Time-Frequency Domain NO<sub>2</sub>-Humidity Sensor with Full-Range Tolerance Based on Pt Single-Atom Sensitized Nb<sub>2</sub>CT<sub>x</sub> Nanosheets.

Kan, Zitong; Hu, Wenbo; Hu, Chencheng; Shi, Fangyu; Yang, Long; Zhou, Qingqing; Zhang, Wei; Qi, Yu et al. · Adv Mater · 2025

basic_science · Level V

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Abstract

Real-time in situ detection of NO<sub>2</sub> 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 NO<sub>2</sub>-humidity sensing platform based on Pt single-atom-sensitized Nb<sub>2</sub>CT<sub>x</sub> nanosheets (Pt SA-Nb<sub>2</sub>CT<sub>x</sub>) integrated with TPU fiber mats (Pt SA-Nb<sub>2</sub>CT<sub>x</sub>@TPU). Combining resistive gas sensing and capacitive humidity sensing within a single device, this platform enables simultaneous NO<sub>2</sub> and humidity detection with full-range humidity tolerance. The uniformly dispersed Pt single-atoms on the Nb<sub>2</sub>CT<sub>x</sub> nanosheets catalyze oxygen molecule dissociation and provide additional surface-active adsorption sites, achieving a 9.1-fold improvement in resistance response to 5 ppm NO<sub>2</sub> and a 25.7-fold increase in capacitance response at 95% relative humidity. Importantly, the unaffected capacitive response allows precise calibration of NO<sub>2</sub> concentration using resistance and capacitance, ensuring accurate NO<sub>2</sub> detection across diverse and fluctuating humidity. Leveraging time- and frequency-domain NO<sub>2</sub>-humidity sensing capability, the Pt SA-Nb<sub>2</sub>CT<sub>x</sub>@TPU sensor is successfully integrated into self-designed functional modules to realize humidity tracking, industrial NO<sub>2</sub> concentration alarming in full-humidity range as well as asthma prevention and alarm applications. This study offers a novel solution for humidity-compensated NO<sub>2</sub> detection, advancing the applicability of gas sensors in complex and dynamic environments.