Crown ether functionalization boosts CO₂ electroreduction to ethylene on copper-based MOFs

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Carbon dioxide (CO2) electroconversion is crucial for sustainable energy and environmental remediation.
• Copper-based metal-organic frameworks (MOFs) show potential for CO2 reduction but require optimization for selectivity.
• Ethylene (C2H4) is a valuable chemical feedstock produced via CO2 electroconversion.

Purpose of the Study:

• To investigate the effect of crown ether (CE) modification on the performance of copper-based MOFs for CO2 electroconversion to ethylene.
• To enhance the selectivity and faradaic efficiency (FE) of ethylene production.
• To elucidate the mechanism behind CE-enhanced catalytic activity.

Main Methods:

• Synthesis and characterization of crown ether-modified copper-based MOFs (CuBTC, CuBDC, CuBDC-NH2).
• Electrochemical testing of catalysts for CO2 reduction, including current density and faradaic efficiency measurements.
• In situ Fourier transform infrared spectroscopy (FTIR) to study reaction intermediates and catalyst behavior.

Main Results:

• Crown ether modification significantly increased C2H4 selectivity and FE in CuBTC, CuBDC, and CuBDC-NH2 by 3.1, 1.7, and 2.4 times, respectively.
• CuBTC modified with crown ether achieved the highest C2H4 FE of approximately 52% at 120 mA cm-2.
• In situ FTIR and control experiments indicated that CE stabilizes Cu+ during catalyst reconstruction, favoring Cu2O formation and enhancing *CO adsorption via K+ enrichment.

Conclusions:

• Crown ether modification is an effective strategy to improve the performance of copper-based MOFs for selective CO2 electroconversion to ethylene.
• The enhanced performance is attributed to CE-induced catalyst reconstruction, stabilization of Cu+, and improved *CO adsorption and C-C coupling.
• This work provides insights into designing advanced catalysts for efficient and selective CO2 utilization.