Aqueous Mechanical Oxidation of Zn Dust: An Inventive Technique for Bulk Production of ZnO Nanorods

Metal to bulk metal oxide nanoparticles have been successfully processed via a sustainable, facile, and ecofriendly (green) approach, namely, aqueous mechanical-oxidation. Micron-sized zinc (Zn) dust (∼45 μm) was directly wet-milled using ceramic milling media for 72 h, resulting in the production of bulk monocrystalline ZnO nanorods (aspect ratio ∼5.2, hydrodynamic diameter of 315 nm) and voluminous H₂ gas by catalyst-free water-splitting reaction. The mill-induced surface oxidation and the chemical purity of the synthesized nano ZnO were carefully studied using the XPS analysis. Other standard analytical tools were also employed to understand the crystallinity, phase purity, morphology, and surface area of the final artifact. The photocatalytic activities of these mechanically grown ZnO nanorods were ascertained from two cationic dye-degradation experiments, using the dyes methylene blue and rhodamine 6G. In a nutshell, the study throws a new insight into a cost-effective, zero-effluent, single-step, and parallel-processing approach of two high-value products, bulk nano ZnO and catalyst-free H₂ gas from micronic Zn dust.