2 research outputs found
Improved Size-Tunable Synthesis of Monodisperse Gold Nanorods through the Use of Aromatic Additives
We report an improved synthesis of colloidal gold nanorods (NRs) by using aromatic additives that reduce the concentration of hexadecyltrimethylammonium bromide surfactant to ∼0.05 M as opposed to 0.1 M in well-established protocols. The method optimizes the synthesis for each of the 11 additives studied, allowing a rich array of monodisperse gold NRs with longitudinal surface plasmon resonance tunable from 627 to 1246 nm to be generated. The gold NRs form large-area ordered assemblies upon slow evaporation of NR solution, exhibiting liquid crystalline ordering and several distinct local packing motifs that are dependent upon the NR’s aspect ratio. Tailored synthesis of gold NRs with simultaneous improvements in monodispersity and dimensional tunability through rational introduction of additives will not only help to better understand the mechanism of seed-mediated growth of gold NRs but also advance the research on plasmonic metamaterials incorporating anisotropic metal nanostructures
Engineering Catalytic Contacts and Thermal Stability: Gold/Iron Oxide Binary Nanocrystal Superlattices for CO Oxidation
Well-defined surface, such as surface of a single crystal,
is being
used to provide precise interpretation of catalytic processes, while
the nanoparticulate model catalyst more closely represents the real
catalysts that are used in industrial processes. Nanocrystal superlattice,
which combines the chemical and physical properties of different materials
in a single crystalline structure, is an ideal model catalyst, that
bridge between conventional models and real catalysts. We identify
the active sites for carbon monoxide (CO) oxidation on Au-FeO<sub><i>x</i></sub> catalysts by using Au-FeO<sub><i>x</i></sub> binary superlattices correlating the activity to the number
density of catalytic contacts between Au and FeO<sub><i>x</i></sub>. Moreover, using nanocrystal superlattices, we propose a general
strategy of keeping active metals spatially confined to enhance the
stability of metal catalysts. With a great range of nanocrystal superlattice
structures and compositions, we establish that nanocrystal superlattices
are useful model materials through which to explore, understand, and
improve catalytic processes bridging the gap between traditional single
crystal and supported catalyst studies