Fig. 5: Trimetallic SAA M₁-M₂-Ni catalysts segregation and relative site occupation tendency.

a segregation energy (\(\Delta {E}_{{seg}}\)) in eV calculated for trimetallic M₁-M₂-Ni combinations in a vacuum and under the effect of H^*-induced environment. Insets: top and side views of the bulk to surface segregation for the vacuum (blue borders) and H*-induced (yellow borders) systems. b side view of different atomic coordination of M₁-M₂-Ni tested for the Zn-Au-Ni catalyst and their c calculated \(\Delta {E}_{{seg}}\). d difference in the 1^st nearest neighbor site (NNS) and 2^nd NNS surface energy (\({\gamma }_{{1}^{{st}}{NNS}}-{\gamma }_{{2}^{{nd}}{NNS}}\)) for the M₁-M₂-Ni combinations. \({\gamma }_{{1}^{{st}}{NNS}}-{\gamma }_{{2}^{{nd}}{NNS}}\le 0{\rm{J}}.{{\rm{m}}}^{-2}\) denoted by green triangles indicate that the 1^st NNS is relatively more stable than the 2^nd NNS ensemble. Nearly stable 1^st NNS are marked with yellow circles and hold \({\gamma }_{{1}^{{st}}{NNS}}-{\gamma }_{{2}^{{nd}}{NNS}}\) in the range of \(0-0.025{\rm{J}}.{{\rm{m}}}^{-2}\), while structures with \( > 0.025\,{\rm{J}}.{{\rm{m}}}^{-2}\) signals that 2nd NNS is thermodynamically more favorable than 1^st NNS indicated with blue diamonds. Insets reveal the top view of the 1^st NNS and 2^nd NNS trimetallic surfaces. Data are available in Zenodo.