Electrochemically Formed Submicrometer Liquid Metal Alloy Wires: A Route toward High-Surface-Area Electrochemical Electrodes

Abstract

Electrochemical control of interfacial tension enables the extrusion of gallium-based liquid metals into high-surface-area nonspherical geometries relevant to electrocatalysis and hydrogen production. Here, liquid metal wires with diameters down to ∼500 nm are produced using quartz nanopipettes under moderate anodic polarization in an alkaline electrolyte. A morphology map identifies the operating window for continuous wire formation, distinct from droplet and blob regimes. The current response displays a previously unreported transient behavior, reaching three distinct maximum current density levels depending on the wire residence time. A model coupling the time-dependent liquid metal/electrolyte interfacial area with kinetic current density expressions accurately reproduces the transients and yields steady-state current densities, relaxation time constants, and an effective interfacial pseudocapacitance. Oxidation charge analysis reveals three distinct initial oxide growth rates, consistent with the characteristic residence time regimes, while kinetic analysis quantifies the corresponding oxide-induced overpotential losses. These results define a practical lower size limit of ∼500 nm for electrochemical liquid metal wire fabrication and establish a quantitative framework for their use in high-surface-area electrochemical reactors.