Field’s Metal Nanodroplets for Creating Phase-Change Materials

Abstract

Liquid metal nanodroplets are an emerging class of nanostructures with profound potential in catalysis, sensing, and biomedical applications owing to their characteristically high surface area. However, the formation of metal nanodroplets is challenging because of their high surface tension; hence, high power sonification is typically applied, which adversely leads to polydispersed size distributions. Here, we demonstrate the surfactant-driven formation of sub-50-nm liquid metal droplets in a nonpolar solvent–oleic acid mixture, without the use of sonication. Oleic acid was found to be crucial for the droplet formation process and stabilization of the resulting colloid. It is proposed that micelle formation drives liquid metal droplet formation and stabilization. The synthesized metal nanodroplets may hold potential for applications as phase- and shape-change materials. By modifying the composition of the liquid metal nanodroplet’s core with additional functional metals, this generic synthesis method can be extended to generate functional liquid metal nanodroplets with tailored properties.

Liquid Metal Alloy Catalysis – Challenges and Prospects

“…Reprinted from [4] Copyright (2021), with permission from Elsevier. (c) A schematic overview of the one‐pot liquid metal nanodroplet synthesis method, illustrating the breakup of bulk liquid metal in a solution of 10 % oleic acid (OA) in hexadecane (C 16 ) into sub‐50‐nm droplets using a shearing–emulsification method [10] . Reprinted (adopted) with permission from [10] copyright (2022) American Chemical Society.…”

“…[36b] Mechanical agitation, another widely exploited top-down synthesis approach, entails using a magnetic stirrer. [38] However, this method has the drawbacks of long emulsification times and the need of significant shear force to reduce the size of the metal alloy, leading to morphological non-homogeneities and low yields of nanodroplets. [21,38] Figure 2(c) illustrates the nanosized droplets of liquid metal alloys formed through mechanical agitation method under ambient conditions.…”

“…[38] However, this method has the drawbacks of long emulsification times and the need of significant shear force to reduce the size of the metal alloy, leading to morphological non-homogeneities and low yields of nanodroplets. [21,38] Figure 2(c) illustrates the nanosized droplets of liquid metal alloys formed through mechanical agitation method under ambient conditions. Ball milling, as shown in Figure 2(d), involves the use of ceramic balls to provide mechanical impact upon milling or grinding to a solvent containing the liquid metal alloy.…”

Spontaneous Liquefaction of Solid Metal–Liquid Metal Interfaces in Colloidal Binary Alloys

“…In contrast to crystallization processes that occur in covalent or ionic solvents, surprisingly little is known about the solvation and colloidal chemistry within liquid metal environments. [ 3 , 4 , 5 , 6 , 7 , 8 ] This is largely due to the opaque nature of molten metals to most light‐based characterization like UV–vis, Raman, and infrared spectroscopy. [ 1 , 9 , 10 , 11 , 12 , 13 , 14 , 15 ] Techniques based on hard X‐rays including X‐ray reflectometry, X‐ray Absorption Spectroscopy, and X‐ray powder diffraction can provide insights, however, these techniques are limited due to their comparatively long data collection times and high photon energy, meaning they predominantly provide long term averaged structural and oxidation state information averaged across a bulk sample.…”

Surface chemistry altering electronic behaviour of liquid metal-derived tin oxide nanosheets

“…[10][11][12][13] Through this approach, both stratified and unstra-tified MOXs have been successfully fabricated, showcasing enhanced properties applicable to electronics, optics, sensing, and catalysis. 9,[14][15][16][17][18] As representative 2D unstratified semiconducting oxides, tin dioxide (SnO 2 ) nanosheets are of technological interest due to their low cost, wide bandgap, excellent electronic properties, and high chemical stability. Utilising the LM method, ultrathin 2D SnO 2 films with an area of several square millimetres have been exfoliated and deposited directly on solid and flexible substrates under atmospheric conditions.…”