Figure 4 . (a) Limiting potential of the selected candidates
(Mn2@site1,
Ru2@site1,
Co2@site2,
W2@site2,
Os2@site3,
V2@site4,
Cr2@site4,
Ni2@site4,
W2@site4, and
Re2@site4, respectively. (b)-(e) Gibbs
free energy changes diagrams for
Co2@site2,
V2@site4, and
Cr2@site4, respectively.