Interfacial Engineering of Room Temperature Liquid Metals

Abstract

and formed spontaneously and instantaneously upon exposure to atmospheric oxygen. [1-3] The thin film or "protective skin" covering the surface of RTLMs, generally dominated the physical properties and applications of the materials. This thin film is composed of a majority fraction of gallium oxides with a much smaller amount of indium and tin oxides. [4] When immersed in acidic or alkaline electrolytes, the oxidic films of RTLMs will be dissolved. [5-8] Due to the disorder of internal structure, the surface of the spherical liquid metal droplet is smooth and removable under the function of surface tension. [9,10] According to the size and structure of the solid substrate, the contact areas between the liquid metal and the solid substrate shows various wetting phenomena and corresponding application scenarios. [11-14] Surface chemical composition plays the primary role in dominating various phenomena and practical applications of RTLMs, which possessed the technologically important and scientifically interesting parameter. Gallium-based liquid metal is similar in structure to conventional solid metal, except for some covalent bonds inside, and the physicochemical properties have the commonality of both metallic solid and fluid properties. [15] The composition of gallium-based alloys can be assumed as made up of several atomic groups, within which the permutation of the solid remains, the binding energy between the liquid atoms remains strong, but the binding force between the groups was broken. The interface refers to the contact area between the different phases, which is the transition layer from one phase to another. The binding force of electrons that are relatively far away from the inner core is related to their energy, causing the interface behavior between different phases to be incompletely consistent. The surface is a type of interface, which specifically refers to the gas phase substance in interfacial behavior. In the processes of thermodynamics, [16,17] surface absorption, [18,19] controllable wetting, [6,13,20] material catalysis, [21,22] redox, and other physical and chemical reactions, [23,24] RTLMs inevitably contact with other substances with different phase states. Even the pure liquid metal would contact with oxygen in the air to yield a thin protective film. [17,25,26] Therefore, the investigation of interfacial behaviors between RTLMs and different surrounding mediums is helpful to renovate and broaden the understanding and applications of liquid metal. So far, there gradually appeared literature on phenomena and mechanism of the interfacial effect of RTLMs, such as synthesis of low-dimensional materials in the gas atmosphere, [27,28] Room temperature liquid metals (RTLMs), especially those made of galliumbased alloys belong to an emerging versatile material with fascinating characteristics derived from its simultaneous metallic and inherent fluidic natures. The interfacial effects of liquid metal involved in diverse surfaces thus play critical roles in explaining many fundamental phenomena....

Liquid metals: an ideal platform for the synthesis of two-dimensional materials

“…25,26 Interestingly, the oxide layer that forms on the surface of EGaIn is found to be composed of gallium oxide. 27,28 The preferential growth of gallium oxide is due to the more favourable Gibbs free energy of oxide formation for gallium when compared with indium. By exploiting this concept, elements with thermodynamically more favourable oxide formations can be alloyed into gallium-based liquid metals to produce oxides of the dissolved elements.…”

Sequential Oxidation Strategy for the Fabrication of Liquid Metal Electrothermal Thin Film with Desired Printing and Functional Property

“…Due to the tunneling effect, the electrons in the liquid metal inner core would be transferred to the surface of the absorbed oxygen atoms [37,38]. The thickness of surface oxidation is 0.5~3 nm under the process of static condition without external disturbance, which prevented the further internal oxidation and provided a functional mechanical skin, approximately charactering from following equation [38][39][40][41],…”

Doping Process of 2D Materials Based on the Selective Migration of Dopants to the Interface of Liquid Metals

“…Liquidmetalbased processes offer a practical solu tion in this regard. [1][2][3][4][5][6][7][8][9][10][11][12][13] In a liquid metal alloy, individual elements naturally compete to appear on the surface [14] and this likely offers a very efficient filter at the elemental level. Zavabeti et al [14] have shown that even very small amounts of elements such as Al, Gd and Hf, added to the bulk of liquid metal such as Ga, can dominate the surface in the liquid state.…”