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Liquid metal nanodroplets are an emerging class of underexplored materials with significant potential in many applications, including catalysis, bio‐therapeutics, and phase‐change materials. These nanostructures are generally synthesized by mechanical agitation via ultrasonication of low‐melting metals like Ga. Once these materials are successfully synthesized, they can be suspended in a vast array of different solvents. However, one major issue arises specifically with liquid metal alloys which are found to de‐alloy in the sonication process. Here, it is demonstrated that this challenge can be overcome by undertaking sonication at high temperatures, suspending nanodroplets within molten sodium acetate (NaOAc). After cooling, the nanostructures become planet‐like nanodroplets which are covered by an interfacial oxide crust, feature a liquid metal mantle, and a solid core. The molten salt solvent can effectively be removed rendering this approach to be ideal, especially for catalysts. The proof‐of‐concept application is demonstrated by carrying out electrocatalytic ethanol oxidation, using the Cu–Ga system. The superior performance of the Cu–Ga nanodroplets highlights potential in catalyzing a vast array of reactions. Aside from the Cu–Ga system, this facile process can be applied to multiple other systems, including Ag–Ga, Zn–Ga, Bi–Ga, In–Cu, and Sn–Cu. [ABSTRACT FROM AUTHOR]

Liquid metals (LMs) are emerging as unique fluids for a variety of applications, but their nanoscale solvation properties remain largely understudied. In this work, a combination of atomic force microscopy (AFM) and molecular dynamics (MD) simulations are used to investigate the structure of the interface between the bulk room temperature liquid metal (RTLM) and the LM oxide in nanodroplet systems of gallium, EGaIn (75.5% gallium, 24.5% indium), and Galinstan (68.5% gallium, 21.5% indium, 10% tin). Field's metal (51% indium, 32.5% bismuth, 16.5% tin) is also investigated, which melts at ≈62 °C, as a contrast to the other systems. AFM measurements reveal distinct sub‐oxide nanostructured layering in all three RTLM systems, and Field's metal above the melting point, to differing degrees. EGaIn and Galinstan show multiple penetration events between 20 and 30 nm, with smaller, less complex events in Ga. MD simulations suggest that this layering is a result of the near‐surface ordering of LM atoms beneath the oxide layer. Importantly, the atoms in this region do not behave as solids but are more ordered than in a pure disordered liquid system. The surface nanostructure elucidated here significantly expands the understanding of LM systems and their behavior at interfaces. [ABSTRACT FROM AUTHOR]

Crystallization of alloys from a molten state is a fundamental process underpinning metallurgy. Here the direct imaging of an intermetallic precipitation reaction at equilibrium in a liquid‐metal environment is demonstrated. It is shown that the outer layers of a solidified intermetallic are surprisingly unstable to the depths of several nanometers, fluctuating between a crystalline and a liquid state. This effect, referred to herein as crystal interface liquefaction, is observed at remarkably low temperatures and results in highly unstable crystal interfaces at temperatures exceeding 200 K below the bulk melting point of the solid. In general, any liquefaction process would occur at or close to the formal melting point of a solid, thus differentiating the observed liquefaction phenomenon from other processes such as surface pre‐melting or conventional bulk melting. Crystal interface liquefaction is observed in a variety of binary alloy systems and as such, the findings may impact the understanding of crystallization and solidification processes in metallic systems and alloys more generally. [ABSTRACT FROM AUTHOR]

Significant progress has been made in recent years in the development of liquid metal alloy catalysts. This article provides an overview of the state‐of‐the‐art research pertaining to liquid metal alloy catalysis, including alloy synthesis, reactor design, and theoretical calculations. Different alloy synthesis methods are discussed with a focus on strategies that can achieve colloidal intermetallic structures in liquid metal alloys. Current reactors for liquid metal‐based electrocatalytic and thermochemical processes are summarized. The application of theoretical tools, such as machine learning and computational chemistry to further liquid metal alloy design, is discussed. Finally, an outlook on the technological challenges and our perspective on future research opportunities for liquid metal alloy catalysis are presented. [ABSTRACT FROM AUTHOR]

The emergence of liquid metal catalysts endows electrocatalytic processes with enhanced efficiencies by eliminating coking issues that rapidly deactivate conventional solid catalysts. Alloying them with trace amounts of redox-active metal additives can further improve their catalytic activity. Here we report a vanadium-liquid metal alloy with superior activity that can drive electrochemical reduction of CO2 into solid carbon. The reaction mechanism has been thoroughly investigated and discussed. In addition, artificial neural networks trained by machine learning have been demonstrated to be powerful in predicting performance of LM alloys with various compositions. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]