Enhanced selectivity and ultra-fast detection of NO2 gas sensor via Ag modified WO3 nanostructures for gas sensing applications

Recently, nanostructured tungsten oxide-based materials have received much attention in the field of the gas sensor due to their superior size-dependent gas adsorption and catalytic properties. Herewith, we have successfully prepared pure and Ag-doped WO3 nanostructures via a hydrothermal method. The effect of doping (Ag) in WO3 and their gas sensing properties was systematically studied. Interestingly, the Ag-2 sensor revealed the enhanced gas sensing response of 52404% @1000 ppb, which is 5-fold higher than that of the pure WO3 sample at 150 ℃. Moreover, Ag-2 sensor possessed an ultra-fast response and recovery time of 1 s and 3.5 s. Further, as-prepared sensors exhibit excellent selectivity, repeatability, and long-term stability. In addition, the DFT calculations were performed to evaluate the adsorption and charge transfer dynamics of NH3, H2S, and NO2 gas molecules on pure and Ag-doped WO3 surfaces. These results pave the new pathway to developing real-time metal oxide-based gas sensors at lower operating temperatures.