Synergistic Enhancement of NO2 Sensing via Pd-Sensitized Oxygen Vacancy Engineering in WO3 Nanoplates

The strategic integration of metal catalysts with atomic defects in functional materials offers a promising pathway to tailor desired properties. In this study, we demonstrate a high-performance NO₂ gas sensor utilizing Pd-sensitized, oxygen vacancy-rich WO₃ nanoplates. Pd nanoparticles were precisely deposited on WO₃ via atomic layer deposition (ALD), which not only enhanced the oxygen vacancy (O_v) concentration but also optimized the electronic structure of the material. The resulting Pd-WO₃-O_v sensor exhibited a significantly improved response of 84.57 to 10 ppm of NO₂─3.5 times higher than pristine WO₃. The synergistic interplay between Pd catalysts and oxygen vacancies was found to simultaneously lower the operating temperature and amplify both the sensitivity and response speed. Density functional theory (DFT) calculations further confirmed that oxygen vacancies facilitate robust Pd–WO₃ interactions, elucidating the mechanism behind the enhanced performance. This work provides a novel design strategy for developing advanced gas sensors through defect and catalyst engineering.