Superhydrophobic Graphene/Cellulose/Silica Aerogel with Hierarchical Structure as Superabsorbers for High Efficiency Selective Oil Absorption and Recovery

Carbon-based aerogels have been recognized as a promising 3D superabsorbent material for oil absorption due to their high absorption capacity. However, their selective absorption efficiency is limited because of their relatively low hydrophobicity. Here, we report the fabrication of a fluorinated hybrid aerogel (FHA) consisting of graphene oxide (GO), cellulose nanofibrils (CNFs), and silica nanoparticles by one-pot hydro-thermal synthesis and subsequent freeze-drying and chemical vapor deposition modification. The CNFs in FHA prevented volume shrinkage, greatly reduced the bulk density, and increased the surface area, while the GO retained its mechanical strength and the free-standing characteristic of FHA. Silica particles and CNFs created hierarchical structures on pore walls, and the grafted fluorochains reduced the surface energy. The synergistic effect of the hierarchical structure and low surface energy contributed to the excellent superhydrophobicity (water contact angle of 157) and water repellency (contact angle hysteresis less than 1) of FHA. Meanwhile, FHA maintained superoleophilicity and showed extraordinary absorption efficiency (similar to 100%) and relatively high absorption capacity (39-68 times weight gain) to various oils and chemical solvents. This high performance can be maintained in repetitive use. Furthermore, a self-driven oil collection device assembled with FHA demonstrated its diverse applications in water remediation.