Low-Temperature H₂S Sensors Based on Si-Coated SnO₂ Nanowires

Abstract

To attain high life standards, it is important to develop high-performance non-toxic gas sensors for public safety, environmental pollutant control, industrial processes, etc. Because reports on single element semiconductor-coated semiconducting metal oxides for sensing applications are rare, we synthesized SnO₂ nanowires and coated them with a 5 nm-thick or 10 nm-thick Si layer for H₂S gas sensing studies. SnO₂ nanowires were successfully synthesized using a highly pure metallic Sn powder at high temperature in a tube furnace by the vapor-liquid-solid method and Si was deposited on the nanowires by the sputtering technique. The desired morphology and composition of the synthesized nanowires were confirmed by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and energy-dispersive X-ray spectroscopy. Moreover, the gas sensing characteristics of pristine and Si-coated SnO₂ nanowires toward H₂S, CO, H₂, C₆H₆, C₂H₅ OH and C₆H₇ gases were investigated. The sensing results revealed a good response to H₂S at the optimum operational temperature of 100 degrees C. Notably, Si-coated SnO₂ nanowire sensors showed a better response to H₂S than pristine SnO₂ nanowires. The mechanism of H₂S sensing is discussed in detail here. This study shows that the Si coating on the SnO₂ nanowire enhances its sensing performance and decreases the sensing temperature required for H₂S gas detection.