Silver nanocrystals grown on a poly(dG)-poly(dC) double stranded DNA scaffold displayed circular dichroism at their surface plasmon excitation band. This chiral plasmon signature was not observed in a control experiment where silver nanocrystals of similar size were produced without the DNA template and adsorbed to the DNA. It is concluded that the DNA templated Ag nanocrystals had a preferred structural handedness.
The surfactant-assisted seeded growth method was adapted for growth of gold nanorods directly on mica surfaces. Spherical gold seed particles were first linked to the surface and then dipped in a cationic surfactant growth solution. Part of the grown particles were nanorods with a typical length of several hundred nanometers and diameter of 10-20 nm. The probability to grow elongated particles out of a seed on the surface was found to be larger than the comparable solution growth process. Successive dipping in the growth solution was found to increase the length and thickness of the gold nanorods without a significant increase in aspect ratio.
Thin, long gold/silver nanowires were grown on substrates in thin surfactant solution films. This growth process occurred exclusively in thinning aqueous films as the water evaporated, and elongated surfactant template structures were formed. The nanowire growth depended on the presence of a relatively high concentration of silver ions (typical Ag:Au mole ratio of 1:1). Tuning the pH value to about 5 in the growth solution was crucial for the nanowire growth. Further development of this process may lead to a simple wet chemical technique for the fabrication of relatively uniform arrays of metal nanowires on surfaces.
Ruthenium phosphides are known to
be highly stable and conductive
materials. A new process was developed to prepare ruthenium phosphide
catalysts for oxygen reduction in acid solutions. Several synthesis
methods have been applied to form pure RuP and Ru2P as
well as mixed phases of Ru and Ru
x
P (x ≥ 1). These methods utilize high-temperature solid-state
synthesis and reaction under autogenic pressure at elevated temperature
(RAPET). On the basis of rotating ring–disk electrode (RRDE)
experiments, oxygen reduction activity was observed on all Ru
x
P materials. Characteristic kinetic parameters
show specific exchange current densities in the range of 0.4–1.4
mA mg–1, Tafel slopes of 129–135 mV dec–1, and %H2O2 of 3–11%
of the total current. Complementary XPS and Raman spectral analysis
reveals a highly oxidized surface with significant presence of PO4
3– and RuO2 species. To the best
of our knowledge, this is the first report identifying oxygen reduction
activity on Ru
x
P.
Gold-palladium nanocrystals with starlike shapes and high aspect ratio nanowires were grown in a surfactant solution. The incorporation of palladium into the growing gold nanostructures induced nanowire formation with high yield. Kinetic control of the metal deposition rate through tuning of the pH value to about 5 was crucial for the nanowire growth. The nanostructures were characterized by high-resolution electron microscopy and energy-dispersive X-ray spectroscopy. The Au-Pd nanowires were deposited on functionalized silicon wafers.
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