Sulfur dioxide gas sensor based on vanadium oxide doped TiO2 nanopaper

The gas sensor based on TiO2 nanomaterials is promising for both industry and daily life because of its simple fabrication, low cost, high sensitivity, and easy application to micro-devices. However, its selectivity is relatively low and strongly influenced by the environment, thus limiting its practical application. In this work, we prepared TiO2 nanopaper by methods of hydrothermal synthesis and conventional paper preparation. To improve the selectivity, we added V2O5 by immersing the as-prepared nanopaper in an ammonium metavanadate (NH4VO3) solution evenly dispersed in ethanol. Nanopaper is a random array of long nanowires and nanofibers, which retains its shape and structure at high temperature, unlike pure nanowires, due to its high porosity and mechanical stability. V2O5 leads to a selective sensing performance with high catalytic activity for SO2 gas. The surface structure of the sensing material and its porosity were characterized by SEM, XRD, XPS. The improved sensing material exhibited a high response of about 22.6 for 100 ppm SO2 and a fast response and recovery of 9 s and 14 s, respectively. It also exhibited good reproducibility and selectivity in other interfering gases. Furthermore, the long-term sensing performance in the atmospheric environment was maintained for about 50 days.