Highly Selective CO₂ Electroreduction to C₂H₄ Using a Metal-Organic Framework with Dual Active Sites

Area of Science:

• Electrochemistry
• Materials Science
• Catalysis

Background:

• Electrocatalytic conversion of carbon dioxide (CO2) to valuable products like ethylene (C2H4) is crucial for sustainable energy and environmental applications.
• High energy barriers in CO hydrogenation and C-C coupling steps often lead to C1 compounds, limiting C2H4 production.

Purpose of the Study:

• To develop a highly efficient electrocatalyst for CO2 to C2H4 conversion.
• To investigate the mechanism behind enhanced catalytic performance.

Main Methods:

• Synthesis of a novel metal-organic framework, PcCu-Cu-O, comprising PcCu-(OH)8 ligands and CuO4 nodes.
• Electrochemical characterization including cyclic voltammetry and chronoamperometry.
• In-situ infrared spectroscopy and control experiments to probe reaction mechanisms.

Main Results:

• PcCu-Cu-O demonstrated significantly improved electrocatalytic performance for CO2 reduction to C2H4 compared to discrete copper-phthalocyanine.
• Achieved a Faradaic efficiency (FE) of 50(1)% for C2H4 and a current density of 7.3 mA cm-2 at -1.2 V vs RHE.
• Identified a synergistic effect between CuPc and CuO4 units facilitating CO migration and dimerization.

Conclusions:

• The PcCu-Cu-O electrocatalyst represents a state-of-the-art material for CO2 to C2H4 conversion.
• The enhanced performance is attributed to the cooperative action of CuPc and CuO4 sites, lowering the C-C coupling energy barrier.
• This work provides a new strategy for designing advanced catalysts for efficient CO2 utilization.