Illustrating the formation of metal nanoparticles with a growth concept based on colloidal stability.

A large number of scientific contributions is dedicated to syntheses, characterization and applications of metal nanoparticles. In contrast, only few studies on their formation mechanisms have been reported. In general, concepts to describe particle growth processes are rare. Commonly used models are not able to explain the influences of reaction parameters on the growth and the final particle size. In this contribution it is shown how the growth of colloidal metal nanoparticles can be illustrated using an approach based on colloidal stability. In the first part, investigations of various syntheses of colloidal nanoparticles (including Rh, Pd, Pt, Cu, Ag and Au) show that growth due to aggregation and coalescence is the governing principle of nanoparticle formation if the monomer supply is faster than the actual growth. In the second part of this contribution, the influences of various parameters on the growth of Au nanoparticles are studied and it is demonstrated how the colloidal stability approach can illustrate the impact of synthesis parameters on the final particle size.