The formation mechanism of Janus nanostructures in one-pot reactions: The case of Ag-Ag₈GeS₆

Herein we describe a large-scale, non-injection "one-pot" batch method for producing large quantities of novel colloidal Ag-Ag₈GeS₆ heteronanostructures. Using a suite of analytical techniques, including high resolution TEM, HAADF-STEM, XEDS mapping, and XRD, the formation mechanism of the nanostructures is elucidated. The formation is discovered to occur in three stages comprising nucleation, phase separation of the metal and semiconductor components, and the final segregation of the metal and semiconductor components to form the Janus nanostructure. The high ionic mobility and chemical reactivity of Ag enables the self-regulated formation of Janus nanostructures in optimized one-pot reactions-a phenomenon that is almost unique to silver-based systems. As such, silver-based systems are ideal candidates to study the formation of Janus nanostructures.