Synthesis of hybrid Au-Ag₂S-Cu_2-xS nanocrystals with disparate interfacial features

Hybrid nanocrystals (NCs) with multiple components and junctions have attracted considerable attention due to their promising synergistic properties. In particular, great attention has been paid to the manipulation of buried multijunction heterointerfaces because they are closely related to the surface energy and carrier transfer of NCs. However, heterointerfaced NCs are usually constructed by sequential step-by-step pathways, and buried interfaces can only be formed along a given direction, resulting in the one and only spatial orientation of multiple interfaces. In this work, we demonstrate two types of Au-Ag₂S-Cu_2-xS NCs with disparate interfacial features. Specifically, the first type (Type I) is prepared through a routine two-step method and shows that Au domain close to the Ag₂S-Cu_2-xS interface; another type (Type II) is achieved by a facile one-pot synthesis procedure and contains Au domain with an interphase only with the Ag₂S domain, far from the Cu_2-xS domain. More importantly, type II NCs could not be formed through other traditional strategies and an underlying mechanism of formation is developed by monitoring the evolution process. Au@Ag core-shell NCs, metastable Au@Ag₂S NCs and Janus Au-Ag₂S NCs are formed successively before the Cu_2-xS domain appears. We speculate that the Au@Ag₂S intermediate plays an essential role in building the final complex nanostructure. We expect that such a simple and facile one-pot method will be used to fabricate additional asymmetric multicomponent NCs with distinctive interfacial features and promising potential applications.