Facile Microwave-Assisted Surfactant Free Hydrothermal Synthesis of Nanoporous SnO₂ Nanowire Bundles for Alcohol Detection

Nanoporous SnO 2 nanowire bundles, along with SnO 2 aggregated particles, were synthesized by a simple, rapid, and surfactant-free microwave-assisted hydrothermal approach at 120°C and they were separated through a filtration process. The growth process of these materials has been explained based on self-assembled oriented growth and the redox process, respectively. Scanning electron microscopy revealed that the diameters of the nanowires are in the range of 100 to 400 nm. The obtained specific surface area of nanoporous SnO 2 nanowire bundles shows a larger value of 41.517 m 2 /g than those of the SnO 2 aggregated particles and the mixture. Gas sensing measurements toward alcohols, such as methanol, ethanol, and 2-propanol, show that the nanoporous SnO 2 nanowire bundles exhibited the highest response values ( R a / R g ) of 5.13, 8.57, and 6.80 at a 100 ppm concentration with their respective operating temperatures. The variations in the fitted response/recovery curves and related response/recovery times to different alcohols at different operating temperatures show that the nanoporous SnO 2 nanowire bundles possess different adsorption/desorption properties for these alcohols over the surface. This leads to different optimum operating temperatures of 280°C, 240°C, and 220°C for methanol, ethanol, and 2-propanol, respectively. The device stability confirms its suitability for alcohol detection in practical applications.