The pervasive issue of nitrogen dioxide (NO2) as a hazardous air pollutant requires the development of high-performance gas sensors with high sensitivity, long-term stability, and low-temperature operation. While metal oxide semiconductors (MOS), such as In2O3 and ZnO, have been extensively investigated for this purpose, their practical application is often limited by the requirement for high operating temperatures and insufficient sensitivity to parts-per-billion (ppb) concentrations. Herein, we report a hierarchical ternary hybrid material, In2O3@ZnO@PPy, specifically designed for near-room temperature and light-assisted NO2 detection. The collective synergistic effects arising from the hierarchical architecture, inter-semiconductor heterojunctions, and conductive polymer integration enable the In2O3@ZnO@PPy sensor to exhibit exceptional sensitivity to NO2 at a low operating temperature of only 70 °C under blue-light excitation. The response value to 10 ppm NO2 is as high as 221.4. The optimized sensor demonstrates an ultralow limit of detection of 50 ppb. More importantly, the hybrid exhibits remarkable humidity tolerance, maintaining high sensing performance even at 80% relative humidity. Surface wettability analysis suggests that PPy incorporation modulates the interfacial interaction with water molecules, which helps alleviate humidity-induced interference during NO2 detection. The device further exhibits excellent repeatability, long-term stability, and strong selectivity against common interferents. These findings establish a light-assisted strategy for ppb-level gas sensing and provide a generalizable route for designing multifunctional hybrid materials for environmental monitoring and health diagnostics.
Li et al. (Fri,) studied this question.