Highly reproducible synthesis of very large-scale tin oxide nanowires used for screen-printed gas sensor

A truly simple procedure was presented for highly reproducible synthesis of very large-scale SnO2 nanowires (NWs) on silicon and alumina substrates. The growth involves thermally evaporating SnO powder in a tube furnace with temperature, pressure, and O2 gas-flow controlled to 960 °C, 0.5–5 Torr, and 0.4–0.6 sccm, respectively. The scanning- and transmission-electron-microscopic studies show that the diameter and length of the nanowires vary from 50 to 150 nm and 1 to 10 μm, respectively.As-synthesized SnO2 NWs on alumina substrates were used to fabricate gas sensor by screen-printing method. A good ohmic contact of the screen-printed NWs sensor was obtained. Randomly selected gas-sensor devices were tested with various gases such as C2H5OH, CH3COCH3, C3H8, CO, and H2 for studying gas-sensing properties. The results reveal that as-fabricated sensors exhibit relatively reproducible and good response to ethanol gas. Typically, the response to 100 ppm ethanol in air is around 11.8, and response and recovery times are around 4 and 30 s, respectively.