TEM images. (a) Au25, (b) Au25Pd with the inset showing the Pd nanocrystallites from the Pd shell, (c) Au50, (d) Au50Pd, (e) Au100, and (f) Au100Pd. The obvious dark/white contrast identified in the images of the Au nanospheres indicates that they are porous.
Hsu et al. Nanoscale Research Letters 2013 8:113 doi:10.1186/1556-276X-8-113