Hydrogen Gas Sensors Using ZnO-SnO(2) Core-Shell Nanostructure

Abstract

The fabrication and electrical properties of H(2) gas sensor with ZnO-SnO(2) core shell nanostructure were studied. The ZnO-SnO(2) core shell nanowires were synthesized through a novel two-step chemical growth. The structure, morphology and composition of the nanowires were investigated by transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray spectrometer (EDS) and X-ray photoelectron spectrometer (XPS), respectively. The experimental results showed that the amorphous SnO(2) was uniformly coated onto the entire ZnO single crystal nanowire to form ZnO-SnO(2) core shell nanostructure. The electrical properties of the core shell nanowires in 25-200 ppm of hydrogen (H2) were measured at temperature of 250 C. It was found that the ZnO-SnO(2) core shell nanowires exhibited excellent hydrogen sensor performance, such as the sensitivity is up to 89% against 200 ppm hydrogen. Such high sensitivity was believed to be controlled by the nanoscale SnO(2) layer, which was determined from pinch-off and fully conductive state. The ZnO SnO(2) core shell nanostructures made by two-step chemical growth have high potential for gas sensor application.