Localized Alkaline\nEnvironment via In Situ Electrostatic\nConfinement for Enhanced CO<sub>2</sub>‑to-Ethylene Conversion\nin Neutral Medium

Electrocatalytic CO₂ reduction reaction (CO₂RR) is one of the most promising routes to facilitate carbon\nneutrality.\nAn alkaline electrolyte is typically needed to promote the production\nof valuable multi-carbon molecules (such as ethylene). However, the\nreaction between CO₂ and OH^– consumes\na significant quantity of CO₂/alkali and causes the rapid\ndecay of CO₂RR selectivity and stability. Here, we design\na catalyst–electrolyte interface with an effective electrostatic\nconfinement of in situ generated OH^– to improve\nethylene electrosynthesis from CO₂ in neutral medium. In\nsitu Raman measurements indicate the direct correlation between ethylene\nselectivity and the intensities of surface Cu–CO and Cu–OH\nspecies, suggesting the promoted C–C coupling with the surface\nenrichment of OH^–. Thus, we report a CO₂-to-ethylene Faradaic efficiency (FE) of 70% and a partial current\ndensity of 350 mA cm^–2 at −0.89 V vs the\nreversible hydrogen electrode. Furthermore, the system demonstrated\na 50 h stable operation at 300 mA cm^–2 with an average\nethylene FE of ∼68%. This study offers a universal strategy\nto tune the reaction micro-environment, and a significantly improved\nethylene FE of 64.5% was obtained even in acidic electrolytes (pH\n= 2).