Developing Interface Force Fields for Water and Oxygen on Pt, and <i>Pt</i> _<i>3</i> <i>Ni</i> , <i>Pt</i> _<i>3</i> <i>Co</i> Alloy Surfaces for Proton-Exchange Membrane Fuel Cell (PEMFC) Applications

Interface force fields (IFFs) are crucial for the atomistic modeling of PEMFC interfaces. We benchmark ten optimization algorithms and four force-field forms against DFT adsorption energies and forces and present a framework for selecting the algorithm/force-field combination. At Pt-H₂O, the best IFF yields a mean absolute error (MAE) of 0.32 eV for adsorption energy and 0.12 eV/Ų for forces, cutting energy error by 70-90% and force error by 44-48% compared to COMB3, ReaxFF, and LJ mixing. Similar improvements are observed for Pt₃Ni-H₂O and Pt₃Co-H₂O. For Pt/Pt₃Ni/Pt₃Co-O₂, energy MAEs are 0.30-0.68 eV and force MAEs are 0.42-0.85 eV/Ų; errors are larger for force components parallel to the surface, while normal components remain well captured, reflecting the challenges of describing O₂ dissociation on (111) metal surfaces using classical force fields. The framework enables data-efficient IFF development and guides the selection of force-field forms and optimization algorithms for PEMFC and interfacial simulations.