Rapid and facile fabrication of hierarchically porous graphene aerogel for oil-water separation and piezoresistive sensing applications

Graphene aerogel (GA) holds great potentials for versatile applications, for example, oil-water separation and piezoresistive sensing. However, GA is generally prepared via time-consuming and complicated methods. Herein, a rapid and facile approach has been proposed to fabricate GA by a two-step reduction method, i.e., hydrothermal reduction by thiourea at a mild temperature of 95 °C for 30 min followed by microwave treatment for several seconds, c.a., 4–12 s. GA was partially reduced in the first step and self-assembled into a 3D scaffold which is much more receptive to microwaves and promotes the second complete reduction by microwave treatment. By tuning the microwaving time, the GA microwaved for 10 s, that is, MGA-10 exhibits hierarchically porous microstructure, ultra-low density, and super compressibility. MGA-10 can be used as a recyclable absorbent with high absorption capacities (223 ∼ 430 g/g) towards various oils and organic solvents. Meanwhile, the high sensitivity of the electric resistance to the compressive strain enables MGA-10 promising for pressure sensor applications. The MGA-10 sensor demonstrates high sensitivity (1.112 kPa⁻¹ at a pressure range of 0 ∼ 0.3 kPa) and excellent stability (>3000 cycles). This fabrication route paves the way to efficiently prepare highly compressible graphene aerogels for versatile applications.