Fig. 1: Potential dependent segregation and aggregation grand free energies for the SAAs.
a Schematic showing dopant segregation (top) and aggregation (bottom) over a bare X1Cu(111) surface, along with the equations to compute bare surface segregation and aggregation grand free energies, ΔΦseg(U) and ΔΦagg(U), as well as adsorbate-induced segregation and aggregation grand free energies, \(\Delta {{\varPhi} }_{{{{\rm{seg}}}}}^{{{{\rm{A}}}}^* }(U)\) and \(\Delta {{\varPhi} }_{{{{\rm{agg}}}}}^{{{{\rm{A}}}}^* }(U)\). Here, \(\Delta \Delta {{\varPhi} }_{{{{\rm{ads,1:2}}}}}^{{{{\rm{A}}}}^* }\) is the adsorption-free energy difference between system 1 and system 2. Segregation and aggregation free energies for 8 Cu-based SAAs with (b) a bare surface, (c) adsorbed hydrogen (H*), and (d) adsorbed nitrate (\({{{{\rm{NO}}}}}_{3}^{* }\)). Segregation free energy is indicated by the bar value, where values above zero signify stability on the surface. Aggregation free energy is indicated by the bar color, where values above zero (red) signify stability as a single dopant. Free energies were calculated at −0.714 V and 0.114 V (striped) using the eGC-DFT method. For \({{{{\rm{NO}}}}}_{3}^{-}\) adsorption on Pt1Cu and Au1Cu, a white colored bar or the absence of any bar indicates that \({{{{\rm{NO}}}}}_{3}^{-}\) would not adsorb on the site. The schematics in each figure show the expected SAA structure depending on the segregation and aggregation free energies. The data used in creating these figures is in Supplementary Tables 1-3.
