Rapid-Response Flexible Gas Sensor Based on Porous MXene/In₂O₃ Composites with Integrated Heating for NO₂ Detection

Accurate and rapid detection of NO₂ is critical for environmental monitoring and human health protection, yet conventional gas sensors often exhibit slow response and recovery, high power consumption due to elevated operating temperatures, and limited integration, typically relying on external heating rather than on-chip thermal control. Here, we demonstrate a flexible NO₂ sensor based on a porous MXene (PM)/In₂O₃ composite, featuring a hierarchical porous architecture and fully integrated design for low-temperature operation. The sensor achieves an ultrafast dynamic response, with response and recovery times of 1.3 s and 3.5 s, enabling real-time detection of transient NO₂ exposure. Its high specific surface area (91.3 m²/g) facilitates abundant active sites and rapid gas adsorption and diffusion, enhancing both sensitivity and response speed. Moreover, the integrated interdigital and heating electrodes on a single flexible substrate minimize power consumption and support miniaturized, chip-compatible sensing platforms. The device exhibits a high response of 42.41 at 100 ppm NO₂, together with excellent selectivity, repeatability, and mechanical stability, offering a promising strategy for next-generation flexible and intelligent gas sensors with ultrafast, energy-efficient, and reliable performance.