Abstract
The application of metal oxide-based sensors for the detection of volatile organic compounds is restricted because of their high operating temperatures and poor gas sensing selectivity. Driven by this fact, we report the low operating temperature and high performance of C(3)H(7)OH and C(2)H(5)OH sensors. The sensors comprising SnO(2) hollow spheres, nanoparticles, nanorods, and fishbones with tunable morphologies were synthesized with a simple hydrothermal one-pot method. The SnO(2) hollow spheres demonstrated the highest sensing response (resistance ratio of 20) toward C(3)H(7)OH at low operating temperatures (75 °C) compared to other tested interference vapors and gases, such as C(3)H(5)O, C(2)H(5)OH, CO, NH(3), CH(4), and NO(2). This improved response can be associated with the higher surface area and intrinsic point defects. At a higher operating temperature of 150 °C, a response of 28 was witnessed for SnO(2) nanorods. A response of 59 was observed for SnO(2) nanoparticle-based sensor toward C(2)H(5)OH at 150 °C. This variation in the optimal temperature with respect to variations in the sensor morphology implies that the vapor selectivity and sensitivity are morphology-dependent. The relation between the intrinsic sensing performance and vapor selectivity originated from the nonstoichiometry of SnO(2), which resulted in excess oxygen vacancies (V(O)) and higher surface areas. This characteristic played a vital role in the enhancement of the target gas absorptivity and the charge transfer capability of SnO(2) hollow sphere-based sensor.