Electrochemical detection of univalent Mg cation: A possible explanation for the negative difference effect during Mg anodic dissolution

Although the existence of short-lived univalent magnesium cation (Mg+) was supposed to play an important role on negative difference effect (NDE) during anodic dissolution of magnesium in previous work, no direct proof of the existence of Mg+ has ever been reported. Here, a modified substrate generation/tip collection mode of scanning electrochemical microscopy was applied to detect Mg+ via the reaction of generated Mg+ and potassium ferricyanide (K3[Fe(CN)6]). Based on the new design method and experimental data, our studies provide a direct evidence of the presence of Mg+ in aqueous solution combining with open circuit and polarization condition, which is benefit to understand NDE.