Growth of long ZnO nanowires with high density on ZnO surface for gas sensors

Among the various approaches to grow semiconducting oxide nanowires, the thermal oxidation procedure is considered a simple, efficient and fast method that allows the synthesis of micro and nanostructured arrangements with controlled size and morphology. In the work reported in this paper, long ZnO nanowires were synthesized on the surface of oxidized high-purity Zn foils by heating in air at different rates and temperatures. Size and morphology investigated by scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) for sample heated at 620 oC with heating rate of 20 oC/min reveal the growth of long ZnO nanowires with length of ∽50 μm and average diameter of 74 nm grown along the direction with high population density. Results with different heating rates indicates that this parameter is determinant in tuning the size, morphology and population density of nanowires. X-ray diffraction (XRD) shows patterns for both ZnO and metallic Zn with preferential orienta...