Nano-Bricks Assembly Toward 1D Metal Oxide Nanorods

The rational design of hybrid nanocrystals structures facilitates electronic and energetic communication between different component, which can optimize their specific performance. In this study, an efficient approach for building intricate ZnO@h-CoO nanocomposites and their derivatives is presented, based on a lattice-match/mismatch mechanism. Due to the ultra-low lattice mismatch between ZnO and hexagonal CoO (as low as 0.18%), the h-CoO layer enables epitaxial growth on the ZnO templates, and ZnO can also grow epitaxially outside the CoO layer with ease. Similarly, the thickness of the epitaxial layer and the number of alternating layers can be adjusted arbitrarily. In contrast to h-CoO, the growth of cubic crystalline oxides (such as MnO) on ZnO results in the formation of nanoparticles due to a large mismatch index (following the Volmer-Weber models). Interestingly, when h-CoO is introduced as a further component into the MnO/ZnO composite, the cubic crystalline particles on the surface of the ZnO do not disturb the epitaxial growth of the h-CoO, allowing for the formation of nanocomposites with more components. Furthermore, additional units can be added to the nanocomposite further based on the lattice-match/mismatch mechanism, which is analogous to the building nano-bricks.