Tailoring Solvent-Mediated CO2 Reservoirs at Heterointerfaces for Enhanced Electrochemical CO2-to-C2H4 Conversion

Transforming waste CO2 into value-added fuels and chemicals, while simultaneously enabling renewable electricity storage, presents a viable strategy for achieving a sustainable energy economy. However, efficient conversion to C2+ products remains challenging, primarily due to the low CO2 concentration at the catalyst surface in aqueous environments. Herein, we addressed this issue by designing Cu2O-MgO catalysts with abundant nanointerfaces serving as effective CO2 reservoirs under aqueous conditions. Ab initio molecular dynamics simulations demonstrated that these interfaces substantially enhanced the CO2 stabilization at the surface, effectively inhibiting their displacement by interfacial water molecules. This localized CO2 enrichment facilitated C–C coupling kinetics and selectively promoted the formation of target products. Building on these findings, we synthesized a model catalyst featuring abundant Cu2O-MgO nanointerfaces and evaluated its performance in aqueous media. Remarkably, flowing electrolyzer tests demonstrated a Faradaic efficiency of 67% for ethylene at a current density of ∼ 240 mA·cm–2. Subsequent mechanistic investigations combining spectroscopy experiments and theoretical calculation simulations demonstrated that the surface-enriched CO2 enhanced the CO* coverage at the Cu active sites, thereby promoting ethylene production through facilitated C–C coupling. This study pioneers the rational design of heterogeneous catalysts for selective CO2RR toward value-added chemicals with potential applications extending to diverse electrocatalytic processes.