Anisotropic Free-Standing Aerogels Based on Graphene/Silk for Pressure Sensing and Efficient Adsorption.

Compressible, conductive, ultralight, and superhydrophobic graphene aerogels (GAs) are promising for wearable electronics and adsorption applications. However, the unsatisfactory sensing performances and lack of multiscale structural regulation still impede the development of multifunctional GAs. Herein, a multifunctional aerogel based on graphene/silk is reported─a highly ordered three-dimensional (3D) reduced graphene oxide (rGO) conductive network is established by an alkali-induced hydrothermal self-assembly strategy, while silk fibroin (SF) bound to graphene oxide (GO) by electrostatic interactions is uniformly distributed throughout the network. The ultralight rGO/SF aerogel (GSA) has the property that its resistance varies with compression, so it can be used for flexible pressure sensors. A GSA-based sensor can detect compressive stresses down to 0.35 kPa and has a response time of 0.55 s and a recovery time of 0.58 s. It has a good linear response from 0.5 to 30 kPa with sensitivities of 0.54 kPa (0.5-4 kPa) and 0.21 kPa (4-30 kPa), respectively. The GSA-based sensor also has excellent durability, remaining stable after 12,000 cycles. As proof of concept, its applications for health monitoring, speech recognition, and motion capture are shown. Furthermore, the carbonized rGO/SF aerogels (C-GSAs) with superhydrophobicity can adsorb various organic substances (146.7-278.8 g/g) and achieve oil-water separation.