Zinc oxide nanoparticles: chemical mechanisms and classical and non-classical crystallization.

Among all the functional materials, ZnO plays an outstanding role in terms of chemical and physical properties, but also in terms of morphological variety and the number of reported synthesis approaches. Complex shapes and hierarchical architectures make ZnO a perfect example to study chemical and crystallization mechanisms. In this review article, we will discuss the nucleation and growth of ZnO nanostructures in liquid media by classical and non-classical (i.e., particle-based) crystallization pathways. We elaborate the chemical conditions and parameters that are responsible for the occurrence of one or the other pathway.