Fabrication of SnO_2 nanotube microyarn and its gas sensing behavior

摘要

Continuously aligned and assembled forms of nanomaterials (e.g., carbon nanotube yarns) have been recognized as an effective means of realizing the marvelous properties of individual nanomaterial in the macro/microscale. Many efforts have been made to develop metal oxide nanotubes, however, few researches have been dedicated to fabricating their microyarns. In this study, we report a fabrication method for SnO_2 nanotube microyarns and their potential applications. The aligned polyacrylonitrile nanofibers were first prepared using electrospinning and they were twisted into a microyarn. SnO_2 was then coated onto the nanofibers in the yarn by atomic layer deposition (ALD). Finally the microyarn consisting of the coated nanofibers was calcined, resulting in a SnO_2 nanotube microyarn. The average diameter of the obtained SnO_2 nanotubes in the microyarn was around 500nm, and their wall thickness was approximately 70nm when 1000 cycles of the ALD process were applied. The lattice fringes in the high resolution transmission electron microscope image and selected area electron diffraction pattern revealed that the nanotubes were polycrystalline SnO_2 with a rutile structure. The SnO_2 nanotube microyarn fabricated in this study has the potential to be applied for the development of a multiple-celled gas sensor, which has been confirmed by carrying out H_2 gas sensing at 400 °C using a one-celled sensor. The results showed the stable and reversible gas sensing of the nanotube yarn, demonstrating that the nanotube yarns can be incorporated into a multiple-celled sensor due to their handling convenience, stable structure, and gas sensing performance.