Transition Metal-Engineered Oxygen Vacancy-Mediated Al-Doped WO₃ Nanoplates for NO₂ Detection

The pursuit of exceptional performance stands as a perpetual focus in gas sensor research. Given the intricacies of response and recovery processes, achieving selectivity, high response, and swift response/recovery time remains a challenging endeavor in the atmospheric environment. Chemiresistive metal oxide semiconductor gas sensors find extensive use, operating effectively at moderate temperatures, for detecting toxic gases such as nitrogen dioxide (NO 2 ). The gas-sensing performance of pristine and Al-doped tungsten trioxide (WO 3 ) has been comprehensively examined, and the findings demonstrate that an NO 2 sensor based on hierarchical nanoplates exhibits an impressive and well-rounded gas sensitivity performance profile. This includes a low limit of detection of 4.7 ppm, a broad detection range spanning from 2.5 to 10 ppm (with a sensing performance of 9683%), exceptional selectivity, rapid response and recovery characteristics of 17 s/72 s for an AW3 sensor, outstanding repeatability, as well as better long-term stability. The remarkable gas-sensing performance can be attributed to the presence of defects in the oxygen vacancy structure. This effectively enhances the surface reactivity of monoclinic WO 3 nanoplates, contributing to their high sensitivity and broad-range sensing performance. Consequently, this study showcases significant potential for the application of environmental NO 2 monitoring.