Cotton fiber-based composite aerogel derived from waste biomass for high-performance solar-driven interfacial evaporation

Cellulose-based composite aerogels derived from natural fibers have attracted widespread attention in the emerging field of solar-driven interfacial evaporation to produce clean water in an eco-friendly manner. However, the complex extraction process of cellulose and the expensive photothermal materials are urgent challenges for the preparation of solar-driven interfacial evaporators, which seriously hinder real applications. In this paper, the high-performance composite aerogel-based evaporators that could be directly constructed from cotton staple fibers derived from waste cotton fabrics without the cellulose extraction process and the photothermal conversion materials produced from the carbonization of waste cotton straw were reported. With the help of excellent hydrophilicity, water conductivity, and light capturing, the evaporators achieved outstanding light absorptivity (95.6%) and stable water evaporation rate (1.96 kg·m−2·h−1) under one sun irradiation. In the long-term practical application, the obtained evaporator exhibited excellent durability and recyclability, which facilitated the continuity of the evaporation process. Furthermore, the solar-driven interfacial evaporator was employed to purify seawater and various kinds of wastewater containing methyl orange (MO), indigo (ID), and acid black (AB). Interestingly, the evaporator could realize stable power generation due to the formation of an ionic gradient during the simulated seawater desalination, with an output voltage of 139 mV under one sun irradiation. The cotton fiber-based composite aerogels designed in this study have the advantages of cleanliness and high efficiency, which occupy significant economic value and extensive application potential in the fields of actual water purification and green energy development.