Fibrous TiO₂ gas sensors produced by electrospinning

Gas sensors produced by electrospinning demonstrate high performance in terms of sensitivity, reversibility, response and recovery time. These merits were attributed to their nanostructured fibrous morphology with high surface area and small grain size. This hypothesis is examined in this work by comparing the gas sensing properties of fibrous TiO₂ gas sensors obtained by electrospinning. Sensors with markedly different grain size and specific surface area, obtained by changing process parameters such as the polymer solution (PVAc or PMMA) and calcination temperature (450 or 750 °C) displayed rather ambiguous correlation between the morphology and gas sensitivity. The sensors that were calcined at 750 °C were found to be more sensitive than their 450 °C calcined counterparts, for the most part, despite having larger grain size and smaller specific surface area. This unexpected result questions the dogma regarding the correlation between sensor morphology and gas sensitivity, suggesting that another effect might be at play.