Transition Metal-Engineered\nOxygen Vacancy-Mediated\nAl-Doped WO<sub>3</sub> Nanoplates for NO<sub>2</sub> Detection

The\npursuit of exceptional performance stands as a perpetual focus\nin gas sensor research. Given the intricacies of response and recovery\nprocesses, achieving selectivity, high response, and swift response/recovery\ntime remains a challenging endeavor in the atmospheric environment.\nChemiresistive metal oxide semiconductor gas sensors find extensive\nuse, operating effectively at moderate temperatures, for detecting\ntoxic gases such as nitrogen dioxide (NO<sub>2</sub>). The gas-sensing\nperformance of pristine and Al-doped tungsten trioxide (WO<sub>3</sub>) has been comprehensively examined, and the findings demonstrate\nthat an NO<sub>2</sub> sensor based on hierarchical nanoplates exhibits\nan impressive and well-rounded gas sensitivity performance profile.\nThis includes a low limit of detection of 4.7 ppm, a broad detection\nrange spanning from 2.5 to 10 ppm (with a sensing performance of 9683%),\nexceptional selectivity, rapid response and recovery characteristics\nof 17 s/72 s for an AW3 sensor, outstanding repeatability, as well\nas better long-term stability. The remarkable gas-sensing performance\ncan be attributed to the presence of defects in the oxygen vacancy\nstructure. This effectively enhances the surface reactivity of monoclinic\nWO<sub>3</sub> nanoplates, contributing to their high sensitivity\nand broad-range sensing performance. Consequently, this study showcases\nsignificant potential for the application of environmental NO<sub>2</sub> monitoring.