Ligand-assisted synthesis of functional inorganic nanomaterials with hierarchical nanostructure

Single-nanoscale (<10 nm) inorganic materials exhibit performance superior to that of bulk materials (>100 nm); however, most nanomaterials are yet to gain industrial applications due to their low durability, dispersibility, and difficulties in handling. Inorganic nanomaterials with hierarchical nanostructures, such as flower-, sheaf-, and leaf-like structures, are promising for various applications owing to their high surface activity, structural stability, good dispersibility, and recoverability, attributed to their submicrometer to microscale overall diameter and single-nanoscale open surface structures. In liquid-phase syntheses, additives function as ligands. For example, organic molecules and inorganic ions play an important role in the formation of hierarchical nanoarchitectures. Herein, I review ligand-assisted synthesis techniques based on the non-classical crystallization theory for fabricating nanoarchitectures and the high functionalities for catalytic, electrochemical, and gas sensing applications of the resulting nanostructures. I further discuss in detail the mesocrystal structures, orientation, functionalization, and formation mechanisms with tiny organic molecules and inorganic ions for spiky-shaped Nb2O5 particles and raspberry-shaped Co3O4 nanoparticles.