One-pot controllable synthesis of the missing uniform icosidodecahedral gold nanocrystals with high-index facets and their plasmonic properties

Abstract

Noble metal (e.g., Au, Pt, Pd) nanocrystals (NCs) enclosed by high-index facets have been the subject of intensive research in recent years, owing to their unconventional constructions with aesthetic beauty, peculiar synthetic approaches, significantly enhanced physicochemical properties, and potential wide variety of practical applications. However, because of their general exposed high surface energy, the challenge of chemically preparing noble metal NCs having high-index facets remains elusive. In the present paper, we develop a new, facile and effective method for the controllable synthesis of the missing high-quality icosidodecahedral Au NCs in a one-pot polyol reaction. The as-prepared icosidodecahedral Au NCs with unique hyperpolyhedral shapes and smooth surfaces were enclosed by 8 low-index {111} facets and 24 high-index {310} facets. Our proposed synthetic strategy is highlighted by its simplicity (requires no foreign metal ions, no seeds or no conductive substrates), high-yield production and particular controllability of the synthesis. Formation of the specific icosidodecahedral Au NCs was attributed to the synergistic reduction of gold ethylene glycol (EG) precursors in a refluxing 1,5-pentanediol (PD) solution assisted by the cationic surfactant poly(diallyldimethylammonium) chloride (PDDA) as well as the probable positive oxidative etching process. The morphology evolution caused by different experimental parameters and the corresponding plasmonic optical properties of icosidodecahedral Au NCs were investigated in some detail. It is expected that these uniform icosidodecahedral Au NCs with excellent stability and interesting plasmonic absorption properties would have potential applications in surface plasmonics, fuel cells, catalysis, optoelectronics, metamaterials, surface-enhanced Raman scattering (SERS) and biomedicine.