Self-powered aligned porous superhydrophobic sponge for selective and efficient absorption of highly viscous spilled oil.

Crude oil spills have caused catastrophic damage to marine ecosystems and become a global challenge. Although various liquid absorption materials have been developed, manual operations such as pumping and electric heating are still required in the face of highly viscous spilled oils. Efficient and autonomous crude oil spill cleanup methods are urgently needed. Here, inspired by the unidirectional microstructure of tree xylem, we report a sponge (SPC-Sponge), which combines superhydrophobic property and aligned porous structures, prepared from a ternary suspension (hydrophobic silica nanoparticles, polyurethane, and cellulose nanofibers) by single-step directional freeze casting. SPC-Sponge not only effectively overcome the limitations of traditional synthetic modification methods on the shape and size of porous sponge materials, but also has excellent oil-water selection function, liquid absorption speed, and liquid absorption capacity compared with common porous materials. Moreover, the sponge can self-absorb highly viscous crude oil of around 80,000 mPa‧s on seawater without external energy and human intervention. By adding multi-walled carbon nanotubes, the sponge can implement in-situ solar heating of crude oil, and the absorption speed is further improved. Given its unique structural design and superwetting property, this SPC-Sponge provides an efficient remediation approach for viscous oil spills.