Naturally dried superelastic bioinspired graphene aerogel for pressure/stretch sensing and separation

Many practical applications of graphene require the assembly of multiple graphene nanosheets into a macroscopic aerogel. It is essential that these graphene aerogels can retain their structural integrity when undergoing large deformations. However, it is still a great challenge to achieve large-scale, deformable, and fatigue-resistant bioinspired graphene aerogels under natural conditions. Here, we demonstrated that the combination of freeze-casting technique and natural drying led to the formation of superelastic graphene aerogels, thus overcoming the conventional lyophilization process from the requirement of special equipment. Mimicking the architecture of wood, the resultant graphene aerogel achieved rapid recovery and small energy dissipation after compression cycles, even under 90% compressive strain. In particular, this graphene aerogel can maintain structural integrity after more than 1000 cycles at 70% compressive strain, due to its unique bionic structure which processes a high energy absorption capacity. Furthermore, this graphene aerogel with exceptional mechanical performance, as well as its high conductivity and hydrophobicity, presents excellent piezoresistive sensing, stretch-release cyclic rGO/silicone composite sensing and oil-water separation properties. The successful synthesis of naturally dried superelastic graphene aerogels is expected to be applied in flexible sensors and clean-up of organic pollution or oil spills.