Shape Control in Gold Nanoparticle Synthesis*

This chapter summarises some of the emerging protocols for shape control of gold nanocrystals, and examines some of the mechanisms currently proposed to help explain this important advance in materials science. C. Lofton and W. Sigmund provided the first such review in 2005, focusing on the crystallographic aspects of shape control, including twinning. The focus is on how different chemical environments appear to promote the growth of different shapes, from platonic solids through to rods and branched metal nanocrystals. The growth of gold nanorods is, within the field of anisotropic nanoparticle synthesis, the most established protocol, in terms of the degree of control of the size, shape and monodispersity. Of the reported procedures for gold rod formation, seed-mediated growth has been by far the most efficient and popular approach. Other types of anisotropic nanoparticles include triangular or hexagonal plates.