Influence of ammonia sources on the gas sensing properties of the direct grown ZnO nanomaterials

ZnO nanomaterials have been directly grown on Al2O3 ceramic tube by two step seeds-assisted solution method with different ammonia sources. The crystalline phase and morphology of the ZnO nanomaterials are characterized by XRD and SEM. The results of SEM reveal that the ZnO nanomaterials present different morphologies and hierarchical structures where rhombus-shaped nanoprisms, nanorods assembled nanoflowers and nanoleaves constructed nanourchins are obtained in NH4F, hexamethylenetetramine (HMT) and urea, respectively. All of the ZnO nanomaterials show the optimal working temperature at 320 A degrees C and excellent repeatability. Gas sensing experiments demonstrate that the ZnO nanomateirals perform high responses and fast response-recovery to volatile organic compounds, especially for the nanorods assembled nanoflowers prepared in the HMT. It is believed that the enhancement of the gas sensing performances is mainly attributed to the hierarchical structures, exposed deficiencies and excellent ohm contact of the direct grown ZnO nanomaterials.