Selectivity Maps for Electrochemical Ethylene Oxidation to Ethylene Oxide and Ethylene Glycol

Abstract

Electrochemical ethylene oxidation can produce ethylene oxide and ethylene glycol, but selectivity is limited by competition with the oxygen evolution reaction and overoxidation. At the same time, the mechanistic literature is fragmented across oxo-, peroxo-, and hydroxyl-mediated pathways, creating ambiguity and hindering systematic improvement. Using density functional theory (DFT) and scaling relations, we build a unified descriptor-based framework comparing the three pathways across fcc metals, metal(II) oxides, and rutile-structured oxides. The oxygen binding strength is found to control ethylene activation via oxo and peroxo species, while a carbon-based descriptor describes the hydroxyl pathway, and product binding defines an overoxidation limit. The resulting selectivity maps identify the catalyst properties required for each route, rationalize the high performance of individual catalysts such as oxidized Pd, and provide transferable guidelines for designing selective alkene oxidation catalysts.