Chemical reactivity of Ga-based liquid metals with redox active species and its influence on electrochemical processes

Room temperature liquid metals based on gallium demonstrate interesting physical and chemical properties when placed in electrochemical environments. In this work we explore the applicability of hanging liquid metal droplets as electrode materials for simple surface insensitive and surface sensitive electron transfer reactions, namely the electrochemical reduction of [Ru(NH3)6]3+ and [Fe(CN)6]3− ions in solution. Significantly we found that for both redox species the electron transfer process was impeded at galinstan (68.5% Ga, 22.5% In and 10% Sn). This is related to the chemical reactivity of the Ga component which is oxidised when exposed to aqueous solutions of [Ru(NH3)6]3+ and [Fe(CN)6]3− to generate the reduced form of the redox mediator. For the former this results in the production of Ru-red and Ru-brown cationic trimers in solution as well as gallium oxide on the surface of the liquid metal, and in the latter case the formation of solid Prussian Blue

Electrochemical restructuring of Gold electrodes with redox active species to create electrocatalytically active nanostructured surfaces

Electrochemical potential cycling of gold electrodes in commonly used redox active species to produce a nanostructured surface is introduced. A commercially available gold electrode when cycled in three redox active species including hexaammine ruthenium chloride, ferrocene methanol and ferricyanide shows rapid conversion of the surface into a nanostructured form within 50 cycles which usually requires hundreds of cycles in their absence. The active gold nanostructured electrode was characterized by cyclic voltammetry in acidic and alkaline electrolyte indicating the presence of different basal sites depending on the redox species employed. In addition, the active gold nanostructured surface shows higher electrocatalytic activity than the pristine polycrystalline gold electrode for glucose and ascorbic acid oxidation in alkaline media.</p

Using H2O2 as a green oxidant to produce fluorescent GaOOH nanomaterials from a liquid metal

We report a simple and rapid method for the synthesis of fluorescent gallium oxyhydroxide (GaOOH) nanoparticles from liquid Ga by a probe sonication method in the presence of H2O2 as an oxidant. The aspect ratio of the GaOOH nanoparticles is determined by the concentration of H2O2 and solution pH, as well as the probe energy and sonication time. Further surface modification with cyclodextrin to achieve biocompatibility for potential biomedical applications is reported where an example of cell uptake and fluorescence imaging is shown.</p