Liquid-cell transmission electron microscopy (LCTEM) has opened up a new way to study chemical reactions at the interface between solids and liquids. However, understanding the effects of the electron beam in the liquid cell has been clearly identified as one of the most important challenges to assess correctly and quantitatively LCTEM data. Here we show that the electron beam can be used to drive reversible deposition/dissolution cycles of copper shells over gold nanoparticles in methanol. Besides revealing the influence of irreversible processes on the kinetic of growth/etching cycles, this study of nanostructure behaviour as a function of the dose rate highlights the possibility to switch the oxidising or reducing nature of liquid environment only with the electron beam. The chemical and electronic processes possibly involved in these tunable redox reactions are qualitatively discussed together with their possible impacts on electrochemical LCTEM experiments.
Beam induced deposition and dissolution of metallic copper from solution onto gold nanoparticles was induced by cycling between high and low electron dose rates. The high electron dose rate is believed to lead to a predominantly reducing effect due to a high concentration of solvated electrons, while at low doses the oxidizing species, CHOH∙, predominates.