Revealing Facet Development During Nanocube Growth
The facet development of a Pt nanocube viewed along the  axis. Sequential TEM images show the growth of the Pt nanocube compared with simulated TEM images. The measured average crystal center-to-facet distance as a function of time revealing a selective facet’s arrested growth mechanism.
Real time imaging of platinum nanocube growth using liquid cell transmission electron microscopy (TEM) led to breakthroughs in the understanding of nanocrystal shape control mechanisms.
Significance and Impact
The ability to directly observe atomic scale details of facet evolution during nanoparticle growth enabled the discovery that surface energy minimization law breaks down at nanoscale. The mobility of surfactant ligands on different facets defines the shape of a nanocrystal. These findings impact the design of novel materials.
Haimei Zheng’s team at Berkeley Lab made new breakthroughs in their research on liquid cell transmission electron microscopy (TEM). Using the advanced liquid cell development and new direct electron detection technology, they captured the atomic facet development during platinum nanocube formation with high spatial and high temporal resolution. Direct observation reveals that the widely accepted crystal shape control theorem of surface energy minimization law breaks down at the nanoscale. They found all facets grow at a similar rate and the mobility surfactant ligands on different facets defines the shape. These findings allow the future design of novel materials with desired properties.