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Abstract

Monitoring toxic air pollutants, including H₂S and N₂O, is crucial for public and environmental health. Conventional thermally activated chemiresistive gas sensors are limited by high temperature and power requirements, bulkiness, and unfeasibility of operation in environments with flammable gases. To address these issues, UV-activated CuO nanosheets and Sr-doped SnO₂ sensing layers were developed for measuring H₂S and N₂O at room temperature on a low-power, miniature platform, offering a more efficient and practical solution. For H₂S detection, CuO nanosheets were synthesized via hydrothermal methods and their plate-like morphology confirmed by SEM analysis. The CuO nanosheets, activated under 275 nm UV-LED, demonstrated sensitive measurement of H₂S in the 1–100 ppm range, with rapid response and recovery times of 80 s and 600 s, respectively, for concentrations above 50 ppm. The nanosheet morphology coupled with UV irradiation enhanced sensor sensitivity and stability, and broadened the detection range compared to nanoparticles. The sensor exhibited excellent selectivity for H₂S, displaying significantly higher sensitivity to 1 ppm of H₂S compared to 10 and 50 ppm of common interfering gases, such as N₂O, NO₂, CH₄, CO, and NH₃. CuO nanosheets exposed to varying humidity levels showed decreased sensitivity as humidity increased. For N₂O detection, Sr-doped SnO₂ was synthesized through co-precipitation and measured 30–100 ppm N₂O, a range critical for workplace safety. The composition of the sensingiv layer was investigated, revealing that optimal gas-sensing performance occurred at 3 wt. % Sr doping. The sensor responded to N₂O and recovered to baseline resistance in 130 and 200 seconds, respectively, enabling real-time detection and timely hazard alerts for workers. A key advantage of using a UV-LED energy source is the ability to tune its operational parameters (irradiance and wavelength) to enhance gas-sensing performance. The choice of wavelength influenced sensor reproducibility and stability under N₂O exposure. Optimal low irradiance conditions of 11 µW/cm² demonstrated high sensitivity, highlighting the low power consumption of UV-activated sensors. By leveraging nanotechnology and UV-LED technology, we developed highly sensitive and selective gas sensors with fast response and recovery times at room temperature on a low powered and miniatured platform, facilitating integration into smart devices.