Lignin-based multi-scale cellular aerogels assembled from co-electrospun nanofibers for oil/water separation and energy storage

Fibrous aerogels have received considerable attentions owing to their high specific surface area and multifunctional applications. However, it remains a huge challenge to prepare multi-structured nanofibrous aerogels using green renewable materials. Herein, lignin-based multi-scale cellular aerogels assembled from coelectrospun nanofibers are successfully constructed. Primarily, by preoxidation of core-shell nanofibers assembled uncrosslinked aerogels, lignin-based pre-oxidized aerogels (LPA) with hierarchically natural wood-tracheidlike structures and porous cell walls are prepared. The LPA exhibits excellent hydrophobicity and high adsorptive capacity for diverse oils and organic solvents (adsorption capacity up to 103 g g-1). Furthermore, benefiting from the existence of nitrogen functional groups, LPA can be carbonized to nitrogen-doped carbon aerogels (NCA). The obtained NCA not only inherits cellular structures from LPA but also creates abundant interior porosity of nanofibers due to the vacancy left by degradation of polymer. The NCA is used as electrodes materials of supercapacitors, the multi-channel structures at micro/nano scales of NCA can serve as "highway" for fast transportation of ions and electrons. The symmetrical supercapacitor assembled from it delivers a high energy density of 32 Wh kg-1. Our study provides a new insight for designing and synthesizing biomass-based multifunctional materials through a low carbon footprint manner.