Fig. 3

The experimental (Expt) Pourbaix diagrams (\([I] = 10^{ - 6}\) M) and DFT Pourbaix diagrams (\([I] = 10^{ - 6}\) and 10−2 M). The two inclined parallel blue dashed lines indicate the electrode potentials for the oxidation (\(2{\mathrm{H}}_2{\mathrm{O}} - 4e^ - \to {\mathrm{O}}_2 + 4{\mathrm{H}}^ +\), upper) and reduction (\(2{\mathrm{H}}_2{\mathrm{O}} + 2e^ - \to {\mathrm{H}}_2 + 2{\mathrm{OH}}^ -\), lower) of water. The phase domains for some secondary phases (e.g., Cr2O3, Mn2O3, Fe2O3, FeO, Co(OH)2, and Ni(OH)2 as labeled in brackets) are also indicated by their red dotted boundaries