Synthesis And Properties Of Noble Metal Nanomaterials

In nano-science and nano-technology, colloidal metal nanoparticles are emerging as key materials for catalysis, plasmonics, and spectroscopy. With the development of synthesis method, it has been pay attention to study the relation between morphology (size, shape, composition) and physical and chemical properties. Nanomaterials with special morphology have been showed good properties and will been application in many field, meanwhile, precise control the morphology to tune special properties have been a hot topic.Seed mediated method was employed to synthesize noble metal nanomaterials with special shape, including monodisperse Au single crystal polyhedra, core-shell polyhedra involving Au, Pd, and Ag. For special shape nanomaterials, SPR and electrochemical properties were studied. The following is the main result:1. Using seed-mediated method to synthesize three types Au polyhedra including rhombic dodecahedra (RD), octahedra (Oct), and cubes, which were bounded with three low-index {110}, {111} and {100} facets, respectively. And then systematically explore the shape-dependent catalytic activities of gold nanoparticles toward glucose oxidation in alkaline electrolytes. Our findings clearly reveal that glucose oxidation is strongly dependent on the crystal facets of Au nanocrystals. The {100}-bounded cubic Au nanocrystals are significantly more active than the {110}-bounded rhombic dodecahedral and {111}-bounded octahedral Au nanocrystals. Furthermore, these Au nanocrystal catalysts exhibit remarkably high stability in the repetitive electrocatalytic oxidation process.2. Au-Pd nano-polyhedral were synthesized through epitaxial growth method in aqueous solution. Ellipsoial Au were employed as the seeds, through reducing H2PdCl4 with L-ascorbic acid in cetyltrimethylammonium bromide (CTAB )solution,simply adjust―growth solution‖environment, Au-Pd core-shell rhombic dodecahedra (RD), octahedra (Oct), and cubes can synthesize. Pd-Au bimetallic nano-polyhedra were also synthesized using cubic Pd as seed, through reducing HAuCl4 with L-ascorbic acid in cetylpyridinium chloride (CPC) solution. The binary metal Au-Pd nanopolyhedra with uniform size were impolyed to study SPR and electrocatalytic. For electrocatalytic properties, the {100}-bounded cubic Au -Pd nanocrystals are significantly more active than the {110}-bounded RD and {111}-bounded octahedral Au-Pd nanocrystals. The study demonstrated for the Au-Pd core-shell nanocrystals, When Pd shells are smaller than 5nm, the SPR of Au-Pd core-shell was observed at 500-508nm. When shells are larger than 5nm, the SPR of Au-Pd are mainly determined by the exterior shell (Pd).3. Au-Pd-Ag and Pd-Au-Ag nano-cubes were synthesized through epitaxial growth method in aqueous solution. Polyhedra Au-Pd and Pd-Au were employed as the seeds, Br- as special absorption ion, through reducing AgNO3 with L-ascorbic acid in cetyltrimethylammonium chloride ( CTAC ) solution. SPR of Au-Pd-Ag and Pd-Au-Ag with different thickness were also study. The SPR of Au-Pd-Ag and Pd-Au-Ag are mainly determined by the exterior shell (Ag) and with decreasing the size of trimetallic core-shell structure, the SPR are blue shift.