Core–shell bimetallic nanocrystals have enhanced properties – such as electrocatalytic activity for ethanol oxidation – relative to their monometallic counterparts. The properties of Au@Pd core–shell nanocrystals depend on their sizes and morphologies. Many shapes can be prepared, although the different morphologies are rarely obtained in the same reaction system, making it difficult to elucidate the mechanisms responsible for the different morphologies.
Younan Xia, Washington University, USA, and colleagues have shown that the size and morphology of Au@Pd core–shell nanocrystals can be controlled through seed-mediated growth. Starting from 11 nm Au nanospheres as the seeds, they obtained Au@Pd core–shell nanocrystals with a number of morphologies, including octahedra, concave octahedra, rectangular bars, cubes, concave cubes, and dendrites, by simply increasing the reaction rate through altering a set of experimental parameters, including the type and concentration of capping agent, the amount of reductant, and the injection rate for the precursor solution. In addition, the as-prepared Au@Pd nanocubes were then used as seeds to generate Au@Pd@Au and Au@Pd@Au@Pd nanocrystals with a multishelled structure.
The team believes that this strategy based on manipulation of reaction kinetics could become a general, facile, and effective means for rationally controlling the size and morphology of core–shell nanocrystals with a variety of different bimetallic compositions.
Image: © Wiley-VCH
- Controlling the Size and Morphology of Au@Pd Core–Shell Nanocrystals by Manipulating the Kinetics of Seeded Growth,
J. Li, Y. Zheng, J. Zeng, Y. Xia,
Chem. Eur. J. 2012.