Unzipping Chemical Bonds of Non-Layered Bulk Structures to Form Ultrathin Nanocrystals

The rich electronic and band structures of monolayered crystals offer versatile physical/chemical properties and subsequently a wide range of applications. Fabrication, particularly by the top-down “exfoliation” processes, rely on the presence of weak Van der Waals force between individual layers. Due to the strong chemical bonds between planes and atoms, un-zipping ultra-thin crystals (from one to several unit cells thick) from non-layered structures is more challenging. This work reports a technique which can be used to prepare such ultra-thin crystals from bulk non-layered structures (ɑ-/β-MnO2, ZnO, TiO2, ɑ-TiB2). The physical and optical properties of these materials are characterized and contrasted against those from their bulk phases. The work presented here represents a tool kit for the preparation of novel 2D non-layered nanomaterials, providing significant contributions to this family of materials, paving the way for even more applications. Furthermore, we show the application of these novel NCs for bio-sensing and electrochemical oxygen reduction.