Shape Transformation Mechanism of Gallium–Indium Alloyed Liquid Metal Nanoparticles

Eutectic gallium indium (EGaIn) spherical liquid metal nanoparticles (NPs) can transform to gallium oxide hydroxide (GaOOH) microrods in water. Nevertheless, the mechanism of this process still remains unrevealed. In this work, the whole shape transformation process of EGaIn NPs is investigated via monitoring the change of NPs’ composition and morphology. Gallium (Ga) element in EGaIn NPs can be oxidized to form gallium oxide, which further reacts with water to generate micrometer-sized GaOOH crystals. This chemical variation occurs gently at room temperature and is accelerated by heating. With continuous consumption of Ga element, indium condenses to form individual NPs. The dynamic temperature-dependent dissolution and precipitation of GaOOH microrods in water are further demonstrated. Deep understanding of the mechanism of EGaIn NPs’ shape transformation would provide more approaches to control the surface and bulk properties of NPs for potential applications in various fields including soft robotics, wearable devices, and nanomedicine.