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.
Planet‐like liquid metal‐based nanostructures are produced using a high temperature sonication method that is carried out in a molten‐salt sodium acetate environment. The obtained particles feature an oxide crust, liquid mantle and a solid core, and have promising properties for applications in catalysis.
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.
Atomic force microscopy and molecular dynamics simulations reveal distinct sub‐oxide nanostructured layering in room‐temperature liquid metals.
The rise of antibiotic resistance in pathogenic bacteria requires new therapeutics to be developed. Several metallic nanoparticles such as those made from silver, copper, and zinc have shown ...significant antibacterial activity, in part due to metal ion leaching. Ga3+ containing compounds have also been shown to have antibacterial properties. Accordingly, it is estimated that metallic Ga droplets may be antibacterial, and some studies to date have confirmed this. Here, multiple concentrations of Ga droplets were tested against the antibiotic resistant Gram-positive bacteria methicillin-resistantStaphylococcus aureus (MRSA) and the Gram-negative bacteria Pseudomonas aeruginosa (P. aeruginosa) Despite a high concentration (2 mg/mL), Ga droplets had only modest antibacterial activity against both bacteria after 24 h of interaction. Finally, we demonstrated that Ga droplets were easily functionalized through a galvanic replacement reaction to develop antibacterial particles with copper and silver demonstrating a total detectable reduction of MRSA and >96% reduction ofP. aeruginosa. Altogether, these results contradict previous literature and show that Ga droplets demonstrate no antibacterial activity at concentrations comparable to those of conventional antibiotics and well-established antibacterial nanomaterials and only modest antibacterial activity at very high concentrations. However, we demonstrate that their antibacterial activity can be easily enhanced by functionalization.
Structural Evolution of Liquid Metals and Alloys Krishnamurthi, Vaishnavi; Vaillant, Pierre H. A.; Mata, Jitendra ...
Advanced materials (Weinheim),
07/2024, Letnik:
36, Številka:
30
Journal Article
Recenzirano
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Low‐melting liquid metals are emerging as a new group of highly functional solvents due to their capability to dissolve and alloy various metals in their elemental state to form solutions as well as ...colloidal systems. Furthermore, these liquid metals can facilitate and catalyze multiple unique chemical reactions. Despite the intriguing science behind liquid metals and alloys, very little is known about their fundamental structures in the nanometric regime. To bridge this gap, this work employs small angle neutron scattering and molecular dynamics simulations, revealing that the most commonly used liquid metal solvents, EGaIn and Galinstan, are surprisingly structured with the formation of clusters ranging from 157 to 15.7 Å. Conversely, noneutectic liquid metal alloys of GaSn or GaIn at low solute concentrations of 1, 2, and 5 wt%, as well as pure Ga, do not exhibit these structures. Importantly, the eutectic alloys retain their structure even at elevated temperatures of 60 and 90 °C, highlighting that they are not just simple homogeneous fluids consisting of individual atoms. Understanding the complex soft structure of liquid alloys will assist in comprehending complex phenomena occurring within these fluids and contribute to deriving reaction mechanisms in the realm of synthesis and liquid metal‐based catalysis.
This study, using small angle neutron scattering and molecular dynamics simulations, uncovers the structured nature of commonly used liquid metal solvents such as EGaIn and Galinstan even under high temperatures. This contradicts the previous belief of their homogenous fluidity and contrasts their absence in 1, 2 and 5 wt% GaSn, 1, 2 and 5 wt% GaIn, and Ga.
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.
This review establishes a systematic discussion on the challenges of liquid alloys catalysis, including the synthesis of alloys, reactor design, material selection, electrocatalytic, and thermocatalytic processes as well as artificial intelligence (AI) and machine learning (ML) tools.
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.
The phenomenon of solid metal surface liquefaction within liquid metal environments, represents an intriguing equilibrium state, defying common expectations by oscillating between a solid and liquid phase at temperatures significantly below the intermetallic compounds' conventional melting point. This discovery promises to advance the understanding of fundamental chemistry in metallic systems, offering insights into their behavior and potential applications.
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.
A toolbox for investigating liquid metal systems Krishnamurthi, Vaishnavi; Parker, Caiden J.; Nguyen, Chung Kim ...
Cell reports physical science,
02/2024, Letnik:
5, Številka:
2
Journal Article
Recenzirano
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The exceptional properties of liquid metals at room temperature, such as their fluidity, stretchability, deformability, and potential applications, have rapidly inspired the scientific community. At ...present, the main challenge is overcoming technical barriers associated with the characterization of liquid metal systems, which have resulted in their molecular structure remaining effectively unknown. This lack of knowledge has significantly hampered the progress of the emerging field of liquid metal chemistry, prohibiting tailored design and relegating researchers to work by trial and error. In recent years, several technological and scientific developments, including improved analytical tools, have emerged that have the potential to tackle the current challenges. In this review, we present a comprehensive appraisal of the various state-of-the-art characterization techniques that can help uncover answers to long-standing questions in the domain of liquid metals and metal-in-metal colloidal systems. We describe selected generic methodologies and several unique approaches that can capture the various changes in the physical and chemical behavior of molten metals in the presence of internal and external stimuli. In combination, the outlined tools will deepen our understanding of liquid metal chemistry and will accelerate research translation to provide solutions in areas such as catalysis, biomedicine, and reconfigurable electronics.
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The presence of metallic bonds has made it challenging to comprehend the chemistry within liquid metals using light-based characterization techniques. In this review, Krishnamurthi et al. assess the latest methods to comprehend the physical and chemical changes in liquid metals through advancements in electron, neutron, and X-ray spectroscopy and scattering techniques.
