Computationally Assisted XPS Allows the Decoding of Surface Intermediates Involved in Ethylene Epoxidation

In this work, density functional theory simulations are combined with X-ray photoelectron spectroscopy (XPS) to systematically investigate the chemical structures of carbon- and oxygen-containing surface species relevant to ethylene epoxidation on silver catalysts. Core-level binding energies are calculated within a density functional theory framework using the transition-potential method to predict C 1s and O 1s shifts for adsorbed species, including hydrocarbons, carbon oxygenates, and key reaction intermediates. By rigorously validating the computational protocol against experimentally measured binding energies, we achieve reliable spectral assignments and establish quantitative relationships between local O and C chemical environments and their XPS signatures. The resulting structure–reactivity correlations provide new mechanistic insight into the evolution of oxygen and carbon species under reaction conditions and their role in controlling epoxidation selectivity. Beyond elucidating key surface reaction pathways for ethylene epoxidation, this integrated experimental–theoretical framework offers transferable guidelines for the quantitative XPS analysis of surface chemistry in heterogeneous catalysis.