title: Revisiting the electrochemical impedance spectroscopy of magnesium with online inductively coupled plasma atomic emission spectroscopy.
abstract: The electrochemical impedance of reactive metals such as magnesium is often complicated by an obvious inductive loop with decreasing frequency of the AC polarising signal. The characterisation and ensuing explanation of this phenomenon has been lacking in the literature to date, being either ignored or speculated. Herein, we couple electrochemical impedance spectroscopy (EIS) with online atomic emission spectroelectrochemistry (AESEC) to simultaneously measure Mg-ion concentration and electrochemical impedance spectra during Mg corrosion, in real time. It is revealed that Mg dissolution occurs via Mg(2+) , and that corrosion is activated, as measured by AC frequencies less than approximately 1 Hz approaching DC conditions. The result of this is a higher rate of Mg(2+) dissolution, as the voltage excitation becomes slow enough to enable all Mg(2+) -enabling processes to adjust in real time. The manifestation of this in EIS data is an inductive loop. The rationalisation of such EIS behaviour, as it relates to Mg, is revealed for the first time by using concurrent AESEC.
authors.affiliation: Chimie ParisTech, Ecole Nationale Supérieure de Chimie de Paris, 11 Rue Pierre et Marie Curie, Paris 75005 (France).
authors.forename: Viacheslav
authors.initials: V
authors.lastname: Shkirskiy
authors.forename: Andrew D
authors.initials: AD
authors.lastname: King
authors.forename: Oumaïma
authors.initials: O
authors.lastname: Gharbi
authors.forename: Polina
authors.initials: P
authors.lastname: Volovitch
authors.forename: John R
authors.initials: JR
authors.lastname: Scully
authors.forename: Kevin
authors.initials: K
authors.lastname: Ogle
authors.forename: Nick
authors.initials: N
authors.lastname: Birbilis
keywords: ICP-AES; corrosion; electrochemistry; impedance spectroscopy; magnesium