Recent applications of liquid metals featuring nanoscale surface oxides

Abstract

This proceeding describes recent efforts from our group to control the shape and actuation of liquid metal. The liquid metal is an alloy of gallium and indium which is non-toxic, has negligible vapor pressure, and develops a thin, passivating surface oxide layer. The surface oxide allows the liquid metal to be patterned and shaped into structures that do not minimize interfacial energy. The surface oxide can be selectively removed by changes in pH or by applying a voltage. The surface oxide allows the liquid metal to be 3D printed to form free-standing structures. It also allows for the liquid metal to be injected into microfluidic channels and to maintain its shape within the channels. The selective removal of the oxide results in drastic changes in surface tension that can be used to control the flow behavior of the liquid metal. The metal can also wet thin, solid films of metal that accelerates droplets of the liquid along the metal traces .Here we discuss the properties and applications of liquid metal to make soft, reconfigurable electronics.

Liquid Metals in Catalysis for Energy Applications

“…Nonetheless, surface oxides can be easily mitigated by changing the pH of the solution, applying a reducing potential through the electrode or working in inert environments. 47,48 This phenomenon can be exploited to advance controllable flow behaviors in microfluidic devices and electrochemical cells. 47,49 Furthermore, manipulating surface oxides can be an effective method of controlling LM fluidity, by reducing the viscosity of LMs without the need of a heat source.…”

“…47,48 This phenomenon can be exploited to advance controllable flow behaviors in microfluidic devices and electrochemical cells. 47,49 Furthermore, manipulating surface oxides can be an effective method of controlling LM fluidity, by reducing the viscosity of LMs without the need of a heat source. 50 The effect of the presence of surface oxides on the LM viscosity is illustrated in Figure 4A.…”

“…Fixed-bed reactors are versatile conventional designs that have been extensively used in many energy-related LM catalytic applications. 47,[85][86][87][88] Fixed-bed reactors provide high single pass conversion per unit of catalyst mass; however, they exhibit nonuniform temperature distribution and unfavorable heat transfer. Moreover, microchannel reactors are utilized in methanol steam reforming.…”

“…138,139 The surface oxide layer can also be used for the shaping of LM into complex three-dimensional (3D) structures favorable to electrocatalyst processes. 47 Taking advantage of the stabilization effect of the EGaIn oxide layer, complex free-standing LM electrode systems were developed using 3D printing techniques, as illustrated in Figure 10E. 5,47,54 The LM electrocatalysis field has recently witnessed a shift of direction from the traditional use of toxic mercury to low-toxicity room-temperature Ga-based LMs and ALMs.…”

“…47 Taking advantage of the stabilization effect of the EGaIn oxide layer, complex free-standing LM electrode systems were developed using 3D printing techniques, as illustrated in Figure 10E. 5,47,54 The LM electrocatalysis field has recently witnessed a shift of direction from the traditional use of toxic mercury to low-toxicity room-temperature Ga-based LMs and ALMs. Current trends show increasing attempts to expand on promising LM candidates, either by further introducing catalytic elements to the existing LMs or by exploring other low-melting-point alloys.…”