Anodic activation of Mg in the presence of In3+ ions in dilute sodium chloride solution

Pure magnesium reveals a previously unreported combination of enhanced anodic kinetics and unaltered cathodic kinetics in 0.1 M sodium chloride in the presence of 1 mM indium chloride. The corrosion potential of magnesium is lower than the electrode potential for indium/indium (+3) ions equilibrium causing deposition of indium on the magnesium surface. X-ray photoelectron spectroscopy confirms the presence of indium species on the magnesium surface. Despite the 1 millimolar indium chloride + 0.1 M sodium chloride solution exhibiting an acidic pH close to 4, the hydrogen evolution kinetics on magnesium remains close to that of the 0.1 M sodium chloride of near neutral pH indicating an inhibitive effect of indium on hydrogen evolution. On the contrary, the presence of 1 millimolar indium ions in 0.1 M sodium chloride has increased the anodic dissolution of Mg. The former is expected to result in higher magnesium anode efficiencies and the latter, high anode current output. Thus, the electrochemical characteristics exhibited by pure magnesium in 1 millimolar indium chloride +0.1 M sodium chloride solution have implications on magnesium as an anode, which is relevant in the context of higher performance and stable aqueous primary magnesium batteries.