Oxidation of Gallium-based Liquid Metal Alloys by Water

Abstract

Gallium alloys with other low melting point metals, such as indium or tin, to form room-temperature liquid eutectic systems. The gallium in the alloys rapidly forms a thin surface oxide when exposed to ambient oxygen. This surface oxide has been previously exploited for self-stabilization of liquid metal nanoparticles, retention of metastable shapes, and imparting stimuli-responsive behavior to the alloy surface. In this work, we study the effect of water as an oxidant and its role in defining the alloy surface chemistry. We identify several pathways that can lead to the formation of gallium oxide hydroxide (GaOOH) crystallites, which may be undesirable in many applications. Furthermore, we find that some crystallite formation pathways can be reinforced by typical top-down particle synthesis techniques like sonication. This improved understanding of interfacial interactions provides critical insight for process design and implementation of advanced devices that utilize the unique coupling of flexibility and conductivity offered by these gallium-based liquid metal alloys.

Electrochemical behavior and electrodeposition of gallium in 1,2-dimethoxyethane-based electrolytes

“…However, studies investigating gallium and gallium-indium eutectics for liquid metal applications indicate that observed gallium spheres are typically covered by a gallium oxide shell. [34][35][36][37][38] These shells form upon exposure of gallium to even trace amounts of oxygen, and prevent the individual gallium particles from agglomerating to larger-sized entities. 39,40 As our recorded EDX spectrum does not show any peak for oxygen, these oxide shells are presumed to be very thin.…”

Nano‐Biomedicine based on Liquid Metal Particles and Allied Materials

“…[ 63 ] GaOOH is demonstrated to be related with the generation of reactive oxygen species (ROS) in radiosensitization. [ 76,77 ] LMNPs can enable different shapes and composition, including sphere shape, rice shape, and rod shape (Figure 2d,e). [ 50,78 ] Several positive‐charged surfactants, such as cetrimonium bromide or lysozyme, are demonstrated to enable the shape morphing process upon heating, and the indium nanoparticles can be dealloyed as the by‐product.…”

Acoustically‐Propelled Rodlike Liquid Metal Colloidal Motors

“…Furthermore, the X‐ray powder diffraction (XRD) analysis (Figure 1f) shows the existence of gallium oxyhydroxide (GaOOH) and Ga metal in EGaIn colloidal motors. It is supposed that GaOOH is a preferred form of gallium oxide in heating water with a lamellar structure [30–31] . When the EGaIn particles undergo an oxidation reaction in an ultrasonically crushing environment, gallium oxide would transfer into gallium oxide hydroxide, the resulting GaOOH grow along a one‐dimensional direction, making the EGaIn particles radially elongated [32] …”