Three-dimensional hierarchical and superhydrophobic graphene gas sensor with good immunity to humidity

摘要

Superhydrophobic reduced graphene oxide (RGO) with unique 3D hierarchical structures is synthesized by exploiting one-step spark plasma sintering (SPS) within 60 s for high-performance NO₂ detection. The effective removal of oxygenated groups and generation of 3D hierarchical structures in SPS render the RGO superhydrophobic. The superhydrophobicity makes the fabricated RGO sensor exceptionally immune to high relative humidity (RH). Specifically, the RGO sensor exhibits a response degradation less than 5.5% to 1 ppm NO₂ when the RH increases from 0% to 70%. Importantly, an integrated microheater array is employed to remarkably activate the RGO-based NO₂ sensor, boosting the sensitivity. Consequently, the NO₂ sensor displays a high sensitivity (25.5 ppm^-1) and an extremely low limit of detection (9.1 ppb). The boosted NO₂ sensing performance is attributed to superhydrophobicity, 3D hierarchical structures with high specific surface area (850 m²/g), abundant defect sites and thermal activation with microheaters.