TEM study of fivefold twined gold nanocrystal formation mechanism

• We imaged nanocrystals in eutectic based ionic liquid.
• We studied the growth of nanocrystal by in situ TEM.
• Observation indicates possible growth mechanisms for five-fold twinned nanoparticles.

Nanocrystals play a key role in modern science and technology, and there has been much effort in recent years in tailoring the size, shape, and properties of nanocrystals. The capability to monitor the colloidal nanocrystal growth in liquid is essential for fully understanding the growth and shape control mechanisms. In current study, we imaged nanocrystals in a eutectic-based ionic liquid and studied the growth of five-fold twined gold nanocrystal with in situ transmission electron microscopy (TEM). Our studies suggest that the coalescence-based growth may be also an important mechanism for the formation of twinned nanocrystals in solution in addition to nucleation-based layer-by-layer growth and successive growth twinning mechanisms. This observation reveals much important information about colloidal nanocrystal growth, and is very beneficial in a detailed understanding of growth mechanisms and precise shape controlling synthesis of nanoparticles.