Octahedral noble-metal nanoparticles and their electrocatalytic properties.

Octahedrally shaped noble-metal nanocrystals are fascinating for their unique properties, such as electrocatalytic, catalytic, plasmonic, and optical behavior, owing to their exclusively exposed {111} facets; Oh symmetric structure; and close-packed surface atoms in low-index surface categories, which are normally stable in a reaction. A series of protocols in the preparation of noble-metal nano-octahedra through a wet-chemical synthetic strategy have been developed in recent years. Herein, advances in synthetic approaches and mechanistic studies of noble-metal nano-octahedra are systematically discussed and key factors, including reduction kinetics, selective capping, and epitaxial growth, are outlined. Their unique performance as advanced electrocatalysts towards fuel-cell reactions is highlighted as well.