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.