Shape-Controlled Metal Nanoparticles and Their Assemblies with Optical Functionalities

Metal nanoparticles (NPs) possess excellent optical, optoelectronic, and optochemical properties based on their surface plasmon resonance. However, for practical use, the morphology and assembly of metal NPs need to be controlled. Here, we review facile control methods including seed-mediated growth accompanied with a comproportionation reaction of seeds to control their morphology and assembly. Several synthetic conditions have been modified to precisely control the morphology of metal NPs. Functionalized mesoporous oxides have also been used as hard templates to align metal nanorods and control their dimensions. The high performance of such metal nanorods in surface-enhanced Raman scattering, polarization of light, and photocatalysis has been measured, and the reasons for their high performance are discussed.