In situ and ex situ studies of platinum nanocrystals: growth and evolution in solution.
In situ studies on the growth and evolution of platinum nanocrystals in solution were carried out using synchrotron-based X-ray diffraction (XRD) techniques. Ex situ low- and high-resolution transmission electron microscopy (TEM) were used to investigate the nanocrystal morphologies through the different growth stages. In a reaction with low precursor concentration, both XRD and TEM results show that growth occurs at a relatively slow rate and yields faceted morphologies, which are characteristic of a thermodynamically controlled regime. In contrast, the platinum nanocrystals in the high-concentration reaction form branched structures and grow at much greater rates under a kinetically controlled regime. Additionally the growth mechanism of the high-concentration reaction involves a morphology transformation from octapod-like shapes to porous nanostructures, which is brought about by a novel mechanism involving selective growth and etching processes that occur simultaneously and at comparable rates.
Cheong
Soshan
S
School of Chemical and Physical Sciences, Victoria University of Wellington, Wellington 6012, New Zealand.
Watt
John
J
Ingham
Bridget
B
Toney
Michael F
MF
Tilley
Richard D
RD