Controllable Synthesis of Well-aligned ZnO Nanorod Arrays on Varying Substrates via Rapid Electrodeposition

A facile and rapid electrodeposition route was developed to controllably synthesize well-aligned ZnO nanorod arrays on diverse substrates, such as seed-layer pre-formed, pristine indium tin oxide (ITO) and Si, using Zn(NO3)2·6H2O and hexamethylenetetramine (HMT) as the precursors. X-ray diffraction (XRD) and transmission electron microscopy (TEM) results indicated that seed-layer pre-modified of ZnO nanorod arrays (ZNRs) possessed single crystalline, a wurtzite crystal structure with preferential growth orientation along [0001] direction. The ZNRs on pre-modified ZnO seed-layer (ZSL) had diameters of 30-50 nm, and aligned vertically to the substrates. ZNRs on ZSL/ITO substrate exhibited a high transmittance (above 80%) in visible wavelength range and the red-shift of band gap energy. An electrochemical reaction model was proposed to explain the growth process of ZnO nanorods. Importantly, the rapid synthesis of ZNRs provided the feasibility of preparation of SERS (surface enhanced Raman scattering) nanocomposite within shorter time by a subsequent electrochemical etching.