In Situ TEM Study of the Size-Dependent Solubility of Metals in Liquid Metal Nanodroplets

Abstract Characterizing metal solubilities in post-transition-based liquid metals remains challenging due to their inherent opacity to conventional light-based analytical techniques. In this work, we present an in situ heating methodology within a transmission electron microscope that enables direct probing of the behavior of solid metal solutes within the local boundaries of liquid metal nanodroplets. Specifically, we show that the solubility of transition and precious metals in liquid state metallic solvents is dependent on the droplet size that contains them due to the internal Laplace pressure. We also show that the dissolution behaviors of solute metals in gallium–indium and gallium–indium–tin eutectic nanodroplets deviate from that of pure gallium, with solvent composition influencing solubility. Moreover, entropy-driven solubility effects are studied in multicomponent alloys that contain several solutes. The outcomes of this work are crucial for advancing liquid metal-based functionalities of soft systems, particularly for catalysis.