Localized Alkaline Environment via In Situ Electrostatic Confinement for Enhanced CO₂-to-Ethylene Conversion in Neutral Medium

Abstract

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

Proton Shuttling by Polyaniline of High Brønsted Basicity for Improved Electrocatalytic Ethylene Production from CO2

“…It was intriguing to see that only the band of HCO 3 − , instead of CO 3 2− , was detected in the serial Raman spectra of PANI@HKUST (Figure 4f). Previous studies have often associated the enhanced hydrocarbon production with high local pH due to the suppressed HER, and the high local pH with CO 3 2− due to the aforementioned equilibrium: HCO 3 − (aq)+OH − (aq)↔CO 3 2− (aq)+H 2 O [9b,30b] . However, our Raman study here only picked up the HCO 3 − signal at the PANI/Cu interface, which, as a matter of fact, yielded a significantly higher partial current density of ethylene.…”

Acidic Electrocatalytic Semihydrogenation of Alkynols to Alkenols on Copper Phosphide at Industrial‐Level Current Density

“…In the past decade, electrocatalytic hydrogenation with water as the hydrogen source under mild conditions has rapidly emerged as a promising alternative to conventional thermocatalytic hydrogenation using pressurized hydrogen. [ 1 ] For instance, CO 2 and CO have been electrochemically hydrogenated into C 1‐2 and C 2+ feedstocks [ 2‐6 ] ( e.g ., formate, methane, ethylene, ethanol, etc .) in aqueous electrolytes.…”

Organic-moiety-engineering on copper surface for carbon dioxide reduction

“…The tuneable and well-defined chemical structure of molecules and polymers provide more possibilities for tuning and mechanistic studies of catalytic activity. [35][36][37]…”