Defect manipulation of WO3 nanostructures by yttrium for ultra-sensitive and highly selective NO2 detection

Abstract

Nanostructured transition metal oxides have gained much attention in gas sensing applications due to their superior size-dependent adsorption and catalytic properties. Among them, WO3 based nanostructured thin films exhibit relatively high sensitivity towards toxic gases such as CO, NO2, NH3, and H2S, which makes them promising materials for gas sensing applications. Herein, we have attempted to prepare pure and yttrium-doped WO3 nanoplates by one-step hydrothermal method and their gas sensing performance was studied. The selectivity of the fabricated device was studied against NH3, NO2, and H2S gases. Pure and Y-doped samples exhibited an excellent selectivity towards NO2. The gas sensitivity, response time, and recovery time have been significantly enhanced for the Y-doped samples compared to the pure sample. Interestingly, the Y-doped sample (3 mM) exhibits an excellent response towards 20 ppm of NO2, which is comparatively 94- fold higher than pure WO3. The sample exhibited a short response T90 ~ 7 s and recovery time T10 ~ 38 s. The Y-2 sensor showed excellent repeatability and long-term stability. This is due to oxygen vacancy defects and the high surface area of the material. The enhancement in gas sensing performance has been explained by the gas sensing mechanism and work function measurement. The Y-doped WO3 nanostructures provide a new pathway for improving the performance of transition metal oxide-based gas sensors.