Understanding the enhanced rates of hydrogen evolution on dissolving magnesium

Despite the growing interest in Mg and its alloys, their use has been largely limited due to their high reactivity in aqueous environments. Improving the understanding of the basic principles of Mg corrosion represents the first step to explain and, eventually, improve the corrosion behaviour of Mg alloys. Herein an original mechanistic surface kinetic DFT model that clarifies the mechanism of anomalous HE on anodically polarised Mg is presented. In accordance with several experimental observations, this model describes anomalous HE proceeding at the regions dominated by anodic dissolution via the reaction of an Mg*H intermediate with water. The Mg*H intermediates undergo oxidation upon anodic polarisation, resulting in hydrogen evolution and Mg dissolution. Furthermore, it is revealed that increasing rates of an electrochemical cathodic reaction are possible within a dissolving anode.