A Colloidal Nanofoundry for Catalytically Active Solid-Liquid-Solid Nanoparticles

Abstract Nanoreactors represent a unique strategy to synthesize nanoclusters and nanoparticles with a diverse chemical nature and with a level of tunability that is difficult to achieve with conventional methods. Liquid metals (LMs) have emerged as an intriguing medium for materials synthesis, which hints at opportunities to their use as nanoreactors. Yet, their underdeveloped chemistry at the nanoscale has so far hindered the full exploitation of this research direction. Herein, we advance the chemical knowledge on the synthesis of LM nanoparticles (NPs) and demonstrate their use as a novel type of nanoreactor to access well-defined multi-metallic NPs. We propose a novel approach for the synthesis of colloidal solid-liquid-solid core-shell-shell NPs wherein a solid metal core (i.e. Ag, Au, Cu, Pd) is embedded into a liquid Ga NP surrounded by its native oxide skin. Using state of the art characterization tools, including in-situ electron microscopy and X-Ray absorption spectroscopy, we learn that a dissolution and recrystallization of the solid core within the liquid Ga NP occurs during the synthesis. We leverage this understanding to access unprecedented multi-metallic NPs, exemplified by Ag-Au nanodimers, within the liquid Ga shell. Finally, we demonstrate how the synergistic interactions between the solid metal core, the liquid Ga domain and the oxide skin are promising to explore these materials as a new class of electrocatalysts. The findings of this work deepen our understanding of LM NPs and advance the ability to design these unique nanomaterials with tailored properties for various applications using a novel nanoreactor strategy.