Time-Frequency Domain NO₂-Humidity Sensor with Full-Range Tolerance Based on Pt Single-Atom Sensitized Nb₂CT_x...

Real-time in situ detection of NO₂ is crucial for ensuring industrial safety and healthcare. However, conventional gas sensors face challenges from environmental humidity interference, limiting their reliability in practical applications. This study presents a dual-mode, full-range NO₂-humidity sensing platform based on Pt single-atom-sensitized Nb₂CT_x nanosheets (Pt SA-Nb₂CT_x) integrated with TPU fiber mats (Pt SA-Nb₂CT_x@TPU). Combining resistive gas sensing and capacitive humidity sensing within a single device, this platform enables simultaneous NO₂ and humidity detection with full-range humidity tolerance. The uniformly dispersed Pt single-atoms on the Nb₂CT_x nanosheets catalyze oxygen molecule dissociation and provide additional surface-active adsorption sites, achieving a 9.1-fold improvement in resistance response to 5 ppm NO₂ and a 25.7-fold increase in capacitance response at 95% relative humidity. Importantly, the unaffected capacitive response allows precise calibration of NO₂ concentration using resistance and capacitance, ensuring accurate NO₂ detection across diverse and fluctuating humidity. Leveraging time- and frequency-domain NO₂-humidity sensing capability, the Pt SA-Nb₂CT_x@TPU sensor is successfully integrated into self-designed functional modules to realize humidity tracking, industrial NO₂ concentration alarming in full-humidity range as well as asthma prevention and alarm applications. This study offers a novel solution for humidity-compensated NO₂ detection, advancing the applicability of gas sensors in complex and dynamic environments.