Silk fibroin/carbon nanofiber composite aerogel for efficient and stable solar steam generation

Abstract

The development of bio-based aerogel is an important solar evaporation issue owing to its environmental protection, sustainable water transportation, and intrinsic thermal management properties. Herein, silk fibroin (SF)/carbon nanofiber (CN) composite aerogel (SCNA) was prepared by incorporating carbonized electrospun polyacrylonitrile (PAN) nanofibers into SF aqueous solution and then performing a freeze-drying process. The SCNA with optimized CN loading demonstrated outstanding solar absorbing capacity (99.89%) across the whole spectrum due to the synergy between the functional solar absorbing CN material and the SF skeleton (71.64%). With high porosity, the SF skeleton can encapsulate the CN, transport water, and suppress heat loss in solar evaporation. As a result, high evaporation rates were achieved for pure water (1.46 kg m−2 h−1), 3.5% salty water (1.42 kg m−2 h−1), and actual dyeing wastewater (1.43 kg m−2 h−1). Besides, the SCNA could be reused more than ten times without performance degradation, assuring long-term efficient solar steam generation. Therefore, this work will stimulate more research on the use of biomass materials for solar evaporation, especially silk-based aerogel.