Noble metal nanoparticle superstructures via liquid/liquid interfacial mass transfer-assisted self-assembly.

Ellipsoidal and spherical superstructures, network structure and hierarchical structure of noble metal spherical or rod-like nanoparticles were fabricated through a liquid/liquid interface mass transfer-assisted self-assembly process in aqueous solutions. • A general approach has been developed to fabricate superstructures of nanoparticles. • A liquid/liquid interface mass transfer process was used to introduce amines into hydrosols. • The fatty amines combined with colloidal particles and organized into superstructures. • Ellipsoidal and spherical superlattices of spherical nanoparticles were obtained. • Network and hierarchical structures of nanospheres and nanorods were obtained. Organized assemblies of noble metal nanoparticles (NPs) exhibit unique optical, electronic and catalytic properties and potential applications in various areas. Many kinds of methods have been developed to fabricate such functional systems. In this work, we report a facile and novel method to fabricate the organized aggregates of Au and Ag NPs. Their freshly prepared hydrosols were used as upper phase, and the DMF/chloroform solutions of different fatty amines were used as bottom phases to form a planar liquid/liquid interface. The mass transfer across the interface occurred immediately, where the DMF droplets containing fatty amines entered into the hydrosols, leading to the formation of organized aggregates of NPs through a self-assembly process of amine molecules. It was found that several kinds of assemblies were generated, including ellipsoidal and spherical superstructures of spherical NPs, networks of spherical NPs and nanorods, and hierarchical structure of nanorods. In addition, networks composed of Au NPs/Ag skeleton satellite-core type nanorods were further constructed, which exhibited good catalytic performance and SERS property. [ABSTRACT FROM AUTHOR]