An insight into the
electrochemical stability of Mg surfaces is
of practical importance for improving the corrosion resistance of
Mg as well as its performance as a battery electrode. The present
paper employs first-principles density functional theory simulations
to study the electrochemical stability of magnesium surfaces in aqueous
environments. A number of electrochemical reactions that describe
the interactions between the Mg(0001) surface and water were analyzed.
It was verified that water dissociation is favored upon the Mg surface,
in agreement with recent works; however, it is also shown that the
previously unstudied Heyrovsky reaction may play an important role
in controlling the surface stability. Furthermore, it was found that
the surface stability also crucially depends on the concentration
of adsorbed hydroxyl groups. Specifically, the surface work function
was determined to vary as the function of hydroxyl coverage, which
has ramifications for the catalytic behavior of the Mg surface. The
influences of surface doping with Ca (a reactive element) and Fe (a
comparatively noble element) were also studied to provide an atomic-level
understanding of how the dopants influence surface properties and
subsequent electrochemical reactions. With a keen recent empirical
interest in Mg surface stability given the industrial relevance of
Mg, the present study provides key new insights into the physical
processes related to the enhanced catalytic activity of Mg and its
alloys
