Facile hydrothermal synthesis of large scale ZnO nanorod arrays and their growth mechanism

Large scale ZnO nanorod arrays (ZNAs) were grown on the indium-doped tin oxide (ITO) glass substrate by a novel and facile hydrothermal method at low temperature. The obtained nanorods were characterized by SEM, XRD, TEM and PL. It is shown that the average diameter of ZnO nanorods (~500 nm) grown on the bare substrate is much bigger than that of nanorods grown on the ZnO-seed-coated substrate (~100 nm). ZNAs grown on ZnO-seed-coated substrate are highly aligned. All the as-grown ZnO nanorods have a very good crystallinity with hexagonal wurtzite structure and grow along the c-axis. Zinc metal spiral plays important roles for the growth of ZnO nanorods, which conduces to generate the additional growth unit of [Zn(OH)⁴]^2-.