Ultrathin nanostructures: smaller size with new phenomena.

Ultrathin nanostructures possess the very essential features of nanomaterials, including quantum-confinement effects and unconventional reactivities, which are determined by the significant structure variations from the bulk material. More and more isolated reports on ultrathin nanostructures and various new phenomena have appeared in recent years but a comprehensive review on their typical features and future development has not followed. Here we aim to present a well-organized review which comments on the most important characteristics of non-carbon ultrathin nanostructures, in an attemp to reveal the underlying relationship between their reactivity, stability and transformation law, and their structures.