Green, Water-Based Synthesis of ZnO Nanostructures

We report on the synthesis of zinc oxide (ZnO) nanostructures using a simple, green, waterbased process, without the aid of any chemical precursor or external energy source. Zinc plates were immersed in deionized water and kept at ambient conditions in a dark cabinet for up to 21 days. After immersion, the reaction products were analyzed using scanning electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, photoluminescence spectroscopy and Raman spectroscopy. After short immersion times (1-3 days), ZnO agglomerates with a high concentration of oxygen defects were formed, which overlapped along the c axis to form ZnO nanoflowers. After long immersion times (21 days), ZnO microswords with smooth surfaces, well-defined tips, and less oxygen defects were formed. This low-cost, low-energy synthesis process is an attractive alternative to produce ZnO nanostructures with low impact on the environment.