A synthesis and sensing application of hollow ZnO nanofibers with uniform wall thicknesses grown using polymer templates

A novel approach is applied to fabricating hollow ZnO nanofibers (ZNFs) with uniform wall thicknesses. In this approach, polymers synthesized by electrospinning are used as sacrificial templates and ZnO is subsequently deposited on these templates using atomic layer deposition, which makes ZnO uniformly cover the round surface of the polymer nanofibers. Heat treatments result in the selective removal of the polymer templates and the formation of hollow ZNFs with very uniform wall thicknesses. To test a potential use of hollow ZNFs in chemical gas sensors, their sensing properties with regard to O-2, NO2, and CO are investigated in a comparative manner with those of normal ZnO nanofibers. The excellent sensing properties observed in the hollow ZNF sensor are ascribed to (1) the more pronounced change in resistance due to the presence of nanograins and (2) the doubling of the surface-to-volume ratio due to the generation of inner surfaces.