Synthesis of 2D Porous Indium Oxide Nanosheets for Fabrication of High‐Performance Flexible Gas Sensors

Flexible gas sensing devices have attracted a growing research interest in recent years due to their potential applications in various fields such as wearable electronics. Porous 2D metal oxide semiconductors (2D MOSs) with superior electrical and catalytic characteristics are deemed as promising materials for flexible gas sensors, especially for low-concentration gas detection; however, the synthesis of high-quality 2D MOSs remains challenging. In this study, 2D porous In₂O₃ nanosheets with a high specific surface area (85.9 m²/g) and a thickness of 4.0 nm are synthesized via a scalable micro-explosion assisted caramelization reaction. The synthesis parameters affecting the formation of 2D porous metal oxide nanostructures are systematically studied, and a proposed growth mechanism is dominated by generating the sacrificial 2D carbon intermediate templates. Furthermore, flexible gas sensors are fabricated by depositing 2D porous In₂O₃ nanosheets on polyimide substrates, which exhibit outstanding sensing performance with high sensitivity toward trace hydrogen sulfide (response value of 17.3 for 250 ppb) at 37 °C, excellent selectivity, and high stability. The sensor is further integrated into a wearable, flexible wireless sensing device, showing good reliability and great potential in detecting trace hydrogen sulfide in practical applications.