Fabrication of hygroscopic photothermal fibroin-based aerogels for dehumidification and solar-driven water harvesting

The high-humidity environment will make people uncomfortable and even easily causes inconvenience to people's health. Thus, various chemical or biological desiccants and air conditioners are applied for air dehumidification. However, how to recycle water resources in the process of efficient dehumidification is a meaningful problem to be solved. In the present work, solar-powered hygroscopic photothermal fibroin-based aerogels for indoor dehumidification and water harvesting were fabricated. Briefly, copper sulfide nanoparticles (CuSNPs) were synthesized using silk fibroin (SF) chains as templates, and the aerogel of SF/CuSNPs composite was obtained by freeze-drying. Subsequently, coating of hydrophilic carboxymethyl chitosan (CMCS) and calcium chloride on the photothermal aerogel was performed for moisture absorption and water recovery from the environment. The CMCS-Ca@SF aerogel exhibits encouraging water uptakes of 1.35 g/g at 90 % relative humidity (RH) for 12 h. Meanwhile, most of the absorbed water from the composite aerogel can be rapidly released within 1 h under 4-sun irradiation due to the photothermal effects of CuSNPs. The hygroscopic aerogel efficiently reduces the humidity in enclosed space and can potentially be applied for outdoor atmospheric water harvesting. Besides, the excellent antibacterial capacity endows the hygroscopic aerogel with long-term storage stability even in a high-humidity environment. This work provides an alternative to developing a convenient, effective hygroscopic aerogel for indoor dehumidification and atmospheric water harvesting.