Multi-scale structure synergistic strategy: A transpiration inspired hierarchical aerogel evaporator for highly efficient solar-driven clean water production

Abstract

Solar-driven evaporation has been recognized as a great candidate for freshwater production and has received growing interest as a practical approach to cope with global water scarcity and energy crisis. However, evaporation design with low heat loss, high photothermal conversion and sustainable water supply is still challenging for practical application. In this work, inspired by the transpiration of plants, we reported a high photothermal chitosan (CS)/cellulose nanofiber (CNF) based aerogel evaporator with a hierarchical light-absorbing structure by introducing PPy cross-linked network as light-absorber, which realize the synergistic integration of light absorption, heat location and water transportation. The integration of microstructure for light-absorbing and macroporous structure inside aerogel leads to strong water transportation via capillary action and vapor escape. Moreover, the hierarchical porous structure contributes to the low sunlight reflection (under 10%). Interestingly, the integrated evaporation system not only shows high efficiency (94.3%) and evaporation rate (1.67 kg m−2 h−1) but also achieves satisfactorily self-disinfection. We believed that this work could provide new insights into the development of solar-driven low-energy water purification/harvesting and sustainable cleaner production.