GaOOH Crystallite Growth on Liquid Metal Microdroplets in Water: Influence of the Local Environment

Abstract

Gallium-based liquid metals form alloys with a melting point close to or below room temperature. On the surface of these liquid metals, a thin oxide skin is formed once in contact with oxygen, and this oxide skin can be leveraged to stabilize liquid metal micro- and nanodroplets in a liquid. During sonication and storage of these droplets in aqueous solution, gallium oxide hydroxide (GaOOH) forms on these droplets, and given enough time or treatment with heat, a full shape transition and dealloying are observed. In this article, we show that GaOOH can be grown at room temperature and that the growth is dependent on both the local environment and temperature. GaOOH growth on liquid metal microdroplets located at the air/water interface is considerably faster than in the bulk phase. Interestingly, hydrolysis to GaOOH is hampered and stops at 15 °C in bulk water after 6 h. In contrast, hydrolysis commences even at 15 °C for liquid metal microdroplets located at the air/water interface, and full surface coverage is obtained after around 24 h (compared to 12 h at 25 °C at the air/water interface). The X-ray photoelectron spectroscopy (XPS) measurement suggests that gallium oxide is dissolved and Ga(OH)3 is formed as a precursor that reacts in a downstream reaction toward GaOOH. This improved understanding of the GaOOH formation can be leveraged to control the liquid metal micro- and nanodroplet shape and composition (i.e., for biomedical applications).

Liquid-Metal Molecular Scissors

“…As shown in Figure e,f, the solid contents of the eGaIn after them had reacted with water molecules were found to be GaO­(OH); based on IR and Raman spectroscopic analysis, , most of GaO­(OH) materials were converted into Ga 2 O 3 after annealing at 600 °C for 2.0 h, as depicted in eqs and . This confirms that eGaIn has an excellent ability to cut H–O bonds in H 2 O molecules. − …”

“…As shown in Figure e,f, the solid contents of the eGaIn after them had reacted with water molecules were found to be GaO(OH); based on IR and Raman spectroscopic analysis, , most of GaO(OH) materials were converted into Ga 2 O 3 after annealing at 600 °C for 2.0 h, as depicted in eqs and . This confirms that eGaIn has an excellent ability to cut H–O bonds in H 2 O molecules. − normalG normala false( normall false) + H 2 O false( normall false) = G a O false( normalO normalH false) false( normals false) + H 2 ( g ) 2 G a O false( normalO normalH false) false( normals false) = normalG normala 2 O 3 ( s ) + H 2 O false( normalg false) …”

Room‐Temperature Liquid Metals for Flexible Electronic Devices

“…[ 69 ] Typically, in aqueous solution or under hydrothermal conditions, with time increases, GaOOH can be obtained through Equations () and () by hydrolysis of Ga 2 O 3 . Crystallite growth of such oxyhydroxide superficially altering morphology and dealloying of RTGLMs occurs [ 65,68,70 ] $$$$\begin{equation}{\mathrm{4Ga}}\left( {\mathrm{1}} \right)\;{\mathrm{ + }}\;{\mathrm{Ga}}_{\mathrm{2}}{{\mathrm{O}}}_{\mathrm{3}}\left( {\mathrm{s}} \right) \to {\mathrm{3G}}{{\mathrm{a}}}_{\mathrm{2}}{\mathrm{O}}\left( {\mathrm{s}} \right)\end{equation}$$$$…”

“…[69] Typically, in aqueous solution or under hydrothermal conditions, with time increases, GaOOH can be obtained through Equations (3) and ( 4) by hydrolysis of Ga 2 O 3 . Crystallite growth of such www.small-journal.com oxyhydroxide superficially altering morphology and dealloying of RTGLMs occurs [65,68,70] 4Ga (1) + Ga 2 O 3 (s) → 3Ga 2 O (s) (7) The oxides on the surface of liquid metals can be employed to stabilize micro-or nanosized liquid metal droplets on an even keel during processing and raptured to realize coalescence of droplets and restore their electrical conductivity under optimal mechanical/thermal/acoustical/lasering stimulus and the oxidation can be thermally regulated to achieve fluorescence color and intensity shift (Figure 3c). [71][72][73][74][75] Notably, in some cases we do not crave fast surface oxidation transition of RT-GaLMs that is, low elasticity, low surface tension, high yield stress, and high adhesion, which hindering broader applications in fluidic, energy harvesting devices, and actuators.…”

Coating of gallium-based liquid metal particles with molybdenum oxide and oxysulfide for electronic band structure modulation

“…Specifically, gallium and its alloys in liquid form hold intriguing properties and could be utilised in various applications. [1][2][3][4][5][6] They can serve as unique electron-rich metallic media that offer suitable environments for fast reactions with other metallic entities, not possible for other liquids and also solid entities. At the interface, the naturally reactive and atomically smooth surfaces serve as an ideal area for templating thin films and two-dimensional materials.…”