Hydrogen Gas Sensors Using ZnO-SnO2 Core-Shell Nanostructure

The fabrication and electrical properties of H-2 gas sensor with ZnO-SnO2 core shell nanostructure were studied. The ZnO-SnO2 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 SnO2 was uniformly coated onto the entire ZnO single crystal nanowire to form ZnO-SnO2 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-SnO2 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 SnO2 layer, which was determined from pinch-off and fully conductive state. The ZnO SnO2 core shell nanostructures made by two-step chemical growth have high potential for gas sensor application.