A colloidal approach for the synthesis of catalytically active solid–liquid–solid nanoparticles

Nanoreactors can synthesize highly tunable nanomaterials beyond the reach of conventional methods. Liquid metals (LMs) have emerged as an interesting reaction medium for materials synthesis. However, the limited understanding of their chemistry at the nanoscale has so far hindered the broader exploration of LMs in the synthesis of nanomaterials. Here we advance the chemistry of LM nanoparticles (NPs) and demonstrate the use of these NPs as nanoreactors to access well-defined, compositionally tunable multimetallic NPs. We propose a colloidal approach to synthesize solid–liquid–solid core–shell–shell NPs in which a solid metal core (silver, gold, copper or palladium) is embedded into a liquid gallium NP surrounded by its native oxide skin. Using state-of-the-art characterization, we observe the dissolution and recrystallization of the solid metal core within the liquid gallium NP during the synthesis. We leverage this understanding to access unprecedented multimetallic NPs, exemplified by Ag–Au nanodimers within a liquid gallium shell. Finally, we show that solid–liquid–solid NPs are promising electrocatalysts with improved structural stability over the solid core only. (Figure presented.)