One-pot synthesis of ZnO nanowires and belts through orientation attachment mechanism

Abstract: Zinc oxide (ZnO) is one of the promising materials for optoelectronics and advanced electronics-based device fabrication. Nanostructured features include further flavor to the applications as well due to inherent and unprecedented properties. With this view, a sol–gel route for the synthesis of nanostructured ZnO, such as nanoparticles, nanowires and nanobelts subsequently obtained in one-pot has been reported. The process includes synthesis of monodispersed nanoparticles that can find potential applications as gas sensing layers and transparent conducting layers. Hexagonal wurtzite crystal structure with cell constants, a = 3.2427 Ǻ and c = 5.1948 Ǻ was confirmed by X-ray diffraction. Strong preferential growth along {101} plane indicated the growth of ZnO crystallites along c-axis. Vibrational band for Zn–O stretching and deformation modes was confirmed by Fourier transform infrared absorption spectroscopy. A reasonably well-coverage of ZnO nanoparticles, ca. 1 × 10⁷ nanoparticles/cm² along with size distribution of (13.5 ± 9.0) nm diameter, was obtained by topographic observation of scanning electron microscopy. A series of scanning electron micrographs revealed that as-synthesized nanoparticles were further processed to obtain nanometric wires and belts under controlled conditions. The nanowires were formed from anisotropic agglomeration of nanometric particles, and the belts were formed by agglomeration of these nanometric wires into bundles. A close observation indicated that ZnO nanowires of diameter 40–50 nm were consisted of one to three constituent colloids. Control of these selective agglomeration processes is a key challenge for application of nanowires and belts into useful devices. Graphical Abstract: Evolution of ZnO nanowires and nanobelts via orientation attachment mechanism of ZnO colloids.[Figure not available: see fulltext.]