Preferential Electroreduction at the Oil|Water|Conductor Interface

Chemistry in confined volumes, such as aqueous droplets, is different from bulk,continuous water. However, few techniques are available to probe interfacial reactivity in complex,multiphase environments. Here, we demonstrate preferential electroreduction at the oil|water|conductor(three-phase) interface. Electrodeposition of cobalt and nickel results in ringlike structures that can becharacterized with tens of nanometers precision in scanning electron microscopy and energy dispersiveX-ray spectroscopy. To demonstrate the generalizability of these observations, we show thatelectroreduction of resazurin tofluorescent resorufin occurs preferentially at the three-phase boundary.The preferential electroreduction does not depend on droplet geometry. These results, grounded inthree-phase boundary reactivity, are highly important across allfields of chemistry and biology becausethey highlight how the interface can change chemistry in unexpected ways

Automated summary

Chemistry in confined volumes differs from bulk reactions. Preferential electroreduction at the three-phase interface is observed and shown to be independent of droplet geometry.