Design of highly porous SnO2-CuO nanotubes for enhancing H2S gas sensor performance

Abstract

Highly porous SnO2-CuO hollow nanofiber mats were synthesized by electrospinning combined with thermal processing for high performance H2S gas sensing applications. The porous morphology generated in the one-dimensional (1-D) nanocomposite led to an improvement in surface-to-adsorbate molecule interactions. Our novel concept lies in fabrication of SnO2-CuO with a 1-D highly porous structure by electrospinning coupled with generation of hollow nanostructures drawing on nanofiber-to-nanotube transformation affected by Kirkendall effect during thermal processing. The fibrous structure was synthesized by electrospinning with mixed solution of Sn and Cu precursors, which then underwent heat treatment under various temperature conditions. The hollow structures were generated based on the different diffusion rates between SnO2-CuO and Sn/Cu. The SnO2-CuO nanotubes have low operating temperatures and high H2S sensing performance. The increased surface area for detecting H2S resulted in great enhancement of the response (Ra/Rg = 1395) and a very fast response time of 5.27 s with a stable recovery time to a low concentration of H2S to 5 ppm at 200 °C. The porous SnO2-CuO hollow nanofiber gas sensor proved to be a promising candidate for gas sensor systems due to increased surface area with metal oxide catalyst. The mechanisms involved in enhancement of gas response and extended applications are also discussed.