Electron Redistribution Drives Structural Ordering in Sulfate (SO ₄ ) Adlayers

In this work, the coadsorption of SO 4 and H 2 O at the Au(111)‐electrolyte interface is investigated. It is uncovered how electron redistribution between coadsorbates correlates with the formation of tightly packed (√3a) SO 4 ‐adsorbate chains, which have been previously observed by Video‐scanning tunneling microscopy (STM) at potentials preceding the disorder‐order transition into (√3 × √7) SO 4 adlayers, as reported by Suto and Magnussen. Using density functional theory, ab initio molecular dynamics is combined with static ground‐state calculations to capture both the dynamic aqueous environment and the stability of coadsorbed SO 4 and H 2 O species. The analysis is extended to AuPdPt(111) solid solutions, where simple linear adsorbate scaling relations are employed to probe the electronic environments and hydrogen bond interactions between the coadsorbed species at the metal surfaces. Variations in these scaling trends are consistent with partial surface bond transfer between coadsorbed SO 4 and H 2 O, increasing the stability of such adsorbate configurations. Multiple unique adsorbate structures are consided, of which the √3a chains, previously observed by Video‐STM, emerge as the most favorable pretransition configuration because they maximize the number of SO 4 –H 2 O interactions and thus the extent of surface bond transfer as highlighted by the scaling trends.