pH-controlled surface engineering of nanostructured ZnO films generated via a sustainable low-temperature H2O oxidation process

Abstract Developing a consistent and sustainable protocol for fabricating predetermined ZnO nanostructures is of significant interest in materials science and industry, owing to the emergence of ZnO-based devices and applications. Herein, the design of novel nanostructured ZnO films via a green, sustainable and low-temperature H 2 O oxidation technique is presented. Surface engineering was achieved by controlling the pH value of H 2 O during oxidation of Zn thin films. Diverse ZnO nanostructures of high structural and optical qualities including nanoparticles, microparticles composed of smaller rods, columnar nanorods and nanotubes having different growth orientations emerged. The morphology, chemical composition, structure, surface chemistry and optical properties of the nanomaterials were comprehensively characterized as a function of pH value. The experimental results and proposed growth mechanism for each nanostructure were presented and thoroughly discussed to have a deeper understanding on the physical insights governing the pH-controlled development of the nanostructures. This in-depth examination could pave the way to pioneering properties and functionalities that could sustainably fulfill the requirements of next generation optoelectronic devices.