Differences in solvation thermodynamics of oxygenates at Pt/Al₂O₃ perimeter versus Pt(111) terrace sites

RAG Carcamo and XH Zhang and A Estejab and JR Zhou and BJ Hare and C Sievers and S Sarupria and RB Getman, ISCIENCE, 26, 105980 (2023).

DOI: 10.1016/j.isci.2023.105980

A prominent role of water in aqueous-phase heterogeneous catalysis is to modify free energies; however, intuition about how is based largely on pure metal surfaces or even homogeneous solutions. Using multiscale modeling with explicit liquid water molecules, we show that the influence of water on the free energies of adsorbates at metal/support interfaces is different than that on pure metal sur-faces. We specifically compute free energies of solvation for methanol and its constituents on a Pt/AI(2)O(3) catalyst and compare the results to analogous values calculated on a pure Pt catalyst. We find that the more hydrophilic Pt/Al2O3 inter-face leads to smaller (more positive) free energies of solvation due to an increased entropy penalty resulting from the additional work necessary to disrupt the interfacial water structure and accommodate the interfacial species. The results will be of interest in other fields, including adsorption and proteins.

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