Control of electrochemical reactions in liquid cell electron microscopy via a redox additive approach

A fundamental understanding of the structural dynamics that occur during electrochemical reactions is required in order to further improve electrochemical technologies. Liquid cell electron microscopy has emerged as a powerful technique that can probe the structural dynamics of nanocrystal systems at near-atomic resolution in a liquid environment. However, the technique has been limited due to uncontrolled radical formation from interactions between the microscope’s electron beam and the liquid medium. Here we demonstrate that redox additives can efficiently scavenge radicals generated during liquid cell electron microscopy studies. The scavenging process results in the formation of well-defined redox couples that enable the study of electrochemical reactions with precise potential control. The etching of noble metal nanocrystals in chloride-containing solutions was used as a chemical probe to determine the electrochemical reactivity of the liquid cell environment. The redox additive approach was implemented with nine redox species/nanocrystal combinations, with all cases exhibiting etching behavior consistent with electrochemical principles. The ability to study electrochemical reactions at near-atomic resolution will allow liquid cell electron microscopy to become an invaluable tool for analytical electrochemistry.