design can also achieve this goal. In this study, we fabricated a bilayer structural carbon-based hydrogel composite material. The composite material achieved a maximum evaporation rate of 2.19 kg m−2 h−1 and an energy conversion efficiency of 93.7% under one sun (1 kW m−2) irradiation, which is superior to most evaporators. Moreover, the fabricated composite material exhibited outstanding seawater desalination performance and durability, expanding the range of its practical applicability. In addition, the scalability and portability allow the composite to easily withstand various complex environments, and its production cost is low, making it easily implemented on a large scale in economically backward areas. This study provides valuable information for designing and producing composite-structure hydrogel evaporators.